On arm64, no PC values returned by save_stack_trace() will match to LR values saved in stack frames on a stack after the following commit: commit e306dfd06fcb ("ARM64: unwind: Fix PC calculation") As a result, the output from stack tracer will be messed up.
This patch introduces an arch-defined macro, FTRACE_STACK_FRAME_OFFSET, so that check_stack() can handle this case correctly. Signed-off-by: AKASHI Takahiro <takahiro.aka...@linaro.org> --- arch/arm64/include/asm/ftrace.h | 5 +++-- arch/arm64/kernel/stacktrace.c | 7 ++++--- include/linux/ftrace.h | 7 +++++++ kernel/trace/trace_stack.c | 5 +++-- 4 files changed, 17 insertions(+), 7 deletions(-) diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h index c5534fa..2b43e20 100644 --- a/arch/arm64/include/asm/ftrace.h +++ b/arch/arm64/include/asm/ftrace.h @@ -13,8 +13,9 @@ #include <asm/insn.h> -#define MCOUNT_ADDR ((unsigned long)_mcount) -#define MCOUNT_INSN_SIZE AARCH64_INSN_SIZE +#define MCOUNT_ADDR ((unsigned long)_mcount) +#define MCOUNT_INSN_SIZE AARCH64_INSN_SIZE +#define FTRACE_STACK_FRAME_OFFSET AARCH64_INSN_SIZE #ifndef __ASSEMBLY__ #include <linux/compat.h> diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index 407991b..bc0689a 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -20,6 +20,7 @@ #include <linux/sched.h> #include <linux/stacktrace.h> +#include <asm/insn.h> #include <asm/stacktrace.h> /* @@ -49,10 +50,10 @@ int notrace unwind_frame(struct stackframe *frame) frame->sp = fp + 0x10; frame->fp = *(unsigned long *)(fp); /* - * -4 here because we care about the PC at time of bl, - * not where the return will go. + * decrement PC by AARCH64_INSN_SIZE here because we care about + * the PC at time of bl, not where the return will go. */ - frame->pc = *(unsigned long *)(fp + 8) - 4; + frame->pc = *(unsigned long *)(fp + 8) - AARCH64_INSN_SIZE; return 0; } diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 6cd8c0e..d77b195 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -263,6 +263,13 @@ static inline void ftrace_kill(void) { } #endif /* CONFIG_FUNCTION_TRACER */ #ifdef CONFIG_STACK_TRACER +/* + * the offset value to add to return address from save_stack_trace() + */ +#ifndef FTRACE_STACK_FRAME_OFFSET +#define FTRACE_STACK_FRAME_OFFSET 0 +#endif + extern int stack_tracer_enabled; int stack_trace_sysctl(struct ctl_table *table, int write, diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c index b746399..30521ea 100644 --- a/kernel/trace/trace_stack.c +++ b/kernel/trace/trace_stack.c @@ -105,7 +105,7 @@ check_stack(unsigned long ip, unsigned long *stack) /* Skip over the overhead of the stack tracer itself */ for (i = 0; i < max_stack_trace.nr_entries; i++) { - if (stack_dump_trace[i] == ip) + if ((stack_dump_trace[i] + FTRACE_STACK_FRAME_OFFSET) == ip) break; } @@ -133,7 +133,8 @@ check_stack(unsigned long ip, unsigned long *stack) for (; p < top && i < max_stack_trace.nr_entries; p++) { if (stack_dump_trace[i] == ULONG_MAX) break; - if (*p == stack_dump_trace[i]) { + if (*p == (stack_dump_trace[i] + + FTRACE_STACK_FRAME_OFFSET)) { stack_dump_trace[x] = stack_dump_trace[i++]; this_size = stack_dump_index[x++] = (top - p) * sizeof(unsigned long); -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/