linux/arch/x86/vdso/vdso32
Denys Vlasenko e7d6eefaaa x86/vdso32/syscall.S: Do not load __USER32_DS to %ss
This vDSO code only gets used by 64-bit kernels, not 32-bit ones.

On 64-bit kernels, the data segment is the same for 32-bit and
64-bit userspace, and the SYSRET instruction loads %ss with its
selector.

So there's no need to repeat it by hand. Segment loads are somewhat
expensive: tens of cycles.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
[ Removed unnecessary comment. ]
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/63da6d778f69fd0f1345d9287f6764d58be519fa.1427482099.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-31 10:45:15 +02:00
..
.gitignore x86: gitignore arch/x86/vdso files 2008-01-30 13:32:32 +01:00
int80.S x86 vDSO: canonicalize sysenter .eh_frame 2008-01-30 13:30:44 +01:00
note.S x86 vDSO: i386 vdso32 2008-01-30 13:30:42 +01:00
sigreturn.S x86/vdso: Fix the build on GCC5 2015-03-06 09:34:45 +01:00
syscall.S x86/vdso32/syscall.S: Do not load __USER32_DS to %ss 2015-03-31 10:45:15 +02:00
sysenter.S x86-32, vdso: On system call restart after SYSENTER, use int $0x80 2011-08-23 16:20:10 -07:00
vclock_gettime.c x86, vdso: Add 32 bit VDSO time support for 64 bit kernel 2014-03-18 12:52:41 -07:00
vdso32.lds.S x86, vdso: Remove vestiges of VDSO_PRELINK and some outdated comments 2014-05-05 13:19:07 -07:00
vdso-fakesections.c x86/vdso: Improve the fake section headers 2014-06-19 15:45:12 -07:00