On Fri, 7 Dec 2018 20:48:47 +0100
Borislav Petkov <bp@xxxxxxxxx> wrote:
> On Fri, Dec 07, 2018 at 11:42:10PM +0900, Masami Hiramatsu wrote:
> > Hmm, I just thought that the symbol only referred from inline asm should
> > be visible. But if it is OK for any version of supported gcc and clang,
> > I'm good to remove it. :-) (IOW, I just concerned about older gcc)
>
> I just tried two gcc versions: 8.2 and 4.8.5. Both asms looks good:
>
> ffffffff81044690 <kretprobe_trampoline>:
> ...
>
>
> ffffffff810446ab: 41 57 push %r15
> ffffffff810446ad: 48 89 e7 mov %rsp,%rdi
> ffffffff810446b0: e8 db 01 00 00 callq ffffffff81044890 <trampoline_handler>
>
> there's the CALL...
>
> ffffffff810446b5: 48 89 84 24 98 00 00 mov %rax,0x98(%rsp)
> ffffffff810446bc: 00
>
> ... and the handler is at the expected address.
>
> ffffffff81044890 <trampoline_handler>:
> ffffffff81044890: e8 ab c9 7b 00 callq ffffffff81801240 <__fentry__>
> ffffffff81044895: 41 57 push %r15
> ffffffff81044897: 41 56 push %r14
> ffffffff81044899: 41 55 push %r13
> ffffffff8104489b: 49 89 fd mov %rdi,%r13
>
> Dunno, if you feel like there might be some trouble with some compilers,
> I can keep the hunk below as a separate patch and revert it when it
> explodes somewhere...?
OK, then please remove it. :-) Even if any problem occurs, which must be
build error, so we can revert it in that case.
Thank you!
>
> > Reviewed-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> >
> > Thank you,
> >
> > >
> > > ---
> > > diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
> > > index 6480056d370f..308bf103cc73 100644
> > > --- a/arch/x86/kernel/kprobes/core.c
> > > +++ b/arch/x86/kernel/kprobes/core.c
> > > @@ -66,8 +66,6 @@
> > >
> > > #include "common.h"
> > >
> > > -void *trampoline_handler(struct pt_regs *regs);
> > > -
> > > DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
> > > DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
> > >
> > > @@ -753,7 +751,7 @@ STACK_FRAME_NON_STANDARD(kretprobe_trampoline);
> > > /*
> > > * Called from kretprobe_trampoline
> > > */
> > > -__visible __used void *trampoline_handler(struct pt_regs *regs)
> > > +static __used void *trampoline_handler(struct pt_regs *regs)
> > > {
> > > struct kretprobe_instance *ri = NULL;
> > > struct hlist_head *head, empty_rp;
> > >
> > > --
> > > Regards/Gruss,
> > > Boris.
> > >
> > > Good mailing practices for 400: avoid top-posting and trim the reply.
> >
> >
> > --
> > Masami Hiramatsu <mhiramat@xxxxxxxxxx>
>
> --
> Regards/Gruss,
> Boris.
>
> Good mailing practices for 400: avoid top-posting and trim the reply.
--
Masami Hiramatsu <mhiramat@xxxxxxxxxx>
