From 60e019eb37a8d989031ad47ae9810453536f3127 Mon Sep 17 00:00:00 2001 From: H. Peter Anvin Date: Mon, 29 Apr 2013 16:04:20 +0200 Subject: 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 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 Signed-off-by: H. Peter Anvin --- arch/x86/kernel/i387.c | 59 ++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 48 insertions(+), 11 deletions(-) (limited to 'arch/x86/kernel/i387.c') diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c index cb339097b9ea..b627746f6b1a 100644 --- a/arch/x86/kernel/i387.c +++ b/arch/x86/kernel/i387.c @@ -131,7 +131,7 @@ static void __cpuinit init_thread_xstate(void) * 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 @@ void __cpuinit fpu_init(void) 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 @@ void __cpuinit fpu_init(void) 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 __cpuinit fpu_init(void) 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 init_fpu(struct task_struct *tsk) 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 @@ int fpregs_get(struct task_struct *target, const struct user_regset *regset, 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 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset, 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 @@ int dump_fpu(struct pt_regs *regs, struct user_i387_struct *fpu) 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() */ +} -- cgit v1.2.3