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Commit c5f638ac authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Ingo Molnar
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x86/entry/64/compat: Remove audit optimizations 



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: default avatarAndy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/0bcca79ac7ff835d0e5a38725298865b01347a82.1444091584.git.luto@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent e62a254a

arch/x86/entry/entry_64_compat.S

+2 −96
Original line number Diff line number Diff line
@@ -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 */