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authorLinus Torvalds <torvalds@linux-foundation.org>2013-07-02 16:26:44 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-07-02 16:26:44 -0700
commitd652df0b2f0b9c2e655be0d6f90989fae0a511b4 (patch)
treefce939bb45c3d656798d91f7a6dd9d3fbf7189ca /arch/x86/kernel
parent4d6f843a38fa26035598f1f35181aa5f328db897 (diff)
parent5f8c4218148822fde6eebbeefc34bd0a6061e031 (diff)
Merge branch 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 FPU changes from Ingo Molnar: "There are two bigger changes in this tree: - Add an [early-use-]safe static_cpu_has() variant and other robustness improvements, including the new X86_DEBUG_STATIC_CPU_HAS configurable debugging facility, motivated by recent obscure FPU code bugs, by Borislav Petkov - Reimplement FPU detection code in C and drop the old asm code, by Peter Anvin." * 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86, fpu: Use static_cpu_has_safe before alternatives x86: Add a static_cpu_has_safe variant x86: Sanity-check static_cpu_has usage x86, cpu: Add a synthetic, always true, cpu feature x86: Get rid of ->hard_math and all the FPU asm fu
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r--arch/x86/kernel/asm-offsets_32.c1
-rw-r--r--arch/x86/kernel/cpu/bugs.c21
-rw-r--r--arch/x86/kernel/cpu/common.c19
-rw-r--r--arch/x86/kernel/cpu/cyrix.c2
-rw-r--r--arch/x86/kernel/cpu/proc.c4
-rw-r--r--arch/x86/kernel/head_32.S21
-rw-r--r--arch/x86/kernel/i387.c59
-rw-r--r--arch/x86/kernel/xsave.c5
8 files changed, 72 insertions, 60 deletions
diff --git a/arch/x86/kernel/asm-offsets_32.c b/arch/x86/kernel/asm-offsets_32.c
index 0ef4bba2acb7..d67c4be3e8b1 100644
--- a/arch/x86/kernel/asm-offsets_32.c
+++ b/arch/x86/kernel/asm-offsets_32.c
@@ -28,7 +28,6 @@ void foo(void)
OFFSET(CPUINFO_x86_vendor, cpuinfo_x86, x86_vendor);
OFFSET(CPUINFO_x86_model, cpuinfo_x86, x86_model);
OFFSET(CPUINFO_x86_mask, cpuinfo_x86, x86_mask);
- OFFSET(CPUINFO_hard_math, cpuinfo_x86, hard_math);
OFFSET(CPUINFO_cpuid_level, cpuinfo_x86, cpuid_level);
OFFSET(CPUINFO_x86_capability, cpuinfo_x86, x86_capability);
OFFSET(CPUINFO_x86_vendor_id, cpuinfo_x86, x86_vendor_id);
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 4112be9a4659..03445346ee0a 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 @@ static void __init check_fpu(void)
{
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 @@ void __init check_bugs(void)
* kernel_fpu_begin/end() in check_fpu() relies on the patched
* alternative instructions.
*/
- check_fpu();
+ if (cpu_has_fpu)
+ check_fpu();
}
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 22018f70a671..a4a07c0acb1f 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -711,10 +711,9 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
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);
@@ -724,6 +723,8 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
if (this_cpu->c_bsp_init)
this_cpu->c_bsp_init(c);
+
+ setup_force_cpu_cap(X86_FEATURE_ALWAYS);
}
void __init early_cpu_init(void)
@@ -1363,3 +1364,17 @@ void __cpuinit cpu_init(void)
fpu_init();
}
#endif
+
+#ifdef CONFIG_X86_DEBUG_STATIC_CPU_HAS
+void warn_pre_alternatives(void)
+{
+ WARN(1, "You're using static_cpu_has before alternatives have run!\n");
+}
+EXPORT_SYMBOL_GPL(warn_pre_alternatives);
+#endif
+
+inline bool __static_cpu_has_safe(u16 bit)
+{
+ return boot_cpu_has(bit);
+}
+EXPORT_SYMBOL_GPL(__static_cpu_has_safe);
diff --git a/arch/x86/kernel/cpu/cyrix.c b/arch/x86/kernel/cpu/cyrix.c
index d048d5ca43c1..7582f475b163 100644
--- a/arch/x86/kernel/cpu/cyrix.c
+++ b/arch/x86/kernel/cpu/cyrix.c
@@ -333,7 +333,7 @@ static void __cpuinit init_cyrix(struct cpuinfo_x86 *c)
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 */
diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
index 37a198bd48c8..aee6317b902f 100644
--- a/arch/x86/kernel/cpu/proc.c
+++ b/arch/x86/kernel/cpu/proc.c
@@ -37,8 +37,8 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
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");
}
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index 73afd11799ca..e65ddc62e113 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -444,7 +444,6 @@ is486:
orl %ecx,%eax
movl %eax,%cr0
- call check_x87
lgdt early_gdt_descr
lidt idt_descr
ljmp $(__KERNEL_CS),$1f
@@ -467,26 +466,6 @@ is486:
pushl $0 # fake return address for unwinder
jmp *(initial_code)
-/*
- * We depend on ET to be correct. This checks for 287/387.
- */
-check_x87:
- movb $0,X86_HARD_MATH
- clts
- fninit
- fstsw %ax
- cmpb $0,%al
- je 1f
- movl %cr0,%eax /* no coprocessor: have to set bits */
- xorl $4,%eax /* set EM */
- movl %eax,%cr0
- ret
- ALIGN
-1: movb $1,X86_HARD_MATH
- .byte 0xDB,0xE4 /* fsetpm for 287, ignored by 387 */
- ret
-
-
#include "verify_cpu.S"
/*
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() */
+}
diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c
index ada87a329edc..d6c28acdf99c 100644
--- a/arch/x86/kernel/xsave.c
+++ b/arch/x86/kernel/xsave.c
@@ -243,7 +243,7 @@ int save_xstate_sig(void __user *buf, void __user *buf_fx, int size)
if (!access_ok(VERIFY_WRITE, buf, size))
return -EACCES;
- if (!HAVE_HWFP)
+ if (!static_cpu_has(X86_FEATURE_FPU))
return fpregs_soft_get(current, NULL, 0,
sizeof(struct user_i387_ia32_struct), NULL,
(struct _fpstate_ia32 __user *) buf) ? -1 : 1;
@@ -350,11 +350,10 @@ int __restore_xstate_sig(void __user *buf, void __user *buf_fx, int size)
if (!used_math() && init_fpu(tsk))
return -1;
- if (!HAVE_HWFP) {
+ if (!static_cpu_has(X86_FEATURE_FPU))
return fpregs_soft_set(current, NULL,
0, sizeof(struct user_i387_ia32_struct),
NULL, buf) != 0;
- }
if (use_xsave()) {
struct _fpx_sw_bytes fx_sw_user;