Attachment 219458 Details for Bug 250954 – Minimal demonstration program

Minimal demonstration program

thread-dbreg-test-pt.c (text/plain), 2.58 KB, created by Michał Górny on 2020-11-08 15:02:21 UTC

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Creator: Michał Górny

Created: 2020-11-08 15:02:21 UTC

Size: 2.58 KB

patch

obsolete

>#include <assert.h>
>#include <pthread.h>
>#include <signal.h>
>#include <stdio.h>
>#include <unistd.h>
>#include <sys/ptrace.h>
>#include <sys/wait.h>
>#include <machine/reg.h>
>
>volatile int g_val;
>volatile int g_val2;
>
>void* thread_func(void* foo) {
>	return NULL;
>}
>
>int main() {
>	int ret;
>	int pid = fork();
>	assert(pid != -1);
>	if (pid == 0) {
>		int i;
>		pthread_t t2;
>
>		ret = ptrace(PT_TRACE_ME, 0, NULL, 0);
>		assert(ret != -1);
>		// 2. wait for parent to set dbregs
>		raise(SIGSTOP);
>
>		// 4. start new thread and stop immediately afterwards
>		ret = pthread_create(&t2, NULL, thread_func, NULL);
>		assert(ret == 0);
>		raise(SIGSTOP);
>		printf("thread started\n");
>
>		ret = pthread_join(t2, NULL);
>		assert(ret == 0);
>		printf("thread joined\n");
>		_exit(0);
>	}
>
>	// 1. wait for the child to start
>	pid_t waited = waitpid(pid, &ret, 0);
>	printf("wait: pid=%d, ret=%d\n", pid, ret);
>	assert(waited == pid);
>	assert(WSTOPSIG(ret) == SIGSTOP);
>
>	// 3. set event mask & dbregs
>	int ev = PTRACE_LWP;
>	ret = ptrace(PT_SET_EVENT_MASK, pid, &ev, sizeof(ev));
>	assert(ret != -1);
>
>	struct dbreg db;
>	ret = ptrace(PT_GETDBREGS, pid, &db, 0);
>	assert(ret != -1);
>
>	db.dr[0] = &g_val;
>	db.dr[7] = 0x303;
>	ret = ptrace(PT_SETDBREGS, pid, &db, 0);
>	assert(ret != -1);
>
>	ret = ptrace(PT_CONTINUE, pid, (void*)1, 0);
>	assert(ret != -1);
>
>	// 5. we should get SIGSTOP first, change dbregs
>	waited = waitpid(pid, &ret, 0);
>	printf("wait: pid=%d, ret=%d\n", pid, ret);
>	assert(waited == pid);
>	assert(WSTOPSIG(ret) == SIGSTOP);
>
>	ret = ptrace(PT_GETDBREGS, pid, &db, 0);
>	assert(ret != -1);
>
>	db.dr[0] = &g_val2;
>	db.dr[7] = 0x303;
>	ret = ptrace(PT_SETDBREGS, pid, &db, 0);
>	assert(ret != -1);
>
>	ret = ptrace(PT_CONTINUE, pid, (void*)1, 0);
>	assert(ret != -1);
>
>	// 6. now we should get new thread event
>	waited = waitpid(pid, &ret, 0);
>	printf("wait: pid=%d, ret=%d\n", pid, ret);
>	assert(waited == pid);
>	assert(WSTOPSIG(ret) == SIGTRAP);
>
>	struct ptrace_lwpinfo info;
>	ret = ptrace(PT_LWPINFO, pid, &info, sizeof(info));
>	assert(ret != -1);
>	printf("tid = %d\n", info.pl_lwpid);
>
>	ret = ptrace(PT_GETDBREGS, info.pl_lwpid, &db, 0);
>	assert(ret != -1);
>	printf("dr0=%p, g_val=%p, g_val2=%p\n", db.dr[0], &g_val, &g_val2);
>
>	ret = ptrace(PT_CONTINUE, pid, (void*)1, 0);
>	assert(ret != -1);
>
>	// thread exited
>	waited = waitpid(pid, &ret, 0);
>	printf("wait: pid=%d, ret=%d\n", pid, ret);
>	assert(waited == pid);
>	assert(WSTOPSIG(ret) == SIGTRAP);
>
>	ret = ptrace(PT_CONTINUE, pid, (void*)1, 0);
>	assert(ret != -1);
>
>	waited = waitpid(pid, &ret, 0);
>	printf("wait: pid=%d, ret=%d\n", pid, ret);
>	assert(waited == pid);
>	assert(WIFEXITED(ret));
>
>	return 0;
>}

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Attachments on bug 250954: 219458 | 219480 | 219487