2 files changed, 50 insertions, 1 deletions

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index a169225869cc..db7d34a89d2e 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -53,6 +53,12 @@
 #include <asm/paravirt.h>
 #include <asm/ftrace.h>
 
+/* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this.  */
+#include <linux/elf-em.h>
+#define AUDIT_ARCH_X86_64       (EM_X86_64|__AUDIT_ARCH_64BIT|__AUDIT_ARCH_LE)
+#define __AUDIT_ARCH_64BIT 0x80000000
+#define __AUDIT_ARCH_LE    0x40000000
+
         .code64
 
 #ifdef CONFIG_FTRACE
@@ -351,6 +357,7 @@ ENTRY(system_call_after_swapgs)
         GET_THREAD_INFO(%rcx)
         testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%rcx)
         jnz tracesys
+system_call_fastpath:
         cmpq $__NR_syscall_max,%rax
         ja badsys
         movq %r10,%rcx
@@ -402,6 +409,10 @@ sysret_careful:
 sysret_signal:
         TRACE_IRQS_ON
         ENABLE_INTERRUPTS(CLBR_NONE)
+#ifdef CONFIG_AUDITSYSCALL
+        bt $TIF_SYSCALL_AUDIT,%edx
+        jc sysret_audit
+#endif
         /* edx: work flags (arg3) */
         leaq do_notify_resume(%rip),%rax
         leaq -ARGOFFSET(%rsp),%rdi # &pt_regs -> arg1
@@ -418,8 +429,45 @@ badsys:
         movq $-ENOSYS,RAX-ARGOFFSET(%rsp)
         jmp ret_from_sys_call
 
+#ifdef CONFIG_AUDITSYSCALL
+        /*
+         * Fast path for syscall audit without full syscall trace.
+         * We just call audit_syscall_entry() directly, and then
+         * jump back to the normal fast path.
+         */
+auditsys:
+        movq %r10,%r9                   /* 6th arg: 4th syscall arg */
+        movq %rdx,%r8                   /* 5th arg: 3rd syscall arg */
+        movq %rsi,%rcx                  /* 4th arg: 2nd syscall arg */
+        movq %rdi,%rdx                  /* 3rd arg: 1st syscall arg */
+        movq %rax,%rsi                  /* 2nd arg: syscall number */
+        movl $AUDIT_ARCH_X86_64,%edi    /* 1st arg: audit arch */
+        call audit_syscall_entry
+        LOAD_ARGS 0             /* reload call-clobbered registers */
+        jmp system_call_fastpath
+
+        /*
+         * Return fast path for syscall audit.  Call audit_syscall_exit()
+         * directly and then jump back to the fast path with TIF_SYSCALL_AUDIT
+         * masked off.
+         */
+sysret_audit:
+        movq %rax,%rsi          /* second arg, syscall return value */
+        cmpq $0,%rax            /* 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
+        movl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),%edi
+        jmp sysret_check
+#endif  /* CONFIG_AUDITSYSCALL */
+
         /* Do syscall tracing */
 tracesys:                        
+#ifdef CONFIG_AUDITSYSCALL
+        testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags(%rcx)
+        jz auditsys
+#endif
         SAVE_REST
         movq $-ENOSYS,RAX(%rsp) /* ptrace can change this for a bad syscall */
         FIXUP_TOP_OF_STACK %rdi
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index c10e7aae04d7..4699950e65bd 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1476,7 +1476,8 @@ void audit_syscall_entry(int arch, int major,
         struct audit_context *context = tsk->audit_context;
         enum audit_state     state;
 
-        BUG_ON(!context);
+        if (unlikely(!context))
+                return;
 
         /*
          * This happens only on certain architectures that make system