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| author | Josh Poimboeuf <jpoimboe@redhat.com> | 2017-02-14 02:42:28 +0100 |
|---|---|---|
| committer | Jiri Kosina <jkosina@suse.cz> | 2017-03-08 09:18:02 +0100 |
| commit | af085d9084b48530153f51e6cad19fd0b1a13ed7 (patch) | |
| tree | 9b8c658ddddfe29d76c5641e346e2d2224f75363 /arch/Kconfig | |
| parent | Linux 4.11-rc1 (diff) | |
| download | linux-af085d9084b48530153f51e6cad19fd0b1a13ed7.tar.xz linux-af085d9084b48530153f51e6cad19fd0b1a13ed7.zip | |
stacktrace/x86: add function for detecting reliable stack traces
For live patching and possibly other use cases, a stack trace is only
useful if it can be assured that it's completely reliable. Add a new
save_stack_trace_tsk_reliable() function to achieve that.
Note that if the target task isn't the current task, and the target task
is allowed to run, then it could be writing the stack while the unwinder
is reading it, resulting in possible corruption. So the caller of
save_stack_trace_tsk_reliable() must ensure that the task is either
'current' or inactive.
save_stack_trace_tsk_reliable() relies on the x86 unwinder's detection
of pt_regs on the stack. If the pt_regs are not user-mode registers
from a syscall, then they indicate an in-kernel interrupt or exception
(e.g. preemption or a page fault), in which case the stack is considered
unreliable due to the nature of frame pointers.
It also relies on the x86 unwinder's detection of other issues, such as:
- corrupted stack data
- stack grows the wrong way
- stack walk doesn't reach the bottom
- user didn't provide a large enough entries array
Such issues are reported by checking unwind_error() and !unwind_done().
Also add CONFIG_HAVE_RELIABLE_STACKTRACE so arch-independent code can
determine at build time whether the function is implemented.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Ingo Molnar <mingo@kernel.org> # for the x86 changes
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'arch/Kconfig')
| -rw-r--r-- | arch/Kconfig | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/Kconfig b/arch/Kconfig index cd211a14a88f..6ad00ad73459 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -713,6 +713,12 @@ config HAVE_STACK_VALIDATION Architecture supports the 'objtool check' host tool command, which performs compile-time stack metadata validation. +config HAVE_RELIABLE_STACKTRACE + bool + help + Architecture has a save_stack_trace_tsk_reliable() function which + only returns a stack trace if it can guarantee the trace is reliable. + config HAVE_ARCH_HASH bool default n |