x86-32, fpu: Rewrite fpu_save_init()

Rewrite fpu_save_init() to prepare for merging with 64-bit.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <1283563039-3466-12-git-send-email-brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 22 insertions, 25 deletions

diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
index 907967e4fa8d..b45abefb89f2 100644
--- a/arch/x86/include/asm/i387.h
+++ b/arch/x86/include/asm/i387.h
@@ -73,6 +73,11 @@ 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);
+}
+
 extern void __sanitize_i387_state(struct task_struct *);
 
 static inline void sanitize_i387_state(struct task_struct *tsk)
@@ -211,6 +216,12 @@ static inline int fxrstor_checking(struct i387_fxsave_struct *fx)
         return 0;
 }
 
+static inline void fpu_fxsave(struct fpu *fpu)
+{
+        asm volatile("fxsave %[fx]"
+                     : [fx] "=m" (fpu->state->fxsave));
+}
+
 /* We need a safe address that is cheap to find and that is already
    in L1 during context switch. The best choices are unfortunately
    different for UP and SMP */
@@ -226,36 +237,24 @@ static inline int fxrstor_checking(struct i387_fxsave_struct *fx)
 static inline void fpu_save_init(struct fpu *fpu)
 {
         if (use_xsave()) {
-                struct xsave_struct *xstate = &fpu->state->xsave;
-                struct i387_fxsave_struct *fx = &fpu->state->fxsave;
-
                 fpu_xsave(fpu);
 
                 /*
                  * xsave header may indicate the init state of the FP.
                  */
-                if (!(xstate->xsave_hdr.xstate_bv & XSTATE_FP))
-                        goto end;
-
-                if (unlikely(fx->swd & X87_FSW_ES))
-                        asm volatile("fnclex");
-
-                /*
-                 * we can do a simple return here or be paranoid :)
-                 */
-                goto clear_state;
+                if (!(fpu->state->xsave.xsave_hdr.xstate_bv & XSTATE_FP))
+                        return;
+        } else if (use_fxsr()) {
+                fpu_fxsave(fpu);
+        } else {
+                asm volatile("fsave %[fx]; fwait"
+                             : [fx] "=m" (fpu->state->fsave));
+                return;
         }
 
-        /* Use more nops than strictly needed in case the compiler
-           varies code */
-        alternative_input(
-                "fnsave %[fx] ;fwait;" GENERIC_NOP8 GENERIC_NOP4,
-                "fxsave %[fx]\n"
-                "bt $7,%[fsw] ; jnc 1f ; fnclex\n1:",
-                X86_FEATURE_FXSR,
-                [fx] "m" (fpu->state->fxsave),
-                [fsw] "m" (fpu->state->fxsave.swd) : "memory");
-clear_state:
+        if (unlikely(fpu->state->fxsave.swd & X87_FSW_ES))
+                asm volatile("fnclex");
+
         /* 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. safe_address is a random variable that should be in L1 */
@@ -265,8 +264,6 @@ clear_state:
                 "fildl %[addr]",        /* set F?P to defined value */
                 X86_FEATURE_FXSAVE_LEAK,
                 [addr] "m" (safe_address));
-end:
-        ;
 }
 
 #endif  /* CONFIG_X86_64 */