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Merge branch 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull x86 FPU updates from Thomas Gleixner:
 "A small set of updates for the FPU code:

   - Make the no387/nofxsr command line options useful by restricting
     them to 32bit and actually clearing all dependencies to prevent
     random crashes and malfunction.

   - Simplify and cleanup the kernel_fpu_*() helpers"

* 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/fpu: Inline fpu__xstate_clear_all_cpu_caps()
  x86/fpu: Make 'no387' and 'nofxsr' command line options useful
  x86/fpu: Remove the fpu__save() export
  x86/fpu: Simplify kernel_fpu_begin()
  x86/fpu: Simplify kernel_fpu_end()
This commit is contained in:
Linus Torvalds 2019-07-08 11:45:26 -07:00
commit ab2486a9ee
5 changed files with 33 additions and 63 deletions
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1
arch/x86/include/asm/fpu/xstate.h
View file

@ -47,7 +47,6 @@ extern u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS];
extern void __init update_regset_xstate_info(unsigned int size,
u64 xstate_mask);
void fpu__xstate_clear_all_cpu_caps(void);
void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr);
const void *get_xsave_field_ptr(int xfeature_nr);
int using_compacted_format(void);

5
arch/x86/kernel/cpu/cpuid-deps.c
View file

@ -20,6 +20,7 @@ struct cpuid_dep {
* but it's difficult to tell that to the init reference checker.
*/
static const struct cpuid_dep cpuid_deps[] = {
{ X86_FEATURE_FXSR, X86_FEATURE_FPU },
{ X86_FEATURE_XSAVEOPT, X86_FEATURE_XSAVE },
{ X86_FEATURE_XSAVEC, X86_FEATURE_XSAVE },
{ X86_FEATURE_XSAVES, X86_FEATURE_XSAVE },
@ -27,7 +28,11 @@ static const struct cpuid_dep cpuid_deps[] = {
{ X86_FEATURE_PKU, X86_FEATURE_XSAVE },
{ X86_FEATURE_MPX, X86_FEATURE_XSAVE },
{ X86_FEATURE_XGETBV1, X86_FEATURE_XSAVE },
{ X86_FEATURE_CMOV, X86_FEATURE_FXSR },
{ X86_FEATURE_MMX, X86_FEATURE_FXSR },
{ X86_FEATURE_MMXEXT, X86_FEATURE_MMX },
{ X86_FEATURE_FXSR_OPT, X86_FEATURE_FXSR },
{ X86_FEATURE_XSAVE, X86_FEATURE_FXSR },
{ X86_FEATURE_XMM, X86_FEATURE_FXSR },
{ X86_FEATURE_XMM2, X86_FEATURE_XMM },
{ X86_FEATURE_XMM3, X86_FEATURE_XMM2 },

60
arch/x86/kernel/fpu/core.c
View file

@ -43,18 +43,6 @@ static DEFINE_PER_CPU(bool, in_kernel_fpu);
*/
DEFINE_PER_CPU(struct fpu *, fpu_fpregs_owner_ctx);
static void kernel_fpu_disable(void)
{
WARN_ON_FPU(this_cpu_read(in_kernel_fpu));
this_cpu_write(in_kernel_fpu, true);
}
static void kernel_fpu_enable(void)
{
WARN_ON_FPU(!this_cpu_read(in_kernel_fpu));
this_cpu_write(in_kernel_fpu, false);
}
static bool kernel_fpu_disabled(void)
{
return this_cpu_read(in_kernel_fpu);
@ -94,42 +82,33 @@ bool irq_fpu_usable(void)
}
EXPORT_SYMBOL(irq_fpu_usable);
static void __kernel_fpu_begin(void)
{
struct fpu *fpu = &current->thread.fpu;
WARN_ON_FPU(!irq_fpu_usable());
kernel_fpu_disable();
if (!(current->flags & PF_KTHREAD)) {
if (!test_thread_flag(TIF_NEED_FPU_LOAD)) {
set_thread_flag(TIF_NEED_FPU_LOAD);
/*
* Ignore return value -- we don't care if reg state
* is clobbered.
*/
copy_fpregs_to_fpstate(fpu);
}
}
__cpu_invalidate_fpregs_state();
}
static void __kernel_fpu_end(void)
{
kernel_fpu_enable();
}
void kernel_fpu_begin(void)
{
preempt_disable();
__kernel_fpu_begin();
WARN_ON_FPU(!irq_fpu_usable());
WARN_ON_FPU(this_cpu_read(in_kernel_fpu));
this_cpu_write(in_kernel_fpu, true);
if (!(current->flags & PF_KTHREAD) &&
!test_thread_flag(TIF_NEED_FPU_LOAD)) {
set_thread_flag(TIF_NEED_FPU_LOAD);
/*
* Ignore return value -- we don't care if reg state
* is clobbered.
*/
copy_fpregs_to_fpstate(&current->thread.fpu);
}
__cpu_invalidate_fpregs_state();
}
EXPORT_SYMBOL_GPL(kernel_fpu_begin);
void kernel_fpu_end(void)
{
__kernel_fpu_end();
WARN_ON_FPU(!this_cpu_read(in_kernel_fpu));
this_cpu_write(in_kernel_fpu, false);
preempt_enable();
}
EXPORT_SYMBOL_GPL(kernel_fpu_end);
@ -155,7 +134,6 @@ void fpu__save(struct fpu *fpu)
trace_x86_fpu_after_save(fpu);
fpregs_unlock();
}
EXPORT_SYMBOL_GPL(fpu__save);
/*
* Legacy x87 fpstate state init:

19
arch/x86/kernel/fpu/init.c
View file

@ -204,12 +204,6 @@ static void __init fpu__init_system_xstate_size_legacy(void)
*/
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))
@ -252,17 +246,20 @@ static void __init fpu__init_parse_early_param(void)
char *argptr = arg;
int bit;
#ifdef CONFIG_X86_32
if (cmdline_find_option_bool(boot_command_line, "no387"))
#ifdef CONFIG_MATH_EMULATION
setup_clear_cpu_cap(X86_FEATURE_FPU);
#else
pr_err("Option 'no387' required CONFIG_MATH_EMULATION enabled.\n");
#endif
if (cmdline_find_option_bool(boot_command_line, "nofxsr")) {
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);
}
#endif
if (cmdline_find_option_bool(boot_command_line, "noxsave"))
fpu__xstate_clear_all_cpu_caps();
setup_clear_cpu_cap(X86_FEATURE_XSAVE);
if (cmdline_find_option_bool(boot_command_line, "noxsaveopt"))
setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);

11
arch/x86/kernel/fpu/xstate.c
View file

@ -67,15 +67,6 @@ static unsigned int xstate_comp_offsets[sizeof(xfeatures_mask)*8];
*/
unsigned int fpu_user_xstate_size;
/*
* Clear all of the X86_FEATURE_* bits that are unavailable
* when the CPU has no XSAVE support.
*/
void fpu__xstate_clear_all_cpu_caps(void)
{
setup_clear_cpu_cap(X86_FEATURE_XSAVE);
}
/*
* Return whether the system supports a given xfeature.
*
@ -709,7 +700,7 @@ static void fpu__init_disable_system_xstate(void)
{
xfeatures_mask = 0;
cr4_clear_bits(X86_CR4_OSXSAVE);
fpu__xstate_clear_all_cpu_caps();
setup_clear_cpu_cap(X86_FEATURE_XSAVE);
}
/*