Re: [PATCH] i386/audit: stop scribbling on the stack frame

On Sun, 26 Oct 2014, Richard Guy Briggs wrote: > diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S > index b553ed8..344b63f 100644 > --- a/arch/x86/kernel/entry_32.S > +++ b/arch/x86/kernel/entry_32.S > @@ -447,15 +447,14 @@ sysenter_exit: > sysenter_audit: > testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags(%ebp) > jnz syscall_trace_entry > - addl $4,%esp > - CFI_ADJUST_CFA_OFFSET -4 > - movl %esi,4(%esp) /* 5th arg: 4th syscall arg */ > - movl %edx,(%esp) /* 4th arg: 3rd syscall arg */ > - /* %ecx already in %ecx 3rd arg: 2nd syscall arg */ > - movl %ebx,%edx /* 2nd arg: 1st syscall arg */ > - /* %eax already in %eax 1st arg: syscall number */ > + /* movl PT_ECX(%esp), %ecx already set, a1: 3nd arg to audit */ > + /* movl PT_EAX(%esp), %eax already set, syscall number: 1st arg to audit */ > + pushl_cfi %esi /* a3: 5th arg */ > + pushl_cfi %edx /* a2: 4th arg */ > + movl %ebx, %edx /* ebx/a0: 2nd arg to audit */ > call __audit_syscall_entry > - pushl_cfi %ebx > + popl_cfi %ecx /* get that remapped edx off the stack */ > + popl_cfi %ecx /* get that remapped esi off the stack */ Why use pop instead of simply adjusting esp and CFI by 8?