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.
This commit is contained in:
Linus Torvalds 2005-06-24 10:39:17 -07:00
Родитель 59a49e3871
Коммит 793ae77469
1 изменённых файлов: 22 добавлений и 10 удалений

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@ -116,7 +116,8 @@ __asm__ __volatile__(
"orb $1,%%al\n"
"3:"
:"=a" (__res), "=&S" (d0), "=&D" (d1)
:"1" (cs),"2" (ct));
:"1" (cs),"2" (ct)
:"memory");
return __res;
}
@ -138,8 +139,9 @@ __asm__ __volatile__(
"3:\tsbbl %%eax,%%eax\n\t"
"orb $1,%%al\n"
"4:"
:"=a" (__res), "=&S" (d0), "=&D" (d1), "=&c" (d2)
:"1" (cs),"2" (ct),"3" (count));
:"=a" (__res), "=&S" (d0), "=&D" (d1), "=&c" (d2)
:"1" (cs),"2" (ct),"3" (count)
:"memory");
return __res;
}
@ -158,7 +160,9 @@ __asm__ __volatile__(
"movl $1,%1\n"
"2:\tmovl %1,%0\n\t"
"decl %0"
:"=a" (__res), "=&S" (d0) : "1" (s),"0" (c));
:"=a" (__res), "=&S" (d0)
:"1" (s),"0" (c)
:"memory");
return __res;
}
@ -175,7 +179,9 @@ __asm__ __volatile__(
"leal -1(%%esi),%0\n"
"2:\ttestb %%al,%%al\n\t"
"jne 1b"
:"=g" (__res), "=&S" (d0), "=&a" (d1) :"0" (0),"1" (s),"2" (c));
:"=g" (__res), "=&S" (d0), "=&a" (d1)
:"0" (0),"1" (s),"2" (c)
:"memory");
return __res;
}
@ -189,7 +195,9 @@ __asm__ __volatile__(
"scasb\n\t"
"notl %0\n\t"
"decl %0"
:"=c" (__res), "=&D" (d0) :"1" (s),"a" (0), "0" (0xffffffffu));
:"=c" (__res), "=&D" (d0)
:"1" (s),"a" (0), "0" (0xffffffffu)
:"memory");
return __res;
}
@ -333,7 +341,9 @@ __asm__ __volatile__(
"je 1f\n\t"
"movl $1,%0\n"
"1:\tdecl %0"
:"=D" (__res), "=&c" (d0) : "a" (c),"0" (cs),"1" (count));
:"=D" (__res), "=&c" (d0)
:"a" (c),"0" (cs),"1" (count)
:"memory");
return __res;
}
@ -369,7 +379,7 @@ __asm__ __volatile__(
"je 2f\n\t"
"stosb\n"
"2:"
: "=&c" (d0), "=&D" (d1)
:"=&c" (d0), "=&D" (d1)
:"a" (c), "q" (count), "0" (count/4), "1" ((long) s)
:"memory");
return (s);
@ -392,7 +402,8 @@ __asm__ __volatile__(
"jne 1b\n"
"3:\tsubl %2,%0"
:"=a" (__res), "=&d" (d0)
:"c" (s),"1" (count));
:"c" (s),"1" (count)
:"memory");
return __res;
}
/* end of additional stuff */
@ -473,7 +484,8 @@ static inline void * memscan(void * addr, int c, size_t size)
"dec %%edi\n"
"1:"
: "=D" (addr), "=c" (size)
: "0" (addr), "1" (size), "a" (c));
: "0" (addr), "1" (size), "a" (c)
: "memory");
return addr;
}