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29 //
30 // Helper program for the linux_dumper class, which creates a bunch of
31 // threads. The first word of each thread's stack is set to the thread
32 // id.
33 
34 #include <pthread.h>
35 #include <stdint.h>
36 #include <stdio.h>
37 #include <stdlib.h>
38 #include <sys/syscall.h>
39 #include <unistd.h>
40 
41 #include "common/scoped_ptr.h"
42 #include "third_party/lss/linux_syscall_support.h"
43 
44 #if defined(__ARM_EABI__)
45 #define TID_PTR_REGISTER "r3"
46 #elif defined(__aarch64__)
47 #define TID_PTR_REGISTER "x3"
48 #elif defined(__i386)
49 #define TID_PTR_REGISTER "ecx"
50 #elif defined(__x86_64)
51 #define TID_PTR_REGISTER "rcx"
52 #elif defined(__mips__)
53 #define TID_PTR_REGISTER "$1"
54 #else
55 #error This test has not been ported to this platform.
56 #endif
57 
thread_function(void * data)58 void *thread_function(void *data) {
59   int pipefd = *static_cast<int *>(data);
60   volatile pid_t thread_id = syscall(__NR_gettid);
61   // Signal parent that a thread has started.
62   uint8_t byte = 1;
63   if (write(pipefd, &byte, sizeof(byte)) != sizeof(byte)) {
64     perror("ERROR: parent notification failed");
65     return NULL;
66   }
67   register volatile pid_t *thread_id_ptr asm(TID_PTR_REGISTER) = &thread_id;
68   while (true)
69     asm volatile ("" : : "r" (thread_id_ptr));
70   return NULL;
71 }
72 
main(int argc,char * argv[])73 int main(int argc, char *argv[]) {
74   if (argc < 3) {
75     fprintf(stderr,
76             "usage: linux_dumper_unittest_helper <pipe fd> <# of threads>\n");
77     return 1;
78   }
79   int pipefd = atoi(argv[1]);
80   int num_threads = atoi(argv[2]);
81   if (num_threads < 1) {
82     fprintf(stderr, "ERROR: number of threads is 0");
83     return 1;
84   }
85   google_breakpad::scoped_array<pthread_t> threads(new pthread_t[num_threads]);
86   pthread_attr_t thread_attributes;
87   pthread_attr_init(&thread_attributes);
88   pthread_attr_setdetachstate(&thread_attributes, PTHREAD_CREATE_DETACHED);
89   for (int i = 1; i < num_threads; i++) {
90     pthread_create(&threads[i], &thread_attributes, &thread_function, &pipefd);
91   }
92   thread_function(&pipefd);
93   return 0;
94 }
95