This function is a misnomer on two levels:
1) it doesn't really manipulate TS on modern CPUs anymore, its
primary purpose is to save FPU state, used:
- when executing fork()/clone(): to copy current FPU state
to the child's FPU state.
- when handling math exceptions: to generate the math error
si_code in the signal frame.
2) even on legacy CPUs it doesn't actually 'unlazy', if then
it lazies the FPU state: as a side effect of the old FNSAVE
instruction which clears (destroys) FPU state it's necessary
to set CR0::TS.
So rename it to fpu__save() to better reflect its purpose.
Reviewed-by: Borislav Petkov <b...@alien8.de>
Cc: Andy Lutomirski <l...@amacapital.net>
Cc: Dave Hansen <dave.han...@linux.intel.com>
Cc: Fenghua Yu <fenghua...@intel.com>
Cc: H. Peter Anvin <h...@zytor.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Oleg Nesterov <o...@redhat.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Signed-off-by: Ingo Molnar <mi...@kernel.org>
---
arch/x86/include/asm/fpu-internal.h | 2 +-
arch/x86/include/asm/i387.h | 2 +-
arch/x86/kernel/i387.c | 6 +++---
arch/x86/kernel/traps.c | 2 +-
4 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/fpu-internal.h
b/arch/x86/include/asm/fpu-internal.h
index da5e96756570..49db0440b0ed 100644
--- a/arch/x86/include/asm/fpu-internal.h
+++ b/arch/x86/include/asm/fpu-internal.h
@@ -602,7 +602,7 @@ static inline void fpu_copy(struct task_struct *dst, struct
task_struct *src)
struct fpu *dfpu = &dst->thread.fpu;
struct fpu *sfpu = &src->thread.fpu;
- unlazy_fpu(src);
+ fpu__save(src);
memcpy(dfpu->state, sfpu->state, xstate_size);
}
}
diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
index 6eb6fcb83f63..d4419da9b210 100644
--- a/arch/x86/include/asm/i387.h
+++ b/arch/x86/include/asm/i387.h
@@ -101,7 +101,7 @@ static inline int user_has_fpu(void)
return current->thread.fpu.has_fpu;
}
-extern void unlazy_fpu(struct task_struct *tsk);
+extern void fpu__save(struct task_struct *tsk);
#endif /* __ASSEMBLY__ */
diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index 009183276bb7..ec1a744eb853 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -117,7 +117,7 @@ void __kernel_fpu_end(void)
}
EXPORT_SYMBOL(__kernel_fpu_end);
-void unlazy_fpu(struct task_struct *tsk)
+void fpu__save(struct task_struct *tsk)
{
preempt_disable();
if (__thread_has_fpu(tsk)) {
@@ -130,7 +130,7 @@ void unlazy_fpu(struct task_struct *tsk)
}
preempt_enable();
}
-EXPORT_SYMBOL(unlazy_fpu);
+EXPORT_SYMBOL(fpu__save);
unsigned int mxcsr_feature_mask __read_mostly = 0xffffffffu;
unsigned int xstate_size;
@@ -251,7 +251,7 @@ int init_fpu(struct task_struct *tsk)
if (tsk_used_math(tsk)) {
if (cpu_has_fpu && tsk == current)
- unlazy_fpu(tsk);
+ fpu__save(tsk);
task_disable_lazy_fpu_restore(tsk);
return 0;
}
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 324ab5247687..12f29f9907cd 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -731,7 +731,7 @@ static void math_error(struct pt_regs *regs, int
error_code, int trapnr)
/*
* Save the info for the exception handler and clear the error.
*/
- unlazy_fpu(task);
+ fpu__save(task);
task->thread.trap_nr = trapnr;
task->thread.error_code = error_code;
info.si_signo = SIGFPE;
--
2.1.0
--
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