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[PATCH] x86: compress the stack layout of do_page_fault()

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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>
This commit is contained in:
Ingo Molnar 2005-09-03 15:56:26 -07:00 committed by Linus Torvalds
parent 7e06066b87
commit 869f96a00e
1 changed files with 17 additions and 14 deletions
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31
arch/i386/mm/fault.c
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@ -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: