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Date: Wed, 5 Aug 2015 13:15:12 -0700 From: tip-bot for Andy Lutomirski <tipbot@...or.com> To: linux-tip-commits@...r.kernel.org Cc: hpa@...or.com, luto@...nel.org, tglx@...utronix.de, mingo@...nel.org, brgerst@...il.com, bp@...en8.de, peterz@...radead.org, oleg@...hat.com, linux-kernel@...r.kernel.org, dvlasenk@...hat.com, eparis@...isplace.org, torvalds@...ux-foundation.org Subject: [tip:x86/asm] x86/entry/32: Remove 32-bit syscall audit optimizations Commit-ID: c5f69fde26d1581ee495f68bb9de4049c8168a04 Gitweb: http://git.kernel.org/tip/c5f69fde26d1581ee495f68bb9de4049c8168a04 Author: Andy Lutomirski <luto@...nel.org> AuthorDate: Fri, 31 Jul 2015 14:41:08 -0700 Committer: Ingo Molnar <mingo@...nel.org> CommitDate: Wed, 5 Aug 2015 10:54:35 +0200 x86/entry/32: Remove 32-bit syscall audit optimizations The asm audit optimizations are ugly and obfuscate the code too much. Remove them. This will regress performance if syscall auditing is enabled on 32-bit kernels and SYSENTER is in use. If this becomes a problem, interested parties are encouraged to implement the equivalent of the 64-bit opportunistic SYSRET optimization. Alternatively, a case could be made that, on 32-bit kernels, a less messy asm audit optimization could be done. 32-bit kernels don't have the complicated partial register saving tricks that 64-bit kernels have, so the SYSENTER post-syscall path could just call the audit hooks directly. Any reimplementation of this ought to demonstrate that it only calls the audit hook once per syscall, though, which does not currently appear to be true. Someone would have to make the case that doing so would be better than implementing opportunistic SYSEXIT, though. Signed-off-by: Andy Lutomirski <luto@...nel.org> Cc: Borislav Petkov <bp@...en8.de> Cc: Brian Gerst <brgerst@...il.com> Cc: Denys Vlasenko <dvlasenk@...hat.com> Cc: Eric Paris <eparis@...isplace.org> Cc: Linus Torvalds <torvalds@...ux-foundation.org> Cc: Oleg Nesterov <oleg@...hat.com> Cc: Peter Zijlstra <peterz@...radead.org> Cc: Thomas Gleixner <tglx@...utronix.de> Link: http://lkml.kernel.org/r/212be39dd8c90b44c4b7bbc678128d6b88bdb9912.1438378274.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@...nel.org> --- arch/x86/entry/entry_32.S | 48 ++--------------------------------------------- 1 file changed, 2 insertions(+), 46 deletions(-) diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index f940e24..a3c307a 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -45,16 +45,6 @@ #include <asm/asm.h> #include <asm/smap.h> -/* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this. */ -#include <linux/elf-em.h> -#define AUDIT_ARCH_I386 (EM_386|__AUDIT_ARCH_LE) -#define __AUDIT_ARCH_LE 0x40000000 - -#ifndef CONFIG_AUDITSYSCALL -# define sysenter_audit syscall_trace_entry -# define sysexit_audit syscall_exit_work -#endif - .section .entry.text, "ax" /* @@ -339,7 +329,7 @@ sysenter_past_esp: GET_THREAD_INFO(%ebp) testl $_TIF_WORK_SYSCALL_ENTRY, TI_flags(%ebp) - jnz sysenter_audit + jnz syscall_trace_entry sysenter_do_call: cmpl $(NR_syscalls), %eax jae sysenter_badsys @@ -351,7 +341,7 @@ sysenter_after_call: TRACE_IRQS_OFF movl TI_flags(%ebp), %ecx testl $_TIF_ALLWORK_MASK, %ecx - jnz sysexit_audit + jnz syscall_exit_work sysenter_exit: /* if something modifies registers it must also disable sysexit */ movl PT_EIP(%esp), %edx @@ -362,40 +352,6 @@ sysenter_exit: PTGS_TO_GS ENABLE_INTERRUPTS_SYSEXIT -#ifdef CONFIG_AUDITSYSCALL -sysenter_audit: - testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT), TI_flags(%ebp) - jnz syscall_trace_entry - /* movl PT_EAX(%esp), %eax already set, syscall number: 1st arg to audit */ - movl PT_EBX(%esp), %edx /* ebx/a0: 2nd arg to audit */ - /* movl PT_ECX(%esp), %ecx already set, a1: 3nd arg to audit */ - pushl PT_ESI(%esp) /* a3: 5th arg */ - pushl PT_EDX+4(%esp) /* a2: 4th arg */ - call __audit_syscall_entry - popl %ecx /* get that remapped edx off the stack */ - popl %ecx /* get that remapped esi off the stack */ - movl PT_EAX(%esp), %eax /* reload syscall number */ - jmp sysenter_do_call - -sysexit_audit: - testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), %ecx - jnz syscall_exit_work - TRACE_IRQS_ON - ENABLE_INTERRUPTS(CLBR_ANY) - movl %eax, %edx /* second arg, syscall return value */ - cmpl $-MAX_ERRNO, %eax /* is it an error ? */ - setbe %al /* 1 if so, 0 if not */ - movzbl %al, %eax /* zero-extend that */ - call __audit_syscall_exit - DISABLE_INTERRUPTS(CLBR_ANY) - TRACE_IRQS_OFF - movl TI_flags(%ebp), %ecx - testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), %ecx - jnz syscall_exit_work - movl PT_EAX(%esp), %eax /* reload syscall return value */ - jmp sysenter_exit -#endif - .pushsection .fixup, "ax" 2: movl $0, PT_FS(%esp) jmp 1b -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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