From 9e09d445f1cab518eedf4454d119ead27979b8f4 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Tue, 11 Apr 2023 17:29:41 +0100 Subject: [PATCH] arm64: stacktrace: recover return address for first entry The function which calls the top-level backtracing function may have been instrumented with ftrace and/or kprobes, and hence the first return address may have been rewritten. Factor out the existing fgraph / kretprobes address recovery, and use this for the first address. As the comment for the fgraph case isn't all that helpful, I've also dropped that. Signed-off-by: Mark Rutland Reviewed-by: Kalesh Singh Cc: Catalin Marinas Cc: Madhavan T. Venkataraman Cc: Mark Brown Cc: Will Deacon Link: https://lore.kernel.org/r/20230411162943.203199-2-mark.rutland@arm.com Signed-off-by: Will Deacon --- arch/arm64/kernel/stacktrace.c | 53 ++++++++++++++++++++++++------------------ 1 file changed, 30 insertions(+), 23 deletions(-) diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index 8315430..dd03feb 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -69,6 +69,32 @@ static __always_inline void unwind_init_from_task(struct unwind_state *state, state->pc = thread_saved_pc(task); } +static __always_inline int +unwind_recover_return_address(struct unwind_state *state) +{ +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + if (state->task->ret_stack && + (state->pc == (unsigned long)return_to_handler)) { + unsigned long orig_pc; + orig_pc = ftrace_graph_ret_addr(state->task, NULL, state->pc, + (void *)state->fp); + if (WARN_ON_ONCE(state->pc == orig_pc)) + return -EINVAL; + state->pc = orig_pc; + } +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ + +#ifdef CONFIG_KRETPROBES + if (is_kretprobe_trampoline(state->pc)) { + state->pc = kretprobe_find_ret_addr(state->task, + (void *)state->fp, + &state->kr_cur); + } +#endif /* CONFIG_KRETPROBES */ + + return 0; +} + /* * Unwind from one frame record (A) to the next frame record (B). * @@ -92,35 +118,16 @@ static int notrace unwind_next(struct unwind_state *state) state->pc = ptrauth_strip_insn_pac(state->pc); -#ifdef CONFIG_FUNCTION_GRAPH_TRACER - if (tsk->ret_stack && - (state->pc == (unsigned long)return_to_handler)) { - unsigned long orig_pc; - /* - * This is a case where function graph tracer has - * modified a return address (LR) in a stack frame - * to hook a function return. - * So replace it to an original value. - */ - orig_pc = ftrace_graph_ret_addr(tsk, NULL, state->pc, - (void *)state->fp); - if (WARN_ON_ONCE(state->pc == orig_pc)) - return -EINVAL; - state->pc = orig_pc; - } -#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ -#ifdef CONFIG_KRETPROBES - if (is_kretprobe_trampoline(state->pc)) - state->pc = kretprobe_find_ret_addr(tsk, (void *)state->fp, &state->kr_cur); -#endif - - return 0; + return unwind_recover_return_address(state); } NOKPROBE_SYMBOL(unwind_next); static void notrace unwind(struct unwind_state *state, stack_trace_consume_fn consume_entry, void *cookie) { + if (unwind_recover_return_address(state)) + return; + while (1) { int ret; -- 2.7.4