| Message ID | 20250127213310.2496133-7-wnliu@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | unwind, arm64: add sframe unwinder for kernel | expand |
On 28-01-2025 03:03, Weinan Liu wrote: > To support livepatch, we need to add arch_stack_walk_reliable to > support reliable stacktrace according to > https://docs.kernel.org/livepatch/reliable-stacktrace.html#requirements > > report stacktrace is not reliable if we are not able to unwind the stack > by sframe unwinder and fallback to FP based unwinder > > Signed-off-by: Weinan Liu <wnliu@google.com> > --- > arch/arm64/include/asm/stacktrace/common.h | 2 + > arch/arm64/kernel/stacktrace.c | 47 +++++++++++++++++++++- > 2 files changed, 47 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/include/asm/stacktrace/common.h b/arch/arm64/include/asm/stacktrace/common.h > index 19edae8a5b1a..26449cd402db 100644 > --- a/arch/arm64/include/asm/stacktrace/common.h > +++ b/arch/arm64/include/asm/stacktrace/common.h > @@ -26,6 +26,7 @@ struct stack_info { > * @stacks: An array of stacks which can be unwound. > * @nr_stacks: The number of stacks in @stacks. > * @cfa: The sp value at the call site of the current function. > + * @unreliable: Stacktrace is unreliable. > */ > struct unwind_state { > unsigned long fp; > @@ -36,6 +37,7 @@ struct unwind_state { > int nr_stacks; > #ifdef CONFIG_SFRAME_UNWINDER > unsigned long cfa; > + bool unreliable; > #endif > }; > > diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c > index c035adb8fe8a..eab16dc05bb5 100644 > --- a/arch/arm64/kernel/stacktrace.c > +++ b/arch/arm64/kernel/stacktrace.c > @@ -310,11 +310,16 @@ kunwind_next(struct kunwind_state *state) > case KUNWIND_SOURCE_TASK: > case KUNWIND_SOURCE_REGS_PC: > #ifdef CONFIG_SFRAME_UNWINDER > - err = unwind_next_frame_sframe(&state->common); > + if (!state->common.unreliable) > + err = unwind_next_frame_sframe(&state->common); > > /* Fallback to FP based unwinder */ > - if (err) > + if (err || state->common.unreliable) { > err = kunwind_next_frame_record(state); > + /* Mark its stacktrace result as unreliable if it is unwindable via FP */ > + if (!err) > + state->common.unreliable = true; > + } > #else > err = kunwind_next_frame_record(state); > #endif > @@ -446,6 +451,44 @@ noinline noinstr void arch_stack_walk(stack_trace_consume_fn consume_entry, > kunwind_stack_walk(arch_kunwind_consume_entry, &data, task, regs); > } > > +#ifdef CONFIG_SFRAME_UNWINDER > +struct kunwind_reliable_consume_entry_data { > + stack_trace_consume_fn consume_entry; > + void *cookie; > + bool unreliable; > +}; > + > +static __always_inline bool > +arch_kunwind_reliable_consume_entry(const struct kunwind_state *state, void *cookie) > +{ > + struct kunwind_reliable_consume_entry_data *data = cookie; > + > + if (state->common.unreliable) { > + data->unreliable = true; > + return false; > + } > + return data->consume_entry(data->cookie, state->common.pc); > +} > + > +noinline notrace int arch_stack_walk_reliable( > + stack_trace_consume_fn consume_entry, > + void *cookie, struct task_struct *task) > +{ > + struct kunwind_reliable_consume_entry_data data = { > + .consume_entry = consume_entry, > + .cookie = cookie, > + .unreliable = false, > + }; > + > + kunwind_stack_walk(arch_kunwind_reliable_consume_entry, &data, task, NULL); > + > + if (data.unreliable) > + return -EINVAL; > + > + return 0; > +} > +#endif > + > struct bpf_unwind_consume_entry_data { > bool (*consume_entry)(void *cookie, u64 ip, u64 sp, u64 fp); > void *cookie; Why not fold the previous patch and this into one? But the code looks good to me. Reviewed-by: Prasanna Kumar T S M <ptsm@linux.microsoft.com>.
diff --git a/arch/arm64/include/asm/stacktrace/common.h b/arch/arm64/include/asm/stacktrace/common.h index 19edae8a5b1a..26449cd402db 100644 --- a/arch/arm64/include/asm/stacktrace/common.h +++ b/arch/arm64/include/asm/stacktrace/common.h @@ -26,6 +26,7 @@ struct stack_info { * @stacks: An array of stacks which can be unwound. * @nr_stacks: The number of stacks in @stacks. * @cfa: The sp value at the call site of the current function. + * @unreliable: Stacktrace is unreliable. */ struct unwind_state { unsigned long fp; @@ -36,6 +37,7 @@ struct unwind_state { int nr_stacks; #ifdef CONFIG_SFRAME_UNWINDER unsigned long cfa; + bool unreliable; #endif }; diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index c035adb8fe8a..eab16dc05bb5 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -310,11 +310,16 @@ kunwind_next(struct kunwind_state *state) case KUNWIND_SOURCE_TASK: case KUNWIND_SOURCE_REGS_PC: #ifdef CONFIG_SFRAME_UNWINDER - err = unwind_next_frame_sframe(&state->common); + if (!state->common.unreliable) + err = unwind_next_frame_sframe(&state->common); /* Fallback to FP based unwinder */ - if (err) + if (err || state->common.unreliable) { err = kunwind_next_frame_record(state); + /* Mark its stacktrace result as unreliable if it is unwindable via FP */ + if (!err) + state->common.unreliable = true; + } #else err = kunwind_next_frame_record(state); #endif @@ -446,6 +451,44 @@ noinline noinstr void arch_stack_walk(stack_trace_consume_fn consume_entry, kunwind_stack_walk(arch_kunwind_consume_entry, &data, task, regs); } +#ifdef CONFIG_SFRAME_UNWINDER +struct kunwind_reliable_consume_entry_data { + stack_trace_consume_fn consume_entry; + void *cookie; + bool unreliable; +}; + +static __always_inline bool +arch_kunwind_reliable_consume_entry(const struct kunwind_state *state, void *cookie) +{ + struct kunwind_reliable_consume_entry_data *data = cookie; + + if (state->common.unreliable) { + data->unreliable = true; + return false; + } + return data->consume_entry(data->cookie, state->common.pc); +} + +noinline notrace int arch_stack_walk_reliable( + stack_trace_consume_fn consume_entry, + void *cookie, struct task_struct *task) +{ + struct kunwind_reliable_consume_entry_data data = { + .consume_entry = consume_entry, + .cookie = cookie, + .unreliable = false, + }; + + kunwind_stack_walk(arch_kunwind_reliable_consume_entry, &data, task, NULL); + + if (data.unreliable) + return -EINVAL; + + return 0; +} +#endif + struct bpf_unwind_consume_entry_data { bool (*consume_entry)(void *cookie, u64 ip, u64 sp, u64 fp); void *cookie;
To support livepatch, we need to add arch_stack_walk_reliable to support reliable stacktrace according to https://docs.kernel.org/livepatch/reliable-stacktrace.html#requirements report stacktrace is not reliable if we are not able to unwind the stack by sframe unwinder and fallback to FP based unwinder Signed-off-by: Weinan Liu <wnliu@google.com> --- arch/arm64/include/asm/stacktrace/common.h | 2 + arch/arm64/kernel/stacktrace.c | 47 +++++++++++++++++++++- 2 files changed, 47 insertions(+), 2 deletions(-)