Re: [PATCH 3/4] powerpc: Optimise 64bit syscall auditing entry path

From: Eric Paris
Date: Wed Apr 10 2013 - 12:56:58 EST


Patches 1 and 2 I applied for 3.10, but I'd really like to have someone who knows PPC ack 3 and 4. Especially if there is a hope that it goes through my tree...

Link to original messages for your ease of review...

http://marc.info/?l=linux-kernel&m=135768892320439&w=2
http://marc.info/?l=linux-kernel&m=135768895320472&w=2

-Eric

----- Original Message -----
>
> 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 <anton@xxxxxxxxx>
> ---
>
> 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 majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/