| Message ID | 162400000592.506599.4695807810528866713.stgit@devnote2 (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | kprobes: Fix stacktrace with kretprobes on x86 | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
On Fri, Jun 18, 2021 at 04:06:46PM +0900, Masami Hiramatsu wrote: > 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). > > Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com> > Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> > Tested-by: Andrii Nakryik <andrii@kernel.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> > --- > Changes in v8: > - Update comment to clarify why this is needed. > Changes in v3: > - Cast the correct_ret_addr to unsigned long. > --- > kernel/kprobes.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index 650cbe738666..ba729ed05cb3 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -1896,6 +1896,9 @@ unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, > BUG_ON(1); > } > > + /* Set the instruction pointer to the correct address */ > + instruction_pointer_set(regs, (unsigned long)correct_ret_addr); > + > /* Run them. */ > first = current->kretprobe_instances.first; > while (first) { >
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 650cbe738666..ba729ed05cb3 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1896,6 +1896,9 @@ unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, BUG_ON(1); } + /* Set the instruction pointer to the correct address */ + instruction_pointer_set(regs, (unsigned long)correct_ret_addr); + /* Run them. */ first = current->kretprobe_instances.first; while (first) {