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Date: Mon, 11 Jan 2016 16:00:38 +0100
From: Ingo Molnar <mingo@...nel.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
"H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
Andrew Morton <akpm@...ux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: [GIT PULL] x86/fpu changes for v4.5
Linus,
Please pull the latest x86-fpu-for-linus git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-fpu-for-linus
# HEAD: e49a449b869afb2b8bf282427c8355bc3a2fad56 x86/fpu: Put a few variables in .init.data
This tree cleans up the FPU fault handling methods to be more robust, and moves
eligible variables to .init.data.
Thanks,
Ingo
------------------>
Borislav Petkov (2):
x86/fpu: Add an XSTATE_OP() macro
x86/fpu: Get rid of xstate_fault()
Rasmus Villemoes (1):
x86/fpu: Put a few variables in .init.data
arch/x86/include/asm/fpu/internal.h | 173 +++++++++++++++++-------------------
arch/x86/kernel/fpu/init.c | 4 +-
arch/x86/kernel/fpu/xstate.c | 4 +-
3 files changed, 87 insertions(+), 94 deletions(-)
diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 3c3550c3a4a3..eadcdd5bb946 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -224,18 +224,67 @@ static inline void copy_fxregs_to_kernel(struct fpu *fpu)
#define XRSTOR ".byte " REX_PREFIX "0x0f,0xae,0x2f"
#define XRSTORS ".byte " REX_PREFIX "0x0f,0xc7,0x1f"
-/* xstate instruction fault handler: */
-#define xstate_fault(__err) \
- \
- ".section .fixup,\"ax\"\n" \
- \
- "3: movl $-2,%[_err]\n" \
- " jmp 2b\n" \
- \
- ".previous\n" \
- \
- _ASM_EXTABLE(1b, 3b) \
- : [_err] "=r" (__err)
+#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: movl $-2,%[err]\n\t" \
+ "jmp 2b\n\t" \
+ ".popsection\n\t" \
+ _ASM_EXTABLE(1b, 3b) \
+ : [err] "=r" (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, err) \
+ asm volatile(ALTERNATIVE(XRSTOR, \
+ XRSTORS, 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")
/*
* This function is called only during boot time when x86 caps are not set
@@ -246,22 +295,14 @@ static inline void copy_xregs_to_kernel_booting(struct xregs_state *xstate)
u64 mask = -1;
u32 lmask = mask;
u32 hmask = mask >> 32;
- int err = 0;
+ int err;
WARN_ON(system_state != SYSTEM_BOOTING);
- if (boot_cpu_has(X86_FEATURE_XSAVES))
- asm volatile("1:"XSAVES"\n\t"
- "2:\n\t"
- xstate_fault(err)
- : "D" (xstate), "m" (*xstate), "a" (lmask), "d" (hmask), "0" (err)
- : "memory");
+ if (static_cpu_has_safe(X86_FEATURE_XSAVES))
+ XSTATE_OP(XSAVES, xstate, lmask, hmask, err);
else
- asm volatile("1:"XSAVE"\n\t"
- "2:\n\t"
- xstate_fault(err)
- : "D" (xstate), "m" (*xstate), "a" (lmask), "d" (hmask), "0" (err)
- : "memory");
+ XSTATE_OP(XSAVE, xstate, lmask, hmask, err);
/* We should never fault when copying to a kernel buffer: */
WARN_ON_FPU(err);
@@ -276,22 +317,14 @@ static inline void copy_kernel_to_xregs_booting(struct xregs_state *xstate)
u64 mask = -1;
u32 lmask = mask;
u32 hmask = mask >> 32;
- int err = 0;
+ int err;
WARN_ON(system_state != SYSTEM_BOOTING);
- if (boot_cpu_has(X86_FEATURE_XSAVES))
- asm volatile("1:"XRSTORS"\n\t"
- "2:\n\t"
- xstate_fault(err)
- : "D" (xstate), "m" (*xstate), "a" (lmask), "d" (hmask), "0" (err)
- : "memory");
+ if (static_cpu_has_safe(X86_FEATURE_XSAVES))
+ XSTATE_OP(XRSTORS, xstate, lmask, hmask, err);
else
- asm volatile("1:"XRSTOR"\n\t"
- "2:\n\t"
- xstate_fault(err)
- : "D" (xstate), "m" (*xstate), "a" (lmask), "d" (hmask), "0" (err)
- : "memory");
+ XSTATE_OP(XRSTOR, xstate, lmask, hmask, err);
/* We should never fault when copying from a kernel buffer: */
WARN_ON_FPU(err);
@@ -305,33 +338,11 @@ static inline void copy_xregs_to_kernel(struct xregs_state *xstate)
u64 mask = -1;
u32 lmask = mask;
u32 hmask = mask >> 32;
- int err = 0;
+ int err;
WARN_ON(!alternatives_patched);
- /*
- * If xsaves is enabled, xsaves replaces xsaveopt because
- * it supports 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.
- *
- * If none of xsaves and xsaveopt is enabled, use xsave.
- */
- alternative_input_2(
- "1:"XSAVE,
- XSAVEOPT,
- X86_FEATURE_XSAVEOPT,
- XSAVES,
- X86_FEATURE_XSAVES,
- [xstate] "D" (xstate), "a" (lmask), "d" (hmask) :
- "memory");
- asm volatile("2:\n\t"
- xstate_fault(err)
- : "0" (err)
- : "memory");
+ XSTATE_XSAVE(xstate, lmask, hmask, err);
/* We should never fault when copying to a kernel buffer: */
WARN_ON_FPU(err);
@@ -344,23 +355,9 @@ static inline void copy_kernel_to_xregs(struct xregs_state *xstate, u64 mask)
{
u32 lmask = mask;
u32 hmask = mask >> 32;
- int err = 0;
+ int err;
- /*
- * Use xrstors to restore context if it is enabled. xrstors supports
- * compacted format of xsave area which is not supported by xrstor.
- */
- alternative_input(
- "1: " XRSTOR,
- XRSTORS,
- X86_FEATURE_XSAVES,
- "D" (xstate), "m" (*xstate), "a" (lmask), "d" (hmask)
- : "memory");
-
- asm volatile("2:\n"
- xstate_fault(err)
- : "0" (err)
- : "memory");
+ XSTATE_XRESTORE(xstate, lmask, hmask, err);
/* We should never fault when copying from a kernel buffer: */
WARN_ON_FPU(err);
@@ -388,12 +385,10 @@ static inline int copy_xregs_to_user(struct xregs_state __user *buf)
if (unlikely(err))
return -EFAULT;
- __asm__ __volatile__(ASM_STAC "\n"
- "1:"XSAVE"\n"
- "2: " ASM_CLAC "\n"
- xstate_fault(err)
- : "D" (buf), "a" (-1), "d" (-1), "0" (err)
- : "memory");
+ stac();
+ XSTATE_OP(XSAVE, buf, -1, -1, err);
+ clac();
+
return err;
}
@@ -405,14 +400,12 @@ 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 = 0;
-
- __asm__ __volatile__(ASM_STAC "\n"
- "1:"XRSTOR"\n"
- "2: " ASM_CLAC "\n"
- xstate_fault(err)
- : "D" (xstate), "a" (lmask), "d" (hmask), "0" (err)
- : "memory"); /* memory required? */
+ int err;
+
+ stac();
+ XSTATE_OP(XRSTOR, xstate, lmask, hmask, err);
+ clac();
+
return err;
}
diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index be39b5fde4b9..e1ed5194c02a 100644
--- a/arch/x86/kernel/fpu/init.c
+++ b/arch/x86/kernel/fpu/init.c
@@ -188,7 +188,7 @@ static void __init fpu__init_task_struct_size(void)
*/
static void __init fpu__init_system_xstate_size_legacy(void)
{
- static int on_boot_cpu = 1;
+ static int on_boot_cpu __initdata = 1;
WARN_ON_FPU(!on_boot_cpu);
on_boot_cpu = 0;
@@ -278,7 +278,7 @@ __setup("eagerfpu=", eager_fpu_setup);
*/
static void __init fpu__init_system_ctx_switch(void)
{
- static bool on_boot_cpu = 1;
+ static bool on_boot_cpu __initdata = 1;
WARN_ON_FPU(!on_boot_cpu);
on_boot_cpu = 0;
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 70fc312221fc..40f100285984 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -297,7 +297,7 @@ static void __init setup_xstate_comp(void)
*/
static void __init setup_init_fpu_buf(void)
{
- static int on_boot_cpu = 1;
+ static int on_boot_cpu __initdata = 1;
WARN_ON_FPU(!on_boot_cpu);
on_boot_cpu = 0;
@@ -608,7 +608,7 @@ static void fpu__init_disable_system_xstate(void)
void __init fpu__init_system_xstate(void)
{
unsigned int eax, ebx, ecx, edx;
- static int on_boot_cpu = 1;
+ static int on_boot_cpu __initdata = 1;
int err;
WARN_ON_FPU(!on_boot_cpu);
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