From d81675b60d0959cfa3727f03d5b90558fb457011 Mon Sep 17 00:00:00 2001 From: Vasily Gorbik Date: Wed, 28 Apr 2021 16:29:40 +0200 Subject: [PATCH] s390/unwind: recover kretprobe modified return address in stacktrace Based on commit cd9bc2c92588 ("arm64: Recover kretprobe modified return address in stacktrace"). """ Since the kretprobe replaces the function return address with the __kretprobe_trampoline on the stack, stack unwinder shows it instead of the correct return address. This checks whether the next return address is the __kretprobe_trampoline(), and if so, try to find the correct return address from the kretprobe instance list. """ Original patch series: https://lore.kernel.org/all/163163030719.489837.2236069935502195491.stgit@devnote2/ Reviewed-by: Tobias Huschle Signed-off-by: Vasily Gorbik --- arch/s390/include/asm/unwind.h | 13 +++++++++++++ arch/s390/kernel/unwind_bc.c | 8 ++------ 2 files changed, 15 insertions(+), 6 deletions(-) diff --git a/arch/s390/include/asm/unwind.h b/arch/s390/include/asm/unwind.h index 5ebf534..0bf06f1 100644 --- a/arch/s390/include/asm/unwind.h +++ b/arch/s390/include/asm/unwind.h @@ -4,6 +4,8 @@ #include #include +#include +#include #include #include @@ -36,10 +38,21 @@ struct unwind_state { struct pt_regs *regs; unsigned long sp, ip; int graph_idx; + struct llist_node *kr_cur; bool reliable; bool error; }; +/* Recover the return address modified by kretprobe and ftrace_graph. */ +static inline unsigned long unwind_recover_ret_addr(struct unwind_state *state, + unsigned long ip) +{ + ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, ip, NULL); + if (is_kretprobe_trampoline(ip)) + ip = kretprobe_find_ret_addr(state->task, (void *)state->sp, &state->kr_cur); + return ip; +} + void __unwind_start(struct unwind_state *state, struct task_struct *task, struct pt_regs *regs, unsigned long first_frame); bool unwind_next_frame(struct unwind_state *state); diff --git a/arch/s390/kernel/unwind_bc.c b/arch/s390/kernel/unwind_bc.c index 707fd99..9849703 100644 --- a/arch/s390/kernel/unwind_bc.c +++ b/arch/s390/kernel/unwind_bc.c @@ -103,13 +103,11 @@ bool unwind_next_frame(struct unwind_state *state) if (sp & 0x7) goto out_err; - ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, ip, (void *) sp); - /* Update unwind state */ state->sp = sp; - state->ip = ip; state->regs = regs; state->reliable = reliable; + state->ip = unwind_recover_ret_addr(state, ip); return true; out_err: @@ -161,12 +159,10 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task, ip = READ_ONCE_NOCHECK(sf->gprs[8]); } - ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, ip, NULL); - /* Update unwind state */ state->sp = sp; - state->ip = ip; state->reliable = true; + state->ip = unwind_recover_ret_addr(state, ip); if (!first_frame) return; -- 2.7.4