dump: Obtain task brk via misc dump command

Right now we do syscall_seized for this, but we have the misc dumping command
and the core is (after patch #3) dump after parasite, so we can get brk from
the misc dump, thus avoiding one more switch to parasite.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>

cr-dump.c

@@ -665,7 +665,7 @@ static int dump_task_core(struct core_entry *core, struct cr_fdset *fdset)
 }
 
 static int dump_task_core_all(pid_t pid, int pid_dir, struct proc_pid_stat *stat,
-		struct cr_fdset *cr_fdset)
+		struct parasite_dump_misc *misc, struct cr_fdset *cr_fdset)
 {
 	struct core_entry *core		= xzalloc(sizeof(*core));
 	int ret				= -1;
@@ -704,6 +704,8 @@ static int dump_task_core_all(pid_t pid, int pid_dir, struct proc_pid_stat *stat
 	core->tc.mm_env_start = stat->env_start;
 	core->tc.mm_env_end = stat->env_end;
 
+	core->tc.mm_brk = misc->brk;
+
 	pr_info("Obtainting sigmask ... ");
 	ret = get_task_sigmask(pid, pid_dir, &core->tc.blk_sigset);
 	if (ret)
@@ -716,13 +718,6 @@ static int dump_task_core_all(pid_t pid, int pid_dir, struct proc_pid_stat *stat
 		goto err_free;
 	pr_info("OK\n");
 
-	pr_info("Obtainting task brk ... ");
-	brk = brk_seized(pid, 0);
-	if ((long)brk < 0)
-		goto err_free;
-	core->tc.mm_brk = brk;
-	pr_info("OK\n");
-
 	core->tc.task_state = TASK_ALIVE;
 	core->tc.exit_code = 0;
 
@@ -1254,7 +1249,7 @@ static int dump_one_task(struct pstree_item *item, struct cr_fdset *cr_fdset)
 		goto err;
 	}
 
-	ret = dump_task_core_all(pid, pid_dir, &pps_buf, cr_fdset);
+	ret = dump_task_core_all(pid, pid_dir, &pps_buf, &misc, cr_fdset);
 	if (ret) {
 		pr_err("Dump core (pid: %d) failed with %d\n", pid, ret);
 		goto err;

include/parasite-syscall.h

@@ -28,7 +28,6 @@ extern void *mmap_seized(pid_t pid, user_regs_struct_t *regs,
 
 extern int munmap_seized(pid_t pid, user_regs_struct_t *regs,
 			 void *addr, size_t length);
-extern unsigned long brk_seized(pid_t pid, unsigned long addr);
 
 extern int syscall_seized(pid_t pid,
 			  user_regs_struct_t *where,

include/parasite.h

@@ -89,6 +89,7 @@ struct parasite_dump_pages_args {
 struct parasite_dump_misc {
 	parasite_status_t	status;
 	unsigned int		secbits;
+	unsigned long		brk;
 };
 
 /*

include/syscall.h

@@ -258,6 +258,11 @@ static always_inline long sys_prctl(int code, unsigned long arg2, unsigned long
 	return syscall5(__NR_prctl, code, arg2, arg3, arg4, arg5);
 }
 
+static always_inline long sys_brk(unsigned long arg)
+{
+	return syscall1(__NR_brk, arg);
+}
+
 static always_inline long sys_clone(unsigned long flags, void *child_stack,
 				    void *parent_tid, void *child_tid)
 {

parasite-syscall.c

@@ -92,31 +92,6 @@ int munmap_seized(pid_t pid, user_regs_struct_t *regs,
 	return ret;
 }
 
-unsigned long brk_seized(pid_t pid, unsigned long addr)
-{
-	user_regs_struct_t params, regs_orig;
-	unsigned long ret = -1UL;
-
-	jerr(ptrace(PTRACE_GETREGS, pid, NULL, &regs_orig), err);
-	params = regs_orig;
-
-	params.ax	= (unsigned long)__NR_brk;	/* brk		*/
-	params.di	= (unsigned long)addr;		/* @addr	*/
-
-	ret = syscall_seized(pid, &regs_orig, &params, &params);
-	if (!ret)
-		ret = (unsigned long)params.ax;
-	else
-		ret = -1UL;
-
-	if (ptrace(PTRACE_SETREGS, pid, NULL, &regs_orig)) {
-		pr_panic("Can't restore registers (pid: %d)\n", pid);
-		ret = -1UL;
-	}
-err:
-	return ret;
-}
-
 int syscall_seized(pid_t pid,
 		   user_regs_struct_t *where,
 		   user_regs_struct_t *params,

parasite.c

@@ -363,6 +363,7 @@ static int dump_misc(struct parasite_dump_misc *args)
 	parasite_status_t *st = &args->status;
 
 	args->secbits = sys_prctl(PR_GET_SECUREBITS, 0, 0, 0, 0);
+	args->brk = sys_brk(0);
 
 	SET_PARASITE_STATUS(st, 0, 0);
 	return 0;