Messages in this thread Patch in this message | | | From | Denys Vlasenko <> | Subject | [PATCH 8/8] x86/asm/entry/64: Reduce padding in execve stubs | Date | Tue, 7 Apr 2015 22:43:44 +0200 |
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execve stubs are 7 bytes only. Padding them to 16 bytes is a waste.
text data bss dec hex filename 12594 0 0 12594 3132 entry_64.o.before 12530 0 0 12530 30f2 entry_64.o
Run-tested.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com> CC: Linus Torvalds <torvalds@linux-foundation.org> CC: Steven Rostedt <rostedt@goodmis.org> CC: Ingo Molnar <mingo@kernel.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/kernel/entry_64.S | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 05224d4..2aa3eca 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -434,8 +434,12 @@ return_from_execve: jmp int_ret_from_sys_call CFI_ENDPROC END(stub_execve) - -ENTRY(stub_execveat) +/* + * Remaining execve stubs are only 7 bytes long. + * ENTRY() often aligns to 16 bytes, which in this case has no benefits. + */ + .align 8 +GLOBAL(stub_execveat) CFI_STARTPROC DEFAULT_FRAME 0, 8 call sys_execveat @@ -444,14 +448,16 @@ ENTRY(stub_execveat) END(stub_execveat) #ifdef CONFIG_X86_X32_ABI -ENTRY(stub_x32_execve) + .align 8 +GLOBAL(stub_x32_execve) CFI_STARTPROC DEFAULT_FRAME 0, 8 call compat_sys_execve jmp return_from_execve CFI_ENDPROC END(stub_x32_execve) -ENTRY(stub_x32_execveat) + .align 8 +GLOBAL(stub_x32_execveat) CFI_STARTPROC DEFAULT_FRAME 0, 8 call compat_sys_execveat @@ -461,13 +467,15 @@ END(stub_x32_execveat) #endif #ifdef CONFIG_IA32_EMULATION -ENTRY(stub32_execve) + .align 8 +GLOBAL(stub32_execve) CFI_STARTPROC call compat_sys_execve jmp return_from_execve CFI_ENDPROC END(stub32_execve) -ENTRY(stub32_execveat) + .align 8 +GLOBAL(stub32_execveat) CFI_STARTPROC call compat_sys_execveat jmp return_from_execve -- 1.8.1.4
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