Make fpu_init() handle 32-bit setup.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
---
 arch/x86/kernel/cpu/common.c |    7 -------
 arch/x86/kernel/i387.c       |   27 ++++++++++++---------------
 arch/x86/kernel/traps.c      |   12 ------------
 3 files changed, 12 insertions(+), 34 deletions(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 490dac6..f9e23e8 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1264,13 +1264,6 @@ void __cpuinit cpu_init(void)
 	clear_all_debug_regs();
 	dbg_restore_debug_regs();
 
-	/*
-	 * Force FPU initialization:
-	 */
-	current_thread_info()->status = 0;
-	clear_used_math();
-	mxcsr_feature_mask_init();
-
 	fpu_init();
 	xsave_init();
 }
diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index a46cb35..c795675 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -80,7 +80,6 @@ static void __cpuinit init_thread_xstate(void)
 #endif
 }
 
-#ifdef CONFIG_X86_64
 /*
  * Called at bootup to set up the initial FPU state that is later cloned
  * into all processes.
@@ -88,12 +87,20 @@ static void __cpuinit init_thread_xstate(void)
 
 void __cpuinit fpu_init(void)
 {
-	unsigned long oldcr0 = read_cr0();
+	unsigned long cr0;
+	unsigned long cr4_mask = 0;
 
-	set_in_cr4(X86_CR4_OSFXSR);
-	set_in_cr4(X86_CR4_OSXMMEXCPT);
+	if (cpu_has_fxsr)
+		cr4_mask |= X86_CR4_OSFXSR;
+	if (cpu_has_xmm)
+		cr4_mask |= X86_CR4_OSXMMEXCPT;
+	set_in_cr4(cr4_mask);
 
-	write_cr0(oldcr0 & ~(X86_CR0_TS|X86_CR0_EM)); /* clear TS and EM */
+	cr0 = read_cr0();
+	cr0 &= ~(X86_CR0_TS|X86_CR0_EM); /* clear TS and EM */
+	if (!HAVE_HWFP)
+		cr0 |= X86_CR0_EM;
+	write_cr0(cr0);
 
 	if (!smp_processor_id())
 		init_thread_xstate();
@@ -104,16 +111,6 @@ void __cpuinit fpu_init(void)
 	clear_used_math();
 }
 
-#else	/* CONFIG_X86_64 */
-
-void __cpuinit fpu_init(void)
-{
-	if (!smp_processor_id())
-		init_thread_xstate();
-}
-
-#endif	/* CONFIG_X86_32 ...
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Is calling set_in_cr4() unconditionally safe for 32-bit CPUs that
don't have cr4? AFAICT, no, because it uses read_cr4().
--

[ message continues ]

Good catch, will fix.
--
Brian Gerst
--

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