From: Franck Bui-Huu Date: Fri, 18 Aug 2006 14:18:09 +0000 (+0200) Subject: [MIPS] get_wchan(): remove uses of mfinfo[64] X-Git-Tag: v2.6.19-rc1~1011 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b5943182592ba256639a569c7d5305cf60360733;p=linux-2.6 [MIPS] get_wchan(): remove uses of mfinfo[64] This array was used to 'cache' some frame info about scheduler functions to speed up get_wchan(). This array was 1Ko size and was only used when CONFIG_KALLSYMS was set but declared for all configs. Rather than make the array statement conditional, this patches removes this array and its uses. Indeed the common case doesn't seem to use this array and get_wchan() is not a critical path anyways. It results in a smaller bss and a smaller/cleaner code: text data bss dec hex filename 2543808 254148 139296 2937252 2cd1a4 vmlinux-new-get-wchan 2544080 254148 143392 2941620 2ce2b4 vmlinux~old Signed-off-by: Franck Bui-Huu Signed-off-by: Ralf Baechle --- diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c index b160ea30de..2613a0dd4b 100644 --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -273,13 +273,15 @@ long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL); } -static struct mips_frame_info { - void *func; - unsigned long func_size; - int frame_size; - int pc_offset; -} *schedule_frame, mfinfo[64]; -static int mfinfo_num; +/* + * + */ +struct mips_frame_info { + void *func; + unsigned long func_size; + int frame_size; + int pc_offset; +}; static inline int is_ra_save_ins(union mips_instruction *ip) { @@ -348,45 +350,30 @@ err: return -1; } +static struct mips_frame_info schedule_mfi __read_mostly; + static int __init frame_info_init(void) { - int i; + unsigned long size = 0; #ifdef CONFIG_KALLSYMS + unsigned long ofs; char *modname; char namebuf[KSYM_NAME_LEN + 1]; - unsigned long start, size, ofs; - extern char __sched_text_start[], __sched_text_end[]; - extern char __lock_text_start[], __lock_text_end[]; - - start = (unsigned long)__sched_text_start; - for (i = 0; i < ARRAY_SIZE(mfinfo); i++) { - if (start == (unsigned long)schedule) - schedule_frame = &mfinfo[i]; - if (!kallsyms_lookup(start, &size, &ofs, &modname, namebuf)) - break; - mfinfo[i].func = (void *)(start + ofs); - mfinfo[i].func_size = size; - start += size - ofs; - if (start >= (unsigned long)__lock_text_end) - break; - if (start == (unsigned long)__sched_text_end) - start = (unsigned long)__lock_text_start; - } -#else - mfinfo[0].func = schedule; - schedule_frame = &mfinfo[0]; + + kallsyms_lookup((unsigned long)schedule, &size, &ofs, &modname, namebuf); #endif - for (i = 0; i < ARRAY_SIZE(mfinfo) && mfinfo[i].func; i++) - get_frame_info(mfinfo + i); + schedule_mfi.func = schedule; + schedule_mfi.func_size = size; + + get_frame_info(&schedule_mfi); /* * Without schedule() frame info, result given by * thread_saved_pc() and get_wchan() are not reliable. */ - if (schedule_frame->pc_offset < 0) + if (schedule_mfi.pc_offset < 0) printk("Can't analyze schedule() prologue at %p\n", schedule); - mfinfo_num = i; return 0; } @@ -402,58 +389,11 @@ unsigned long thread_saved_pc(struct task_struct *tsk) /* New born processes are a special case */ if (t->reg31 == (unsigned long) ret_from_fork) return t->reg31; - - if (!schedule_frame || schedule_frame->pc_offset < 0) + if (schedule_mfi.pc_offset < 0) return 0; - return ((unsigned long *)t->reg29)[schedule_frame->pc_offset]; + return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset]; } -/* get_wchan - a maintenance nightmare^W^Wpain in the ass ... */ -unsigned long get_wchan(struct task_struct *p) -{ - unsigned long stack_page; - unsigned long pc; -#ifdef CONFIG_KALLSYMS - unsigned long frame; -#endif - - if (!p || p == current || p->state == TASK_RUNNING) - return 0; - - stack_page = (unsigned long)task_stack_page(p); - if (!stack_page || !mfinfo_num) - return 0; - - pc = thread_saved_pc(p); -#ifdef CONFIG_KALLSYMS - if (!in_sched_functions(pc)) - return pc; - - frame = p->thread.reg29 + schedule_frame->frame_size; - do { - int i; - - if (frame < stack_page || frame > stack_page + THREAD_SIZE - 32) - return 0; - - for (i = mfinfo_num - 1; i >= 0; i--) { - if (pc >= (unsigned long) mfinfo[i].func) - break; - } - if (i < 0) - break; - - if (mfinfo[i].pc_offset < 0) - break; - pc = ((unsigned long *)frame)[mfinfo[i].pc_offset]; - if (!mfinfo[i].frame_size) - break; - frame += mfinfo[i].frame_size; - } while (in_sched_functions(pc)); -#endif - - return pc; -} #ifdef CONFIG_KALLSYMS /* used by show_backtrace() */ @@ -504,3 +444,31 @@ unsigned long unwind_stack(struct task_struct *task, unsigned long *sp, return __kernel_text_address(pc) ? pc : 0; } #endif + +/* + * get_wchan - a maintenance nightmare^W^Wpain in the ass ... + */ +unsigned long get_wchan(struct task_struct *task) +{ + unsigned long pc = 0; +#ifdef CONFIG_KALLSYMS + unsigned long sp; +#endif + + if (!task || task == current || task->state == TASK_RUNNING) + goto out; + if (!task_stack_page(task)) + goto out; + + pc = thread_saved_pc(task); + +#ifdef CONFIG_KALLSYMS + sp = task->thread.reg29 + schedule_mfi.frame_size; + + while (in_sched_functions(pc)) + pc = unwind_stack(task, &sp, pc, 0); +#endif + +out: + return pc; +}