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Commit ac1dc365 authored by Anton Blanchard's avatar Anton Blanchard Committed by Benjamin Herrenschmidt
Browse files

powerpc: Clear RI and EE at the same time in system call exit 



mtmsrd is an expensive instruction, we save a few cycles by
doing it once instead of twice.

Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent a9514dc6

arch/powerpc/kernel/entry_64.S

+13 −12
Original line number Diff line number Diff line
@@ -197,7 +197,16 @@ syscall_exit: 
	wrteei	0

#else

	ld	r10,PACAKMSR(r13)

	mtmsrd	r10,1

	/*

	 * For performance reasons we clear RI the same time that we

	 * clear EE. We only need to clear RI just before we restore r13

	 * below, but batching it with EE saves us one expensive mtmsrd call.

	 * We have to be careful to restore RI if we branch anywhere from

	 * here (eg syscall_exit_work).

	 */

	li	r9,MSR_RI

	andc	r11,r10,r9

	mtmsrd	r11,1

#endif /* CONFIG_PPC_BOOK3E */



	ld	r9,TI_FLAGS(r12)
@@ -214,17 +223,6 @@ BEGIN_FTR_SECTION 
END_FTR_SECTION_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)

	andi.	r6,r8,MSR_PR

	ld	r4,_LINK(r1)

	/*

	 * Clear RI before restoring r13.  If we are returning to

	 * userspace and we take an exception after restoring r13,

	 * we end up corrupting the userspace r13 value.

	 */

#ifdef CONFIG_PPC_BOOK3S

	/* No MSR:RI on BookE */

	li	r12,MSR_RI

	andc	r11,r10,r12

	mtmsrd	r11,1			/* clear MSR.RI */

#endif /* CONFIG_PPC_BOOK3S */



	beq-	1f

	ACCOUNT_CPU_USER_EXIT(r11, r12)
@@ -271,6 +269,9 @@ syscall_enosys: 
	b	syscall_exit

	

syscall_exit_work:

#ifdef CONFIG_PPC_BOOK3S

	mtmsrd	r10,1		/* Restore RI */

#endif

	/* If TIF_RESTOREALL is set, don't scribble on either r3 or ccr.

	 If TIF_NOERROR is set, just save r3 as it is. */