[PATCH] x86: compress the stack layout of do_page_fault()
This patch pushes the creation of a rare signal frame (SIGBUS or SIGSEGV)
into a separate function, thus saving stackspace in the main
do_page_fault() stackframe. The effect is 132 bytes less of stack used by
the typical do_page_fault() invocation - resulting in a denser
cache-layout.
(Another minor effect is that in case of kernel crashes that come from a
pagefault, we add less space to the already existing frame, giving the
crash functions a slightly higher chance to do their stuff without
overflowing the stack.)
(The changes also result in slightly cleaner code.)
argument bugfix from "Guillaume C." <guichaz@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/i386/mm/fault.c b/arch/i386/mm/fault.c
index 8e90339..61d9e34 100644
--- a/arch/i386/mm/fault.c
+++ b/arch/i386/mm/fault.c
@@ -199,6 +199,18 @@
return 0;
}
+static noinline void force_sig_info_fault(int si_signo, int si_code,
+ unsigned long address, struct task_struct *tsk)
+{
+ siginfo_t info;
+
+ info.si_signo = si_signo;
+ info.si_errno = 0;
+ info.si_code = si_code;
+ info.si_addr = (void __user *)address;
+ force_sig_info(si_signo, &info, tsk);
+}
+
fastcall void do_invalid_op(struct pt_regs *, unsigned long);
/*
@@ -218,8 +230,7 @@
struct vm_area_struct * vma;
unsigned long address;
unsigned long page;
- int write;
- siginfo_t info;
+ int write, si_code;
/* get the address */
__asm__("movl %%cr2,%0":"=r" (address));
@@ -233,7 +244,7 @@
tsk = current;
- info.si_code = SEGV_MAPERR;
+ si_code = SEGV_MAPERR;
/*
* We fault-in kernel-space virtual memory on-demand. The
@@ -313,7 +324,7 @@
* we can handle it..
*/
good_area:
- info.si_code = SEGV_ACCERR;
+ si_code = SEGV_ACCERR;
write = 0;
switch (error_code & 3) {
default: /* 3: write, present */
@@ -387,11 +398,7 @@
/* Kernel addresses are always protection faults */
tsk->thread.error_code = error_code | (address >= TASK_SIZE);
tsk->thread.trap_no = 14;
- info.si_signo = SIGSEGV;
- info.si_errno = 0;
- /* info.si_code has been set above */
- info.si_addr = (void __user *)address;
- force_sig_info(SIGSEGV, &info, tsk);
+ force_sig_info_fault(SIGSEGV, si_code, address, tsk);
return;
}
@@ -500,11 +507,7 @@
tsk->thread.cr2 = address;
tsk->thread.error_code = error_code;
tsk->thread.trap_no = 14;
- info.si_signo = SIGBUS;
- info.si_errno = 0;
- info.si_code = BUS_ADRERR;
- info.si_addr = (void __user *)address;
- force_sig_info(SIGBUS, &info, tsk);
+ force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk);
return;
vmalloc_fault: