* [PATCH v5 2/4] selftests/powerpc: Add test for strlen()
2018-06-08 13:27 [PATCH v5 1/4] selftests/powerpc: add test for 32 bits memcmp Christophe Leroy
@ 2018-06-08 13:27 ` Christophe Leroy
2018-06-08 13:27 ` [PATCH v5 3/4] powerpc/lib: implement strlen() in assembly Christophe Leroy
2018-06-08 13:27 ` [PATCH v5 4/4] selftests/powerpc: update strlen() test to test the new assembly function Christophe Leroy
2 siblings, 0 replies; 5+ messages in thread
From: Christophe Leroy @ 2018-06-08 13:27 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman,
wei.guo.simon
Cc: linux-kernel, linuxppc-dev
This patch adds a test for strlen()
string.c contains a copy of strlen() from lib/string.c
The test first tests the correctness of strlen() by comparing
the result with libc strlen(). It tests all cases of alignment.
It them tests the duration of an aligned strlen() on a 4 bytes string,
on a 16 bytes string and on a 256 bytes string.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
v5: no change
v4: new
.../testing/selftests/powerpc/stringloops/Makefile | 5 +-
.../testing/selftests/powerpc/stringloops/string.c | 36 ++++++
.../testing/selftests/powerpc/stringloops/strlen.c | 123 +++++++++++++++++++++
3 files changed, 163 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/powerpc/stringloops/string.c
create mode 100644 tools/testing/selftests/powerpc/stringloops/strlen.c
diff --git a/tools/testing/selftests/powerpc/stringloops/Makefile b/tools/testing/selftests/powerpc/stringloops/Makefile
index 1e7301d4bac9..df663ee9ddb3 100644
--- a/tools/testing/selftests/powerpc/stringloops/Makefile
+++ b/tools/testing/selftests/powerpc/stringloops/Makefile
@@ -10,9 +10,12 @@ $(OUTPUT)/memcmp_64: CFLAGS += -m64
$(OUTPUT)/memcmp_32: memcmp.c
$(OUTPUT)/memcmp_32: CFLAGS += -m32
+$(OUTPUT)/strlen: strlen.c string.o
+$(OUTPUT)/string.o: string.c
+
ASFLAGS = $(CFLAGS)
-TEST_GEN_PROGS := memcmp_32 memcmp_64
+TEST_GEN_PROGS := memcmp_32 memcmp_64 strlen
include ../../lib.mk
diff --git a/tools/testing/selftests/powerpc/stringloops/string.c b/tools/testing/selftests/powerpc/stringloops/string.c
new file mode 100644
index 000000000000..d05200481017
--- /dev/null
+++ b/tools/testing/selftests/powerpc/stringloops/string.c
@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/lib/string.c
+ *
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ */
+
+/*
+ * stupid library routines.. The optimized versions should generally be found
+ * as inline code in <asm-xx/string.h>
+ *
+ * These are buggy as well..
+ *
+ * * Fri Jun 25 1999, Ingo Oeser <ioe@informatik.tu-chemnitz.de>
+ * - Added strsep() which will replace strtok() soon (because strsep() is
+ * reentrant and should be faster). Use only strsep() in new code, please.
+ *
+ * * Sat Feb 09 2002, Jason Thomas <jason@topic.com.au>,
+ * Matthew Hawkins <matt@mh.dropbear.id.au>
+ * - Kissed strtok() goodbye
+ */
+
+#include <stddef.h>
+
+/**
+ * strlen - Find the length of a string
+ * @s: The string to be sized
+ */
+size_t test_strlen(const char *s)
+{
+ const char *sc;
+
+ for (sc = s; *sc != '\0'; ++sc)
+ /* nothing */;
+ return sc - s;
+}
diff --git a/tools/testing/selftests/powerpc/stringloops/strlen.c b/tools/testing/selftests/powerpc/stringloops/strlen.c
new file mode 100644
index 000000000000..e87ca65ea156
--- /dev/null
+++ b/tools/testing/selftests/powerpc/stringloops/strlen.c
@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <malloc.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include "utils.h"
+
+#define SIZE 256
+#define ITERATIONS 1000
+#define ITERATIONS_BENCH 100000
+
+int test_strlen(const void *s);
+
+/* test all offsets and lengths */
+static void test_one(char *s)
+{
+ unsigned long offset;
+
+ for (offset = 0; offset < SIZE; offset++) {
+ int x, y;
+ unsigned long i;
+
+ y = strlen(s + offset);
+ x = test_strlen(s + offset);
+
+ if (x != y) {
+ printf("strlen() returned %d, should have returned %d (%p offset %ld)\n", x, y, s, offset);
+
+ for (i = offset; i < SIZE; i++)
+ printf("%02x ", s[i]);
+ printf("\n");
+ }
+ }
+}
+
+static int testcase(void)
+{
+ char *s;
+ unsigned long i;
+ struct timespec ts_start, ts_end;
+
+ s = memalign(128, SIZE);
+ if (!s) {
+ perror("memalign");
+ exit(1);
+ }
+
+ srandom(1);
+
+ memset(s, 0, SIZE);
+ for (i = 0; i < SIZE; i++) {
+ char c;
+
+ do {
+ c = random() & 0x7f;
+ } while (!c);
+ s[i] = c;
+ test_one(s);
+ }
+
+ for (i = 0; i < ITERATIONS; i++) {
+ unsigned long j;
+
+ for (j = 0; j < SIZE; j++) {
+ char c;
+
+ do {
+ c = random() & 0x7f;
+ } while (!c);
+ s[j] = c;
+ }
+ for (j = 0; j < sizeof(long); j++) {
+ s[SIZE - 1 - j] = 0;
+ test_one(s);
+ }
+ }
+
+ for (i = 0; i < SIZE; i++) {
+ char c;
+
+ do {
+ c = random() & 0x7f;
+ } while (!c);
+ s[i] = c;
+ }
+
+ clock_gettime(CLOCK_MONOTONIC, &ts_start);
+
+ s[SIZE - 1] = 0;
+ for (i = 0; i < ITERATIONS_BENCH; i++)
+ test_strlen(s);
+
+ clock_gettime(CLOCK_MONOTONIC, &ts_end);
+
+ printf("len %3.3d : time = %.6f\n", SIZE, ts_end.tv_sec - ts_start.tv_sec + (ts_end.tv_nsec - ts_start.tv_nsec) / 1e9);
+
+ clock_gettime(CLOCK_MONOTONIC, &ts_start);
+
+ s[16] = 0;
+ for (i = 0; i < ITERATIONS_BENCH; i++)
+ test_strlen(s);
+
+ clock_gettime(CLOCK_MONOTONIC, &ts_end);
+
+ printf("len 16 : time = %.6f\n", ts_end.tv_sec - ts_start.tv_sec + (ts_end.tv_nsec - ts_start.tv_nsec) / 1e9);
+
+ clock_gettime(CLOCK_MONOTONIC, &ts_start);
+
+ s[4] = 0;
+ for (i = 0; i < ITERATIONS_BENCH; i++)
+ test_strlen(s);
+
+ clock_gettime(CLOCK_MONOTONIC, &ts_end);
+
+ printf("len 4 : time = %.6f\n", ts_end.tv_sec - ts_start.tv_sec + (ts_end.tv_nsec - ts_start.tv_nsec) / 1e9);
+
+ return 0;
+}
+
+int main(void)
+{
+ return test_harness(testcase, "strlen");
+}
--
2.13.3
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v5 3/4] powerpc/lib: implement strlen() in assembly
2018-06-08 13:27 [PATCH v5 1/4] selftests/powerpc: add test for 32 bits memcmp Christophe Leroy
2018-06-08 13:27 ` [PATCH v5 2/4] selftests/powerpc: Add test for strlen() Christophe Leroy
@ 2018-06-08 13:27 ` Christophe Leroy
2018-06-08 14:54 ` Segher Boessenkool
2018-06-08 13:27 ` [PATCH v5 4/4] selftests/powerpc: update strlen() test to test the new assembly function Christophe Leroy
2 siblings, 1 reply; 5+ messages in thread
From: Christophe Leroy @ 2018-06-08 13:27 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman,
wei.guo.simon
Cc: linux-kernel, linuxppc-dev
The generic implementation of strlen() reads strings byte per byte.
This patch implements strlen() in assembly based on a read of entire
words, in the same spirit as what some other arches and glibc do.
On a 8xx the time spent in strlen is reduced by 2/3 for long strings.
strlen() selftest on an 8xx provides the following values:
Before the patch (ie with the generic strlen() in lib/string.c):
len 256 : time = 0.803648
len 16 : time = 0.062989
len 4 : time = 0.026269
After the patch:
len 256 : time = 0.267791 ==> 66% improvment
len 16 : time = 0.037902 ==> 41% improvment
len 4 : time = 0.026124 ==> no degradation
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
Not tested on PPC64.
Changes in v5:
- Fixed for PPC64 LITTLE ENDIAN
Changes in v4:
- Added alignment of the loop
- doing the andc only if still not 0 as it happends only for bytes above 0x7f which is pretty rare in a string
Changes in v3:
- Made it common to PPC32 and PPC64
Changes in v2:
- Moved handling of unaligned strings outside of the main path as it is very unlikely.
- Removed the verification of the fourth byte in case none of the three first ones are NUL.
arch/powerpc/include/asm/asm-compat.h | 4 ++
arch/powerpc/include/asm/string.h | 1 +
arch/powerpc/lib/string.S | 76 +++++++++++++++++++++++++++++++++++
3 files changed, 81 insertions(+)
diff --git a/arch/powerpc/include/asm/asm-compat.h b/arch/powerpc/include/asm/asm-compat.h
index 7f2a7702596c..0e99fe7570c0 100644
--- a/arch/powerpc/include/asm/asm-compat.h
+++ b/arch/powerpc/include/asm/asm-compat.h
@@ -20,8 +20,10 @@
/* operations for longs and pointers */
#define PPC_LL stringify_in_c(ld)
+#define PPC_LLU stringify_in_c(ldu)
#define PPC_STL stringify_in_c(std)
#define PPC_STLU stringify_in_c(stdu)
+#define PPC_ROTLI stringify_in_c(rotldi)
#define PPC_LCMPI stringify_in_c(cmpdi)
#define PPC_LCMPLI stringify_in_c(cmpldi)
#define PPC_LCMP stringify_in_c(cmpd)
@@ -53,8 +55,10 @@
/* operations for longs and pointers */
#define PPC_LL stringify_in_c(lwz)
+#define PPC_LLU stringify_in_c(lwzu)
#define PPC_STL stringify_in_c(stw)
#define PPC_STLU stringify_in_c(stwu)
+#define PPC_ROTLI stringify_in_c(rotlwi)
#define PPC_LCMPI stringify_in_c(cmpwi)
#define PPC_LCMPLI stringify_in_c(cmplwi)
#define PPC_LCMP stringify_in_c(cmpw)
diff --git a/arch/powerpc/include/asm/string.h b/arch/powerpc/include/asm/string.h
index 9b8cedf618f4..8fdcb532de72 100644
--- a/arch/powerpc/include/asm/string.h
+++ b/arch/powerpc/include/asm/string.h
@@ -13,6 +13,7 @@
#define __HAVE_ARCH_MEMCHR
#define __HAVE_ARCH_MEMSET16
#define __HAVE_ARCH_MEMCPY_FLUSHCACHE
+#define __HAVE_ARCH_STRLEN
extern char * strcpy(char *,const char *);
extern char * strncpy(char *,const char *, __kernel_size_t);
diff --git a/arch/powerpc/lib/string.S b/arch/powerpc/lib/string.S
index 4b41970e9ed8..1bb8e178c843 100644
--- a/arch/powerpc/lib/string.S
+++ b/arch/powerpc/lib/string.S
@@ -67,3 +67,79 @@ _GLOBAL(memchr)
2: li r3,0
blr
EXPORT_SYMBOL(memchr)
+
+_GLOBAL(strlen)
+ andi. r9, r3, (SZL - 1)
+ addi r10, r3, -SZL
+ bne- 1f
+2: lis r6, 0x8080
+ ori r6, r6, 0x8080 /* r6 = 0x80808080 (himagic) */
+#ifdef CONFIG_PPC64
+ rldimi r6, r6, 32, 0 /* r6 = 0x8080808080808080 (himagic) */
+#endif
+ PPC_ROTLI r7, r6, 1 /* r7 = 0x01010101(01010101) (lomagic)*/
+ .balign IFETCH_ALIGN_BYTES
+3: PPC_LLU r9, SZL(r10)
+ /* ((x - lomagic) & ~x & himagic) == 0 means no byte in x is NUL */
+ subf r8, r7, r9
+ and. r8, r8, r6
+ beq+ 3b
+ andc. r8, r8, r9
+ beq+ 3b
+#ifdef CPU_LITTLE_ENDIAN
+ rldicl. r8, r9, 0, 56
+ beq 20f
+ rldicl. r8, r9, 56, 56
+ beq 21f
+ rldicl. r8, r9, 48, 56
+ beq 22f
+ rldicl. r8, r9, 40, 56
+ beq 23f
+ addi r10, r10, 4
+ rldicl. r8, r9, 32, 56
+ beq 20f
+ rldicl. r8, r9, 24, 56
+ beq 21f
+ rldicl. r8, r9, 16, 56
+ beq 22f
+ rldicl. r8, r9, 8, 56
+#else
+#ifdef CONFIG_PPC64
+ rldicl. r8, r9, 8, 56
+ beq 20f
+ rldicl. r8, r9, 16, 56
+ beq 21f
+ rldicl. r8, r9, 24, 56
+ beq 22f
+ rldicl. r8, r9, 32, 56
+ beq 23f
+ addi r10, r10, 4
+#endif
+ rlwinm. r8, r9, 0, 0xff000000
+ beq 20f
+ rlwinm. r8, r9, 0, 0x00ff0000
+ beq 21f
+ rlwinm. r8, r9, 0, 0x0000ff00
+ beq 22f
+#endif /* CPU_LITTLE_ENDIAN */
+23: subf r3, r3, r10
+ addi r3, r3, 3
+ blr
+22: subf r3, r3, r10
+ addi r3, r3, 2
+ blr
+21: subf r3, r3, r10
+ addi r3, r3, 1
+ blr
+19: addi r10, r10, (SZL - 1)
+20: subf r3, r3, r10
+ blr
+
+1: lbz r9, SZL(r10)
+ addi r10, r10, 1
+ cmpwi cr1, r9, 0
+ andi. r9, r10, (SZL - 1)
+ beq cr1, 19b
+ bne 1b
+ b 2b
+EXPORT_SYMBOL(strlen)
--
2.13.3
^ permalink raw reply related [flat|nested] 5+ messages in thread