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Date: Tue, 2 Oct 2018 12:50:16 +0100 (BST)
From: "Maciej W. Rozycki" <macro@...ux-mips.org>
To: Ralf Baechle <ralf@...ux-mips.org>,
Paul Burton <paul.burton@...s.com>
cc: linux-mips@...ux-mips.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] MIPS: memset: Limit excessive `noreorder' assembly mode
use
Rewrite to use the `reorder' assembly mode and remove manually scheduled
delay slots except where GAS cannot schedule a delay-slot instruction
due to a data dependency or a section switch (as is the case with the EX
macro). No change in machine code produced.
Signed-off-by: Maciej W. Rozycki <macro@...ux-mips.org>
---
arch/mips/lib/memset.S | 48 ++++++++++++++++++++++++------------------------
1 file changed, 24 insertions(+), 24 deletions(-)
linux-mips-memset-reorder.patch
Index: linux-20180930-3maxp-defconfig/arch/mips/lib/memset.S
===================================================================
--- linux-20180930-3maxp-defconfig.orig/arch/mips/lib/memset.S
+++ linux-20180930-3maxp-defconfig/arch/mips/lib/memset.S
@@ -78,7 +78,6 @@
#endif
.endm
- .set noreorder
.align 5
/*
@@ -94,13 +93,16 @@
.endif
sltiu t0, a2, STORSIZE /* very small region? */
+ .set noreorder
bnez t0, .Lsmall_memset\@
andi t0, a0, STORMASK /* aligned? */
+ .set reorder
#ifdef CONFIG_CPU_MICROMIPS
move t8, a1 /* used by 'swp' instruction */
move t9, a1
#endif
+ .set noreorder
#ifndef CONFIG_CPU_DADDI_WORKAROUNDS
beqz t0, 1f
PTR_SUBU t0, STORSIZE /* alignment in bytes */
@@ -111,6 +113,7 @@
PTR_SUBU t0, AT /* alignment in bytes */
.set at
#endif
+ .set reorder
#ifndef CONFIG_CPU_MIPSR6
R10KCBARRIER(0(ra))
@@ -125,8 +128,10 @@
#else /* CONFIG_CPU_MIPSR6 */
#define STORE_BYTE(N) \
EX(sb, a1, N(a0), .Lbyte_fixup\@); \
+ .set noreorder; \
beqz t0, 0f; \
- PTR_ADDU t0, 1;
+ PTR_ADDU t0, 1; \
+ .set reorder;
PTR_ADDU a2, t0 /* correct size */
PTR_ADDU t0, 1
@@ -148,16 +153,14 @@
#endif /* CONFIG_CPU_MIPSR6 */
1: ori t1, a2, 0x3f /* # of full blocks */
xori t1, 0x3f
+ andi t0, a2, 0x40-STORSIZE
beqz t1, .Lmemset_partial\@ /* no block to fill */
- andi t0, a2, 0x40-STORSIZE
PTR_ADDU t1, a0 /* end address */
- .set reorder
1: PTR_ADDIU a0, 64
R10KCBARRIER(0(ra))
f_fill64 a0, -64, FILL64RG, .Lfwd_fixup\@, \mode
bne t1, a0, 1b
- .set noreorder
.Lmemset_partial\@:
R10KCBARRIER(0(ra))
@@ -173,20 +176,18 @@
PTR_SUBU t1, AT
.set at
#endif
+ PTR_ADDU a0, t0 /* dest ptr */
jr t1
- PTR_ADDU a0, t0 /* dest ptr */
- .set push
- .set noreorder
- .set nomacro
/* ... but first do longs ... */
f_fill64 a0, -64, FILL64RG, .Lpartial_fixup\@, \mode
-2: .set pop
- andi a2, STORMASK /* At most one long to go */
+2: andi a2, STORMASK /* At most one long to go */
+ .set noreorder
beqz a2, 1f
#ifndef CONFIG_CPU_MIPSR6
PTR_ADDU a0, a2 /* What's left */
+ .set reorder
R10KCBARRIER(0(ra))
#ifdef __MIPSEB__
EX(LONG_S_R, a1, -1(a0), .Llast_fixup\@)
@@ -195,6 +196,7 @@
#endif
#else
PTR_SUBU t0, $0, a2
+ .set reorder
move a2, zero /* No remaining longs */
PTR_ADDIU t0, 1
STORE_BYTE(0)
@@ -210,20 +212,22 @@
#endif
0:
#endif
-1: jr ra
- move a2, zero
+1: move a2, zero
+ jr ra
.Lsmall_memset\@:
+ PTR_ADDU t1, a0, a2
beqz a2, 2f
- PTR_ADDU t1, a0, a2
1: PTR_ADDIU a0, 1 /* fill bytewise */
R10KCBARRIER(0(ra))
+ .set noreorder
bne t1, a0, 1b
EX(sb, a1, -1(a0), .Lsmall_fixup\@)
+ .set reorder
-2: jr ra /* done */
- move a2, zero
+2: move a2, zero
+ jr ra /* done */
.if __memset == 1
END(memset)
.set __memset, 0
@@ -237,14 +241,13 @@
* a2 = a2 - t0 + 1
*/
PTR_SUBU a2, t0
+ PTR_ADDIU a2, 1
jr ra
- PTR_ADDIU a2, 1
#endif /* CONFIG_CPU_MIPSR6 */
.Lfirst_fixup\@:
/* unset_bytes already in a2 */
jr ra
- nop
.Lfwd_fixup\@:
/*
@@ -255,8 +258,8 @@
andi a2, 0x3f
LONG_L t0, THREAD_BUADDR(t0)
LONG_ADDU a2, t1
+ LONG_SUBU a2, t0
jr ra
- LONG_SUBU a2, t0
.Lpartial_fixup\@:
/*
@@ -267,24 +270,21 @@
andi a2, STORMASK
LONG_L t0, THREAD_BUADDR(t0)
LONG_ADDU a2, a0
+ LONG_SUBU a2, t0
jr ra
- LONG_SUBU a2, t0
.Llast_fixup\@:
/* unset_bytes already in a2 */
jr ra
- nop
.Lsmall_fixup\@:
/*
* unset_bytes = end_addr - current_addr + 1
* a2 = t1 - a0 + 1
*/
- .set reorder
PTR_SUBU a2, t1, a0
PTR_ADDIU a2, 1
jr ra
- .set noreorder
.endm
@@ -298,8 +298,8 @@
LEAF(memset)
EXPORT_SYMBOL(memset)
+ move v0, a0 /* result */
beqz a1, 1f
- move v0, a0 /* result */
andi a1, 0xff /* spread fillword */
LONG_SLL t1, a1, 8
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