summaryrefslogtreecommitdiffstats
path: root/arch/x86/include/asm/fpu/internal.h
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--arch/x86/include/asm/fpu/internal.h590
1 files changed, 590 insertions, 0 deletions
diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
new file mode 100644
index 000000000..94c07151a
--- /dev/null
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -0,0 +1,590 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 1994 Linus Torvalds
+ *
+ * Pentium III FXSR, SSE support
+ * General FPU state handling cleanups
+ * Gareth Hughes <gareth@valinux.com>, May 2000
+ * x86-64 work by Andi Kleen 2002
+ */
+
+#ifndef _ASM_X86_FPU_INTERNAL_H
+#define _ASM_X86_FPU_INTERNAL_H
+
+#include <linux/compat.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+
+#include <asm/user.h>
+#include <asm/fpu/api.h>
+#include <asm/fpu/xstate.h>
+#include <asm/fpu/xcr.h>
+#include <asm/cpufeature.h>
+#include <asm/trace/fpu.h>
+
+/*
+ * High level FPU state handling functions:
+ */
+extern void fpu__prepare_read(struct fpu *fpu);
+extern void fpu__prepare_write(struct fpu *fpu);
+extern void fpu__save(struct fpu *fpu);
+extern int fpu__restore_sig(void __user *buf, int ia32_frame);
+extern void fpu__drop(struct fpu *fpu);
+extern int fpu__copy(struct task_struct *dst, struct task_struct *src);
+extern void fpu__clear_user_states(struct fpu *fpu);
+extern void fpu__clear_all(struct fpu *fpu);
+extern int fpu__exception_code(struct fpu *fpu, int trap_nr);
+
+/*
+ * Boot time FPU initialization functions:
+ */
+extern void fpu__init_cpu(void);
+extern void fpu__init_system_xstate(void);
+extern void fpu__init_cpu_xstate(void);
+extern void fpu__init_system(void);
+extern void fpu__init_check_bugs(void);
+extern void fpu__resume_cpu(void);
+extern u64 fpu__get_supported_xfeatures_mask(void);
+
+/*
+ * Debugging facility:
+ */
+#ifdef CONFIG_X86_DEBUG_FPU
+# define WARN_ON_FPU(x) WARN_ON_ONCE(x)
+#else
+# define WARN_ON_FPU(x) ({ (void)(x); 0; })
+#endif
+
+/*
+ * FPU related CPU feature flag helper routines:
+ */
+static __always_inline __pure bool use_xsaveopt(void)
+{
+ return static_cpu_has(X86_FEATURE_XSAVEOPT);
+}
+
+static __always_inline __pure bool use_xsave(void)
+{
+ return static_cpu_has(X86_FEATURE_XSAVE);
+}
+
+static __always_inline __pure bool use_fxsr(void)
+{
+ return static_cpu_has(X86_FEATURE_FXSR);
+}
+
+/*
+ * fpstate handling functions:
+ */
+
+extern union fpregs_state init_fpstate;
+
+extern void fpstate_init(union fpregs_state *state);
+#ifdef CONFIG_MATH_EMULATION
+extern void fpstate_init_soft(struct swregs_state *soft);
+#else
+static inline void fpstate_init_soft(struct swregs_state *soft) {}
+#endif
+
+static inline void fpstate_init_xstate(struct xregs_state *xsave)
+{
+ /*
+ * XRSTORS requires these bits set in xcomp_bv, or it will
+ * trigger #GP:
+ */
+ xsave->header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT | xfeatures_mask_all;
+}
+
+static inline void fpstate_init_fxstate(struct fxregs_state *fx)
+{
+ fx->cwd = 0x37f;
+ fx->mxcsr = MXCSR_DEFAULT;
+}
+extern void fpstate_sanitize_xstate(struct fpu *fpu);
+
+/* Returns 0 or the negated trap number, which results in -EFAULT for #PF */
+#define user_insn(insn, output, input...) \
+({ \
+ int err; \
+ \
+ might_fault(); \
+ \
+ asm volatile(ASM_STAC "\n" \
+ "1: " #insn "\n" \
+ "2: " ASM_CLAC "\n" \
+ ".section .fixup,\"ax\"\n" \
+ "3: negl %%eax\n" \
+ " jmp 2b\n" \
+ ".previous\n" \
+ _ASM_EXTABLE_FAULT(1b, 3b) \
+ : [err] "=a" (err), output \
+ : "0"(0), input); \
+ err; \
+})
+
+#define kernel_insn_err(insn, output, input...) \
+({ \
+ int err; \
+ asm volatile("1:" #insn "\n\t" \
+ "2:\n" \
+ ".section .fixup,\"ax\"\n" \
+ "3: movl $-1,%[err]\n" \
+ " jmp 2b\n" \
+ ".previous\n" \
+ _ASM_EXTABLE(1b, 3b) \
+ : [err] "=r" (err), output \
+ : "0"(0), input); \
+ err; \
+})
+
+#define kernel_insn(insn, output, input...) \
+ asm volatile("1:" #insn "\n\t" \
+ "2:\n" \
+ _ASM_EXTABLE_HANDLE(1b, 2b, ex_handler_fprestore) \
+ : output : input)
+
+static inline int copy_fregs_to_user(struct fregs_state __user *fx)
+{
+ return user_insn(fnsave %[fx]; fwait, [fx] "=m" (*fx), "m" (*fx));
+}
+
+static inline int copy_fxregs_to_user(struct fxregs_state __user *fx)
+{
+ if (IS_ENABLED(CONFIG_X86_32))
+ return user_insn(fxsave %[fx], [fx] "=m" (*fx), "m" (*fx));
+ else
+ return user_insn(fxsaveq %[fx], [fx] "=m" (*fx), "m" (*fx));
+
+}
+
+static inline void copy_kernel_to_fxregs(struct fxregs_state *fx)
+{
+ if (IS_ENABLED(CONFIG_X86_32))
+ kernel_insn(fxrstor %[fx], "=m" (*fx), [fx] "m" (*fx));
+ else
+ kernel_insn(fxrstorq %[fx], "=m" (*fx), [fx] "m" (*fx));
+}
+
+static inline int copy_kernel_to_fxregs_err(struct fxregs_state *fx)
+{
+ if (IS_ENABLED(CONFIG_X86_32))
+ return kernel_insn_err(fxrstor %[fx], "=m" (*fx), [fx] "m" (*fx));
+ else
+ return kernel_insn_err(fxrstorq %[fx], "=m" (*fx), [fx] "m" (*fx));
+}
+
+static inline int copy_user_to_fxregs(struct fxregs_state __user *fx)
+{
+ if (IS_ENABLED(CONFIG_X86_32))
+ return user_insn(fxrstor %[fx], "=m" (*fx), [fx] "m" (*fx));
+ else
+ return user_insn(fxrstorq %[fx], "=m" (*fx), [fx] "m" (*fx));
+}
+
+static inline void copy_kernel_to_fregs(struct fregs_state *fx)
+{
+ kernel_insn(frstor %[fx], "=m" (*fx), [fx] "m" (*fx));
+}
+
+static inline int copy_kernel_to_fregs_err(struct fregs_state *fx)
+{
+ return kernel_insn_err(frstor %[fx], "=m" (*fx), [fx] "m" (*fx));
+}
+
+static inline int copy_user_to_fregs(struct fregs_state __user *fx)
+{
+ return user_insn(frstor %[fx], "=m" (*fx), [fx] "m" (*fx));
+}
+
+static inline void copy_fxregs_to_kernel(struct fpu *fpu)
+{
+ if (IS_ENABLED(CONFIG_X86_32))
+ asm volatile( "fxsave %[fx]" : [fx] "=m" (fpu->state.fxsave));
+ else
+ asm volatile("fxsaveq %[fx]" : [fx] "=m" (fpu->state.fxsave));
+}
+
+static inline void fxsave(struct fxregs_state *fx)
+{
+ if (IS_ENABLED(CONFIG_X86_32))
+ asm volatile( "fxsave %[fx]" : [fx] "=m" (*fx));
+ else
+ asm volatile("fxsaveq %[fx]" : [fx] "=m" (*fx));
+}
+
+/* These macros all use (%edi)/(%rdi) as the single memory argument. */
+#define XSAVE ".byte " REX_PREFIX "0x0f,0xae,0x27"
+#define XSAVEOPT ".byte " REX_PREFIX "0x0f,0xae,0x37"
+#define XSAVES ".byte " REX_PREFIX "0x0f,0xc7,0x2f"
+#define XRSTOR ".byte " REX_PREFIX "0x0f,0xae,0x2f"
+#define XRSTORS ".byte " REX_PREFIX "0x0f,0xc7,0x1f"
+
+/*
+ * After this @err contains 0 on success or the negated trap number when
+ * the operation raises an exception. For faults this results in -EFAULT.
+ */
+#define XSTATE_OP(op, st, lmask, hmask, err) \
+ asm volatile("1:" op "\n\t" \
+ "xor %[err], %[err]\n" \
+ "2:\n\t" \
+ ".pushsection .fixup,\"ax\"\n\t" \
+ "3: negl %%eax\n\t" \
+ "jmp 2b\n\t" \
+ ".popsection\n\t" \
+ _ASM_EXTABLE_FAULT(1b, 3b) \
+ : [err] "=a" (err) \
+ : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \
+ : "memory")
+
+/*
+ * If XSAVES is enabled, it replaces XSAVEOPT because it supports a compact
+ * format and supervisor states in addition to modified optimization in
+ * XSAVEOPT.
+ *
+ * Otherwise, if XSAVEOPT is enabled, XSAVEOPT replaces XSAVE because XSAVEOPT
+ * supports modified optimization which is not supported by XSAVE.
+ *
+ * We use XSAVE as a fallback.
+ *
+ * The 661 label is defined in the ALTERNATIVE* macros as the address of the
+ * original instruction which gets replaced. We need to use it here as the
+ * address of the instruction where we might get an exception at.
+ */
+#define XSTATE_XSAVE(st, lmask, hmask, err) \
+ asm volatile(ALTERNATIVE_2(XSAVE, \
+ XSAVEOPT, X86_FEATURE_XSAVEOPT, \
+ XSAVES, X86_FEATURE_XSAVES) \
+ "\n" \
+ "xor %[err], %[err]\n" \
+ "3:\n" \
+ ".pushsection .fixup,\"ax\"\n" \
+ "4: movl $-2, %[err]\n" \
+ "jmp 3b\n" \
+ ".popsection\n" \
+ _ASM_EXTABLE(661b, 4b) \
+ : [err] "=r" (err) \
+ : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \
+ : "memory")
+
+/*
+ * Use XRSTORS to restore context if it is enabled. XRSTORS supports compact
+ * XSAVE area format.
+ */
+#define XSTATE_XRESTORE(st, lmask, hmask) \
+ asm volatile(ALTERNATIVE(XRSTOR, \
+ XRSTORS, X86_FEATURE_XSAVES) \
+ "\n" \
+ "3:\n" \
+ _ASM_EXTABLE_HANDLE(661b, 3b, ex_handler_fprestore)\
+ : \
+ : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \
+ : "memory")
+
+/*
+ * This function is called only during boot time when x86 caps are not set
+ * up and alternative can not be used yet.
+ */
+static inline void copy_kernel_to_xregs_booting(struct xregs_state *xstate)
+{
+ u64 mask = -1;
+ u32 lmask = mask;
+ u32 hmask = mask >> 32;
+ int err;
+
+ WARN_ON(system_state != SYSTEM_BOOTING);
+
+ if (boot_cpu_has(X86_FEATURE_XSAVES))
+ XSTATE_OP(XRSTORS, xstate, lmask, hmask, err);
+ else
+ XSTATE_OP(XRSTOR, xstate, lmask, hmask, err);
+
+ /*
+ * We should never fault when copying from a kernel buffer, and the FPU
+ * state we set at boot time should be valid.
+ */
+ WARN_ON_FPU(err);
+}
+
+/*
+ * Save processor xstate to xsave area.
+ */
+static inline void copy_xregs_to_kernel(struct xregs_state *xstate)
+{
+ u64 mask = xfeatures_mask_all;
+ u32 lmask = mask;
+ u32 hmask = mask >> 32;
+ int err;
+
+ WARN_ON_FPU(!alternatives_patched);
+
+ XSTATE_XSAVE(xstate, lmask, hmask, err);
+
+ /* We should never fault when copying to a kernel buffer: */
+ WARN_ON_FPU(err);
+}
+
+/*
+ * Restore processor xstate from xsave area.
+ */
+static inline void copy_kernel_to_xregs(struct xregs_state *xstate, u64 mask)
+{
+ u32 lmask = mask;
+ u32 hmask = mask >> 32;
+
+ XSTATE_XRESTORE(xstate, lmask, hmask);
+}
+
+/*
+ * Save xstate to user space xsave area.
+ *
+ * We don't use modified optimization because xrstor/xrstors might track
+ * a different application.
+ *
+ * We don't use compacted format xsave area for
+ * backward compatibility for old applications which don't understand
+ * compacted format of xsave area.
+ */
+static inline int copy_xregs_to_user(struct xregs_state __user *buf)
+{
+ u64 mask = xfeatures_mask_user();
+ u32 lmask = mask;
+ u32 hmask = mask >> 32;
+ int err;
+
+ /*
+ * Clear the xsave header first, so that reserved fields are
+ * initialized to zero.
+ */
+ err = __clear_user(&buf->header, sizeof(buf->header));
+ if (unlikely(err))
+ return -EFAULT;
+
+ stac();
+ XSTATE_OP(XSAVE, buf, lmask, hmask, err);
+ clac();
+
+ return err;
+}
+
+/*
+ * Restore xstate from user space xsave area.
+ */
+static inline int copy_user_to_xregs(struct xregs_state __user *buf, u64 mask)
+{
+ struct xregs_state *xstate = ((__force struct xregs_state *)buf);
+ u32 lmask = mask;
+ u32 hmask = mask >> 32;
+ int err;
+
+ stac();
+ XSTATE_OP(XRSTOR, xstate, lmask, hmask, err);
+ clac();
+
+ return err;
+}
+
+/*
+ * Restore xstate from kernel space xsave area, return an error code instead of
+ * an exception.
+ */
+static inline int copy_kernel_to_xregs_err(struct xregs_state *xstate, u64 mask)
+{
+ u32 lmask = mask;
+ u32 hmask = mask >> 32;
+ int err;
+
+ if (static_cpu_has(X86_FEATURE_XSAVES))
+ XSTATE_OP(XRSTORS, xstate, lmask, hmask, err);
+ else
+ XSTATE_OP(XRSTOR, xstate, lmask, hmask, err);
+
+ return err;
+}
+
+extern int copy_fpregs_to_fpstate(struct fpu *fpu);
+
+static inline void __copy_kernel_to_fpregs(union fpregs_state *fpstate, u64 mask)
+{
+ if (use_xsave()) {
+ copy_kernel_to_xregs(&fpstate->xsave, mask);
+ } else {
+ if (use_fxsr())
+ copy_kernel_to_fxregs(&fpstate->fxsave);
+ else
+ copy_kernel_to_fregs(&fpstate->fsave);
+ }
+}
+
+static inline void copy_kernel_to_fpregs(union fpregs_state *fpstate)
+{
+ /*
+ * AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception is
+ * pending. Clear the x87 state here by setting it to fixed values.
+ * "m" is a random variable that should be in L1.
+ */
+ if (unlikely(static_cpu_has_bug(X86_BUG_FXSAVE_LEAK))) {
+ asm volatile(
+ "fnclex\n\t"
+ "emms\n\t"
+ "fildl %P[addr]" /* set F?P to defined value */
+ : : [addr] "m" (fpstate));
+ }
+
+ __copy_kernel_to_fpregs(fpstate, -1);
+}
+
+extern int copy_fpstate_to_sigframe(void __user *buf, void __user *fp, int size);
+
+/*
+ * FPU context switch related helper methods:
+ */
+
+DECLARE_PER_CPU(struct fpu *, fpu_fpregs_owner_ctx);
+
+/*
+ * The in-register FPU state for an FPU context on a CPU is assumed to be
+ * valid if the fpu->last_cpu matches the CPU, and the fpu_fpregs_owner_ctx
+ * matches the FPU.
+ *
+ * If the FPU register state is valid, the kernel can skip restoring the
+ * FPU state from memory.
+ *
+ * Any code that clobbers the FPU registers or updates the in-memory
+ * FPU state for a task MUST let the rest of the kernel know that the
+ * FPU registers are no longer valid for this task.
+ *
+ * Either one of these invalidation functions is enough. Invalidate
+ * a resource you control: CPU if using the CPU for something else
+ * (with preemption disabled), FPU for the current task, or a task that
+ * is prevented from running by the current task.
+ */
+static inline void __cpu_invalidate_fpregs_state(void)
+{
+ __this_cpu_write(fpu_fpregs_owner_ctx, NULL);
+}
+
+static inline void __fpu_invalidate_fpregs_state(struct fpu *fpu)
+{
+ fpu->last_cpu = -1;
+}
+
+static inline int fpregs_state_valid(struct fpu *fpu, unsigned int cpu)
+{
+ return fpu == this_cpu_read(fpu_fpregs_owner_ctx) && cpu == fpu->last_cpu;
+}
+
+/*
+ * These generally need preemption protection to work,
+ * do try to avoid using these on their own:
+ */
+static inline void fpregs_deactivate(struct fpu *fpu)
+{
+ this_cpu_write(fpu_fpregs_owner_ctx, NULL);
+ trace_x86_fpu_regs_deactivated(fpu);
+}
+
+static inline void fpregs_activate(struct fpu *fpu)
+{
+ this_cpu_write(fpu_fpregs_owner_ctx, fpu);
+ trace_x86_fpu_regs_activated(fpu);
+}
+
+/*
+ * Internal helper, do not use directly. Use switch_fpu_return() instead.
+ */
+static inline void __fpregs_load_activate(void)
+{
+ struct fpu *fpu = &current->thread.fpu;
+ int cpu = smp_processor_id();
+
+ if (WARN_ON_ONCE(current->flags & PF_KTHREAD))
+ return;
+
+ if (!fpregs_state_valid(fpu, cpu)) {
+ copy_kernel_to_fpregs(&fpu->state);
+ fpregs_activate(fpu);
+ fpu->last_cpu = cpu;
+ }
+ clear_thread_flag(TIF_NEED_FPU_LOAD);
+}
+
+/*
+ * FPU state switching for scheduling.
+ *
+ * This is a two-stage process:
+ *
+ * - switch_fpu_prepare() saves the old state.
+ * This is done within the context of the old process.
+ *
+ * - switch_fpu_finish() sets TIF_NEED_FPU_LOAD; the floating point state
+ * will get loaded on return to userspace, or when the kernel needs it.
+ *
+ * If TIF_NEED_FPU_LOAD is cleared then the CPU's FPU registers
+ * are saved in the current thread's FPU register state.
+ *
+ * If TIF_NEED_FPU_LOAD is set then CPU's FPU registers may not
+ * hold current()'s FPU registers. It is required to load the
+ * registers before returning to userland or using the content
+ * otherwise.
+ *
+ * The FPU context is only stored/restored for a user task and
+ * PF_KTHREAD is used to distinguish between kernel and user threads.
+ */
+static inline void switch_fpu_prepare(struct task_struct *prev, int cpu)
+{
+ struct fpu *old_fpu = &prev->thread.fpu;
+
+ if (static_cpu_has(X86_FEATURE_FPU) && !(prev->flags & PF_KTHREAD)) {
+ if (!copy_fpregs_to_fpstate(old_fpu))
+ old_fpu->last_cpu = -1;
+ else
+ old_fpu->last_cpu = cpu;
+
+ /* But leave fpu_fpregs_owner_ctx! */
+ trace_x86_fpu_regs_deactivated(old_fpu);
+ }
+}
+
+/*
+ * Misc helper functions:
+ */
+
+/*
+ * Load PKRU from the FPU context if available. Delay loading of the
+ * complete FPU state until the return to userland.
+ */
+static inline void switch_fpu_finish(struct task_struct *next)
+{
+ u32 pkru_val = init_pkru_value;
+ struct pkru_state *pk;
+ struct fpu *next_fpu = &next->thread.fpu;
+
+ if (!static_cpu_has(X86_FEATURE_FPU))
+ return;
+
+ set_thread_flag(TIF_NEED_FPU_LOAD);
+
+ if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
+ return;
+
+ /*
+ * PKRU state is switched eagerly because it needs to be valid before we
+ * return to userland e.g. for a copy_to_user() operation.
+ */
+ if (!(next->flags & PF_KTHREAD)) {
+ /*
+ * If the PKRU bit in xsave.header.xfeatures is not set,
+ * then the PKRU component was in init state, which means
+ * XRSTOR will set PKRU to 0. If the bit is not set then
+ * get_xsave_addr() will return NULL because the PKRU value
+ * in memory is not valid. This means pkru_val has to be
+ * set to 0 and not to init_pkru_value.
+ */
+ pk = get_xsave_addr(&next_fpu->state.xsave, XFEATURE_PKRU);
+ pkru_val = pk ? pk->pkru : 0;
+ }
+ __write_pkru(pkru_val);
+}
+
+#endif /* _ASM_X86_FPU_INTERNAL_H */
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-13 15:04:52 +0000