rst: Make shmem restore to use rst-malloc

This actually fixes a bug -- memory for shmem info was
not allocated dynamically, thus we were limited in the
amount of shmems to be restored.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

cr-restore.c

@@ -143,9 +143,6 @@ static int root_prepare_shared(void)
 
 	pr_info("Preparing info about shared resources\n");
 
-	if (prepare_shmem_restore())
-		return -1;
-
 	if (prepare_shared_tty())
 		return -1;
 
@@ -2166,7 +2163,6 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core)
 
 	BUILD_BUG_ON(sizeof(struct task_restore_core_args) & 1);
 	BUILD_BUG_ON(sizeof(struct thread_restore_args) & 1);
-	BUILD_BUG_ON(SHMEMS_SIZE % PAGE_SIZE);
 	BUILD_BUG_ON(TASK_ENTRIES_SIZE % PAGE_SIZE);
 
 	restore_task_vma_len   = round_up(sizeof(*task_args), PAGE_SIZE);
@@ -2222,7 +2218,7 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core)
 	restore_bootstrap_len = restorer_len +
 				restore_task_vma_len +
 				restore_thread_vma_len +
-				SHMEMS_SIZE + TASK_ENTRIES_SIZE +
+				TASK_ENTRIES_SIZE +
 				rst_mem_remap_size();
 
 	/*
@@ -2303,12 +2299,6 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core)
 	 */
 
 	mem += restore_task_vma_len + restore_thread_vma_len;
-	ret = shmem_remap(rst_shmems, mem, SHMEMS_SIZE);
-	if (ret < 0)
-		goto err;
-	task_args->shmems = mem;
-
-	mem += SHMEMS_SIZE;
 	ret = shmem_remap(task_entries, mem, TASK_ENTRIES_SIZE);
 	if (ret < 0)
 		goto err;
@@ -2324,6 +2314,9 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core)
 	if (rst_mem_remap(mem))
 		goto err;
 
+	task_args->shmems = rst_mem_remap_ptr(rst_shmems, RM_SHREMAP);
+	task_args->nr_shmems = nr_shmems;
+
 	task_args->nr_vmas = rst_vmas.nr;
 	task_args->tgt_vmas = rst_mem_remap_ptr(tgt_vmas, RM_PRIVATE);
 

include/restorer.h

@@ -105,7 +105,8 @@ struct task_restore_core_args {
 	int				nr_zombies;
 	thread_restore_fcall_t		clone_restore_fn;	/* helper address for clone() call */
 	struct thread_restore_args	*thread_args;		/* array of thread arguments */
-	struct shmems			*shmems;
+	struct shmem_info		*shmems;
+	unsigned int			nr_shmems;
 	struct task_entries		*task_entries;
 	void				*rst_mem;
 	unsigned long			rst_mem_size;
@@ -150,8 +151,6 @@ struct task_restore_core_args {
 	unsigned long			vdso_rt_parked_at;	/* safe place to keep vdso */
 } __aligned(sizeof(long));
 
-#define SHMEMS_SIZE	4096
-
 #define RESTORE_ALIGN_STACK(start, size)	\
 	(ALIGN((start) + (size) - sizeof(long), sizeof(long)))
 
@@ -177,11 +176,6 @@ struct shmem_info {
 	futex_t		lock;
 };
 
-struct shmems {
-	int			nr_shmems;
-	struct shmem_info	entries[0];
-};
-
 #define TASK_ENTRIES_SIZE 4096
 
 enum {
@@ -208,16 +202,14 @@ struct task_entries {
 };
 
 static always_inline struct shmem_info *
-find_shmem(struct shmems *shmems, unsigned long shmid)
+find_shmem(struct shmem_info *shmems, int nr, unsigned long shmid)
 {
 	struct shmem_info *si;
 	int i;
 
-	for (i = 0; i < shmems->nr_shmems; i++) {
-		si = &shmems->entries[i];
+	for (i = 0, si = shmems; i < nr; i++, si++)
 		if (si->shmid == shmid)
 			return si;
-	}
 
 	return NULL;
 }

include/shmem.h

@@ -8,8 +8,8 @@ int prepare_shmem_restore(void);
 void show_saved_shmems(void);
 int get_shmem_fd(int pid, VmaEntry *vi);
 
-struct shmems;
-extern struct shmems *rst_shmems;
+extern unsigned long nr_shmems;
+extern unsigned int rst_shmems;
 
 int cr_dump_shmem(void);
 int add_shmem_area(pid_t pid, VmaEntry *vma);

pie/restorer.c

@@ -704,7 +704,7 @@ long __export_restore_task(struct task_restore_core_args *args)
 		if (vma_entry_is(vma_entry, VMA_ANON_SHARED)) {
 			struct shmem_info *entry;
 
-			entry = find_shmem(args->shmems,
+			entry = find_shmem(args->shmems, args->nr_shmems,
 						  vma_entry->shmid);
 			if (entry && entry->pid == my_pid &&
 			    entry->start == vma_entry->start)
@@ -746,11 +746,7 @@ long __export_restore_task(struct task_restore_core_args *args)
 		}
 	}
 
-	ret = sys_munmap(args->shmems, SHMEMS_SIZE);
-	if (ret < 0) {
-		pr_err("Can't unmap shmem %ld\n", ret);
-		goto core_restore_end;
-	}
+	ret = 0;
 
 	/*
 	 * Tune up the task fields.

shmem.c

@@ -8,31 +8,40 @@
 #include "restorer.h"
 #include "page-pipe.h"
 #include "page-xfer.h"
+#include "rst-malloc.h"
 #include "protobuf.h"
 #include "protobuf/pagemap.pb-c.h"
 
-struct shmems *rst_shmems;
+unsigned long nr_shmems;
+unsigned int rst_shmems;
 
 void show_saved_shmems(void)
 {
 	int i;
+	struct shmem_info *si;
 
 	pr_info("\tSaved shmems:\n");
-
-	for (i = 0; i < rst_shmems->nr_shmems; i++)
+	si = rst_mem_remap_ptr(rst_shmems, RM_SHREMAP);
+	for (i = 0; i < nr_shmems; i++, si++)
 		pr_info("\t\tstart: 0x%016lx shmid: 0x%lx pid: %d\n",
-			rst_shmems->entries[i].start,
-			rst_shmems->entries[i].shmid,
-			rst_shmems->entries[i].pid);
+				si->start, si->shmid, si->pid);
+}
+
+
+static struct shmem_info *find_shmem_by_id(unsigned long id)
+{
+	struct shmem_info *si;
+
+	si = rst_mem_remap_ptr(rst_shmems, RM_SHREMAP);
+	return find_shmem(si, nr_shmems, id);
 }
 
 static int collect_shmem(int pid, VmaEntry *vi)
 {
-	int nr_shmems = rst_shmems->nr_shmems;
 	unsigned long size = vi->pgoff + vi->end - vi->start;
 	struct shmem_info *si;
 
-	si = find_shmem(rst_shmems, vi->shmid);
+	si = find_shmem_by_id(vi->shmid);
 	if (si) {
 
 		if (si->size < size)
@@ -54,18 +63,13 @@ static int collect_shmem(int pid, VmaEntry *vi)
 		return 0;
 	}
 
-	if ((nr_shmems + 1) * sizeof(struct shmem_info) +
-					sizeof (struct shmems) >= SHMEMS_SIZE) {
-		pr_err("OOM storing shmems\n");
+	si = rst_mem_alloc(sizeof(struct shmem_info), RM_SHREMAP);
+	if (!si)
 		return -1;
-	}
 
 	pr_info("Add new shmem 0x%"PRIx64" (0x0160x%"PRIx64"-0x0160x%"PRIx64")\n",
 				vi->shmid, vi->start, vi->end);
 
-	si = &rst_shmems->entries[nr_shmems];
-	rst_shmems->nr_shmems++;
-
 	si->start = vi->start;
 	si->end	  = vi->end;
 	si->shmid = vi->shmid;
@@ -73,6 +77,7 @@ static int collect_shmem(int pid, VmaEntry *vi)
 	si->size  = size;
 	si->fd    = -1;
 
+	nr_shmems++;
 	futex_init(&si->lock);
 
 	return 0;
@@ -203,7 +208,7 @@ int get_shmem_fd(int pid, VmaEntry *vi)
 	void *addr;
 	int f;
 
-	si = find_shmem(rst_shmems, vi->shmid);
+	si = find_shmem_by_id(vi->shmid);
 	pr_info("Search for 0x%016"PRIx64" shmem 0x%"PRIx64" %p/%d\n", vi->start, vi->shmid, si, si ? si->pid : -1);
 	if (!si) {
 		pr_err("Can't find my shmem 0x%016"PRIx64"\n", vi->start);
@@ -248,18 +253,6 @@ int get_shmem_fd(int pid, VmaEntry *vi)
 	return f;
 }
 
-int prepare_shmem_restore(void)
-{
-	rst_shmems = mmap(NULL, SHMEMS_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, 0, 0);
-	if (rst_shmems == MAP_FAILED) {
-		pr_perror("Can't map shmem");
-		return -1;
-	}
-
-	rst_shmems->nr_shmems = 0;
-	return 0;
-}
-
 struct shmem_info_dump {
 	unsigned long	size;
 	unsigned long	shmid;