Commit d652df0b authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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
parents 4d6f843a 5f8c4218
......@@ -303,4 +303,14 @@ config DEBUG_NMI_SELFTEST
If unsure, say N.
config X86_DEBUG_STATIC_CPU_HAS
bool "Debug alternatives"
depends on DEBUG_KERNEL
---help---
This option causes additional code to be generated which
fails if static_cpu_has() is used before alternatives have
run.
If unsure, say N.
endmenu
......@@ -92,7 +92,7 @@
#define X86_FEATURE_LFENCE_RDTSC (3*32+18) /* "" Lfence synchronizes RDTSC */
#define X86_FEATURE_11AP (3*32+19) /* "" Bad local APIC aka 11AP */
#define X86_FEATURE_NOPL (3*32+20) /* The NOPL (0F 1F) instructions */
/* 21 available, was AMD_C1E */
#define X86_FEATURE_ALWAYS (3*32+21) /* "" Always-present feature */
#define X86_FEATURE_XTOPOLOGY (3*32+22) /* cpu topology enum extensions */
#define X86_FEATURE_TSC_RELIABLE (3*32+23) /* TSC is known to be reliable */
#define X86_FEATURE_NONSTOP_TSC (3*32+24) /* TSC does not stop in C states */
......@@ -356,15 +356,36 @@ extern const char * const x86_power_flags[32];
#endif /* CONFIG_X86_64 */
#if __GNUC__ >= 4
extern void warn_pre_alternatives(void);
extern bool __static_cpu_has_safe(u16 bit);
/*
* Static testing of CPU features. Used the same as boot_cpu_has().
* These are only valid after alternatives have run, but will statically
* patch the target code for additional performance.
*
*/
static __always_inline __pure bool __static_cpu_has(u16 bit)
{
#if __GNUC__ > 4 || __GNUC_MINOR__ >= 5
#ifdef CONFIG_X86_DEBUG_STATIC_CPU_HAS
/*
* Catch too early usage of this before alternatives
* have run.
*/
asm goto("1: jmp %l[t_warn]\n"
"2:\n"
".section .altinstructions,\"a\"\n"
" .long 1b - .\n"
" .long 0\n" /* no replacement */
" .word %P0\n" /* 1: do replace */
" .byte 2b - 1b\n" /* source len */
" .byte 0\n" /* replacement len */
".previous\n"
/* skipping size check since replacement size = 0 */
: : "i" (X86_FEATURE_ALWAYS) : : t_warn);
#endif
asm goto("1: jmp %l[t_no]\n"
"2:\n"
".section .altinstructions,\"a\"\n"
......@@ -379,7 +400,13 @@ static __always_inline __pure bool __static_cpu_has(u16 bit)
return true;
t_no:
return false;
#else
#ifdef CONFIG_X86_DEBUG_STATIC_CPU_HAS
t_warn:
warn_pre_alternatives();
return false;
#endif
#else /* GCC_VERSION >= 40500 */
u8 flag;
/* Open-coded due to __stringify() in ALTERNATIVE() */
asm volatile("1: movb $0,%0\n"
......@@ -411,11 +438,94 @@ static __always_inline __pure bool __static_cpu_has(u16 bit)
__static_cpu_has(bit) : \
boot_cpu_has(bit) \
)
static __always_inline __pure bool _static_cpu_has_safe(u16 bit)
{
#if __GNUC__ > 4 || __GNUC_MINOR__ >= 5
/*
* We need to spell the jumps to the compiler because, depending on the offset,
* the replacement jump can be bigger than the original jump, and this we cannot
* have. Thus, we force the jump to the widest, 4-byte, signed relative
* offset even though the last would often fit in less bytes.
*/
asm goto("1: .byte 0xe9\n .long %l[t_dynamic] - 2f\n"
"2:\n"
".section .altinstructions,\"a\"\n"
" .long 1b - .\n" /* src offset */
" .long 3f - .\n" /* repl offset */
" .word %P1\n" /* always replace */
" .byte 2b - 1b\n" /* src len */
" .byte 4f - 3f\n" /* repl len */
".previous\n"
".section .altinstr_replacement,\"ax\"\n"
"3: .byte 0xe9\n .long %l[t_no] - 2b\n"
"4:\n"
".previous\n"
".section .altinstructions,\"a\"\n"
" .long 1b - .\n" /* src offset */
" .long 0\n" /* no replacement */
" .word %P0\n" /* feature bit */
" .byte 2b - 1b\n" /* src len */
" .byte 0\n" /* repl len */
".previous\n"
: : "i" (bit), "i" (X86_FEATURE_ALWAYS)
: : t_dynamic, t_no);
return true;
t_no:
return false;
t_dynamic:
return __static_cpu_has_safe(bit);
#else /* GCC_VERSION >= 40500 */
u8 flag;
/* Open-coded due to __stringify() in ALTERNATIVE() */
asm volatile("1: movb $2,%0\n"
"2:\n"
".section .altinstructions,\"a\"\n"
" .long 1b - .\n" /* src offset */
" .long 3f - .\n" /* repl offset */
" .word %P2\n" /* always replace */
" .byte 2b - 1b\n" /* source len */
" .byte 4f - 3f\n" /* replacement len */
".previous\n"
".section .discard,\"aw\",@progbits\n"
" .byte 0xff + (4f-3f) - (2b-1b)\n" /* size check */
".previous\n"
".section .altinstr_replacement,\"ax\"\n"
"3: movb $0,%0\n"
"4:\n"
".previous\n"
".section .altinstructions,\"a\"\n"
" .long 1b - .\n" /* src offset */
" .long 5f - .\n" /* repl offset */
" .word %P1\n" /* feature bit */
" .byte 4b - 3b\n" /* src len */
" .byte 6f - 5f\n" /* repl len */
".previous\n"
".section .discard,\"aw\",@progbits\n"
" .byte 0xff + (6f-5f) - (4b-3b)\n" /* size check */
".previous\n"
".section .altinstr_replacement,\"ax\"\n"
"5: movb $1,%0\n"
"6:\n"
".previous\n"
: "=qm" (flag)
: "i" (bit), "i" (X86_FEATURE_ALWAYS));
return (flag == 2 ? __static_cpu_has_safe(bit) : flag);
#endif
}
#define static_cpu_has_safe(bit) \
( \
__builtin_constant_p(boot_cpu_has(bit)) ? \
boot_cpu_has(bit) : \
_static_cpu_has_safe(bit) \
)
#else
/*
* gcc 3.x is too stupid to do the static test; fall back to dynamic.
*/
#define static_cpu_has(bit) boot_cpu_has(bit)
#define static_cpu_has(bit) boot_cpu_has(bit)
#define static_cpu_has_safe(bit) boot_cpu_has(bit)
#endif
#define cpu_has_bug(c, bit) cpu_has(c, (bit))
......
......@@ -62,10 +62,8 @@ extern user_regset_set_fn fpregs_set, xfpregs_set, fpregs_soft_set,
#define xstateregs_active fpregs_active
#ifdef CONFIG_MATH_EMULATION
# define HAVE_HWFP (boot_cpu_data.hard_math)
extern void finit_soft_fpu(struct i387_soft_struct *soft);
#else
# define HAVE_HWFP 1
static inline void finit_soft_fpu(struct i387_soft_struct *soft) {}
#endif
......@@ -345,7 +343,7 @@ static inline void __thread_fpu_end(struct task_struct *tsk)
static inline void __thread_fpu_begin(struct task_struct *tsk)
{
if (!use_eager_fpu())
if (!static_cpu_has_safe(X86_FEATURE_EAGER_FPU))
clts();
__thread_set_has_fpu(tsk);
}
......
......@@ -89,9 +89,9 @@ struct cpuinfo_x86 {
char wp_works_ok; /* It doesn't on 386's */
/* Problems on some 486Dx4's and old 386's: */
char hard_math;
char rfu;
char pad0;
char pad1;
#else
/* Number of 4K pages in DTLB/ITLB combined(in pages): */
int x86_tlbsize;
......@@ -164,6 +164,7 @@ extern const struct seq_operations cpuinfo_op;
#define cache_line_size() (boot_cpu_data.x86_cache_alignment)
extern void cpu_detect(struct cpuinfo_x86 *c);
extern void __cpuinit fpu_detect(struct cpuinfo_x86 *c);
extern void early_cpu_init(void);
extern void identify_boot_cpu(void);
......
......@@ -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);
......
......@@ -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();
}
......@@ -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);
......@@ -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 */
......
......@@ -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");
}
......
......@@ -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"
/*
......
......@@ -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() */
}
......@@ -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;
......
......@@ -1410,7 +1410,7 @@ __init void lguest_init(void)
new_cpu_data.x86_capability[0] = cpuid_edx(1);
/* Math is always hard! */
new_cpu_data.hard_math = 1;
set_cpu_cap(&new_cpu_data, X86_FEATURE_FPU);
/* We don't have features. We have puppies! Puppies! */
#ifdef CONFIG_X86_MCE
......
......@@ -1557,7 +1557,7 @@ asmlinkage void __init xen_start_kernel(void)
#ifdef CONFIG_X86_32
/* set up basic CPUID stuff */
cpu_detect(&new_cpu_data);
new_cpu_data.hard_math = 1;
set_cpu_cap(&new_cpu_data, X86_FEATURE_FPU);
new_cpu_data.wp_works_ok = 1;
new_cpu_data.x86_capability[0] = cpuid_edx(1);
#endif
......
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