Commit a4e22f02 authored Nov 11, 2008 by Mark Nelson Committed by Paul Mackerras Nov 19, 2008

powerpc: Update 64bit __copy_tofrom_user() using CPU_FTR_UNALIGNED_LD_STD



In exactly the same way that we updated memcpy() with new feature
sections in commit 25d6e2d7 ("powerpc:
Update 64bit memcpy() using CPU_FTR_UNALIGNED_LD_STD"), we do the same
thing here for __copy_tofrom_user().  Once again this is purely a
performance tweak for Cell and Power6 - this has no effect on all the
other 64bit powerpc chips.

We can make these same changes to __copy_tofrom_user() because the
basic copy algorithm is the same as in memcpy() - this version just
has all the exception handling logic needed when copying to or from
userspace as well as a special case for copying whole 4K pages that
are page aligned.

CPU_FTR_UNALIGNED_LD_STD CPU was added in commit
4ec577a2 ("powerpc: Add new CPU
feature: CPU_FTR_UNALIGNED_LD_STD").

We also make the same simple one line change from cmpldi r1,... to
cmpldi cr1,... for consistency.

Signed-off-by: Mark Nelson <markn@au1.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

parent 7526ff76

arch/powerpc/lib/copyuser_64.S

+15 −2

Original line number	Diff line number	Diff line
		@@ -26,11 +26,24 @@ _GLOBAL(__copy_tofrom_user)
		andi. r6,r6,7
		PPC_MTOCRF 0x01,r5
		blt cr1,.Lshort_copy
		/* Below we want to nop out the bne if we're on a CPU that has the
		* CPU_FTR_UNALIGNED_LD_STD bit set and the CPU_FTR_CP_USE_DCBTZ bit
		* cleared.
		* At the time of writing the only CPU that has this combination of bits
		* set is Power6.
		*/
		BEGIN_FTR_SECTION
		nop
		FTR_SECTION_ELSE
		bne .Ldst_unaligned
		ALT_FTR_SECTION_END(CPU_FTR_UNALIGNED_LD_STD \| CPU_FTR_CP_USE_DCBTZ, \
		CPU_FTR_UNALIGNED_LD_STD)
		.Ldst_aligned:
		andi. r0,r4,7
		addi r3,r3,-16
		BEGIN_FTR_SECTION
		andi. r0,r4,7
		bne .Lsrc_unaligned
		END_FTR_SECTION_IFCLR(CPU_FTR_UNALIGNED_LD_STD)
		srdi r7,r5,4
		20: ld r9,0(r4)
		addi r4,r4,-8
		@@ -138,7 +151,7 @@ _GLOBAL(__copy_tofrom_user)
		PPC_MTOCRF 0x01,r6 /* put #bytes to 8B bdry into cr7 */
		subf r5,r6,r5
		li r7,0
		cmpldi r1,r5,16
		cmpldi cr1,r5,16
		bf cr7*4+3,1f
		35: lbz r0,0(r4)
		81: stb r0,0(r3)