CPU: Handle breakpoint trap

Also, start working on the debugger app.

1 files changed, 123 insertions, 0 deletions

diff --git a/Applications/Debugger/main.cpp b/Applications/Debugger/main.cpp
new file mode 100644
index 0000000000..fd76270957
--- /dev/null
+++ b/Applications/Debugger/main.cpp
@@ -0,0 +1,123 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/Assertions.h>
+#include <LibC/sys/arch/i386/regs.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ptrace.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+static int usage()
+{
+    printf("usage: sdb [command...]\n");
+    return 1;
+}
+
+static int g_pid = -1;
+
+static void handle_sigint(int)
+{
+    if (g_pid == -1)
+        return;
+
+    if (ptrace(PT_DETACH, g_pid, 0, 0) == -1) {
+        perror("detach");
+    }
+}
+
+void run_child_and_attach(char** argv)
+{
+    int pid = fork();
+
+    if (!pid) {
+        if (ptrace(PT_TRACE_ME, 0, 0, 0) == -1) {
+            perror("traceme");
+            return exit(1);
+        }
+
+        int rc = execvp(argv[1], &argv[1]);
+        if (rc < 0) {
+            perror("execvp");
+            exit(1);
+        }
+        ASSERT_NOT_REACHED();
+    }
+
+    if (waitpid(pid, nullptr, WSTOPPED) != pid) {
+        perror("waitpid");
+        exit(1);
+    }
+    g_pid = pid;
+}
+
+int main(int argc, char** argv)
+{
+    if (argc == 1)
+        return usage();
+
+    run_child_and_attach(argv);
+
+    struct sigaction sa;
+    memset(&sa, 0, sizeof(struct sigaction));
+    sa.sa_handler = handle_sigint;
+    sigaction(SIGINT, &sa, nullptr);
+
+    if (ptrace(PT_ATTACH, g_pid, 0, 0) == -1) {
+        perror("attach");
+        return 1;
+    }
+    if (waitpid(g_pid, nullptr, WSTOPPED) != g_pid) {
+        perror("waitpid");
+        return 1;
+    }
+
+    if (ptrace(PT_CONTINUE, g_pid, 0, 0) == -1) {
+        perror("continue");
+    }
+
+    // wait for breakpoint
+    if (waitpid(g_pid, nullptr, WSTOPPED) != g_pid) {
+        perror("waitpid");
+        return 1;
+    }
+
+    printf("hit breakpoint\n");
+
+    sleep(1);
+
+    if (ptrace(PT_CONTINUE, g_pid, 0, 0) == -1) {
+        perror("continue");
+    }
+
+    if (waitpid(g_pid, nullptr, WSTOPPED) != g_pid) {
+        perror("waitpid");
+        return 1;
+    }
+}