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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-24 13:39:17 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-24 13:39:17 -0400
commit793ae77469121227cd910c4b99f24be1de34bcca (patch)
treeca8b6bbafab35c5c1099c54696c36dc0b8c17cf7 /include/asm-i386
parent59a49e38711a146dc0bef4837c825b5422335460 (diff)
Add "memory" clobbers to the x86 inline asm of strncmp and friends
They don't actually clobber memory, but gcc doesn't even know they _read_ memory, so can apparently re-order memory accesses around them. Which obviously does the wrong thing if the memory access happens to change the memory that the compare function is accessing.. Verified to fix a strange boot problem by Jens Axboe.
Diffstat (limited to 'include/asm-i386')
-rw-r--r--include/asm-i386/string.h32
1 files changed, 22 insertions, 10 deletions
diff --git a/include/asm-i386/string.h b/include/asm-i386/string.h
index 6a78ac58c194..02c8f5d22065 100644
--- a/include/asm-i386/string.h
+++ b/include/asm-i386/string.h
@@ -116,7 +116,8 @@ __asm__ __volatile__(
116 "orb $1,%%al\n" 116 "orb $1,%%al\n"
117 "3:" 117 "3:"
118 :"=a" (__res), "=&S" (d0), "=&D" (d1) 118 :"=a" (__res), "=&S" (d0), "=&D" (d1)
119 :"1" (cs),"2" (ct)); 119 :"1" (cs),"2" (ct)
120 :"memory");
120return __res; 121return __res;
121} 122}
122 123
@@ -138,8 +139,9 @@ __asm__ __volatile__(
138 "3:\tsbbl %%eax,%%eax\n\t" 139 "3:\tsbbl %%eax,%%eax\n\t"
139 "orb $1,%%al\n" 140 "orb $1,%%al\n"
140 "4:" 141 "4:"
141 :"=a" (__res), "=&S" (d0), "=&D" (d1), "=&c" (d2) 142 :"=a" (__res), "=&S" (d0), "=&D" (d1), "=&c" (d2)
142 :"1" (cs),"2" (ct),"3" (count)); 143 :"1" (cs),"2" (ct),"3" (count)
144 :"memory");
143return __res; 145return __res;
144} 146}
145 147
@@ -158,7 +160,9 @@ __asm__ __volatile__(
158 "movl $1,%1\n" 160 "movl $1,%1\n"
159 "2:\tmovl %1,%0\n\t" 161 "2:\tmovl %1,%0\n\t"
160 "decl %0" 162 "decl %0"
161 :"=a" (__res), "=&S" (d0) : "1" (s),"0" (c)); 163 :"=a" (__res), "=&S" (d0)
164 :"1" (s),"0" (c)
165 :"memory");
162return __res; 166return __res;
163} 167}
164 168
@@ -175,7 +179,9 @@ __asm__ __volatile__(
175 "leal -1(%%esi),%0\n" 179 "leal -1(%%esi),%0\n"
176 "2:\ttestb %%al,%%al\n\t" 180 "2:\ttestb %%al,%%al\n\t"
177 "jne 1b" 181 "jne 1b"
178 :"=g" (__res), "=&S" (d0), "=&a" (d1) :"0" (0),"1" (s),"2" (c)); 182 :"=g" (__res), "=&S" (d0), "=&a" (d1)
183 :"0" (0),"1" (s),"2" (c)
184 :"memory");
179return __res; 185return __res;
180} 186}
181 187
@@ -189,7 +195,9 @@ __asm__ __volatile__(
189 "scasb\n\t" 195 "scasb\n\t"
190 "notl %0\n\t" 196 "notl %0\n\t"
191 "decl %0" 197 "decl %0"
192 :"=c" (__res), "=&D" (d0) :"1" (s),"a" (0), "0" (0xffffffffu)); 198 :"=c" (__res), "=&D" (d0)
199 :"1" (s),"a" (0), "0" (0xffffffffu)
200 :"memory");
193return __res; 201return __res;
194} 202}
195 203
@@ -333,7 +341,9 @@ __asm__ __volatile__(
333 "je 1f\n\t" 341 "je 1f\n\t"
334 "movl $1,%0\n" 342 "movl $1,%0\n"
335 "1:\tdecl %0" 343 "1:\tdecl %0"
336 :"=D" (__res), "=&c" (d0) : "a" (c),"0" (cs),"1" (count)); 344 :"=D" (__res), "=&c" (d0)
345 :"a" (c),"0" (cs),"1" (count)
346 :"memory");
337return __res; 347return __res;
338} 348}
339 349
@@ -369,7 +379,7 @@ __asm__ __volatile__(
369 "je 2f\n\t" 379 "je 2f\n\t"
370 "stosb\n" 380 "stosb\n"
371 "2:" 381 "2:"
372 : "=&c" (d0), "=&D" (d1) 382 :"=&c" (d0), "=&D" (d1)
373 :"a" (c), "q" (count), "0" (count/4), "1" ((long) s) 383 :"a" (c), "q" (count), "0" (count/4), "1" ((long) s)
374 :"memory"); 384 :"memory");
375return (s); 385return (s);
@@ -392,7 +402,8 @@ __asm__ __volatile__(
392 "jne 1b\n" 402 "jne 1b\n"
393 "3:\tsubl %2,%0" 403 "3:\tsubl %2,%0"
394 :"=a" (__res), "=&d" (d0) 404 :"=a" (__res), "=&d" (d0)
395 :"c" (s),"1" (count)); 405 :"c" (s),"1" (count)
406 :"memory");
396return __res; 407return __res;
397} 408}
398/* end of additional stuff */ 409/* end of additional stuff */
@@ -473,7 +484,8 @@ static inline void * memscan(void * addr, int c, size_t size)
473 "dec %%edi\n" 484 "dec %%edi\n"
474 "1:" 485 "1:"
475 : "=D" (addr), "=c" (size) 486 : "=D" (addr), "=c" (size)
476 : "0" (addr), "1" (size), "a" (c)); 487 : "0" (addr), "1" (size), "a" (c)
488 : "memory");
477 return addr; 489 return addr;
478} 490}
479 491