On Sat, 20 Mar 2021 21:16:16 +0900 Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote: > On Fri, 19 Mar 2021 21:22:39 +0900 > Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote: > > > From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> > > > > Add UNWIND_HINT_FUNC on kretporbe_trampoline code so that ORC > > information is generated on the kretprobe_trampoline correctly. > > > > Test bot also found a new warning for this. > > > >> arch/x86/kernel/kprobes/core.o: warning: objtool: kretprobe_trampoline()+0x25: call without frame pointer save/setup > > With CONFIG_FRAME_POINTER=y. > > Of course this can be fixed with additional "push %bp; mov %sp, %bp" before calling > trampoline_handler. But actually we know that this function has a bit special > stack frame too. > > Can I recover STACK_FRAME_NON_STANDARD(kretprobe_trampoline) when CONFIG_FRAME_POINTER=y ? So something like this. Does it work? diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index b31058a152b6..651f337dc880 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -760,6 +760,10 @@ int kprobe_int3_handler(struct pt_regs *regs) } NOKPROBE_SYMBOL(kprobe_int3_handler); +#ifdef CONFIG_FRAME_POINTER +#undef UNWIND_HINT_FUNC +#define UNWIND_HINT_FUNC +#endif /* * When a retprobed function returns, this code saves registers and * calls trampoline_handler() runs, which calls the kretprobe's handler. @@ -797,7 +801,14 @@ asm( ".size kretprobe_trampoline, .-kretprobe_trampoline\n" ); NOKPROBE_SYMBOL(kretprobe_trampoline); - +#ifdef CONFIG_FRAME_POINTER +/* + * kretprobe_trampoline skips updating frame pointer. The frame pointer + * saved in trampoline_handler points to the real caller function's + * frame pointer. + */ +STACK_FRAME_NON_STANDARD(kretprobe_trampoline); +#endif /* * Called from kretprobe_trampoline -- Masami Hiramatsu <mhiramat@xxxxxxxxxx>
