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authorMasami Hiramatsu <mhiramat@kernel.org>2021-09-14 23:42:12 +0900
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2021-09-30 21:24:07 -0400
commitdf91c5bccb0c2cb868b54bd68a6ddf1fcbede6b1 (patch)
treea59ebf2643820e0c4a7928e667f9b86fc77a7a7c /kernel/kprobes.c
parent7391dd19027cec4e0edf81b7c27079ae0ecd2d6b (diff)
kprobes: Enable stacktrace from pt_regs in kretprobe handler
Since the ORC unwinder from pt_regs requires setting up regs->ip correctly, set the correct return address to the regs->ip before calling user kretprobe handler. This allows the kretrprobe handler to trace stack from the kretprobe's pt_regs by stack_trace_save_regs() (eBPF will do this), instead of stack tracing from the handler context by stack_trace_save() (ftrace will do this). Link: https://lkml.kernel.org/r/163163053237.489837.4272653874525136832.stgit@devnote2 Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Tested-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/kprobes.c')
-rw-r--r--kernel/kprobes.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 833f07f33115..ebc587b9a346 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1937,6 +1937,13 @@ unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
BUG_ON(1);
}
+ /*
+ * Set the return address as the instruction pointer, because if the
+ * user handler calls stack_trace_save_regs() with this 'regs',
+ * the stack trace will start from the instruction pointer.
+ */
+ instruction_pointer_set(regs, (unsigned long)correct_ret_addr);
+
/* Run the user handler of the nodes. */
first = current->kretprobe_instances.first;
while (first) {