restore: Add restorer test

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

Makefile

@@ -67,6 +67,7 @@ OBJS		+= util.o
 OBJS		+= rbtree.o
 OBJS		+= elf.o
 OBJS		+= seize.o
+OBJS		+= restorer.o
 
 DEPS		:= $(patsubst %.o,%.d,$(OBJS))
 

cr-restore.c

@@ -26,6 +26,7 @@
 
 #include "image.h"
 #include "util.h"
+#include "restorer.h"
 
 #include "crtools.h"
 
@@ -1217,8 +1218,35 @@ static int restore_all_tasks(pid_t pid)
 	return restore_root_task(path, pstree_fd);
 }
 
+static void restorer_test(void)
+{
+	restorer_fcall_t restorer_fcall;
+	void *args_rip;
+	void *exec_mem;
+
+	exec_mem = mmap(0, RESTORER_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE | MAP_ANON, 0, 0);
+	if (exec_mem == MAP_FAILED) {
+		pr_err("Can't mmap exec\n");
+		return;
+	}
+
+	memcpy(exec_mem, &restorer, RESTORER_SIZE);
+	restorer_fcall = exec_mem;
+	restorer_fcall(RESTORER_CMD__GET_ARG_OFFSET);
+
+	args_rip = (void *)restorer_fcall(RESTORER_CMD__GET_ARG_OFFSET);
+
+	strcpy(args_rip, "Hello from restorer!\n");
+	restorer_fcall(RESTORER_CMD__PR_ARG_STRING);
+
+	exit(0);
+
+}
+
 int cr_restore_tasks(pid_t pid, struct cr_options *opts)
 {
+	restorer_test();
+
 	if (opts->leader_only)
 		return restore_one_task(pid);
 	return restore_all_tasks(pid);

include/restorer.h

+#ifndef CR_RESTORER_H__
+#define CR_RESTORER_H__
+
+#include "image.h"
+
+#define RESTORER_ARGS_SIZE	512
+#define RESTORER_SIZE		4096
+
+long restorer(long cmd);
+
+typedef long (*restorer_fcall_t) (long cmd);
+
+enum {
+	RESTORER_CMD__NONE,
+	RESTORER_CMD__GET_ARG_OFFSET,
+	RESTORER_CMD__PR_ARG_STRING,
+	RESTORER_CMD__MAX,
+};
+
+#endif /* CR_RESTORER_H__ */

restorer.c

+#include <stdio.h>
+#include <stdlib.h>
+
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include "compiler.h"
+#include "types.h"
+#include "syscall.h"
+#include "util.h"
+#include "image.h"
+
+#include "restorer.h"
+
+long restorer(long cmd)
+{
+	long ret;
+
+	asm volatile(
+		"jmp 1f						\n\t"
+		"restore_args__:				\n\t"
+		".skip "__stringify(RESTORER_ARGS_SIZE)",0	\n\t"
+		"1:						\n\t"
+		:
+		:
+		: "memory");
+
+	switch (cmd) {
+	case RESTORER_CMD__PR_ARG_STRING:
+	{
+		char *str = NULL;
+		int size = 0;
+
+		asm volatile(
+			"leaq restore_args__(%%rip), %%rax	\n\t"
+			"movq %%rax, %0				\n\t"
+			: "=m"(str)
+			:
+			: "memory");
+
+		while (str[size])
+			size++;
+		sys_write(1, str, size);
+	}
+		break;
+
+	case RESTORER_CMD__GET_ARG_OFFSET:
+		asm volatile(
+			"leaq restore_args__(%%rip), %%rax	\n\t"
+			"movq %%rax, %0				\n\t"
+			: "=m"(ret)
+			:
+			: "memory");
+		break;
+
+	}
+
+	asm volatile(".align "__stringify(RESTORER_SIZE));
+
+	return ret;
+}