[Devel] [RFC v14][PATCH 04/54] General infrastructure for checkpoint restart
Oren Laadan
orenl at cs.columbia.edu
Tue Apr 28 16:23:34 PDT 2009
Add those interfaces, as well as helpers needed to easily manage the
file format. The code is roughly broken out as follows:
checkpoint/sys.c - user/kernel data transfer, as well as setup of the
CR context (a per-checkpoint data structure for housekeeping)
checkpoint/checkpoint.c - output wrappers and basic checkpoint handling
checkpoint/restart.c - input wrappers and basic restart handling
For now, we can only checkpoint the 'current' task ("self" checkpoint),
and the 'pid' argument to to the syscall is ignored.
Patches to add the per-architecture support as well as the actual
work to do the memory checkpoint follow in subsequent patches.
Changelog[v14]:
- Cleanup interface to get/put hdr buffers
- Merge checkpoint and restart code into a single file (per subsystem)
- Take uts_sem around access to uts->{release,version,machine}
- Embed ckpt_hdr in all ckpt_hdr_...., cleanup read/write helpers
- Define sys_checkpoint(0,...) as asking for a self-checkpoint (Serge)
- Revert use of 'pr_fmt' to avoid tainting whom includes us (Nathan Lynch)
- Explicitly indicate length of UTS fields in header
- Discard field 'h->parent' from ckpt_hdr
Changelog[v12]:
- ckpt_kwrite/ckpt_kread() again use vfs_read(), vfs_write() (safer)
- Split ckpt_write/ckpt_read() to two parts: _ckpt_write/read() helper
- Befriend with sparse : explicit conversion to 'void __user *'
- Redfine 'pr_fmt' instead of using special ckpt_debug()
Changelog[v10]:
- add ckpt_write_buffer(), ckpt_read_buffer() and ckpt_read_buf_type()
- force end-of-string in ckpt_read_string() (fix possible DoS)
Changelog[v9]:
- ckpt_kwrite/ckpt_kread() use file->f_op->write() directly
- Drop ckpt_uwrite/ckpt_uread() since they aren't used anywhere
Changelog[v6]:
- Balance all calls to ckpt_hbuf_get() with matching ckpt_hbuf_put()
(although it's not really needed)
Changelog[v5]:
- Rename headers files s/ckpt/checkpoint/
Changelog[v2]:
- Added utsname->{release,version,machine} to checkpoint header
- Pad header structures to 64 bits to ensure compatibility
Signed-off-by: Oren Laadan <orenl at cs.columbia.edu>
---
Makefile | 2 +-
checkpoint/Makefile | 3 +-
checkpoint/checkpoint.c | 177 ++++++++++++++++++++++
checkpoint/process.c | 97 ++++++++++++
checkpoint/restart.c | 298 ++++++++++++++++++++++++++++++++++++++
checkpoint/sys.c | 281 +++++++++++++++++++++++++++++++++++-
include/linux/checkpoint.h | 82 +++++++++++
include/linux/checkpoint_hdr.h | 103 +++++++++++++
include/linux/checkpoint_types.h | 35 +++++
include/linux/magic.h | 4 +
lib/Kconfig.debug | 13 ++
11 files changed, 1088 insertions(+), 7 deletions(-)
create mode 100644 checkpoint/checkpoint.c
create mode 100644 checkpoint/process.c
create mode 100644 checkpoint/restart.c
create mode 100644 include/linux/checkpoint.h
create mode 100644 include/linux/checkpoint_hdr.h
create mode 100644 include/linux/checkpoint_types.h
diff --git a/Makefile b/Makefile
index 9e5dc8f..f278909 100644
--- a/Makefile
+++ b/Makefile
@@ -646,7 +646,7 @@ export mod_strip_cmd
ifeq ($(KBUILD_EXTMOD),)
-core-y += kernel/ mm/ fs/ ipc/ security/ crypto/ block/
+core-y += kernel/ mm/ fs/ ipc/ security/ crypto/ block/ checkpoint/
vmlinux-dirs := $(patsubst %/,%,$(filter %/, $(init-y) $(init-m) \
$(core-y) $(core-m) $(drivers-y) $(drivers-m) \
diff --git a/checkpoint/Makefile b/checkpoint/Makefile
index 8a32c6f..5d2c083 100644
--- a/checkpoint/Makefile
+++ b/checkpoint/Makefile
@@ -2,4 +2,5 @@
# Makefile for linux checkpoint/restart.
#
-obj-$(CONFIG_CHECKPOINT) += sys.o
+obj-$(CONFIG_CHECKPOINT) += sys.o checkpoint.o restart.o \
+ process.o
diff --git a/checkpoint/checkpoint.c b/checkpoint/checkpoint.c
new file mode 100644
index 0000000..6ac3571
--- /dev/null
+++ b/checkpoint/checkpoint.c
@@ -0,0 +1,177 @@
+/*
+ * Checkpoint logic and helpers
+ *
+ * Copyright (C) 2008-2009 Oren Laadan
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of the Linux
+ * distribution for more details.
+ */
+
+/* default debug level for output */
+#define CKPT_DFLAG CKPT_DSYS
+
+#include <linux/version.h>
+#include <linux/time.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/dcache.h>
+#include <linux/mount.h>
+#include <linux/utsname.h>
+#include <linux/magic.h>
+#include <linux/checkpoint.h>
+#include <linux/checkpoint_hdr.h>
+
+/* unique checkpoint identifier (FIXME: should be per-container ?) */
+static atomic_t ctx_count = ATOMIC_INIT(0);
+
+/**
+ * ckpt_write_obj - write an object
+ * @ctx: checkpoint context
+ * @h: object descriptor
+ */
+int ckpt_write_obj(struct ckpt_ctx *ctx, struct ckpt_hdr *h)
+{
+ _ckpt_debug(CKPT_DRW, "type %d len %d\n", h->type, h->len);
+ return ckpt_kwrite(ctx, h, h->len);
+}
+
+/**
+ * ckpt_write_obj_type - write an object (from a pointer)
+ * @ctx: checkpoint context
+ * @ptr: buffer pointer
+ * @len: buffer size
+ * @type: desired type
+ */
+int ckpt_write_obj_type(struct ckpt_ctx *ctx, void *ptr, int len, int type)
+{
+ struct ckpt_hdr *h;
+ int ret;
+
+ h = ckpt_hdr_get(ctx, sizeof(*h));
+ if (!h)
+ return -ENOMEM;
+
+ h->type = type;
+ h->len = len + sizeof(*h);
+
+ _ckpt_debug(CKPT_DRW, "type %d len %d\n", h->type, h->len);
+ ret = ckpt_kwrite(ctx, h, sizeof(*h));
+ if (ret < 0)
+ goto out;
+ ret = ckpt_kwrite(ctx, ptr, len);
+ out:
+ _ckpt_hdr_put(ctx, h, sizeof(*h));
+ return ret;
+}
+
+/**
+ * ckpt_write_buffer - write an object of type buffer
+ * @ctx: checkpoint context
+ * @ptr: buffer pointer
+ * @len: buffer size
+ */
+int ckpt_write_buffer(struct ckpt_ctx *ctx, void *ptr, int len)
+{
+ return ckpt_write_obj_type(ctx, ptr, len, CKPT_HDR_BUFFER);
+}
+
+/**
+ * ckpt_write_string - write an object of type string
+ * @ctx: checkpoint context
+ * @str: string pointer
+ * @len: string length
+ */
+int ckpt_write_string(struct ckpt_ctx *ctx, char *str, int len)
+{
+ return ckpt_write_obj_type(ctx, str, len, CKPT_HDR_STRING);
+}
+
+/***********************************************************************
+ * Checkpoint
+ */
+
+/* write the checkpoint header */
+static int checkpoint_write_header(struct ckpt_ctx *ctx)
+{
+ struct ckpt_hdr_header *h;
+ struct new_utsname *uts;
+ struct timeval ktv;
+ int ret;
+
+ h = ckpt_hdr_get_type(ctx, sizeof(*h), CKPT_HDR_HEADER);
+ if (!h)
+ return -ENOMEM;
+
+ do_gettimeofday(&ktv);
+ uts = utsname();
+
+ h->magic = CHECKPOINT_MAGIC_HEAD;
+ h->major = (LINUX_VERSION_CODE >> 16) & 0xff;
+ h->minor = (LINUX_VERSION_CODE >> 8) & 0xff;
+ h->patch = (LINUX_VERSION_CODE) & 0xff;
+
+ h->rev = CKPT_VERSION;
+
+ h->flags = ctx->flags;
+ h->time = ktv.tv_sec;
+
+ h->uts_release_len = sizeof(uts->release);
+ h->uts_version_len = sizeof(uts->version);
+ h->uts_machine_len = sizeof(uts->machine);
+
+ ret = ckpt_write_obj(ctx, (struct ckpt_hdr *) h);
+ ckpt_hdr_put(ctx, h);
+ if (ret < 0)
+ return ret;
+
+ down_read(&uts_sem);
+ ret = ckpt_write_buffer(ctx, uts->release, sizeof(uts->release));
+ if (ret < 0)
+ goto up;
+ ret = ckpt_write_buffer(ctx, uts->version, sizeof(uts->version));
+ if (ret < 0)
+ goto up;
+ ret = ckpt_write_buffer(ctx, uts->machine, sizeof(uts->machine));
+ up:
+ up_read(&uts_sem);
+ return ret;
+}
+
+/* write the checkpoint trailer */
+static int checkpoint_write_tail(struct ckpt_ctx *ctx)
+{
+ struct ckpt_hdr_tail *h;
+ int ret;
+
+ h = ckpt_hdr_get_type(ctx, sizeof(*h), CKPT_HDR_TAIL);
+ if (!h)
+ return -ENOMEM;
+
+ h->magic = CHECKPOINT_MAGIC_TAIL;
+
+ ret = ckpt_write_obj(ctx, (struct ckpt_hdr *) h);
+ ckpt_hdr_put(ctx, h);
+ return ret;
+}
+
+int do_checkpoint(struct ckpt_ctx *ctx, pid_t pid)
+{
+ int ret;
+
+ ret = checkpoint_write_header(ctx);
+ if (ret < 0)
+ goto out;
+ ret = checkpoint_task(ctx, current);
+ if (ret < 0)
+ goto out;
+ ret = checkpoint_write_tail(ctx);
+ if (ret < 0)
+ goto out;
+
+ /* on success, return (unique) checkpoint identifier */
+ ctx->crid = atomic_inc_return(&ctx_count);
+ ret = ctx->crid;
+ out:
+ return ret;
+}
diff --git a/checkpoint/process.c b/checkpoint/process.c
new file mode 100644
index 0000000..bf7545e
--- /dev/null
+++ b/checkpoint/process.c
@@ -0,0 +1,97 @@
+/*
+ * Checkpoint task structure
+ *
+ * Copyright (C) 2008-2009 Oren Laadan
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of the Linux
+ * distribution for more details.
+ */
+
+/* default debug level for output */
+#define CKPT_DFLAG CKPT_DSYS
+
+#include <linux/sched.h>
+#include <linux/checkpoint.h>
+#include <linux/checkpoint_hdr.h>
+
+/***********************************************************************
+ * Checkpoint
+ */
+
+/* dump the task_struct of a given task */
+static int checkpoint_task_struct(struct ckpt_ctx *ctx, struct task_struct *t)
+{
+ struct ckpt_hdr_task *h;
+ int ret;
+
+ h = ckpt_hdr_get_type(ctx, sizeof(*h), CKPT_HDR_TASK);
+ if (!h)
+ return -ENOMEM;
+
+ h->state = t->state;
+ h->exit_state = t->exit_state;
+ h->exit_code = t->exit_code;
+ h->exit_signal = t->exit_signal;
+
+ h->task_comm_len = TASK_COMM_LEN;
+
+ /* FIXME: save remaining relevant task_struct fields */
+
+ ret = ckpt_write_obj(ctx, (struct ckpt_hdr *) h);
+ ckpt_hdr_put(ctx, h);
+ if (ret < 0)
+ return ret;
+
+ return ckpt_write_string(ctx, t->comm, TASK_COMM_LEN);
+}
+
+/* dump the entire state of a given task */
+int checkpoint_task(struct ckpt_ctx *ctx, struct task_struct *t)
+{
+ int ret;
+
+ ret = checkpoint_task_struct(ctx, t);
+ ckpt_debug("ret %d\n", ret);
+
+ return ret;
+}
+
+/***********************************************************************
+ * Restart
+ */
+
+/* read the task_struct into the current task */
+static int restore_task_struct(struct ckpt_ctx *ctx)
+{
+ struct ckpt_hdr_task *h;
+ struct task_struct *t = current;
+ int ret;
+
+ h = ckpt_read_obj_type(ctx, sizeof(*h), CKPT_HDR_TASK);
+ if (IS_ERR(h))
+ return PTR_ERR(h);
+
+ ret = -EINVAL;
+ if (h->task_comm_len > TASK_COMM_LEN)
+ goto out;
+
+ memset(t->comm, 0, TASK_COMM_LEN);
+ ret = _ckpt_read_string(ctx, t->comm, h->task_comm_len);
+
+ /* FIXME: restore remaining relevant task_struct fields */
+ out:
+ ckpt_hdr_put(ctx, h);
+ return ret;
+}
+
+/* read the entire state of the current task */
+int restore_task(struct ckpt_ctx *ctx)
+{
+ int ret;
+
+ ret = restore_task_struct(ctx);
+ ckpt_debug("ret %d\n", ret);
+
+ return ret;
+}
diff --git a/checkpoint/restart.c b/checkpoint/restart.c
new file mode 100644
index 0000000..d71c0f0
--- /dev/null
+++ b/checkpoint/restart.c
@@ -0,0 +1,298 @@
+/*
+ * Restart logic and helpers
+ *
+ * Copyright (C) 2008-2009 Oren Laadan
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of the Linux
+ * distribution for more details.
+ */
+
+/* default debug level for output */
+#define CKPT_DFLAG CKPT_DSYS
+
+#include <linux/version.h>
+#include <linux/sched.h>
+#include <linux/file.h>
+#include <linux/magic.h>
+#include <linux/utsname.h>
+#include <linux/checkpoint.h>
+#include <linux/checkpoint_hdr.h>
+
+/**
+ * _ckpt_read_obj - read an object (ckpt_hdr followed by payload)
+ * @ctx: checkpoint context
+ * @h: desired ckpt_hdr
+ * @ptr: desired buffer
+ * @len: desired payload length (if 0, flexible)
+ * @max: maximum payload length
+ *
+ * Return: new buffer allocated on success, error pointer otherwise
+ */
+static int _ckpt_read_obj(struct ckpt_ctx *ctx, struct ckpt_hdr *h,
+ void *ptr, int len, int max)
+{
+ int ret;
+
+ ret = ckpt_kread(ctx, h, sizeof(*h));
+ if (ret < 0)
+ return ret;
+ _ckpt_debug(CKPT_DRW, "type %d len %d(%d,%d)\n",
+ h->type, h->len, len, max);
+ if (h->len < sizeof(*h))
+ return -EINVAL;
+ /* if len specified, enforce, else if maximum specified, enforce */
+ if ((len && h->len != len) || (!len && max && h->len > max))
+ return -EINVAL;
+
+ return ckpt_kread(ctx, ptr, h->len - sizeof(struct ckpt_hdr));
+}
+
+/**
+ * _ckpt_read_nbuffer - read an object of type buffer (variable length)
+ * @ctx: checkpoint context
+ * @ptr: provided buffer
+ * @len: buffer length
+ *
+ * Returns: actual buffer length (bounded by @len)
+ */
+int _ckpt_read_nbuffer(struct ckpt_ctx *ctx, void *ptr, int len)
+{
+ struct ckpt_hdr h;
+ int ret;
+
+ BUG_ON(!len);
+
+ len += sizeof(struct ckpt_hdr);
+ ret = _ckpt_read_obj(ctx, &h, ptr, 0, len);
+ if (ret < 0)
+ return ret;
+ _ckpt_debug(CKPT_DRW, "type %d len %d\n", h.type, h.len);
+ if (h.type != CKPT_HDR_BUFFER)
+ return -EINVAL;
+ return h.len;
+}
+
+/**
+ * _ckpt_read_buffer - read an object of type buffer (set length)
+ * @ctx: checkpoint context
+ * @ptr: provided buffer
+ * @len: buffer length
+ */
+int _ckpt_read_buffer(struct ckpt_ctx *ctx, void *ptr, int len)
+{
+ struct ckpt_hdr h;
+ int ret;
+
+ BUG_ON(!len);
+
+ len += sizeof(struct ckpt_hdr);
+ ret = _ckpt_read_obj(ctx, &h, ptr, len, len);
+ if (ret < 0)
+ return ret;
+ if (h.type != CKPT_HDR_BUFFER)
+ return -EINVAL;
+ return 0;
+}
+
+/**
+ * _ckpt_read_string - read an object of type string (set length)
+ * @ctx: checkpoint context
+ * @ptr: provided buffer
+ * @len: string length
+ */
+int _ckpt_read_string(struct ckpt_ctx *ctx, void *ptr, int len)
+{
+ struct ckpt_hdr h;
+ int ret;
+
+ BUG_ON(!len);
+
+ ret = _ckpt_read_obj(ctx, &h, ptr, len + sizeof(h), len + sizeof(h));
+ if (ret < 0)
+ return ret;
+ if (h.type != CKPT_HDR_STRING)
+ return -EINVAL;
+
+ ((char *) ptr)[len - 1] = '\0'; /* always play it safe */
+ return 0;
+}
+
+/**
+ * ckpt_read_obj - allocate and read an object (ckpt_hdr followed by payload)
+ * @ctx: checkpoint context
+ * @h: object descriptor
+ * @len: desired payload length (if 0, flexible)
+ * @max: maximum payload length
+ *
+ * Return: new buffer allocated on success, error pointer otherwise
+ */
+static void *ckpt_read_obj(struct ckpt_ctx *ctx, int len, int max)
+{
+ struct ckpt_hdr hh;
+ struct ckpt_hdr *h;
+ int ret;
+
+ ret = ckpt_kread(ctx, &hh, sizeof(hh));
+ if (ret < 0)
+ return ERR_PTR(ret);
+ _ckpt_debug(CKPT_DRW, "type %d len %d(%d,%d)\n",
+ hh.type, hh.len, len, max);
+ if (hh.len < sizeof(*h))
+ return ERR_PTR(-EINVAL);
+ /* if len specified, enforce, else if maximum specified, enforce */
+ if ((len && hh.len != len) || (!len && max && hh.len > max))
+ return ERR_PTR(-EINVAL);
+
+ h = ckpt_hdr_get(ctx, hh.len);
+ if (!h)
+ return ERR_PTR(-ENOMEM);
+
+ *h = hh; /* yay ! */
+
+ ret = ckpt_kread(ctx, (h + 1), hh.len - sizeof(struct ckpt_hdr));
+ if (ret < 0) {
+ ckpt_hdr_put(ctx, h);
+ h = ERR_PTR(ret);
+ }
+
+ return h;
+}
+
+/**
+ * ckpt_read_obj_type - allocate and read an object of some type
+ * @ctx: checkpoint context
+ * @len: desired object length
+ * @type: desired object type
+ *
+ * Return: new buffer allocated on success, error pointer otherwise
+ */
+void *ckpt_read_obj_type(struct ckpt_ctx *ctx, int len, int type)
+{
+ struct ckpt_hdr *h;
+
+ BUG_ON(!len);
+
+ h = ckpt_read_obj(ctx, len, len);
+ if (IS_ERR(h))
+ return h;
+
+ if (h->type != type) {
+ ckpt_hdr_put(ctx, h);
+ h = ERR_PTR(-EINVAL);
+ }
+
+ return h;
+}
+
+/**
+ * ckpt_read_buf_type - allocate and read an object of some type (flxible)
+ * @ctx: checkpoint context
+ * @len: maximum object length
+ * @type: desired object type
+ *
+ * This differs from ckpt_read_obj_type() in that the length of the
+ * incoming object is flexible (up to the maximum specified by @len),
+ * as determined by the ckpt_hdr data.
+ *
+ * Return: new buffer allocated on success, error pointer otherwise
+ */
+void *ckpt_read_buf_type(struct ckpt_ctx *ctx, int len, int type)
+{
+ struct ckpt_hdr *h;
+
+ BUG_ON(!len);
+
+ h = ckpt_read_obj(ctx, len, len);
+ if (IS_ERR(h))
+ return h;
+
+ if (h->type != type) {
+ ckpt_hdr_put(ctx, h);
+ h = ERR_PTR(-EINVAL);
+ }
+
+ return h;
+}
+
+/***********************************************************************
+ * Restart
+ */
+
+/* read the checkpoint header */
+static int restore_read_header(struct ckpt_ctx *ctx)
+{
+ struct ckpt_hdr_header *h;
+ struct new_utsname *uts = NULL;
+ int ret;
+
+ h = ckpt_read_obj_type(ctx, sizeof(*h), CKPT_HDR_HEADER);
+ if (IS_ERR(h))
+ return PTR_ERR(h);
+
+ ret = -EINVAL;
+ if (h->magic != CHECKPOINT_MAGIC_HEAD || h->rev != CKPT_VERSION ||
+ h->major != ((LINUX_VERSION_CODE >> 16) & 0xff) ||
+ h->minor != ((LINUX_VERSION_CODE >> 8) & 0xff) ||
+ h->patch != ((LINUX_VERSION_CODE) & 0xff))
+ goto out;
+ if (h->flags & ~CKPT_CTX_CHECKPOINT)
+ goto out;
+ if (h->uts_release_len != sizeof(uts->release) ||
+ h->uts_version_len != sizeof(uts->version) ||
+ h->uts_machine_len != sizeof(uts->machine))
+ goto out;
+
+ ret = -ENOMEM;
+ uts = kmalloc(sizeof(*uts), GFP_KERNEL);
+ if (!uts)
+ goto out;
+
+ ctx->oflags = h->flags;
+
+ /* FIX: verify compatibility of release, version and machine */
+ ret = _ckpt_read_buffer(ctx, uts->release, sizeof(uts->release));
+ if (ret < 0)
+ goto out;
+ ret = _ckpt_read_buffer(ctx, uts->version, sizeof(uts->version));
+ if (ret < 0)
+ goto out;
+ ret = _ckpt_read_buffer(ctx, uts->machine, sizeof(uts->machine));
+ out:
+ kfree(uts);
+ ckpt_hdr_put(ctx, h);
+ return ret;
+}
+
+/* read the checkpoint trailer */
+static int restore_read_tail(struct ckpt_ctx *ctx)
+{
+ struct ckpt_hdr_tail *h;
+ int ret = 0;
+
+ h = ckpt_read_obj_type(ctx, sizeof(*h), CKPT_HDR_TAIL);
+ if (IS_ERR(h))
+ return PTR_ERR(h);
+
+ if (h->magic != CHECKPOINT_MAGIC_TAIL)
+ ret = -EINVAL;
+
+ ckpt_hdr_put(ctx, h);
+ return ret;
+}
+
+int do_restart(struct ckpt_ctx *ctx, pid_t pid)
+{
+ int ret;
+
+ ret = restore_read_header(ctx);
+ if (ret < 0)
+ return ret;
+ ret = restore_task(ctx);
+ if (ret < 0)
+ return ret;
+ ret = restore_read_tail(ctx);
+
+ /* on success, adjust the return value if needed [TODO] */
+ return ret;
+}
diff --git a/checkpoint/sys.c b/checkpoint/sys.c
index 375129c..a99cd51 100644
--- a/checkpoint/sys.c
+++ b/checkpoint/sys.c
@@ -1,15 +1,233 @@
/*
* Generic container checkpoint-restart
*
- * Copyright (C) 2008 Oren Laadan
+ * Copyright (C) 2008-2009 Oren Laadan
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file COPYING in the main directory of the Linux
* distribution for more details.
*/
+/* default debug level for output */
+#define CKPT_DFLAG CKPT_DSYS
+
#include <linux/sched.h>
#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/uaccess.h>
+#include <linux/capability.h>
+#include <linux/checkpoint.h>
+
+/*
+ * Helpers to write(read) from(to) kernel space to(from) the checkpoint
+ * image file descriptor (similar to how a core-dump is performed).
+ *
+ * ckpt_kwrite() - write a kernel-space buffer to the checkpoint image
+ * ckpt_kread() - read from the checkpoint image to a kernel-space buffer
+ */
+
+static inline int _ckpt_kwrite(struct file *file, void *addr, int count)
+{
+ void __user *uaddr = (__force void __user *) addr;
+ ssize_t nwrite;
+ int nleft;
+
+ for (nleft = count; nleft; nleft -= nwrite) {
+ loff_t pos = file_pos_read(file);
+ nwrite = vfs_write(file, uaddr, nleft, &pos);
+ file_pos_write(file, pos);
+ if (nwrite < 0) {
+ if (nwrite == -EAGAIN)
+ nwrite = 0;
+ else
+ return nwrite;
+ }
+ uaddr += nwrite;
+ }
+ return 0;
+}
+
+int ckpt_kwrite(struct ckpt_ctx *ctx, void *addr, int count)
+{
+ mm_segment_t fs;
+ int ret;
+
+ fs = get_fs();
+ set_fs(KERNEL_DS);
+ ret = _ckpt_kwrite(ctx->file, addr, count);
+ set_fs(fs);
+
+ ctx->total += count;
+ return ret;
+}
+
+static inline int _ckpt_kread(struct file *file, void *addr, int count)
+{
+ void __user *uaddr = (__force void __user *) addr;
+ ssize_t nread;
+ int nleft;
+
+ for (nleft = count; nleft; nleft -= nread) {
+ loff_t pos = file_pos_read(file);
+ nread = vfs_read(file, uaddr, nleft, &pos);
+ file_pos_write(file, pos);
+ if (nread <= 0) {
+ if (nread == -EAGAIN) {
+ nread = 0;
+ continue;
+ } else if (nread == 0)
+ nread = -EPIPE; /* unexecpted EOF */
+ return nread;
+ }
+ uaddr += nread;
+ }
+ return 0;
+}
+
+int ckpt_kread(struct ckpt_ctx *ctx, void *addr, int count)
+{
+ mm_segment_t fs;
+ int ret;
+
+ fs = get_fs();
+ set_fs(KERNEL_DS);
+ ret = _ckpt_kread(ctx->file , addr, count);
+ set_fs(fs);
+
+ ctx->total += count;
+ return ret;
+}
+
+/*
+ * During checkpoint and restart the code writes outs/reads in data
+ * to/from the checkpoint image from/to a temporary buffer (ctx->hbuf).
+ * Because operations can be nested, use ckpt_hdr_get() to reserve space
+ * in the buffer, then ckpt_hdr_put() when you no longer need that space.
+ *
+ * Checkpoint is performed by a single task, and restart is performed
+ * one task at a time; Thus, we expect that only one thread be using
+ * the ctx->hbuf at a time, so no locking is needed.
+ */
+
+/*
+ * ctx->hbuf is used to hold headers and data of known (or bound),
+ * static sizes. In some cases, multiple headers may be allocated in
+ * a nested manner. The size should accommodate all headers, nested
+ * or not, on all archs.
+ */
+#define CKPT_HBUF_TOTAL (8 * 4096)
+
+/**
+ * ckpt_hdr_get - get a hdr of certain size
+ * @ctx: checkpoint context
+ * @len: desired length
+ *
+ * Returns pointer to header (on hbuf)
+ */
+void *ckpt_hdr_get(struct ckpt_ctx *ctx, int len)
+{
+ void *ptr;
+
+ /*
+ * Since requests depend on logic and static header sizes (not on
+ * user data), space should always suffice, unless someone either
+ * made a structure bigger or call path deeper than expected.
+ */
+ BUG_ON(ctx->hpos + len > CKPT_HBUF_TOTAL);
+ ptr = ctx->hbuf + ctx->hpos;
+ ctx->hpos += len;
+ return ptr;
+}
+
+/**
+ * _ckpt_hdr_put - free a hdr allocated with ckpt_hdr_get
+ * @ctx: checkpoint context
+ * @ptr: header to free
+ * @ptr: header length
+ *
+ * (requiring 'ptr' makes it easily interchangable with kmalloc/kfree
+ */
+void _ckpt_hdr_put(struct ckpt_ctx *ctx, void *ptr, int len)
+{
+ BUG_ON(ctx->hpos < len);
+ ctx->hpos -= len;
+}
+
+/**
+ * ckpt_hdr_put - free a hdr allocated with ckpt_hdr_get
+ * @ctx: checkpoint context
+ * @ptr: header to free
+ *
+ * It is assumed that @ptr begins with a 'struct ckpt_hdr'.
+ */
+void ckpt_hdr_put(struct ckpt_ctx *ctx, void *ptr)
+{
+ struct ckpt_hdr *h = ptr;
+ return _ckpt_hdr_put(ctx, ptr, h->len);
+}
+
+/**
+ * ckpt_hdr_get_type - get a hdr of certain size
+ * @ctx: checkpoint context
+ * @len: number of bytes to reserve
+ *
+ * Returns pointer to reserved space on hbuf
+ */
+void *ckpt_hdr_get_type(struct ckpt_ctx *ctx, int len, int type)
+{
+ struct ckpt_hdr *h;
+
+ h = ckpt_hdr_get(ctx, len);
+ if (!h)
+ return NULL;
+
+ h->type = type;
+ h->len = len;
+ return h;
+}
+
+
+/*
+ * helpers to manage C/R contexts: allocated for each checkpoint and/or
+ * restart operation, and persists until the operation is completed.
+ */
+
+static void ckpt_ctx_free(struct ckpt_ctx *ctx)
+{
+ if (ctx->file)
+ fput(ctx->file);
+ kfree(ctx->hbuf);
+ kfree(ctx);
+}
+
+static struct ckpt_ctx *ckpt_ctx_alloc(int fd, unsigned long flags)
+{
+ struct ckpt_ctx *ctx;
+ int err;
+
+ ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+ if (!ctx)
+ return ERR_PTR(-ENOMEM);
+
+ ctx->flags = flags;
+
+ err = -EBADF;
+ ctx->file = fget(fd);
+ if (!ctx->file)
+ goto err;
+
+ err = -ENOMEM;
+ ctx->hbuf = kmalloc(CKPT_HBUF_TOTAL, GFP_KERNEL);
+ if (!ctx->hbuf)
+ goto err;
+
+ return ctx;
+
+ err:
+ ckpt_ctx_free(ctx);
+ return ERR_PTR(err);
+}
/**
* sys_checkpoint - checkpoint a container
@@ -22,9 +240,28 @@
*/
asmlinkage long sys_checkpoint(pid_t pid, int fd, unsigned long flags)
{
- pr_debug("sys_checkpoint not implemented yet\n");
- return -ENOSYS;
+ struct ckpt_ctx *ctx;
+ int ret;
+
+ /* no flags for now */
+ if (flags)
+ return -EINVAL;
+
+ if (pid == 0)
+ pid = current->pid;
+ ctx = ckpt_ctx_alloc(fd, flags | CKPT_CTX_CHECKPOINT);
+ if (IS_ERR(ctx))
+ return PTR_ERR(ctx);
+
+ ret = do_checkpoint(ctx, pid);
+
+ if (!ret)
+ ret = ctx->crid;
+
+ ckpt_ctx_free(ctx);
+ return ret;
}
+
/**
* sys_restart - restart a container
* @crid: checkpoint image identifier
@@ -36,6 +273,40 @@ asmlinkage long sys_checkpoint(pid_t pid, int fd, unsigned long flags)
*/
asmlinkage long sys_restart(int crid, int fd, unsigned long flags)
{
- pr_debug("sys_restart not implemented yet\n");
- return -ENOSYS;
+ struct ckpt_ctx *ctx;
+ pid_t pid;
+ int ret;
+
+ /* no flags for now */
+ if (flags)
+ return -EINVAL;
+
+ ctx = ckpt_ctx_alloc(fd, flags | CKPT_CTX_RESTART);
+ if (IS_ERR(ctx))
+ return PTR_ERR(ctx);
+
+ /* FIXME: for now, we use 'crid' as a pid */
+ pid = (pid_t) crid;
+
+ ret = do_restart(ctx, pid);
+
+ ckpt_ctx_free(ctx);
+ return ret;
}
+
+
+/* 'ckpt_debug_level' controls the verbosity level of c/r code */
+#ifdef CONFIG_CHECKPOINT_DEBUG
+
+/* FIX: allow to change during runtime */
+unsigned int __read_mostly ckpt_debug_level = CKPT_DDEFAULT;
+
+static __init int ckpt_debug_setup(char *s)
+{
+ ckpt_debug_level = strict_strtoul(s, NULL, 0);
+ return 0;
+}
+
+__setup("ckpt_debug=", ckpt_debug_setup);
+
+#endif /* CONFIG_CHECKPOINT_DEBUG */
diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
new file mode 100644
index 0000000..1433290
--- /dev/null
+++ b/include/linux/checkpoint.h
@@ -0,0 +1,82 @@
+#ifndef _LINUX_CHECKPOINT_H_
+#define _LINUX_CHECKPOINT_H_
+/*
+ * Generic checkpoint-restart
+ *
+ * Copyright (C) 2008-2009 Oren Laadan
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of the Linux
+ * distribution for more details.
+ */
+
+#include <linux/checkpoint_types.h>
+#include <linux/checkpoint_hdr.h>
+
+extern int ckpt_kwrite(struct ckpt_ctx *ctx, void *buf, int count);
+extern int ckpt_kread(struct ckpt_ctx *ctx, void *buf, int count);
+
+extern void _ckpt_hdr_put(struct ckpt_ctx *ctx, void *ptr, int n);
+extern void ckpt_hdr_put(struct ckpt_ctx *ctx, void *ptr);
+extern void *ckpt_hdr_get(struct ckpt_ctx *ctx, int n);
+extern void *ckpt_hdr_get_type(struct ckpt_ctx *ctx, int n, int type);
+
+extern int ckpt_write_obj(struct ckpt_ctx *ctx, struct ckpt_hdr *h);
+extern int ckpt_write_obj_type(struct ckpt_ctx *ctx,
+ void *ptr, int len, int type);
+extern int ckpt_write_buffer(struct ckpt_ctx *ctx, void *ptr, int len);
+extern int ckpt_write_string(struct ckpt_ctx *ctx, char *str, int len);
+
+extern int _ckpt_read_obj_type(struct ckpt_ctx *ctx,
+ void *ptr, int len, int type);
+extern int _ckpt_read_buffer(struct ckpt_ctx *ctx, void *ptr, int len);
+extern int _ckpt_read_string(struct ckpt_ctx *ctx, void *ptr, int len);
+extern void *ckpt_read_obj_type(struct ckpt_ctx *ctx, int len, int type);
+extern void *ckpt_read_buf_type(struct ckpt_ctx *ctx, int len, int type);
+
+extern int do_checkpoint(struct ckpt_ctx *ctx, pid_t pid);
+extern int do_restart(struct ckpt_ctx *ctx, pid_t pid);
+
+/* task */
+extern int checkpoint_task(struct ckpt_ctx *ctx, struct task_struct *t);
+extern int restore_task(struct ckpt_ctx *ctx);
+
+
+/* debugging flags */
+#define CKPT_DBASE 0x1 /* anything */
+#define CKPT_DSYS 0x2 /* generic (system) */
+#define CKPT_DRW 0x4 /* image read/write */
+
+#define CKPT_DDEFAULT 0x7 /* default debug level */
+
+#ifndef CKPT_DFLAG
+#define CKPT_DFLAG 0x0 /* nothing */
+#endif
+
+#ifdef CONFIG_CHECKPOINT_DEBUG
+extern unsigned int ckpt_debug_level;
+
+/* use this to select a specific debug level */
+#define _ckpt_debug(level, fmt, args...) \
+ do { \
+ if (ckpt_debug_level & (level)) \
+ pr_debug("[%d:c/r:%s] " fmt, \
+ task_pid_vnr(current), \
+ __func__, ## args); \
+ } while (0)
+
+/*
+ * CKPT_DBASE is the base flags, doesn't change
+ * CKPT_DFLAG is to be redfined in each source file
+ */
+#define ckpt_debug(fmt, args...) \
+ _ckpt_debug(CKPT_DBASE | CKPT_DFLAG, fmt, ## args)
+
+#else
+
+#define _ckpt_debug(level, fmt, args...) do { } while (0)
+#define ckpt_debug(fmt, args...) do { } while (0)
+
+#endif /* CONFIG_CHECKPOINT_DEBUG */
+
+#endif /* _LINUX_CHECKPOINT_H_ */
diff --git a/include/linux/checkpoint_hdr.h b/include/linux/checkpoint_hdr.h
new file mode 100644
index 0000000..45378aa
--- /dev/null
+++ b/include/linux/checkpoint_hdr.h
@@ -0,0 +1,103 @@
+#ifndef _CHECKPOINT_CKPT_HDR_H_
+#define _CHECKPOINT_CKPT_HDR_H_
+/*
+ * Generic container checkpoint-restart
+ *
+ * Copyright (C) 2008-2009 Oren Laadan
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of the Linux
+ * distribution for more details.
+ */
+
+#include <linux/types.h>
+#include <linux/utsname.h>
+
+/*
+ * To maintain compatibility between 32-bit and 64-bit architecture flavors,
+ * keep data 64-bit aligned: use padding for structure members, and use
+ * __attribute__((aligned (8))) for the entire structure.
+ *
+ * Quoting Arnd Bergmann:
+ * "This structure has an odd multiple of 32-bit members, which means
+ * that if you put it into a larger structure that also contains 64-bit
+ * members, the larger structure may get different alignment on x86-32
+ * and x86-64, which you might want to avoid. I can't tell if this is
+ * an actual problem here. ... In this case, I'm pretty sure that
+ * sizeof(ckpt_hdr_task) on x86-32 is different from x86-64, since it
+ * will be 32-bit aligned on x86-32."
+ */
+
+/*
+ * header format: 'struct ckpt_hdr' must prefix all other headers. Therfore
+ * when a header is passed around, the information about it (type, size)
+ * is readily available.
+ */
+struct ckpt_hdr {
+ __u32 type;
+ __u32 len;
+} __attribute__((aligned(8)));
+
+/* header types */
+enum {
+ CKPT_HDR_HEADER = 1,
+ CKPT_HDR_BUFFER,
+ CKPT_HDR_STRING,
+
+ CKPT_HDR_TASK = 101,
+ CKPT_HDR_THREAD,
+ CKPT_HDR_CPU,
+
+ CKPT_HDR_MM = 201,
+ CKPT_HDR_VMA,
+ CKPT_HDR_MM_CONTEXT,
+
+ CKPT_HDR_TAIL = 5001
+};
+
+/* checkpoint image header */
+struct ckpt_hdr_header {
+ struct ckpt_hdr h;
+ __u64 magic;
+
+ __u16 major;
+ __u16 minor;
+ __u16 patch;
+ __u16 rev;
+
+ __u64 time; /* when checkpoint taken */
+ __u64 flags; /* checkpoint options */
+
+ __u16 uts_release_len;
+ __u16 uts_version_len;
+ __u16 uts_machine_len;
+ __u16 _padding;
+
+ /*
+ * the header is followed by three strings:
+ * char release[__NEW_UTS_LEN];
+ * char version[__NEW_UTS_LEN];
+ * char machine[__NEW_UTS_LEN];
+ */
+} __attribute__((aligned(8)));
+
+
+/* checkpoint image trailer */
+struct ckpt_hdr_tail {
+ struct ckpt_hdr h;
+ __u64 magic;
+} __attribute__((aligned(8)));
+
+
+/* task data */
+struct ckpt_hdr_task {
+ struct ckpt_hdr h;
+ __u32 state;
+ __u32 exit_state;
+ __u32 exit_code;
+ __u32 exit_signal;
+
+ __u32 task_comm_len;
+} __attribute__((aligned(8)));
+
+#endif /* _CHECKPOINT_CKPT_HDR_H_ */
diff --git a/include/linux/checkpoint_types.h b/include/linux/checkpoint_types.h
new file mode 100644
index 0000000..b04090f
--- /dev/null
+++ b/include/linux/checkpoint_types.h
@@ -0,0 +1,35 @@
+#ifndef _LINUX_CHECKPOINT_TYPES_H_
+#define _LINUX_CHECKPOINT_TYPES_H_
+/*
+ * Generic checkpoint-restart
+ *
+ * Copyright (C) 2008-2009 Oren Laadan
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of the Linux
+ * distribution for more details.
+ */
+
+#define CKPT_VERSION 1
+
+struct ckpt_ctx {
+ int crid; /* unique checkpoint id */
+
+ pid_t root_pid; /* container identifier */
+
+ unsigned long flags;
+ unsigned long oflags; /* restart: old flags */
+
+ struct file *file;
+ int total; /* total read/written */
+
+ void *hbuf; /* temporary buffer for headers */
+ int hpos; /* position in headers buffer */
+};
+
+/* ckpt_ctx: flags */
+#define CKPT_CTX_CHECKPOINT 0x1
+#define CKPT_CTX_RESTART 0x2
+
+
+#endif /* _LINUX_CHECKPOINT_TYPES_H_ */
diff --git a/include/linux/magic.h b/include/linux/magic.h
index 5b4e28b..73a9d02 100644
--- a/include/linux/magic.h
+++ b/include/linux/magic.h
@@ -50,4 +50,8 @@
#define INOTIFYFS_SUPER_MAGIC 0x2BAD1DEA
#define STACK_END_MAGIC 0x57AC6E9D
+
+#define CHECKPOINT_MAGIC_HEAD 0x00feed0cc0a2d200LL
+#define CHECKPOINT_MAGIC_TAIL 0x002d2a0cc0deef00LL
+
#endif /* __LINUX_MAGIC_H__ */
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index c6e854f..68b4eab 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -962,6 +962,19 @@ config DMA_API_DEBUG
This option causes a performance degredation. Use only if you want
to debug device drivers. If unsure, say N.
+config CHECKPOINT_DEBUG
+ bool "Checkpoint/restart debugging (EXPERIMENTAL)"
+ depends on CHECKPOINT
+ default y
+ help
+ This options turns on the debugging output of checkpoint/restart.
+ The level of verbosity is controlled by 'ckpt_debug_level' and can
+ be set at boot time with "ckpt_debug=" option.
+
+ Turning this option off will reduce the size of the c/r code. If
+ turned on, it is unlikely to incur visible overhead if the debug
+ level is set to zero.
+
source "samples/Kconfig"
source "lib/Kconfig.kgdb"
--
1.5.4.3
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