linux-stable.git/arch/x86/kernel/stacktrace.c, branch linux-rolling-lts

x86: remove __range_not_ok()

2022-02-25T08:36:05+00:00

The __range_not_ok() helper is an x86 (and sparc64) specific interface
that does roughly the same thing as __access_ok(), but with different
calling conventions.

Change this to use the normal interface in order for consistency as we
clean up all access_ok() implementations.

This changes the limit from TASK_SIZE to TASK_SIZE_MAX, which Al points
out is the right thing do do here anyway.

The callers have to use __access_ok() instead of the normal access_ok()
though, because on x86 that contains a WARN_ON_IN_IRQ() check that cannot
be used inside of NMI context while tracing.

The check in copy_code() is not needed any more, because this one is
already done by copy_from_user_nmi().

Suggested-by: Al Viro 
Suggested-by: Christoph Hellwig 
Link: https://lore.kernel.org/lkml/YgsUKcXGR7r4nINj@zeniv-ca.linux.org.uk/
Signed-off-by: Arnd Bergmann

stacktrace: Move documentation for arch_stack_walk_reliable() to header

2021-03-10T14:52:31+00:00

Currently arch_stack_walk_reliable() is documented with an identical
comment in both x86 and S/390 implementations which is a bit redundant.
Move this to the header and convert to kerneldoc while we're at it.

Signed-off-by: Mark Brown 
Signed-off-by: Borislav Petkov 
Reviewed-by: Miroslav Benes 
Acked-by: Vasily Gorbik 
Acked-by: Randy Dunlap 
Link: https://lkml.kernel.org/r/20210309194125.652-1-broonie@kernel.org

stacktrace: Remove reliable argument from arch_stack_walk() callback

2020-09-18T13:24:16+00:00

Currently the callback passed to arch_stack_walk() has an argument called
reliable passed to it to indicate if the stack entry is reliable, a comment
says that this is used by some printk() consumers. However in the current
kernel none of the arch_stack_walk() implementations ever set this flag to
true and the only callback implementation we have is in the generic
stacktrace code which ignores the flag. It therefore appears that this
flag is redundant so we can simplify and clarify things by removing it.

Signed-off-by: Mark Brown 
Reviewed-by: Miroslav Benes 
Link: https://lore.kernel.org/r/20200914153409.25097-2-broonie@kernel.org
Signed-off-by: Will Deacon

x86/stacktrace: Fix reliable check for empty user task stacks

2020-07-22T21:47:47+00:00

If a user task's stack is empty, or if it only has user regs, ORC
reports it as a reliable empty stack.  But arch_stack_walk_reliable()
incorrectly treats it as unreliable.

That happens because the only success path for user tasks is inside the
loop, which only iterates on non-empty stacks.  Generally, a user task
must end in a user regs frame, but an empty stack is an exception to
that rule.

Thanks to commit 71c95825289f ("x86/unwind/orc: Fix error handling in
__unwind_start()"), unwind_start() now sets state->error appropriately.
So now for both ORC and FP unwinders, unwind_done() and !unwind_error()
always means the end of the stack was successfully reached.  So the
success path for kthreads is no longer needed -- it can also be used for
empty user tasks.

Reported-by: Wang ShaoBo 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Thomas Gleixner 
Tested-by: Wang ShaoBo 
Link: https://lkml.kernel.org/r/f136a4e5f019219cbc4f4da33b30c2f44fa65b84.1594994374.git.jpoimboe@redhat.com

x86 user stack frame reads: switch to explicit __get_user()

2020-02-15T22:26:26+00:00

rather than relying upon the magic in raw_copy_from_user()

Signed-off-by: Al Viro

x86/stacktrace: Prevent access_ok() warnings in arch_stack_walk_user()

2019-07-22T08:42:36+00:00

When arch_stack_walk_user() is called from atomic contexts, access_ok() can
trigger the following warning if compiled with CONFIG_DEBUG_ATOMIC_SLEEP=y.

Reproducer:

  // CONFIG_DEBUG_ATOMIC_SLEEP=y
  # cd /sys/kernel/debug/tracing
  # echo 1 > options/userstacktrace
  # echo 1 > events/irq/irq_handler_entry/enable

  WARNING: CPU: 0 PID: 2649 at arch/x86/kernel/stacktrace.c:103 arch_stack_walk_user+0x6e/0xf6
  CPU: 0 PID: 2649 Comm: bash Not tainted 5.3.0-rc1+ #99
  RIP: 0010:arch_stack_walk_user+0x6e/0xf6
  Call Trace:
   
   stack_trace_save_user+0x10a/0x16d
   trace_buffer_unlock_commit_regs+0x185/0x240
   trace_event_buffer_commit+0xec/0x330
   trace_event_raw_event_irq_handler_entry+0x159/0x1e0
   __handle_irq_event_percpu+0x22d/0x440
   handle_irq_event_percpu+0x70/0x100
   handle_irq_event+0x5a/0x8b
   handle_edge_irq+0x12f/0x3f0
   handle_irq+0x34/0x40
   do_IRQ+0xa6/0x1f0
   common_interrupt+0xf/0xf
   

Fix it by calling __range_not_ok() directly instead of access_ok() as
copy_from_user_nmi() does. This is fine here because the actual copy is
inside a pagefault disabled region.

Reported-by: Juri Lelli 
Signed-off-by: Eiichi Tsukata 
Signed-off-by: Thomas Gleixner 
Link: https://lkml.kernel.org/r/20190722083216.16192-2-devel@etsukata.com

x86/stacktrace: Prevent infinite loop in arch_stack_walk_user()

2019-07-11T06:22:03+00:00

arch_stack_walk_user() checks `if (fp == frame.next_fp)` to prevent a
infinite loop by self reference but it's not enogh for circular reference.

Once a lack of return address is found, there is no point to continue the
loop, so break out.

Fixes: 02b67518e2b1 ("tracing: add support for userspace stacktraces in tracing/iter_ctrl")
Signed-off-by: Eiichi Tsukata 
Signed-off-by: Thomas Gleixner 
Acked-by: Linus Torvalds 
Link: https://lkml.kernel.org/r/20190711023501.963-1-devel@etsukata.com

x86/stacktrace: Use common infrastructure

2019-04-29T10:37:57+00:00

Replace the stack_trace_save*() functions with the new arch_stack_walk()
interfaces.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Josh Poimboeuf 
Cc: Andy Lutomirski 
Cc: linux-arch@vger.kernel.org
Cc: Steven Rostedt 
Cc: Alexander Potapenko 
Cc: Alexey Dobriyan 
Cc: Andrew Morton 
Cc: Christoph Lameter 
Cc: Pekka Enberg 
Cc: linux-mm@kvack.org
Cc: David Rientjes 
Cc: Catalin Marinas 
Cc: Dmitry Vyukov 
Cc: Andrey Ryabinin 
Cc: kasan-dev@googlegroups.com
Cc: Mike Rapoport 
Cc: Akinobu Mita 
Cc: Christoph Hellwig 
Cc: iommu@lists.linux-foundation.org
Cc: Robin Murphy 
Cc: Marek Szyprowski 
Cc: Johannes Thumshirn 
Cc: David Sterba 
Cc: Chris Mason 
Cc: Josef Bacik 
Cc: linux-btrfs@vger.kernel.org
Cc: dm-devel@redhat.com
Cc: Mike Snitzer 
Cc: Alasdair Kergon 
Cc: Daniel Vetter 
Cc: intel-gfx@lists.freedesktop.org
Cc: Joonas Lahtinen 
Cc: Maarten Lankhorst 
Cc: dri-devel@lists.freedesktop.org
Cc: David Airlie 
Cc: Jani Nikula 
Cc: Rodrigo Vivi 
Cc: Tom Zanussi 
Cc: Miroslav Benes 
Link: https://lkml.kernel.org/r/20190425094803.816485461@linutronix.de

x86/stacktrace: Remove the pointless ULONG_MAX marker

2019-04-14T17:58:27+00:00

Terminating the last trace entry with ULONG_MAX is a completely pointless
exercise and none of the consumers can rely on it because it's
inconsistently implemented across architectures. In fact quite some of the
callers remove the entry and adjust stack_trace.nr_entries afterwards.

Signed-off-by: Thomas Gleixner 
Acked-by: Peter Zijlstra (Intel) 
Cc: Josh Poimboeuf 
Cc: Andy Lutomirski 
Cc: Steven Rostedt 
Cc: Alexander Potapenko 
Link: https://lkml.kernel.org/r/20190410103643.750954603@linutronix.de

Remove 'type' argument from access_ok() function

2019-01-04T02:57:57+00:00

Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument
of the user address range verification function since we got rid of the
old racy i386-only code to walk page tables by hand.

It existed because the original 80386 would not honor the write protect
bit when in kernel mode, so you had to do COW by hand before doing any
user access.  But we haven't supported that in a long time, and these
days the 'type' argument is a purely historical artifact.

A discussion about extending 'user_access_begin()' to do the range
checking resulted this patch, because there is no way we're going to
move the old VERIFY_xyz interface to that model.  And it's best done at
the end of the merge window when I've done most of my merges, so let's
just get this done once and for all.

This patch was mostly done with a sed-script, with manual fix-ups for
the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form.

There were a couple of notable cases:

 - csky still had the old "verify_area()" name as an alias.

 - the iter_iov code had magical hardcoded knowledge of the actual
   values of VERIFY_{READ,WRITE} (not that they mattered, since nothing
   really used it)

 - microblaze used the type argument for a debug printout

but other than those oddities this should be a total no-op patch.

I tried to fix up all architectures, did fairly extensive grepping for
access_ok() uses, and the changes are trivial, but I may have missed
something.  Any missed conversion should be trivially fixable, though.

Signed-off-by: Linus Torvalds