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Subject[tip: x86/fpu] x86/fpu: Move os_xsave() and os_xrstor() to core
The following commit has been merged into the x86/fpu branch of tip:

Commit-ID: df95b0f1aa56dfa71a0ef657e3e62294ee6d9034
Gitweb: https://git.kernel.org/tip/df95b0f1aa56dfa71a0ef657e3e62294ee6d9034
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Fri, 15 Oct 2021 03:16:24 +02:00
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Wed, 20 Oct 2021 15:27:28 +02:00

x86/fpu: Move os_xsave() and os_xrstor() to core

Nothing outside the core code needs these.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211015011539.513368075@linutronix.de
---
arch/x86/include/asm/fpu/internal.h | 165 +--------------------------
arch/x86/include/asm/fpu/xstate.h | 6 +-
arch/x86/kernel/fpu/signal.c | 1 +-
arch/x86/kernel/fpu/xstate.h | 174 +++++++++++++++++++++++++++-
4 files changed, 175 insertions(+), 171 deletions(-)

diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 3ad2ae7..b68f994 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -161,171 +161,6 @@ static inline void fxsave(struct fxregs_state *fx)
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 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 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_TYPE(661b, 3b, EX_TYPE_FPU_RESTORE) \
- : \
- : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \
- : "memory")
-
-/*
- * 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 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.
- *
- * Uses XRSTORS when XSAVES is used, XRSTOR otherwise.
- */
-static inline void os_xrstor(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 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.
- */
- u64 mask = xfeatures_mask_uabi();
- u32 lmask = mask;
- u32 hmask = mask >> 32;
- int err;
-
- 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;
-
- 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 xregs_state *xstate, u64 mask)
-{
- u32 lmask = mask;
- u32 hmask = mask >> 32;
- int err;
-
- if (cpu_feature_enabled(X86_FEATURE_XSAVES))
- XSTATE_OP(XRSTORS, xstate, lmask, hmask, err);
- else
- XSTATE_OP(XRSTOR, xstate, lmask, hmask, err);
-
- return err;
-}
-
extern void restore_fpregs_from_fpstate(union fpregs_state *fpstate, u64 mask);

extern bool copy_fpstate_to_sigframe(void __user *buf, void __user *fp, int size);
diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h
index 109dfcc..b8cebc0 100644
--- a/arch/x86/include/asm/fpu/xstate.h
+++ b/arch/x86/include/asm/fpu/xstate.h
@@ -78,12 +78,6 @@
XFEATURE_MASK_INDEPENDENT | \
XFEATURE_MASK_SUPERVISOR_UNSUPPORTED)

-#ifdef CONFIG_X86_64
-#define REX_PREFIX "0x48, "
-#else
-#define REX_PREFIX
-#endif
-
extern u64 xfeatures_mask_all;

static inline u64 xfeatures_mask_supervisor(void)
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index 2a4d1d0..3b38c59 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -17,6 +17,7 @@
#include <asm/trace/fpu.h>

#include "internal.h"
+#include "xstate.h"

static struct _fpx_sw_bytes fx_sw_reserved __ro_after_init;
static struct _fpx_sw_bytes fx_sw_reserved_ia32 __ro_after_init;
diff --git a/arch/x86/kernel/fpu/xstate.h b/arch/x86/kernel/fpu/xstate.h
index 81f4202..ae61baa 100644
--- a/arch/x86/kernel/fpu/xstate.h
+++ b/arch/x86/kernel/fpu/xstate.h
@@ -18,4 +18,178 @@ static inline void xstate_init_xcomp_bv(struct xregs_state *xsave, u64 mask)
extern void __copy_xstate_to_uabi_buf(struct membuf to, struct xregs_state *xsave,
u32 pkru_val, enum xstate_copy_mode copy_mode);

+/* 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 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 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_TYPE(661b, 3b, EX_TYPE_FPU_RESTORE) \
+ : \
+ : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \
+ : "memory")
+
+/*
+ * 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 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.
+ *
+ * Uses XRSTORS when XSAVES is used, XRSTOR otherwise.
+ */
+static inline void os_xrstor(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 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.
+ */
+ u64 mask = xfeatures_mask_uabi();
+ u32 lmask = mask;
+ u32 hmask = mask >> 32;
+ int err;
+
+ 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;
+
+ 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 xregs_state *xstate, u64 mask)
+{
+ u32 lmask = mask;
+ u32 hmask = mask >> 32;
+ int err;
+
+ 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
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