[PATCH v3 4/9] arc: use generic strncpy/strnlen from_user

Arnd Bergmann
2021-07-22T12:49:26Z

From: Arnd Bergmann <arnd@arndb.de>

Remove the arc implemenation of strncpy/strnlen and instead use the
generic versions. The arc version is fairly slow because it always does
byte accesses even for aligned data, and its checks for user_addr_max()
differ from the generic code.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
arch/arc/Kconfig | 2 +
arch/arc/include/asm/uaccess.h | 83 ++--------------------------------
arch/arc/mm/extable.c | 12 -----
3 files changed, 7 insertions(+), 90 deletions(-)

diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index d8f51eb8963b..64e5f9366401 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -27,6 +27,8 @@ config ARC
select GENERIC_PENDING_IRQ if SMP
select GENERIC_SCHED_CLOCK
select GENERIC_SMP_IDLE_THREAD
+ select GENERIC_STRNCPY_FROM_USER
+ select GENERIC_STRNLEN_USER
select HAVE_ARCH_KGDB
select HAVE_ARCH_TRACEHOOK
select HAVE_ARCH_TRANSPARENT_HUGEPAGE if ARC_MMU_V4
diff --git a/arch/arc/include/asm/uaccess.h b/arch/arc/include/asm/uaccess.h
index 3476348f361e..754a23f26736 100644
--- a/arch/arc/include/asm/uaccess.h
+++ b/arch/arc/include/asm/uaccess.h
@@ -655,96 +655,23 @@ static inline unsigned long __arc_clear_user(void __user *to, unsigned long n)
return res;
}

-static inline long
-__arc_strncpy_from_user(char *dst, const char __user *src, long count)
-{
- long res = 0;
- char val;
-
- if (!access_ok(src, 1))
- return -EFAULT;
-
- if (count == 0)
- return 0;
-
- __asm__ __volatile__(
- " mov lp_count, %5 \n"
- " lp 3f \n"
- "1: ldb.ab %3, [%2, 1] \n"
- " breq.d %3, 0, 3f \n"
- " stb.ab %3, [%1, 1] \n"
- " add %0, %0, 1 # Num of NON NULL bytes copied \n"
- "3: \n"
- " .section .fixup, \"ax\" \n"
- " .align 4 \n"
- "4: mov %0, %4 # sets @res as -EFAULT \n"
- " j 3b \n"
- " .previous \n"
- " .section __ex_table, \"a\" \n"
- " .align 4 \n"
- " .word 1b, 4b \n"
- " .previous \n"
- : "+r"(res), "+r"(dst), "+r"(src), "=r"(val)
- : "g"(-EFAULT), "r"(count)
- : "lp_count", "memory");
-
- return res;
-}
-
-static inline long __arc_strnlen_user(const char __user *s, long n)
-{
- long res, tmp1, cnt;
- char val;
-
- if (!access_ok(s, 1))
- return 0;
-
- __asm__ __volatile__(
- " mov %2, %1 \n"
- "1: ldb.ab %3, [%0, 1] \n"
- " breq.d %3, 0, 2f \n"
- " sub.f %2, %2, 1 \n"
- " bnz 1b \n"
- " sub %2, %2, 1 \n"
- "2: sub %0, %1, %2 \n"
- "3: ;nop \n"
- " .section .fixup, \"ax\" \n"
- " .align 4 \n"
- "4: mov %0, 0 \n"
- " j 3b \n"
- " .previous \n"
- " .section __ex_table, \"a\" \n"
- " .align 4 \n"
- " .word 1b, 4b \n"
- " .previous \n"
- : "=r"(res), "=r"(tmp1), "=r"(cnt), "=r"(val)
- : "0"(s), "1"(n)
- : "memory");
-
- return res;
-}
-
#ifndef CONFIG_CC_OPTIMIZE_FOR_SIZE

#define INLINE_COPY_TO_USER
#define INLINE_COPY_FROM_USER

#define __clear_user(d, n) __arc_clear_user(d, n)
-#define strncpy_from_user(d, s, n) __arc_strncpy_from_user(d, s, n)
-#define strnlen_user(s, n) __arc_strnlen_user(s, n)
#else
extern unsigned long arc_clear_user_noinline(void __user *to,
unsigned long n);
-extern long arc_strncpy_from_user_noinline (char *dst, const char __user *src,
- long count);
-extern long arc_strnlen_user_noinline(const char __user *src, long n);
-
#define __clear_user(d, n) arc_clear_user_noinline(d, n)
-#define strncpy_from_user(d, s, n) arc_strncpy_from_user_noinline(d, s, n)
-#define strnlen_user(s, n) arc_strnlen_user_noinline(s, n)
-
#endif

+extern long strncpy_from_user(char *dst, const char __user *src, long count);
+#define strncpy_from_user(d, s, n) strncpy_from_user(d, s, n)
+extern long strnlen_user(const char __user *src, long n);
+#define strnlen_user(s, n) strnlen_user(s, n)
+
#include <asm/segment.h>
#include <asm-generic/uaccess.h>

diff --git a/arch/arc/mm/extable.c b/arch/arc/mm/extable.c
index b06b09ddf924..4e14c4244ea2 100644
--- a/arch/arc/mm/extable.c
+++ b/arch/arc/mm/extable.c
@@ -32,16 +32,4 @@ unsigned long arc_clear_user_noinline(void __user *to,
}
EXPORT_SYMBOL(arc_clear_user_noinline);

-long arc_strncpy_from_user_noinline(char *dst, const char __user *src,
- long count)
-{
- return __arc_strncpy_from_user(dst, src, count);
-}
-EXPORT_SYMBOL(arc_strncpy_from_user_noinline);
-
-long arc_strnlen_user_noinline(const char __user *src, long n)
-{
- return __arc_strnlen_user(src, n);
-}
-EXPORT_SYMBOL(arc_strnlen_user_noinline);
#endif
--
2.29.2