[PATCH 2/2] powerpc: Use the new generic strncpy_from_user() and strnlen_user()
Paul Mackerras
paulus at samba.org
Mon May 28 13:03:47 EST 2012
This is much the same as for SPARC except that we can do the find_zero()
function more efficiently using the count-leading-zeroes instructions.
Tested on 32-bit and 64-bit PowerPC.
Signed-off-by: Paul Mackerras <paulus at samba.org>
---
I'm sending this in without Ben H's ack as he is away for a few weeks for
medical reasons.
arch/powerpc/Kconfig | 2 ++
arch/powerpc/include/asm/uaccess.h | 41 ++++----------------------
arch/powerpc/include/asm/word-at-a-time.h | 41 ++++++++++++++++++++++++++
arch/powerpc/kernel/ppc_ksyms.c | 2 --
arch/powerpc/lib/string.S | 45 -----------------------------
5 files changed, 48 insertions(+), 83 deletions(-)
create mode 100644 arch/powerpc/include/asm/word-at-a-time.h
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 00b9874..050cb37 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -135,6 +135,8 @@ config PPC
select GENERIC_CMOS_UPDATE
select GENERIC_TIME_VSYSCALL
select GENERIC_CLOCKEVENTS
+ select GENERIC_STRNCPY_FROM_USER
+ select GENERIC_STRNLEN_USER
config EARLY_PRINTK
bool
diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index bd0fb84..17bb40c 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -40,6 +40,8 @@
#define segment_eq(a, b) ((a).seg == (b).seg)
+#define user_addr_max() (get_fs().seg)
+
#ifdef __powerpc64__
/*
* This check is sufficient because there is a large enough
@@ -453,42 +455,9 @@ static inline unsigned long clear_user(void __user *addr, unsigned long size)
return size;
}
-extern int __strncpy_from_user(char *dst, const char __user *src, long count);
-
-static inline long strncpy_from_user(char *dst, const char __user *src,
- long count)
-{
- might_sleep();
- if (likely(access_ok(VERIFY_READ, src, 1)))
- return __strncpy_from_user(dst, src, count);
- return -EFAULT;
-}
-
-/*
- * Return the size of a string (including the ending 0)
- *
- * Return 0 for error
- */
-extern int __strnlen_user(const char __user *str, long len, unsigned long top);
-
-/*
- * Returns the length of the string at str (including the null byte),
- * or 0 if we hit a page we can't access,
- * or something > len if we didn't find a null byte.
- *
- * The `top' parameter to __strnlen_user is to make sure that
- * we can never overflow from the user area into kernel space.
- */
-static inline int strnlen_user(const char __user *str, long len)
-{
- unsigned long top = current->thread.fs.seg;
-
- if ((unsigned long)str > top)
- return 0;
- return __strnlen_user(str, len, top);
-}
-
-#define strlen_user(str) strnlen_user((str), 0x7ffffffe)
+extern long strncpy_from_user(char *dst, const char __user *src, long count);
+extern __must_check long strlen_user(const char __user *str);
+extern __must_check long strnlen_user(const char __user *str, long n);
#endif /* __ASSEMBLY__ */
#endif /* __KERNEL__ */
diff --git a/arch/powerpc/include/asm/word-at-a-time.h b/arch/powerpc/include/asm/word-at-a-time.h
new file mode 100644
index 0000000..d0b6d4a
--- /dev/null
+++ b/arch/powerpc/include/asm/word-at-a-time.h
@@ -0,0 +1,41 @@
+#ifndef _ASM_WORD_AT_A_TIME_H
+#define _ASM_WORD_AT_A_TIME_H
+
+/*
+ * Word-at-a-time interfaces for PowerPC.
+ */
+
+#include <linux/kernel.h>
+#include <asm/asm-compat.h>
+
+struct word_at_a_time {
+ const unsigned long high_bits, low_bits;
+};
+
+#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0xfe) + 1, REPEAT_BYTE(0x7f) }
+
+/* Bit set in the bytes that have a zero */
+static inline long prep_zero_mask(unsigned long val, unsigned long rhs, const struct word_at_a_time *c)
+{
+ unsigned long mask = (val & c->low_bits) + c->low_bits;
+ return ~(mask | rhs);
+}
+
+#define create_zero_mask(mask) (mask)
+
+static inline long find_zero(unsigned long mask)
+{
+ long leading_zero_bits;
+
+ asm (PPC_CNTLZL "%0,%1" : "=r" (leading_zero_bits) : "r" (mask));
+ return leading_zero_bits >> 3;
+}
+
+static inline bool has_zero(unsigned long val, unsigned long *data, const struct word_at_a_time *c)
+{
+ unsigned long rhs = val | c->low_bits;
+ *data = rhs;
+ return (val + c->high_bits) & ~rhs;
+}
+
+#endif /* _ASM_WORD_AT_A_TIME_H */
diff --git a/arch/powerpc/kernel/ppc_ksyms.c b/arch/powerpc/kernel/ppc_ksyms.c
index d1f2aaf..3e40315 100644
--- a/arch/powerpc/kernel/ppc_ksyms.c
+++ b/arch/powerpc/kernel/ppc_ksyms.c
@@ -85,8 +85,6 @@ EXPORT_SYMBOL(csum_tcpudp_magic);
EXPORT_SYMBOL(__copy_tofrom_user);
EXPORT_SYMBOL(__clear_user);
-EXPORT_SYMBOL(__strncpy_from_user);
-EXPORT_SYMBOL(__strnlen_user);
EXPORT_SYMBOL(copy_page);
#if defined(CONFIG_PCI) && defined(CONFIG_PPC32)
diff --git a/arch/powerpc/lib/string.S b/arch/powerpc/lib/string.S
index 455881a..093d631 100644
--- a/arch/powerpc/lib/string.S
+++ b/arch/powerpc/lib/string.S
@@ -160,48 +160,3 @@ _GLOBAL(__clear_user)
PPC_LONG 1b,91b
PPC_LONG 8b,92b
.text
-
-_GLOBAL(__strncpy_from_user)
- addi r6,r3,-1
- addi r4,r4,-1
- cmpwi 0,r5,0
- beq 2f
- mtctr r5
-1: lbzu r0,1(r4)
- cmpwi 0,r0,0
- stbu r0,1(r6)
- bdnzf 2,1b /* dec ctr, branch if ctr != 0 && !cr0.eq */
- beq 3f
-2: addi r6,r6,1
-3: subf r3,r3,r6
- blr
-99: li r3,-EFAULT
- blr
-
- .section __ex_table,"a"
- PPC_LONG 1b,99b
- .text
-
-/* r3 = str, r4 = len (> 0), r5 = top (highest addr) */
-_GLOBAL(__strnlen_user)
- addi r7,r3,-1
- subf r6,r7,r5 /* top+1 - str */
- cmplw 0,r4,r6
- bge 0f
- mr r6,r4
-0: mtctr r6 /* ctr = min(len, top - str) */
-1: lbzu r0,1(r7) /* get next byte */
- cmpwi 0,r0,0
- bdnzf 2,1b /* loop if --ctr != 0 && byte != 0 */
- addi r7,r7,1
- subf r3,r3,r7 /* number of bytes we have looked at */
- beqlr /* return if we found a 0 byte */
- cmpw 0,r3,r4 /* did we look at all len bytes? */
- blt 99f /* if not, must have hit top */
- addi r3,r4,1 /* return len + 1 to indicate no null found */
- blr
-99: li r3,0 /* bad address, return 0 */
- blr
-
- .section __ex_table,"a"
- PPC_LONG 1b,99b
--
1.7.10.rc3.219.g53414
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