forked from Minki/linux
038d07a283
81 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Andy Lutomirski
|
1299ef1d88 |
x86/mm: Rename flush_tlb_single() and flush_tlb_one() to __flush_tlb_one_[user|kernel]()
flush_tlb_single() and flush_tlb_one() sound almost identical, but they really mean "flush one user translation" and "flush one kernel translation". Rename them to flush_tlb_one_user() and flush_tlb_one_kernel() to make the semantics more obvious. [ I was looking at some PTI-related code, and the flush-one-address code is unnecessarily hard to understand because the names of the helpers are uninformative. This came up during PTI review, but no one got around to doing it. ] Signed-off-by: Andy Lutomirski <luto@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Hugh Dickins <hughd@google.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Kees Cook <keescook@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Linux-MM <linux-mm@kvack.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Link: http://lkml.kernel.org/r/3303b02e3c3d049dc5235d5651e0ae6d29a34354.1517414378.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Tim Chen
|
18bf3c3ea8 |
x86/speculation: Use Indirect Branch Prediction Barrier in context switch
Flush indirect branches when switching into a process that marked itself
non dumpable. This protects high value processes like gpg better,
without having too high performance overhead.
If done naïvely, we could switch to a kernel idle thread and then back
to the original process, such as:
process A -> idle -> process A
In such scenario, we do not have to do IBPB here even though the process
is non-dumpable, as we are switching back to the same process after a
hiatus.
To avoid the redundant IBPB, which is expensive, we track the last mm
user context ID. The cost is to have an extra u64 mm context id to track
the last mm we were using before switching to the init_mm used by idle.
Avoiding the extra IBPB is probably worth the extra memory for this
common scenario.
For those cases where tlb_defer_switch_to_init_mm() returns true (non
PCID), lazy tlb will defer switch to init_mm, so we will not be changing
the mm for the process A -> idle -> process A switch. So IBPB will be
skipped for this case.
Thanks to the reviewers and Andy Lutomirski for the suggestion of
using ctx_id which got rid of the problem of mm pointer recycling.
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: ak@linux.intel.com
Cc: karahmed@amazon.de
Cc: arjan@linux.intel.com
Cc: torvalds@linux-foundation.org
Cc: linux@dominikbrodowski.net
Cc: peterz@infradead.org
Cc: bp@alien8.de
Cc: luto@kernel.org
Cc: pbonzini@redhat.com
Cc: gregkh@linux-foundation.org
Link: https://lkml.kernel.org/r/1517263487-3708-1-git-send-email-dwmw@amazon.co.uk
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Linus Torvalds
|
40548c6b6c |
Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 pti updates from Thomas Gleixner:
"This contains:
- a PTI bugfix to avoid setting reserved CR3 bits when PCID is
disabled. This seems to cause issues on a virtual machine at least
and is incorrect according to the AMD manual.
- a PTI bugfix which disables the perf BTS facility if PTI is
enabled. The BTS AUX buffer is not globally visible and causes the
CPU to fault when the mapping disappears on switching CR3 to user
space. A full fix which restores BTS on PTI is non trivial and will
be worked on.
- PTI bugfixes for EFI and trusted boot which make sure that the user
space visible page table entries have the NX bit cleared
- removal of dead code in the PTI pagetable setup functions
- add PTI documentation
- add a selftest for vsyscall to verify that the kernel actually
implements what it advertises.
- a sysfs interface to expose vulnerability and mitigation
information so there is a coherent way for users to retrieve the
status.
- the initial spectre_v2 mitigations, aka retpoline:
+ The necessary ASM thunk and compiler support
+ The ASM variants of retpoline and the conversion of affected ASM
code
+ Make LFENCE serializing on AMD so it can be used as speculation
trap
+ The RSB fill after vmexit
- initial objtool support for retpoline
As I said in the status mail this is the most of the set of patches
which should go into 4.15 except two straight forward patches still on
hold:
- the retpoline add on of LFENCE which waits for ACKs
- the RSB fill after context switch
Both should be ready to go early next week and with that we'll have
covered the major holes of spectre_v2 and go back to normality"
* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (28 commits)
x86,perf: Disable intel_bts when PTI
security/Kconfig: Correct the Documentation reference for PTI
x86/pti: Fix !PCID and sanitize defines
selftests/x86: Add test_vsyscall
x86/retpoline: Fill return stack buffer on vmexit
x86/retpoline/irq32: Convert assembler indirect jumps
x86/retpoline/checksum32: Convert assembler indirect jumps
x86/retpoline/xen: Convert Xen hypercall indirect jumps
x86/retpoline/hyperv: Convert assembler indirect jumps
x86/retpoline/ftrace: Convert ftrace assembler indirect jumps
x86/retpoline/entry: Convert entry assembler indirect jumps
x86/retpoline/crypto: Convert crypto assembler indirect jumps
x86/spectre: Add boot time option to select Spectre v2 mitigation
x86/retpoline: Add initial retpoline support
objtool: Allow alternatives to be ignored
objtool: Detect jumps to retpoline thunks
x86/pti: Make unpoison of pgd for trusted boot work for real
x86/alternatives: Fix optimize_nops() checking
sysfs/cpu: Fix typos in vulnerability documentation
x86/cpu/AMD: Use LFENCE_RDTSC in preference to MFENCE_RDTSC
...
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Thomas Gleixner
|
f10ee3dcc9 |
x86/pti: Fix !PCID and sanitize defines
The switch to the user space page tables in the low level ASM code sets
unconditionally bit 12 and bit 11 of CR3. Bit 12 is switching the base
address of the page directory to the user part, bit 11 is switching the
PCID to the PCID associated with the user page tables.
This fails on a machine which lacks PCID support because bit 11 is set in
CR3. Bit 11 is reserved when PCID is inactive.
While the Intel SDM claims that the reserved bits are ignored when PCID is
disabled, the AMD APM states that they should be cleared.
This went unnoticed as the AMD APM was not checked when the code was
developed and reviewed and test systems with Intel CPUs never failed to
boot. The report is against a Centos 6 host where the guest fails to boot,
so it's not yet clear whether this is a virt issue or can happen on real
hardware too, but thats irrelevant as the AMD APM clearly ask for clearing
the reserved bits.
Make sure that on non PCID machines bit 11 is not set by the page table
switching code.
Andy suggested to rename the related bits and masks so they are clearly
describing what they should be used for, which is done as well for clarity.
That split could have been done with alternatives but the macro hell is
horrible and ugly. This can be done on top if someone cares to remove the
extra orq. For now it's a straight forward fix.
Fixes:
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Linus Torvalds
|
52c90f2d32 |
Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 page table isolation fixes from Thomas Gleixner:
"Four patches addressing the PTI fallout as discussed and debugged
yesterday:
- Remove stale and pointless TLB flush invocations from the hotplug
code
- Remove stale preempt_disable/enable from __native_flush_tlb()
- Plug the memory leak in the write_ldt() error path"
* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/ldt: Make LDT pgtable free conditional
x86/ldt: Plug memory leak in error path
x86/mm: Remove preempt_disable/enable() from __native_flush_tlb()
x86/smpboot: Remove stale TLB flush invocations
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Thomas Gleixner
|
decab0888e |
x86/mm: Remove preempt_disable/enable() from __native_flush_tlb()
The preempt_disable/enable() pair in __native_flush_tlb() was added in commit: |
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Linus Torvalds
|
5aa90a8458 |
Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 page table isolation updates from Thomas Gleixner:
"This is the final set of enabling page table isolation on x86:
- Infrastructure patches for handling the extra page tables.
- Patches which map the various bits and pieces which are required to
get in and out of user space into the user space visible page
tables.
- The required changes to have CR3 switching in the entry/exit code.
- Optimizations for the CR3 switching along with documentation how
the ASID/PCID mechanism works.
- Updates to dump pagetables to cover the user space page tables for
W+X scans and extra debugfs files to analyze both the kernel and
the user space visible page tables
The whole functionality is compile time controlled via a config switch
and can be turned on/off on the command line as well"
* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits)
x86/ldt: Make the LDT mapping RO
x86/mm/dump_pagetables: Allow dumping current pagetables
x86/mm/dump_pagetables: Check user space page table for WX pages
x86/mm/dump_pagetables: Add page table directory to the debugfs VFS hierarchy
x86/mm/pti: Add Kconfig
x86/dumpstack: Indicate in Oops whether PTI is configured and enabled
x86/mm: Clarify the whole ASID/kernel PCID/user PCID naming
x86/mm: Use INVPCID for __native_flush_tlb_single()
x86/mm: Optimize RESTORE_CR3
x86/mm: Use/Fix PCID to optimize user/kernel switches
x86/mm: Abstract switching CR3
x86/mm: Allow flushing for future ASID switches
x86/pti: Map the vsyscall page if needed
x86/pti: Put the LDT in its own PGD if PTI is on
x86/mm/64: Make a full PGD-entry size hole in the memory map
x86/events/intel/ds: Map debug buffers in cpu_entry_area
x86/cpu_entry_area: Add debugstore entries to cpu_entry_area
x86/mm/pti: Map ESPFIX into user space
x86/mm/pti: Share entry text PMD
x86/entry: Align entry text section to PMD boundary
...
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Peter Zijlstra
|
0a126abd57 |
x86/mm: Clarify the whole ASID/kernel PCID/user PCID naming
Ideally we'd also use sparse to enforce this separation so it becomes much more difficult to mess up. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: linux-mm@kvack.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Dave Hansen
|
6cff64b86a |
x86/mm: Use INVPCID for __native_flush_tlb_single()
This uses INVPCID to shoot down individual lines of the user mapping instead of marking the entire user map as invalid. This could/might/possibly be faster. This for sure needs tlb_single_page_flush_ceiling to be redetermined; esp. since INVPCID is _slow_. A detailed performance analysis is available here: https://lkml.kernel.org/r/3062e486-3539-8a1f-5724-16199420be71@intel.com [ Peterz: Split out from big combo patch ] Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Peter Zijlstra
|
6fd166aae7 |
x86/mm: Use/Fix PCID to optimize user/kernel switches
We can use PCID to retain the TLBs across CR3 switches; including those now part of the user/kernel switch. This increases performance of kernel entry/exit at the cost of more expensive/complicated TLB flushing. Now that we have two address spaces, one for kernel and one for user space, we need two PCIDs per mm. We use the top PCID bit to indicate a user PCID (just like we use the PFN LSB for the PGD). Since we do TLB invalidation from kernel space, the existing code will only invalidate the kernel PCID, we augment that by marking the corresponding user PCID invalid, and upon switching back to userspace, use a flushing CR3 write for the switch. In order to access the user_pcid_flush_mask we use PER_CPU storage, which means the previously established SWAPGS vs CR3 ordering is now mandatory and required. Having to do this memory access does require additional registers, most sites have a functioning stack and we can spill one (RAX), sites without functional stack need to otherwise provide the second scratch register. Note: PCID is generally available on Intel Sandybridge and later CPUs. Note: Up until this point TLB flushing was broken in this series. Based-on-code-from: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Dave Hansen
|
2ea907c4fe |
x86/mm: Allow flushing for future ASID switches
If changing the page tables in such a way that an invalidation of all
contexts (aka. PCIDs / ASIDs) is required, they can be actively invalidated
by:
1. INVPCID for each PCID (works for single pages too).
2. Load CR3 with each PCID without the NOFLUSH bit set
3. Load CR3 with the NOFLUSH bit set for each and do INVLPG for each address.
But, none of these are really feasible since there are ~6 ASIDs (12 with
PAGE_TABLE_ISOLATION) at the time that invalidation is required.
Instead of actively invalidating them, invalidate the *current* context and
also mark the cpu_tlbstate _quickly_ to indicate future invalidation to be
required.
At the next context-switch, look for this indicator
('invalidate_other' being set) invalidate all of the
cpu_tlbstate.ctxs[] entries.
This ensures that any future context switches will do a full flush
of the TLB, picking up the previous changes.
[ tglx: Folded more fixups from Peter ]
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Linus Torvalds
|
caf9a82657 |
Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 PTI preparatory patches from Thomas Gleixner:
"Todays Advent calendar window contains twentyfour easy to digest
patches. The original plan was to have twenty three matching the date,
but a late fixup made that moot.
- Move the cpu_entry_area mapping out of the fixmap into a separate
address space. That's necessary because the fixmap becomes too big
with NRCPUS=8192 and this caused already subtle and hard to
diagnose failures.
The top most patch is fresh from today and cures a brain slip of
that tall grumpy german greybeard, who ignored the intricacies of
32bit wraparounds.
- Limit the number of CPUs on 32bit to 64. That's insane big already,
but at least it's small enough to prevent address space issues with
the cpu_entry_area map, which have been observed and debugged with
the fixmap code
- A few TLB flush fixes in various places plus documentation which of
the TLB functions should be used for what.
- Rename the SYSENTER stack to CPU_ENTRY_AREA stack as it is used for
more than sysenter now and keeping the name makes backtraces
confusing.
- Prevent LDT inheritance on exec() by moving it to arch_dup_mmap(),
which is only invoked on fork().
- Make vysycall more robust.
- A few fixes and cleanups of the debug_pagetables code. Check
PAGE_PRESENT instead of checking the PTE for 0 and a cleanup of the
C89 initialization of the address hint array which already was out
of sync with the index enums.
- Move the ESPFIX init to a different place to prepare for PTI.
- Several code moves with no functional change to make PTI
integration simpler and header files less convoluted.
- Documentation fixes and clarifications"
* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
x86/cpu_entry_area: Prevent wraparound in setup_cpu_entry_area_ptes() on 32bit
init: Invoke init_espfix_bsp() from mm_init()
x86/cpu_entry_area: Move it out of the fixmap
x86/cpu_entry_area: Move it to a separate unit
x86/mm: Create asm/invpcid.h
x86/mm: Put MMU to hardware ASID translation in one place
x86/mm: Remove hard-coded ASID limit checks
x86/mm: Move the CR3 construction functions to tlbflush.h
x86/mm: Add comments to clarify which TLB-flush functions are supposed to flush what
x86/mm: Remove superfluous barriers
x86/mm: Use __flush_tlb_one() for kernel memory
x86/microcode: Dont abuse the TLB-flush interface
x86/uv: Use the right TLB-flush API
x86/entry: Rename SYSENTER_stack to CPU_ENTRY_AREA_entry_stack
x86/doc: Remove obvious weirdnesses from the x86 MM layout documentation
x86/mm/64: Improve the memory map documentation
x86/ldt: Prevent LDT inheritance on exec
x86/ldt: Rework locking
arch, mm: Allow arch_dup_mmap() to fail
x86/vsyscall/64: Warn and fail vsyscall emulation in NATIVE mode
...
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Peter Zijlstra
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1a3b0caeb7 |
x86/mm: Create asm/invpcid.h
Unclutter tlbflush.h a little. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: linux-mm@kvack.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Dave Hansen
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dd95f1a4b5 |
x86/mm: Put MMU to hardware ASID translation in one place
There are effectively two ASID types: 1. The one stored in the mmu_context that goes from 0..5 2. The one programmed into the hardware that goes from 1..6 This consolidates the locations where converting between the two (by doing a +1) to a single place which gives us a nice place to comment. PAGE_TABLE_ISOLATION will also need to, given an ASID, know which hardware ASID to flush for the userspace mapping. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: linux-mm@kvack.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Dave Hansen
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cb0a9144a7 |
x86/mm: Remove hard-coded ASID limit checks
First, it's nice to remove the magic numbers. Second, PAGE_TABLE_ISOLATION is going to consume half of the available ASID space. The space is currently unused, but add a comment to spell out this new restriction. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: linux-mm@kvack.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Dave Hansen
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50fb83a62c |
x86/mm: Move the CR3 construction functions to tlbflush.h
For flushing the TLB, the ASID which has been programmed into the hardware must be known. That differs from what is in 'cpu_tlbstate'. Add functions to transform the 'cpu_tlbstate' values into to the one programmed into the hardware (CR3). It's not easy to include mmu_context.h into tlbflush.h, so just move the CR3 building over to tlbflush.h. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: linux-mm@kvack.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Peter Zijlstra
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3f67af51e5 |
x86/mm: Add comments to clarify which TLB-flush functions are supposed to flush what
Per popular request.. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: linux-mm@kvack.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Peter Zijlstra
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b5fc6d9438 |
x86/mm: Remove superfluous barriers
atomic64_inc_return() already implies smp_mb() before and after. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: linux-mm@kvack.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Peter Zijlstra
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23cb7d46f3 |
x86/microcode: Dont abuse the TLB-flush interface
Commit:
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Nadav Amit
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9d0b62328d |
x86/tlb: Disable interrupts when changing CR4
CR4 modifications are implemented as RMW operations which update a shadow variable and write the result to CR4. The RMW operation is protected by preemption disable, but there is no enforcement or debugging mechanism. CR4 modifications happen also in interrupt context via __native_flush_tlb_global(). This implementation does not affect a interrupted thread context CR4 operation, because the CR4 toggle restores the original content and does not modify the shadow variable. So the current situation seems to be safe, but a recent patch tried to add an actual RMW operation in interrupt context, which will cause subtle corruptions. To prevent that and make the CR4 handling future proof: - Add a lockdep assertion to __cr4_set() which will catch interrupt enabled invocations - Disable interrupts in the cr4 manipulator inlines - Rename cr4_toggle_bits() to cr4_toggle_bits_irqsoff(). This is called from __switch_to_xtra() where interrupts are already disabled and performance matters. All other call sites are not performance critical, so the extra overhead of an additional local_irq_save/restore() pair is not a problem. If new call sites care about performance then the necessary _irqsoff() variants can be added. [ tglx: Condensed the patch by moving the irq protection inside the manipulator functions. Updated changelog ] Signed-off-by: Nadav Amit <namit@vmware.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Luck <tony.luck@intel.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: nadav.amit@gmail.com Cc: linux-edac@vger.kernel.org Link: https://lkml.kernel.org/r/20171125032907.2241-3-namit@vmware.com |
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Nadav Amit
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0c3292ca80 |
x86/tlb: Refactor CR4 setting and shadow write
Refactor the write to CR4 and its shadow value. This is done in preparation for the addition of an assertion to check that IRQs are disabled during CR4 update. No functional change. Signed-off-by: Nadav Amit <namit@vmware.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: nadav.amit@gmail.com Cc: Andy Lutomirski <luto@kernel.org> Cc: linux-edac@vger.kernel.org Link: https://lkml.kernel.org/r/20171125032907.2241-2-namit@vmware.com |
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Greg Kroah-Hartman
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b24413180f |
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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Andy Lutomirski
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7ac7f2c315 |
x86/mm: Remove debug/x86/tlb_defer_switch_to_init_mm
Borislav thinks that we don't need this knob in a released kernel.
Get rid of it.
Requested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes:
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Andy Lutomirski
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4e57b94664 |
x86/mm: Tidy up "x86/mm: Flush more aggressively in lazy TLB mode"
Due to timezones, commit: |
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Andy Lutomirski
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b956575bed |
x86/mm: Flush more aggressively in lazy TLB mode
Since commit: |
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Andy Lutomirski
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72c0098d92 |
x86/mm: Reinitialize TLB state on hotplug and resume
When Linux brings a CPU down and back up, it switches to init_mm and then
loads swapper_pg_dir into CR3. With PCID enabled, this has the side effect
of masking off the ASID bits in CR3.
This can result in some confusion in the TLB handling code. If we
bring a CPU down and back up with any ASID other than 0, we end up
with the wrong ASID active on the CPU after resume. This could
cause our internal state to become corrupt, although major
corruption is unlikely because init_mm doesn't have any user pages.
More obviously, if CONFIG_DEBUG_VM=y, we'll trip over an assertion
in the next context switch. The result of *that* is a failure to
resume from suspend with probability 1 - 1/6^(cpus-1).
Fix it by reinitializing cpu_tlbstate on resume and CPU bringup.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Jiri Kosina <jikos@kernel.org>
Fixes:
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Andy Lutomirski
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10af6235e0 |
x86/mm: Implement PCID based optimization: try to preserve old TLB entries using PCID
PCID is a "process context ID" -- it's what other architectures call
an address space ID. Every non-global TLB entry is tagged with a
PCID, only TLB entries that match the currently selected PCID are
used, and we can switch PGDs without flushing the TLB. x86's
PCID is 12 bits.
This is an unorthodox approach to using PCID. x86's PCID is far too
short to uniquely identify a process, and we can't even really
uniquely identify a running process because there are monster
systems with over 4096 CPUs. To make matters worse, past attempts
to use all 12 PCID bits have resulted in slowdowns instead of
speedups.
This patch uses PCID differently. We use a PCID to identify a
recently-used mm on a per-cpu basis. An mm has no fixed PCID
binding at all; instead, we give it a fresh PCID each time it's
loaded except in cases where we want to preserve the TLB, in which
case we reuse a recent value.
Here are some benchmark results, done on a Skylake laptop at 2.3 GHz
(turbo off, intel_pstate requesting max performance) under KVM with
the guest using idle=poll (to avoid artifacts when bouncing between
CPUs). I haven't done any real statistics here -- I just ran them
in a loop and picked the fastest results that didn't look like
outliers. Unpatched means commit
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Andy Lutomirski
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660da7c922 |
x86/mm: Enable CR4.PCIDE on supported systems
We can use PCID if the CPU has PCID and PGE and we're not on Xen. By itself, this has no effect. A followup patch will start using PCID. Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Nadav Amit <nadav.amit@gmail.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/6327ecd907b32f79d5aa0d466f04503bbec5df88.1498751203.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Andy Lutomirski
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94b1b03b51 |
x86/mm: Rework lazy TLB mode and TLB freshness tracking
x86's lazy TLB mode used to be fairly weak -- it would switch to
init_mm the first time it tried to flush a lazy TLB. This meant an
unnecessary CR3 write and, if the flush was remote, an unnecessary
IPI.
Rewrite it entirely. When we enter lazy mode, we simply remove the
CPU from mm_cpumask. This means that we need a way to figure out
whether we've missed a flush when we switch back out of lazy mode.
I use the tlb_gen machinery to track whether a context is up to
date.
Note to reviewers: this patch, my itself, looks a bit odd. I'm
using an array of length 1 containing (ctx_id, tlb_gen) rather than
just storing tlb_gen, and making it at array isn't necessary yet.
I'm doing this because the next few patches add PCID support, and,
with PCID, we need ctx_id, and the array will end up with a length
greater than 1. Making it an array now means that there will be
less churn and therefore less stress on your eyeballs.
NB: This is dubious but, AFAICT, still correct on Xen and UV.
xen_exit_mmap() uses mm_cpumask() for nefarious purposes and this
patch changes the way that mm_cpumask() works. This should be okay,
since Xen *also* iterates all online CPUs to find all the CPUs it
needs to twiddle.
The UV tlbflush code is rather dated and should be changed.
Here are some benchmark results, done on a Skylake laptop at 2.3 GHz
(turbo off, intel_pstate requesting max performance) under KVM with
the guest using idle=poll (to avoid artifacts when bouncing between
CPUs). I haven't done any real statistics here -- I just ran them
in a loop and picked the fastest results that didn't look like
outliers. Unpatched means commit
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Andy Lutomirski
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b0579ade7c |
x86/mm: Track the TLB's tlb_gen and update the flushing algorithm
There are two kernel features that would benefit from tracking how up-to-date each CPU's TLB is in the case where IPIs aren't keeping it up to date in real time: - Lazy mm switching currently works by switching to init_mm when it would otherwise flush. This is wasteful: there isn't fundamentally any need to update CR3 at all when going lazy or when returning from lazy mode, nor is there any need to receive flush IPIs at all. Instead, we should just stop trying to keep the TLB coherent when we go lazy and, when unlazying, check whether we missed any flushes. - PCID will let us keep recent user contexts alive in the TLB. If we start doing this, we need a way to decide whether those contexts are up to date. On some paravirt systems, remote TLBs can be flushed without IPIs. This won't update the target CPUs' tlb_gens, which may cause unnecessary local flushes later on. We can address this if it becomes a problem by carefully updating the target CPU's tlb_gen directly. By itself, this patch is a very minor optimization that avoids unnecessary flushes when multiple TLB flushes targetting the same CPU race. The complexity in this patch would not be worth it on its own, but it will enable improved lazy TLB tracking and PCID. Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Nadav Amit <nadav.amit@gmail.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/1210fb244bc9cbe7677f7f0b72db4d359675f24b.1498751203.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Andy Lutomirski
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f39681ed0f |
x86/mm: Give each mm TLB flush generation a unique ID
This adds two new variables to mmu_context_t: ctx_id and tlb_gen. ctx_id uniquely identifies the mm_struct and will never be reused. For a given mm_struct (and hence ctx_id), tlb_gen is a monotonic count of the number of times that a TLB flush has been requested. The pair (ctx_id, tlb_gen) can be used as an identifier for TLB flush actions and will be used in subsequent patches to reliably determine whether all needed TLB flushes have occurred on a given CPU. This patch is split out for ease of review. By itself, it has no real effect other than creating and updating the new variables. Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Nadav Amit <nadav.amit@gmail.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/413a91c24dab3ed0caa5f4e4d017d87b0857f920.1498751203.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Andy Lutomirski
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d54368127a |
x86/mm: Remove reset_lazy_tlbstate()
The only call site also calls idle_task_exit(), and idle_task_exit() puts us into a clean state by explicitly switching to init_mm. Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Borislav Petkov <bp@suse.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Nadav Amit <nadav.amit@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/3acc7ad02a2ec060d2321a1e0f6de1cb90069517.1498022414.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Andy Lutomirski
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6c690ee103 |
x86/mm: Split read_cr3() into read_cr3_pa() and __read_cr3()
The kernel has several code paths that read CR3. Most of them assume that CR3 contains the PGD's physical address, whereas some of them awkwardly use PHYSICAL_PAGE_MASK to mask off low bits. Add explicit mask macros for CR3 and convert all of the CR3 readers. This will keep them from breaking when PCID is enabled. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: xen-devel <xen-devel@lists.xen.org> Link: http://lkml.kernel.org/r/883f8fb121f4616c1c1427ad87350bb2f5ffeca1.1497288170.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Andy Lutomirski
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3d28ebceaf |
x86/mm: Rework lazy TLB to track the actual loaded mm
Lazy TLB state is currently managed in a rather baroque manner. AFAICT, there are three possible states: - Non-lazy. This means that we're running a user thread or a kernel thread that has called use_mm(). current->mm == current->active_mm == cpu_tlbstate.active_mm and cpu_tlbstate.state == TLBSTATE_OK. - Lazy with user mm. We're running a kernel thread without an mm and we're borrowing an mm_struct. We have current->mm == NULL, current->active_mm == cpu_tlbstate.active_mm, cpu_tlbstate.state != TLBSTATE_OK (i.e. TLBSTATE_LAZY or 0). The current cpu is set in mm_cpumask(current->active_mm). CR3 points to current->active_mm->pgd. The TLB is up to date. - Lazy with init_mm. This happens when we call leave_mm(). We have current->mm == NULL, current->active_mm == cpu_tlbstate.active_mm, but that mm is only relelvant insofar as the scheduler is tracking it for refcounting. cpu_tlbstate.state != TLBSTATE_OK. The current cpu is clear in mm_cpumask(current->active_mm). CR3 points to swapper_pg_dir, i.e. init_mm->pgd. This patch simplifies the situation. Other than perf, x86 stops caring about current->active_mm at all. We have cpu_tlbstate.loaded_mm pointing to the mm that CR3 references. The TLB is always up to date for that mm. leave_mm() just switches us to init_mm. There are no longer any special cases for mm_cpumask, and switch_mm() switches mms without worrying about laziness. After this patch, cpu_tlbstate.state serves only to tell the TLB flush code whether it may switch to init_mm instead of doing a normal flush. This makes fairly extensive changes to xen_exit_mmap(), which used to look a bit like black magic. Perf is unchanged. With or without this change, perf may behave a bit erratically if it tries to read user memory in kernel thread context. We should build on this patch to teach perf to never look at user memory when cpu_tlbstate.loaded_mm != current->mm. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bpetkov@suse.de> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.com> Cc: Nadav Amit <nadav.amit@gmail.com> Cc: Nadav Amit <namit@vmware.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mm@kvack.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Andy Lutomirski
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ce4a4e565f |
x86/mm: Remove the UP asm/tlbflush.h code, always use the (formerly) SMP code
The UP asm/tlbflush.h generates somewhat nicer code than the SMP version. Aside from that, it's fallen quite a bit behind the SMP code: - flush_tlb_mm_range() didn't flush individual pages if the range was small. - The lazy TLB code was much weaker. This usually wouldn't matter, but, if a kernel thread flushed its lazy "active_mm" more than once (due to reclaim or similar), it wouldn't be unlazied and would instead pointlessly flush repeatedly. - Tracepoints were missing. Aside from that, simply having the UP code around was a maintanence burden, since it means that any change to the TLB flush code had to make sure not to break it. Simplify everything by deleting the UP code. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bpetkov@suse.de> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.com> Cc: Nadav Amit <nadav.amit@gmail.com> Cc: Nadav Amit <namit@vmware.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mm@kvack.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Andy Lutomirski
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454bbad979 |
x86/mm: Refactor flush_tlb_mm_range() to merge local and remote cases
The local flush path is very similar to the remote flush path. Merge them. This is intended to make no difference to behavior whatsoever. It removes some code and will make future changes to the flushing mechanics simpler. This patch does remove one small optimization: flush_tlb_mm_range() now has an unconditional smp_mb() instead of using MOV to CR3 or INVLPG as a full barrier when applicable. I think this is okay for a few reasons. First, smp_mb() is quite cheap compared to the cost of a TLB flush. Second, this rearrangement makes a bigger optimization available: with some work on the SMP function call code, we could do the local and remote flushes in parallel. Third, I'm planning a rework of the TLB flush algorithm that will require an atomic operation at the beginning of each flush, and that operation will replace the smp_mb(). Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bpetkov@suse.de> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.com> Cc: Nadav Amit <nadav.amit@gmail.com> Cc: Nadav Amit <namit@vmware.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mm@kvack.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Andy Lutomirski
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a2055abe9c |
x86/mm: Pass flush_tlb_info to flush_tlb_others() etc
Rather than passing all the contents of flush_tlb_info to flush_tlb_others(), pass a pointer to the structure directly. For consistency, this also removes the unnecessary cpu parameter from uv_flush_tlb_others() to make its signature match the other *flush_tlb_others() functions. This serves two purposes: - It will dramatically simplify future patches that change struct flush_tlb_info, which I'm planning to do. - struct flush_tlb_info is an adequate description of what to do for a local flush, too, so by reusing it we can remove duplicated code between local and remove flushes in a future patch. Signed-off-by: Andy Lutomirski <luto@kernel.org> Acked-by: Rik van Riel <riel@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bpetkov@suse.de> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.com> Cc: Nadav Amit <nadav.amit@gmail.com> Cc: Nadav Amit <namit@vmware.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mm@kvack.org [ Fix build warning. ] Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Andy Lutomirski
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e73ad5ff2f |
mm, x86/mm: Make the batched unmap TLB flush API more generic
try_to_unmap_flush() used to open-code a rather x86-centric flush sequence: local_flush_tlb() + flush_tlb_others(). Rearrange the code so that the arch (only x86 for now) provides arch_tlbbatch_add_mm() and arch_tlbbatch_flush() and the core code calls those functions instead. I'll want this for x86 because, to enable address space ids, I can't support the flush_tlb_others() mode used by exising try_to_unmap_flush() implementation with good performance. I can support the new API fairly easily, though. I imagine that other architectures may be in a similar position. Architectures with strong remote flush primitives (arm64?) may have even worse performance problems with flush_tlb_others() the way that try_to_unmap_flush() uses it. Signed-off-by: Andy Lutomirski <luto@kernel.org> Acked-by: Kees Cook <keescook@chromium.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bpetkov@suse.de> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.com> Cc: Nadav Amit <nadav.amit@gmail.com> Cc: Nadav Amit <namit@vmware.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/19f25a8581f9fb77876b7ff3b001f89835e34ea3.1495492063.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Andy Lutomirski
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ca6c99c079 |
x86/mm: Reimplement flush_tlb_page() using flush_tlb_mm_range()
flush_tlb_page() was very similar to flush_tlb_mm_range() except that it had a couple of issues: - It was missing an smp_mb() in the case where current->active_mm != mm. (This is a longstanding bug reported by Nadav Amit) - It was missing tracepoints and vm counter updates. The only reason that I can see for keeping it at as a separate function is that it could avoid a few branches that flush_tlb_mm_range() needs to decide to flush just one page. This hardly seems worthwhile. If we decide we want to get rid of those branches again, a better way would be to introduce an __flush_tlb_mm_range() helper and make both flush_tlb_page() and flush_tlb_mm_range() use it. Signed-off-by: Andy Lutomirski <luto@kernel.org> Acked-by: Kees Cook <keescook@chromium.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bpetkov@suse.de> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.com> Cc: Nadav Amit <nadav.amit@gmail.com> Cc: Nadav Amit <namit@vmware.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/3cc3847cf888d8907577569b8bac3f01992ef8f9.1495492063.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Andy Lutomirski
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29961b59a5 |
x86/mm: Remove flush_tlb() and flush_tlb_current_task()
I was trying to figure out what how flush_tlb_current_task() would possibly work correctly if current->mm != current->active_mm, but I realized I could spare myself the effort: it has no callers except the unused flush_tlb() macro. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Nadav Amit <namit@vmware.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/e52d64c11690f85e9f1d69d7b48cc2269cd2e94b.1492844372.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Ingo Molnar
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1f9ca18404 |
Merge branch 'x86/process' into x86/mm, to create new base for further patches
Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Daniel Borkmann
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2c4ea6e28d |
x86/tlb: Fix tlb flushing when lguest clears PGE
Fengguang reported random corruptions from various locations on x86-32 after commits |
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Thomas Gleixner
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5a920155e3 |
x86/process: Optimize TIF_NOTSC switch
Provide and use a toggle helper instead of doing it with a branch. x86_64: arch/x86/kernel/process.o text data bss dec hex 3008 8577 16 11601 2d51 Before 2976 8577 16 11569 2d31 After i386: arch/x86/kernel/process.o text data bss dec hex 2925 8673 8 11606 2d56 Before 2893 8673 8 11574 2d36 After Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andy Lutomirski <luto@kernel.org> Link: http://lkml.kernel.org/r/20170214081104.9244-4-khuey@kylehuey.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> |
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Andy Lutomirski
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1ef55be16e |
x86/asm: Get rid of __read_cr4_safe()
We use __read_cr4() vs __read_cr4_safe() inconsistently. On CR4-less CPUs, all CR4 bits are effectively clear, so we can make the code simpler and more robust by making __read_cr4() always fix up faults on 32-bit kernels. This may fix some bugs on old 486-like CPUs, but I don't have any easy way to test that. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Brian Gerst <brgerst@gmail.com> Cc: Borislav Petkov <bp@alien8.de> Cc: david@saggiorato.net Link: http://lkml.kernel.org/r/ea647033d357d9ce2ad2bbde5a631045f5052fb6.1475178370.git.luto@kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de> |
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Andy Lutomirski
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e1bfc11c5a |
x86/init: Fix cr4_init_shadow() on CR4-less machines
cr4_init_shadow() will panic on 486-like machines without CR4. Fix
it using __read_cr4_safe().
Reported-by: david@saggiorato.net
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Fixes:
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Sebastian Andrzej Siewior
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5cf0791da5 |
x86/mm: Disable preemption during CR3 read+write
There's a subtle preemption race on UP kernels: Usually current->mm (and therefore mm->pgd) stays the same during the lifetime of a task so it does not matter if a task gets preempted during the read and write of the CR3. But then, there is this scenario on x86-UP: TaskA is in do_exit() and exit_mm() sets current->mm = NULL followed by: -> mmput() -> exit_mmap() -> tlb_finish_mmu() -> tlb_flush_mmu() -> tlb_flush_mmu_tlbonly() -> tlb_flush() -> flush_tlb_mm_range() -> __flush_tlb_up() -> __flush_tlb() -> __native_flush_tlb() At this point current->mm is NULL but current->active_mm still points to the "old" mm. Let's preempt taskA _after_ native_read_cr3() by taskB. TaskB has its own mm so CR3 has changed. Now preempt back to taskA. TaskA has no ->mm set so it borrows taskB's mm and so CR3 remains unchanged. Once taskA gets active it continues where it was interrupted and that means it writes its old CR3 value back. Everything is fine because userland won't need its memory anymore. Now the fun part: Let's preempt taskA one more time and get back to taskB. This time switch_mm() won't do a thing because oldmm (->active_mm) is the same as mm (as per context_switch()). So we remain with a bad CR3 / PGD and return to userland. The next thing that happens is handle_mm_fault() with an address for the execution of its code in userland. handle_mm_fault() realizes that it has a PTE with proper rights so it returns doing nothing. But the CPU looks at the wrong PGD and insists that something is wrong and faults again. And again. And one more time… This pagefault circle continues until the scheduler gets tired of it and puts another task on the CPU. It gets little difficult if the task is a RT task with a high priority. The system will either freeze or it gets fixed by the software watchdog thread which usually runs at RT-max prio. But waiting for the watchdog will increase the latency of the RT task which is no good. Fix this by disabling preemption across the critical code section. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Borislav Petkov <bp@suse.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mm@kvack.org Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1470404259-26290-1-git-send-email-bigeasy@linutronix.de [ Prettified the changelog. ] Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Ingo Molnar
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6666ea558b |
Linux 4.6-rc4
-----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAABAgAGBQJXFELfAAoJEHm+PkMAQRiGRYIH+wWsUva7TR9arN1ZrURvI17b KqyQH8Ov9zJBsIaq/rFXOr5KfNgx7BU9BL9h7QkBy693HXTWf+GTZ1czHM4N12C3 0ZdHGrLwTHo2zdisiQaFORZSfhSVTUNGXGHXw13bUMgEqatPgkozXEnsvXXNdt1Z HtlcuJn3pcj+QIY7qDXZgTLTwgn248hi1AgNag+ntFcWiz21IYaMIi7/mCY9QUIi AY+Y3hqFQM7/8cVyThGS5wZPTg1YzdhsLJpoCk0TbS8FvMEnA+ylcTgc15C78bwu AxOwM3OCmH4gMsd7Dd/O+i9lE3K6PFrgzdDisYL3P7eHap+EdiLDvVzPDPPx0xg= =Q7r3 -----END PGP SIGNATURE----- Merge tag 'v4.6-rc4' into x86/asm, to pick up fixes Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Nadav Amit
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858eaaa711 |
mm/rmap: batched invalidations should use existing api
The recently introduced batched invalidations mechanism uses its own
mechanism for shootdown. However, it does wrong accounting of
interrupts (e.g., inc_irq_stat is called for local invalidations),
trace-points (e.g., TLB_REMOTE_SHOOTDOWN for local invalidations) and
may break some platforms as it bypasses the invalidation mechanisms of
Xen and SGI UV.
This patch reuses the existing TLB flushing mechnaisms instead. We use
NULL as mm to indicate a global invalidation is required.
Fixes
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Borislav Petkov
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c109bf9599 |
x86/cpufeature: Remove cpu_has_pge
Use static_cpu_has() in __flush_tlb_all() due to the time-sensitivity of this one. Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1459266123-21878-10-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Linus Torvalds
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13c76ad872 |
Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 mm updates from Ingo Molnar:
"The main changes in this cycle were:
- Enable full ASLR randomization for 32-bit programs (Hector
Marco-Gisbert)
- Add initial minimal INVPCI support, to flush global mappings (Andy
Lutomirski)
- Add KASAN enhancements (Andrey Ryabinin)
- Fix mmiotrace for huge pages (Karol Herbst)
- ... misc cleanups and small enhancements"
* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/mm/32: Enable full randomization on i386 and X86_32
x86/mm/kmmio: Fix mmiotrace for hugepages
x86/mm: Avoid premature success when changing page attributes
x86/mm/ptdump: Remove paravirt_enabled()
x86/mm: Fix INVPCID asm constraint
x86/dmi: Switch dmi_remap() from ioremap() [uncached] to ioremap_cache()
x86/mm: If INVPCID is available, use it to flush global mappings
x86/mm: Add a 'noinvpcid' boot option to turn off INVPCID
x86/mm: Add INVPCID helpers
x86/kasan: Write protect kasan zero shadow
x86/kasan: Clear kasan_zero_page after TLB flush
x86/mm/numa: Check for failures in numa_clear_kernel_node_hotplug()
x86/mm/numa: Clean up numa_clear_kernel_node_hotplug()
x86/mm: Make kmap_prot into a #define
x86/mm/32: Set NX in __supported_pte_mask before enabling paging
x86/mm: Streamline and restore probe_memory_block_size()
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