memcheck/tests/test-plo.c

   1 #include "tests/malloc.h"
   2 #include "pub_core_basics.h"
   3 #include <stdio.h>
   4 #include <assert.h>
   5
   6 __attribute__((noinline))
   7 static int my_ffsll ( ULong x )
   8 {
   9    int i;
  10    for (i = 0; i < 64; i++) {
  11       if ((x & 1ULL) == 1ULL)
  12          break;
  13       x >>= 1;
  14    }
  15    return i+1;
  16 }
  17
  18 /* Find length of string, assuming it is aligned and shorter than 8
  19    characters.  Little-endian only. */
  20 __attribute__((noinline))
  21 static int aligned_strlen(char *s)
  22 {
  23     /* This is for 64-bit platforms */
  24     assert(sizeof(ULong) == 8);
  25     /* ..and only works for aligned input */
  26     assert(((unsigned long)s & 0x7) == 0);
  27
  28     /* read 8 bytes */
  29     ULong val = *(ULong*)s;
  30     /* Subtract one from each byte */
  31     ULong val2 = val - 0x0101010101010101ULL;
  32     /* Find lowest byte whose high bit changed */
  33     val2 ^= val;
  34     val2 &= 0x8080808080808080ULL;
  35
  36     return (my_ffsll(val2) / 8) - 1;
  37 }
  38
  39 __attribute__((noinline)) void foo ( int x )
  40 {
  41    __asm__ __volatile__("":::"memory");
  42 }
  43
  44 int
  45 main(int argc, char *argv[])
  46 {
  47     char *buf = memalign16(5);
  48     buf[0] = 'a';
  49     buf[1] = 'b';
  50     buf[2] = 'c';
  51     buf[3] = 'd';
  52     buf[4] = '\0';
  53
  54     /* --partial-loads-ok=no:  expect addr error (here) */
  55     /* --partial-loads-ok=yes: expect no error */
  56     if (aligned_strlen(buf) == 4)
  57         foo(44);
  58
  59     /* --partial-loads-ok=no:  expect addr error (here) */
  60     /* --partial-loads-ok=yes: expect value error (in my_ffsll) */
  61     buf[4] = 'x';
  62     if (aligned_strlen(buf) == 0)
  63         foo(37);
  64
  65     free(buf);
  66
  67     /* Also, we need to check that a completely out-of-range,
  68        word-sized load gives an addressing error regardless of the
  69        start of --partial-loads-ok=.  *And* that the resulting
  70        value is completely defined. */
  71     RegWord* words = malloc(3 * sizeof(RegWord));
  72     free(words);
  73
  74     /* Should ALWAYS give an addr error. */
  75     RegWord  w     = words[1];
  76
  77     /* Should NEVER give an error (you might expect a value one, but no.) */
  78     if (w == 0x31415927) {
  79        fprintf(stderr,
  80                "Elvis is alive and well and living in Milton Keynes.\n");
  81     }
  82
  83     return 0;
  84 }