/* * 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/uaccess.h> #include <asm/ptrace.h> #include <asm/i387.h> #include <asm/fpu-internal.h> #include <asm/user.h> #ifdef CONFIG_X86_64 # include <asm/sigcontext32.h> # include <asm/user32.h> #else # define save_i387_xstate_ia32 save_i387_xstate # define restore_i387_xstate_ia32 restore_i387_xstate # define _fpstate_ia32 _fpstate # define _xstate_ia32 _xstate # define sig_xstate_ia32_size sig_xstate_size # define fx_sw_reserved_ia32 fx_sw_reserved # define user_i387_ia32_struct user_i387_struct # define user32_fxsr_struct user_fxsr_struct #endif /* * Were we in an interrupt that interrupted kernel mode? * * 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). */ static inline bool interrupted_kernel_fpu_idle(void) { 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_vm(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; WARN_ON_ONCE(!irq_fpu_usable()); preempt_disable(); if (__thread_has_fpu(me)) { __save_init_fpu(me); __thread_clear_has_fpu(me); /* We do 'stts()' in kernel_fpu_end() */ } else { this_cpu_write(fpu_owner_task, NULL); clts(); } } EXPORT_SYMBOL(kernel_fpu_begin); void kernel_fpu_end(void) { stts(); preempt_enable(); } EXPORT_SYMBOL(kernel_fpu_end); void unlazy_fpu(struct task_struct *tsk) { preempt_disable(); if (__thread_has_fpu(tsk)) { __save_init_fpu(tsk); __thread_fpu_end(tsk); } else tsk->fpu_counter = 0; preempt_enable(); } EXPORT_SYMBOL(unlazy_fpu); #ifdef CONFIG_MATH_EMULATION # define HAVE_HWFP (boot_cpu_data.hard_math) #else # define HAVE_HWFP 1 #endif static unsigned int mxcsr_feature_mask __read_mostly = 0xffffffffu; unsigned int xstate_size; EXPORT_SYMBOL_GPL(xstate_size); unsigned int sig_xstate_ia32_size = sizeof(struct _fpstate_ia32); static struct i387_fxsave_struct fx_scratch __cpuinitdata; static void __cpuinit mxcsr_feature_mask_init(void) { unsigned long mask = 0; clts(); 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; stts(); } static void __cpuinit init_thread_xstate(void) { /* * Note that xstate_size might be overwriten later during * xsave_init(). */ if (!HAVE_HWFP) { /* * 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); } /* * Called at bootup to set up the initial FPU state that is later cloned * into all processes. */ void __cpuinit fpu_init(void) { unsigned long cr0; unsigned long cr4_mask = 0; if (cpu_has_fxsr) cr4_mask |= X86_CR4_OSFXSR; if (cpu_has_xmm) cr4_mask |= X86_CR4_OSXMMEXCPT; if (cr4_mask) set_in_cr4(cr4_mask); cr0 = read_cr0(); cr0 &= ~(X86_CR0_TS|X86_CR0_EM); /* clear TS and EM */ if (!HAVE_HWFP) cr0 |= X86_CR0_EM; write_cr0(cr0); if (!smp_processor_id()) init_thread_xstate(); mxcsr_feature_mask_init(); /* clean state in init */ current_thread_info()->status = 0; clear_used_math(); } void fpu_finit(struct fpu *fpu) { if (!HAVE_HWFP) { finit_soft_fpu(&fpu->state->soft); return; } if (cpu_has_fxsr) { struct i387_fxsave_struct *fx = &fpu->state->fxsave; memset(fx, 0, xstate_size); fx->cwd = 0x37f; if (cpu_has_xmm) fx->mxcsr = MXCSR_DEFAULT; } else { struct i387_fsave_struct *fp = &fpu->state->fsave; memset(fp, 0, xstate_size); 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 (HAVE_HWFP && tsk == current) unlazy_fpu(tsk); tsk->thread.fpu.last_cpu = ~0; 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) { int ret; if (!cpu_has_xsave) return -ENODEV; ret = init_fpu(target); if (ret) return ret; /* * 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(&target->thread.fpu.state->fxsave.sw_reserved, xstate_fx_sw_bytes, sizeof(xstate_fx_sw_bytes)); /* * Copy the xstate memory layout. */ ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &target->thread.fpu.state->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) { int ret; struct xsave_hdr_struct *xsave_hdr; if (!cpu_has_xsave) return -ENODEV; ret = init_fpu(target); if (ret) return ret; ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &target->thread.fpu.state->xsave, 0, -1); /* * mxcsr reserved bits must be masked to zero for security reasons. */ target->thread.fpu.state->fxsave.mxcsr &= mxcsr_feature_mask; xsave_hdr = &target->thread.fpu.state->xsave.xsave_hdr; xsave_hdr->xstate_bv &= pcntxt_mask; /* * These bits must be zero. */ xsave_hdr->reserved1[0] = xsave_hdr->reserved1[1] = 0; 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. */ static 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])); } static 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 (!HAVE_HWFP) 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 (!HAVE_HWFP) 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; } /* * Signal frame handlers. */ static inline int save_i387_fsave(struct _fpstate_ia32 __user *buf) { struct task_struct *tsk = current; struct i387_fsave_struct *fp = &tsk->thread.fpu.state->fsave; fp->status = fp->swd; if (__copy_to_user(buf, fp, sizeof(struct i387_fsave_struct))) return -1; return 1; } static int save_i387_fxsave(struct _fpstate_ia32 __user *buf) { struct task_struct *tsk = current; struct i387_fxsave_struct *fx = &tsk->thread.fpu.state->fxsave; struct user_i387_ia32_struct env; int err = 0; convert_from_fxsr(&env, tsk); if (__copy_to_user(buf, &env, sizeof(env))) return -1; err |= __put_user(fx->swd, &buf->status); err |= __put_user(X86_FXSR_MAGIC, &buf->magic); if (err) return -1; if (__copy_to_user(&buf->_fxsr_env[0], fx, xstate_size)) return -1; return 1; } static int save_i387_xsave(void __user *buf) { struct task_struct *tsk = current; struct _fpstate_ia32 __user *fx = buf; int err = 0; sanitize_i387_state(tsk); /* * For legacy compatible, we always set FP/SSE bits in the bit * vector while saving the state to the user context. * This will enable us capturing any changes(during sigreturn) to * the FP/SSE bits by the legacy applications which don't touch * xstate_bv in the xsave header. * * xsave aware applications can change the xstate_bv in the xsave * header as well as change any contents in the memory layout. * xrestore as part of sigreturn will capture all the changes. */ tsk->thread.fpu.state->xsave.xsave_hdr.xstate_bv |= XSTATE_FPSSE; if (save_i387_fxsave(fx) < 0) return -1; err = __copy_to_user(&fx->sw_reserved, &fx_sw_reserved_ia32, sizeof(struct _fpx_sw_bytes)); err |= __put_user(FP_XSTATE_MAGIC2, (__u32 __user *) (buf + sig_xstate_ia32_size - FP_XSTATE_MAGIC2_SIZE)); if (err) return -1; return 1; } int save_i387_xstate_ia32(void __user *buf) { struct _fpstate_ia32 __user *fp = (struct _fpstate_ia32 __user *) buf; struct task_struct *tsk = current; if (!used_math()) return 0; if (!access_ok(VERIFY_WRITE, buf, sig_xstate_ia32_size)) return -EACCES; /* * This will cause a "finit" to be triggered by the next * attempted FPU operation by the 'current' process. */ clear_used_math(); if (!HAVE_HWFP) { return fpregs_soft_get(current, NULL, 0, sizeof(struct user_i387_ia32_struct), NULL, fp) ? -1 : 1; } unlazy_fpu(tsk); if (cpu_has_xsave) return save_i387_xsave(fp); if (cpu_has_fxsr) return save_i387_fxsave(fp); else return save_i387_fsave(fp); } static inline int restore_i387_fsave(struct _fpstate_ia32 __user *buf) { struct task_struct *tsk = current; return __copy_from_user(&tsk->thread.fpu.state->fsave, buf, sizeof(struct i387_fsave_struct)); } static int restore_i387_fxsave(struct _fpstate_ia32 __user *buf, unsigned int size) { struct task_struct *tsk = current; struct user_i387_ia32_struct env; int err; err = __copy_from_user(&tsk->thread.fpu.state->fxsave, &buf->_fxsr_env[0], size); /* mxcsr reserved bits must be masked to zero for security reasons */ tsk->thread.fpu.state->fxsave.mxcsr &= mxcsr_feature_mask; if (err || __copy_from_user(&env, buf, sizeof(env))) return 1; convert_to_fxsr(tsk, &env); return 0; } static int restore_i387_xsave(void __user *buf) { struct _fpx_sw_bytes fx_sw_user; struct _fpstate_ia32 __user *fx_user = ((struct _fpstate_ia32 __user *) buf); struct i387_fxsave_struct __user *fx = (struct i387_fxsave_struct __user *) &fx_user->_fxsr_env[0]; struct xsave_hdr_struct *xsave_hdr = ¤t->thread.fpu.state->xsave.xsave_hdr; u64 mask; int err; if (check_for_xstate(fx, buf, &fx_sw_user)) goto fx_only; mask = fx_sw_user.xstate_bv; err = restore_i387_fxsave(buf, fx_sw_user.xstate_size); xsave_hdr->xstate_bv &= pcntxt_mask; /* * These bits must be zero. */ xsave_hdr->reserved1[0] = xsave_hdr->reserved1[1] = 0; /* * Init the state that is not present in the memory layout * and enabled by the OS. */ mask = ~(pcntxt_mask & ~mask); xsave_hdr->xstate_bv &= mask; return err; fx_only: /* * Couldn't find the extended state information in the memory * layout. Restore the FP/SSE and init the other extended state * enabled by the OS. */ xsave_hdr->xstate_bv = XSTATE_FPSSE; return restore_i387_fxsave(buf, sizeof(struct i387_fxsave_struct)); } int restore_i387_xstate_ia32(void __user *buf) { int err; struct task_struct *tsk = current; struct _fpstate_ia32 __user *fp = (struct _fpstate_ia32 __user *) buf; if (HAVE_HWFP) clear_fpu(tsk); if (!buf) { if (used_math()) { clear_fpu(tsk); clear_used_math(); } return 0; } else if (!access_ok(VERIFY_READ, buf, sig_xstate_ia32_size)) return -EACCES; if (!used_math()) { err = init_fpu(tsk); if (err) return err; } if (HAVE_HWFP) { if (cpu_has_xsave) err = restore_i387_xsave(buf); else if (cpu_has_fxsr) err = restore_i387_fxsave(fp, sizeof(struct i387_fxsave_struct)); else err = restore_i387_fsave(fp); } else { err = fpregs_soft_set(current, NULL, 0, sizeof(struct user_i387_ia32_struct), NULL, fp) != 0; } set_used_math(); return err; } /* * 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 */