Blackfin arch: fix some bugs in lib/string.h functions found by our string testing modules

 - use ints for the return value rather than char since we actually return
   an int and we dont want it improperly being sign extended during the reload
   http://blackfin.uclinux.org/gf/project/uclinux-dist/tracker/?action=TrackerItemEdit&tracker_item_id=3525

 - if src is shorter than the requested number of copy bytes, we need to null
   pad the rest
   http://blackfin.uclinux.org/gf/project/uclinux-dist/tracker/?action=TrackerItemEdit&tracker_item_id=3524

 - mark these as __volatile__ and add memory to the clobber list so gcc does
   not optimize buffers around on us we may be using

 - rewrite asm code to be readable/maintainable

Signed-off-by: Mike Frysinger <michael.frysinger@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

1 files changed, 80 insertions, 49 deletions

diff --git a/include/asm-blackfin/string.h b/include/asm-blackfin/string.h
index 6f1eb7d6d3cb..e8ada91ab002 100644
--- a/include/asm-blackfin/string.h
+++ b/include/asm-blackfin/string.h
@@ -9,13 +9,16 @@ extern inline char *strcpy(char *dest, const char *src)
         char *xdest = dest;
         char temp = 0;
 
-        __asm__ __volatile__
-            ("1:\t%2 = B [%1++] (Z);\n\t"
-             "B [%0++] = %2;\n\t"
-             "CC = %2;\n\t"
-        "if cc jump 1b (bp);\n"
-        : "+&a" (dest), "+&a" (src), "=&d" (temp)
-             ::"memory", "CC");
+        __asm__ __volatile__ (
+                "1:"
+                "%2 = B [%1++] (Z);"
+                "B [%0++] = %2;"
+                "CC = %2;"
+                "if cc jump 1b (bp);"
+                : "+&a" (dest), "+&a" (src), "=&d" (temp)
+                :
+                : "memory", "CC");
+
         return xdest;
 }
 
@@ -28,37 +31,56 @@ extern inline char *strncpy(char *dest, const char *src, size_t n)
         if (n == 0)
                 return xdest;
 
-        __asm__ __volatile__
-            ("1:\t%3 = B [%1++] (Z);\n\t"
-             "B [%0++] = %3;\n\t"
-             "CC = %3;\n\t"
-             "if ! cc jump 2f;\n\t"
-             "%2 += -1;\n\t"
-             "CC = %2 == 0;\n\t"
-             "if ! cc jump 1b (bp);\n"
-        "2:\n"
-        : "+&a" (dest), "+&a" (src), "+&da" (n), "=&d" (temp)
-             ::"memory", "CC");
+        __asm__ __volatile__ (
+                "1:"
+                "%3 = B [%1++] (Z);"
+                "B [%0++] = %3;"
+                "CC = %3;"
+                "if ! cc jump 2f;"
+                "%2 += -1;"
+                "CC = %2 == 0;"
+                "if ! cc jump 1b (bp);"
+                "jump 4f;"
+                "2:"
+                /* if src is shorter than n, we need to null pad bytes now */
+                "%3 = 0;"
+                "3:"
+                "%2 += -1;"
+                "CC = %2 == 0;"
+                "if cc jump 4f;"
+                "B [%0++] = %3;"
+                "jump 3b;"
+                "4:"
+                : "+&a" (dest), "+&a" (src), "+&da" (n), "=&d" (temp)
+                :
+                : "memory", "CC");
+
         return xdest;
 }
 
 #define __HAVE_ARCH_STRCMP
 extern inline int strcmp(const char *cs, const char *ct)
 {
-        char __res1, __res2;
-
-        __asm__
-       ("1:\t%2 = B[%0++] (Z);\n\t" /* get *cs */
-                "%3 = B[%1++] (Z);\n\t" /* get *ct */
-                "CC = %2 == %3;\n\t"    /* compare a byte */
-                "if ! cc jump 2f;\n\t"  /* not equal, break out */
-                "CC = %2;\n\t"  /* at end of cs? */
-                "if cc jump 1b (bp);\n\t"       /* no, keep going */
-                "jump.s 3f;\n"  /* strings are equal */
-                "2:\t%2 = %2 - %3;\n"   /* *cs - *ct */
-        "3:\n"
-        : "+&a" (cs), "+&a" (ct), "=&d" (__res1), "=&d" (__res2)
-      : :       "CC");
+        /* need to use int's here so the char's in the assembly don't get
+         * sign extended incorrectly when we don't want them to be
+         */
+        int __res1, __res2;
+
+        __asm__ __volatile__ (
+                "1:"
+                "%2 = B[%0++] (Z);"      /* get *cs */
+                "%3 = B[%1++] (Z);"      /* get *ct */
+                "CC = %2 == %3;"         /* compare a byte */
+                "if ! cc jump 2f;"       /* not equal, break out */
+                "CC = %2;"               /* at end of cs? */
+                "if cc jump 1b (bp);"    /* no, keep going */
+                "jump.s 3f;"             /* strings are equal */
+                "2:"
+                "%2 = %2 - %3;"          /* *cs - *ct */
+                "3:"
+                : "+&a" (cs), "+&a" (ct), "=&d" (__res1), "=&d" (__res2)
+                :
+                : "memory", "CC");
 
         return __res1;
 }
@@ -66,26 +88,35 @@ extern inline int strcmp(const char *cs, const char *ct)
 #define __HAVE_ARCH_STRNCMP
 extern inline int strncmp(const char *cs, const char *ct, size_t count)
 {
-        char __res1, __res2;
+        /* need to use int's here so the char's in the assembly don't get
+         * sign extended incorrectly when we don't want them to be
+         */
+        int __res1, __res2;
 
         if (!count)
                 return 0;
-        __asm__
-       ("1:\t%3 = B[%0++] (Z);\n\t"        /* get *cs */
-                "%4 = B[%1++] (Z);\n\t" /* get *ct */
-                "CC = %3 == %4;\n\t"    /* compare a byte */
-                "if ! cc jump 3f;\n\t"  /* not equal, break out */
-                "CC = %3;\n\t"  /* at end of cs? */
-                "if ! cc jump 4f;\n\t"  /* yes, all done */
-                "%2 += -1;\n\t" /* no, adjust count */
-        "CC = %2 == 0;\n\t"
-        "if ! cc jump 1b;\n"                 /* more to do, keep going */
-                "2:\t%3 = 0;\n\t"       /* strings are equal */
-        "jump.s    4f;\n"
-        "3:\t%3 = %3 - %4;\n"          /* *cs - *ct */
-        "4:"
-        : "+&a" (cs), "+&a" (ct), "+&da" (count), "=&d" (__res1), "=&d" (__res2)
-      : :       "CC");
+
+        __asm__ __volatile__ (
+                "1:"
+                "%3 = B[%0++] (Z);"      /* get *cs */
+                "%4 = B[%1++] (Z);"      /* get *ct */
+                "CC = %3 == %4;"         /* compare a byte */
+                "if ! cc jump 3f;"       /* not equal, break out */
+                "CC = %3;"               /* at end of cs? */
+                "if ! cc jump 4f;"       /* yes, all done */
+                "%2 += -1;"              /* no, adjust count */
+                "CC = %2 == 0;"
+                "if ! cc jump 1b;"       /* more to do, keep going */
+                "2:"
+                "%3 = 0;"                /* strings are equal */
+                "jump.s 4f;"
+                "3:"
+                "%3 = %3 - %4;"          /* *cs - *ct */
+                "4:"
+                : "+&a" (cs), "+&a" (ct), "+&da" (count), "=&d" (__res1), "=&d" (__res2)
+                :
+                : "memory", "CC");
+
         return __res1;
 }