From 3e2980613c38f8e9babbb86bf35969ad3b0999ef Mon Sep 17 00:00:00 2001
From: Stefani Seibold <stefani@seibold.net>
Date: Mon, 23 May 2016 10:27:47 +0200
Subject: [PATCH] more accurate single step, prelink fixes, cleanup

---
 backend.h                 |  2 +-
 breakpoint.c              | 12 ++++++++++--
 breakpoint.h              |  2 ++
 library.c                 |  2 +-
 library.h                 |  3 ---
 main.c                    |  8 ++++----
 sysdeps/linux-gnu/os.c    |  9 ++++-----
 sysdeps/linux-gnu/proc.c  |  2 +-
 sysdeps/linux-gnu/trace.c | 22 +++++++++++-----------
 task.c                    |  4 ++--
 task.h                    |  2 +-
 11 files changed, 37 insertions(+), 31 deletions(-)

diff --git a/backend.h b/backend.h
index 71e4b7c..905d122 100644
--- a/backend.h
+++ b/backend.h
@@ -177,7 +177,7 @@ void wait_event_wakeup(void);
 int is_64bit(struct mt_elf *mte);
 
 /* change user id of a running process */
-void change_uid(const char *command);
+void change_uid(void);
 
 #endif
 
diff --git a/breakpoint.c b/breakpoint.c
index 43588e9..a9513dc 100644
--- a/breakpoint.c
+++ b/breakpoint.c
@@ -73,6 +73,9 @@ static void enable_sw_breakpoint(struct task *task, struct breakpoint *bp)
 	debug(DEBUG_PROCESS, "pid=%d, addr=%#lx", task->pid, bp->addr);
 
 	copy_from_to_proc(task, bp->addr, break_insn, bp->orig_value, BREAKPOINT_LENGTH);
+
+	bp->break_insn = !memcmp(break_insn, bp->orig_value, BREAKPOINT_LENGTH);
+	bp->was_hw = 0;
 }
 
 static void disable_sw_breakpoint(struct task *task, const struct breakpoint *bp)
@@ -230,6 +233,7 @@ void reorder_hw_bp(struct task *task)
 
 		bp->hw_bp_slot = i;
 		bp->hw = 1;
+		bp->was_hw = 1;
 
 		each_task(leader, enable_hw_bp_cb, bp);
 
@@ -260,6 +264,7 @@ static int insert_hw_bp_slot(struct task *task, struct breakpoint *bp)
 	bp->enabled = 1;
 	bp->hw_bp_slot = i;
 	bp->hw = 1;
+	bp->was_hw = 1;
 
 	each_task(leader, enable_hw_bp_cb, bp);
 
@@ -357,6 +362,7 @@ struct breakpoint *breakpoint_new_ext(struct task *task, arch_addr_t addr, struc
 	bp->enabled = 0;
 	bp->locked = 0;
 	bp->deleted = 0;
+	bp->break_insn = 0;
 	bp->ext = ext;
 	bp->refcnt = 1;
 	bp->count = 0;
@@ -383,6 +389,7 @@ struct breakpoint *breakpoint_new_ext(struct task *task, arch_addr_t addr, struc
 	case BP_SW:
 		memset(bp->orig_value, 0, sizeof(bp->orig_value));
 		bp->hw = 0;
+		bp->was_hw = 0;
 	}
 
 	if (dict_add(leader->breakpoints, (unsigned long)addr, bp) < 0) {
@@ -505,12 +512,13 @@ void breakpoint_delete(struct task *task, struct breakpoint *bp)
 
 	if (unlikely(options.verbose > 1 && bp->libsym)) {
 		fprintf(stderr,
-			"delete %s breakpoint %s:%s [%#lx] count=%u\n",
+			"delete %s breakpoint %s:%s [%#lx] count=%u was_hw=%u\n",
 				bp->type == BP_SW ? "sw" : "hw",
 				bp->libsym->libref->filename,
 				bp->libsym->func->demangled_name,
 				bp->addr,
-				bp->count);
+				bp->count,
+				bp->was_hw);
 	}
 
 	bp->deleted = 1;
diff --git a/breakpoint.h b/breakpoint.h
index 6a2bd0a..b391c4a 100644
--- a/breakpoint.h
+++ b/breakpoint.h
@@ -51,6 +51,8 @@ struct breakpoint {
 	unsigned int locked:1;
 	unsigned int deleted:1;
 	unsigned int hw:1;
+	unsigned int was_hw:1;
+	unsigned int break_insn:1;
 	union {
 		unsigned char orig_value[BREAKPOINT_LENGTH];
 #if HW_BREAKPOINTS > 0
diff --git a/library.c b/library.c
index 0c34d34..2e20aef 100644
--- a/library.c
+++ b/library.c
@@ -113,7 +113,7 @@ struct library_symbol *library_symbol_new(struct libref *libref, arch_addr_t add
 	return libsym;
 }
 
-void library_delete(struct task *task, struct library *lib)
+static void library_delete(struct task *task, struct library *lib)
 {
 	if (lib == NULL)
 		return;
diff --git a/library.h b/library.h
index 3d2e667..d3b8e50 100644
--- a/library.h
+++ b/library.h
@@ -101,9 +101,6 @@ struct library {
 /* create a new symbol */
 struct library_symbol *library_symbol_new(struct libref *libref, arch_addr_t addr, const struct function *func);
 
-/* Delete library. Symbols are destroyed and freed. */
-void library_delete(struct task *leader, struct library *lib);
-
 /* Add a library to the list of the thread leader libraries.  */
 struct library *library_add(struct task *leader, struct libref *libref);
 
diff --git a/main.c b/main.c
index 96c8bd3..c940c13 100644
--- a/main.c
+++ b/main.c
@@ -104,12 +104,12 @@ static void mtrace_exit(void)
 	each_pid(remove_task);
 }
 
-static void mtrace_init(char **cmd)
+static void mtrace_init(char **cmd_args)
 {
 	struct opt_p_t *opt_p_tmp;
 
 	if (options.command) {
-		struct task *task = task_create(options.command, cmd);
+		struct task *task = task_create(cmd_args);
 			
 		if (!task)
 			exit(EXIT_FAILURE);
@@ -138,7 +138,7 @@ static void mtrace_main(void)
 
 int main(int argc, char *argv[])
 {
-	char **cmd = process_options(argc, argv);
+	char **cmd_args = process_options(argc, argv);
 
 	init_pid_hash();
 
@@ -186,7 +186,7 @@ int main(int argc, char *argv[])
 	if (os_init())
 		exit(EXIT_FAILURE);
 
-	mtrace_init(cmd);
+	mtrace_init(cmd_args);
 	mtrace_main();
 	mtrace_exit();
 
diff --git a/sysdeps/linux-gnu/os.c b/sysdeps/linux-gnu/os.c
index 5d68bb7..3deaed5 100644
--- a/sysdeps/linux-gnu/os.c
+++ b/sysdeps/linux-gnu/os.c
@@ -315,7 +315,7 @@ finish:
 	return blocks;
 }
 
-void change_uid(const char *command)
+void change_uid(void)
 {
 	uid_t run_uid, run_euid;
 	gid_t run_gid, run_egid;
@@ -348,12 +348,11 @@ void change_uid(const char *command)
 		run_egid = run_gid;
 
 		if (!stat(options.command, &statbuf)) {
-			if (statbuf.st_mode & S_ISUID) {
+			if (statbuf.st_mode & S_ISUID)
 				run_euid = statbuf.st_uid;
-			}
-			if (statbuf.st_mode & S_ISGID) {
+
+			if (statbuf.st_mode & S_ISGID)
 				run_egid = statbuf.st_gid;
-			}
 		}
 		if (setregid(run_gid, run_egid) < 0) {
 			perror("mtrace-ng: setregid");
diff --git a/sysdeps/linux-gnu/proc.c b/sysdeps/linux-gnu/proc.c
index 8c09312..6578a67 100644
--- a/sysdeps/linux-gnu/proc.c
+++ b/sysdeps/linux-gnu/proc.c
@@ -462,7 +462,7 @@ static void linkmap_del(struct task *task, struct lt_r_debug_64 *dbg)
 
 		addr = ARCH_ADDR_T(rlm.l_next);
 
-		lib = library_find_with_key(&tmp_list, ARCH_ADDR_T(rlm.l_addr));
+		lib = library_find_with_key(&tmp_list, ARCH_ADDR_T(rlm.l_ld));
 		if (lib)
 			list_move_tail(&lib->list, &task->libraries_list);
 	}
diff --git a/sysdeps/linux-gnu/trace.c b/sysdeps/linux-gnu/trace.c
index 97eb2e2..4947dcb 100644
--- a/sysdeps/linux-gnu/trace.c
+++ b/sysdeps/linux-gnu/trace.c
@@ -466,7 +466,6 @@ int handle_singlestep(struct task *task, int (*singlestep)(struct task *task), s
 	int status;
 	int stop_signal;
 	unsigned long ip;
-	int ret;
 
 	for(;;) {
 		if (unlikely(singlestep(task) == -1))
@@ -489,26 +488,27 @@ int handle_singlestep(struct task *task, int (*singlestep)(struct task *task), s
 		}
 
 		if (ip != bp->addr) {
-			ret = 0;
-
-			if (likely(stop_signal == SIGTRAP))
-				return ret;
+			if (likely(stop_signal == SIGTRAP)) {
+				if (bp->break_insn) {
+					queue_event(task);
+					return 1;
+				}
+				return 0;
+			}
 		}
-		else
-			ret = 1;
 
 		if (likely(!stop_signal)) {
 			queue_event(task);
-			return ret;
+			return 1;
 		}
 
 		if (fix_signal(task, stop_signal) > 0) {
 			queue_event(task);
-			return ret;
+			return 1;
 		}
 
-		if (!ret)
-			return ret;
+		if (ip != bp->addr)
+			return 0;
 	}
 }
 
diff --git a/task.c b/task.c
index 3a9377a..642bda6 100644
--- a/task.c
+++ b/task.c
@@ -305,7 +305,7 @@ fail:
 	return -1;
 }
 
-struct task *task_create(const char *command, char **argv)
+struct task *task_create(char **argv)
 {
 	struct task *task;
 	pid_t pid;
@@ -319,7 +319,7 @@ struct task *task_create(const char *command, char **argv)
 	}
 
 	if (!pid) { /* child */
-		change_uid(options.command);
+		change_uid();
 		trace_me();
 		execvp(options.command, argv);
 		fprintf(stderr, "Can't execute `%s': %s\n", options.command, strerror(errno));
diff --git a/task.h b/task.h
index 3b86ce4..cf8ece4 100644
--- a/task.h
+++ b/task.h
@@ -119,7 +119,7 @@ int process_exec(struct task *task);
 
 struct task *task_new(pid_t pid);
 
-struct task *task_create(const char *command, char **argv);
+struct task *task_create(char **argv);
 
 void open_pid(pid_t pid);