| Message ID | 20220117145608.6781-6-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 Mon, Jan 17, 2022 at 08:56:02AM -0600, madvenka@linux.microsoft.com wrote: > From: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com> > > Copy the task argument passed to arch_stack_walk() to unwind_state so that > it can be passed to unwind functions via unwind_state rather than as a > separate argument. The task is a fundamental part of the unwind state. Reviewed-by: Mark Brown <broonie@kernel.org>
On Mon, Jan 17, 2022 at 08:56:02AM -0600, madvenka@linux.microsoft.com wrote: > From: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com> > > Copy the task argument passed to arch_stack_walk() to unwind_state so that > it can be passed to unwind functions via unwind_state rather than as a > separate argument. The task is a fundamental part of the unwind state. > > Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> > --- > arch/arm64/include/asm/stacktrace.h | 3 +++ > arch/arm64/kernel/stacktrace.c | 29 ++++++++++++++++------------- > 2 files changed, 19 insertions(+), 13 deletions(-) > > diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h > index 41ec360515f6..af423f5d7ad8 100644 > --- a/arch/arm64/include/asm/stacktrace.h > +++ b/arch/arm64/include/asm/stacktrace.h > @@ -51,6 +51,8 @@ struct stack_info { > * @kr_cur: When KRETPROBES is selected, holds the kretprobe instance > * associated with the most recently encountered replacement lr > * value. > + * > + * @task: Pointer to the task structure. Can we please say: @task: The task being unwound. > */ > struct unwind_state { > unsigned long fp; > @@ -61,6 +63,7 @@ struct unwind_state { > #ifdef CONFIG_KRETPROBES > struct llist_node *kr_cur; > #endif > + struct task_struct *task; > }; > > extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk, > diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c > index b2b568e5deba..1b32e55735aa 100644 > --- a/arch/arm64/kernel/stacktrace.c > +++ b/arch/arm64/kernel/stacktrace.c > @@ -33,8 +33,10 @@ > */ > > > -static void unwind_init_common(struct unwind_state *state) > +static void unwind_init_common(struct unwind_state *state, > + struct task_struct *task) > { > + state->task = task; > #ifdef CONFIG_KRETPROBES > state->kr_cur = NULL; > #endif > @@ -57,9 +59,10 @@ static void unwind_init_common(struct unwind_state *state) > * TODO: document requirements here. > */ > static inline void unwind_init_from_regs(struct unwind_state *state, > + struct task_struct *task, Please drop the `task` parameter here ... > struct pt_regs *regs) > { > - unwind_init_common(state); > + unwind_init_common(state, task); ... and make this: unwind_init_common(state, current); ... since that way it's *impossible* to have ismatched parameters, which is one of the reasons for having separate functions in the first place. > state->fp = regs->regs[29]; > state->pc = regs->pc; > @@ -71,9 +74,10 @@ static inline void unwind_init_from_regs(struct unwind_state *state, > * Note: this is always inlined, and we expect our caller to be a noinline > * function, such that this starts from our caller's caller. > */ > -static __always_inline void unwind_init_from_current(struct unwind_state *state) > +static __always_inline void unwind_init_from_current(struct unwind_state *state, > + struct task_struct *task) > { > - unwind_init_common(state); > + unwind_init_common(state, task); Same comments as for unwind_init_from_regs(): please drop the `task` parameter and hard-code `current` in the call to unwind_init_common(). > state->fp = (unsigned long)__builtin_frame_address(1); > state->pc = (unsigned long)__builtin_return_address(0); > @@ -87,7 +91,7 @@ static __always_inline void unwind_init_from_current(struct unwind_state *state) > static inline void unwind_init_from_task(struct unwind_state *state, > struct task_struct *task) > { > - unwind_init_common(state); > + unwind_init_common(state, task); > > state->fp = thread_saved_fp(task); > state->pc = thread_saved_pc(task); > @@ -100,11 +104,11 @@ static inline void unwind_init_from_task(struct unwind_state *state, > * records (e.g. a cycle), determined based on the location and fp value of A > * and the location (but not the fp value) of B. > */ > -static int notrace unwind_next(struct task_struct *tsk, > - struct unwind_state *state) > +static int notrace unwind_next(struct unwind_state *state) > { > unsigned long fp = state->fp; > struct stack_info info; > + struct task_struct *tsk = state->task; > > /* Final frame; nothing to unwind */ > if (fp == (unsigned long)task_pt_regs(tsk)->stackframe) > @@ -176,8 +180,7 @@ static int notrace unwind_next(struct task_struct *tsk, > } > NOKPROBE_SYMBOL(unwind_next); > > -static void notrace unwind(struct task_struct *tsk, > - struct unwind_state *state, > +static void notrace unwind(struct unwind_state *state, > bool (*fn)(void *, unsigned long), void *data) > { > while (1) { > @@ -185,7 +188,7 @@ static void notrace unwind(struct task_struct *tsk, > > if (!fn(data, state->pc)) > break; > - ret = unwind_next(tsk, state); > + ret = unwind_next(state); > if (ret < 0) > break; > } > @@ -232,11 +235,11 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry, > struct unwind_state state; > > if (regs) > - unwind_init_from_regs(&state, regs); > + unwind_init_from_regs(&state, task, regs); > else if (task == current) > - unwind_init_from_current(&state); > + unwind_init_from_current(&state, task); > else > unwind_init_from_task(&state, task); As above we shouldn't need these two changes. For the regs case we might want to sanity-check that task == current. > - unwind(task, &state, consume_entry, cookie); > + unwind(&state, consume_entry, cookie); Otherwise, this looks good to me. Thanks, Mark.
It looks like I forgot to reply to this. Sorry about that. On 2/15/22 07:22, Mark Rutland wrote: > On Mon, Jan 17, 2022 at 08:56:02AM -0600, madvenka@linux.microsoft.com wrote: >> From: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com> >> >> Copy the task argument passed to arch_stack_walk() to unwind_state so that >> it can be passed to unwind functions via unwind_state rather than as a >> separate argument. The task is a fundamental part of the unwind state. >> >> Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> >> --- >> arch/arm64/include/asm/stacktrace.h | 3 +++ >> arch/arm64/kernel/stacktrace.c | 29 ++++++++++++++++------------- >> 2 files changed, 19 insertions(+), 13 deletions(-) >> >> diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h >> index 41ec360515f6..af423f5d7ad8 100644 >> --- a/arch/arm64/include/asm/stacktrace.h >> +++ b/arch/arm64/include/asm/stacktrace.h >> @@ -51,6 +51,8 @@ struct stack_info { >> * @kr_cur: When KRETPROBES is selected, holds the kretprobe instance >> * associated with the most recently encountered replacement lr >> * value. >> + * >> + * @task: Pointer to the task structure. > > Can we please say: > > @task: The task being unwound. > Will do. >> */ >> struct unwind_state { >> unsigned long fp; >> @@ -61,6 +63,7 @@ struct unwind_state { >> #ifdef CONFIG_KRETPROBES >> struct llist_node *kr_cur; >> #endif >> + struct task_struct *task; >> }; >> >> extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk, >> diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c >> index b2b568e5deba..1b32e55735aa 100644 >> --- a/arch/arm64/kernel/stacktrace.c >> +++ b/arch/arm64/kernel/stacktrace.c >> @@ -33,8 +33,10 @@ >> */ >> >> >> -static void unwind_init_common(struct unwind_state *state) >> +static void unwind_init_common(struct unwind_state *state, >> + struct task_struct *task) >> { >> + state->task = task; >> #ifdef CONFIG_KRETPROBES >> state->kr_cur = NULL; >> #endif >> @@ -57,9 +59,10 @@ static void unwind_init_common(struct unwind_state *state) >> * TODO: document requirements here. >> */ >> static inline void unwind_init_from_regs(struct unwind_state *state, >> + struct task_struct *task, > > Please drop the `task` parameter here ... OK. > >> struct pt_regs *regs) >> { >> - unwind_init_common(state); >> + unwind_init_common(state, task); > > ... and make this: > > unwind_init_common(state, current); OK. > > ... since that way it's *impossible* to have ismatched parameters, which is one > of the reasons for having separate functions in the first place. > >> state->fp = regs->regs[29]; >> state->pc = regs->pc; >> @@ -71,9 +74,10 @@ static inline void unwind_init_from_regs(struct unwind_state *state, >> * Note: this is always inlined, and we expect our caller to be a noinline >> * function, such that this starts from our caller's caller. >> */ >> -static __always_inline void unwind_init_from_current(struct unwind_state *state) >> +static __always_inline void unwind_init_from_current(struct unwind_state *state, >> + struct task_struct *task) >> { >> - unwind_init_common(state); >> + unwind_init_common(state, task); > > Same comments as for unwind_init_from_regs(): please drop the `task` parameter > and hard-code `current` in the call to unwind_init_common(). > OK. >> state->fp = (unsigned long)__builtin_frame_address(1); >> state->pc = (unsigned long)__builtin_return_address(0); >> @@ -87,7 +91,7 @@ static __always_inline void unwind_init_from_current(struct unwind_state *state) >> static inline void unwind_init_from_task(struct unwind_state *state, >> struct task_struct *task) >> { >> - unwind_init_common(state); >> + unwind_init_common(state, task); >> >> state->fp = thread_saved_fp(task); >> state->pc = thread_saved_pc(task); >> @@ -100,11 +104,11 @@ static inline void unwind_init_from_task(struct unwind_state *state, >> * records (e.g. a cycle), determined based on the location and fp value of A >> * and the location (but not the fp value) of B. >> */ >> -static int notrace unwind_next(struct task_struct *tsk, >> - struct unwind_state *state) >> +static int notrace unwind_next(struct unwind_state *state) >> { >> unsigned long fp = state->fp; >> struct stack_info info; >> + struct task_struct *tsk = state->task; >> >> /* Final frame; nothing to unwind */ >> if (fp == (unsigned long)task_pt_regs(tsk)->stackframe) >> @@ -176,8 +180,7 @@ static int notrace unwind_next(struct task_struct *tsk, >> } >> NOKPROBE_SYMBOL(unwind_next); >> >> -static void notrace unwind(struct task_struct *tsk, >> - struct unwind_state *state, >> +static void notrace unwind(struct unwind_state *state, >> bool (*fn)(void *, unsigned long), void *data) >> { >> while (1) { >> @@ -185,7 +188,7 @@ static void notrace unwind(struct task_struct *tsk, >> >> if (!fn(data, state->pc)) >> break; >> - ret = unwind_next(tsk, state); >> + ret = unwind_next(state); >> if (ret < 0) >> break; >> } >> @@ -232,11 +235,11 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry, >> struct unwind_state state; >> >> if (regs) >> - unwind_init_from_regs(&state, regs); >> + unwind_init_from_regs(&state, task, regs); >> else if (task == current) >> - unwind_init_from_current(&state); >> + unwind_init_from_current(&state, task); >> else >> unwind_init_from_task(&state, task); > > As above we shouldn't need these two changes. > > For the regs case we might want to sanity-check that task == current. > Will do. >> - unwind(task, &state, consume_entry, cookie); >> + unwind(&state, consume_entry, cookie); > > Otherwise, this looks good to me. Thanks. Madhavan
diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h index 41ec360515f6..af423f5d7ad8 100644 --- a/arch/arm64/include/asm/stacktrace.h +++ b/arch/arm64/include/asm/stacktrace.h @@ -51,6 +51,8 @@ struct stack_info { * @kr_cur: When KRETPROBES is selected, holds the kretprobe instance * associated with the most recently encountered replacement lr * value. + * + * @task: Pointer to the task structure. */ struct unwind_state { unsigned long fp; @@ -61,6 +63,7 @@ struct unwind_state { #ifdef CONFIG_KRETPROBES struct llist_node *kr_cur; #endif + struct task_struct *task; }; extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk, diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index b2b568e5deba..1b32e55735aa 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -33,8 +33,10 @@ */ -static void unwind_init_common(struct unwind_state *state) +static void unwind_init_common(struct unwind_state *state, + struct task_struct *task) { + state->task = task; #ifdef CONFIG_KRETPROBES state->kr_cur = NULL; #endif @@ -57,9 +59,10 @@ static void unwind_init_common(struct unwind_state *state) * TODO: document requirements here. */ static inline void unwind_init_from_regs(struct unwind_state *state, + struct task_struct *task, struct pt_regs *regs) { - unwind_init_common(state); + unwind_init_common(state, task); state->fp = regs->regs[29]; state->pc = regs->pc; @@ -71,9 +74,10 @@ static inline void unwind_init_from_regs(struct unwind_state *state, * Note: this is always inlined, and we expect our caller to be a noinline * function, such that this starts from our caller's caller. */ -static __always_inline void unwind_init_from_current(struct unwind_state *state) +static __always_inline void unwind_init_from_current(struct unwind_state *state, + struct task_struct *task) { - unwind_init_common(state); + unwind_init_common(state, task); state->fp = (unsigned long)__builtin_frame_address(1); state->pc = (unsigned long)__builtin_return_address(0); @@ -87,7 +91,7 @@ static __always_inline void unwind_init_from_current(struct unwind_state *state) static inline void unwind_init_from_task(struct unwind_state *state, struct task_struct *task) { - unwind_init_common(state); + unwind_init_common(state, task); state->fp = thread_saved_fp(task); state->pc = thread_saved_pc(task); @@ -100,11 +104,11 @@ static inline void unwind_init_from_task(struct unwind_state *state, * records (e.g. a cycle), determined based on the location and fp value of A * and the location (but not the fp value) of B. */ -static int notrace unwind_next(struct task_struct *tsk, - struct unwind_state *state) +static int notrace unwind_next(struct unwind_state *state) { unsigned long fp = state->fp; struct stack_info info; + struct task_struct *tsk = state->task; /* Final frame; nothing to unwind */ if (fp == (unsigned long)task_pt_regs(tsk)->stackframe) @@ -176,8 +180,7 @@ static int notrace unwind_next(struct task_struct *tsk, } NOKPROBE_SYMBOL(unwind_next); -static void notrace unwind(struct task_struct *tsk, - struct unwind_state *state, +static void notrace unwind(struct unwind_state *state, bool (*fn)(void *, unsigned long), void *data) { while (1) { @@ -185,7 +188,7 @@ static void notrace unwind(struct task_struct *tsk, if (!fn(data, state->pc)) break; - ret = unwind_next(tsk, state); + ret = unwind_next(state); if (ret < 0) break; } @@ -232,11 +235,11 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry, struct unwind_state state; if (regs) - unwind_init_from_regs(&state, regs); + unwind_init_from_regs(&state, task, regs); else if (task == current) - unwind_init_from_current(&state); + unwind_init_from_current(&state, task); else unwind_init_from_task(&state, task); - unwind(task, &state, consume_entry, cookie); + unwind(&state, consume_entry, cookie); }