[PATCH AUTOSEL 6.10 34/70] riscv: Omit optimized string routines when using KASAN

Sasha Levin
2024-10-04T18:23:07Z

From: Samuel Holland <samuel.holland@sifive.com>

[ Upstream commit 58ff537109ac863d4ec83baf8413b17dcc10101c ]

The optimized string routines are implemented in assembly, so they are
not instrumented for use with KASAN. Fall back to the C version of the
routines in order to improve KASAN coverage. This fixes the
kasan_strings() unit test.

Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Tested-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20240801033725.28816-2-samuel.holland@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/riscv/include/asm/string.h | 2 ++
arch/riscv/kernel/riscv_ksyms.c | 3 ---
arch/riscv/lib/Makefile | 2 ++
arch/riscv/lib/strcmp.S | 1 +
arch/riscv/lib/strlen.S | 1 +
arch/riscv/lib/strncmp.S | 1 +
arch/riscv/purgatory/Makefile | 2 ++
7 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/include/asm/string.h b/arch/riscv/include/asm/string.h
index a96b1fea24fe4..5ba77f60bf0b5 100644
--- a/arch/riscv/include/asm/string.h
+++ b/arch/riscv/include/asm/string.h
@@ -19,6 +19,7 @@ extern asmlinkage void *__memcpy(void *, const void *, size_t);
extern asmlinkage void *memmove(void *, const void *, size_t);
extern asmlinkage void *__memmove(void *, const void *, size_t);

+#if !(defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS))
#define __HAVE_ARCH_STRCMP
extern asmlinkage int strcmp(const char *cs, const char *ct);

@@ -27,6 +28,7 @@ extern asmlinkage __kernel_size_t strlen(const char *);

#define __HAVE_ARCH_STRNCMP
extern asmlinkage int strncmp(const char *cs, const char *ct, size_t count);
+#endif

/* For those files which don't want to check by kasan. */
#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
diff --git a/arch/riscv/kernel/riscv_ksyms.c b/arch/riscv/kernel/riscv_ksyms.c
index a72879b4249a5..5ab1c7e1a6ed5 100644
--- a/arch/riscv/kernel/riscv_ksyms.c
+++ b/arch/riscv/kernel/riscv_ksyms.c
@@ -12,9 +12,6 @@
EXPORT_SYMBOL(memset);
EXPORT_SYMBOL(memcpy);
EXPORT_SYMBOL(memmove);
-EXPORT_SYMBOL(strcmp);
-EXPORT_SYMBOL(strlen);
-EXPORT_SYMBOL(strncmp);
EXPORT_SYMBOL(__memset);
EXPORT_SYMBOL(__memcpy);
EXPORT_SYMBOL(__memmove);
diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile
index bd6e6c1b0497b..07a7cc46ac740 100644
--- a/arch/riscv/lib/Makefile
+++ b/arch/riscv/lib/Makefile
@@ -3,9 +3,11 @@ lib-y += delay.o
lib-y += memcpy.o
lib-y += memset.o
lib-y += memmove.o
+ifeq ($(CONFIG_KASAN_GENERIC)$(CONFIG_KASAN_SW_TAGS),)
lib-y += strcmp.o
lib-y += strlen.o
lib-y += strncmp.o
+endif
lib-y += csum.o
ifeq ($(CONFIG_MMU), y)
lib-$(CONFIG_RISCV_ISA_V) += uaccess_vector.o
diff --git a/arch/riscv/lib/strcmp.S b/arch/riscv/lib/strcmp.S
index 687b2bea5c438..542301a67a2ff 100644
--- a/arch/riscv/lib/strcmp.S
+++ b/arch/riscv/lib/strcmp.S
@@ -120,3 +120,4 @@ strcmp_zbb:
.option pop
#endif
SYM_FUNC_END(strcmp)
+EXPORT_SYMBOL(strcmp)
diff --git a/arch/riscv/lib/strlen.S b/arch/riscv/lib/strlen.S
index 8ae3064e45ff0..962983b73251e 100644
--- a/arch/riscv/lib/strlen.S
+++ b/arch/riscv/lib/strlen.S
@@ -131,3 +131,4 @@ strlen_zbb:
#endif
SYM_FUNC_END(strlen)
SYM_FUNC_ALIAS(__pi_strlen, strlen)
+EXPORT_SYMBOL(strlen)
diff --git a/arch/riscv/lib/strncmp.S b/arch/riscv/lib/strncmp.S
index aba5b3148621d..0f359ea2f55b2 100644
--- a/arch/riscv/lib/strncmp.S
+++ b/arch/riscv/lib/strncmp.S
@@ -136,3 +136,4 @@ strncmp_zbb:
.option pop
#endif
SYM_FUNC_END(strncmp)
+EXPORT_SYMBOL(strncmp)
diff --git a/arch/riscv/purgatory/Makefile b/arch/riscv/purgatory/Makefile
index f11945ee24903..fb9c917c9b457 100644
--- a/arch/riscv/purgatory/Makefile
+++ b/arch/riscv/purgatory/Makefile
@@ -1,7 +1,9 @@
# SPDX-License-Identifier: GPL-2.0

purgatory-y := purgatory.o sha256.o entry.o string.o ctype.o memcpy.o memset.o
+ifeq ($(CONFIG_KASAN_GENERIC)$(CONFIG_KASAN_SW_TAGS),)
purgatory-y += strcmp.o strlen.o strncmp.o
+endif

targets += $(purgatory-y)
PURGATORY_OBJS = $(addprefix $(obj)/,$(purgatory-y))
--
2.43.0