From: Ingo Molnar 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." Signed-off-by: Ingo Molnar Signed-off-by: Andrew Morton --- arch/i386/mm/fault.c | 31 +++++++++++++++++-------------- 1 files changed, 17 insertions(+), 14 deletions(-) diff -puN arch/i386/mm/fault.c~x86-compress-the-stack-layout-of-do_page_fault arch/i386/mm/fault.c --- 25/arch/i386/mm/fault.c~x86-compress-the-stack-layout-of-do_page_fault Mon Jul 11 15:19:06 2005 +++ 25-akpm/arch/i386/mm/fault.c Mon Jul 11 15:19:06 2005 @@ -199,6 +199,18 @@ static inline int is_prefetch(struct pt_ return 0; } +static 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_re 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_re 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_re * 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: _