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| author |   Mark Rutland <mark.rutland@arm.com> | 2021-04-29 11:20:04 +0100 |
|---|---|---|
| committer |   Catalin Marinas <catalin.marinas@arm.com> | 2021-04-30 18:30:45 +0100 |
| commit | 8533d5bfad41e74b7dd80d292fd484913cdfb374 (patch) | |
| tree | f4b0427bf323eea7321e1c71d7cf5479eebe23dc /arch/arm64/kernel/stacktrace.c | |
| parent | arm64/vdso: Discard .note.gnu.property sections in vDSO (diff) | |
| download | wireguard-linux-8533d5bfad41e74b7dd80d292fd484913cdfb374.tar.xz wireguard-linux-8533d5bfad41e74b7dd80d292fd484913cdfb374.zip | |
arm64: stacktrace: restore terminal records
We removed the terminal frame records in commit:
6106e1112cc69a36 ("arm64: remove EL0 exception frame record")
... on the assumption that as we no longer used them to find the pt_regs
at exception boundaries, they were no longer necessary.
However, Leo reports that as an unintended side-effect, this causes
traces which cross secondary_start_kernel to terminate one entry too
late, with a spurious "0" entry.
There are a few ways we could sovle this, but as we're planning to use
terminal records for RELIABLE_STACKTRACE, let's revert the logic change
for now, keeping the update comments and accounting for the changes in
commit:
3c02600144bdb0a1 ("arm64: stacktrace: Report when we reach the end of the stack")
This is effectively a partial revert of commit:
6106e1112cc69a36 ("arm64: remove EL0 exception frame record")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Fixes: 6106e1112cc6 ("arm64: remove EL0 exception frame record")
Reported-by: Leo Yan <leo.yan@linaro.org>
Tested-by: Leo Yan <leo.yan@linaro.org>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com>
Link: https://lore.kernel.org/r/20210429104813.GA33550@C02TD0UTHF1T.local
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kernel/stacktrace.c')
| -rw-r--r-- | arch/arm64/kernel/stacktrace.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index 2a1a7a281d34..c22706aa32a1 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -68,10 +68,6 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) unsigned long fp = frame->fp; struct stack_info info; - /* Terminal record; nothing to unwind */ - if (!fp) - return -ENOENT; - if (fp & 0xf) return -EINVAL; @@ -132,6 +128,12 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) frame->pc = ptrauth_strip_insn_pac(frame->pc); + /* + * This is a terminal record, so we have finished unwinding. + */ + if (!frame->fp && !frame->pc) + return -ENOENT; + return 0; } NOKPROBE_SYMBOL(unwind_frame); |