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Subject[RFC 13/30] x86/entry/64/compat: Remove audit optimizations
Date
These audit optimizations are messy and hard to maintain.  We'll
get a similar effect from opportunistic sysret when fast compat
system calls are re-implemented.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
arch/x86/entry/entry_64_compat.S | 98 +---------------------------------------
1 file changed, 2 insertions(+), 96 deletions(-)

diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index e11aa38696fe..8f847722ce72 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -16,16 +16,6 @@
#include <linux/linkage.h>
#include <linux/err.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 sysexit_audit ia32_ret_from_sys_call_irqs_off
-# define sysretl_audit ia32_ret_from_sys_call_irqs_off
-#endif
-
.section .entry.text, "ax"

#ifdef CONFIG_PARAVIRT
@@ -148,7 +138,7 @@ sysenter_dispatch:
DISABLE_INTERRUPTS(CLBR_NONE)
TRACE_IRQS_OFF
testl $_TIF_ALLWORK_MASK, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS)
- jnz sysexit_audit
+ jnz ia32_ret_from_sys_call_irqs_off
sysexit_from_sys_call:
/*
* NB: SYSEXIT is not obviously safe for 64-bit kernels -- an
@@ -200,81 +190,12 @@ sysexit_from_sys_call:
*/
USERGS_SYSRET32

-#ifdef CONFIG_AUDITSYSCALL
- .macro auditsys_entry_common
- /*
- * At this point, registers hold syscall args in the 32-bit syscall ABI:
- * EAX is syscall number, the 6 args are in EBX,ECX,EDX,ESI,EDI,EBP.
- *
- * We want to pass them to __audit_syscall_entry(), which is a 64-bit
- * C function with 5 parameters, so shuffle them to match what
- * the function expects: RDI,RSI,RDX,RCX,R8.
- */
- movl %esi, %r8d /* arg5 (R8 ) <= 4th syscall arg (ESI) */
- xchg %ecx, %edx /* arg4 (RCX) <= 3rd syscall arg (EDX) */
- /* arg3 (RDX) <= 2nd syscall arg (ECX) */
- movl %ebx, %esi /* arg2 (RSI) <= 1st syscall arg (EBX) */
- movl %eax, %edi /* arg1 (RDI) <= syscall number (EAX) */
- call __audit_syscall_entry
-
- /*
- * We are going to jump back to the syscall dispatch code.
- * Prepare syscall args as required by the 64-bit C ABI.
- * Registers clobbered by __audit_syscall_entry() are
- * loaded from pt_regs on stack:
- */
- movl ORIG_RAX(%rsp), %eax /* syscall number */
- movl %ebx, %edi /* arg1 */
- movl RCX(%rsp), %esi /* arg2 */
- movl RDX(%rsp), %edx /* arg3 */
- movl RSI(%rsp), %ecx /* arg4 */
- movl RDI(%rsp), %r8d /* arg5 */
- .endm
-
- .macro auditsys_exit exit
- TRACE_IRQS_ON
- ENABLE_INTERRUPTS(CLBR_NONE)
- testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS)
- jnz ia32_ret_from_sys_call
- movl %eax, %esi /* second arg, syscall return value */
- cmpl $-MAX_ERRNO, %eax /* is it an error ? */
- jbe 1f
- movslq %eax, %rsi /* if error sign extend to 64 bits */
-1: setbe %al /* 1 if error, 0 if not */
- movzbl %al, %edi /* zero-extend that into %edi */
- call __audit_syscall_exit
- movl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), %edi
- DISABLE_INTERRUPTS(CLBR_NONE)
- TRACE_IRQS_OFF
- testl %edi, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS)
- jz \exit
- xorl %eax, %eax /* Do not leak kernel information */
- movq %rax, R11(%rsp)
- movq %rax, R10(%rsp)
- movq %rax, R9(%rsp)
- movq %rax, R8(%rsp)
- jmp int_ret_from_sys_call_irqs_off
- .endm
-
-sysenter_auditsys:
- auditsys_entry_common
- movl %ebp, %r9d /* reload 6th syscall arg */
- jmp sysenter_dispatch
-
-sysexit_audit:
- auditsys_exit sysexit_from_sys_call
-#endif
-
sysenter_fix_flags:
pushq $X86_EFLAGS_FIXED
popfq
jmp sysenter_flags_fixed

sysenter_tracesys:
-#ifdef CONFIG_AUDITSYSCALL
- testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT), ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS)
- jz sysenter_auditsys
-#endif
SAVE_EXTRA_REGS
xorl %eax, %eax /* Do not leak kernel information */
movq %rax, R11(%rsp)
@@ -389,7 +310,7 @@ cstar_dispatch:
DISABLE_INTERRUPTS(CLBR_NONE)
TRACE_IRQS_OFF
testl $_TIF_ALLWORK_MASK, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS)
- jnz sysretl_audit
+ jnz ia32_ret_from_sys_call_irqs_off

sysretl_from_sys_call:
andl $~TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS)
@@ -420,22 +341,7 @@ sysretl_from_sys_call:
*/
USERGS_SYSRET32

-#ifdef CONFIG_AUDITSYSCALL
-cstar_auditsys:
- movl %r9d, R9(%rsp) /* register to be clobbered by call */
- auditsys_entry_common
- movl R9(%rsp), %r9d /* reload 6th syscall arg */
- jmp cstar_dispatch
-
-sysretl_audit:
- auditsys_exit sysretl_from_sys_call
-#endif
-
cstar_tracesys:
-#ifdef CONFIG_AUDITSYSCALL
- testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT), ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS)
- jz cstar_auditsys
-#endif
xchgl %r9d, %ebp
SAVE_EXTRA_REGS
xorl %eax, %eax /* Do not leak kernel information */
--
2.4.3


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