Use of a small macro - one with conditional expansion - does more harm than good. It obfuscates code, with minimal code reuse.
For example, because of obfuscation it's not obvious that in ia32_sysenter_target, we can optimize loading of r9 - currently it is loaded with a detour through ebp. This patch folds IA32_ARG_FIXUP macro into its callers. No code changes. Signed-off-by: Denys Vlasenko <[email protected]> CC: Linus Torvalds <[email protected]> CC: Oleg Nesterov <[email protected]> CC: Borislav Petkov <[email protected]> CC: "H. Peter Anvin" <[email protected]> CC: Andy Lutomirski <[email protected]> CC: Frederic Weisbecker <[email protected]> CC: X86 ML <[email protected]> CC: Alexei Starovoitov <[email protected]> CC: Will Drewry <[email protected]> CC: Kees Cook <[email protected]> CC: [email protected] --- arch/x86/ia32/ia32entry.S | 32 ++++++++++++++++++-------------- 1 file changed, 18 insertions(+), 14 deletions(-) diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S index b567056..6dcd372 100644 --- a/arch/x86/ia32/ia32entry.S +++ b/arch/x86/ia32/ia32entry.S @@ -30,17 +30,6 @@ .section .entry.text, "ax" - .macro IA32_ARG_FIXUP noebp=0 - movl %edi,%r8d - .if \noebp - .else - movl %ebp,%r9d - .endif - xchg %ecx,%esi - movl %ebx,%edi - movl %edx,%edx /* zero extension */ - .endm - /* clobbers %rax */ .macro CLEAR_RREGS _r9=rax xorl %eax,%eax @@ -178,7 +167,12 @@ sysenter_flags_fixed: cmpq $(IA32_NR_syscalls-1),%rax ja ia32_badsys sysenter_do_call: - IA32_ARG_FIXUP + /* 32bit syscall -> 64bit C ABI argument conversion */ + movl %edi,%r8d /* arg5 */ + movl %ebp,%r9d /* arg6 */ + xchg %ecx,%esi /* rsi:arg2, rcx:arg4 */ + movl %ebx,%edi /* arg1 */ + movl %edx,%edx /* arg3 (zero extension) */ sysenter_dispatch: call *ia32_sys_call_table(,%rax,8) movq %rax,RAX(%rsp) @@ -360,7 +354,12 @@ ENTRY(ia32_cstar_target) cmpq $IA32_NR_syscalls-1,%rax ja ia32_badsys cstar_do_call: - IA32_ARG_FIXUP 1 + /* 32bit syscall -> 64bit C ABI argument conversion */ + movl %edi,%r8d /* arg5 */ + /* r9 already loaded */ /* arg6 */ + xchg %ecx,%esi /* rsi:arg2, rcx:arg4 */ + movl %ebx,%edi /* arg1 */ + movl %edx,%edx /* arg3 (zero extension) */ cstar_dispatch: call *ia32_sys_call_table(,%rax,8) movq %rax,RAX(%rsp) @@ -477,7 +476,12 @@ ENTRY(ia32_syscall) cmpq $(IA32_NR_syscalls-1),%rax ja ia32_badsys ia32_do_call: - IA32_ARG_FIXUP + /* 32bit syscall -> 64bit C ABI argument conversion */ + movl %edi,%r8d /* arg5 */ + movl %ebp,%r9d /* arg6 */ + xchg %ecx,%esi /* rsi:arg2, rcx:arg4 */ + movl %ebx,%edi /* arg1 */ + movl %edx,%edx /* arg3 (zero extension) */ call *ia32_sys_call_table(,%rax,8) # xxx: rip relative ia32_sysret: movq %rax,RAX(%rsp) -- 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/
