/* This is an example of a program which does atomic memory operations
between two processes which share a page. Valgrind 3.4.1 and
earlier produce incorrect answers because it does not preserve
atomicity of the relevant instructions in the generated code; but
the post-DCAS-merge versions of Valgrind do behave correctly. */
/* On ARM, this can be compiled into either ARM or Thumb code, so as
to test both A and T encodings of LDREX/STREX et al. Also on ARM,
it tests doubleword atomics (LDREXD, STREXD) which I don't think it
does on any other platform. */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <unistd.h>
#include <sys/wait.h>
#include "tests/sys_mman.h"
#define NNN 3456987
#define IS_8_ALIGNED(_ptr) (0 == (((unsigned long)(_ptr)) & 7))
__attribute__((noinline)) void atomic_add_8bit ( char* p, int n )
{
#if defined(VGA_x86)
unsigned long block[2];
block[0] = (unsigned long)p;
block[1] = n;
__asm__ __volatile__(
"movl 0(%%esi),%%eax" "\n\t"
"movl 4(%%esi),%%ebx" "\n\t"
"lock; addb %%bl,(%%eax)" "\n"
: : "S"(&block[0])/* S means "esi only" */ : "memory","cc","eax","ebx"
);
#elif defined(VGA_amd64)
unsigned long block[2];
block[0] = (unsigned long)p;
block[1] = n;
__asm__ __volatile__(
"movq 0(%%rsi),%%rax" "\n\t"
"movq 8(%%rsi),%%rbx" "\n\t"
"lock; addb %%bl,(%%rax)" "\n"
: : "S"(&block[0])/* S means "rsi only" */ : "memory","cc","rax","rbx"
);
#elif defined(VGA_ppc32)
/* Nasty hack. Does correctly atomically do *p += n, but only if p
is 4-aligned -- guaranteed by caller. */
unsigned long success;
do {
__asm__ __volatile__(
"lwarx 15,0,%1" "\n\t"
"add 15,15,%2" "\n\t"
"stwcx. 15,0,%1" "\n\t"
"mfcr %0" "\n\t"
"srwi %0,%0,29" "\n\t"
"andi. %0,%0,1" "\n"
: /*out*/"=b"(success)
: /*in*/ "b"(p), "b"(((unsigned long)n) << 24)
: /*trash*/ "memory", "cc", "r15"
);
} while (success != 1);
#elif defined(VGA_ppc64)
/* Nasty hack. Does correctly atomically do *p += n, but only if p
is 8-aligned -- guaranteed by caller. */
unsigned long success;
do {
__asm__ __volatile__(
"ldarx 15,0,%1" "\n\t"
"add 15,15,%2" "\n\t"
"stdcx. 15,0,%1" "\n\t"
"mfcr %0" "\n\t"
"srwi %0,%0,29" "\n\t"
"andi. %0,%0,1" "\n"
: /*out*/"=b"(success)
: /*in*/ "b"(p), "b"(((unsigned long)n) << 56)
: /*trash*/ "memory", "cc", "r15"
);
} while (success != 1);
#elif defined(VGA_arm)
unsigned int block[3]
= { (unsigned int)p, (unsigned int)n, 0xFFFFFFFF };
do {
__asm__ __volatile__(
"mov r5, %0" "\n\t"
"ldr r9, [r5, #0]" "\n\t" // p
"ldr r10, [r5, #4]" "\n\t" // n
"ldrexb r8, [r9]" "\n\t"
"add r8, r8, r10" "\n\t"
"strexb r4, r8, [r9]" "\n\t"
"str r4, [r5, #8]" "\n\t"
: /*out*/
: /*in*/ "r"(&block[0])
: /*trash*/ "memory", "cc", "r5", "r8", "r9", "r10", "r4"
);
} while (block[2] != 0);
#elif defined(VGA_s390x)
int dummy;
__asm__ __volatile__(
" l 0,%0\n\t"
"0: st 0,%1\n\t"
" icm 1,1,%1\n\t"
" ar 1,%2\n\t"
" stcm 1,1,%1\n\t"
" l 1,%1\n\t"
" cs 0,1,%0\n\t"
" jl 0b\n\t"
: "+m" (*p), "+m" (dummy)
: "d" (n)
: "cc", "memory", "0", "1");
#else
# error "Unsupported arch"
#endif
}
__attribute__((noinline)) void atomic_add_16bit ( short* p, int n )
{
#if defined(VGA_x86)
unsigned long block[2];
block[0] = (unsigned long)p;
block[1] = n;
__asm__ __volatile__(
"movl 0(%%esi),%%eax" "\n\t"
"movl 4(%%esi),%%ebx" "\n\t"
"lock; addw %%bx,(%%eax)" "\n"
: : "S"(&block[0])/* S means "esi only" */ : "memory","cc","eax","ebx"
);
#elif defined(VGA_amd64)
unsigned long block[2];
block[0] = (unsigned long)p;
block[1] = n;
__asm__ __volatile__(
"movq 0(%%rsi),%%rax" "\n\t"
"movq 8(%%rsi),%%rbx" "\n\t"
"lock; addw %%bx,(%%rax)" "\n"
: : "S"(&block[0])/* S means "rsi only" */ : "memory","cc","rax","rbx"
);
#elif defined(VGA_ppc32)
/* Nasty hack. Does correctly atomically do *p += n, but only if p
is 8-aligned -- guaranteed by caller. */
unsigned long success;
do {
__asm__ __volatile__(
"lwarx 15,0,%1" "\n\t"
"add 15,15,%2" "\n\t"
"stwcx. 15,0,%1" "\n\t"
"mfcr %0" "\n\t"
"srwi %0,%0,29" "\n\t"
"andi. %0,%0,1" "\n"
: /*out*/"=b"(success)
: /*in*/ "b"(p), "b"(((unsigned long)n) << 16)
: /*trash*/ "memory", "cc", "r15"
);
} while (success != 1);
#elif defined(VGA_ppc64)
/* Nasty hack. Does correctly atomically do *p += n, but only if p
is 8-aligned -- guaranteed by caller. */
unsigned long success;
do {
__asm__ __volatile__(
"ldarx 15,0,%1" "\n\t"
"add 15,15,%2" "\n\t"
"stdcx. 15,0,%1" "\n\t"
"mfcr %0" "\n\t"
"srwi %0,%0,29" "\n\t"
"andi. %0,%0,1" "\n"
: /*out*/"=b"(success)
: /*in*/ "b"(p), "b"(((unsigned long)n) << 48)
: /*trash*/ "memory", "cc", "r15"
);
} while (success != 1);
#elif defined(VGA_arm)
unsigned int block[3]
= { (unsigned int)p, (unsigned int)n, 0xFFFFFFFF };
do {
__asm__ __volatile__(
"mov r5, %0" "\n\t"
"ldr r9, [r5, #0]" "\n\t" // p
"ldr r10, [r5, #4]" "\n\t" // n
"ldrexh r8, [r9]" "\n\t"
"add r8, r8, r10" "\n\t"
"strexh r4, r8, [r9]" "\n\t"
"str r4, [r5, #8]" "\n\t"
: /*out*/
: /*in*/ "r"(&block[0])
: /*trash*/ "memory", "cc", "r5", "r8", "r9", "r10", "r4"
);
} while (block[2] != 0);
#elif defined(VGA_s390x)
int dummy;
__asm__ __volatile__(
" l 0,%0\n\t"
"0: st 0,%1\n\t"
" icm 1,3,%1\n\t"
" ar 1,%2\n\t"
" stcm 1,3,%1\n\t"
" l 1,%1\n\t"
" cs 0,1,%0\n\t"
" jl 0b\n\t"
: "+m" (*p), "+m" (dummy)
: "d" (n)
: "cc", "memory", "0", "1");
#else
# error "Unsupported arch"
#endif
}
__attribute__((noinline)) void atomic_add_32bit ( int* p, int n )
{
#if defined(VGA_x86)
unsigned long block[2];
block[0] = (unsigned long)p;
block[1] = n;
__asm__ __volatile__(
"movl 0(%%esi),%%eax" "\n\t"
"movl 4(%%esi),%%ebx" "\n\t"
"lock; addl %%ebx,(%%eax)" "\n"
: : "S"(&block[0])/* S means "esi only" */ : "memory","cc","eax","ebx"
);
#elif defined(VGA_amd64)
unsigned long block[2];
block[0] = (unsigned long)p;
block[1] = n;
__asm__ __volatile__(
"movq 0(%%rsi),%%rax" "\n\t"
"movq 8(%%rsi),%%rbx" "\n\t"
"lock; addl %%ebx,(%%rax)" "\n"
: : "S"(&block[0])/* S means "rsi only" */ : "memory","cc","rax","rbx"
);
#elif defined(VGA_ppc32)
unsigned long success;
do {
__asm__ __volatile__(
"lwarx 15,0,%1" "\n\t"
"add 15,15,%2" "\n\t"
"stwcx. 15,0,%1" "\n\t"
"mfcr %0" "\n\t"
"srwi %0,%0,29" "\n\t"
"andi. %0,%0,1" "\n"
: /*out*/"=b"(success)
: /*in*/ "b"(p), "b"(n)
: /*trash*/ "memory", "cc", "r15"
);
} while (success != 1);
#elif defined(VGA_ppc64)
/* Nasty hack. Does correctly atomically do *p += n, but only if p
is 8-aligned -- guaranteed by caller. */
unsigned long success;
do {
__asm__ __volatile__(
"ldarx 15,0,%1" "\n\t"
"add 15,15,%2" "\n\t"
"stdcx. 15,0,%1" "\n\t"
"mfcr %0" "\n\t"
"srwi %0,%0,29" "\n\t"
"andi. %0,%0,1" "\n"
: /*out*/"=b"(success)
: /*in*/ "b"(p), "b"(((unsigned long)n) << 32)
: /*trash*/ "memory", "cc", "r15"
);
} while (success != 1);
#elif defined(VGA_arm)
unsigned int block[3]
= { (unsigned int)p, (unsigned int)n, 0xFFFFFFFF };
do {
__asm__ __volatile__(
"mov r5, %0" "\n\t"
"ldr r9, [r5, #0]" "\n\t" // p
"ldr r10, [r5, #4]" "\n\t" // n
"ldrex r8, [r9]" "\n\t"
"add r8, r8, r10" "\n\t"
"strex r4, r8, [r9]" "\n\t"
"str r4, [r5, #8]" "\n\t"
: /*out*/
: /*in*/ "r"(&block[0])
: /*trash*/ "memory", "cc", "r5", "r8", "r9", "r10", "r4"
);
} while (block[2] != 0);
#elif defined(VGA_s390x)
__asm__ __volatile__(
" l 0,%0\n\t"
"0: lr 1,0\n\t"
" ar 1,%1\n\t"
" cs 0,1,%0\n\t"
" jl 0b\n\t"
: "+m" (*p)
: "d" (n)
: "cc", "memory", "0", "1");
#else
# error "Unsupported arch"
#endif
}
__attribute__((noinline)) void atomic_add_64bit ( long long int* p, int n )
{
#if defined(VGA_x86) || defined(VGA_ppc32)
/* do nothing; is not supported */
#elif defined(VGA_amd64)
// this is a bit subtle. It relies on the fact that, on a 64-bit platform,
// sizeof(unsigned long long int) == sizeof(unsigned long) == sizeof(void*)
unsigned long long int block[2];
block[0] = (unsigned long long int)(unsigned long)p;
block[1] = n;
__asm__ __volatile__(
"movq 0(%%rsi),%%rax" "\n\t"
"movq 8(%%rsi),%%rbx" "\n\t"
"lock; addq %%rbx,(%%rax)" "\n"
: : "S"(&block[0])/* S means "rsi only" */ : "memory","cc","rax","rbx"
);
#elif defined(VGA_ppc64)
unsigned long success;
do {
__asm__ __volatile__(
"ldarx 15,0,%1" "\n\t"
"add 15,15,%2" "\n\t"
"stdcx. 15,0,%1" "\n\t"
"mfcr %0" "\n\t"
"srwi %0,%0,29" "\n\t"
"andi. %0,%0,1" "\n"
: /*out*/"=b"(success)
: /*in*/ "b"(p), "b"(n)
: /*trash*/ "memory", "cc", "r15"
);
} while (success != 1);
#elif defined(VGA_arm)
unsigned long long int block[3]
= { (unsigned long long int)(unsigned long)p,
(unsigned long long int)n,
0xFFFFFFFFFFFFFFFFULL };
do {
__asm__ __volatile__(
"mov r5, %0" "\n\t"
"ldr r8, [r5, #0]" "\n\t" // p
"ldrd r2, r3, [r5, #8]" "\n\t" // n
"ldrexd r0, r1, [r8]" "\n\t"
"adds r2, r2, r0" "\n\t"
"adc r3, r3, r1" "\n\t"
"strexd r1, r2, r3, [r8]" "\n\t"
"str r1, [r5, #16]" "\n\t"
: /*out*/
: /*in*/ "r"(&block[0])
: /*trash*/ "memory", "cc", "r5", "r0", "r1", "r8", "r2", "r3"
);
} while (block[2] != 0xFFFFFFFF00000000ULL);
#elif defined(VGA_s390x)
__asm__ __volatile__(
" lg 0,%0\n\t"
"0: lgr 1,0\n\t"
" agr 1,%1\n\t"
" csg 0,1,%0\n\t"
" jl 0b\n\t"
: "+m" (*p)
: "d" (n)
: "cc", "memory", "0", "1");
#else
# error "Unsupported arch"
#endif
}
int main ( int argc, char** argv )
{
int i, status;
char* page;
char* p8;
short* p16;
int* p32;
long long int* p64;
pid_t child, p2;
printf("parent, pre-fork\n");
page = mmap( 0, sysconf(_SC_PAGESIZE),
PROT_READ|PROT_WRITE,
MAP_ANONYMOUS|MAP_SHARED, -1, 0 );
if (page == MAP_FAILED) {
perror("mmap failed");
exit(1);
}
p8 = (char*)(page+0);
p16 = (short*)(page+256);
p32 = (int*)(page+512);
p64 = (long long int*)(page+768);
assert( IS_8_ALIGNED(p8) );
assert( IS_8_ALIGNED(p16) );
assert( IS_8_ALIGNED(p32) );
assert( IS_8_ALIGNED(p64) );
memset(page, 0, 1024);
*p8 = 0;
*p16 = 0;
*p32 = 0;
*p64 = 0;
child = fork();
if (child == -1) {
perror("fork() failed\n");
return 1;
}
if (child == 0) {
/* --- CHILD --- */
printf("child\n");
for (i = 0; i < NNN; i++) {
atomic_add_8bit(p8, 1);
atomic_add_16bit(p16, 1);
atomic_add_32bit(p32, 1);
atomic_add_64bit(p64, 98765 ); /* ensure we hit the upper 32 bits */
}
return 1;
/* NOTREACHED */
}
/* --- PARENT --- */
printf("parent\n");
for (i = 0; i < NNN; i++) {
atomic_add_8bit(p8, 1);
atomic_add_16bit(p16, 1);
atomic_add_32bit(p32, 1);
atomic_add_64bit(p64, 98765 ); /* ensure we hit the upper 32 bits */
}
p2 = waitpid(child, &status, 0);
assert(p2 == child);
/* assert that child finished normally */
assert(WIFEXITED(status));
printf("FINAL VALUES: 8 bit %d, 16 bit %d, 32 bit %d, 64 bit %lld\n",
(int)(*(signed char*)p8), (int)(*p16), *p32, *p64 );
if (-74 == (int)(*(signed char*)p8)
&& 32694 == (int)(*p16)
&& 6913974 == *p32
&& (0LL == *p64 || 682858642110LL == *p64)) {
printf("PASS\n");
} else {
printf("FAIL -- see source code for expected values\n");
}
printf("parent exits\n");
return 0;
}