Release 4.14 arch/x86/kernel/fpu/init.c
/*
* x86 FPU boot time init code:
*/
#include <asm/fpu/internal.h>
#include <asm/tlbflush.h>
#include <asm/setup.h>
#include <asm/cmdline.h>
#include <linux/sched.h>
#include <linux/sched/task.h>
#include <linux/init.h>
/*
* Initialize the registers found in all CPUs, CR0 and CR4:
*/
static void fpu__init_cpu_generic(void)
{
unsigned long cr0;
unsigned long cr4_mask = 0;
if (boot_cpu_has(X86_FEATURE_FXSR))
cr4_mask |= X86_CR4_OSFXSR;
if (boot_cpu_has(X86_FEATURE_XMM))
cr4_mask |= X86_CR4_OSXMMEXCPT;
if (cr4_mask)
cr4_set_bits(cr4_mask);
cr0 = read_cr0();
cr0 &= ~(X86_CR0_TS|X86_CR0_EM); /* clear TS and EM */
if (!boot_cpu_has(X86_FEATURE_FPU))
cr0 |= X86_CR0_EM;
write_cr0(cr0);
/* Flush out any pending x87 state: */
#ifdef CONFIG_MATH_EMULATION
if (!boot_cpu_has(X86_FEATURE_FPU))
fpstate_init_soft(¤t->thread.fpu.state.soft);
else
#endif
asm volatile ("fninit");
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Ingo Molnar | 97 | 85.84% | 3 | 50.00% |
| Borislav Petkov | 16 | 14.16% | 3 | 50.00% |
| Total | 113 | 100.00% | 6 | 100.00% |
/*
* Enable all supported FPU features. Called when a CPU is brought online:
*/
void fpu__init_cpu(void)
{
fpu__init_cpu_generic();
fpu__init_cpu_xstate();
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Ingo Molnar | 13 | 100.00% | 1 | 100.00% |
| Total | 13 | 100.00% | 1 | 100.00% |
static bool fpu__probe_without_cpuid(void)
{
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));
pr_info("x86/fpu: Probing for FPU: FSW=0x%04hx FCW=0x%04hx\n", fsw, fcw);
return fsw == 0 && (fcw & 0x103f) == 0x003f;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Ingo Molnar | 38 | 56.72% | 1 | 50.00% |
| Andrew Lutomirski | 29 | 43.28% | 1 | 50.00% |
| Total | 67 | 100.00% | 2 | 100.00% |
static void fpu__init_system_early_generic(struct cpuinfo_x86 *c)
{
if (!boot_cpu_has(X86_FEATURE_CPUID) &&
!test_bit(X86_FEATURE_FPU, (unsigned long *)cpu_caps_cleared)) {
if (fpu__probe_without_cpuid())
setup_force_cpu_cap(X86_FEATURE_FPU);
else
setup_clear_cpu_cap(X86_FEATURE_FPU);
}
#ifndef CONFIG_MATH_EMULATION
if (!test_cpu_cap(&boot_cpu_data, X86_FEATURE_FPU)) {
pr_emerg("x86/fpu: Giving up, no FPU found and no math emulation present\n");
for (;;)
asm volatile("hlt");
}
#endif
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Andrew Lutomirski | 41 | 50.62% | 3 | 42.86% |
| Ingo Molnar | 37 | 45.68% | 3 | 42.86% |
| Borislav Petkov | 3 | 3.70% | 1 | 14.29% |
| Total | 81 | 100.00% | 7 | 100.00% |
/*
* Boot time FPU feature detection code:
*/
unsigned int mxcsr_feature_mask __read_mostly = 0xffffffffu;
EXPORT_SYMBOL_GPL(mxcsr_feature_mask);
static void __init fpu__init_system_mxcsr(void)
{
unsigned int mask = 0;
if (boot_cpu_has(X86_FEATURE_FXSR)) {
/* Static because GCC does not get 16-byte stack alignment right: */
static struct fxregs_state fxregs __initdata;
asm volatile("fxsave %0" : "+m" (fxregs));
mask = fxregs.mxcsr_mask;
/*
* If zero then use the default features mask,
* which has all features set, except the
* denormals-are-zero feature bit:
*/
if (mask == 0)
mask = 0x0000ffbf;
}
mxcsr_feature_mask &= mask;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Ingo Molnar | 51 | 92.73% | 6 | 85.71% |
| Borislav Petkov | 4 | 7.27% | 1 | 14.29% |
| Total | 55 | 100.00% | 7 | 100.00% |
/*
* Once per bootup FPU initialization sequences that will run on most x86 CPUs:
*/
static void __init fpu__init_system_generic(void)
{
/*
* Set up the legacy init FPU context. (xstate init might overwrite this
* with a more modern format, if the CPU supports it.)
*/
fpstate_init(&init_fpstate);
fpu__init_system_mxcsr();
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Ingo Molnar | 18 | 94.74% | 3 | 75.00% |
| Borislav Petkov | 1 | 5.26% | 1 | 25.00% |
| Total | 19 | 100.00% | 4 | 100.00% |
/*
* Size of the FPU context state. All tasks in the system use the
* same context size, regardless of what portion they use.
* This is inherent to the XSAVE architecture which puts all state
* components into a single, continuous memory block:
*/
unsigned int fpu_kernel_xstate_size;
EXPORT_SYMBOL_GPL(fpu_kernel_xstate_size);
/* Get alignment of the TYPE. */
#define TYPE_ALIGN(TYPE) offsetof(struct { char x; TYPE test; }, test)
/*
* Enforce that 'MEMBER' is the last field of 'TYPE'.
*
* Align the computed size with alignment of the TYPE,
* because that's how C aligns structs.
*/
#define CHECK_MEMBER_AT_END_OF(TYPE, MEMBER) \
BUILD_BUG_ON(sizeof(TYPE) != ALIGN(offsetofend(TYPE, MEMBER), \
TYPE_ALIGN(TYPE)))
/*
* We append the 'struct fpu' to the task_struct:
*/
static void __init fpu__init_task_struct_size(void)
{
int task_size = sizeof(struct task_struct);
/*
* Subtract off the static size of the register state.
* It potentially has a bunch of padding.
*/
task_size -= sizeof(((struct task_struct *)0)->thread.fpu.state);
/*
* Add back the dynamically-calculated register state
* size.
*/
task_size += fpu_kernel_xstate_size;
/*
* We dynamically size 'struct fpu', so we require that
* it be at the end of 'thread_struct' and that
* 'thread_struct' be at the end of 'task_struct'. If
* you hit a compile error here, check the structure to
* see if something got added to the end.
*/
CHECK_MEMBER_AT_END_OF(struct fpu, state);
CHECK_MEMBER_AT_END_OF(struct thread_struct, fpu);
CHECK_MEMBER_AT_END_OF(struct task_struct, thread);
arch_task_struct_size = task_size;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Dave Hansen | 65 | 89.04% | 1 | 33.33% |
| Ingo Molnar | 7 | 9.59% | 1 | 33.33% |
| Fenghua Yu | 1 | 1.37% | 1 | 33.33% |
| Total | 73 | 100.00% | 3 | 100.00% |
/*
* Set up the user and kernel xstate sizes based on the legacy FPU context size.
*
* We set this up first, and later it will be overwritten by
* fpu__init_system_xstate() if the CPU knows about xstates.
*/
static void __init fpu__init_system_xstate_size_legacy(void)
{
static int on_boot_cpu __initdata = 1;
WARN_ON_FPU(!on_boot_cpu);
on_boot_cpu = 0;
/*
* Note that xstate sizes might be overwritten later during
* fpu__init_system_xstate().
*/
if (!boot_cpu_has(X86_FEATURE_FPU)) {
/*
* Disable xsave as we do not support it if i387
* emulation is enabled.
*/
setup_clear_cpu_cap(X86_FEATURE_XSAVE);
setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
fpu_kernel_xstate_size = sizeof(struct swregs_state);
} else {
if (boot_cpu_has(X86_FEATURE_FXSR))
fpu_kernel_xstate_size =
sizeof(struct fxregs_state);
else
fpu_kernel_xstate_size =
sizeof(struct fregs_state);
}
fpu_user_xstate_size = fpu_kernel_xstate_size;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Ingo Molnar | 70 | 80.46% | 6 | 54.55% |
| Borislav Petkov | 8 | 9.20% | 2 | 18.18% |
| Fenghua Yu | 8 | 9.20% | 2 | 18.18% |
| Rasmus Villemoes | 1 | 1.15% | 1 | 9.09% |
| Total | 87 | 100.00% | 11 | 100.00% |
/*
* Find supported xfeatures based on cpu features and command-line input.
* This must be called after fpu__init_parse_early_param() is called and
* xfeatures_mask is enumerated.
*/
u64 __init fpu__get_supported_xfeatures_mask(void)
{
return XCNTXT_MASK;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Yu-cheng Yu | 11 | 100.00% | 1 | 100.00% |
| Total | 11 | 100.00% | 1 | 100.00% |
/* Legacy code to initialize eager fpu mode. */
static void __init fpu__init_system_ctx_switch(void)
{
static bool on_boot_cpu __initdata = 1;
WARN_ON_FPU(!on_boot_cpu);
on_boot_cpu = 0;
WARN_ON_FPU(current->thread.fpu.initialized);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Ingo Molnar | 36 | 97.30% | 6 | 85.71% |
| Rasmus Villemoes | 1 | 2.70% | 1 | 14.29% |
| Total | 37 | 100.00% | 7 | 100.00% |
/*
* We parse fpu parameters early because fpu__init_system() is executed
* before parse_early_param().
*/
static void __init fpu__init_parse_early_param(void)
{
if (cmdline_find_option_bool(boot_command_line, "no387"))
setup_clear_cpu_cap(X86_FEATURE_FPU);
if (cmdline_find_option_bool(boot_command_line, "nofxsr")) {
setup_clear_cpu_cap(X86_FEATURE_FXSR);
setup_clear_cpu_cap(X86_FEATURE_FXSR_OPT);
setup_clear_cpu_cap(X86_FEATURE_XMM);
}
if (cmdline_find_option_bool(boot_command_line, "noxsave"))
fpu__xstate_clear_all_cpu_caps();
if (cmdline_find_option_bool(boot_command_line, "noxsaveopt"))
setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
if (cmdline_find_option_bool(boot_command_line, "noxsaves"))
setup_clear_cpu_cap(X86_FEATURE_XSAVES);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Yu-cheng Yu | 49 | 55.06% | 1 | 12.50% |
| Ingo Molnar | 37 | 41.57% | 5 | 62.50% |
| Dave Hansen | 2 | 2.25% | 1 | 12.50% |
| Jan Beulich | 1 | 1.12% | 1 | 12.50% |
| Total | 89 | 100.00% | 8 | 100.00% |
/*
* Called on the boot CPU once per system bootup, to set up the initial
* FPU state that is later cloned into all processes:
*/
void __init fpu__init_system(struct cpuinfo_x86 *c)
{
fpu__init_parse_early_param();
fpu__init_system_early_generic(c);
/*
* The FPU has to be operational for some of the
* later FPU init activities:
*/
fpu__init_cpu();
fpu__init_system_generic();
fpu__init_system_xstate_size_legacy();
fpu__init_system_xstate();
fpu__init_task_struct_size();
fpu__init_system_ctx_switch();
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Yu-cheng Yu | 27 | 71.05% | 1 | 50.00% |
| Ingo Molnar | 11 | 28.95% | 1 | 50.00% |
| Total | 38 | 100.00% | 2 | 100.00% |
Overall Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Ingo Molnar | 448 | 59.26% | 28 | 60.87% |
| Yu-cheng Yu | 99 | 13.10% | 2 | 4.35% |
| Dave Hansen | 76 | 10.05% | 2 | 4.35% |
| Andrew Lutomirski | 71 | 9.39% | 4 | 8.70% |
| Borislav Petkov | 32 | 4.23% | 4 | 8.70% |
| Fenghua Yu | 12 | 1.59% | 2 | 4.35% |
| Jiri Olsa | 10 | 1.32% | 1 | 2.17% |
| Wanpeng Li | 5 | 0.66% | 1 | 2.17% |
| Rasmus Villemoes | 2 | 0.26% | 1 | 2.17% |
| Jan Beulich | 1 | 0.13% | 1 | 2.17% |
| Total | 756 | 100.00% | 46 | 100.00% |
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