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>
diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index cb33909..b627746 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -131,7 +131,7 @@
* xsave_init().
*/
- if (!HAVE_HWFP) {
+ if (!cpu_has_fpu) {
/*
* Disable xsave as we do not support it if i387
* emulation is enabled.
@@ -158,6 +158,14 @@
unsigned long cr0;
unsigned long cr4_mask = 0;
+#ifndef CONFIG_MATH_EMULATION
+ if (!cpu_has_fpu) {
+ pr_emerg("No FPU found and no math emulation present\n");
+ pr_emerg("Giving up\n");
+ for (;;)
+ asm volatile("hlt");
+ }
+#endif
if (cpu_has_fxsr)
cr4_mask |= X86_CR4_OSFXSR;
if (cpu_has_xmm)
@@ -167,7 +175,7 @@
cr0 = read_cr0();
cr0 &= ~(X86_CR0_TS|X86_CR0_EM); /* clear TS and EM */
- if (!HAVE_HWFP)
+ if (!cpu_has_fpu)
cr0 |= X86_CR0_EM;
write_cr0(cr0);
@@ -185,7 +193,7 @@
void fpu_finit(struct fpu *fpu)
{
- if (!HAVE_HWFP) {
+ if (!cpu_has_fpu) {
finit_soft_fpu(&fpu->state->soft);
return;
}
@@ -214,7 +222,7 @@
int ret;
if (tsk_used_math(tsk)) {
- if (HAVE_HWFP && tsk == current)
+ if (cpu_has_fpu && tsk == current)
unlazy_fpu(tsk);
tsk->thread.fpu.last_cpu = ~0;
return 0;
@@ -511,14 +519,13 @@
if (ret)
return ret;
- if (!HAVE_HWFP)
+ if (!static_cpu_has(X86_FEATURE_FPU))
return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);
- if (!cpu_has_fxsr) {
+ if (!cpu_has_fxsr)
return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
&target->thread.fpu.state->fsave, 0,
-1);
- }
sanitize_i387_state(target);
@@ -545,13 +552,13 @@
sanitize_i387_state(target);
- if (!HAVE_HWFP)
+ if (!static_cpu_has(X86_FEATURE_FPU))
return fpregs_soft_set(target, regset, pos, count, kbuf, ubuf);
- if (!cpu_has_fxsr) {
+ if (!cpu_has_fxsr)
return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
- &target->thread.fpu.state->fsave, 0, -1);
- }
+ &target->thread.fpu.state->fsave, 0,
+ -1);
if (pos > 0 || count < sizeof(env))
convert_from_fxsr(&env, target);
@@ -592,3 +599,33 @@
EXPORT_SYMBOL(dump_fpu);
#endif /* CONFIG_X86_32 || CONFIG_IA32_EMULATION */
+
+static int __init no_387(char *s)
+{
+ setup_clear_cpu_cap(X86_FEATURE_FPU);
+ return 1;
+}
+
+__setup("no387", no_387);
+
+void __cpuinit fpu_detect(struct cpuinfo_x86 *c)
+{
+ unsigned long cr0;
+ u16 fsw, fcw;
+
+ fsw = fcw = 0xffff;
+
+ cr0 = read_cr0();
+ cr0 &= ~(X86_CR0_TS | X86_CR0_EM);
+ write_cr0(cr0);
+
+ asm volatile("fninit ; fnstsw %0 ; fnstcw %1"
+ : "+m" (fsw), "+m" (fcw));
+
+ if (fsw == 0 && (fcw & 0x103f) == 0x003f)
+ set_cpu_cap(c, X86_FEATURE_FPU);
+ else
+ clear_cpu_cap(c, X86_FEATURE_FPU);
+
+ /* The final cr0 value is set in fpu_init() */
+}