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x86/fpu: Split out the fpu__activate_fpstate_read() method 

Currently fpu__activate_fpstate() is used for two distinct purposes:

  - read access by ptrace and core dumping, where in the core dumping
    case the current task's FPU state may be examined as well.

  - write access by ptrace, which modifies FPU registers and expects
    the modified registers to be reloaded on the next context switch.

Split out the reading side into fpu__activate_fpstate_read().

( Note that this is just a pure duplication of fpu__activate_fpstate()
  for the time being, we'll optimize the new function in the next patch. )

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Bobby Powers <bobbypowers@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
hifive-unleashed-5.1
Ingo Molnar 2015-05-27 12:22:29 +02:00
parent 47f01e8cc2
commit 0560281266
3 changed files with 33 additions and 3 deletions
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1
arch/x86/include/asm/fpu/internal.h
View File

@ -22,6 +22,7 @@
* High level FPU state handling functions:
*/
extern void fpu__activate_curr(struct fpu *fpu);
extern void fpu__activate_fpstate_read(struct fpu *fpu);
extern void fpu__activate_fpstate(struct fpu *fpu);
extern void fpu__save(struct fpu *fpu);
extern void fpu__restore(struct fpu *fpu);

29
arch/x86/kernel/fpu/core.c
View File

@ -295,6 +295,35 @@ void fpu__activate_curr(struct fpu *fpu)
}
EXPORT_SYMBOL_GPL(fpu__activate_curr);
/*
* This function must be called before we read a task's fpstate.
*
* If the task has not used the FPU before then initialize its
* fpstate.
*
* If the task has used the FPU before then save it.
*/
void fpu__activate_fpstate_read(struct fpu *fpu)
{
/*
* If fpregs are active (in the current CPU), then
* copy them to the fpstate:
*/
if (fpu->fpregs_active) {
fpu__save(fpu);
} else {
if (fpu->fpstate_active) {
/* Invalidate any lazy state: */
fpu->last_cpu = -1;
} else {
fpstate_init(&fpu->state);
/* Safe to do for current and for stopped child tasks: */
fpu->fpstate_active = 1;
}
}
}
/*
* This function must be called before we read or write a task's fpstate.
*

6
arch/x86/kernel/fpu/regset.c
View File

@ -33,7 +33,7 @@ int xfpregs_get(struct task_struct *target, const struct user_regset *regset,
if (!cpu_has_fxsr)
return -ENODEV;
fpu__activate_fpstate(fpu);
fpu__activate_fpstate_read(fpu);
fpstate_sanitize_xstate(fpu);
return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
@ -82,7 +82,7 @@ int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
if (!cpu_has_xsave)
return -ENODEV;
fpu__activate_fpstate(fpu);
fpu__activate_fpstate_read(fpu);
xsave = &fpu->state.xsave;
@ -273,7 +273,7 @@ int fpregs_get(struct task_struct *target, const struct user_regset *regset,
struct fpu *fpu = &target->thread.fpu;
struct user_i387_ia32_struct env;
fpu__activate_fpstate(fpu);
fpu__activate_fpstate_read(fpu);
if (!static_cpu_has(X86_FEATURE_FPU))
return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);