A stack frame pointer may be used in a different way depending on cpu architecture. Thus it is not always appropriate to slurp the stack contents, as currently done in check_stack(), in order to calcurate a stack index (height) at a given function call. At least not on arm64.
This patch extract potentially arch-specific code from check_stack() and puts it into a new arch_check_stack(), which is declared as weak. So we will be able to add arch-specific and most efficient way of stack traversing Later. Signed-off-by: AKASHI Takahiro <[email protected]> --- include/linux/stacktrace.h | 4 ++ kernel/trace/trace_stack.c | 88 ++++++++++++++++++++++++++------------------ 2 files changed, 56 insertions(+), 36 deletions(-) diff --git a/include/linux/stacktrace.h b/include/linux/stacktrace.h index 0a34489..bfae605 100644 --- a/include/linux/stacktrace.h +++ b/include/linux/stacktrace.h @@ -10,6 +10,10 @@ struct pt_regs; struct stack_trace { unsigned int nr_entries, max_entries; unsigned long *entries; +#ifdef CONFIG_STACK_TRACER + unsigned *index; + unsigned long *sp; +#endif int skip; /* input argument: How many entries to skip */ }; diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c index 3d9356b..021b8c3 100644 --- a/kernel/trace/trace_stack.c +++ b/kernel/trace/trace_stack.c @@ -27,9 +27,10 @@ static unsigned stack_dump_index[STACK_TRACE_ENTRIES]; * us to remove most or all of the stack size overhead * added by the stack tracer itself. */ -static struct stack_trace max_stack_trace = { + struct stack_trace max_stack_trace = { .max_entries = STACK_TRACE_ENTRIES - 1, .entries = &stack_dump_trace[0], + .index = &stack_dump_index[0], }; static unsigned long max_stack_size; @@ -65,42 +66,15 @@ static inline void print_max_stack(void) } } -static inline void -check_stack(unsigned long ip, unsigned long *stack) +void __weak +arch_check_stack(unsigned long ip, unsigned long *stack, + unsigned long *max_size, unsigned int *tracer_size) { - unsigned long this_size, flags; unsigned long *p, *top, *start; - static int tracer_frame; - int frame_size = ACCESS_ONCE(tracer_frame); + unsigned long *p, *top, *start; + unsigned long this_size; int i, x; - this_size = ((unsigned long)stack) & (THREAD_SIZE-1); - this_size = THREAD_SIZE - this_size; - /* Remove the frame of the tracer */ - this_size -= frame_size; - - if (this_size <= max_stack_size) - return; - - /* we do not handle interrupt stacks yet */ - if (!object_is_on_stack(stack)) - return; - - local_irq_save(flags); - arch_spin_lock(&max_stack_lock); - - /* In case another CPU set the tracer_frame on us */ - if (unlikely(!frame_size)) - this_size -= tracer_frame; - - /* a race could have already updated it */ - if (this_size <= max_stack_size) - goto out; - - max_stack_size = this_size; - - max_stack_trace.nr_entries = 0; max_stack_trace.skip = 3; - save_stack_trace(&max_stack_trace); /* Skip over the overhead of the stack tracer itself */ @@ -116,6 +90,7 @@ check_stack(unsigned long ip, unsigned long *stack) start = stack; top = (unsigned long *) (((unsigned long)start & ~(THREAD_SIZE-1)) + THREAD_SIZE); + this_size = *max_size; /* * Loop through all the entries. One of the entries may @@ -146,10 +121,10 @@ check_stack(unsigned long ip, unsigned long *stack) * out what that is, then figure it out * now. */ - if (unlikely(!tracer_frame)) { - tracer_frame = (p - stack) * + if (unlikely(!*tracer_size)) { + *tracer_size = (p - stack) * sizeof(unsigned long); - max_stack_size -= tracer_frame; + *max_size -= *tracer_size; } } } @@ -161,6 +136,47 @@ check_stack(unsigned long ip, unsigned long *stack) max_stack_trace.nr_entries = x; for (; x < i; x++) stack_dump_trace[x] = ULONG_MAX; +} + +static inline void +check_stack(unsigned long ip, unsigned long *stack) +{ + unsigned long this_size, flags; + static int tracer_frame; + int frame_size = ACCESS_ONCE(tracer_frame); + + this_size = ((unsigned long)stack) & (THREAD_SIZE-1); + this_size = THREAD_SIZE - this_size; + /* for safety, depending on arch_check_stack() */ + if (this_size < frame_size) + return; + + /* Remove the frame of the tracer */ + this_size -= frame_size; + + if (this_size <= max_stack_size) + return; + + /* we do not handle interrupt stacks yet */ + if (!object_is_on_stack(stack)) + return; + + local_irq_save(flags); + arch_spin_lock(&max_stack_lock); + + /* In case another CPU set the tracer_frame on us */ + if (unlikely(!frame_size)) + this_size -= tracer_frame; + + /* a race could have already updated it */ + if (this_size <= max_stack_size) + goto out; + + max_stack_size = this_size; + + max_stack_trace.nr_entries = 0; + + arch_check_stack(ip, stack, &max_stack_size, &tracer_frame); if (task_stack_end_corrupted(current)) { print_max_stack(); -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
