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 <[email protected]> CC: Linus Torvalds <[email protected]> CC: Steven Rostedt <[email protected]> CC: Ingo Molnar <[email protected]> CC: Borislav Petkov <[email protected]> CC: "H. Peter Anvin" <[email protected]> CC: Andy Lutomirski <[email protected]> CC: Oleg Nesterov <[email protected]> CC: Frederic Weisbecker <[email protected]> CC: Alexei Starovoitov <[email protected]> CC: Will Drewry <[email protected]> CC: Kees Cook <[email protected]> CC: [email protected] CC: [email protected] --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
