[PATCH v3 6/9] microblaze: use generic strncpy/strnlen from_user

Arnd Bergmann
2021-07-22T12:49:38Z

From: Arnd Bergmann <arnd@arndb.de>

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

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
arch/microblaze/Kconfig | 2 +
arch/microblaze/include/asm/uaccess.h | 19 +----
arch/microblaze/kernel/microblaze_ksyms.c | 3 -
arch/microblaze/lib/uaccess_old.S | 90 -----------------------
4 files changed, 4 insertions(+), 110 deletions(-)

diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
index 14a67a42fcae..10dfa7b4feff 100644
--- a/arch/microblaze/Kconfig
+++ b/arch/microblaze/Kconfig
@@ -21,6 +21,8 @@ config MICROBLAZE
select GENERIC_IRQ_SHOW
select GENERIC_PCI_IOMAP
select GENERIC_SCHED_CLOCK
+ select GENERIC_STRNCPY_FROM_USER
+ select GENERIC_STRNLEN_USER
select HAVE_ARCH_HASH
select HAVE_ARCH_KGDB
select HAVE_ARCH_SECCOMP
diff --git a/arch/microblaze/include/asm/uaccess.h b/arch/microblaze/include/asm/uaccess.h
index c44b59470e45..bbe39fe00461 100644
--- a/arch/microblaze/include/asm/uaccess.h
+++ b/arch/microblaze/include/asm/uaccess.h
@@ -296,28 +296,13 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long n)
/*
* Copy a null terminated string from userspace.
*/
-extern int __strncpy_user(char *to, const char __user *from, int len);
-
-static inline long
-strncpy_from_user(char *dst, const char __user *src, long count)
-{
- if (!access_ok(src, 1))
- return -EFAULT;
- return __strncpy_user(dst, src, count);
-}
+extern long strncpy_from_user(char *dst, const char __user *src, long count);

/*
* Return the size of a string (including the ending 0)
*
* Return 0 on exception, a value greater than N if too long
*/
-extern int __strnlen_user(const char __user *sstr, int len);
-
-static inline long strnlen_user(const char __user *src, long n)
-{
- if (!access_ok(src, 1))
- return 0;
- return __strnlen_user(src, n);
-}
+extern long strnlen_user(const char __user *sstr, int len);

#endif /* _ASM_MICROBLAZE_UACCESS_H */
diff --git a/arch/microblaze/kernel/microblaze_ksyms.c b/arch/microblaze/kernel/microblaze_ksyms.c
index 303aaf13573b..14e0f2100c41 100644
--- a/arch/microblaze/kernel/microblaze_ksyms.c
+++ b/arch/microblaze/kernel/microblaze_ksyms.c
@@ -25,9 +25,6 @@ EXPORT_SYMBOL(_mcount);
/*
* Assembly functions that may be used (directly or indirectly) by modules
*/
-EXPORT_SYMBOL(__copy_tofrom_user);
-EXPORT_SYMBOL(__strncpy_user);
-
#ifdef CONFIG_OPT_LIB_ASM
EXPORT_SYMBOL(memcpy);
EXPORT_SYMBOL(memmove);
diff --git a/arch/microblaze/lib/uaccess_old.S b/arch/microblaze/lib/uaccess_old.S
index eca290090038..dd5f3bfbc2c5 100644
--- a/arch/microblaze/lib/uaccess_old.S
+++ b/arch/microblaze/lib/uaccess_old.S
@@ -12,96 +12,6 @@
#include <linux/linkage.h>
#include <asm/page.h>

-/*
- * int __strncpy_user(char *to, char *from, int len);
- *
- * Returns:
- * -EFAULT for an exception
- * len if we hit the buffer limit
- * bytes copied
- */
-
- .text
-.globl __strncpy_user;
-.type __strncpy_user, @function
-.align 4;
-__strncpy_user:
-
- /*
- * r5 - to
- * r6 - from
- * r7 - len
- * r3 - temp count
- * r4 - temp val
- */
- beqid r7,3f
- addik r3,r7,0 /* temp_count = len */
-1:
- lbu r4,r6,r0
- beqid r4,2f
- sb r4,r5,r0
-
- addik r5,r5,1
- addik r6,r6,1 /* delay slot */
-
- addik r3,r3,-1
- bnei r3,1b /* break on len */
-2:
- rsubk r3,r3,r7 /* temp_count = len - temp_count */
-3:
- rtsd r15,8
- nop
- .size __strncpy_user, . - __strncpy_user
-
- .section .fixup, "ax"
- .align 2
-4:
- brid 3b
- addik r3,r0, -EFAULT
-
- .section __ex_table, "a"
- .word 1b,4b
-
-/*
- * int __strnlen_user(char __user *str, int maxlen);
- *
- * Returns:
- * 0 on error
- * maxlen + 1 if no NUL byte found within maxlen bytes
- * size of the string (including NUL byte)
- */
-
- .text
-.globl __strnlen_user;
-.type __strnlen_user, @function
-.align 4;
-__strnlen_user:
- beqid r6,3f
- addik r3,r6,0
-1:
- lbu r4,r5,r0
- beqid r4,2f /* break on NUL */
- addik r3,r3,-1 /* delay slot */
-
- bneid r3,1b
- addik r5,r5,1 /* delay slot */
-
- addik r3,r3,-1 /* for break on len */
-2:
- rsubk r3,r3,r6
-3:
- rtsd r15,8
- nop
- .size __strnlen_user, . - __strnlen_user
-
- .section .fixup,"ax"
-4:
- brid 3b
- addk r3,r0,r0
-
- .section __ex_table,"a"
- .word 1b,4b
-
/* Loop unrolling for __copy_tofrom_user */
#define COPY(offset) \
1: lwi r4 , r6, 0x0000 + offset; \
--
2.29.2