Using strlen as a model, add length checking to create strnlen. Signed-off-by: Ken Steele <k...@tilera.com> Signed-off-by: Chris Metcalf <cmetc...@tilera.com> --- arch/tile/include/asm/string.h | 2 ++ arch/tile/lib/Makefile | 2 +- arch/tile/lib/strnlen_32.c | 49 ++++++++++++++++++++++++++++++++++++++++++ arch/tile/lib/strnlen_64.c | 48 +++++++++++++++++++++++++++++++++++++++++ 4 files changed, 100 insertions(+), 1 deletion(-) create mode 100644 arch/tile/lib/strnlen_32.c create mode 100644 arch/tile/lib/strnlen_64.c
diff --git a/arch/tile/include/asm/string.h b/arch/tile/include/asm/string.h index 7535cf1..92b271b 100644 --- a/arch/tile/include/asm/string.h +++ b/arch/tile/include/asm/string.h @@ -21,8 +21,10 @@ #define __HAVE_ARCH_MEMMOVE #define __HAVE_ARCH_STRCHR #define __HAVE_ARCH_STRLEN +#define __HAVE_ARCH_STRNLEN extern __kernel_size_t strlen(const char *); +extern __kernel_size_t strnlen(const char *, __kernel_size_t); extern char *strchr(const char *s, int c); extern void *memchr(const void *s, int c, size_t n); extern void *memset(void *, int, __kernel_size_t); diff --git a/arch/tile/lib/Makefile b/arch/tile/lib/Makefile index 985f598..5d84437 100644 --- a/arch/tile/lib/Makefile +++ b/arch/tile/lib/Makefile @@ -4,7 +4,7 @@ lib-y = cacheflush.o checksum.o cpumask.o delay.o uaccess.o \ memmove.o memcpy_$(BITS).o memchr_$(BITS).o memset_$(BITS).o \ - strchr_$(BITS).o strlen_$(BITS).o + strchr_$(BITS).o strlen_$(BITS).o strnlen_$(BITS).o ifeq ($(CONFIG_TILEGX),y) CFLAGS_REMOVE_memcpy_user_64.o = -fno-omit-frame-pointer diff --git a/arch/tile/lib/strnlen_32.c b/arch/tile/lib/strnlen_32.c new file mode 100644 index 0000000..4490cf9 --- /dev/null +++ b/arch/tile/lib/strnlen_32.c @@ -0,0 +1,49 @@ +/* + * Copyright 2013 Tilera Corporation. All Rights Reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation, version 2. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or + * NON INFRINGEMENT. See the GNU General Public License for + * more details. + */ + +#include <linux/types.h> +#include <linux/string.h> +#include <linux/module.h> + +size_t strnlen(const char *s, size_t count) +{ + /* Get an aligned pointer. */ + const uintptr_t s_int = (uintptr_t) s; + const uint32_t *p = (const uint32_t *)(s_int & -4); + size_t bytes_read = sizeof(*p) - (s_int & (sizeof(*p) - 1)); + size_t len; + uint32_t v, bits; + + /* Avoid page fault risk by not reading any bytes when count is 0. */ + if (count == 0) + return 0; + + /* Read the first word, but force bytes before the string to be nonzero. + * This expression works because we know shift counts are taken mod 32. + */ + v = *p | ((1 << (s_int << 3)) - 1); + + while ((bits = __insn_seqb(v, 0)) == 0) { + if (bytes_read >= count) { + /* Read COUNT bytes and didn't find the terminator. */ + return count; + } + v = *++p; + bytes_read += sizeof(v); + } + + len = ((const char *) p) + (__insn_ctz(bits) >> 3) - s; + return (len < count ? len : count); +} +EXPORT_SYMBOL(strnlen); diff --git a/arch/tile/lib/strnlen_64.c b/arch/tile/lib/strnlen_64.c new file mode 100644 index 0000000..2e8de6a --- /dev/null +++ b/arch/tile/lib/strnlen_64.c @@ -0,0 +1,48 @@ +/* + * Copyright 2013 Tilera Corporation. All Rights Reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation, version 2. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or + * NON INFRINGEMENT. See the GNU General Public License for + * more details. + */ + +#include <linux/types.h> +#include <linux/string.h> +#include <linux/module.h> +#include "string-endian.h" + +size_t strnlen(const char *s, size_t count) +{ + /* Get an aligned pointer. */ + const uintptr_t s_int = (uintptr_t) s; + const uint64_t *p = (const uint64_t *)(s_int & -8); + size_t bytes_read = sizeof(*p) - (s_int & (sizeof(*p) - 1)); + size_t len; + uint64_t v, bits; + + /* Avoid page fault risk by not reading any bytes when count is 0. */ + if (count == 0) + return 0; + + /* Read and MASK the first word. */ + v = *p | MASK(s_int); + + while ((bits = __insn_v1cmpeqi(v, 0)) == 0) { + if (bytes_read >= count) { + /* Read COUNT bytes and didn't find the terminator. */ + return count; + } + v = *++p; + bytes_read += sizeof(v); + } + + len = ((const char *) p) + (CFZ(bits) >> 3) - s; + return (len < count ? len : count); +} +EXPORT_SYMBOL(strnlen); -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/