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| author | Josh Poimboeuf <jpoimboe@redhat.com> | 2020-07-17 17:04:26 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-08-05 10:59:51 +0300 |
| commit | 5f4e6b874b57a510ad38bd06b7f7ba1d209f57ad (patch) | |
| tree | b17af960ef9f957bd72ab7a6e700933cee602e95 | |
| parent | 32344d2993b0228e238dff163d7447dcf250f147 (diff) | |
| download | linux-5f4e6b874b57a510ad38bd06b7f7ba1d209f57ad.tar.xz | |
x86/stacktrace: Fix reliable check for empty user task stacks
[ Upstream commit 039a7a30ec102ec866d382a66f87f6f7654f8140 ]
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 <bobo.shaobowang@huawei.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Link: https://lkml.kernel.org/r/f136a4e5f019219cbc4f4da33b30c2f44fa65b84.1594994374.git.jpoimboe@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | arch/x86/kernel/stacktrace.c | 5 |
1 files changed, 0 insertions, 5 deletions
diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c index 2d6898c2cb64..6d83b4b857e6 100644 --- a/arch/x86/kernel/stacktrace.c +++ b/arch/x86/kernel/stacktrace.c @@ -58,7 +58,6 @@ int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry, * or a page fault), which can make frame pointers * unreliable. */ - if (IS_ENABLED(CONFIG_FRAME_POINTER)) return -EINVAL; } @@ -81,10 +80,6 @@ int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry, if (unwind_error(&state)) return -EINVAL; - /* Success path for non-user tasks, i.e. kthreads and idle tasks */ - if (!(task->flags & (PF_KTHREAD | PF_IDLE))) - return -EINVAL; - return 0; } |