Commit 05602812 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

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: default avatarIngo Molnar <mingo@kernel.org>
parent 47f01e8c

arch/x86/include/asm/fpu/internal.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

arch/x86/kernel/fpu/core.c

+29 −0
Original line number Diff line number Diff line
@@ -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.

 *

arch/x86/kernel/fpu/regset.c

+3 −3
Original line number Diff line number Diff line
@@ -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);

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