Commit 5cbf1565 authored by Roland McGrath's avatar Roland McGrath
Browse files

x86_64 ia32 syscall audit fast-path



This adds fast paths for 32-bit syscall entry and exit when
TIF_SYSCALL_AUDIT is set, but no other kind of syscall tracing.
These paths does not need to save and restore all registers as
the general case of tracing does.  Avoiding the iret return path
when syscall audit is enabled helps performance a lot.
Signed-off-by: default avatarRoland McGrath <roland@redhat.com>
parent 86a1c34a
......@@ -15,6 +15,16 @@
#include <asm/irqflags.h>
#include <linux/linkage.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 int_ret_from_sys_call
#define sysretl_audit int_ret_from_sys_call
#endif
#define IA32_NR_syscalls ((ia32_syscall_end - ia32_sys_call_table)/8)
.macro IA32_ARG_FIXUP noebp=0
......@@ -148,13 +158,15 @@ ENTRY(ia32_sysenter_target)
ja ia32_badsys
sysenter_do_call:
IA32_ARG_FIXUP 1
sysenter_dispatch:
call *ia32_sys_call_table(,%rax,8)
movq %rax,RAX-ARGOFFSET(%rsp)
GET_THREAD_INFO(%r10)
DISABLE_INTERRUPTS(CLBR_NONE)
TRACE_IRQS_OFF
testl $_TIF_ALLWORK_MASK,TI_flags(%r10)
jnz int_ret_from_sys_call
jnz sysexit_audit
sysexit_from_sys_call:
andl $~TS_COMPAT,TI_status(%r10)
/* clear IF, that popfq doesn't enable interrupts early */
andl $~0x200,EFLAGS-R11(%rsp)
......@@ -170,9 +182,63 @@ sysenter_do_call:
TRACE_IRQS_ON
ENABLE_INTERRUPTS_SYSEXIT32
sysenter_tracesys:
#ifdef CONFIG_AUDITSYSCALL
.macro auditsys_entry_common
movl %esi,%r9d /* 6th arg: 4th syscall arg */
movl %edx,%r8d /* 5th arg: 3rd syscall arg */
/* (already in %ecx) 4th arg: 2nd syscall arg */
movl %ebx,%edx /* 3rd arg: 1st syscall arg */
movl %eax,%esi /* 2nd arg: syscall number */
movl $AUDIT_ARCH_I386,%edi /* 1st arg: audit arch */
call audit_syscall_entry
movl RAX-ARGOFFSET(%rsp),%eax /* reload syscall number */
cmpl $(IA32_NR_syscalls-1),%eax
ja ia32_badsys
movl %ebx,%edi /* reload 1st syscall arg */
movl RCX-ARGOFFSET(%rsp),%esi /* reload 2nd syscall arg */
movl RDX-ARGOFFSET(%rsp),%edx /* reload 3rd syscall arg */
movl RSI-ARGOFFSET(%rsp),%ecx /* reload 4th syscall arg */
movl RDI-ARGOFFSET(%rsp),%r8d /* reload 5th syscall arg */
.endm
.macro auditsys_exit exit
testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),TI_flags(%r10)
jnz int_ret_from_sys_call
TRACE_IRQS_ON
sti
movl %eax,%esi /* second arg, syscall return value */
cmpl $0,%eax /* is it < 0? */
setl %al /* 1 if so, 0 if not */
movzbl %al,%edi /* zero-extend that into %edi */
inc %edi /* first arg, 0->1(AUDITSC_SUCCESS), 1->2(AUDITSC_FAILURE) */
call audit_syscall_exit
GET_THREAD_INFO(%r10)
movl RAX-ARGOFFSET(%rsp),%eax /* reload syscall return value */
movl RBP-ARGOFFSET(%rsp),%ebp /* reload user register value */
movl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),%edi
cli
TRACE_IRQS_OFF
testl %edi,TI_flags(%r10)
jnz int_with_check
jmp \exit
.endm
sysenter_auditsys:
CFI_RESTORE_STATE
auditsys_entry_common
movl %ebp,%r9d /* reload 6th syscall arg */
jmp sysenter_dispatch
sysexit_audit:
auditsys_exit sysexit_from_sys_call
#endif
sysenter_tracesys:
xchgl %r9d,%ebp
#ifdef CONFIG_AUDITSYSCALL
testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags(%r10)
jz sysenter_auditsys
#endif
SAVE_REST
CLEAR_RREGS
movq %r9,R9(%rsp)
......@@ -252,13 +318,15 @@ cstar_do_call:
cmpl $IA32_NR_syscalls-1,%eax
ja ia32_badsys
IA32_ARG_FIXUP 1
cstar_dispatch:
call *ia32_sys_call_table(,%rax,8)
movq %rax,RAX-ARGOFFSET(%rsp)
GET_THREAD_INFO(%r10)
DISABLE_INTERRUPTS(CLBR_NONE)
TRACE_IRQS_OFF
testl $_TIF_ALLWORK_MASK,TI_flags(%r10)
jnz int_ret_from_sys_call
jnz sysretl_audit
sysretl_from_sys_call:
andl $~TS_COMPAT,TI_status(%r10)
RESTORE_ARGS 1,-ARG_SKIP,1,1,1
movl RIP-ARGOFFSET(%rsp),%ecx
......@@ -270,8 +338,23 @@ cstar_do_call:
CFI_RESTORE rsp
USERGS_SYSRET32
cstar_tracesys:
#ifdef CONFIG_AUDITSYSCALL
cstar_auditsys:
CFI_RESTORE_STATE
movl %r9d,R9-ARGOFFSET(%rsp) /* register to be clobbered by call */
auditsys_entry_common
movl R9-ARGOFFSET(%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),TI_flags(%r10)
jz cstar_auditsys
#endif
xchgl %r9d,%ebp
SAVE_REST
CLEAR_RREGS
......
......@@ -492,6 +492,7 @@ tracesys:
* Has correct top of stack, but partial stack frame.
*/
.globl int_ret_from_sys_call
.globl int_with_check
int_ret_from_sys_call:
DISABLE_INTERRUPTS(CLBR_NONE)
TRACE_IRQS_OFF
......
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