x86_64: fix ia32 AMD syscall audit fast-path

The new code in commit 5cbf1565f29eb57a86a305b08836613508e294d7
has a bug in the version supporting the AMD 'syscall' instruction.
It clobbers the user's %ecx register value (with the %ebp value).

This change fixes it.

Signed-off-by: Roland McGrath <roland@redhat.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S
index e4bd1793a5e4..ffc1bb4fed7d 100644
--- a/arch/x86/ia32/ia32entry.S
+++ b/arch/x86/ia32/ia32entry.S
@@ -201,7 +201,7 @@ sysexit_from_sys_call:
         movl RDI-ARGOFFSET(%rsp),%r8d   /* reload 5th syscall arg */
         .endm
 
-        .macro auditsys_exit exit
+        .macro auditsys_exit exit,ebpsave=RBP
         testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),TI_flags(%r10)
         jnz int_ret_from_sys_call
         TRACE_IRQS_ON
@@ -214,7 +214,7 @@ sysexit_from_sys_call:
         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 \ebpsave-ARGOFFSET(%rsp),%ebp /* reload user register value */
         movl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),%edi
         cli
         TRACE_IRQS_OFF
@@ -347,7 +347,7 @@ cstar_auditsys:
         jmp cstar_dispatch
 
 sysretl_audit:
-        auditsys_exit sysretl_from_sys_call
+        auditsys_exit sysretl_from_sys_call, RCX /* user %ebp in RCX slot */
 #endif
 
 cstar_tracesys: