[PATCH 4.4.y 004/101] x86/fpu: Add an XSTATE_OP() macro - Linux-stable-mirror

14 Jul 2018

From: Borislav Petkov bp@suse.de
commit b74a0cf1b3db30173eefa00c411775d2b1697700 upstream
Add an XSTATE_OP() macro which contains the XSAVE* fault handling
and replace all non-alternatives users of xstate_fault() with
it.
This fixes also the buglet in copy_xregs_to_user() and
copy_user_to_xregs() where the inline asm didn't have @xstate as
memory reference and thus potentially causing unwanted
reordering of accesses to the extended state.
Signed-off-by: Borislav Petkov bp@suse.de
Cc: Andy Lutomirski luto@amacapital.net
Cc: Borislav Petkov bp@alien8.de
Cc: Brian Gerst brgerst@gmail.com
Cc: Dave Hansen dave.hansen@linux.intel.com
Cc: Denys Vlasenko dvlasenk@redhat.com
Cc: Fenghua Yu fenghua.yu@intel.com
Cc: H. Peter Anvin hpa@zytor.com
Cc: Linus Torvalds torvalds@linux-foundation.org
Cc: Oleg Nesterov oleg@redhat.com
Cc: Peter Zijlstra peterz@infradead.org
Cc: Quentin Casasnovas quentin.casasnovas@oracle.com
Cc: Rik van Riel riel@redhat.com
Cc: Thomas Gleixner tglx@linutronix.de
Link: http://lkml.kernel.org/r/1447932326-4371-2-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar mingo@kernel.org
Signed-off-by: Srivatsa S. Bhat srivatsa@csail.mit.edu
Reviewed-by: Matt Helsley (VMware) matt.helsley@gmail.com
Reviewed-by: Alexey Makhalov amakhalov@vmware.com
Reviewed-by: Bo Gan ganb@vmware.com
---
arch/x86/include/asm/fpu/internal.h |   68 ++++++++++++++++-------------------
 1 file changed, 31 insertions(+), 37 deletions(-)

diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 146d838..839e7b6 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -238,6 +238,20 @@ static inline void copy_fxregs_to_kernel(struct fpu *fpu)
    _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")
+
+
 /*
  * This function is called only during boot time when x86 caps are not set
  * up and alternative can not be used yet.
@@ -247,22 +261,14 @@ 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);
@@ -277,22 +283,14 @@ 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);
@@ -389,12 +387,10 @@ 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;
 }
@@ -406,14 +402,12 @@ 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;
+	int err;
+
+	stac();
+	XSTATE_OP(XRSTOR, xstate, lmask, hmask, err);
+	clac();
-	__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? */
    return err;
 }

    