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Commit b3a16308 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

x86/fpu: Simplify fpu->fpregs_active use 

The fpregs_active() inline function is pretty pointless - in almost
all the callsites it can be replaced with a direct fpu->fpregs_active
access.

Do so and eliminate the extra layer of obfuscation.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/20170923130016.21448-16-mingo@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 6d7f7da5

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

+1 −16
Original line number Diff line number Diff line
@@ -542,21 +542,6 @@ static inline void fpregs_activate(struct fpu *fpu) 
	trace_x86_fpu_regs_activated(fpu);

}



/*

 * The question "does this thread have fpu access?"

 * is slightly racy, since preemption could come in

 * and revoke it immediately after the test.

 *

 * However, even in that very unlikely scenario,

 * we can just assume we have FPU access - typically

 * to save the FP state - we'll just take a #NM

 * fault and get the FPU access back.

 */

static inline int fpregs_active(void)

{

	return current->thread.fpu.fpregs_active;

}



/*

 * FPU state switching for scheduling.

 *
@@ -617,7 +602,7 @@ static inline void user_fpu_begin(void) 
	struct fpu *fpu = &current->thread.fpu;



	preempt_disable();

	if (!fpregs_active())

	if (!fpu->fpregs_active)

		fpregs_activate(fpu);

	preempt_enable();

}

arch/x86/kernel/fpu/core.c

+1 −1
Original line number Diff line number Diff line
@@ -367,7 +367,7 @@ void fpu__current_fpstate_write_end(void) 
	 * registers may still be out of date.  Update them with

	 * an XRSTOR if they are active.

	 */

	if (fpregs_active())

	if (fpu->fpregs_active)

		copy_kernel_to_fpregs(&fpu->state);



	/*

arch/x86/kernel/fpu/signal.c

+5 −4
Original line number Diff line number Diff line
@@ -155,7 +155,8 @@ static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf) 
 */

int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)

{

	struct xregs_state *xsave = &current->thread.fpu.state.xsave;

	struct fpu *fpu = &current->thread.fpu;

	struct xregs_state *xsave = &fpu->state.xsave;

	struct task_struct *tsk = current;

	int ia32_fxstate = (buf != buf_fx);
@@ -170,13 +171,13 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size) 
			sizeof(struct user_i387_ia32_struct), NULL,

			(struct _fpstate_32 __user *) buf) ? -1 : 1;



	if (fpregs_active() || using_compacted_format()) {

	if (fpu->fpregs_active || using_compacted_format()) {

		/* Save the live register state to the user directly. */

		if (copy_fpregs_to_sigframe(buf_fx))

			return -1;

		/* Update the thread's fxstate to save the fsave header. */

		if (ia32_fxstate)

			copy_fxregs_to_kernel(&tsk->thread.fpu);

			copy_fxregs_to_kernel(fpu);

	} else {

		/*

		 * It is a *bug* if kernel uses compacted-format for xsave
@@ -189,7 +190,7 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size) 
			return -1;

		}



		fpstate_sanitize_xstate(&tsk->thread.fpu);

		fpstate_sanitize_xstate(fpu);

		if (__copy_to_user(buf_fx, xsave, fpu_user_xstate_size))

			return -1;

	}

arch/x86/mm/pkeys.c

+1 −1
Original line number Diff line number Diff line
@@ -45,7 +45,7 @@ int __execute_only_pkey(struct mm_struct *mm) 
	 */

	preempt_disable();

	if (!need_to_set_mm_pkey &&

	    fpregs_active() &&

	    current->thread.fpu.fpregs_active &&

	    !__pkru_allows_read(read_pkru(), execute_only_pkey)) {

		preempt_enable();

		return execute_only_pkey;