| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * FPU register's regset abstraction, for ptrace, core dumps, etc. |
| */ |
| #include <asm/fpu/internal.h> |
| #include <asm/fpu/signal.h> |
| #include <asm/fpu/regset.h> |
| #include <asm/fpu/xstate.h> |
| #include <linux/sched/task_stack.h> |
| |
| /* |
| * The xstateregs_active() routine is the same as the regset_fpregs_active() routine, |
| * as the "regset->n" for the xstate regset will be updated based on the feature |
| * capabilities supported by the xsave. |
| */ |
| int regset_fpregs_active(struct task_struct *target, const struct user_regset *regset) |
| { |
| return regset->n; |
| } |
| |
| int regset_xregset_fpregs_active(struct task_struct *target, const struct user_regset *regset) |
| { |
| if (boot_cpu_has(X86_FEATURE_FXSR)) |
| return regset->n; |
| else |
| return 0; |
| } |
| |
| int xfpregs_get(struct task_struct *target, const struct user_regset *regset, |
| unsigned int pos, unsigned int count, |
| void *kbuf, void __user *ubuf) |
| { |
| struct fpu *fpu = &target->thread.fpu; |
| |
| if (!boot_cpu_has(X86_FEATURE_FXSR)) |
| return -ENODEV; |
| |
| fpu__prepare_read(fpu); |
| fpstate_sanitize_xstate(fpu); |
| |
| return user_regset_copyout(&pos, &count, &kbuf, &ubuf, |
| &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) |
| { |
| struct fpu *fpu = &target->thread.fpu; |
| int ret; |
| |
| if (!boot_cpu_has(X86_FEATURE_FXSR)) |
| return -ENODEV; |
| |
| fpu__prepare_write(fpu); |
| fpstate_sanitize_xstate(fpu); |
| |
| ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, |
| &fpu->state.fxsave, 0, -1); |
| |
| /* |
| * mxcsr reserved bits must be masked to zero for security reasons. |
| */ |
| fpu->state.fxsave.mxcsr &= mxcsr_feature_mask; |
| |
| /* |
| * update the header bits in the xsave header, indicating the |
| * presence of FP and SSE state. |
| */ |
| if (boot_cpu_has(X86_FEATURE_XSAVE)) |
| fpu->state.xsave.header.xfeatures |= XFEATURE_MASK_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 fpu *fpu = &target->thread.fpu; |
| struct xregs_state *xsave; |
| int ret; |
| |
| if (!boot_cpu_has(X86_FEATURE_XSAVE)) |
| return -ENODEV; |
| |
| xsave = &fpu->state.xsave; |
| |
| fpu__prepare_read(fpu); |
| |
| if (using_compacted_format()) { |
| if (kbuf) |
| ret = copy_xstate_to_kernel(kbuf, xsave, pos, count); |
| else |
| ret = copy_xstate_to_user(ubuf, xsave, pos, count); |
| } else { |
| fpstate_sanitize_xstate(fpu); |
| /* |
| * Copy the 48 bytes defined by the software into the xsave |
| * area in the thread struct, so that we can copy the whole |
| * area to 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 fpu *fpu = &target->thread.fpu; |
| struct xregs_state *xsave; |
| int ret; |
| |
| if (!boot_cpu_has(X86_FEATURE_XSAVE)) |
| return -ENODEV; |
| |
| /* |
| * A whole standard-format XSAVE buffer is needed: |
| */ |
| if ((pos != 0) || (count < fpu_user_xstate_size)) |
| return -EFAULT; |
| |
| xsave = &fpu->state.xsave; |
| |
| fpu__prepare_write(fpu); |
| |
| if (using_compacted_format()) { |
| if (kbuf) |
| ret = copy_kernel_to_xstate(xsave, kbuf); |
| else |
| ret = copy_user_to_xstate(xsave, ubuf); |
| } else { |
| ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, xsave, 0, -1); |
| if (!ret) |
| ret = validate_user_xstate_header(&xsave->header); |
| } |
| |
| /* |
| * mxcsr reserved bits must be masked to zero for security reasons. |
| */ |
| xsave->i387.mxcsr &= mxcsr_feature_mask; |
| |
| /* |
| * In case of failure, mark all states as init: |
| */ |
| if (ret) |
| fpstate_init(&fpu->state); |
| |
| 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 fxregs_state *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 fxregs_state *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 fxregs_state *fxsave, |
| const struct user_i387_ia32_struct *env) |
| |
| { |
| 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 fpu *fpu = &target->thread.fpu; |
| struct user_i387_ia32_struct env; |
| |
| fpu__prepare_read(fpu); |
| |
| if (!boot_cpu_has(X86_FEATURE_FPU)) |
| return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf); |
| |
| if (!boot_cpu_has(X86_FEATURE_FXSR)) |
| return user_regset_copyout(&pos, &count, &kbuf, &ubuf, |
| &fpu->state.fsave, 0, |
| -1); |
| |
| fpstate_sanitize_xstate(fpu); |
| |
| 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 fpu *fpu = &target->thread.fpu; |
| struct user_i387_ia32_struct env; |
| int ret; |
| |
| fpu__prepare_write(fpu); |
| fpstate_sanitize_xstate(fpu); |
| |
| if (!boot_cpu_has(X86_FEATURE_FPU)) |
| return fpregs_soft_set(target, regset, pos, count, kbuf, ubuf); |
| |
| if (!boot_cpu_has(X86_FEATURE_FXSR)) |
| return user_regset_copyin(&pos, &count, &kbuf, &ubuf, |
| &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->thread.fpu.state.fxsave, &env); |
| |
| /* |
| * update the header bit in the xsave header, indicating the |
| * presence of FP. |
| */ |
| if (boot_cpu_has(X86_FEATURE_XSAVE)) |
| fpu->state.xsave.header.xfeatures |= XFEATURE_MASK_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 *ufpu) |
| { |
| struct task_struct *tsk = current; |
| |
| return !fpregs_get(tsk, NULL, 0, sizeof(struct user_i387_ia32_struct), |
| ufpu, NULL); |
| } |
| EXPORT_SYMBOL(dump_fpu); |
| |
| #endif /* CONFIG_X86_32 || CONFIG_IA32_EMULATION */ |