diff options
| author | Denys Vlasenko <dvlasenk@redhat.com> | 2015-02-26 22:40:38 (GMT) |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-03-04 21:50:52 (GMT) |
| commit | d441c1f2b73ec742c2e55be804ebc6fee130c77f (patch) | |
| tree | f7e1cee1c0507c57368e582c9eacc7c26dc96467 /arch/x86/kernel | |
| parent | b3ab90b333e94659e7c351843ab41ec0004f73e8 (diff) | |
| download | linux-d441c1f2b73ec742c2e55be804ebc6fee130c77f.tar.xz | |
x86/asm/entry/64: Simplify optimistic SYSRET
Avoid redundant load of %r11 (it is already loaded a few
instructions before).
Also simplify %rsp restoration, instead of two steps:
add $0x80, %rsp
mov 0x18(%rsp), %rsp
we can do a simplified single step to restore user-space RSP:
mov 0x98(%rsp), %rsp
and get the same result.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
[ Clarified the changelog. ]
Cc: Alexei Starovoitov <ast@plumgrid.com>
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: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1aef69b346a6db0d99cdfb0f5ba83e8c985e27d7.1424989793.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/entry_64.S | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 858e94e..bc15278 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -757,9 +757,9 @@ retint_swapgs: /* return to user-space */ */ irq_return_via_sysret: CFI_REMEMBER_STATE - RESTORE_C_REGS - REMOVE_PT_GPREGS_FROM_STACK 8 - movq (RSP-RIP)(%rsp),%rsp + /* r11 is already restored (see code above) */ + RESTORE_C_REGS_EXCEPT_R11 + movq RSP(%rsp),%rsp USERGS_SYSRET64 CFI_RESTORE_STATE |