LoongArch: Use alternative to optimize libraries

Use the alternative to optimize common libraries according whether CPU
has UAL (hardware unaligned access support) feature, including memset(),
memcopy(), memmove(), copy_user() and clear_user().

We have tested UnixBench on a Loongson-3A5000 quad-core machine (1.6GHz):

1, One copy, before patch:

System Benchmarks Index Values               BASELINE       RESULT    INDEX
Dhrystone 2 using register variables         116700.0    9566582.0    819.8
Double-Precision Whetstone                       55.0       2805.3    510.1
Execl Throughput                                 43.0       2120.0    493.0
File Copy 1024 bufsize 2000 maxblocks          3960.0     209833.0    529.9
File Copy 256 bufsize 500 maxblocks            1655.0      89400.0    540.2
File Copy 4096 bufsize 8000 maxblocks          5800.0     320036.0    551.8
Pipe Throughput                               12440.0     340624.0    273.8
Pipe-based Context Switching                   4000.0     109939.1    274.8
Process Creation                                126.0       4728.7    375.3
Shell Scripts (1 concurrent)                     42.4       2223.1    524.3
Shell Scripts (8 concurrent)                      6.0        883.1   1471.9
System Call Overhead                          15000.0     518639.1    345.8
                                                                   ========
System Benchmarks Index Score                                         500.2

2, One copy, after patch:

System Benchmarks Index Values               BASELINE       RESULT    INDEX
Dhrystone 2 using register variables         116700.0    9567674.7    819.9
Double-Precision Whetstone                       55.0       2805.5    510.1
Execl Throughput                                 43.0       2392.7    556.4
File Copy 1024 bufsize 2000 maxblocks          3960.0     417804.0   1055.1
File Copy 256 bufsize 500 maxblocks            1655.0     112909.5    682.2
File Copy 4096 bufsize 8000 maxblocks          5800.0    1255207.4   2164.2
Pipe Throughput                               12440.0     555712.0    446.7
Pipe-based Context Switching                   4000.0      99964.5    249.9
Process Creation                                126.0       5192.5    412.1
Shell Scripts (1 concurrent)                     42.4       2302.4    543.0
Shell Scripts (8 concurrent)                      6.0        919.6   1532.6
System Call Overhead                          15000.0     511159.3    340.8
                                                                   ========
System Benchmarks Index Score                                         640.1

3, Four copies, before patch:

System Benchmarks Index Values               BASELINE       RESULT    INDEX
Dhrystone 2 using register variables         116700.0   38268610.5   3279.2
Double-Precision Whetstone                       55.0      11222.2   2040.4
Execl Throughput                                 43.0       7892.0   1835.3
File Copy 1024 bufsize 2000 maxblocks          3960.0     235149.6    593.8
File Copy 256 bufsize 500 maxblocks            1655.0      74959.6    452.9
File Copy 4096 bufsize 8000 maxblocks          5800.0     545048.5    939.7
Pipe Throughput                               12440.0    1337359.0   1075.0
Pipe-based Context Switching                   4000.0     473663.9   1184.2
Process Creation                                126.0      17491.2   1388.2
Shell Scripts (1 concurrent)                     42.4       6865.7   1619.3
Shell Scripts (8 concurrent)                      6.0       1015.9   1693.1
System Call Overhead                          15000.0    1899535.2   1266.4
                                                                   ========
System Benchmarks Index Score                                        1278.3

4, Four copies, after patch:

System Benchmarks Index Values               BASELINE       RESULT    INDEX
Dhrystone 2 using register variables         116700.0   38272815.5   3279.6
Double-Precision Whetstone                       55.0      11222.8   2040.5
Execl Throughput                                 43.0       8839.2   2055.6
File Copy 1024 bufsize 2000 maxblocks          3960.0     313912.9    792.7
File Copy 256 bufsize 500 maxblocks            1655.0      80976.1    489.3
File Copy 4096 bufsize 8000 maxblocks          5800.0    1176594.3   2028.6
Pipe Throughput                               12440.0    2100941.9   1688.9
Pipe-based Context Switching                   4000.0     476696.4   1191.7
Process Creation                                126.0      18394.7   1459.9
Shell Scripts (1 concurrent)                     42.4       7172.2   1691.6
Shell Scripts (8 concurrent)                      6.0       1058.3   1763.9
System Call Overhead                          15000.0    1874714.7   1249.8
                                                                   ========
System Benchmarks Index Score                                        1488.8

Signed-off-by: Jun Yi <yijun@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

1 files changed, 65 insertions, 5 deletions

diff --git a/arch/loongarch/lib/clear_user.S b/arch/loongarch/lib/clear_user.S
index d5c9e44ac8c4..2dc48e61a2c8 100644
--- a/arch/loongarch/lib/clear_user.S
+++ b/arch/loongarch/lib/clear_user.S
@@ -3,25 +3,37 @@
  * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
  */
 
+#include <asm/alternative-asm.h>
 #include <asm/asm.h>
 #include <asm/asmmacro.h>
 #include <asm/asm-extable.h>
+#include <asm/cpu.h>
 #include <asm/export.h>
 #include <asm/regdef.h>
 
-.irp to, 0
+.irp to, 0, 1, 2, 3, 4, 5, 6, 7
 .L_fixup_handle_\to\():
 	addi.d	a0, a1, (\to) * (-8)
 	jr	ra
 .endr
 
+SYM_FUNC_START(__clear_user)
+	/*
+	 * Some CPUs support hardware unaligned access
+	 */
+	ALTERNATIVE	"b __clear_user_generic",	\
+			"b __clear_user_fast", CPU_FEATURE_UAL
+SYM_FUNC_END(__clear_user)
+
+EXPORT_SYMBOL(__clear_user)
+
 /*
- * unsigned long __clear_user(void *addr, size_t size)
+ * unsigned long __clear_user_generic(void *addr, size_t size)
  *
  * a0: addr
  * a1: size
  */
-SYM_FUNC_START(__clear_user)
+SYM_FUNC_START(__clear_user_generic)
 	beqz	a1, 2f
 
 1:	st.b	zero, a0, 0
@@ -33,6 +45,54 @@ SYM_FUNC_START(__clear_user)
 	jr	ra
 
 	_asm_extable 1b, .L_fixup_handle_0
-SYM_FUNC_END(__clear_user)
+SYM_FUNC_END(__clear_user_generic)
 
-EXPORT_SYMBOL(__clear_user)
+/*
+ * unsigned long __clear_user_fast(void *addr, unsigned long size)
+ *
+ * a0: addr
+ * a1: size
+ */
+SYM_FUNC_START(__clear_user_fast)
+	beqz	a1, 10f
+
+	ori	a2, zero, 64
+	blt	a1, a2, 9f
+
+	/* set 64 bytes at a time */
+1:	st.d	zero, a0, 0
+2:	st.d	zero, a0, 8
+3:	st.d	zero, a0, 16
+4:	st.d	zero, a0, 24
+5:	st.d	zero, a0, 32
+6:	st.d	zero, a0, 40
+7:	st.d	zero, a0, 48
+8:	st.d	zero, a0, 56
+
+	addi.d	a0, a0, 64
+	addi.d	a1, a1, -64
+	bge	a1, a2, 1b
+
+	beqz	a1, 10f
+
+	/* set the remaining bytes */
+9:	st.b	zero, a0, 0
+	addi.d	a0, a0, 1
+	addi.d	a1, a1, -1
+	bgt	a1, zero, 9b
+
+	/* return */
+10:	move	a0, a1
+	jr	ra
+
+	/* fixup and ex_table */
+	_asm_extable 1b, .L_fixup_handle_0
+	_asm_extable 2b, .L_fixup_handle_1
+	_asm_extable 3b, .L_fixup_handle_2
+	_asm_extable 4b, .L_fixup_handle_3
+	_asm_extable 5b, .L_fixup_handle_4
+	_asm_extable 6b, .L_fixup_handle_5
+	_asm_extable 7b, .L_fixup_handle_6
+	_asm_extable 8b, .L_fixup_handle_7
+	_asm_extable 9b, .L_fixup_handle_0
+SYM_FUNC_END(__clear_user_fast)