Function graph tracer modifies a saved lr register on stack in order to hook a function return. This results in finding many bogus entries in a stack trace list.
This patch replaces such entries with originals values stored in current->ret_stack[]. Signed-off-by: AKASHI Takahiro <[email protected]> --- arch/arm64/kernel/stacktrace.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index 496ab0f..d1790eb 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -100,6 +100,28 @@ static void notrace arm64_stack_index(struct stackframe *frame, /* should not go beyond this frame */ if (trace->index[x] == THREAD_SIZE) trace->index[x] = 0; + + if (trace->entries[x] == + ((unsigned long)return_to_handler + 0x8)) { + /* + * This is a case where return_to_handler() is calling + * ftrace_return_to_handler(). As we are already on + * an original function's stack, we have no way to fetch + * a correct pc value, just skip it. + */ + trace->entries[x] = 0x0; + } else if (trace->entries[x] == + (unsigned long)return_to_handler - AARCH64_INSN_SIZE) { + /* + * This is a case where function graph tracer has + * modified lr register on a stack to hook a function + * return. + * So replace it to original value. + */ + trace->entries[x] = + current->ret_stack[data->ret_stack_index--].ret + - AARCH64_INSN_SIZE; + } } #endif /* CONFIG_STACK_TRACER */ -- 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/
