Messages in this thread |  | | From | Andy Lutomirski <> | | Date | Mon, 27 Jul 2015 15:37:34 -0700 | | Subject | Re: [PATCH 3/5] x86/asm/entry/32: Jump from SYSENTER32 to SYSCALL32 code path |
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> Subject: [PATCH 3/5] x86/asm/entry/32: Jump from SYSENTER32 to SYSCALL32 code path
Shouldn't that be /64, not /32, or maybe /64/compat?
On Mon, Jul 27, 2015 at 1:33 PM, Denys Vlasenko <dvlasenk@redhat.com> wrote: > In 32-bit SYSENTER code, load arg6 into R9 instead of EBP. > Jump to SYSCALL code path after we finish setting up pt_regs > and clearing FLAGS_NT. > > This leaves most of SYSENTER32 code path inaccessible. > > Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com> > CC: Ingo Molnar <mingo@kernel.org> > CC: Linus Torvalds <torvalds@linux-foundation.org> > CC: Krzysztof A. Sobiecki <sobkas@gmail.com> > CC: Steven Rostedt <rostedt@goodmis.org> > CC: Borislav Petkov <bp@alien8.de> > CC: "H. Peter Anvin" <hpa@zytor.com> > CC: Andy Lutomirski <luto@amacapital.net> > CC: Oleg Nesterov <oleg@redhat.com> > CC: Frederic Weisbecker <fweisbec@gmail.com> > CC: Alexei Starovoitov <ast@plumgrid.com> > CC: Will Drewry <wad@chromium.org> > CC: Kees Cook <keescook@chromium.org> > CC: x86@kernel.org > CC: linux-kernel@vger.kernel.org > --- > arch/x86/entry/entry_64_compat.S | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S > index df102e8..d74745a 100644 > --- a/arch/x86/entry/entry_64_compat.S > +++ b/arch/x86/entry/entry_64_compat.S > @@ -93,7 +93,7 @@ ENTRY(entry_SYSENTER_compat) > * 32-bit zero extended > */ > ASM_STAC > -1: movl (%rbp), %ebp > +1: movl (%rbp), %r9d
You're sticking arg6 into r9d here, I think, and then:
> > orl $TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS) > testl $_TIF_WORK_SYSCALL_ENTRY, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) > @@ -343,6 +344,7 @@ ENTRY(entry_SYSCALL_compat) > _ASM_EXTABLE(1b, ia32_badarg) > ASM_CLAC > > +sysenter_jumps_here: > orl $TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS) > testl $_TIF_WORK_SYSCALL_ENTRY, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) > jnz cstar_tracesys
you land here, which eventually does:
movl %ebp, %r9d /* arg6 */
What am I missing?
--Andy
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