Messages in this thread | | | Date | Fri, 9 Jan 2015 13:19:50 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH 3/4] x86: open-code register save/restore in trace_hardirqs thunks |
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On Thu, Jan 08, 2015 at 05:25:14PM +0100, Denys Vlasenko wrote: > This is a preparatory patch for change in "struct pt_regs" > handling in entry_64.S. > > trace_hardirqs thunks were (ab)using a part of pt_regs > handling code, namely SAVE_ARGS/RESTORE_ARGS macros, > to save/restore registers across C function calls. > > Since SAVE_ARGS is going to be changed, open-code > register saving/restoring here. > > Incidentally, this removes a bit of dead code: > one SAVE_ARGS was used just to emit a CFI annotation, > but it also generated unreachable assembly insns. > > Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com> > CC: Linus Torvalds <torvalds@linux-foundation.org> > CC: Oleg Nesterov <oleg@redhat.com> > CC: "H. Peter Anvin" <hpa@zytor.com> > CC: Andy Lutomirski <luto@amacapital.net> > CC: Frederic Weisbecker <fweisbec@gmail.com> > CC: X86 ML <x86@kernel.org> > CC: Alexei Starovoitov <ast@plumgrid.com> > CC: Will Drewry <wad@chromium.org> > CC: Kees Cook <keescook@chromium.org> > CC: linux-kernel@vger.kernel.org > --- > arch/x86/lib/thunk_64.S | 29 ++++++++++++++++++++++++----- > 1 file changed, 24 insertions(+), 5 deletions(-)
Hmm, this patch breaks booting my kvm guest: it stops booting at some point and restarts itself after a couple of seconds.
The monitor says rIP points to ffffffff8167ae30 which is this:
ffffffff8167ae30 <async_page_fault>: ffffffff8167ae30: ff 15 fa 62 31 00 callq *0x3162fa(%rip) # ffffffff81991130 <pv_irq_ops+0x30> ffffffff8167ae36: 48 83 ec 78 sub $0x78,%rsp ffffffff8167ae3a: e8 d1 01 00 00 callq ffffffff8167b010 <error_entry> ffffffff8167ae3f: 48 89 e7 mov %rsp,%rdi ffffffff8167ae42: 48 8b 74 24 78 mov 0x78(%rsp),%rsi ffffffff8167ae47: 48 c7 44 24 78 ff ff movq $0xffffffffffffffff,0x78(%rsp) ffffffff8167ae4e: ff ff ffffffff8167ae50: e8 9b 9e 9c ff callq ffffffff81044cf0 <do_async_page_fault> ffffffff8167ae55: e9 76 02 00 00 jmpq ffffffff8167b0d0 <error_exit> ffffffff8167ae5a: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1)
HTH.
-- Regards/Gruss, Boris.
Sent from a fat crate under my desk. Formatting is fine. --
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