| Message ID | 20220617210717.27126-2-madvenka@linux.microsoft.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: Reorganize the unwinder and implement stack trace reliability checks | expand |
On Fri, Jun 17, 2022 at 04:07:12PM -0500, madvenka@linux.microsoft.com wrote: > From: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com> > > unwind_init() is currently a single function that initializes all of the > unwind state. Split it into the following functions and call them > appropriately: > > - unwind_init_from_regs() - initialize from regs passed by caller. > > - unwind_init_from_caller() - initialize for the current task > from the caller of arch_stack_walk(). > > - unwind_init_from_task() - initialize from the saved state of a > task other than the current task. In this case, the other > task must not be running. > > This is done for two reasons: > > - the different ways of initializing are clear > > - specialized code can be added to each initializer in the future. > > Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> > Reviewed-by: Mark Brown <broonie@kernel.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Mark. > --- > arch/arm64/kernel/stacktrace.c | 66 ++++++++++++++++++++++++++++------ > 1 file changed, 55 insertions(+), 11 deletions(-) > > diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c > index 0467cb79f080..e44f93ff25f0 100644 > --- a/arch/arm64/kernel/stacktrace.c > +++ b/arch/arm64/kernel/stacktrace.c > @@ -50,11 +50,8 @@ struct unwind_state { > #endif > }; > > -static notrace void unwind_init(struct unwind_state *state, unsigned long fp, > - unsigned long pc) > +static void unwind_init_common(struct unwind_state *state) > { > - state->fp = fp; > - state->pc = pc; > #ifdef CONFIG_KRETPROBES > state->kr_cur = NULL; > #endif > @@ -72,7 +69,57 @@ static notrace void unwind_init(struct unwind_state *state, unsigned long fp, > state->prev_fp = 0; > state->prev_type = STACK_TYPE_UNKNOWN; > } > -NOKPROBE_SYMBOL(unwind_init); > + > +/* > + * Start an unwind from a pt_regs. > + * > + * The unwind will begin at the PC within the regs. > + * > + * The regs must be on a stack currently owned by the calling task. > + */ > +static inline void unwind_init_from_regs(struct unwind_state *state, > + struct pt_regs *regs) > +{ > + unwind_init_common(state); > + > + state->fp = regs->regs[29]; > + state->pc = regs->pc; > +} > + > +/* > + * Start an unwind from a caller. > + * > + * The unwind will begin at the caller of whichever function this is inlined > + * into. > + * > + * The function which invokes this must be noinline. > + */ > +static __always_inline void unwind_init_from_caller(struct unwind_state *state) > +{ > + unwind_init_common(state); > + > + state->fp = (unsigned long)__builtin_frame_address(1); > + state->pc = (unsigned long)__builtin_return_address(0); > +} > + > +/* > + * Start an unwind from a blocked task. > + * > + * The unwind will begin at the blocked tasks saved PC (i.e. the caller of > + * cpu_switch_to()). > + * > + * The caller should ensure the task is blocked in cpu_switch_to() for the > + * duration of the unwind, or the unwind will be bogus. It is never valid to > + * call this for the current task. > + */ > +static inline void unwind_init_from_task(struct unwind_state *state, > + struct task_struct *task) > +{ > + unwind_init_common(state); > + > + state->fp = thread_saved_fp(task); > + state->pc = thread_saved_pc(task); > +} > > /* > * Unwind from one frame record (A) to the next frame record (B). > @@ -213,14 +260,11 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry, > struct unwind_state state; > > if (regs) > - unwind_init(&state, regs->regs[29], regs->pc); > + unwind_init_from_regs(&state, regs); > else if (task == current) > - unwind_init(&state, > - (unsigned long)__builtin_frame_address(1), > - (unsigned long)__builtin_return_address(0)); > + unwind_init_from_caller(&state); > else > - unwind_init(&state, thread_saved_fp(task), > - thread_saved_pc(task)); > + unwind_init_from_task(&state, task); > > unwind(task, &state, consume_entry, cookie); > } > -- > 2.25.1 >
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index 0467cb79f080..e44f93ff25f0 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -50,11 +50,8 @@ struct unwind_state { #endif }; -static notrace void unwind_init(struct unwind_state *state, unsigned long fp, - unsigned long pc) +static void unwind_init_common(struct unwind_state *state) { - state->fp = fp; - state->pc = pc; #ifdef CONFIG_KRETPROBES state->kr_cur = NULL; #endif @@ -72,7 +69,57 @@ static notrace void unwind_init(struct unwind_state *state, unsigned long fp, state->prev_fp = 0; state->prev_type = STACK_TYPE_UNKNOWN; } -NOKPROBE_SYMBOL(unwind_init); + +/* + * Start an unwind from a pt_regs. + * + * The unwind will begin at the PC within the regs. + * + * The regs must be on a stack currently owned by the calling task. + */ +static inline void unwind_init_from_regs(struct unwind_state *state, + struct pt_regs *regs) +{ + unwind_init_common(state); + + state->fp = regs->regs[29]; + state->pc = regs->pc; +} + +/* + * Start an unwind from a caller. + * + * The unwind will begin at the caller of whichever function this is inlined + * into. + * + * The function which invokes this must be noinline. + */ +static __always_inline void unwind_init_from_caller(struct unwind_state *state) +{ + unwind_init_common(state); + + state->fp = (unsigned long)__builtin_frame_address(1); + state->pc = (unsigned long)__builtin_return_address(0); +} + +/* + * Start an unwind from a blocked task. + * + * The unwind will begin at the blocked tasks saved PC (i.e. the caller of + * cpu_switch_to()). + * + * The caller should ensure the task is blocked in cpu_switch_to() for the + * duration of the unwind, or the unwind will be bogus. It is never valid to + * call this for the current task. + */ +static inline void unwind_init_from_task(struct unwind_state *state, + struct task_struct *task) +{ + unwind_init_common(state); + + state->fp = thread_saved_fp(task); + state->pc = thread_saved_pc(task); +} /* * Unwind from one frame record (A) to the next frame record (B). @@ -213,14 +260,11 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry, struct unwind_state state; if (regs) - unwind_init(&state, regs->regs[29], regs->pc); + unwind_init_from_regs(&state, regs); else if (task == current) - unwind_init(&state, - (unsigned long)__builtin_frame_address(1), - (unsigned long)__builtin_return_address(0)); + unwind_init_from_caller(&state); else - unwind_init(&state, thread_saved_fp(task), - thread_saved_pc(task)); + unwind_init_from_task(&state, task); unwind(task, &state, consume_entry, cookie); }