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authorIngo Molnar <mingo@elte.hu>2005-09-03 15:56:26 -0700
committerLinus Torvalds <torvalds@evo.osdl.org>2005-09-05 00:06:09 -0700
commit869f96a00e8f53c7db8470ca9cf72e2e3fa40119 (patch)
treee28e526eb0e9d304d79dab3a20c944959a6ee38e
parent7e06066b87ffd2c7a7f4c3f1c612293307270976 (diff)
downloadop-kernel-dev-869f96a00e8f53c7db8470ca9cf72e2e3fa40119.zip
op-kernel-dev-869f96a00e8f53c7db8470ca9cf72e2e3fa40119.tar.gz
[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>
-rw-r--r--arch/i386/mm/fault.c31
1 files changed, 17 insertions, 14 deletions
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 @@ static inline int is_prefetch(struct pt_regs *regs, unsigned long addr,
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 @@ fastcall void do_page_fault(struct pt_regs *regs, unsigned long error_code)
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 @@ fastcall void do_page_fault(struct pt_regs *regs, unsigned long error_code)
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 @@ fastcall void do_page_fault(struct pt_regs *regs, unsigned long error_code)
* 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 @@ bad_area_nosemaphore:
/* 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 @@ do_sigbus:
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:
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