From aa283f49276e7d840a40fb01eee6de97eaa7e012 Mon Sep 17 00:00:00 2001 From: Suresh Siddha Date: Mon, 10 Mar 2008 15:28:05 -0700 Subject: [PATCH] x86, fpu: lazy allocation of FPU area - v5 Only allocate the FPU area when the application actually uses FPU, i.e., in the first lazy FPU trap. This could save memory for non-fpu using apps. for example: on my system after boot, there are around 300 processes, with only 17 using FPU. Signed-off-by: Suresh Siddha Cc: Arjan van de Ven Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- arch/x86/kernel/i387.c | 38 ++++++++++++++++++++++++++++-------- arch/x86/kernel/process.c | 28 +++++++++++++++++--------- arch/x86/kernel/process_32.c | 4 ++++ arch/x86/kernel/process_64.c | 4 ++++ arch/x86/kernel/traps_32.c | 17 ++++++++++++++-- arch/x86/kernel/traps_64.c | 19 +++++++++++++++--- include/asm-x86/i387.h | 2 +- include/asm-x86/processor.h | 2 ++ 8 files changed, 91 insertions(+), 23 deletions(-) diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c index baf632b221..db6839b531 100644 --- a/arch/x86/kernel/i387.c +++ b/arch/x86/kernel/i387.c @@ -8,7 +8,6 @@ #include #include #include -#include #include #include @@ -63,7 +62,6 @@ void __init init_thread_xstate(void) else xstate_size = sizeof(struct i387_fsave_struct); #endif - init_task.thread.xstate = alloc_bootmem(xstate_size); } #ifdef CONFIG_X86_64 @@ -93,12 +91,22 @@ void __cpuinit fpu_init(void) * value at reset if we support XMM instructions and then * remeber the current task has used the FPU. */ -void init_fpu(struct task_struct *tsk) +int init_fpu(struct task_struct *tsk) { if (tsk_used_math(tsk)) { if (tsk == current) unlazy_fpu(tsk); - return; + return 0; + } + + /* + * Memory allocation at the first usage of the FPU and other state. + */ + if (!tsk->thread.xstate) { + tsk->thread.xstate = kmem_cache_alloc(task_xstate_cachep, + GFP_KERNEL); + if (!tsk->thread.xstate) + return -ENOMEM; } if (cpu_has_fxsr) { @@ -120,6 +128,7 @@ void init_fpu(struct task_struct *tsk) * Only the device not available exception or ptrace can call init_fpu. */ set_stopped_child_used_math(tsk); + return 0; } int fpregs_active(struct task_struct *target, const struct user_regset *regset) @@ -136,10 +145,14 @@ int xfpregs_get(struct task_struct *target, const struct user_regset *regset, unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf) { + int ret; + if (!cpu_has_fxsr) return -ENODEV; - init_fpu(target); + ret = init_fpu(target); + if (ret) + return ret; return user_regset_copyout(&pos, &count, &kbuf, &ubuf, &target->thread.xstate->fxsave, 0, -1); @@ -154,7 +167,10 @@ int xfpregs_set(struct task_struct *target, const struct user_regset *regset, if (!cpu_has_fxsr) return -ENODEV; - init_fpu(target); + ret = init_fpu(target); + if (ret) + return ret; + set_stopped_child_used_math(target); ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, @@ -312,11 +328,14 @@ int fpregs_get(struct task_struct *target, const struct user_regset *regset, void *kbuf, void __user *ubuf) { struct user_i387_ia32_struct env; + int ret; if (!HAVE_HWFP) return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf); - init_fpu(target); + ret = init_fpu(target); + if (ret) + return ret; if (!cpu_has_fxsr) { return user_regset_copyout(&pos, &count, &kbuf, &ubuf, @@ -344,7 +363,10 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset, if (!HAVE_HWFP) return fpregs_soft_set(target, regset, pos, count, kbuf, ubuf); - init_fpu(target); + ret = init_fpu(target); + if (ret) + return ret; + set_stopped_child_used_math(target); if (!cpu_has_fxsr) { diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index ead24efbcb..0e613e7e7b 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -5,24 +5,34 @@ #include #include -static struct kmem_cache *task_xstate_cachep; +struct kmem_cache *task_xstate_cachep; int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) { *dst = *src; - dst->thread.xstate = kmem_cache_alloc(task_xstate_cachep, GFP_KERNEL); - if (!dst->thread.xstate) - return -ENOMEM; - WARN_ON((unsigned long)dst->thread.xstate & 15); - memcpy(dst->thread.xstate, src->thread.xstate, xstate_size); + if (src->thread.xstate) { + dst->thread.xstate = kmem_cache_alloc(task_xstate_cachep, + GFP_KERNEL); + if (!dst->thread.xstate) + return -ENOMEM; + WARN_ON((unsigned long)dst->thread.xstate & 15); + memcpy(dst->thread.xstate, src->thread.xstate, xstate_size); + } return 0; } -void free_thread_info(struct thread_info *ti) +void free_thread_xstate(struct task_struct *tsk) { - kmem_cache_free(task_xstate_cachep, ti->task->thread.xstate); - ti->task->thread.xstate = NULL; + if (tsk->thread.xstate) { + kmem_cache_free(task_xstate_cachep, tsk->thread.xstate); + tsk->thread.xstate = NULL; + } +} + +void free_thread_info(struct thread_info *ti) +{ + free_thread_xstate(ti->task); free_pages((unsigned long)(ti), get_order(THREAD_SIZE)); } diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index 3890a5dd25..7adad088e3 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -521,6 +521,10 @@ start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp) regs->cs = __USER_CS; regs->ip = new_ip; regs->sp = new_sp; + /* + * Free the old FP and other extended state + */ + free_thread_xstate(current); } EXPORT_SYMBOL_GPL(start_thread); diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index b795e831af..891af1a1b4 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -533,6 +533,10 @@ start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp) regs->ss = __USER_DS; regs->flags = 0x200; set_fs(USER_DS); + /* + * Free the old FP and other extended state + */ + free_thread_xstate(current); } EXPORT_SYMBOL_GPL(start_thread); diff --git a/arch/x86/kernel/traps_32.c b/arch/x86/kernel/traps_32.c index 8d136a73ce..471e694d67 100644 --- a/arch/x86/kernel/traps_32.c +++ b/arch/x86/kernel/traps_32.c @@ -1148,9 +1148,22 @@ asmlinkage void math_state_restore(void) struct thread_info *thread = current_thread_info(); struct task_struct *tsk = thread->task; + if (!tsk_used_math(tsk)) { + local_irq_enable(); + /* + * does a slab alloc which can sleep + */ + if (init_fpu(tsk)) { + /* + * ran out of memory! + */ + do_group_exit(SIGKILL); + return; + } + local_irq_disable(); + } + clts(); /* Allow maths ops (or we recurse) */ - if (!tsk_used_math(tsk)) - init_fpu(tsk); restore_fpu(tsk); thread->status |= TS_USEDFPU; /* So we fnsave on switch_to() */ tsk->fpu_counter++; diff --git a/arch/x86/kernel/traps_64.c b/arch/x86/kernel/traps_64.c index dc0cb497ee..adff76ea97 100644 --- a/arch/x86/kernel/traps_64.c +++ b/arch/x86/kernel/traps_64.c @@ -1124,10 +1124,23 @@ asmlinkage void __attribute__((weak)) mce_threshold_interrupt(void) asmlinkage void math_state_restore(void) { struct task_struct *me = current; - clts(); /* Allow maths ops (or we recurse) */ - if (!used_math()) - init_fpu(me); + if (!used_math()) { + local_irq_enable(); + /* + * does a slab alloc which can sleep + */ + if (init_fpu(me)) { + /* + * ran out of memory! + */ + do_group_exit(SIGKILL); + return; + } + local_irq_disable(); + } + + clts(); /* Allow maths ops (or we recurse) */ restore_fpu_checking(&me->thread.xstate->fxsave); task_thread_info(me)->status |= TS_USEDFPU; me->fpu_counter++; diff --git a/include/asm-x86/i387.h b/include/asm-x86/i387.h index 382a5fa9d4..4be7b58b1e 100644 --- a/include/asm-x86/i387.h +++ b/include/asm-x86/i387.h @@ -21,7 +21,7 @@ extern void fpu_init(void); extern void mxcsr_feature_mask_init(void); -extern void init_fpu(struct task_struct *child); +extern int init_fpu(struct task_struct *child); extern asmlinkage void math_state_restore(void); extern void init_thread_xstate(void); diff --git a/include/asm-x86/processor.h b/include/asm-x86/processor.h index 99d2978857..e6bf92ddeb 100644 --- a/include/asm-x86/processor.h +++ b/include/asm-x86/processor.h @@ -366,6 +366,8 @@ DECLARE_PER_CPU(struct orig_ist, orig_ist); extern void print_cpu_info(struct cpuinfo_x86 *); extern unsigned int xstate_size; +extern void free_thread_xstate(struct task_struct *); +extern struct kmem_cache *task_xstate_cachep; extern void init_scattered_cpuid_features(struct cpuinfo_x86 *c); extern unsigned int init_intel_cacheinfo(struct cpuinfo_x86 *c); extern unsigned short num_cache_leaves; -- 2.39.5