commit 60e019eb37a8d989031ad47ae9810453536f3127
author H. Peter Anvin <hpa@zytor.com> Mon Apr 29 16:04:20 2013 +0200
committer H. Peter Anvin <hpa@linux.intel.com> Thu Jun 06 14:32:04 2013 -0700
tree c9db47f4c97862b46a2a1481d35e89ee9358ed6a
parent d683b96b072dc4680fc74964eca77e6a23d1fa6e

x86: Get rid of ->hard_math and all the FPU asm fu

Reimplement FPU detection code in C and drop old, not-so-recommended
detection method in asm. Move all the relevant stuff into i387.c where
it conceptually belongs. Finally drop cpuinfo_x86.hard_math.

[ hpa: huge thanks to Borislav for taking my original concept patch
  and productizing it ]

[ Boris, note to self: do not use static_cpu_has before alternatives! ]

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1367244262-29511-2-git-send-email-bp@alien8.de
Link: http://lkml.kernel.org/r/1365436666-9837-2-git-send-email-bp@alien8.de
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/kernel/cpu/bugs.c

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 4112be9..0344534 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -17,15 +17,6 @@
 #include <asm/paravirt.h>
 #include <asm/alternative.h>
 
-static int __init no_387(char *s)
-{
-	boot_cpu_data.hard_math = 0;
-	write_cr0(X86_CR0_TS | X86_CR0_EM | X86_CR0_MP | read_cr0());
-	return 1;
-}
-
-__setup("no387", no_387);
-
 static double __initdata x = 4195835.0;
 static double __initdata y = 3145727.0;
 
@@ -44,15 +35,6 @@
 {
 	s32 fdiv_bug;
 
-	if (!boot_cpu_data.hard_math) {
-#ifndef CONFIG_MATH_EMULATION
-		pr_emerg("No coprocessor found and no math emulation present\n");
-		pr_emerg("Giving up\n");
-		for (;;) ;
-#endif
-		return;
-	}
-
 	kernel_fpu_begin();
 
 	/*
@@ -107,5 +89,6 @@
 	 * kernel_fpu_begin/end() in check_fpu() relies on the patched
 	 * alternative instructions.
 	 */
-	check_fpu();
+	if (cpu_has_fpu)
+		check_fpu();
 }

arch/x86/kernel/cpu/common.c

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 22018f7..d4dd993 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -711,10 +711,9 @@
 		return;
 
 	cpu_detect(c);
-
 	get_cpu_vendor(c);
-
 	get_cpu_cap(c);
+	fpu_detect(c);
 
 	if (this_cpu->c_early_init)
 		this_cpu->c_early_init(c);

arch/x86/kernel/cpu/cyrix.c

diff --git a/arch/x86/kernel/cpu/cyrix.c b/arch/x86/kernel/cpu/cyrix.c
index d048d5c..7582f47 100644
--- a/arch/x86/kernel/cpu/cyrix.c
+++ b/arch/x86/kernel/cpu/cyrix.c
@@ -333,7 +333,7 @@
 		switch (dir0_lsn) {
 		case 0xd:  /* either a 486SLC or DLC w/o DEVID */
 			dir0_msn = 0;
-			p = Cx486_name[(c->hard_math) ? 1 : 0];
+			p = Cx486_name[(cpu_has_fpu ? 1 : 0)];
 			break;
 
 		case 0xe:  /* a 486S A step */

arch/x86/kernel/cpu/proc.c

diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
index 37a198b..aee6317 100644
--- a/arch/x86/kernel/cpu/proc.c
+++ b/arch/x86/kernel/cpu/proc.c
@@ -37,8 +37,8 @@
 		   static_cpu_has_bug(X86_BUG_FDIV) ? "yes" : "no",
 		   static_cpu_has_bug(X86_BUG_F00F) ? "yes" : "no",
 		   static_cpu_has_bug(X86_BUG_COMA) ? "yes" : "no",
-		   c->hard_math ? "yes" : "no",
-		   c->hard_math ? "yes" : "no",
+		   static_cpu_has(X86_FEATURE_FPU) ? "yes" : "no",
+		   static_cpu_has(X86_FEATURE_FPU) ? "yes" : "no",
 		   c->cpuid_level,
 		   c->wp_works_ok ? "yes" : "no");
 }