Add an assembly fast path for the syscall audit entry path on 64bit. Some distros enable auditing by default which forces us through the syscall auditing path even if there are no rules.
I wrote some test cases to validate the patch: http://ozlabs.org/~anton/junkcode/audit_tests.tar.gz And to test the performance I ran a simple null syscall microbenchmark on a POWER7 box: http://ozlabs.org/~anton/junkcode/null_syscall.c Baseline: 949.2 cycles Patched: 920.6 cycles An improvement of 3%. Most of the potential gains are masked by the syscall audit exit path which will be fixed in a subsequent patch. Signed-off-by: Anton Blanchard <an...@samba.org> --- Index: b/arch/powerpc/kernel/entry_64.S =================================================================== --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -34,6 +34,12 @@ #include <asm/ftrace.h> #include <asm/hw_irq.h> +/* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this. */ +#include <linux/elf-em.h> +#define AUDIT_ARCH_PPC (EM_PPC) +#define AUDIT_ARCH_PPC64 (EM_PPC64|__AUDIT_ARCH_64BIT) +#define __AUDIT_ARCH_64BIT 0x80000000 + /* * System calls. */ @@ -244,6 +250,10 @@ syscall_error: /* Traced system call support */ syscall_dotrace: +#ifdef CONFIG_AUDITSYSCALL + andi. r11,r10,(_TIF_SYSCALL_T_OR_A & ~_TIF_SYSCALL_AUDIT) + beq audit_entry +#endif bl .save_nvgprs addi r3,r1,STACK_FRAME_OVERHEAD bl .do_syscall_trace_enter @@ -253,6 +263,7 @@ syscall_dotrace: * for the call number to look up in the table (r0). */ mr r0,r3 +.Laudit_entry_return: ld r3,GPR3(r1) ld r4,GPR4(r1) ld r5,GPR5(r1) @@ -264,6 +275,34 @@ syscall_dotrace: ld r10,TI_FLAGS(r10) b .Lsyscall_dotrace_cont +#ifdef CONFIG_AUDITSYSCALL +audit_entry: + ld r4,GPR0(r1) + ld r5,GPR3(r1) + ld r6,GPR4(r1) + ld r7,GPR5(r1) + ld r8,GPR6(r1) + + andi. r11,r10,_TIF_32BIT + beq 1f + + lis r3,AUDIT_ARCH_PPC@h + ori r3,r3,AUDIT_ARCH_PPC@l + clrldi r5,r5,32 + clrldi r6,r6,32 + clrldi r7,r7,32 + clrldi r8,r8,32 + bl .__audit_syscall_entry + ld r0,GPR0(r1) + b .Laudit_entry_return + +1: lis r3,AUDIT_ARCH_PPC64@h + ori r3,r3,AUDIT_ARCH_PPC64@l + bl .__audit_syscall_entry + ld r0,GPR0(r1) + b .Laudit_entry_return +#endif + syscall_enosys: li r3,-ENOSYS b syscall_exit -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
