On Mon, 21 Mar 2022 17:48:54 +0100 Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > On Mon, Mar 21, 2022 at 02:04:05PM +0100, Peter Zijlstra wrote: > > On Mon, Mar 21, 2022 at 01:55:49PM +0100, Peter Zijlstra wrote: > > > On Mon, Mar 21, 2022 at 02:03:27PM +1100, Stephen Rothwell wrote: > > > > Hi all, > > > > > > > > After merging the tip tree, today's linux-next build (x864 allmodconfig) > > > > produced these new warnings: > > > > > > > > vmlinux.o: warning: objtool: arch_rethook_prepare()+0x55: relocation to !ENDBR: arch_rethook_trampoline+0x0 > > > > vmlinux.o: warning: objtool: arch_rethook_trampoline_callback()+0x3e: relocation to !ENDBR: arch_rethook_trampoline+0x0 > > > > vmlinux.o: warning: objtool: unwind_next_frame()+0x93e: relocation to !ENDBR: arch_rethook_trampoline+0x0 > > > > vmlinux.o: warning: objtool: unwind_next_frame()+0x5f2: relocation to !ENDBR: arch_rethook_trampoline+0x0 > > > > vmlinux.o: warning: objtool: unwind_next_frame()+0x4a7: relocation to !ENDBR: arch_rethook_trampoline+0x0 > > > > vmlinux.o: warning: objtool: __rethook_find_ret_addr()+0x81: relocation to !ENDBR: arch_rethook_trampoline+0x0 > > > > vmlinux.o: warning: objtool: __rethook_find_ret_addr()+0x90: relocation to !ENDBR: arch_rethook_trampoline+0x0 > > > > vmlinux.o: warning: objtool: rethook_trampoline_handler()+0x8c: relocation to !ENDBR: arch_rethook_trampoline+0x0 > > > > vmlinux.o: warning: objtool: rethook_trampoline_handler()+0x9b: relocation to !ENDBR: arch_rethook_trampoline+0x0 > > > > > > Hurmph, lemme go figure out where that code comes from, I've not seen > > > those. > > > > Ahh, something tracing. I'll go do some patches on top of it. > > The below gets rid of the objtool warnings. Yes, I confirmed that. > > But I still think it's fairly terrible to get a (flawed) carbon copy of > the kretprobe code. Indeed. I would like to replace the trampoline code of kretprobe with rethook, eventually. There is no reason why we keep the clone. (But I need more arch maintainers help for that, there are too many archs implemented kretprobes) > Also, I think both should fix regs->ss. I'm not sure this part. Since the return trampoline should run in the same context of the called function, isn't ss same there too? Thank you, > > --- > diff --git a/arch/x86/kernel/rethook.c b/arch/x86/kernel/rethook.c > index f0f2f0608282..227a1890a984 100644 > --- a/arch/x86/kernel/rethook.c > +++ b/arch/x86/kernel/rethook.c > @@ -20,6 +20,7 @@ asm( > ".type arch_rethook_trampoline, @function\n" > "arch_rethook_trampoline:\n" > #ifdef CONFIG_X86_64 > + ANNOTATE_NOENDBR > /* Push a fake return address to tell the unwinder it's a kretprobe. */ > " pushq $arch_rethook_trampoline\n" > UNWIND_HINT_FUNC > @@ -48,7 +49,7 @@ asm( > " addl $4, %esp\n" > " popfl\n" > #endif > - " ret\n" > + ASM_RET > ".size arch_rethook_trampoline, .-arch_rethook_trampoline\n" > ); > NOKPROBE_SYMBOL(arch_rethook_trampoline); -- Masami Hiramatsu <mhiramat@xxxxxxxxxx>
