- Remove restrictions on PAI NNPA and crypto counters, enabling
concurrent per-task and system-wide sampling and counting events
- Switch to GENERIC_CPU_DEVICES by setting up the CPU present mask in
the architecture code and letting the generic code handle CPU bring-up
- Add support for the diag204 busy indication facility to prevent
undesirable blocking during hypervisor logical CPU utilization
queries. Implement results caching
- Improve the handling of Store Data SCLP events by suppressing
unnecessary warning, preventing buffer release in I/O during failures,
and adding timeout handling for Store Data requests to address potential
firmware issues
- Provide optimized __arch_hweight*() implementations
- Remove the unnecessary CPU KOBJ_CHANGE uevents generated during topology
updates, as they are unused and also not present on other architectures
- Cleanup atomic_ops, optimize __atomic_set() for small values and
__atomic_cmpxchg_bool() for compilers supporting flag output constraint
- Couple of cleanups for KVM:
- Move and improve KVM struct definitions for DAT tables from gaccess.c
to a new header
- Pass the asce as parameter to sie64a()
- Make the crdte() and cspg() page table handling wrappers return a
boolean to indicate success, like the other existing "compare and swap"
wrappers
- Add documentation for HWCAP flags
- Switch to obtaining total RAM pages from memblock instead of
totalram_pages() during mm init, to ensure correct calculation of zero
page size, when defer_init is enabled
- Refactor lowcore access and switch to using the get_lowcore() function
instead of the S390_lowcore macro
- Cleanups for PG_arch_1 and folio handling in UV and hugetlb code
- Add missing MODULE_DESCRIPTION() macros
- Fix VM_FAULT_HWPOISON handling in do_exception()
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Merge tag 's390-6.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull s390 updates from Vasily Gorbik:
- Remove restrictions on PAI NNPA and crypto counters, enabling
concurrent per-task and system-wide sampling and counting events
- Switch to GENERIC_CPU_DEVICES by setting up the CPU present mask in
the architecture code and letting the generic code handle CPU
bring-up
- Add support for the diag204 busy indication facility to prevent
undesirable blocking during hypervisor logical CPU utilization
queries. Implement results caching
- Improve the handling of Store Data SCLP events by suppressing
unnecessary warning, preventing buffer release in I/O during
failures, and adding timeout handling for Store Data requests to
address potential firmware issues
- Provide optimized __arch_hweight*() implementations
- Remove the unnecessary CPU KOBJ_CHANGE uevents generated during
topology updates, as they are unused and also not present on other
architectures
- Cleanup atomic_ops, optimize __atomic_set() for small values and
__atomic_cmpxchg_bool() for compilers supporting flag output
constraint
- Couple of cleanups for KVM:
- Move and improve KVM struct definitions for DAT tables from
gaccess.c to a new header
- Pass the asce as parameter to sie64a()
- Make the crdte() and cspg() page table handling wrappers return a
boolean to indicate success, like the other existing "compare and
swap" wrappers
- Add documentation for HWCAP flags
- Switch to obtaining total RAM pages from memblock instead of
totalram_pages() during mm init, to ensure correct calculation of
zero page size, when defer_init is enabled
- Refactor lowcore access and switch to using the get_lowcore()
function instead of the S390_lowcore macro
- Cleanups for PG_arch_1 and folio handling in UV and hugetlb code
- Add missing MODULE_DESCRIPTION() macros
- Fix VM_FAULT_HWPOISON handling in do_exception()
* tag 's390-6.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (54 commits)
s390/mm: Fix VM_FAULT_HWPOISON handling in do_exception()
s390/kvm: Move bitfields for dat tables
s390/entry: Pass the asce as parameter to sie64a()
s390/sthyi: Use cached data when diag is busy
s390/sthyi: Move diag operations
s390/hypfs_diag: Diag204 busy loop
s390/diag: Add busy-indication-facility requirements
s390/diag: Diag204 add busy return errno
s390/diag: Return errno's from diag204
s390/sclp: Diag204 busy indication facility detection
s390/atomic_ops: Make use of flag output constraint
s390/atomic_ops: Improve __atomic_set() for small values
s390/atomic_ops: Use symbolic names
s390/smp: Switch to GENERIC_CPU_DEVICES
s390/hwcaps: Add documentation for HWCAP flags
s390/pgtable: Make crdte() and cspg() return a value
s390/topology: Remove CPU KOBJ_CHANGE uevents
s390/sclp: Add timeout to Store Data requests
s390/sclp: Prevent release of buffer in I/O
s390/sclp: Suppress unnecessary Store Data warning
...
crst_table_free() used to work with NULL pointers before the conversion
to ptdescs. Since crst_table_free() can be called with a NULL pointer
(error handling in crst_table_upgrade() add an explicit check.
Also add the same check to base_crst_free() for consistency reasons.
In real life this should not happen, since order two GFP_KERNEL
allocations will not fail, unless FAIL_PAGE_ALLOC is enabled and used.
Reported-by: Yunseong Kim <yskelg@gmail.com>
Fixes: 6326c26c15 ("s390: convert various pgalloc functions to use ptdescs")
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Replace all S390_lowcore usages in arch/s390/ by get_lowcore().
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
After commit 6326c26c15 ("s390: convert various pgalloc functions to use
ptdescs"), there are still some positions that use page->{lru, index}
instead of ptdesc->{pt_list, pt_index}. In order to make the use of
ptdesc->{pt_list, pt_index} clearer, it would be better to convert them as
well.
[zhengqi.arch@bytedance.com: fix build failure]
Link: https://lkml.kernel.org/r/20240305072154.26168-1-zhengqi.arch@bytedance.com
Link: https://lkml.kernel.org/r/04beaf3255056ffe131a5ea595736066c1e84756.1709541697.git.zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Make pte_free_tlb() look similar to pXd_free_tlb() family
functions.
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
CRSTs always have size of four pages, while 2KB-size page tables
always occupy a single page. Use that information to distinguish
page tables from CRSTs.
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Cease using 4KB pages to host two 2KB PTEs. That greatly
simplifies the memory management code at the expense of
page tables memory footprint.
Instead of two PTEs per 4KB page use only upper half of
the parent page for a single PTE. With that the list of
half-used pages pgtable_list becomes unneeded.
Further, the upper byte of the parent page _refcount
counter does not need to be used for fragments tracking
and could be left alone.
Commit 8211dad627 ("s390: add pte_free_defer() for
pgtables sharing page") introduced the use of PageActive
flag to coordinate a deferred free with 2KB page table
fragments tracking. Since there is no tracking anymore,
there is no need for using PageActive flag.
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
In order to be usable for early boot code move the simple
arch_set_page_dat() function to header file, and add its counter-part
arch_set_page_nodat(). Also change the parameters, and the function name
slightly.
This is required since there aren't any struct pages available in early
boot code, and renaming of functions is done to make sure that all users
are converted to the new API.
Instead of a pointer to a struct page a virtual address is passed, and
instead of an order the number of pages for which the page state needs be
set.
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Commit 6326c26c15 ("s390: convert various pgalloc functions
to use ptdescs") missed to convert tlb_remove_table() into
tlb_remove_ptdesc() in few locations.
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
- Get rid of private VM_FAULT flags
- Add word-at-a-time implementation
- Add DCACHE_WORD_ACCESS support
- Cleanup control register handling
- Disallow CPU hotplug of CPU 0 to simplify its handling complexity,
following a similar restriction in x86
- Optimize pai crypto map allocation
- Update the list of crypto express EP11 coprocessor operation modes
- Fixes and improvements for secure guests AP pass-through
- Several fixes to address incorrect page marking for address translation
with the "cmma no-dat" feature, preventing potential incorrect guest
TLB flushes
- Fix early IPI handling
- Several virtual vs physical address confusion fixes
- Various small fixes and improvements all over the code
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Merge tag 's390-6.7-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull s390 updates from Vasily Gorbik:
- Get rid of private VM_FAULT flags
- Add word-at-a-time implementation
- Add DCACHE_WORD_ACCESS support
- Cleanup control register handling
- Disallow CPU hotplug of CPU 0 to simplify its handling complexity,
following a similar restriction in x86
- Optimize pai crypto map allocation
- Update the list of crypto express EP11 coprocessor operation modes
- Fixes and improvements for secure guests AP pass-through
- Several fixes to address incorrect page marking for address
translation with the "cmma no-dat" feature, preventing potential
incorrect guest TLB flushes
- Fix early IPI handling
- Several virtual vs physical address confusion fixes
- Various small fixes and improvements all over the code
* tag 's390-6.7-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (74 commits)
s390/cio: replace deprecated strncpy with strscpy
s390/sclp: replace deprecated strncpy with strtomem
s390/cio: fix virtual vs physical address confusion
s390/cio: export CMG value as decimal
s390: delete the unused store_prefix() function
s390/cmma: fix handling of swapper_pg_dir and invalid_pg_dir
s390/cmma: fix detection of DAT pages
s390/sclp: handle default case in sclp memory notifier
s390/pai_crypto: remove per-cpu variable assignement in event initialization
s390/pai: initialize event count once at initialization
s390/pai_crypto: use PERF_ATTACH_TASK define for per task detection
s390/mm: add missing arch_set_page_dat() call to gmap allocations
s390/mm: add missing arch_set_page_dat() call to vmem_crst_alloc()
s390/cmma: fix initial kernel address space page table walk
s390/diag: add missing virt_to_phys() translation to diag224()
s390/mm,fault: move VM_FAULT_ERROR handling to do_exception()
s390/mm,fault: remove VM_FAULT_BADMAP and VM_FAULT_BADACCESS
s390/mm,fault: remove VM_FAULT_SIGNAL
s390/mm,fault: remove VM_FAULT_BADCONTEXT
s390/mm,fault: simplify kfence fault handling
...
If the cmma no-dat feature is available all pages that are not used for
dynamic address translation are marked as "no-dat" with the ESSA
instruction. This information is visible to the hypervisor, so that the
hypervisor can optimize purging of guest TLB entries. This also means that
pages which are used for dynamic address translation must not be marked as
"no-dat", since the hypervisor may then incorrectly not purge guest TLB
entries.
Region, segment, and page tables allocated within the gmap code are
incorrectly marked as "no-dat", since an explicit call to
arch_set_page_dat() is missing, which would remove the "no-dat" mark.
In order to fix this add a new gmap_alloc_crst() function which should
be used to allocate region and segment tables, and which also calls
arch_set_page_dat().
Also add the arch_set_page_dat() call to page_table_alloc_pgste().
Cc: <stable@vger.kernel.org>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Remove unnecessary __GFP_HIGHMEM masking, which was introduced with
commit 6326c26c15 ("s390: convert various pgalloc functions to use
ptdescs"). Also remove a whitespace change which was introduced with
the same commit.
Link: https://lore.kernel.org/all/CAOzc2px-SFSnmjcPriiB3cm1fNj3+YC8S0VSp4t1QvDR0f4E2A@mail.gmail.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels) which will
reduce the overall build time size of the kernel and run time memory
bloat by ~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)
Remove the sentinel element from appldata_table, s390dbf_table,
topology_ctl_table, cmm_table and page_table_sysctl. Reduced the memory
allocation in appldata_register_ops by 1 effectively removing the
sentinel from ops->ctl_table.
This removal is safe because register_sysctl_sz and register_sysctl use
the array size in addition to checking for the sentinel.
Tested-by: Alexander Gordeev <agordeev@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Joel Granados <j.granados@samsung.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Convert all single control register usages of __local_ctl_load() and
__local_ctl_store() to local_ctl_load() and local_ctl_store().
This also requires to change the type of some struct lowcore members
from __u64 to unsigned long.
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Add local and system prefix to some functions to clarify they change
control register contents on either the local CPU or the on all CPUs.
This results in the following API:
Two defines which load and save multiple control registers.
The defines correlate with the following C prototypes:
void __local_ctl_load(unsigned long *, unsigned int cr_low, unsigned int cr_high);
void __local_ctl_store(unsigned long *, unsigned int cr_low, unsigned int cr_high);
Two functions which locally set or clear one bit for a specified
control register:
void local_ctl_set_bit(unsigned int cr, unsigned int bit);
void local_ctl_clear_bit(unsigned int cr, unsigned int bit);
Two functions which set or clear one bit for a specified control
register on all CPUs:
void system_ctl_set_bit(unsigned int cr, unsigned int bit);
void system_ctl_clear_bit(unsigend int cr, unsigned int bit);
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
As part of the conversions to replace pgtable constructor/destructors with
ptdesc equivalents, convert various page table functions to use ptdescs.
Some of the functions use the *get*page*() helper functions. Convert
these to use pagetable_alloc() and ptdesc_address() instead to help
standardize page tables further.
Link: https://lkml.kernel.org/r/20230807230513.102486-15-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Guo Ren <guoren@kernel.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Palmer Dabbelt <palmer@rivosinc.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add s390-specific pte_free_defer(), to free table page via call_rcu().
pte_free_defer() will be called inside khugepaged's retract_page_tables()
loop, where allocating extra memory cannot be relied upon. This precedes
the generic version to avoid build breakage from incompatible pgtable_t.
This version is more complicated than others: because s390 fits two 2K
page tables into one 4K page (so page->rcu_head must be shared between
both halves), and already uses page->lru (which page->rcu_head overlays)
to list any free halves; with clever management by page->_refcount bits.
Build upon the existing management, adjusted to follow a new rule: that a
page is never on the free list if pte_free_defer() was used on either half
(marked by PageActive). And for simplicity, delay calling RCU until both
halves are freed.
Not adding back unallocated fragments to the list in pte_free_defer() can
result in wasting some amount of memory for pagetables, depending on how
long the allocated fragment will stay in use. In practice, this effect is
expected to be insignificant, and not justify a far more complex approach,
which might allow to add the fragments back later in __tlb_remove_table(),
where we might not have a stable mm any more.
[hughd@google.com: Claudio finds warning on mm_has_pgste() more useful than on mm_alloc_pgste()]
Link: https://lkml.kernel.org/r/3bc095ba-a180-ce3b-82b1-2bfc64612f3@google.com
Link: https://lkml.kernel.org/r/94eccf5f-264c-8abe-4567-e77f4b4e14a@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Tested-by: Alexander Gordeev <agordeev@linux.ibm.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Make use of atomic_fetch_xor() instead of an atomic_cmpxchg() loop to
implement atomic_xor_bits() (aka atomic_xor_return()). This makes the C
code more readable and in addition generates better code, since for z196
and newer a single lax instruction is generated instead of a cmpxchg()
loop.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
There is no need to declare an extra tables to just create directory,
this can be easily be done with a prefix path with register_sysctl().
Simplify this registration.
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20230310234525.3986352-6-mcgrof@kernel.org
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Use CRST_ALLOC_ORDER to make it more obvious what the order means,
and also to be consistent with other code, e.g. the vmemmap code.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
When CONFIG_DEBUG_VM is defined check that pending remove
and tracking nibbles (bits 31-24 of the page refcount) are
cleared. Should the earlier stages of the page lifespan
have a race or logical error, such check could help in
exposing the issue.
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Explicitly encode immediate value of pending remove nibble
(bits 31-28) and tracking nibble (bits 27-24) of the page
refcount whenever these nibbles are tested or changed, for
better readability. Also, add some comments describing how
the fragments are handled.
Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
There is a race on concurrent 2KB-pgtables release paths when
both upper and lower halves of the containing parent page are
freed, one via page_table_free_rcu() + __tlb_remove_table(),
and the other via page_table_free(). The race might lead to a
corruption as result of remove of list item in page_table_free()
concurrently with __free_page() in __tlb_remove_table().
Let's assume first the lower and next the upper 2KB-pgtables are
freed from a page. Since both halves of the page are allocated
the tracking byte (bits 24-31 of the page _refcount) has value
of 0x03 initially:
CPU0 CPU1
---- ----
page_table_free_rcu() // lower half
{
// _refcount[31..24] == 0x03
...
atomic_xor_bits(&page->_refcount,
0x11U << (0 + 24));
// _refcount[31..24] <= 0x12
...
table = table | (1U << 0);
tlb_remove_table(tlb, table);
}
...
__tlb_remove_table()
{
// _refcount[31..24] == 0x12
mask = _table & 3;
// mask <= 0x01
...
page_table_free() // upper half
{
// _refcount[31..24] == 0x12
...
atomic_xor_bits(
&page->_refcount,
1U << (1 + 24));
// _refcount[31..24] <= 0x10
// mask <= 0x10
...
atomic_xor_bits(&page->_refcount,
mask << (4 + 24));
// _refcount[31..24] <= 0x00
// mask <= 0x00
...
if (mask != 0) // == false
break;
fallthrough;
...
if (mask & 3) // == false
...
else
__free_page(page); list_del(&page->lru);
^^^^^^^^^^^^^^^^^^ RACE! ^^^^^^^^^^^^^^^^^^^^^
} ...
}
The problem is page_table_free() releases the page as result of
lower nibble unset and __tlb_remove_table() observing zero too
early. With this update page_table_free() will use the similar
logic as page_table_free_rcu() + __tlb_remove_table(), and mark
the fragment as pending for removal in the upper nibble until
after the list_del().
In other words, the parent page is considered as unreferenced and
safe to release only when the lower nibble is cleared already and
unsetting a bit in upper nibble results in that nibble turned zero.
Cc: stable@vger.kernel.org
Suggested-by: Vlastimil Babka <vbabka@suse.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
After adding the missing __va()/__pa() calls to the base asce
functions there are even more casts in the code than before. Make the
code more readable by passing and using pointers to page tables,
instead of using unsigned values for the same purpose.
This allows to get rid of nearly all casts within the code.
Suggested-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
The base asce functions create/free page tables open-coded to make
sure that the returned asce and page tables do not make use of any
enhanced DAT features like e.g. large pages. This is required for some
I/O functions that use an asce, like e.g. some service call requests.
Handling of virtual vs physical addresses is missing; therefore add
that now.
Note: this currently doesn't fix a real bug, since virtual addresses
are indentical to physical ones.
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
The physical address of page tables is passed around and
used as virtual address in various locations.
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Remove set_fs support from s390. With doing this rework address space
handling and simplify it. As a result address spaces are now setup
like this:
CPU running in | %cr1 ASCE | %cr7 ASCE | %cr13 ASCE
----------------------------|-----------|-----------|-----------
user space | user | user | kernel
kernel, normal execution | kernel | user | kernel
kernel, kvm guest execution | gmap | user | kernel
To achieve this the getcpu vdso syscall is removed in order to avoid
secondary address mode and a separate vdso address space in for user
space. The getcpu vdso syscall will be implemented differently with a
subsequent patch.
The kernel accesses user space always via secondary address space.
This happens in different ways:
- with mvcos in home space mode and directly read/write to secondary
address space
- with mvcs/mvcp in primary space mode and copy from primary space to
secondary space or vice versa
- with e.g. cs in secondary space mode and access secondary space
Switching translation modes happens with sacf before and after
instructions which access user space, like before.
Lazy handling of control register reloading is removed in the hope to
make everything simpler, but at the cost of making kernel entry and
exit a bit slower. That is: on kernel entry the primary asce is always
changed to contain the kernel asce, and on kernel exit the primary
asce is changed again so it contains the user asce.
In kernel mode there is only one exception to the primary asce: when
kvm guests are executed the primary asce contains the gmap asce (which
describes the guest address space). The primary asce is reset to
kernel asce whenever kvm guest execution is interrupted, so that this
doesn't has to be taken into account for any user space accesses.
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This fixes CVE-2020-11884 which allows for a local kernel crash or
code execution.
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Merge tag 'cve-2020-11884' from emailed bundle
Pull s390 fix from Christian Borntraeger:
"Fix a race between page table upgrade and uaccess on s390.
This fixes CVE-2020-11884 which allows for a local kernel crash or
code execution"
* tag 'cve-2020-11884' from emailed bundle:
s390/mm: fix page table upgrade vs 2ndary address mode accesses
A page table upgrade in a kernel section that uses secondary address
mode will mess up the kernel instructions as follows:
Consider the following scenario: two threads are sharing memory.
On CPU1 thread 1 does e.g. strnlen_user(). That gets to
old_fs = enable_sacf_uaccess();
len = strnlen_user_srst(src, size);
and
" la %2,0(%1)\n"
" la %3,0(%0,%1)\n"
" slgr %0,%0\n"
" sacf 256\n"
"0: srst %3,%2\n"
in strnlen_user_srst(). At that point we are in secondary space mode,
control register 1 points to kernel page table and instruction fetching
happens via c1, rather than usual c13. Interrupts are not disabled, for
obvious reasons.
On CPU2 thread 2 does MAP_FIXED mmap(), forcing the upgrade of page table
from 3-level to e.g. 4-level one. We'd allocated new top-level table,
set it up and now we hit this:
notify = 1;
spin_unlock_bh(&mm->page_table_lock);
}
if (notify)
on_each_cpu(__crst_table_upgrade, mm, 0);
OK, we need to actually change over to use of new page table and we
need that to happen in all threads that are currently running. Which
happens to include the thread 1. IPI is delivered and we have
static void __crst_table_upgrade(void *arg)
{
struct mm_struct *mm = arg;
if (current->active_mm == mm)
set_user_asce(mm);
__tlb_flush_local();
}
run on CPU1. That does
static inline void set_user_asce(struct mm_struct *mm)
{
S390_lowcore.user_asce = mm->context.asce;
OK, user page table address updated...
__ctl_load(S390_lowcore.user_asce, 1, 1);
... and control register 1 set to it.
clear_cpu_flag(CIF_ASCE_PRIMARY);
}
IPI is run in home space mode, so it's fine - insns are fetched
using c13, which always points to kernel page table. But as soon
as we return from the interrupt, previous PSW is restored, putting
CPU1 back into secondary space mode, at which point we no longer
get the kernel instructions from the kernel mapping.
The fix is to only fixup the control registers that are currently in use
for user processes during the page table update. We must also disable
interrupts in enable_sacf_uaccess to synchronize the cr and
thread.mm_segment updates against the on_each-cpu.
Fixes: 0aaba41b58 ("s390: remove all code using the access register mode")
Cc: stable@vger.kernel.org # 4.15+
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
References: CVE-2020-11884
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
This update consolidates page table handling code. Because
there are hardly any 31-bit binaries left we do not need to
optimize for that.
No extra efforts are needed to ensure that a compat task does
not map anything above 2GB. The TASK_SIZE limit for 31-bit
tasks is 2GB already and the generic code does check that a
resulting map address would not surpass that limit.
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
There is a maximum of two new tables allocated on page table
upgrade. Because we know that a loop the current implementation
is based on could be unrolled with some improvements:
* upgrade from 3 to 5 levels happens in one go - without an
unnecessary re-take of page_table_lock in-between;
* page tables initialization moved out of the atomic code;
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
The naming of pgtable_page_{ctor,dtor}() seems to have confused a few
people, and until recently arm64 used these erroneously/pointlessly for
other levels of page table.
To make it incredibly clear that these only apply to the PTE level, and to
align with the naming of pgtable_pmd_page_{ctor,dtor}(), let's rename them
to pgtable_pte_page_{ctor,dtor}().
These changes were generated with the following shell script:
----
git grep -lw 'pgtable_page_.tor' | while read FILE; do
sed -i '{s/pgtable_page_ctor/pgtable_pte_page_ctor/}' $FILE;
sed -i '{s/pgtable_page_dtor/pgtable_pte_page_dtor/}' $FILE;
done
----
... with the documentation re-flowed to remain under 80 columns, and
whitespace fixed up in macros to keep backslashes aligned.
There should be no functional change as a result of this patch.
Link: http://lkml.kernel.org/r/20190722141133.3116-1-mark.rutland@arm.com
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> [m68k]
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit eec4844fae ("proc/sysctl: add shared variables for range
check") special shared variables are available for sysctl range check.
Reuse them for /proc/sys/vm/allocate_pgste proc handler.
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Pull RCU changes from Paul E. McKenney:
- Convert RCU's BUG_ON() and similar calls to WARN_ON() and similar.
- Replace calls of RCU-bh and RCU-sched update-side functions
to their vanilla RCU counterparts. This series is a step
towards complete removal of the RCU-bh and RCU-sched update-side
functions.
( Note that some of these conversions are going upstream via their
respective maintainers. )
- Documentation updates, including a number of flavor-consolidation
updates from Joel Fernandes.
- Miscellaneous fixes.
- Automate generation of the initrd filesystem used for
rcutorture testing.
- Convert spin_is_locked() assertions to instead use lockdep.
( Note that some of these conversions are going upstream via their
respective maintainers. )
- SRCU updates, especially including a fix from Dennis Krein
for a bag-on-head-class bug.
- RCU torture-test updates.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The downgrade of a page table from 3 levels to 2 levels for a 31-bit compat
process removes a pmd table which has to be counted against pgtable_bytes.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Now that call_rcu()'s callback is not invoked until after all
preempt-disable regions of code have completed (in addition to explicitly
marked RCU read-side critical sections), call_rcu() can be used in place
of call_rcu_sched(). This commit therefore makes that change.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: <linux-s390@vger.kernel.org>
In case a fork or a clone system fails in copy_process and the error
handling does the mmput() at the bad_fork_cleanup_mm label, the
following warning messages will appear on the console:
BUG: non-zero pgtables_bytes on freeing mm: 16384
The reason for that is the tricks we play with mm_inc_nr_puds() and
mm_inc_nr_pmds() in init_new_context().
A normal 64-bit process has 3 levels of page table, the p4d level and
the pud level are folded. On process termination the free_pud_range()
function in mm/memory.c will subtract 16KB from pgtable_bytes with a
mm_dec_nr_puds() call, but there actually is not really a pud table.
One issue with this is the fact that pgtable_bytes is usually off
by a few kilobytes, but the more severe problem is that for a failed
fork or clone the free_pgtables() function is not called. In this case
there is no mm_dec_nr_puds() or mm_dec_nr_pmds() that go together with
the mm_inc_nr_puds() and mm_inc_nr_pmds in init_new_context().
The pgtable_bytes will be off by 16384 or 32768 bytes and we get the
BUG message. The message itself is purely cosmetic, but annoying.
To fix this override the mm_pmd_folded, mm_pud_folded and mm_p4d_folded
function to check for the true size of the address space.
Reported-by: Li Wang <liwang@redhat.com>
Tested-by: Li Wang <liwang@redhat.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Pull s390 updates from Heiko Carstens:
"Since Martin is on vacation you get the s390 pull request from me:
- Host large page support for KVM guests. As the patches have large
impact on arch/s390/mm/ this series goes out via both the KVM and
the s390 tree.
- Add an option for no compression to the "Kernel compression mode"
menu, this will come in handy with the rework of the early boot
code.
- A large rework of the early boot code that will make life easier
for KASAN and KASLR. With the rework the bootable uncompressed
image is not generated anymore, only the bzImage is available. For
debuggung purposes the new "no compression" option is used.
- Re-enable the gcc plugins as the issue with the latent entropy
plugin is solved with the early boot code rework.
- More spectre relates changes:
+ Detect the etoken facility and remove expolines automatically.
+ Add expolines to a few more indirect branches.
- A rewrite of the common I/O layer trace points to make them
consumable by 'perf stat'.
- Add support for format-3 PCI function measurement blocks.
- Changes for the zcrypt driver:
+ Add attributes to indicate the load of cards and queues.
+ Restructure some code for the upcoming AP device support in KVM.
- Build flags improvements in various Makefiles.
- A few fixes for the kdump support.
- A couple of patches for gcc 8 compile warning cleanup.
- Cleanup s390 specific proc handlers.
- Add s390 support to the restartable sequence self tests.
- Some PTR_RET vs PTR_ERR_OR_ZERO cleanup.
- Lots of bug fixes"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (107 commits)
s390/dasd: fix hanging offline processing due to canceled worker
s390/dasd: fix panic for failed online processing
s390/mm: fix addressing exception after suspend/resume
rseq/selftests: add s390 support
s390: fix br_r1_trampoline for machines without exrl
s390/lib: use expoline for all bcr instructions
s390/numa: move initial setup of node_to_cpumask_map
s390/kdump: Fix elfcorehdr size calculation
s390/cpum_sf: save TOD clock base in SDBs for time conversion
KVM: s390: Add huge page enablement control
s390/mm: Add huge page gmap linking support
s390/mm: hugetlb pages within a gmap can not be freed
KVM: s390: Add skey emulation fault handling
s390/mm: Add huge pmd storage key handling
s390/mm: Clear skeys for newly mapped huge guest pmds
s390/mm: Clear huge page storage keys on enable_skey
s390/mm: Add huge page dirty sync support
s390/mm: Add gmap pmd invalidation and clearing
s390/mm: Add gmap pmd notification bit setting
s390/mm: Add gmap pmd linking
...
Since proc_dointvec does not perform value range control,
proc_dointvec_minmax should be used to limit value range, which is
clearly intended here, as the internal representation of the value:
unsigned int alloc_pgste:1;
In fact it currently works, since we have
mm->context.alloc_pgste = page_table_allocate_pgste || ...
... since commit 23fefe119c ("s390/kvm: avoid global config of vm.alloc_pgste=1")
Before that it was
mm->context.alloc_pgste = page_table_allocate_pgste;
which was broken. That was introduced with commit 0b46e0a3ec ("s390/kvm:
remove delayed reallocation of page tables for KVM").
Fixes: 0b46e0a3ec ("s390/kvm: remove delayed reallocation of page tables for KVM")
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
s390 no longer uses the _mapcount field in struct page to identify
the page table format being used. While the code was diligent in handling
the different mappings, it neglected to turn "off" the map bits when
alloc_pgste was being used. This resulted in bits remaining "on" in the
_refcount field, and thus an artifically huge "in use" count that prevents
the pages from actually being released by __free_page.
There's opportunity for improvement in the "1 vs 3" vs "1U vs 3U" vs
"0x1 vs 0x11" etc. variations for all these calls, I am just keeping
things simple compared to neighboring code.
Fixes: 620b4e9031 ("s390: use _refcount for pgtables")
Reported-by: Halil Pasic <pasic@linux.ibm.com>
Bisected-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Patch series "Rearrange struct page", v6.
As presented at LSFMM, this patch-set rearranges struct page to give
more contiguous usable space to users who have allocated a struct page
for their own purposes. For a graphical view of before-and-after, see
the first two tabs of
https://docs.google.com/spreadsheets/d/1tvCszs_7FXrjei9_mtFiKV6nW1FLnYyvPvW-qNZhdog/edit?usp=sharing
Highlights:
- deferred_list now really exists in struct page instead of just a comment.
- hmm_data also exists in struct page instead of being a nasty hack.
- x86's PGD pages have a real pointer to the mm_struct.
- VMalloc pages now have all sorts of extra information stored in them
to help with debugging and tuning.
- rcu_head is no longer tied to slab in case anyone else wants to
free pages by RCU.
- slub's counters no longer share space with _refcount.
- slub's freelist+counters are now naturally dword aligned.
- slub loses a parameter to a lot of functions and a sysfs file.
This patch (of 17):
s390 borrows the storage used for _mapcount in struct page in order to
account whether the bottom or top half is being used for 2kB page tables.
I want to use that for something else, so use the top byte of _refcount
instead of the bottom byte of _mapcount. _refcount may temporarily be
incremented by other CPUs that see a stale pointer to this page in the
page cache, but each CPU can only increment it by one, and there are no
systems with 2^24 CPUs today, so they will not change the upper byte of
_refcount. We do have to be a little careful not to lose any of their
writes (as they will subsequently decrement the counter).
Link: http://lkml.kernel.org/r/20180518194519.3820-2-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Provide base_asce_alloc() and base_asce_free() helper functions which
can be used to allocate an ASCE and all required region, segment and
page tables required to access memory regions of the virtual kernel
address space.
Both, the ASCE and all tables, do not use any features that correspond
to e.g. enhanced DAT features. This is required for some I/O functions
that pass an ASCE, like e.g. some service call requests, but which may
not use any enhanced features.
Acked-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Acked-by: Janosch Frank <frankja@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Martin Cermak reported that setting a uprobe doesn't work. Reason for
this is that the common uprobes code tries to get an unmapped area at
the last possible page within an address space.
This broke with commit 1aea9b3f92 ("s390/mm: implement 5 level pages
tables") which introduced an off-by-one bug which prevents to map
anything at the last possible page within an address space.
The check with the off-by-one bug however can be removed since with
commit 8ab867cb08 ("s390/mm: fix BUG_ON in crst_table_upgrade") the
necessary check is done at both call sites.
Reported-by: Martin Cermak <mcermak@redhat.com>
Bisected-by: Thomas Richter <tmricht@linux.vnet.ibm.com>
Fixes: 1aea9b3f92 ("s390/mm: implement 5 level pages tables")
Cc: <stable@vger.kernel.org> # v4.13+
Reviewed-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The vdso code for the getcpu() and the clock_gettime() call use the access
register mode to access the per-CPU vdso data page with the current code.
An alternative to the complicated AR mode is to use the secondary space
mode. This makes the vdso faster and quite a bit simpler. The downside is
that the uaccess code has to be changed quite a bit.
Which instructions are used depends on the machine and what kind of uaccess
operation is requested. The instruction dictates which ASCE value needs
to be loaded into %cr1 and %cr7.
The different cases:
* User copy with MVCOS for z10 and newer machines
The MVCOS instruction can copy between the primary space (aka user) and
the home space (aka kernel) directly. For set_fs(KERNEL_DS) the kernel
ASCE is loaded into %cr1. For set_fs(USER_DS) the user space is already
loaded in %cr1.
* User copy with MVCP/MVCS for older machines
To be able to execute the MVCP/MVCS instructions the kernel needs to
switch to primary mode. The control register %cr1 has to be set to the
kernel ASCE and %cr7 to either the kernel ASCE or the user ASCE dependent
on set_fs(KERNEL_DS) vs set_fs(USER_DS).
* Data access in the user address space for strnlen / futex
To use "normal" instruction with data from the user address space the
secondary space mode is used. The kernel needs to switch to primary mode,
%cr1 has to contain the kernel ASCE and %cr7 either the user ASCE or the
kernel ASCE, dependent on set_fs.
To load a new value into %cr1 or %cr7 is an expensive operation, the kernel
tries to be lazy about it. E.g. for multiple user copies in a row with
MVCP/MVCS the replacement of the vdso ASCE in %cr7 with the user ASCE is
done only once. On return to user space a CPU bit is checked that loads the
vdso ASCE again.
To enable and disable the data access via the secondary space two new
functions are added, enable_sacf_uaccess and disable_sacf_uaccess. The fact
that a context is in secondary space uaccess mode is stored in the
mm_segment_t value for the task. The code of an interrupt may use set_fs
as long as it returns to the previous state it got with get_fs with another
call to set_fs. The code in finish_arch_post_lock_switch simply has to do a
set_fs with the current mm_segment_t value for the task.
For CPUs with MVCOS:
CPU running in | %cr1 ASCE | %cr7 ASCE |
--------------------------------------|-----------|-----------|
user space | user | vdso |
kernel, USER_DS, normal-mode | user | vdso |
kernel, USER_DS, normal-mode, lazy | user | user |
kernel, USER_DS, sacf-mode | kernel | user |
kernel, KERNEL_DS, normal-mode | kernel | vdso |
kernel, KERNEL_DS, normal-mode, lazy | kernel | kernel |
kernel, KERNEL_DS, sacf-mode | kernel | kernel |
For CPUs without MVCOS:
CPU running in | %cr1 ASCE | %cr7 ASCE |
--------------------------------------|-----------|-----------|
user space | user | vdso |
kernel, USER_DS, normal-mode | user | vdso |
kernel, USER_DS, normal-mode lazy | kernel | user |
kernel, USER_DS, sacf-mode | kernel | user |
kernel, KERNEL_DS, normal-mode | kernel | vdso |
kernel, KERNEL_DS, normal-mode, lazy | kernel | kernel |
kernel, KERNEL_DS, sacf-mode | kernel | kernel |
The lines with "lazy" refer to the state after a copy via the secondary
space with a delayed reload of %cr1 and %cr7.
There are three hardware address spaces that can cause a DAT exception,
primary, secondary and home space. The exception can be related to
four different fault types: user space fault, vdso fault, kernel fault,
and the gmap faults.
Dependent on the set_fs state and normal vs. sacf mode there are a number
of fault combinations:
1) user address space fault via the primary ASCE
2) gmap address space fault via the primary ASCE
3) kernel address space fault via the primary ASCE for machines with
MVCOS and set_fs(KERNEL_DS)
4) vdso address space faults via the secondary ASCE with an invalid
address while running in secondary space in problem state
5) user address space fault via the secondary ASCE for user-copy
based on the secondary space mode, e.g. futex_ops or strnlen_user
6) kernel address space fault via the secondary ASCE for user-copy
with secondary space mode with set_fs(KERNEL_DS)
7) kernel address space fault via the primary ASCE for user-copy
with secondary space mode with set_fs(USER_DS) on machines without
MVCOS.
8) kernel address space fault via the home space ASCE
Replace user_space_fault() with a new function get_fault_type() that
can distinguish all four different fault types.
With these changes the futex atomic ops from the kernel and the
strnlen_user will get a little bit slower, as well as the old style
uaccess with MVCP/MVCS. All user accesses based on MVCOS will be as
fast as before. On the positive side, the user space vdso code is a
lot faster and Linux ceases to use the complicated AR mode.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Pull s390 updates from Heiko Carstens:
"Since Martin is on vacation you get the s390 pull request for the
v4.15 merge window this time from me.
Besides a lot of cleanups and bug fixes these are the most important
changes:
- a new regset for runtime instrumentation registers
- hardware accelerated AES-GCM support for the aes_s390 module
- support for the new CEX6S crypto cards
- support for FORTIFY_SOURCE
- addition of missing z13 and new z14 instructions to the in-kernel
disassembler
- generate opcode tables for the in-kernel disassembler out of a
simple text file instead of having to manually maintain those
tables
- fast memset16, memset32 and memset64 implementations
- removal of named saved segment support
- hardware counter support for z14
- queued spinlocks and queued rwlocks implementations for s390
- use the stack_depth tracking feature for s390 BPF JIT
- a new s390_sthyi system call which emulates the sthyi (store
hypervisor information) instruction
- removal of the old KVM virtio transport
- an s390 specific CPU alternatives implementation which is used in
the new spinlock code"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (88 commits)
MAINTAINERS: add virtio-ccw.h to virtio/s390 section
s390/noexec: execute kexec datamover without DAT
s390: fix transactional execution control register handling
s390/bpf: take advantage of stack_depth tracking
s390: simplify transactional execution elf hwcap handling
s390/zcrypt: Rework struct ap_qact_ap_info.
s390/virtio: remove unused header file kvm_virtio.h
s390: avoid undefined behaviour
s390/disassembler: generate opcode tables from text file
s390/disassembler: remove insn_to_mnemonic()
s390/dasd: avoid calling do_gettimeofday()
s390: vfio-ccw: Do not attempt to free no-op, test and tic cda.
s390: remove named saved segment support
s390/archrandom: Reconsider s390 arch random implementation
s390/pci: do not require AIS facility
s390/qdio: sanitize put_indicator
s390/qdio: use atomic_cmpxchg
s390/nmi: avoid using long-displacement facility
s390: pass endianness info to sparse
s390/decompressor: remove informational messages
...
