This allows to remove "addq $8, %rsp" from five of six execve and sigreturn
stubs.
More importantly, it enables next optimization: faster return on execve failure.
Run-tested.
Signed-off-by: Denys Vlasenko <dvlas...@redhat.com>
CC: Linus Torvalds <torva...@linux-foundation.org>
CC: Steven Rostedt <rost...@goodmis.org>
CC: Ingo Molnar <mi...@kernel.org>
CC: Borislav Petkov <b...@alien8.de>
CC: "H. Peter Anvin" <h...@zytor.com>
CC: Andy Lutomirski <l...@amacapital.net>
CC: Oleg Nesterov <o...@redhat.com>
CC: Frederic Weisbecker <fweis...@gmail.com>
CC: Alexei Starovoitov <a...@plumgrid.com>
CC: Will Drewry <w...@chromium.org>
CC: Kees Cook <keesc...@chromium.org>
CC: x...@kernel.org
CC: linux-kernel@vger.kernel.org
---
arch/x86/kernel/entry_64.S | 27 +++++++++++----------------
1 file changed, 11 insertions(+), 16 deletions(-)
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 1cf245d..060cb2e 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -418,11 +418,11 @@ END(stub_\func)
ENTRY(stub_execve)
CFI_STARTPROC
- addq $8, %rsp
- DEFAULT_FRAME 0
- SAVE_EXTRA_REGS
+ DEFAULT_FRAME 0, 8
+ SAVE_EXTRA_REGS 8
call sys_execve
return_from_stub:
+ addq $8, %rsp
movq %rax,RAX(%rsp)
RESTORE_EXTRA_REGS
jmp int_ret_from_sys_call
@@ -431,9 +431,8 @@ END(stub_execve)
ENTRY(stub_execveat)
CFI_STARTPROC
- addq $8, %rsp
- DEFAULT_FRAME 0
- SAVE_EXTRA_REGS
+ DEFAULT_FRAME 0, 8
+ SAVE_EXTRA_REGS 8
call sys_execveat
jmp return_from_stub
CFI_ENDPROC
@@ -445,8 +444,7 @@ END(stub_execveat)
*/
ENTRY(stub_rt_sigreturn)
CFI_STARTPROC
- addq $8, %rsp
- DEFAULT_FRAME 0
+ DEFAULT_FRAME 0, 8
/*
* Despite RESTORE_EXTRA_REGS in return_from_stub,
* no need to SAVE_EXTRA_REGS here:
@@ -461,8 +459,7 @@ END(stub_rt_sigreturn)
#ifdef CONFIG_X86_X32_ABI
ENTRY(stub_x32_rt_sigreturn)
CFI_STARTPROC
- addq $8, %rsp
- DEFAULT_FRAME 0
+ DEFAULT_FRAME 0, 8
/* No need to SAVE_EXTRA_REGS */
call sys32_x32_rt_sigreturn
jmp return_from_stub
@@ -471,9 +468,8 @@ END(stub_x32_rt_sigreturn)
ENTRY(stub_x32_execve)
CFI_STARTPROC
- addq $8, %rsp
- DEFAULT_FRAME 0
- SAVE_EXTRA_REGS
+ DEFAULT_FRAME 0, 8
+ SAVE_EXTRA_REGS 8
call compat_sys_execve
jmp return_from_stub
CFI_ENDPROC
@@ -481,9 +477,8 @@ END(stub_x32_execve)
ENTRY(stub_x32_execveat)
CFI_STARTPROC
- addq $8, %rsp
- DEFAULT_FRAME 0
- SAVE_EXTRA_REGS
+ DEFAULT_FRAME 0, 8
+ SAVE_EXTRA_REGS 8
call compat_sys_execveat
jmp return_from_stub
CFI_ENDPROC
--
1.8.1.4
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