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 <huschle@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

1 files changed, 2 insertions, 6 deletions

diff --git a/arch/s390/kernel/unwind_bc.c b/arch/s390/kernel/unwind_bc.c
index 707fd99f6734..984970389bab 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;