+++ /dev/null
-/*
- * Copyright (C) 1994 Linus Torvalds
- *
- * Pentium III FXSR, SSE support
- * General FPU state handling cleanups
- * Gareth Hughes <gareth@valinux.com>, May 2000
- */
-#include <linux/module.h>
-#include <linux/regset.h>
-#include <linux/sched.h>
-#include <linux/slab.h>
-
-#include <asm/sigcontext.h>
-#include <asm/processor.h>
-#include <asm/math_emu.h>
-#include <asm/tlbflush.h>
-#include <asm/uaccess.h>
-#include <asm/ptrace.h>
-#include <asm/i387.h>
-#include <asm/fpu-internal.h>
-#include <asm/user.h>
-
-static DEFINE_PER_CPU(bool, in_kernel_fpu);
-
-void kernel_fpu_disable(void)
-{
- WARN_ON(this_cpu_read(in_kernel_fpu));
- this_cpu_write(in_kernel_fpu, true);
-}
-
-void kernel_fpu_enable(void)
-{
- this_cpu_write(in_kernel_fpu, false);
-}
-
-/*
- * Were we in an interrupt that interrupted kernel mode?
- *
- * On others, we can do a kernel_fpu_begin/end() pair *ONLY* if that
- * pair does nothing at all: the thread must not have fpu (so
- * that we don't try to save the FPU state), and TS must
- * be set (so that the clts/stts pair does nothing that is
- * visible in the interrupted kernel thread).
- *
- * Except for the eagerfpu case when we return true; in the likely case
- * the thread has FPU but we are not going to set/clear TS.
- */
-static inline bool interrupted_kernel_fpu_idle(void)
-{
- if (this_cpu_read(in_kernel_fpu))
- return false;
-
- if (use_eager_fpu())
- return true;
-
- return !__thread_has_fpu(current) &&
- (read_cr0() & X86_CR0_TS);
-}
-
-/*
- * Were we in user mode (or vm86 mode) when we were
- * interrupted?
- *
- * Doing kernel_fpu_begin/end() is ok if we are running
- * in an interrupt context from user mode - we'll just
- * save the FPU state as required.
- */
-static inline bool interrupted_user_mode(void)
-{
- struct pt_regs *regs = get_irq_regs();
- return regs && user_mode(regs);
-}
-
-/*
- * Can we use the FPU in kernel mode with the
- * whole "kernel_fpu_begin/end()" sequence?
- *
- * It's always ok in process context (ie "not interrupt")
- * but it is sometimes ok even from an irq.
- */
-bool irq_fpu_usable(void)
-{
- return !in_interrupt() ||
- interrupted_user_mode() ||
- interrupted_kernel_fpu_idle();
-}
-EXPORT_SYMBOL(irq_fpu_usable);
-
-void __kernel_fpu_begin(void)
-{
- struct task_struct *me = current;
-
- this_cpu_write(in_kernel_fpu, true);
-
- if (__thread_has_fpu(me)) {
- __save_init_fpu(me);
- } else {
- this_cpu_write(fpu_owner_task, NULL);
- if (!use_eager_fpu())
- clts();
- }
-}
-EXPORT_SYMBOL(__kernel_fpu_begin);
-
-void __kernel_fpu_end(void)
-{
- struct task_struct *me = current;
-
- if (__thread_has_fpu(me)) {
- if (WARN_ON(restore_fpu_checking(me)))
- fpu_reset_state(me);
- } else if (!use_eager_fpu()) {
- stts();
- }
-
- this_cpu_write(in_kernel_fpu, false);
-}
-EXPORT_SYMBOL(__kernel_fpu_end);
-
-void unlazy_fpu(struct task_struct *tsk)
-{
- preempt_disable();
- if (__thread_has_fpu(tsk)) {
- if (use_eager_fpu()) {
- __save_fpu(tsk);
- } else {
- __save_init_fpu(tsk);
- __thread_fpu_end(tsk);
- }
- }
- preempt_enable();
-}
-EXPORT_SYMBOL(unlazy_fpu);
-
-unsigned int mxcsr_feature_mask __read_mostly = 0xffffffffu;
-unsigned int xstate_size;
-EXPORT_SYMBOL_GPL(xstate_size);
-static struct i387_fxsave_struct fx_scratch;
-
-static void mxcsr_feature_mask_init(void)
-{
- unsigned long mask = 0;
-
- if (cpu_has_fxsr) {
- memset(&fx_scratch, 0, sizeof(struct i387_fxsave_struct));
- asm volatile("fxsave %0" : "+m" (fx_scratch));
- mask = fx_scratch.mxcsr_mask;
- if (mask == 0)
- mask = 0x0000ffbf;
- }
- mxcsr_feature_mask &= mask;
-}
-
-static void init_thread_xstate(void)
-{
- /*
- * Note that xstate_size might be overwriten later during
- * xsave_init().
- */
-
- if (!cpu_has_fpu) {
- /*
- * Disable xsave as we do not support it if i387
- * emulation is enabled.
- */
- setup_clear_cpu_cap(X86_FEATURE_XSAVE);
- setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
- xstate_size = sizeof(struct i387_soft_struct);
- return;
- }
-
- if (cpu_has_fxsr)
- xstate_size = sizeof(struct i387_fxsave_struct);
- else
- xstate_size = sizeof(struct i387_fsave_struct);
-
- /*
- * Quirk: we don't yet handle the XSAVES* instructions
- * correctly, as we don't correctly convert between
- * standard and compacted format when interfacing
- * with user-space - so disable it for now.
- *
- * The difference is small: with recent CPUs the
- * compacted format is only marginally smaller than
- * the standard FPU state format.
- *
- * ( This is easy to backport while we are fixing
- * XSAVES* support. )
- */
- setup_clear_cpu_cap(X86_FEATURE_XSAVES);
-}
-
-/*
- * Called at bootup to set up the initial FPU state that is later cloned
- * into all processes.
- */
-
-void fpu_init(void)
-{
- unsigned long cr0;
- unsigned long cr4_mask = 0;
-
-#ifndef CONFIG_MATH_EMULATION
- if (!cpu_has_fpu) {
- pr_emerg("No FPU found and no math emulation present\n");
- pr_emerg("Giving up\n");
- for (;;)
- asm volatile("hlt");
- }
-#endif
- if (cpu_has_fxsr)
- cr4_mask |= X86_CR4_OSFXSR;
- if (cpu_has_xmm)
- cr4_mask |= X86_CR4_OSXMMEXCPT;
- if (cr4_mask)
- cr4_set_bits(cr4_mask);
-
- cr0 = read_cr0();
- cr0 &= ~(X86_CR0_TS|X86_CR0_EM); /* clear TS and EM */
- if (!cpu_has_fpu)
- cr0 |= X86_CR0_EM;
- write_cr0(cr0);
-
- /*
- * init_thread_xstate is only called once to avoid overriding
- * xstate_size during boot time or during CPU hotplug.
- */
- if (xstate_size == 0)
- init_thread_xstate();
-
- mxcsr_feature_mask_init();
- xsave_init();
- eager_fpu_init();
-}
-
-void fpu_finit(struct fpu *fpu)
-{
- if (!cpu_has_fpu) {
- finit_soft_fpu(&fpu->state->soft);
- return;
- }
-
- memset(fpu->state, 0, xstate_size);
-
- if (cpu_has_fxsr) {
- fx_finit(&fpu->state->fxsave);
- } else {
- struct i387_fsave_struct *fp = &fpu->state->fsave;
- fp->cwd = 0xffff037fu;
- fp->swd = 0xffff0000u;
- fp->twd = 0xffffffffu;
- fp->fos = 0xffff0000u;
- }
-}
-EXPORT_SYMBOL_GPL(fpu_finit);
-
-/*
- * The _current_ task is using the FPU for the first time
- * so initialize it and set the mxcsr to its default
- * value at reset if we support XMM instructions and then
- * remember the current task has used the FPU.
- */
-int init_fpu(struct task_struct *tsk)
-{
- int ret;
-
- if (tsk_used_math(tsk)) {
- if (cpu_has_fpu && tsk == current)
- unlazy_fpu(tsk);
- task_disable_lazy_fpu_restore(tsk);
- return 0;
- }
-
- /*
- * Memory allocation at the first usage of the FPU and other state.
- */
- ret = fpu_alloc(&tsk->thread.fpu);
- if (ret)
- return ret;
-
- fpu_finit(&tsk->thread.fpu);
-
- set_stopped_child_used_math(tsk);
- return 0;
-}
-EXPORT_SYMBOL_GPL(init_fpu);
-
-/*
- * The xstateregs_active() routine is the same as the fpregs_active() routine,
- * as the "regset->n" for the xstate regset will be updated based on the feature
- * capabilites supported by the xsave.
- */
-int fpregs_active(struct task_struct *target, const struct user_regset *regset)
-{
- return tsk_used_math(target) ? regset->n : 0;
-}
-
-int xfpregs_active(struct task_struct *target, const struct user_regset *regset)
-{
- return (cpu_has_fxsr && tsk_used_math(target)) ? regset->n : 0;
-}
-
-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;
-
- ret = init_fpu(target);
- if (ret)
- return ret;
-
- sanitize_i387_state(target);
-
- return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
- &target->thread.fpu.state->fxsave, 0, -1);
-}
-
-int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
- unsigned int pos, unsigned int count,
- const void *kbuf, const void __user *ubuf)
-{
- int ret;
-
- if (!cpu_has_fxsr)
- return -ENODEV;
-
- ret = init_fpu(target);
- if (ret)
- return ret;
-
- sanitize_i387_state(target);
-
- ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
- &target->thread.fpu.state->fxsave, 0, -1);
-
- /*
- * mxcsr reserved bits must be masked to zero for security reasons.
- */
- target->thread.fpu.state->fxsave.mxcsr &= mxcsr_feature_mask;
-
- /*
- * update the header bits in the xsave header, indicating the
- * presence of FP and SSE state.
- */
- if (cpu_has_xsave)
- target->thread.fpu.state->xsave.xsave_hdr.xstate_bv |= XSTATE_FPSSE;
-
- return ret;
-}
-
-int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
- unsigned int pos, unsigned int count,
- void *kbuf, void __user *ubuf)
-{
- struct xsave_struct *xsave;
- int ret;
-
- if (!cpu_has_xsave)
- return -ENODEV;
-
- ret = init_fpu(target);
- if (ret)
- return ret;
-
- xsave = &target->thread.fpu.state->xsave;
-
- /*
- * Copy the 48bytes defined by the software first into the xstate
- * memory layout in the thread struct, so that we can copy the entire
- * xstateregs to the user using one user_regset_copyout().
- */
- memcpy(&xsave->i387.sw_reserved,
- xstate_fx_sw_bytes, sizeof(xstate_fx_sw_bytes));
- /*
- * Copy the xstate memory layout.
- */
- ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
- return ret;
-}
-
-int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
- unsigned int pos, unsigned int count,
- const void *kbuf, const void __user *ubuf)
-{
- struct xsave_struct *xsave;
- int ret;
-
- if (!cpu_has_xsave)
- return -ENODEV;
-
- ret = init_fpu(target);
- if (ret)
- return ret;
-
- xsave = &target->thread.fpu.state->xsave;
-
- ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
- /*
- * mxcsr reserved bits must be masked to zero for security reasons.
- */
- xsave->i387.mxcsr &= mxcsr_feature_mask;
- xsave->xsave_hdr.xstate_bv &= pcntxt_mask;
- /*
- * These bits must be zero.
- */
- memset(&xsave->xsave_hdr.reserved, 0, 48);
- return ret;
-}
-
-#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
-
-/*
- * FPU tag word conversions.
- */
-
-static inline unsigned short twd_i387_to_fxsr(unsigned short twd)
-{
- unsigned int tmp; /* to avoid 16 bit prefixes in the code */
-
- /* Transform each pair of bits into 01 (valid) or 00 (empty) */
- tmp = ~twd;
- tmp = (tmp | (tmp>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
- /* and move the valid bits to the lower byte. */
- tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */
- tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
- tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */
-
- return tmp;
-}
-
-#define FPREG_ADDR(f, n) ((void *)&(f)->st_space + (n) * 16)
-#define FP_EXP_TAG_VALID 0
-#define FP_EXP_TAG_ZERO 1
-#define FP_EXP_TAG_SPECIAL 2
-#define FP_EXP_TAG_EMPTY 3
-
-static inline u32 twd_fxsr_to_i387(struct i387_fxsave_struct *fxsave)
-{
- struct _fpxreg *st;
- u32 tos = (fxsave->swd >> 11) & 7;
- u32 twd = (unsigned long) fxsave->twd;
- u32 tag;
- u32 ret = 0xffff0000u;
- int i;
-
- for (i = 0; i < 8; i++, twd >>= 1) {
- if (twd & 0x1) {
- st = FPREG_ADDR(fxsave, (i - tos) & 7);
-
- switch (st->exponent & 0x7fff) {
- case 0x7fff:
- tag = FP_EXP_TAG_SPECIAL;
- break;
- case 0x0000:
- if (!st->significand[0] &&
- !st->significand[1] &&
- !st->significand[2] &&
- !st->significand[3])
- tag = FP_EXP_TAG_ZERO;
- else
- tag = FP_EXP_TAG_SPECIAL;
- break;
- default:
- if (st->significand[3] & 0x8000)
- tag = FP_EXP_TAG_VALID;
- else
- tag = FP_EXP_TAG_SPECIAL;
- break;
- }
- } else {
- tag = FP_EXP_TAG_EMPTY;
- }
- ret |= tag << (2 * i);
- }
- return ret;
-}
-
-/*
- * FXSR floating point environment conversions.
- */
-
-void
-convert_from_fxsr(struct user_i387_ia32_struct *env, struct task_struct *tsk)
-{
- struct i387_fxsave_struct *fxsave = &tsk->thread.fpu.state->fxsave;
- struct _fpreg *to = (struct _fpreg *) &env->st_space[0];
- struct _fpxreg *from = (struct _fpxreg *) &fxsave->st_space[0];
- int i;
-
- env->cwd = fxsave->cwd | 0xffff0000u;
- env->swd = fxsave->swd | 0xffff0000u;
- env->twd = twd_fxsr_to_i387(fxsave);
-
-#ifdef CONFIG_X86_64
- env->fip = fxsave->rip;
- env->foo = fxsave->rdp;
- /*
- * should be actually ds/cs at fpu exception time, but
- * that information is not available in 64bit mode.
- */
- env->fcs = task_pt_regs(tsk)->cs;
- if (tsk == current) {
- savesegment(ds, env->fos);
- } else {
- env->fos = tsk->thread.ds;
- }
- env->fos |= 0xffff0000;
-#else
- env->fip = fxsave->fip;
- env->fcs = (u16) fxsave->fcs | ((u32) fxsave->fop << 16);
- env->foo = fxsave->foo;
- env->fos = fxsave->fos;
-#endif
-
- for (i = 0; i < 8; ++i)
- memcpy(&to[i], &from[i], sizeof(to[0]));
-}
-
-void convert_to_fxsr(struct task_struct *tsk,
- const struct user_i387_ia32_struct *env)
-
-{
- struct i387_fxsave_struct *fxsave = &tsk->thread.fpu.state->fxsave;
- struct _fpreg *from = (struct _fpreg *) &env->st_space[0];
- struct _fpxreg *to = (struct _fpxreg *) &fxsave->st_space[0];
- int i;
-
- fxsave->cwd = env->cwd;
- fxsave->swd = env->swd;
- fxsave->twd = twd_i387_to_fxsr(env->twd);
- fxsave->fop = (u16) ((u32) env->fcs >> 16);
-#ifdef CONFIG_X86_64
- fxsave->rip = env->fip;
- fxsave->rdp = env->foo;
- /* cs and ds ignored */
-#else
- fxsave->fip = env->fip;
- fxsave->fcs = (env->fcs & 0xffff);
- fxsave->foo = env->foo;
- fxsave->fos = env->fos;
-#endif
-
- for (i = 0; i < 8; ++i)
- memcpy(&to[i], &from[i], sizeof(from[0]));
-}
-
-int fpregs_get(struct task_struct *target, const struct user_regset *regset,
- unsigned int pos, unsigned int count,
- void *kbuf, void __user *ubuf)
-{
- struct user_i387_ia32_struct env;
- int ret;
-
- ret = init_fpu(target);
- if (ret)
- return ret;
-
- if (!static_cpu_has(X86_FEATURE_FPU))
- return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);
-
- if (!cpu_has_fxsr)
- return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
- &target->thread.fpu.state->fsave, 0,
- -1);
-
- sanitize_i387_state(target);
-
- if (kbuf && pos == 0 && count == sizeof(env)) {
- convert_from_fxsr(kbuf, target);
- return 0;
- }
-
- convert_from_fxsr(&env, target);
-
- return user_regset_copyout(&pos, &count, &kbuf, &ubuf, &env, 0, -1);
-}
-
-int fpregs_set(struct task_struct *target, const struct user_regset *regset,
- unsigned int pos, unsigned int count,
- const void *kbuf, const void __user *ubuf)
-{
- struct user_i387_ia32_struct env;
- int ret;
-
- ret = init_fpu(target);
- if (ret)
- return ret;
-
- sanitize_i387_state(target);
-
- if (!static_cpu_has(X86_FEATURE_FPU))
- return fpregs_soft_set(target, regset, pos, count, kbuf, ubuf);
-
- if (!cpu_has_fxsr)
- return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
- &target->thread.fpu.state->fsave, 0,
- -1);
-
- if (pos > 0 || count < sizeof(env))
- convert_from_fxsr(&env, target);
-
- ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &env, 0, -1);
- if (!ret)
- convert_to_fxsr(target, &env);
-
- /*
- * update the header bit in the xsave header, indicating the
- * presence of FP.
- */
- if (cpu_has_xsave)
- target->thread.fpu.state->xsave.xsave_hdr.xstate_bv |= XSTATE_FP;
- return ret;
-}
-
-/*
- * FPU state for core dumps.
- * This is only used for a.out dumps now.
- * It is declared generically using elf_fpregset_t (which is
- * struct user_i387_struct) but is in fact only used for 32-bit
- * dumps, so on 64-bit it is really struct user_i387_ia32_struct.
- */
-int dump_fpu(struct pt_regs *regs, struct user_i387_struct *fpu)
-{
- struct task_struct *tsk = current;
- int fpvalid;
-
- fpvalid = !!used_math();
- if (fpvalid)
- fpvalid = !fpregs_get(tsk, NULL,
- 0, sizeof(struct user_i387_ia32_struct),
- fpu, NULL);
-
- return fpvalid;
-}
-EXPORT_SYMBOL(dump_fpu);
-
-#endif /* CONFIG_X86_32 || CONFIG_IA32_EMULATION */
-
-static int __init no_387(char *s)
-{
- setup_clear_cpu_cap(X86_FEATURE_FPU);
- return 1;
-}
-
-__setup("no387", no_387);
-
-void fpu_detect(struct cpuinfo_x86 *c)
-{
- unsigned long cr0;
- u16 fsw, fcw;
-
- fsw = fcw = 0xffff;
-
- cr0 = read_cr0();
- cr0 &= ~(X86_CR0_TS | X86_CR0_EM);
- write_cr0(cr0);
-
- asm volatile("fninit ; fnstsw %0 ; fnstcw %1"
- : "+m" (fsw), "+m" (fcw));
-
- if (fsw == 0 && (fcw & 0x103f) == 0x003f)
- set_cpu_cap(c, X86_FEATURE_FPU);
- else
- clear_cpu_cap(c, X86_FEATURE_FPU);
-
- /* The final cr0 value is set in fpu_init() */
-}
Code Review / kvmfornfv.git / blobdiff