Improve the warning messages to show the relevant function name+offset.
This makes it much easier to diagnose problems with the ORC metadata.
Before:
WARNING: can't dereference iret registers at ffff8801c5f17fe0 for ip ffffffff95f0d94b
After:
WARNING: can't dereference iret registers at ffff880178f5ffe0 for ip int3+0x5b/0x60
Reported-by: Andrei Vagin <avagin@virtuozzo.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: 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: ee9f8fce99 ("x86/unwind: Add the ORC unwinder")
Link: http://lkml.kernel.org/r/6bada6b9eac86017e16bd79e1e77877935cb50bb.1508516398.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This fixes the following ORC warning in the 'int3' entry code:
WARNING: can't dereference iret registers at ffff8801c5f17fe0 for ip ffffffff95f0d94b
The ORC metadata had the wrong stack offset for the iret registers.
Their location on the stack is dependent on whether the exception has an
error code.
Reported-and-tested-by: Andrei Vagin <avagin@virtuozzo.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: 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: 8c1f75587a ("x86/entry/64: Add unwind hint annotations")
Link: http://lkml.kernel.org/r/931d57f0551ed7979d5e7e05370d445c8e5137f8.1508516398.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Some F14h machines have an erratum which, "under a highly specific
and detailed set of internal timing conditions" can lead to skipping
instructions and RIP corruption.
Add the fix for those machines when their BIOS doesn't apply it or
there simply isn't BIOS update for them.
Tested-by: <mirh@protonmail.ch>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sherry Hurwitz <sherry.hurwitz@amd.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yazen Ghannam <Yazen.Ghannam@amd.com>
Link: http://lkml.kernel.org/r/20171022104731.28249-1-bp@alien8.de
Link: https://bugzilla.kernel.org/show_bug.cgi?id=197285
[ Added pr_info() that we activated the workaround. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We do not have tracepoints for sys_modify_ldt() because we define
it directly instead of using the normal SYSCALL_DEFINEx() macros.
However, there is a reason sys_modify_ldt() does not use the macros:
it has an 'int' return type instead of 'unsigned long'. This is
a bug, but it's a bug cemented in the ABI.
What does this mean? If we return -EINVAL from a function that
returns 'int', we have 0x00000000ffffffea in %rax. But, if we
return -EINVAL from a function returning 'unsigned long', we end
up with 0xffffffffffffffea in %rax, which is wrong.
To work around this and maintain the 'int' behavior while using
the SYSCALL_DEFINEx() macros, so we add a cast to 'unsigned int'
in both implementations of sys_modify_ldt().
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Brian Gerst <brgerst@gmail.com>
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/20171018172107.1A79C532@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently, it is possible to mmap() any offset from /dev/mem. If a
program mmaps() /dev/mem offsets outside of the addressable limits
of a system, the page table can be corrupted by setting reserved bits.
For example if you mmap() offset 0x0001000000000000 of /dev/mem on an
x86_64 system with a 48-bit bus, the page fault handler will be called
with error_code set to RSVD. The kernel then crashes with a page table
corruption error.
This change prevents this page table corruption on x86 by refusing
to mmap offsets higher than the highest valid address in the system.
Signed-off-by: Craig Bergstrom <craigb@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
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: Luis R. Rodriguez <mcgrof@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: dsafonov@virtuozzo.com
Cc: kirill.shutemov@linux.intel.com
Cc: mhocko@suse.com
Cc: oleg@redhat.com
Link: http://lkml.kernel.org/r/20171019192856.39672-1-craigb@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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: b956575bed ("x86/mm: Flush more aggressively in lazy TLB mode")
Link: http://lkml.kernel.org/r/1fa72431924e81e86c164ff7881bf9240d1f1a6c.1508000261.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Due to timezones, commit:
b956575bed ("x86/mm: Flush more aggressively in lazy TLB mode")
was an outdated patch that well tested and fixed the bug but didn't
address Borislav's review comments.
Tidy it up:
- The name "tlb_use_lazy_mode()" was highly confusing. Change it to
"tlb_defer_switch_to_init_mm()", which describes what it actually
means.
- Move the static_branch crap into a helper.
- Improve comments.
Actually removing the debugfs option is in the next patch.
Reported-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: b956575bed ("x86/mm: Flush more aggressively in lazy TLB mode")
Link: http://lkml.kernel.org/r/154ef95428d4592596b6e98b0af1d2747d6cfbf8.1508000261.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Blacklist Broadwell X model 79 for late loading due to an erratum.
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Tony Luck <tony.luck@intel.com>
Cc: <stable@vger.kernel.org>
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/20171018111225.25635-1-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Moving the early IDT setup out of assembly code breaks the boot on first
generation 486 systems.
The reason is that the call of idt_setup_early_handler, which sets up the
early handlers was added after the call to cr4_init_shadow().
cr4_init_shadow() tries to read CR4 which is not available on those
systems. The accessor function uses a extable fixup to handle the resulting
fault. As the IDT is not set up yet, the cr4 read exception causes an
instantaneous reboot for obvious reasons.
Call idt_setup_early_handler() before cr4_init_shadow() so IDT is set up
before the first exception hits.
Fixes: 87e81786b1 ("x86/idt: Move early IDT setup out of 32-bit asm")
Reported-and-tested-by: Matthew Whitehead <whiteheadm@acm.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1710161210290.1973@nanos
The 'this_leaf' variable is assigned a value that is never
read and it is updated a little later with a newer value,
hence we can remove the redundant assignment.
Cleans up the following Clang warning:
Value stored to 'this_leaf' is never read
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-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>
Cc: kernel-janitors@vger.kernel.org
Link: http://lkml.kernel.org/r/20171015160203.12332-1-colin.king@canonical.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull x86 fixes from Ingo Molnar:
"A landry list of fixes:
- fix reboot breakage on some PCID-enabled system
- fix crashes/hangs on some PCID-enabled systems
- fix microcode loading on certain older CPUs
- various unwinder fixes
- extend an APIC quirk to more hardware systems and disable APIC
related warning on virtualized systems
- various Hyper-V fixes
- a macro definition robustness fix
- remove jprobes IRQ disabling
- various mem-encryption fixes"
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/microcode: Do the family check first
x86/mm: Flush more aggressively in lazy TLB mode
x86/apic: Update TSC_DEADLINE quirk with additional SKX stepping
x86/apic: Silence "FW_BUG TSC_DEADLINE disabled due to Errata" on hypervisors
x86/mm: Disable various instrumentations of mm/mem_encrypt.c and mm/tlb.c
x86/hyperv: Fix hypercalls with extended CPU ranges for TLB flushing
x86/hyperv: Don't use percpu areas for pcpu_flush/pcpu_flush_ex structures
x86/hyperv: Clear vCPU banks between calls to avoid flushing unneeded vCPUs
x86/unwind: Disable unwinder warnings on 32-bit
x86/unwind: Align stack pointer in unwinder dump
x86/unwind: Use MSB for frame pointer encoding on 32-bit
x86/unwind: Fix dereference of untrusted pointer
x86/alternatives: Fix alt_max_short macro to really be a max()
x86/mm/64: Fix reboot interaction with CR4.PCIDE
kprobes/x86: Remove IRQ disabling from jprobe handlers
kprobes/x86: Set up frame pointer in kprobe trampoline
Pull RAS fixes from Ingo Molnar:
"A boot parameter fix, plus a header export fix"
* 'ras-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/mce: Hide mca_cfg
RAS/CEC: Use the right length for "cec_disable"
Pull perf fixes from Ingo Molnar:
"Some tooling fixes plus three kernel fixes: a memory leak fix, a
statistics fix and a crash fix"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86/intel/uncore: Fix memory leaks on allocation failures
perf/core: Fix cgroup time when scheduling descendants
perf/core: Avoid freeing static PMU contexts when PMU is unregistered
tools include uapi bpf.h: Sync kernel ABI header with tooling header
perf pmu: Unbreak perf record for arm/arm64 with events with explicit PMU
perf script: Add missing separator for "-F ip,brstack" (and brstackoff)
perf callchain: Compare dsos (as well) for CCKEY_FUNCTION
On CPUs like AMD's Geode, for example, we shouldn't even try to load
microcode because they do not support the modern microcode loading
interface.
However, we do the family check *after* the other checks whether the
loader has been disabled on the command line or whether we're running in
a guest.
So move the family checks first in order to exit early if we're being
loaded on an unsupported family.
Reported-and-tested-by: Sven Glodowski <glodi1@arcor.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org> # 4.11..
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://bugzilla.suse.com/show_bug.cgi?id=1061396
Link: http://lkml.kernel.org/r/20171012112316.977-1-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The ORC unwinder has been stable in testing so far. Give it much wider
testing by making it the default in kconfig for x86_64. It's not yet
supported for 32-bit, so leave frame pointers as the default there.
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
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/9b1237bbe7244ed9cdf8db2dcb1253e37e1c341e.1507924831.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Rename the unwinder config options from:
CONFIG_ORC_UNWINDER
CONFIG_FRAME_POINTER_UNWINDER
CONFIG_GUESS_UNWINDER
to:
CONFIG_UNWINDER_ORC
CONFIG_UNWINDER_FRAME_POINTER
CONFIG_UNWINDER_GUESS
... in order to give them a more logical config namespace.
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
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/73972fc7e2762e91912c6b9584582703d6f1b8cc.1507924831.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since commit:
94b1b03b51 ("x86/mm: Rework lazy TLB mode and TLB freshness tracking")
x86's lazy TLB mode has been all the way lazy: when running a kernel thread
(including the idle thread), the kernel keeps using the last user mm's
page tables without attempting to maintain user TLB coherence at all.
From a pure semantic perspective, this is fine -- kernel threads won't
attempt to access user pages, so having stale TLB entries doesn't matter.
Unfortunately, I forgot about a subtlety. By skipping TLB flushes,
we also allow any paging-structure caches that may exist on the CPU
to become incoherent. This means that we can have a
paging-structure cache entry that references a freed page table, and
the CPU is within its rights to do a speculative page walk starting
at the freed page table.
I can imagine this causing two different problems:
- A speculative page walk starting from a bogus page table could read
IO addresses. I haven't seen any reports of this causing problems.
- A speculative page walk that involves a bogus page table can install
garbage in the TLB. Such garbage would always be at a user VA, but
some AMD CPUs have logic that triggers a machine check when it notices
these bogus entries. I've seen a couple reports of this.
Boris further explains the failure mode:
> It is actually more of an optimization which assumes that paging-structure
> entries are in WB DRAM:
>
> "TlbCacheDis: cacheable memory disable. Read-write. 0=Enables
> performance optimization that assumes PML4, PDP, PDE, and PTE entries
> are in cacheable WB-DRAM; memory type checks may be bypassed, and
> addresses outside of WB-DRAM may result in undefined behavior or NB
> protocol errors. 1=Disables performance optimization and allows PML4,
> PDP, PDE and PTE entries to be in any memory type. Operating systems
> that maintain page tables in memory types other than WB- DRAM must set
> TlbCacheDis to insure proper operation."
>
> The MCE generated is an NB protocol error to signal that
>
> "Link: A specific coherent-only packet from a CPU was issued to an
> IO link. This may be caused by software which addresses page table
> structures in a memory type other than cacheable WB-DRAM without
> properly configuring MSRC001_0015[TlbCacheDis]. This may occur, for
> example, when page table structure addresses are above top of memory. In
> such cases, the NB will generate an MCE if it sees a mismatch between
> the memory operation generated by the core and the link type."
>
> I'm assuming coherent-only packets don't go out on IO links, thus the
> error.
To fix this, reinstate TLB coherence in lazy mode. With this patch
applied, we do it in one of two ways:
- If we have PCID, we simply switch back to init_mm's page tables
when we enter a kernel thread -- this seems to be quite cheap
except for the cost of serializing the CPU.
- If we don't have PCID, then we set a flag and switch to init_mm
the first time we would otherwise need to flush the TLB.
The /sys/kernel/debug/x86/tlb_use_lazy_mode debug switch can be changed
to override the default mode for benchmarking.
In theory, we could optimize this better by only flushing the TLB in
lazy CPUs when a page table is freed. Doing that would require
auditing the mm code to make sure that all page table freeing goes
through tlb_remove_page() as well as reworking some data structures
to implement the improved flush logic.
Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Reported-by: Adam Borowski <kilobyte@angband.pl>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Johannes Hirte <johannes.hirte@datenkhaos.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Roman Kagan <rkagan@virtuozzo.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 94b1b03b51 ("x86/mm: Rework lazy TLB mode and TLB freshness tracking")
Link: http://lkml.kernel.org/r/20171009170231.fkpraqokz6e4zeco@pd.tnic
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'for-linus-4.14c-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull xen fixlet from Juergen Gross:
"A minor fix correcting the cpu hotplug name for Xen guests"
* tag 'for-linus-4.14c-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
xen/vcpu: Use a unified name about cpu hotplug state for pv and pvhvm
Commit 594a30fb12 ("x86/apic: Silence "FW_BUG TSC_DEADLINE disabled
due to Errata" on CPUs without the feature", 2017-08-30) was also about
silencing the warning on VirtualBox; however, KVM does expose the TSC
deadline timer, and it's virtualized so that it is immune from CPU errata.
Therefore, booting 4.13 with "-cpu Haswell" shows this in the logs:
[ 0.000000] [Firmware Bug]: TSC_DEADLINE disabled due to Errata;
please update microcode to version: 0xb2 (or later)
Even if you had a hypervisor that does _not_ virtualize the TSC deadline
and rather exposes the hardware one, it should be the hypervisors task
to update microcode and possibly hide the flag from CPUID. So just
hide the message when running on _any_ hypervisor, not just those that
do not support the TSC deadline timer.
The older check still makes sense, so keep it.
Fixes: bd9240a18e ("x86/apic: Add TSC_DEADLINE quirk due to errata")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: kvm@vger.kernel.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1507630377-54471-1-git-send-email-pbonzini@redhat.com
When KVM emulates an exit from L2 to L1, it loads L1 CR4 into the
guest CR4. Before this CR4 loading, the guest CR4 refers to L2
CR4. Because these two CR4's are in different levels of guest, we
should vmx_set_cr4() rather than kvm_set_cr4() here. The latter, which
is used to handle guest writes to its CR4, checks the guest change to
CR4 and may fail if the change is invalid.
The failure may cause trouble. Consider we start
a L1 guest with non-zero L1 PCID in use,
(i.e. L1 CR4.PCIDE == 1 && L1 CR3.PCID != 0)
and
a L2 guest with L2 PCID disabled,
(i.e. L2 CR4.PCIDE == 0)
and following events may happen:
1. If kvm_set_cr4() is used in load_vmcs12_host_state() to load L1 CR4
into guest CR4 (in VMCS01) for L2 to L1 exit, it will fail because
of PCID check. As a result, the guest CR4 recorded in L0 KVM (i.e.
vcpu->arch.cr4) is left to the value of L2 CR4.
2. Later, if L1 attempts to change its CR4, e.g., clearing VMXE bit,
kvm_set_cr4() in L0 KVM will think L1 also wants to enable PCID,
because the wrong L2 CR4 is used by L0 KVM as L1 CR4. As L1
CR3.PCID != 0, L0 KVM will inject GP to L1 guest.
Fixes: 4704d0befb ("KVM: nVMX: Exiting from L2 to L1")
Cc: qemu-stable@nongnu.org
Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Increase testing coverage by turning on the primary x86 unwinder for
the 64-bit defconfig.
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: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Some routines in mem_encrypt.c are called very early in the boot process,
e.g. sme_enable(). When CONFIG_KCOV=y is defined the resulting code added
to sme_enable() (and others) for KCOV instrumentation results in a kernel
crash. Disable the KCOV instrumentation for mem_encrypt.c by adding
KCOV_INSTRUMENT_mem_encrypt.o := n to arch/x86/mm/Makefile.
In order to avoid other possible early boot issues, model mem_encrypt.c
after head64.c in regards to tools. In addition to disabling KCOV as
stated above and a previous patch that disables branch profiling, also
remove the "-pg" CFLAG if CONFIG_FUNCTION_TRACER is enabled and set
KASAN_SANITIZE to "n", each of which are done on a file basis.
Reported-by: kernel test robot <lkp@01.org>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Borislav Petkov <bp@alien8.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/20171010194504.18887.38053.stgit@tlendack-t1.amdoffice.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
is_last_gpte() is not equivalent to the pseudo-code given in commit
6bb69c9b69 ("KVM: MMU: simplify last_pte_bitmap") because an incorrect
value of last_nonleaf_level may override the result even if level == 1.
It is critical for is_last_gpte() to return true on level == 1 to
terminate page walks. Otherwise memory corruption may occur as level
is used as an index to various data structures throughout the page
walking code. Even though the actual bug would be wherever the MMU is
initialized (as in the previous patch), be defensive and ensure here
that is_last_gpte() returns the correct value.
This patch is also enough to fix CVE-2017-12188.
Fixes: 6bb69c9b69
Cc: stable@vger.kernel.org
Cc: Andy Honig <ahonig@google.com>
Signed-off-by: Ladi Prosek <lprosek@redhat.com>
[Panic if walk_addr_generic gets an incorrect level; this is a serious
bug and it's not worth a WARN_ON where the recovery path might hide
further exploitable issues; suggested by Andrew Honig. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The function updates context->root_level but didn't call
update_last_nonleaf_level so the previous and potentially wrong value
was used for page walks. For example, a zero value of last_nonleaf_level
would allow a potential out-of-bounds access in arch/x86/mmu/paging_tmpl.h's
walk_addr_generic function (CVE-2017-12188).
Fixes: 155a97a3d7
Signed-off-by: Ladi Prosek <lprosek@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
As xen_cpuhp_setup is called by PV and PVHVM, the name of "x86/xen/hvm_guest"
is confusing.
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Do not consider the fixed size of hv_vp_set when passing the variable
header size to hv_do_rep_hypercall().
The Hyper-V hypervisor specification states that for a hypercall with a
variable header only the size of the variable portion should be supplied
via the input control.
For HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX/LIST_EX calls that means the
fixed portion of hv_vp_set should not be considered.
That fixes random failures of some applications that are unexpectedly
killed with SIGBUS or SIGSEGV.
Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Jork Loeser <Jork.Loeser@microsoft.com>
Cc: Josh Poulson <jopoulso@microsoft.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Simon Xiao <sixiao@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: devel@linuxdriverproject.org
Fixes: 628f54cc64 ("x86/hyper-v: Support extended CPU ranges for TLB flush hypercalls")
Link: http://lkml.kernel.org/r/1507210469-29065-1-git-send-email-marcelo.cerri@canonical.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
hv_do_hypercall() does virt_to_phys() translation and with some configs
(CONFIG_SLAB) this doesn't work for percpu areas, we pass wrong memory to
hypervisor and get #GP. We could use working slow_virt_to_phys() instead
but doing so kills the performance.
Move pcpu_flush/pcpu_flush_ex structures out of percpu areas and
allocate memory on first call. The additional level of indirection gives
us a small performance penalty, in future we may consider introducing
hypercall functions which avoid virt_to_phys() conversion and cache
physical addresses of pcpu_flush/pcpu_flush_ex structures somewhere.
Reported-by: Simon Xiao <sixiao@microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Jork Loeser <Jork.Loeser@microsoft.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: devel@linuxdriverproject.org
Link: http://lkml.kernel.org/r/20171005113924.28021-1-vkuznets@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
hv_flush_pcpu_ex structures are not cleared between calls for performance
reasons (they're variable size up to PAGE_SIZE each) but we must clear
hv_vp_set.bank_contents part of it to avoid flushing unneeded vCPUs. The
rest of the structure is formed correctly.
To do the clearing in an efficient way stash the maximum possible vCPU
number (this may differ from Linux CPU id).
Reported-by: Jork Loeser <Jork.Loeser@microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: devel@linuxdriverproject.org
Link: http://lkml.kernel.org/r/20171006154854.18092-1-vkuznets@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently if an allocation fails then the error return paths
don't free up any currently allocated pmus[].boxes and pmus causing
a memory leak. Add an error clean up exit path that frees these
objects.
Detected by CoverityScan, CID#711632 ("Resource Leak")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-janitors@vger.kernel.org
Fixes: 087bfbb032 ("perf/x86: Add generic Intel uncore PMU support")
Link: http://lkml.kernel.org/r/20171009172655.6132-1-colin.king@canonical.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
x86-32 doesn't have stack validation, so in most cases it doesn't make
sense to warn about bad frame pointers.
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: LKP <lkp@01.org>
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/a69658760800bf281e6353248c23e0fa0acf5230.1507597785.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When printing the unwinder dump, the stack pointer could be unaligned,
for one of two reasons:
- stack corruption; or
- GCC created an unaligned stack.
There's no way for the unwinder to tell the difference between the two,
so we have to assume one or the other. GCC unaligned stacks are very
rare, and have only been spotted before GCC 5. Presumably, if we're
doing an unwinder stack dump, stack corruption is more likely than a
GCC unaligned stack. So always align the stack before starting the
dump.
Reported-and-tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-and-tested-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: LKP <lkp@01.org>
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/2f540c515946ab09ed267e1a1d6421202a0cce08.1507597785.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
On x86-32, Tetsuo Handa and Fengguang Wu reported unwinder warnings
like:
WARNING: kernel stack regs at f60bb9c8 in swapper:1 has bad 'bp' value 0ba00000
And also there were some stack dumps with a bunch of unreliable '?'
symbols after an apic_timer_interrupt symbol, meaning the unwinder got
confused when it tried to read the regs.
The cause of those issues is that, with GCC 4.8 (and possibly older),
there are cases where GCC misaligns the stack pointer in a leaf function
for no apparent reason:
c124a388 <acpi_rs_move_data>:
c124a388: 55 push %ebp
c124a389: 89 e5 mov %esp,%ebp
c124a38b: 57 push %edi
c124a38c: 56 push %esi
c124a38d: 89 d6 mov %edx,%esi
c124a38f: 53 push %ebx
c124a390: 31 db xor %ebx,%ebx
c124a392: 83 ec 03 sub $0x3,%esp
...
c124a3e3: 83 c4 03 add $0x3,%esp
c124a3e6: 5b pop %ebx
c124a3e7: 5e pop %esi
c124a3e8: 5f pop %edi
c124a3e9: 5d pop %ebp
c124a3ea: c3 ret
If an interrupt occurs in such a function, the regs on the stack will be
unaligned, which breaks the frame pointer encoding assumption. So on
32-bit, use the MSB instead of the LSB to encode the regs.
This isn't an issue on 64-bit, because interrupts align the stack before
writing to it.
Reported-and-tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-and-tested-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: LKP <lkp@01.org>
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/279a26996a482ca716605c7dbc7f2db9d8d91e81.1507597785.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The alt_max_short() macro in asm/alternative.h does not work as
intended, leading to nasty bugs. E.g. alt_max_short("1", "3")
evaluates to 3, but alt_max_short("3", "1") evaluates to 1 -- not
exactly the maximum of 1 and 3.
In fact, I had to learn it the hard way by crashing my kernel in not
so funny ways by attempting to make use of the ALTENATIVE_2 macro
with alternatives where the first one was larger than the second
one.
According to [1] and commit dbe4058a6a ("x86/alternatives: Fix
ALTERNATIVE_2 padding generation properly") the right handed side
should read "-(-(a < b))" not "-(-(a - b))". Fix that, to make the
macro work as intended.
While at it, fix up the comments regarding the additional "-", too.
It's not about gas' usage of s32 but brain dead logic of having a
"true" value of -1 for the < operator ... *sigh*
Btw., the one in asm/alternative-asm.h is correct. And, apparently,
all current users of ALTERNATIVE_2() pass same sized alternatives,
avoiding to hit the bug.
[1] http://graphics.stanford.edu/~seander/bithacks.html#IntegerMinOrMax
Reviewed-and-tested-by: Borislav Petkov <bp@suse.de>
Fixes: dbe4058a6a ("x86/alternatives: Fix ALTERNATIVE_2 padding generation properly")
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1507228213-13095-1-git-send-email-minipli@googlemail.com
Trying to reboot via real mode fails with PCID on: long mode cannot
be exited while CR4.PCIDE is set. (No, I have no idea why, but the
SDM and actual CPUs are in agreement here.) The result is a GPF and
a hang instead of a reboot.
I didn't catch this in testing because neither my computer nor my VM
reboots this way. I can trigger it with reboot=bios, though.
Fixes: 660da7c922 ("x86/mm: Enable CR4.PCIDE on supported systems")
Reported-and-tested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Link: https://lkml.kernel.org/r/f1e7d965998018450a7a70c2823873686a8b21c0.1507524746.git.luto@kernel.org
- fix PPC XIVE interrupt delivery
- fix x86 RCU breakage from asynchronous page faults when built without
PREEMPT_COUNT
- fix x86 build with -frecord-gcc-switches
- fix x86 build without X86_LOCAL_APIC
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM fixes from Radim Krčmář:
- fix PPC XIVE interrupt delivery
- fix x86 RCU breakage from asynchronous page faults when built without
PREEMPT_COUNT
- fix x86 build with -frecord-gcc-switches
- fix x86 build without X86_LOCAL_APIC
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: add X86_LOCAL_APIC dependency
x86/kvm: Move kvm_fastop_exception to .fixup section
kvm/x86: Avoid async PF preempting the kernel incorrectly
KVM: PPC: Book3S: Fix server always zero from kvmppc_xive_get_xive()
Pull watchddog clean-up and fixes from Thomas Gleixner:
"The watchdog (hard/softlockup detector) code is pretty much broken in
its current state. The patch series addresses this by removing all
duct tape and refactoring it into a workable state.
The reasons why I ask for inclusion that late in the cycle are:
1) The code causes lockdep splats vs. hotplug locking which get
reported over and over. Unfortunately there is no easy fix.
2) The risk of breakage is minimal because it's already broken
3) As 4.14 is a long term stable kernel, I prefer to have working
watchdog code in that and the lockdep issues resolved. I wouldn't
ask you to pull if 4.14 wouldn't be a LTS kernel or if the
solution would be easy to backport.
4) The series was around before the merge window opened, but then got
delayed due to the UP failure caused by the for_each_cpu()
surprise which we discussed recently.
Changes vs. V1:
- Addressed your review points
- Addressed the warning in the powerpc code which was discovered late
- Changed two function names which made sense up to a certain point
in the series. Now they match what they do in the end.
- Fixed a 'unused variable' warning, which got not detected by the
intel robot. I triggered it when trying all possible related config
combinations manually. Randconfig testing seems not random enough.
The changes have been tested by and reviewed by Don Zickus and tested
and acked by Micheal Ellerman for powerpc"
* 'core-watchdog-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits)
watchdog/core: Put softlockup_threads_initialized under ifdef guard
watchdog/core: Rename some softlockup_* functions
powerpc/watchdog: Make use of watchdog_nmi_probe()
watchdog/core, powerpc: Lock cpus across reconfiguration
watchdog/core, powerpc: Replace watchdog_nmi_reconfigure()
watchdog/hardlockup/perf: Fix spelling mistake: "permanetely" -> "permanently"
watchdog/hardlockup/perf: Cure UP damage
watchdog/hardlockup: Clean up hotplug locking mess
watchdog/hardlockup/perf: Simplify deferred event destroy
watchdog/hardlockup/perf: Use new perf CPU enable mechanism
watchdog/hardlockup/perf: Implement CPU enable replacement
watchdog/hardlockup/perf: Implement init time detection of perf
watchdog/hardlockup/perf: Implement init time perf validation
watchdog/core: Get rid of the racy update loop
watchdog/core, powerpc: Make watchdog_nmi_reconfigure() two stage
watchdog/sysctl: Clean up sysctl variable name space
watchdog/sysctl: Get rid of the #ifdeffery
watchdog/core: Clean up header mess
watchdog/core: Further simplify sysctl handling
watchdog/core: Get rid of the thread teardown/setup dance
...
The rework of the posted interrupt handling broke building without
support for the local APIC:
ERROR: "boot_cpu_physical_apicid" [arch/x86/kvm/kvm-intel.ko] undefined!
That configuration is probably not particularly useful anyway, so
we can avoid the randconfig failures by adding a Kconfig dependency.
Fixes: 8b306e2f3c ("KVM: VMX: avoid double list add with VT-d posted interrupts")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Pull networking fixes from David Miller:
1) Check iwlwifi 9000 reorder buffer out-of-space condition properly,
from Sara Sharon.
2) Fix RCU splat in qualcomm rmnet driver, from Subash Abhinov
Kasiviswanathan.
3) Fix session and tunnel release races in l2tp, from Guillaume Nault
and Sabrina Dubroca.
4) Fix endian bug in sctp_diag_dump(), from Dan Carpenter.
5) Several mlx5 driver fixes from the Mellanox folks (max flow counters
cap check, invalid memory access in IPoIB support, etc.)
6) tun_get_user() should bail if skb->len is zero, from Alexander
Potapenko.
7) Fix RCU lookups in inetpeer, from Eric Dumazet.
8) Fix locking in packet_do_bund().
9) Handle cb->start() error properly in netlink dump code, from Jason
A. Donenfeld.
10) Handle multicast properly in UDP socket early demux code. From Paolo
Abeni.
11) Several erspan bug fixes in ip_gre, from Xin Long.
12) Fix use-after-free in socket filter code, in order to handle the
fact that listener lock is no longer taken during the three-way TCP
handshake. From Eric Dumazet.
13) Fix infoleak in RTM_GETSTATS, from Nikolay Aleksandrov.
14) Fix tail call generation in x86-64 BPF JIT, from Alexei Starovoitov.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (77 commits)
net: 8021q: skip packets if the vlan is down
bpf: fix bpf_tail_call() x64 JIT
net: stmmac: dwmac-rk: Add RK3128 GMAC support
rndis_host: support Novatel Verizon USB730L
net: rtnetlink: fix info leak in RTM_GETSTATS call
socket, bpf: fix possible use after free
mlxsw: spectrum_router: Track RIF of IPIP next hops
mlxsw: spectrum_router: Move VRF refcounting
net: hns3: Fix an error handling path in 'hclge_rss_init_hw()'
net: mvpp2: Fix clock resource by adding an optional bus clock
r8152: add Linksys USB3GIGV1 id
l2tp: fix l2tp_eth module loading
ip_gre: erspan device should keep dst
ip_gre: set tunnel hlen properly in erspan_tunnel_init
ip_gre: check packet length and mtu correctly in erspan_xmit
ip_gre: get key from session_id correctly in erspan_rcv
tipc: use only positive error codes in messages
ppp: fix __percpu annotation
udp: perform source validation for mcast early demux
IPv4: early demux can return an error code
...
When compiling the kernel with the '-frecord-gcc-switches' flag, objtool
complains:
arch/x86/kvm/emulate.o: warning: objtool: .GCC.command.line+0x0: special: can't find new instruction
And also the kernel fails to link.
The problem is that the 'kvm_fastop_exception' code gets placed into the
throwaway '.GCC.command.line' section instead of '.text'.
Exception fixup code is conventionally placed in the '.fixup' section,
so put it there where it belongs.
Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Now that lguest is gone, put it in the internal header which should be
used only by MCA/RAS code.
Add missing header guards while at it.
No functional change.
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20171002092836.22971-3-bp@alien8.de
Currently, in PREEMPT_COUNT=n kernel, kvm_async_pf_task_wait() could call
schedule() to reschedule in some cases. This could result in
accidentally ending the current RCU read-side critical section early,
causing random memory corruption in the guest, or otherwise preempting
the currently running task inside between preempt_disable and
preempt_enable.
The difficulty to handle this well is because we don't know whether an
async PF delivered in a preemptible section or RCU read-side critical section
for PREEMPT_COUNT=n, since preempt_disable()/enable() and rcu_read_lock/unlock()
are both no-ops in that case.
To cure this, we treat any async PF interrupting a kernel context as one
that cannot be preempted, preventing kvm_async_pf_task_wait() from choosing
the schedule() path in that case.
To do so, a second parameter for kvm_async_pf_task_wait() is introduced,
so that we know whether it's called from a context interrupting the
kernel, and the parameter is set properly in all the callsites.
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
- bpf prog_array just like all other types of bpf array accepts 32-bit index.
Clarify that in the comment.
- fix x64 JIT of bpf_tail_call which was incorrectly loading 8 instead of 4 bytes
- tighten corresponding check in the interpreter to stay consistent
The JIT bug can be triggered after introduction of BPF_F_NUMA_NODE flag
in commit 96eabe7a40 in 4.14. Before that the map_flags would stay zero and
though JIT code is wrong it will check bounds correctly.
Hence two fixes tags. All other JITs don't have this problem.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Fixes: 96eabe7a40 ("bpf: Allow selecting numa node during map creation")
Fixes: b52f00e6a7 ("x86: bpf_jit: implement bpf_tail_call() helper")
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Jprobes actually don't need to disable IRQs while calling
handlers, because of how we specify the kernel interface in
Documentation/kprobes.txt:
-----
Probe handlers are run with preemption disabled. Depending on the
architecture and optimization state, handlers may also run with
interrupts disabled (e.g., kretprobe handlers and optimized kprobe
handlers run without interrupt disabled on x86/x86-64).
-----
So let's remove IRQ disabling from jprobes too.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/150701508194.32266.14458959863314097305.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Richard Weinberger saw an unwinder warning when running bcc's opensnoop:
WARNING: kernel stack frame pointer at ffff99ef4076bea0 in opensnoop:2008 has bad value 0000000000000008
unwind stack type:0 next_sp: (null) mask:0x2 graph_idx:0
...
ffff99ef4076be88: ffff99ef4076bea0 (0xffff99ef4076bea0)
ffff99ef4076be90: ffffffffac442721 (optimized_callback +0x81/0x90)
...
A lockdep stack trace was initiated from inside a kprobe handler, when
the unwinder noticed a bad frame pointer on the stack. The bad frame
pointer is related to the fact that the kprobe optprobe trampoline
doesn't save the frame pointer before calling into optimized_callback().
Reported-and-tested-by: Richard Weinberger <richard@sigma-star.at>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: David S . Miller <davem@davemloft.net>
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/7aef2f8ecd75c2f505ef9b80490412262cf4a44c.1507038547.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
