Randy reported objtool triggered on his (GCC-7.4) build:

  lib/strncpy_from_user.o: warning: objtool: strncpy_from_user()+0x315: call to __ubsan_handle_add_overflow() with UACCESS enabled
  lib/strnlen_user.o: warning: objtool: strnlen_user()+0x337: call to __ubsan_handle_sub_overflow() with UACCESS enabled

This is due to UBSAN generating signed-overflow-UB warnings where it
should not. Prior to GCC-8 UBSAN ignored -fwrapv (which the kernel
uses through -fno-strict-overflow).

Make the functions use 'unsigned long' throughout.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: luto@kernel.org
Link: http://lkml.kernel.org/r/20190424072208.754094071@infradead.orgSigned-off-by: Ingo Molnar <mingo@kernel.org>

The __put_user() macro evaluates it's @ptr argument inside the
__uaccess_begin() / __uaccess_end() region. While this would normally
not be expected to be an issue, an UBSAN bug (it ignored -fwrapv,
fixed in GCC 8+) would transform the @ptr evaluation for:

  drivers/gpu/drm/i915/i915_gem_execbuffer.c: if (unlikely(__put_user(offset, &urelocs[r-stack].presumed_offset))) {

into a signed-overflow-UB check and trigger the objtool AC validation.

Finish this commit:

  2a418cf3 ("x86/uaccess: Don't leak the AC flag into __put_user() value evaluation")

and explicitly evaluate all 3 arguments early.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: luto@kernel.org
Fixes: 2a418cf3 ("x86/uaccess: Don't leak the AC flag into __put_user() value evaluation")
Link: http://lkml.kernel.org/r/20190424072208.695962771@infradead.orgSigned-off-by: Ingo Molnar <mingo@kernel.org>

Now that we have objtool validating AC=1 state for all x86_64 code,
we can once again guarantee clean flags on schedule.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Having DF escape is BAD(tm).

Linus; you suggested this one, but since DF really is only used from
ASM and the failure case is fairly obvious, do we really need this?

OTOH the patch is fairly small and simple, so let's just do this
to demonstrate objtool's superior awesomeness.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

It is important that UACCESS regions are as small as possible;
furthermore the UACCESS state is not scheduled, so doing anything that
might directly call into the scheduler will cause random code to be
ran with UACCESS enabled.

Teach objtool too track UACCESS state and warn about any CALL made
while UACCESS is enabled. This very much includes the __fentry__()
and __preempt_schedule() calls.

Note that exceptions _do_ save/restore the UACCESS state, and therefore
they can drive preemption. This also means that all exception handlers
must have an otherwise redundant UACCESS disable instruction;
therefore ignore this warning for !STT_FUNC code (exception handlers
are not normal functions).
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

It turned out that we failed to detect some sibling calls;
specifically those without relocation records; like:

  $ ./objdump-func.sh defconfig-build/mm/kasan/generic.o __asan_loadN
  0000 0000000000000840 <__asan_loadN>:
  0000  840:      48 8b 0c 24             mov    (%rsp),%rcx
  0004  844:      31 d2                   xor    %edx,%edx
  0006  846:      e9 45 fe ff ff          jmpq   690 <check_memory_region>

So extend the cross-function jump to also consider those that are not
between known (or newly detected) parent/child functions, as
sibling-cals when they jump to the start of the function.

The second part of that condition is to deal with random jumps to the
middle of other function, as can be found in
arch/x86/lib/copy_user_64.S for example.

This then (with later patches applied) makes the above recognise the
sibling call:

  mm/kasan/generic.o: warning: objtool: __asan_loadN()+0x6: call to check_memory_region() with UACCESS enabled

Also make sure to set insn->call_dest for sibling calls so we can know
who we're calling. This is useful information when printing validation
warnings later.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Really skip the original instruction flow, instead of letting it
continue with NOPs.

Since the alternative code flow already continues after the original
instructions, only the alt-original is skipped.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

For when you want to know the path that reached your fail state:

  $ ./objtool check --no-fp --backtrace arch/x86/lib/usercopy_64.o
  arch/x86/lib/usercopy_64.o: warning: objtool: .altinstr_replacement+0x3: UACCESS disable without MEMOPs: __clear_user()
  arch/x86/lib/usercopy_64.o: warning: objtool:   __clear_user()+0x3a: (alt)
  arch/x86/lib/usercopy_64.o: warning: objtool:   __clear_user()+0x2e: (branch)
  arch/x86/lib/usercopy_64.o: warning: objtool:   __clear_user()+0x18: (branch)
  arch/x86/lib/usercopy_64.o: warning: objtool:   .altinstr_replacement+0xffffffffffffffff: (branch)
  arch/x86/lib/usercopy_64.o: warning: objtool:   __clear_user()+0x5: (alt)
  arch/x86/lib/usercopy_64.o: warning: objtool:   __clear_user()+0x0: <=== (func)

  0000000000000000 <__clear_user>:
    0:   e8 00 00 00 00          callq  5 <__clear_user+0x5>
                 1: R_X86_64_PLT32       __fentry__-0x4
    5:   90                      nop
    6:   90                      nop
    7:   90                      nop
    8:   48 89 f0                mov    %rsi,%rax
    b:   48 c1 ee 03             shr    $0x3,%rsi
    f:   83 e0 07                and    $0x7,%eax
   12:   48 89 f1                mov    %rsi,%rcx
   15:   48 85 c9                test   %rcx,%rcx
   18:   74 0f                   je     29 <__clear_user+0x29>
   1a:   48 c7 07 00 00 00 00    movq   $0x0,(%rdi)
   21:   48 83 c7 08             add    $0x8,%rdi
   25:   ff c9                   dec    %ecx
   27:   75 f1                   jne    1a <__clear_user+0x1a>
   29:   48 89 c1                mov    %rax,%rcx
   2c:   85 c9                   test   %ecx,%ecx
   2e:   74 0a                   je     3a <__clear_user+0x3a>
   30:   c6 07 00                movb   $0x0,(%rdi)
   33:   48 ff c7                inc    %rdi
   36:   ff c9                   dec    %ecx
   38:   75 f6                   jne    30 <__clear_user+0x30>
   3a:   90                      nop
   3b:   90                      nop
   3c:   90                      nop
   3d:   48 89 c8                mov    %rcx,%rax
   40:   c3                      retq
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

The whole add_ignores() thing was wildly weird; rewrite it according
to 'modern' ways.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Function aliases result in different symbols for the same set of
instructions; track a canonical symbol so there is a unique point of
access.

This again prepares the way for function attributes. And in particular
the need for aliases comes from how KASAN uses them.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

In preparation of function attributes, we need each instruction to
have a valid link back to its function.

Therefore make sure we set the function association for alternative
instruction sequences; they are, after all, still part of the function.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

New tooling noticed this mishap:

  kernel/kcov.o: warning: objtool: write_comp_data()+0x138: call to __stack_chk_fail() with UACCESS enabled
  kernel/kcov.o: warning: objtool: __sanitizer_cov_trace_pc()+0xd9: call to __stack_chk_fail() with UACCESS enabled

All the other instrumentation (KASAN,UBSAN) also have stack protector
disabled.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

For CONFIG_TRACE_BRANCH_PROFILING=y the likely/unlikely things get
overloaded and generate callouts to this code, and thus also when
AC=1.

Make it safe.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

UBSAN can insert extra code in random locations; including AC=1
sections. Typically this code is not safe and needs wrapping.

So far, only __ubsan_handle_type_mismatch* have been observed in AC=1
sections and therefore only those are annotated.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

KASAN inserts extra code for every LOAD/STORE emitted by te compiler.
Much of this code is simple and safe to run with AC=1, however the
kasan_report() function, called on error, is most certainly not safe
to call with AC=1.

Therefore wrap kasan_report() in user_access_{save,restore}; which for
x86 SMAP, saves/restores EFLAGS and clears AC before calling the real
function.

Also ensure all the functions are without __fentry__ hook. The
function tracer is also not safe.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Linus noticed all users of __ASM_STAC/__ASM_CLAC are with
__stringify(). Just make them a string.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Introduce common helpers for when we need to safely suspend a
uaccess section; for instance to generate a {KA,UB}SAN report.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Occasionally GCC is less agressive with inlining and the following is
observed:

  arch/x86/kernel/signal.o: warning: objtool: restore_sigcontext()+0x3cc: call to force_valid_ss.isra.5() with UACCESS enabled
  arch/x86/kernel/signal.o: warning: objtool: do_signal()+0x384: call to frame_uc_flags.isra.0() with UACCESS enabled

Cure this by moving this code out of the AC=1 region, since it really
isn't needed for the user access.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

If GCC out-of-lines it, the STAC and CLAC are in different fuctions
and objtool gets upset.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

drivers/xen/privcmd.o: warning: objtool: privcmd_ioctl()+0x1414: call to hypercall_page() with UACCESS enabled

Some Xen hypercalls allow parameter buffers in user land, so they need
to set AC=1. Avoid the warning for those cases.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: Borislav Petkov <bp@alien8.de>
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: andrew.cooper3@citrix.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

To facillitate other usage of ignoring alternatives; rename
ANNOTATE_NOSPEC_IGNORE to ANNOTATE_IGNORE_ALTERNATIVE.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

New tooling got confused about this:

  arch/x86/lib/memcpy_64.o: warning: objtool: .fixup+0x7: return with UACCESS enabled

While the code isn't wrong, it is tedious (if at all possible) to
figure out what function a particular chunk of .fixup belongs to.

This then confuses the objtool uaccess validation. Instead of
returning directly from the .fixup, jump back into the right function.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

By writing the function in asm we avoid cross object code flow and
objtool no longer gets confused about a 'stray' CLAC.

Also; the asm version is actually _simpler_.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

New tooling noticed this:

 drivers/gpu/drm/i915/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0x3c: redundant UACCESS disable
 drivers/gpu/drm/i915/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0x66: redundant UACCESS disable

You don't need user_access_end() if user_access_begin() fails.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Objtool spotted that we call native_load_gs_index() with AC set.
Re-arrange the code to avoid that.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

With CONFIG_PROFILE_ALL_BRANCHES=y, the "if" macro converts the
conditional to an array index.  This can cause GCC to create horrible
code.  When there are nested ifs, the generated code uses register
values to encode branching decisions.

Make it easier for GCC to optimize by keeping the conditional as a
conditional rather than converting it to an integer.  This shrinks the
generated code quite a bit, and also makes the code sane enough for
objtool to understand.
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: brgerst@gmail.com
Cc: catalin.marinas@arm.com
Cc: dvlasenk@redhat.com
Cc: dvyukov@google.com
Cc: hpa@zytor.com
Cc: james.morse@arm.com
Cc: julien.thierry@arm.com
Cc: luto@amacapital.net
Cc: luto@kernel.org
Cc: rostedt@goodmis.org
Cc: valentin.schneider@arm.com
Cc: will.deacon@arm.com
Link: https://lkml.kernel.org/r/20190307174802.46fmpysxyo35hh43@trebleSigned-off-by: Ingo Molnar <mingo@kernel.org>

Effectively reverts commit:

  2c7577a7 ("sched/x86_64: Don't save flags on context switch")

Specifically because SMAP uses FLAGS.AC which invalidates the claim
that the kernel has clean flags.

In particular; while preemption from interrupt return is fine (the
IRET frame on the exception stack contains FLAGS) it breaks any code
that does synchonous scheduling, including preempt_enable().

This has become a significant issue ever since commit:

  5b24a7a2 ("Add 'unsafe' user access functions for batched accesses")

provided for means of having 'normal' C code between STAC / CLAC,
exposing the FLAGS.AC state. So far this hasn't led to trouble,
however fix it before it comes apart.
Reported-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@kernel.org
Fixes: 5b24a7a2 ("Add 'unsafe' user access functions for batched accesses")
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Pull aio race fixes and cleanups from Al Viro.

The aio code had more issues with error handling and races with the aio
completing at just the right (wrong) time along with freeing the file
descriptor when another thread closes the file.

Just a couple of these commits are the actual fixes: the others are
cleanups to either make the fixes simpler, or to make the code legible
and understandable enough that we hope there's no more fundamental races
hiding.

* 'work.aio' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  aio: move sanity checks and request allocation to io_submit_one()
  deal with get_reqs_available() in aio_get_req() itself
  aio: move dropping ->ki_eventfd into iocb_destroy()
  make aio_read()/aio_write() return int
  Fix aio_poll() races
  aio: store event at final iocb_put()
  aio: keep io_event in aio_kiocb
  aio: fold lookup_kiocb() into its sole caller
  pin iocb through aio.

Pull symlink fixes from Al Viro:
 "The ceph fix is already in mainline, Daniel's bpf fix is in bpf tree
  (1da6c4d9 "bpf: fix use after free in bpf_evict_inode"), the rest
  is in here"

* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  debugfs: fix use-after-free on symlink traversal
  ubifs: fix use-after-free on symlink traversal
  jffs2: fix use-after-free on symlink traversal

symlink body shouldn't be freed without an RCU delay.  Switch debugfs to
->destroy_inode() and use of call_rcu(); free both the inode and symlink
body in the callback.  Similar to solution for bpf, only here it's even
more obvious that ->evict_inode() can be dropped.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

free the symlink body after the same RCU delay we have for freeing the
struct inode itself, so that traversal during RCU pathwalk wouldn't step
into freed memory.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

free the symlink body after the same RCU delay we have for freeing the
struct inode itself, so that traversal during RCU pathwalk wouldn't step
into freed memory.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Pull KVM fixes from Paolo Bonzini:
 "A collection of x86 and ARM bugfixes, and some improvements to
  documentation.

  On top of this, a cleanup of kvm_para.h headers, which were exported
  by some architectures even though they not support KVM at all. This is
  responsible for all the Kbuild changes in the diffstat"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (28 commits)
  Documentation: kvm: clarify KVM_SET_USER_MEMORY_REGION
  KVM: doc: Document the life cycle of a VM and its resources
  KVM: selftests: complete IO before migrating guest state
  KVM: selftests: disable stack protector for all KVM tests
  KVM: selftests: explicitly disable PIE for tests
  KVM: selftests: assert on exit reason in CR4/cpuid sync test
  KVM: x86: update %rip after emulating IO
  x86/kvm/hyper-v: avoid spurious pending stimer on vCPU init
  kvm/x86: Move MSR_IA32_ARCH_CAPABILITIES to array emulated_msrs
  KVM: x86: Emulate MSR_IA32_ARCH_CAPABILITIES on AMD hosts
  kvm: don't redefine flags as something else
  kvm: mmu: Used range based flushing in slot_handle_level_range
  KVM: export <linux/kvm_para.h> and <asm/kvm_para.h> iif KVM is supported
  KVM: x86: remove check on nr_mmu_pages in kvm_arch_commit_memory_region()
  kvm: nVMX: Add a vmentry check for HOST_SYSENTER_ESP and HOST_SYSENTER_EIP fields
  KVM: SVM: Workaround errata#1096 (insn_len maybe zero on SMAP violation)
  KVM: Reject device ioctls from processes other than the VM's creator
  KVM: doc: Fix incorrect word ordering regarding supported use of APIs
  KVM: x86: fix handling of role.cr4_pae and rename it to 'gpte_size'
  KVM: nVMX: Do not inherit quadrant and invalid for the root shadow EPT
  ...

Pull x86 fixes from Thomas Gleixner:
 "A pile of x86 updates:

   - Prevent exceeding he valid physical address space in the /dev/mem
     limit checks.

   - Move all header content inside the header guard to prevent compile
     failures.

   - Fix the bogus __percpu annotation in this_cpu_has() which makes
     sparse very noisy.

   - Disable switch jump tables completely when retpolines are enabled.

   - Prevent leaking the trampoline address"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/realmode: Make set_real_mode_mem() static inline
  x86/cpufeature: Fix __percpu annotation in this_cpu_has()
  x86/mm: Don't exceed the valid physical address space
  x86/retpolines: Disable switch jump tables when retpolines are enabled
  x86/realmode: Don't leak the trampoline kernel address
  x86/boot: Fix incorrect ifdeffery scope
  x86/resctrl: Remove unused variable

Pull perf tooling fixes from Thomas Gleixner:
 "Core libraries:
   - Fix max perf_event_attr.precise_ip detection.
   - Fix parser error for uncore event alias
   - Fixup ordering of kernel maps after obtaining the main kernel map
     address.

  Intel PT:
   - Fix TSC slip where A TSC packet can slip past MTC packets so that
     the timestamp appears to go backwards.
   - Fixes for exported-sql-viewer GUI conversion to python3.

  ARM coresight:
   - Fix the build by adding a missing case value for enumeration value
     introduced in newer library, that now is the required one.

  tool headers:
   - Syncronize kernel headers with the kernel, getting new io_uring and
     pidfd_send_signal syscalls so that 'perf trace' can handle them"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf pmu: Fix parser error for uncore event alias
  perf scripts python: exported-sql-viewer.py: Fix python3 support
  perf scripts python: exported-sql-viewer.py: Fix never-ending loop
  perf machine: Update kernel map address and re-order properly
  tools headers uapi: Sync powerpc's asm/kvm.h copy with the kernel sources
  tools headers: Update x86's syscall_64.tbl and uapi/asm-generic/unistd
  tools headers uapi: Update drm/i915_drm.h
  tools arch x86: Sync asm/cpufeatures.h with the kernel sources
  tools headers uapi: Sync linux/fcntl.h to get the F_SEAL_FUTURE_WRITE addition
  tools headers uapi: Sync asm-generic/mman-common.h and linux/mman.h
  perf evsel: Fix max perf_event_attr.precise_ip detection
  perf intel-pt: Fix TSC slip
  perf cs-etm: Add missing case value

Pull CPU hotplug fixes from Thomas Gleixner:
 "Two SMT/hotplug related fixes:

   - Prevent crash when HOTPLUG_CPU is disabled and the CPU bringup
     aborts. This is triggered with the 'nosmt' command line option, but
     can happen by any abort condition. As the real unplug code is not
     compiled in, prevent the fail by keeping the CPU in zombie state.

   - Enforce HOTPLUG_CPU for SMP on x86 to avoid the above situation
     completely. With 'nosmt' being a popular option it's required to
     unplug the half brought up sibling CPUs (due to the MCE wreckage)
     completely"

* 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/smp: Enforce CONFIG_HOTPLUG_CPU when SMP=y
  cpu/hotplug: Prevent crash when CPU bringup fails on CONFIG_HOTPLUG_CPU=n

Pull locking fixlet from Thomas Gleixner:
 "Trivial update to the maintainers file"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  MAINTAINERS: Remove deleted file from futex file pattern

Pull core fixes from Thomas Gleixner:
 "A small set of core updates:

   - Make the watchdog respect the selected CPU mask again. That was
     broken by the rework of the watchdog thread management and caused
     inconsistent state and NMI watchdog being unstoppable.

   - Ensure that the objtool build can find the libelf location.

   - Remove dead kcore stub code"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  watchdog: Respect watchdog cpumask on CPU hotplug
  objtool: Query pkg-config for libelf location
  proc/kcore: Remove unused kclist_add_remap()

Pull powerpc fixes from Michael Ellerman:
 "Three non-regression fixes.

   - Our optimised memcmp could read past the end of one of the buffers
     and potentially trigger a page fault leading to an oops.

   - Some of our code to read energy management data on PowerVM had an
     endian bug leading to bogus results.

   - When reporting a machine check exception we incorrectly reported
     TLB multihits as D-Cache multhits due to a missing entry in the
     array of causes.

  Thanks to: Chandan Rajendra, Gautham R. Shenoy, Mahesh Salgaonkar,
  Segher Boessenkool, Vaidyanathan Srinivasan"

* tag 'powerpc-5.1-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/pseries/mce: Fix misleading print for TLB mutlihit
  powerpc/pseries/energy: Use OF accessor functions to read ibm,drc-indexes
  powerpc/64: Fix memcmp reading past the end of src/dest