numactl: fix libnuma on big-endian 64-bit systems

The read-mask function assumes that it is running in 32-bit mode, by addressing the bitmask as a series of int values, instead of longs. This is broken as can easily be reproduced by running numademo on a bit-endian 64-bit system.

Changing the addressing to use 'long' values fixes the problem.

Reported-by Mijo Safradin <[email protected]>

---

Note: the set_nodemask_size() function is broken as well, it seems to always set the nodemask size to "17" with the s2nbits implementation. The fallback path in there looks correct.

libnuma.c +5 -5

@@ -392,9 +372,9 @@ read_mask(char *s, struct bitmask *bmp)
 {
 	char *end = s;
 	char *prevend;
-	unsigned long *start = bmp->maskp;
-	unsigned long *p = start;
-	unsigned long *q;
+	unsigned int *start = (unsigned int *)bmp->maskp;
+	unsigned int *p = start;
+	unsigned int *q;
 	unsigned int i;
 	unsigned int n = 0;
 

@@ -431,14 +411,14 @@
 	}
 
 	/* Poor mans fls() */
-	for(i = sizeof(long) * 8 - 1; i >= 0; i--)
+	for(i = 31; i >= 0; i--)
 		if (test_bit(i, start + n))
 			break;
 
 	/*
 	 * Return the last bit set
 	 */
-	return ((sizeof(unsigned long)*8) * n) + i;
+	return ((sizeof(unsigned int)*8) * n) + i;
 }
 
 /*

Quoted 6 lines · Arnd Bergmann

The read-mask function assumes that it is running in 32-bit mode, by addressing the bitmask as a series of int values, instead of longs. This is broken as can easily be reproduced by running numademo on a bit-endian 64-bit system.

Changing the addressing to use 'long' values fixes the problem.

Hi, Arnd:

Not sure what you mean here. If the patch below is a proposed fix [I don't see a 'Signed-off-by:", but maybe not needed for libnuma patches?], the description above doesn't match the code. Looks like you're changing the addressing FROM 'long' values to use 'int' values so that the size is compatible between 32- and 64-bits. Or is that a reverse patch/diff below?

The read-mask function assumes that it is running in 32-bit mode, by addressing the bitmask as a series of int values, instead of longs. This is broken as can easily be reproduced by running numademo on a bit-endian 64-bit system.

Changing the addressing to use 'long' values fixes the problem.