970 Commits
Author SHA1 Message Date
Linus Torvalds fdcbb1bc06 Merge branch 'nocache-cleanup'
This series cleans up some of the special user copy functions naming and
semantics.  In particular, get rid of the (very traditional) double
underscore names and behavior: the whole "optimize away the range check"
model has been largely excised from the other user accessors because
it's so subtle and can be unsafe, but also because it's just not a
relevant optimization any more.

To do that, a couple of drivers that misused the "user" copies as kernel
copies in order to get non-temporal stores had to be fixed up, but that
kind of code should never have been allowed anyway.

The x86-only "nocache" version was also renamed to more accurately
reflect what it actually does.

This was all done because I looked at this code due to a report by Jann
Horn, and I just couldn't stand the inconsistent naming, the horrible
semantics, and the random misuse of these functions.  This code should
probably be cleaned up further, but it's at least slightly closer to
normal semantics.

I had a more intrusive series that went even further in trying to
normalize the semantics, but that ended up hitting so many other
inconsistencies between different architectures in this area (eg
'size_t' vs 'unsigned long' vs 'int' as size arguments, and various
iovec check differences that Vasily Gorbik pointed out) that I ended up
with this more limited version that fixed the worst of the issues.

Reported-by: Jann Horn <jannh@google.com>
Tested-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/all/CAHk-=wgg1QVWNWG-UCFo1hx0zqrPnB3qhPzUTrWNft+MtXQXig@mail.gmail.com/

* nocache-cleanup:
  x86-64/arm64/powerpc: clean up and rename __copy_from_user_flushcache
  x86: rename and clean up __copy_from_user_inatomic_nocache()
  x86-64: rename misleadingly named '__copy_user_nocache()' function
2026-04-13 08:39:51 -07:00
Linus Torvalds 809b997a5c x86-64/arm64/powerpc: clean up and rename __copy_from_user_flushcache
This finishes the work on these odd functions that were only implemented
by a handful of architectures.

The 'flushcache' function was only used from the iterator code, and
let's make it do the same thing that the nontemporal version does:
remove the two underscores and add the user address checking.

Yes, yes, the user address checking is also done at iovec import time,
but we have long since walked away from the old double-underscore thing
where we try to avoid address checking overhead at access time, and
these functions shouldn't be so special and old-fashioned.

The arm64 version already did the address check, in fact, so there it's
just a matter of renaming it.  For powerpc and x86-64 we now do the
proper user access boilerplate.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2026-03-30 15:05:57 -07:00
Linus Torvalds 5de7bcaadf x86: rename and clean up __copy_from_user_inatomic_nocache()
Similarly to the previous commit, this renames the somewhat confusingly
named function.  But in this case, it was at least less confusing: the
__copy_from_user_inatomic_nocache is indeed copying from user memory,
and it is indeed ok to be used in an atomic context, so it will not warn
about it.

But the previous commit also removed the NTB mis-use of the
__copy_from_user_inatomic_nocache() function, and as a result every
call-site is now _actually_ doing a real user copy.  That means that we
can now do the proper user pointer verification too.

End result: add proper address checking, remove the double underscores,
and change the "nocache" to "nontemporal" to more accurately describe
what this x86-only function actually does.  It might be worth noting
that only the target is non-temporal: the actual user accesses are
normal memory accesses.

Also worth noting is that non-x86 targets (and on older 32-bit x86 CPU's
before XMM2 in the Pentium III) we end up just falling back on a regular
user copy, so nothing can actually depend on the non-temporal semantics,
but that has always been true.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2026-03-30 15:05:57 -07:00
Linus Torvalds d187a86de7 x86-64: rename misleadingly named '__copy_user_nocache()' function
This function was a masterclass in bad naming, for various historical
reasons.

It claimed to be a non-cached user copy.  It is literally _neither_ of
those things.  It's a specialty memory copy routine that uses
non-temporal stores for the destination (but not the source), and that
does exception handling for both source and destination accesses.

Also note that while it works for unaligned targets, any unaligned parts
(whether at beginning or end) will not use non-temporal stores, since
only words and quadwords can be non-temporal on x86.

The exception handling means that it _can_ be used for user space
accesses, but not on its own - it needs all the normal "start user space
access" logic around it.

But typically the user space access would be the source, not the
non-temporal destination.  That was the original intention of this,
where the destination was some fragile persistent memory target that
needed non-temporal stores in order to catch machine check exceptions
synchronously and deal with them gracefully.

Thus that non-descriptive name: one use case was to copy from user space
into a non-cached kernel buffer.  However, the existing users are a mix
of that intended use-case, and a couple of random drivers that just did
this as a performance tweak.

Some of those random drivers then actively misused the user copying
version (with STAC/CLAC and all) to do kernel copies without ever even
caring about the exception handling, _just_ for the non-temporal
destination.

Rename it as a first small step to actually make it halfway sane, and
change the prototype to be more normal: it doesn't take a user pointer
unless the caller has done the proper conversion, and the argument size
is the full size_t (it still won't actually copy more than 4GB in one
go, but there's also no reason to silently truncate the size argument in
the caller).

Finally, use this now sanely named function in the NTB code, which
mis-used a user copy version (with STAC/CLAC and all) of this interface
despite it not actually being a user copy at all.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2026-03-30 15:05:56 -07:00
Linus Torvalds 4cff5c05e0 Merge tag 'mm-stable-2026-02-11-19-22' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:

 - "powerpc/64s: do not re-activate batched TLB flush" makes
   arch_{enter|leave}_lazy_mmu_mode() nest properly (Alexander Gordeev)

   It adds a generic enter/leave layer and switches architectures to use
   it. Various hacks were removed in the process.

 - "zram: introduce compressed data writeback" implements data
   compression for zram writeback (Richard Chang and Sergey Senozhatsky)

 - "mm: folio_zero_user: clear page ranges" adds clearing of contiguous
   page ranges for hugepages. Large improvements during demand faulting
   are demonstrated (David Hildenbrand)

 - "memcg cleanups" tidies up some memcg code (Chen Ridong)

 - "mm/damon: introduce {,max_}nr_snapshots and tracepoint for damos
   stats" improves DAMOS stat's provided information, deterministic
   control, and readability (SeongJae Park)

 - "selftests/mm: hugetlb cgroup charging: robustness fixes" fixes a few
   issues in the hugetlb cgroup charging selftests (Li Wang)

 - "Fix va_high_addr_switch.sh test failure - again" addresses several
   issues in the va_high_addr_switch test (Chunyu Hu)

 - "mm/damon/tests/core-kunit: extend existing test scenarios" improves
   the KUnit test coverage for DAMON (Shu Anzai)

 - "mm/khugepaged: fix dirty page handling for MADV_COLLAPSE" fixes a
   glitch in khugepaged which was causing madvise(MADV_COLLAPSE) to
   transiently return -EAGAIN (Shivank Garg)

 - "arch, mm: consolidate hugetlb early reservation" reworks and
   consolidates a pile of straggly code related to reservation of
   hugetlb memory from bootmem and creation of CMA areas for hugetlb
   (Mike Rapoport)

 - "mm: clean up anon_vma implementation" cleans up the anon_vma
   implementation in various ways (Lorenzo Stoakes)

 - "tweaks for __alloc_pages_slowpath()" does a little streamlining of
   the page allocator's slowpath code (Vlastimil Babka)

 - "memcg: separate private and public ID namespaces" cleans up the
   memcg ID code and prevents the internal-only private IDs from being
   exposed to userspace (Shakeel Butt)

 - "mm: hugetlb: allocate frozen gigantic folio" cleans up the
   allocation of frozen folios and avoids some atomic refcount
   operations (Kefeng Wang)

 - "mm/damon: advance DAMOS-based LRU sorting" improves DAMOS's movement
   of memory betewwn the active and inactive LRUs and adds auto-tuning
   of the ratio-based quotas and of monitoring intervals (SeongJae Park)

 - "Support page table check on PowerPC" makes
   CONFIG_PAGE_TABLE_CHECK_ENFORCED work on powerpc (Andrew Donnellan)

 - "nodemask: align nodes_and{,not} with underlying bitmap ops" makes
   nodes_and() and nodes_andnot() propagate the return values from the
   underlying bit operations, enabling some cleanup in calling code
   (Yury Norov)

 - "mm/damon: hide kdamond and kdamond_lock from API callers" cleans up
   some DAMON internal interfaces (SeongJae Park)

 - "mm/khugepaged: cleanups and scan limit fix" does some cleanup work
   in khupaged and fixes a scan limit accounting issue (Shivank Garg)

 - "mm: balloon infrastructure cleanups" goes to town on the balloon
   infrastructure and its page migration function. Mainly cleanups, also
   some locking simplification (David Hildenbrand)

 - "mm/vmscan: add tracepoint and reason for kswapd_failures reset" adds
   additional tracepoints to the page reclaim code (Jiayuan Chen)

 - "Replace wq users and add WQ_PERCPU to alloc_workqueue() users" is
   part of Marco's kernel-wide migration from the legacy workqueue APIs
   over to the preferred unbound workqueues (Marco Crivellari)

 - "Various mm kselftests improvements/fixes" provides various unrelated
   improvements/fixes for the mm kselftests (Kevin Brodsky)

 - "mm: accelerate gigantic folio allocation" greatly speeds up gigantic
   folio allocation, mainly by avoiding unnecessary work in
   pfn_range_valid_contig() (Kefeng Wang)

 - "selftests/damon: improve leak detection and wss estimation
   reliability" improves the reliability of two of the DAMON selftests
   (SeongJae Park)

 - "mm/damon: cleanup kdamond, damon_call(), damos filter and
   DAMON_MIN_REGION" does some cleanup work in the core DAMON code
   (SeongJae Park)

 - "Docs/mm/damon: update intro, modules, maintainer profile, and misc"
   performs maintenance work on the DAMON documentation (SeongJae Park)

 - "mm: add and use vma_assert_stabilised() helper" refactors and cleans
   up the core VMA code. The main aim here is to be able to use the mmap
   write lock's lockdep state to perform various assertions regarding
   the locking which the VMA code requires (Lorenzo Stoakes)

 - "mm, swap: swap table phase II: unify swapin use" removes some old
   swap code (swap cache bypassing and swap synchronization) which
   wasn't working very well. Various other cleanups and simplifications
   were made. The end result is a 20% speedup in one benchmark (Kairui
   Song)

 - "enable PT_RECLAIM on more 64-bit architectures" makes PT_RECLAIM
   available on 64-bit alpha, loongarch, mips, parisc, and um. Various
   cleanups were performed along the way (Qi Zheng)

* tag 'mm-stable-2026-02-11-19-22' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (325 commits)
  mm/memory: handle non-split locks correctly in zap_empty_pte_table()
  mm: move pte table reclaim code to memory.c
  mm: make PT_RECLAIM depends on MMU_GATHER_RCU_TABLE_FREE
  mm: convert __HAVE_ARCH_TLB_REMOVE_TABLE to CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE config
  um: mm: enable MMU_GATHER_RCU_TABLE_FREE
  parisc: mm: enable MMU_GATHER_RCU_TABLE_FREE
  mips: mm: enable MMU_GATHER_RCU_TABLE_FREE
  LoongArch: mm: enable MMU_GATHER_RCU_TABLE_FREE
  alpha: mm: enable MMU_GATHER_RCU_TABLE_FREE
  mm: change mm/pt_reclaim.c to use asm/tlb.h instead of asm-generic/tlb.h
  mm/damon/stat: remove __read_mostly from memory_idle_ms_percentiles
  zsmalloc: make common caches global
  mm: add SPDX id lines to some mm source files
  mm/zswap: use %pe to print error pointers
  mm/vmscan: use %pe to print error pointers
  mm/readahead: fix typo in comment
  mm: khugepaged: fix NR_FILE_PAGES and NR_SHMEM in collapse_file()
  mm: refactor vma_map_pages to use vm_insert_pages
  mm/damon: unify address range representation with damon_addr_range
  mm/cma: replace snprintf with strscpy in cma_new_area
  ...
2026-02-12 11:32:37 -08:00
Linus Torvalds 45a1b8cc6c Merge tag 'x86_misc_for_7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull misc x86 updates from Dave Hansen:
 "The usual smattering of x86/misc changes.

  The IPv6 patch in here surprised me in a couple of ways. First, the
  function it inlines is able to eat a lot more CPU time than I would
  have expected. Second, the inlining does not seem to bloat the kernel,
  at least in the configs folks have tested.

   - Inline x86-specific IPv6 checksum helper

   - Update IOMMU docs to use stable identifiers

   - Print unhashed pointers on fatal stack overflows"

* tag 'x86_misc_for_7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/traps: Print unhashed pointers on stack overflow
  Documentation/x86: Update IOMMU spec references to use stable identifiers
  x86/lib: Inline csum_ipv6_magic()
2026-02-10 19:52:18 -08:00
Ankur AroraandAndrew Morton 54a6b89a3d x86/mm: simplify clear_page_*
clear_page_rep() and clear_page_erms() are wrappers around "REP; STOS"
variations.  Inlining gets rid of an unnecessary CALL/RET (which isn't
free when using RETHUNK speculative execution mitigations.) Fixup and
rename clear_page_orig() to adapt to the changed calling convention.

Also add a comment from Dave Hansen detailing various clearing mechanisms
used in clear_page().

Link: https://lkml.kernel.org/r/20260107072009.1615991-5-ankur.a.arora@oracle.com
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
Tested-by: Raghavendra K T <raghavendra.kt@amd.com>
Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Konrad Rzessutek Wilk <konrad.wilk@oracle.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Li Zhe <lizhe.67@bytedance.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-01-20 19:24:40 -08:00
Juergen GrossandBorislav Petkov (AMD) 07f2961235 x86/paravirt: Remove not needed includes of paravirt.h
In some places asm/paravirt.h is included without really being needed.

Remove the related #include statements.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260105110520.21356-2-jgross@suse.com
2026-01-12 11:26:52 +01:00
Eric DumazetandDave Hansen 529676cabc x86/lib: Inline csum_ipv6_magic()
Inline this small helper. It has been observed to consume up
to 0.75%, which is significant for such a small function.

This should reduce register pressure, as saddr and daddr are often
back to back in memory.

For instance code inlined in tcp6_gro_receive() will look like:

 55a:	48 03 73 28          	add    0x28(%rbx),%rsi
 55e:	8b 43 70             	mov    0x70(%rbx),%eax
 561:	29 f8                	sub    %edi,%eax
 563:	0f c8                	bswap  %eax
 565:	89 c0                	mov    %eax,%eax
 567:	48 05 00 06 00 00    	add    $0x600,%rax
 56d:	48 03 46 08          	add    0x8(%rsi),%rax
 571:	48 13 46 10          	adc    0x10(%rsi),%rax
 575:	48 13 46 18          	adc    0x18(%rsi),%rax
 579:	48 13 46 20          	adc    0x20(%rsi),%rax
 57d:	48 83 d0 00          	adc    $0x0,%rax
 581:	48 89 c6             	mov    %rax,%rsi
 584:	48 c1 ee 20          	shr    $0x20,%rsi
 588:	01 f0                	add    %esi,%eax
 58a:	83 d0 00             	adc    $0x0,%eax
 58d:	89 c6                	mov    %eax,%esi
 58f:	66 31 c0             	xor    %ax,%ax

Surprisingly, this inlining does not seem to bloat kernel text size.
It at least two cases[1], it either has no effect or results in a
slightly smaller kernel.

1. https://lore.kernel.org/all/CANn89iJzcb_XO9oCApKYfRxsMMmg7BHukRDqWTca3ZLQ8HT0iQ@mail.gmail.com/

[ dhansen: add justification and note about lack of kernel bloat ]

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://patch.msgid.link/20251113154545.594580-1-edumazet@google.com
2026-01-05 10:14:05 -08:00
Linus Torvalds 08b8ddac1f Merge tag 'objtool-urgent-2025-12-06' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool fixes from Ingo Molnar:
 "Address various objtool scalability bugs/inefficiencies exposed by
  allmodconfig builds, plus improve the quality of alternatives
  instructions generated code and disassembly"

* tag 'objtool-urgent-2025-12-06' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Simplify .annotate_insn code generation output some more
  objtool: Add more robust signal error handling, detect and warn about stack overflows
  objtool: Remove newlines and tabs from annotation macros
  objtool: Consolidate annotation macros
  x86/asm: Remove ANNOTATE_DATA_SPECIAL usage
  x86/alternative: Remove ANNOTATE_DATA_SPECIAL usage
  objtool: Fix stack overflow in validate_branch()
2025-12-06 11:56:51 -08:00
Josh PoimboeufandIngo Molnar ed3bf863dc objtool: Remove newlines and tabs from annotation macros
Remove newlines and tabs from the annotation macros so the invoking code
can insert them as needed to match the style of the surrounding code.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://patch.msgid.link/66305834c2eb78f082217611b756231ae9c0b555.1764694625.git.jpoimboe@kernel.org
2025-12-03 19:42:37 +01:00
Linus Torvalds e2aa39b368 Merge tag 'x86_misc_for_6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull misc x86 updates from Dave Hansen:
 "The most significant are some changes to ensure that symbols exported
  for KVM are used only by KVM modules themselves, along with some
  related cleanups.

  In true x86/misc fashion, the other patch is completely unrelated and
  just enhances an existing pr_warn() to make it clear to users how they
  have tainted their kernel when something is mucking with MSRs.

  Summary:

   - Make MSR-induced taint easier for users to track down

   - Restrict KVM-specific exports to KVM itself"

* tag 'x86_misc_for_6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86: Restrict KVM-induced symbol exports to KVM modules where obvious/possible
  x86/mm: Drop unnecessary export of "ptdump_walk_pgd_level_debugfs"
  x86/mtrr: Drop unnecessary export of "mtrr_state"
  x86/bugs: Drop unnecessary export of "x86_spec_ctrl_base"
  x86/msr: Add CPU_OUT_OF_SPEC taint name to "unrecognized" pr_warn(msg)
2025-12-02 14:16:42 -08:00
Linus Torvalds cb502f0e5e Merge tag 'x86_sev_for_v6.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 SEV updates from Borislav Petkov:

 - Largely cleanups along with a change to save XSS to the GHCB
   (Guest-Host Communication Block) in SEV-ES guests so that the
   hypervisor can determine the guest's XSAVES buffer size properly
   and thus support shadow stacks in AMD confidential guests

* tag 'x86_sev_for_v6.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/cc: Fix enum spelling to fix kernel-doc warnings
  x86/boot: Drop unused sev_enable() fallback
  x86/coco/sev: Convert has_cpuflag() to use cpu_feature_enabled()
  x86/sev: Include XSS value in GHCB CPUID request
  x86/boot: Move boot_*msr helpers to asm/shared/msr.h
2025-12-02 13:07:53 -08:00
Sean ChristophersonandDave Hansen 6276c67f2b x86: Restrict KVM-induced symbol exports to KVM modules where obvious/possible
Extend KVM's export macro framework to provide EXPORT_SYMBOL_FOR_KVM(),
and use the helper macro to export symbols for KVM throughout x86 if and
only if KVM will build one or more modules, and only for those modules.

To avoid unnecessary exports when CONFIG_KVM=m but kvm.ko will not be
built (because no vendor modules are selected), let arch code #define
EXPORT_SYMBOL_FOR_KVM to suppress/override the exports.

Note, the set of symbols to restrict to KVM was generated by manual search
and audit; any "misses" are due to human error, not some grand plan.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Kai Huang <kai.huang@intel.com>
Tested-by: Kai Huang <kai.huang@intel.com>
Link: https://patch.msgid.link/20251112173944.1380633-5-seanjc%40google.com
2025-11-12 15:29:38 -08:00
Borislav Petkov (AMD) b2c1dd6c6f x86/coco/sev: Convert has_cpuflag() to use cpu_feature_enabled()
Drop one redundant definition, while at it.

There should be no functional changes.

Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://patch.msgid.link/20251031122122.GKaQSpwhLvkinKKbjG@fat_crate.local
2025-11-11 16:42:31 +01:00
Peter Zijlstra 45e1dccc06 x86/insn: Simplify for_each_insn_prefix()
Use the new-found freedom of allowing variable declarions inside
for() to simplify the for_each_insn_prefix() iterator to no longer
need an external temporary.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2025-10-16 11:13:48 +02:00
Peter Zijlstra 8a5c6cbfe4 x86/insn,uprobes,alternative: Unify insn_is_nop()
Both uprobes and alternatives have insn_is_nop() variants, unify them
and make sure insn_is_nop() works for both x86_64 and i386.

Specifically, uprobe must not compare userspace instructions to kernel
nops as that does not work right in the compat case.

For the uprobe case we therefore must recognise common 32bit and 64bit
nops. Because uprobe will consume the instruction as a nop, it must
not mistakenly claim a non-nop instruction to be a nop. Eg. 'REX.b3
NOP' is 'xchg %r8,%rax' - not a nop.

For the kernel case similar constraints apply, is it used to optimize
NOPs by replacing strings of short(er) nops with longer nops. Must not
claim an instruction is a nop if it really isn't. Not recognising a
nop is non-fatal.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2025-10-16 11:13:47 +02:00
Linus Torvalds 9591fdb061 Merge tag 'x86_core_for_v6.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull more x86 updates from Borislav Petkov:

 - Remove a bunch of asm implementing condition flags testing in KVM's
   emulator in favor of int3_emulate_jcc() which is written in C

 - Replace KVM fastops with C-based stubs which avoids problems with the
   fastop infra related to latter not adhering to the C ABI due to their
   special calling convention and, more importantly, bypassing compiler
   control-flow integrity checking because they're written in asm

 - Remove wrongly used static branches and other ugliness accumulated
   over time in hyperv's hypercall implementation with a proper static
   function call to the correct hypervisor call variant

 - Add some fixes and modifications to allow running FRED-enabled
   kernels in KVM even on non-FRED hardware

 - Add kCFI improvements like validating indirect calls and prepare for
   enabling kCFI with GCC. Add cmdline params documentation and other
   code cleanups

 - Use the single-byte 0xd6 insn as the official #UD single-byte
   undefined opcode instruction as agreed upon by both x86 vendors

 - Other smaller cleanups and touchups all over the place

* tag 'x86_core_for_v6.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
  x86,retpoline: Optimize patch_retpoline()
  x86,ibt: Use UDB instead of 0xEA
  x86/cfi: Remove __noinitretpoline and __noretpoline
  x86/cfi: Add "debug" option to "cfi=" bootparam
  x86/cfi: Standardize on common "CFI:" prefix for CFI reports
  x86/cfi: Document the "cfi=" bootparam options
  x86/traps: Clarify KCFI instruction layout
  compiler_types.h: Move __nocfi out of compiler-specific header
  objtool: Validate kCFI calls
  x86/fred: KVM: VMX: Always use FRED for IRQs when CONFIG_X86_FRED=y
  x86/fred: Play nice with invoking asm_fred_entry_from_kvm() on non-FRED hardware
  x86/fred: Install system vector handlers even if FRED isn't fully enabled
  x86/hyperv: Use direct call to hypercall-page
  x86/hyperv: Clean up hv_do_hypercall()
  KVM: x86: Remove fastops
  KVM: x86: Convert em_salc() to C
  KVM: x86: Introduce EM_ASM_3WCL
  KVM: x86: Introduce EM_ASM_1SRC2
  KVM: x86: Introduce EM_ASM_2CL
  KVM: x86: Introduce EM_ASM_2W
  ...
2025-10-11 11:19:16 -07:00
Linus Torvalds d7ec0cf1cd Merge tag 'x86_bugs_for_v6.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 mitigation updates from Borislav Petkov:

 - Add VMSCAPE to the attack vector controls infrastructure

 - A bunch of the usual cleanups and fixlets, some of them resulting
   from fuzzing the different mitigation options

* tag 'x86_bugs_for_v6.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/bugs: Report correct retbleed mitigation status
  x86/bugs: Fix reporting of LFENCE retpoline
  x86/bugs: Fix spectre_v2 forcing
  x86/bugs: Remove uses of cpu_mitigations_off()
  x86/bugs: Simplify SSB cmdline parsing
  x86/bugs: Use early_param() for spectre_v2
  x86/bugs: Use early_param() for spectre_v2_user
  x86/bugs: Add attack vector controls for VMSCAPE
  x86/its: Move ITS indirect branch thunks to .text..__x86.indirect_thunk
2025-09-30 12:46:57 -07:00
Josh PoimboeufandBorislav Petkov (AMD) 41bab90bbf x86/its: Move ITS indirect branch thunks to .text..__x86.indirect_thunk
The ITS mitigation includes both indirect branch thunks and return
thunks.  Both are currently placed in .text..__x86.return_thunk, which is
appropriate for the latter but not the former.

For consistency with other mitigations, move the indirect branch thunks to
.text..__x86.indirect_thunk.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
2025-09-12 12:14:54 +02:00
Peter Zijlstra 85a2d4a890 x86,ibt: Use UDB instead of 0xEA
A while ago [0] FineIBT started using the 0xEA instruction to raise #UD.
All existing parts will generate #UD in 64bit mode on that instruction.

However; Intel/AMD have not blessed using this instruction, it is on
their 'reserved' opcode list for future use.

Peter Anvin worked the committees and got use of 0xD6 blessed, it
shall be called UDB (per the next SDM or so), and it being a single
byte instruction is easy to slip into a single byte immediate -- as
is done by this very patch.

Reworking the FineIBT code to use UDB wasn't entirely trivial. Notably
the FineIBT-BHI1 case ran out of bytes. In order to condense the
encoding some it was required to move the hash register from R10D to
EAX (thanks hpa!).

Per the x86_64 ABI, RAX is used to pass the number of vector registers
for vararg function calls -- something that should not happen in the
kernel. More so, the kernel is built with -mskip-rax-setup, which
should leave RAX completely unused, allowing its re-use.

 [ For BPF; while the bpf2bpf tail-call uses RAX in its calling
   convention, that does not use CFI and is unaffected. Only the
   'regular' C->BPF transition is covered by CFI. ]

The ENDBR poison value is changed from 'OSP NOP3' to 'NOPL -42(%RAX)',
this is basically NOP4 but with UDB as its immediate. As such it is
still a non-standard NOP value unique to prior ENDBR sites, but now
also provides UDB.

Per Agner Fog's optimization guide, Jcc is assumed not-taken. That is,
the expected path should be the fallthrough case for improved
throughput.

Since the preamble now relies on the ENDBR poison to provide UDB, the
code is changed to write the poison right along with the initial
preamble -- this is possible because the ITS mitigation already
disabled IBT over rewriting the CFI scheme.

The scheme in detail:

Preamble:

  FineIBT			FineIBT-BHI1			FineIBT-BHI

  __cfi_\func:			__cfi_\func:			__cfi_\func:
    endbr			  endbr				  endbr
    subl       $0x12345678, %eax  subl      $0x12345678, %eax	  subl       $0x12345678, %eax
    jne.d32,np \func+3		  cmovne    %rax, %rdi		  cs cs call __bhi_args_N
                                  jne.d8,np \func+3
  \func:			\func:				\func:
    nopl       -42(%rax)	  nopl      -42(%rax)		  nopl       -42(%rax)

Notably there are 7 bytes available after the SUBL; this enables the
BHI1 case to fit without the nasty overlapping case it had previously.
The !BHI case uses Jcc.d32,np to consume all 7 bytes without the need
for an additional NOP, while the BHI case uses CS padding to align the
CALL with the end of the preamble such that it returns to \func+0.

Caller:

  FineIBT				Paranoid-FineIBT

  fineibt_caller:			fineibt_caller:
    mov     $0x12345678, %eax		  mov    $0x12345678, %eax
    lea     -10(%r11), %r11		  cmp    -0x11(%r11), %eax
    nop5				  cs lea -0x10(%r11), %r11
  retpoline:				retpoline:
    cs call __x86_indirect_thunk_r11	  jne    fineibt_caller+0xd
					  call   *%r11
					  nop

Notably this is before apply_retpolines() which will fix up the
retpoline call -- since all parts with IBT also have eIBRS (lets
ignore ITS). Typically the retpoline site is rewritten (when still
intact) into:

    call *%r11
    nop3

[0] 06926c6cdb ("x86/ibt: Optimize the FineIBT instruction sequence")

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250901191307.GI4067720@noisy.programming.kicks-ass.net
2025-09-04 21:59:09 +02:00
Masami Hiramatsu (Google)andBorislav Petkov (AMD) 26178b713f x86/insn: Add XOP prefix instructions decoder support
Support decoding AMD's XOP prefix encoded instructions.

These instructions are introduced for Bulldozer micro architecture, and not
supported on Intel's processors. But when compiling kernel with
CONFIG_X86_NATIVE_CPU on some AMD processor (e.g. -march=bdver2), these
instructions can be used.

Closes: https://lore.kernel.org/all/871pq06728.fsf@wylie.me.uk/
Reported-by: Alan J. Wylie <alan@wylie.me.uk>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Alan J. Wylie <alan@wylie.me.uk>
Link: https://lore.kernel.org/175386161199.564247.597496379413236944.stgit@devnote2
2025-08-18 17:15:02 +02:00
Linus Torvalds bb78c145f7 Merge tag 'x86_core_for_v6.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cpu updates from Borislav Petkov:

 - Add helpers for WB{NO,}INVD with the purpose of using them in KVM and
   thus diminish the number of invalidations needed. With preceding
   cleanups, as always

* tag 'x86_core_for_v6.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/lib: Add WBINVD and WBNOINVD helpers to target multiple CPUs
  x86/lib: Add WBNOINVD helper functions
  x86/lib: Drop the unused return value from wbinvd_on_all_cpus()
  drm/gpu: Remove dead checks on wbinvd_on_all_cpus()'s return value
2025-07-29 16:55:29 -07:00
Linus Torvalds 13150742b0 Merge tag 'libcrypto-updates-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux
Pull crypto library updates from Eric Biggers:
 "This is the main crypto library pull request for 6.17. The main focus
  this cycle is on reorganizing the SHA-1 and SHA-2 code, providing
  high-quality library APIs for SHA-1 and SHA-2 including HMAC support,
  and establishing conventions for lib/crypto/ going forward:

   - Migrate the SHA-1 and SHA-512 code (and also SHA-384 which shares
     most of the SHA-512 code) into lib/crypto/. This includes both the
     generic and architecture-optimized code. Greatly simplify how the
     architecture-optimized code is integrated. Add an easy-to-use
     library API for each SHA variant, including HMAC support. Finally,
     reimplement the crypto_shash support on top of the library API.

   - Apply the same reorganization to the SHA-256 code (and also SHA-224
     which shares most of the SHA-256 code). This is a somewhat smaller
     change, due to my earlier work on SHA-256. But this brings in all
     the same additional improvements that I made for SHA-1 and SHA-512.

  There are also some smaller changes:

   - Move the architecture-optimized ChaCha, Poly1305, and BLAKE2s code
     from arch/$(SRCARCH)/lib/crypto/ to lib/crypto/$(SRCARCH)/. For
     these algorithms it's just a move, not a full reorganization yet.

   - Fix the MIPS chacha-core.S to build with the clang assembler.

   - Fix the Poly1305 functions to work in all contexts.

   - Fix a performance regression in the x86_64 Poly1305 code.

   - Clean up the x86_64 SHA-NI optimized SHA-1 assembly code.

  Note that since the new organization of the SHA code is much simpler,
  the diffstat of this pull request is negative, despite the addition of
  new fully-documented library APIs for multiple SHA and HMAC-SHA
  variants.

  These APIs will allow further simplifications across the kernel as
  users start using them instead of the old-school crypto API. (I've
  already written a lot of such conversion patches, removing over 1000
  more lines of code. But most of those will target 6.18 or later)"

* tag 'libcrypto-updates-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux: (67 commits)
  lib/crypto: arm64/sha512-ce: Drop compatibility macros for older binutils
  lib/crypto: x86/sha1-ni: Convert to use rounds macros
  lib/crypto: x86/sha1-ni: Minor optimizations and cleanup
  crypto: sha1 - Remove sha1_base.h
  lib/crypto: x86/sha1: Migrate optimized code into library
  lib/crypto: sparc/sha1: Migrate optimized code into library
  lib/crypto: s390/sha1: Migrate optimized code into library
  lib/crypto: powerpc/sha1: Migrate optimized code into library
  lib/crypto: mips/sha1: Migrate optimized code into library
  lib/crypto: arm64/sha1: Migrate optimized code into library
  lib/crypto: arm/sha1: Migrate optimized code into library
  crypto: sha1 - Use same state format as legacy drivers
  crypto: sha1 - Wrap library and add HMAC support
  lib/crypto: sha1: Add HMAC support
  lib/crypto: sha1: Add SHA-1 library functions
  lib/crypto: sha1: Rename sha1_init() to sha1_init_raw()
  crypto: x86/sha1 - Rename conflicting symbol
  lib/crypto: sha2: Add hmac_sha*_init_usingrawkey()
  lib/crypto: arm/poly1305: Remove unneeded empty weak function
  lib/crypto: x86/poly1305: Fix performance regression on short messages
  ...
2025-07-28 17:58:52 -07:00
Zheyun ShenandBorislav Petkov (AMD) 4fdc3431e0 x86/lib: Add WBINVD and WBNOINVD helpers to target multiple CPUs
Extract KVM's open-coded calls to do writeback caches on multiple CPUs to
common library helpers for both WBINVD and WBNOINVD (KVM will use both).
Put the onus on the caller to check for a non-empty mask to simplify the
SMP=n implementation, e.g. so that it doesn't need to check that the one
and only CPU in the system is present in the mask.

  [sean: move to lib, add SMP=n helpers, clarify usage]

Signed-off-by: Zheyun Shen <szy0127@sjtu.edu.cn>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Acked-by: Kai Huang <kai.huang@intel.com>
Link: https://lore.kernel.org/r/20250128015345.7929-2-szy0127@sjtu.edu.cn
Link: https://lore.kernel.org/20250522233733.3176144-5-seanjc@google.com
2025-07-10 13:30:17 +02:00