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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
commit2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch)
tree848558de17fb3008cdf4d861b01ac7781903ce39 /arch/x86/kernel/fpu/xstate.h
parentInitial commit. (diff)
downloadlinux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz
linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/x86/kernel/fpu/xstate.h')
-rw-r--r--arch/x86/kernel/fpu/xstate.h327
1 files changed, 327 insertions, 0 deletions
diff --git a/arch/x86/kernel/fpu/xstate.h b/arch/x86/kernel/fpu/xstate.h
new file mode 100644
index 000000000..3518fb26d
--- /dev/null
+++ b/arch/x86/kernel/fpu/xstate.h
@@ -0,0 +1,327 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __X86_KERNEL_FPU_XSTATE_H
+#define __X86_KERNEL_FPU_XSTATE_H
+
+#include <asm/cpufeature.h>
+#include <asm/fpu/xstate.h>
+#include <asm/fpu/xcr.h>
+
+#ifdef CONFIG_X86_64
+DECLARE_PER_CPU(u64, xfd_state);
+#endif
+
+static inline void xstate_init_xcomp_bv(struct xregs_state *xsave, u64 mask)
+{
+ /*
+ * XRSTORS requires these bits set in xcomp_bv, or it will
+ * trigger #GP:
+ */
+ if (cpu_feature_enabled(X86_FEATURE_XCOMPACTED))
+ xsave->header.xcomp_bv = mask | XCOMP_BV_COMPACTED_FORMAT;
+}
+
+static inline u64 xstate_get_group_perm(bool guest)
+{
+ struct fpu *fpu = &current->group_leader->thread.fpu;
+ struct fpu_state_perm *perm;
+
+ /* Pairs with WRITE_ONCE() in xstate_request_perm() */
+ perm = guest ? &fpu->guest_perm : &fpu->perm;
+ return READ_ONCE(perm->__state_perm);
+}
+
+static inline u64 xstate_get_host_group_perm(void)
+{
+ return xstate_get_group_perm(false);
+}
+
+enum xstate_copy_mode {
+ XSTATE_COPY_FP,
+ XSTATE_COPY_FX,
+ XSTATE_COPY_XSAVE,
+};
+
+struct membuf;
+extern void __copy_xstate_to_uabi_buf(struct membuf to, struct fpstate *fpstate,
+ u64 xfeatures, u32 pkru_val,
+ enum xstate_copy_mode copy_mode);
+extern void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk,
+ enum xstate_copy_mode mode);
+extern int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf, u32 *pkru);
+extern int copy_sigframe_from_user_to_xstate(struct task_struct *tsk, const void __user *ubuf);
+
+
+extern void fpu__init_cpu_xstate(void);
+extern void fpu__init_system_xstate(unsigned int legacy_size);
+
+extern void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr);
+
+static inline u64 xfeatures_mask_supervisor(void)
+{
+ return fpu_kernel_cfg.max_features & XFEATURE_MASK_SUPERVISOR_SUPPORTED;
+}
+
+static inline u64 xfeatures_mask_independent(void)
+{
+ if (!cpu_feature_enabled(X86_FEATURE_ARCH_LBR))
+ return XFEATURE_MASK_INDEPENDENT & ~XFEATURE_MASK_LBR;
+
+ return XFEATURE_MASK_INDEPENDENT;
+}
+
+/* XSAVE/XRSTOR wrapper functions */
+
+#ifdef CONFIG_X86_64
+#define REX_PREFIX "0x48, "
+#else
+#define REX_PREFIX
+#endif
+
+/* 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 XSAVEC ".byte " REX_PREFIX "0x0f,0xc7,0x27"
+#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 trap number when the
+ * operation raises an exception.
+ */
+#define XSTATE_OP(op, st, lmask, hmask, err) \
+ asm volatile("1:" op "\n\t" \
+ "xor %[err], %[err]\n" \
+ "2:\n\t" \
+ _ASM_EXTABLE_TYPE(1b, 2b, EX_TYPE_FAULT_MCE_SAFE) \
+ : [err] "=a" (err) \
+ : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \
+ : "memory")
+
+/*
+ * If XSAVES is enabled, it replaces XSAVEC because it supports supervisor
+ * states in addition to XSAVEC.
+ *
+ * Otherwise if XSAVEC is enabled, it replaces XSAVEOPT because it supports
+ * compacted storage format in addition to 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_3(XSAVE, \
+ XSAVEOPT, X86_FEATURE_XSAVEOPT, \
+ XSAVEC, X86_FEATURE_XSAVEC, \
+ XSAVES, X86_FEATURE_XSAVES) \
+ "\n" \
+ "xor %[err], %[err]\n" \
+ "3:\n" \
+ _ASM_EXTABLE_TYPE_REG(661b, 3b, EX_TYPE_EFAULT_REG, %[err]) \
+ : [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_TYPE(661b, 3b, EX_TYPE_FPU_RESTORE) \
+ : \
+ : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \
+ : "memory")
+
+#if defined(CONFIG_X86_64) && defined(CONFIG_X86_DEBUG_FPU)
+extern void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor);
+#else
+static inline void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor) { }
+#endif
+
+#ifdef CONFIG_X86_64
+static inline void xfd_update_state(struct fpstate *fpstate)
+{
+ if (fpu_state_size_dynamic()) {
+ u64 xfd = fpstate->xfd;
+
+ if (__this_cpu_read(xfd_state) != xfd) {
+ wrmsrl(MSR_IA32_XFD, xfd);
+ __this_cpu_write(xfd_state, xfd);
+ }
+ }
+}
+
+extern int __xfd_enable_feature(u64 which, struct fpu_guest *guest_fpu);
+#else
+static inline void xfd_update_state(struct fpstate *fpstate) { }
+
+static inline int __xfd_enable_feature(u64 which, struct fpu_guest *guest_fpu) {
+ return -EPERM;
+}
+#endif
+
+/*
+ * Save processor xstate to xsave area.
+ *
+ * Uses either XSAVE or XSAVEOPT or XSAVES depending on the CPU features
+ * and command line options. The choice is permanent until the next reboot.
+ */
+static inline void os_xsave(struct fpstate *fpstate)
+{
+ u64 mask = fpstate->xfeatures;
+ u32 lmask = mask;
+ u32 hmask = mask >> 32;
+ int err;
+
+ WARN_ON_FPU(!alternatives_patched);
+ xfd_validate_state(fpstate, mask, false);
+
+ XSTATE_XSAVE(&fpstate->regs.xsave, lmask, hmask, err);
+
+ /* We should never fault when copying to a kernel buffer: */
+ WARN_ON_FPU(err);
+}
+
+/*
+ * Restore processor xstate from xsave area.
+ *
+ * Uses XRSTORS when XSAVES is used, XRSTOR otherwise.
+ */
+static inline void os_xrstor(struct fpstate *fpstate, u64 mask)
+{
+ u32 lmask = mask;
+ u32 hmask = mask >> 32;
+
+ xfd_validate_state(fpstate, mask, true);
+ XSTATE_XRESTORE(&fpstate->regs.xsave, lmask, hmask);
+}
+
+/* Restore of supervisor state. Does not require XFD */
+static inline void os_xrstor_supervisor(struct fpstate *fpstate)
+{
+ u64 mask = xfeatures_mask_supervisor();
+ u32 lmask = mask;
+ u32 hmask = mask >> 32;
+
+ XSTATE_XRESTORE(&fpstate->regs.xsave, lmask, hmask);
+}
+
+/*
+ * XSAVE itself always writes all requested xfeatures. Removing features
+ * from the request bitmap reduces the features which are written.
+ * Generate a mask of features which must be written to a sigframe. The
+ * unset features can be optimized away and not written.
+ *
+ * This optimization is user-visible. Only use for states where
+ * uninitialized sigframe contents are tolerable, like dynamic features.
+ *
+ * Users of buffers produced with this optimization must check XSTATE_BV
+ * to determine which features have been optimized out.
+ */
+static inline u64 xfeatures_need_sigframe_write(void)
+{
+ u64 xfeaures_to_write;
+
+ /* In-use features must be written: */
+ xfeaures_to_write = xfeatures_in_use();
+
+ /* Also write all non-optimizable sigframe features: */
+ xfeaures_to_write |= XFEATURE_MASK_USER_SUPPORTED &
+ ~XFEATURE_MASK_SIGFRAME_INITOPT;
+
+ return xfeaures_to_write;
+}
+
+/*
+ * 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 the compacted format of the
+ * xsave area.
+ *
+ * The caller has to zero buf::header before calling this because XSAVE*
+ * does not touch the reserved fields in the header.
+ */
+static inline int xsave_to_user_sigframe(struct xregs_state __user *buf)
+{
+ /*
+ * Include the features which are not xsaved/rstored by the kernel
+ * internally, e.g. PKRU. That's user space ABI and also required
+ * to allow the signal handler to modify PKRU.
+ */
+ struct fpstate *fpstate = current->thread.fpu.fpstate;
+ u64 mask = fpstate->user_xfeatures;
+ u32 lmask;
+ u32 hmask;
+ int err;
+
+ /* Optimize away writing unnecessary xfeatures: */
+ if (fpu_state_size_dynamic())
+ mask &= xfeatures_need_sigframe_write();
+
+ lmask = mask;
+ hmask = mask >> 32;
+ xfd_validate_state(fpstate, mask, false);
+
+ stac();
+ XSTATE_OP(XSAVE, buf, lmask, hmask, err);
+ clac();
+
+ return err;
+}
+
+/*
+ * Restore xstate from user space xsave area.
+ */
+static inline int xrstor_from_user_sigframe(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;
+
+ xfd_validate_state(current->thread.fpu.fpstate, mask, true);
+
+ 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 os_xrstor_safe(struct fpstate *fpstate, u64 mask)
+{
+ struct xregs_state *xstate = &fpstate->regs.xsave;
+ u32 lmask = mask;
+ u32 hmask = mask >> 32;
+ int err;
+
+ /* Ensure that XFD is up to date */
+ xfd_update_state(fpstate);
+
+ if (cpu_feature_enabled(X86_FEATURE_XSAVES))
+ XSTATE_OP(XRSTORS, xstate, lmask, hmask, err);
+ else
+ XSTATE_OP(XRSTOR, xstate, lmask, hmask, err);
+
+ return err;
+}
+
+
+#endif