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Subject[RFC v16][PATCH 06/43] c/r: x86_32 support for checkpoint/restart
Date
Add logic to save and restore architecture specific state, including
thread-specific state, CPU registers and FPU state.

In addition, architecture capabilities are saved in an architecure
specific extension of the header (ckpt_hdr_head_arch); Currently this
includes only FPU capabilities.

Currently only x86-32 is supported.

TODO: validate input values for regs, debug regs, and TLS on restart.

Changelog[v16]:
- All objects are preceded by ckpt_hdr (TLS and xstate_buf)
- Add architecture identifier to main header

Changelog[v14]:
- Use new interface ckpt_hdr_get/put()
- Embed struct ckpt_hdr in struct ckpt_hdr...
- Remove preempt_disable/enable() around init_fpu() and fix leak
- Revert change to pr_debug(), back to ckpt_debug()
- Move code related to task_struct to checkpoint/process.c

Changelog[v12]:
- A couple of missed calls to ckpt_hbuf_put()
- Replace obsolete ckpt_debug() with pr_debug()

Changelog[v9]:
- Add arch-specific header that details architecture capabilities;
split FPU restore to send capabilities only once.
- Test for zero TLS entries in ckpt_write_thread()
- Fix asm/checkpoint_hdr.h so it can be included from user-space

Changelog[v7]:
- Fix save/restore state of FPU

Changelog[v5]:
- Remove preempt_disable() when restoring debug registers

Changelog[v4]:
- Fix header structure alignment

Changelog[v2]:
- Pad header structures to 64 bits to ensure compatibility
- Follow Dave Hansen's refactoring of the original post

Signed-off-by: Oren Laadan <orenl@cs.columbia.edu>
---
arch/x86/include/asm/checkpoint_hdr.h | 110 +++++++++
arch/x86/mm/Makefile | 2 +
arch/x86/mm/checkpoint.c | 431 +++++++++++++++++++++++++++++++++
checkpoint/checkpoint.c | 7 +-
checkpoint/process.c | 20 ++-
checkpoint/restart.c | 6 +
include/linux/checkpoint.h | 10 +
include/linux/checkpoint_hdr.h | 12 +-
8 files changed, 594 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/checkpoint_hdr.h b/arch/x86/include/asm/checkpoint_hdr.h
new file mode 100644
index 0000000..362b499
--- /dev/null
+++ b/arch/x86/include/asm/checkpoint_hdr.h
@@ -0,0 +1,110 @@
+#ifndef __ASM_X86_CKPT_HDR_H
+#define __ASM_X86_CKPT_HDR_H
+/*
+ * Checkpoint/restart - architecture specific headers x86
+ *
+ * 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/checkpoint_hdr.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."
+ */
+
+/* i387 structure seen from kernel/userspace */
+#ifdef __KERNEL__
+#include <asm/processor.h>
+#else
+#include <sys/user.h>
+#endif
+
+#ifndef CONFIG_X86_64
+#define CKPT_ARCH_ID CKPT_ARCH_X86_32
+#endif
+
+/* arch dependent header types */
+enum {
+ CKPT_HDR_THREAD_TLS = 201,
+ CKPT_HDR_CPU_FPU,
+};
+
+struct ckpt_hdr_header_arch {
+ struct ckpt_hdr h;
+ /* FIXME: add HAVE_HWFP */
+ __u16 has_fxsr;
+ __u16 has_xsave;
+ __u16 xstate_size;
+ __u16 _pading;
+} __attribute__((aligned(8)));
+
+struct ckpt_hdr_thread {
+ struct ckpt_hdr h;
+ /* FIXME: restart blocks */
+ __u16 gdt_entry_tls_entries;
+ __u16 sizeof_tls_array;
+ __u16 ntls; /* number of TLS entries to follow */
+} __attribute__((aligned(8)));
+
+struct ckpt_hdr_cpu {
+ struct ckpt_hdr h;
+ /* see struct pt_regs (x86-64) */
+ __u64 r15;
+ __u64 r14;
+ __u64 r13;
+ __u64 r12;
+ __u64 bp;
+ __u64 bx;
+ __u64 r11;
+ __u64 r10;
+ __u64 r9;
+ __u64 r8;
+ __u64 ax;
+ __u64 cx;
+ __u64 dx;
+ __u64 si;
+ __u64 di;
+ __u64 orig_ax;
+ __u64 ip;
+ __u64 cs;
+ __u64 flags;
+ __u64 sp;
+ __u64 ss;
+
+ /* segment registers */
+ __u64 ds;
+ __u64 es;
+ __u64 fs;
+ __u64 gs;
+
+ /* debug registers */
+ __u64 debugreg0;
+ __u64 debugreg1;
+ __u64 debugreg2;
+ __u64 debugreg3;
+ __u64 debugreg6;
+ __u64 debugreg7;
+
+ __u32 uses_debug;
+ __u32 used_math;
+
+ /* thread_xstate contents follow (if used_math) */
+} __attribute__((aligned(8)));
+
+#endif /* __ASM_X86_CKPT_HDR__H */
diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile
index fdd30d0..7d894a5 100644
--- a/arch/x86/mm/Makefile
+++ b/arch/x86/mm/Makefile
@@ -19,3 +19,5 @@ obj-$(CONFIG_K8_NUMA) += k8topology_64.o
obj-$(CONFIG_ACPI_NUMA) += srat_$(BITS).o

obj-$(CONFIG_MEMTEST) += memtest.o
+
+obj-$(CONFIG_CHECKPOINT) += checkpoint.o
diff --git a/arch/x86/mm/checkpoint.c b/arch/x86/mm/checkpoint.c
new file mode 100644
index 0000000..f54fe80
--- /dev/null
+++ b/arch/x86/mm/checkpoint.c
@@ -0,0 +1,431 @@
+/*
+ * Checkpoint/restart - architecture specific support for x86
+ *
+ * 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 <asm/desc.h>
+#include <asm/i387.h>
+
+#include <asm/checkpoint_hdr.h>
+#include <linux/checkpoint.h>
+
+/**************************************************************************
+ * Checkpoint
+ */
+
+/* dump the thread_struct of a given task */
+int checkpoint_thread(struct ckpt_ctx *ctx, struct task_struct *t)
+{
+ struct ckpt_hdr_thread *h;
+ struct thread_struct *thread;
+ struct desc_struct *desc;
+ int ntls = 0;
+ int n, ret;
+
+ h = ckpt_hdr_get_type(ctx, sizeof(*h), CKPT_HDR_THREAD);
+ if (!h)
+ return -ENOMEM;
+
+ thread = &t->thread;
+
+ /* calculate no. of TLS entries that follow */
+ desc = thread->tls_array;
+ for (n = GDT_ENTRY_TLS_ENTRIES; n > 0; n--, desc++) {
+ if (desc->a || desc->b)
+ ntls++;
+ }
+
+ h->gdt_entry_tls_entries = GDT_ENTRY_TLS_ENTRIES;
+ h->sizeof_tls_array = sizeof(thread->tls_array);
+ h->ntls = ntls;
+
+ ret = ckpt_write_obj(ctx, &h->h);
+ ckpt_hdr_put(ctx, h);
+ if (ret < 0)
+ return ret;
+
+ ckpt_debug("ntls %d\n", ntls);
+ if (ntls == 0)
+ return 0;
+
+ /*
+ * For simplicity dump the entire array, cherry-pick upon restart
+ * FIXME: the TLS descriptors in the GDT should be called out and
+ * not tied to the in-kernel representation.
+ */
+ ret = ckpt_write_obj_type(ctx, thread->tls_array,
+ sizeof(thread->tls_array),
+ CKPT_HDR_THREAD_TLS);
+
+ /* IGNORE RESTART BLOCKS FOR NOW ... */
+
+ return ret;
+}
+
+#ifndef CONFIG_X86_64
+
+static void save_cpu_regs(struct ckpt_hdr_cpu *h, struct task_struct *t)
+{
+ struct thread_struct *thread = &t->thread;
+ struct pt_regs *regs = task_pt_regs(t);
+
+ h->bp = regs->bp;
+ h->bx = regs->bx;
+ h->ax = regs->ax;
+ h->cx = regs->cx;
+ h->dx = regs->dx;
+ h->si = regs->si;
+ h->di = regs->di;
+ h->orig_ax = regs->orig_ax;
+ h->ip = regs->ip;
+ h->cs = regs->cs;
+ h->flags = regs->flags;
+ h->sp = regs->sp;
+ h->ss = regs->ss;
+
+ h->ds = regs->ds;
+ h->es = regs->es;
+
+ /*
+ * for checkpoint in process context (from within a container)
+ * the GS and FS registers should be saved from the hardware;
+ * otherwise they are already sabed on the thread structure
+ */
+ if (t == current) {
+ savesegment(gs, h->gs);
+ savesegment(fs, h->fs);
+ } else {
+ h->gs = thread->gs;
+ h->fs = thread->fs;
+ }
+
+ /*
+ * for checkpoint in process context (from within a container),
+ * the actual syscall is taking place at this very moment; so
+ * we (optimistically) subtitute the future return value (0) of
+ * this syscall into the orig_eax, so that upon restart it will
+ * succeed (or it will endlessly retry checkpoint...)
+ */
+ if (t == current) {
+ BUG_ON(h->orig_ax < 0);
+ h->ax = 0;
+ }
+}
+
+static void save_cpu_debug(struct ckpt_hdr_cpu *h, struct task_struct *t)
+{
+ struct thread_struct *thread = &t->thread;
+
+ /* debug regs */
+
+ /*
+ * for checkpoint in process context (from within a container),
+ * get the actual registers; otherwise get the saved values.
+ */
+
+ if (t == current) {
+ get_debugreg(h->debugreg0, 0);
+ get_debugreg(h->debugreg1, 1);
+ get_debugreg(h->debugreg2, 2);
+ get_debugreg(h->debugreg3, 3);
+ get_debugreg(h->debugreg6, 6);
+ get_debugreg(h->debugreg7, 7);
+ } else {
+ h->debugreg0 = thread->debugreg0;
+ h->debugreg1 = thread->debugreg1;
+ h->debugreg2 = thread->debugreg2;
+ h->debugreg3 = thread->debugreg3;
+ h->debugreg6 = thread->debugreg6;
+ h->debugreg7 = thread->debugreg7;
+ }
+
+ h->uses_debug = !!(task_thread_info(t)->flags & TIF_DEBUG);
+}
+
+static void save_cpu_fpu(struct ckpt_hdr_cpu *h, struct task_struct *t)
+{
+ h->used_math = tsk_used_math(t) ? 1 : 0;
+}
+
+static int checkpoint_cpu_fpu(struct ckpt_ctx *ctx, struct task_struct *t)
+{
+ struct ckpt_hdr *h;
+ int ret;
+
+ h = ckpt_hdr_get_type(ctx, xstate_size + sizeof(*h),
+ CKPT_HDR_CPU_FPU);
+ if (!h)
+ return -ENOMEM;
+
+ /* i387 + MMU + SSE logic */
+ preempt_disable(); /* needed it (t == current) */
+
+ /*
+ * normally, no need to unlazy_fpu(), since TS_USEDFPU flag
+ * was cleared when task was context-switched out...
+ * except if we are in process context, in which case we do
+ */
+ if (t == current && (task_thread_info(t)->status & TS_USEDFPU))
+ unlazy_fpu(current);
+
+ /*
+ * For simplicity dump the entire structure.
+ * FIX: need to be deliberate about what registers we are
+ * dumping for traceability and compatibility.
+ */
+ memcpy(h + 1, t->thread.xstate, xstate_size);
+ preempt_enable(); /* needed if (t == current) */
+
+ ret = ckpt_write_obj(ctx, h);
+ ckpt_hdr_put(ctx, h);
+
+ return ret;
+}
+
+#endif /* !CONFIG_X86_64 */
+
+/* dump the cpu state and registers of a given task */
+int checkpoint_cpu(struct ckpt_ctx *ctx, struct task_struct *t)
+{
+ struct ckpt_hdr_cpu *h;
+ int ret;
+
+ h = ckpt_hdr_get_type(ctx, sizeof(*h), CKPT_HDR_CPU);
+ if (!h)
+ return -ENOMEM;
+
+ save_cpu_regs(h, t);
+ save_cpu_debug(h, t);
+ save_cpu_fpu(h, t);
+
+ ckpt_debug("math %d debug %d\n", h->used_math, h->uses_debug);
+
+ ret = ckpt_write_obj(ctx, &h->h);
+ if (ret < 0)
+ goto out;
+
+ if (h->used_math)
+ ret = checkpoint_cpu_fpu(ctx, t);
+ out:
+ ckpt_hdr_put(ctx, h);
+ return ret;
+}
+
+int checkpoint_write_header_arch(struct ckpt_ctx *ctx)
+{
+ struct ckpt_hdr_header_arch *h;
+ int ret;
+
+ h = ckpt_hdr_get_type(ctx, sizeof(*h), CKPT_HDR_HEADER_ARCH);
+ if (!h)
+ return -ENOMEM;
+
+ /* FPU capabilities */
+ h->has_fxsr = cpu_has_fxsr;
+ h->has_xsave = cpu_has_xsave;
+ h->xstate_size = xstate_size;
+
+ ret = ckpt_write_obj(ctx, &h->h);
+ ckpt_hdr_put(ctx, h);
+
+ return ret;
+}
+
+/**************************************************************************
+ * Restart
+ */
+
+/* read the thread_struct into the current task */
+int restore_thread(struct ckpt_ctx *ctx)
+{
+ struct ckpt_hdr_thread *h;
+ struct task_struct *t = current;
+ struct thread_struct *thread = &t->thread;
+ int ret;
+
+ h = ckpt_read_obj_type(ctx, sizeof(*h), CKPT_HDR_THREAD);
+ if (IS_ERR(h))
+ return PTR_ERR(h);
+
+ ckpt_debug("ntls %d\n", h->ntls);
+
+ ret = -EINVAL;
+ if (h->gdt_entry_tls_entries != GDT_ENTRY_TLS_ENTRIES ||
+ h->sizeof_tls_array != sizeof(thread->tls_array) ||
+ h->ntls > GDT_ENTRY_TLS_ENTRIES)
+ goto out;
+
+ if (h->ntls > 0) {
+ struct ckpt_hdr *hh;
+ int size, cpu;
+
+ /*
+ * restore TLS by hand: why convert to struct user_desc if
+ * sys_set_thread_entry() will convert it back ?
+ */
+
+ size = sizeof(struct desc_struct) * GDT_ENTRY_TLS_ENTRIES;
+ hh = ckpt_read_obj_type(ctx, size + sizeof(*hh),
+ CKPT_HDR_THREAD_TLS);
+ if (IS_ERR(hh)) {
+ ret = PTR_ERR(hh);
+ goto out;
+ }
+
+ /* TODO: ADD SANITY CHECKS TO VERIFY VALIDITY OF VALUES */
+ cpu = get_cpu();
+ memcpy(thread->tls_array, hh + 1, size);
+ load_TLS(thread, cpu);
+ put_cpu();
+
+ ckpt_hdr_put(ctx, hh);
+ }
+
+ ret = 0;
+ out:
+ ckpt_hdr_put(ctx, h);
+ return ret;
+}
+
+#ifndef CONFIG_X86_64
+
+static int load_cpu_regs(struct ckpt_hdr_cpu *h, struct task_struct *t)
+{
+ struct thread_struct *thread = &t->thread;
+ struct pt_regs *regs = task_pt_regs(t);
+
+ /* TODO: ADD SANITY CHECKS TO VERIFY VALIDITY OF VALUES */
+ regs->bx = h->bx;
+ regs->cx = h->cx;
+ regs->dx = h->dx;
+ regs->si = h->si;
+ regs->di = h->di;
+ regs->bp = h->bp;
+ regs->ax = h->ax;
+ regs->ds = h->ds;
+ regs->es = h->es;
+ regs->orig_ax = h->orig_ax;
+ regs->ip = h->ip;
+ regs->cs = h->cs;
+ regs->flags = h->flags;
+ regs->sp = h->sp;
+ regs->ss = h->ss;
+
+ thread->gs = h->gs;
+ thread->fs = h->fs;
+ loadsegment(gs, h->gs);
+ loadsegment(fs, h->fs);
+
+ return 0;
+}
+
+static int load_cpu_debug(struct ckpt_hdr_cpu *h, struct task_struct *t)
+{
+ /* TODO: ADD SANITY CHECKS TO VERIFY VALIDITY OF VALUES */
+ if (h->uses_debug) {
+ set_debugreg(h->debugreg0, 0);
+ set_debugreg(h->debugreg1, 1);
+ /* ignore 4, 5 */
+ set_debugreg(h->debugreg2, 2);
+ set_debugreg(h->debugreg3, 3);
+ set_debugreg(h->debugreg6, 6);
+ set_debugreg(h->debugreg7, 7);
+ }
+
+ return 0;
+}
+
+static int load_cpu_fpu(struct ckpt_hdr_cpu *h, struct task_struct *t)
+{
+ preempt_disable();
+
+ __clear_fpu(t); /* in case we used FPU in user mode */
+
+ if (!h->used_math)
+ clear_used_math();
+
+ preempt_enable();
+ return 0;
+}
+
+static int restore_cpu_fpu(struct ckpt_ctx *ctx, struct task_struct *t)
+{
+ struct ckpt_hdr *h;
+ int ret;
+
+ /* init_fpu() eventually also calls set_used_math() */
+ ret = init_fpu(current);
+ if (ret < 0)
+ return ret;
+
+ h = ckpt_read_obj_type(ctx, xstate_size + sizeof(*h),
+ CKPT_HDR_CPU_FPU);
+ if (IS_ERR(h))
+ return PTR_ERR(h);
+
+ memcpy(t->thread.xstate, h + 1, xstate_size);
+
+ ckpt_hdr_put(ctx, h);
+ return ret;
+}
+
+#endif /* !CONFIG_X86_64 */
+
+/* read the cpu state and registers for the current task */
+int restore_cpu(struct ckpt_ctx *ctx)
+{
+ struct ckpt_hdr_cpu *h;
+ struct task_struct *t = current;
+ int ret;
+
+ h = ckpt_read_obj_type(ctx, sizeof(*h), CKPT_HDR_CPU);
+ if (IS_ERR(h))
+ return PTR_ERR(h);
+
+ ckpt_debug("math %d debug %d\n", h->used_math, h->uses_debug);
+
+ ret = load_cpu_regs(h, t);
+ if (ret < 0)
+ goto out;
+ ret = load_cpu_debug(h, t);
+ if (ret < 0)
+ goto out;
+ ret = load_cpu_fpu(h, t);
+ if (ret < 0)
+ goto out;
+
+ if (h->used_math)
+ ret = restore_cpu_fpu(ctx, t);
+ out:
+ ckpt_hdr_put(ctx, h);
+ return ret;
+}
+
+int restore_read_header_arch(struct ckpt_ctx *ctx)
+{
+ struct ckpt_hdr_header_arch *h;
+ int ret = 0;
+
+ h = ckpt_read_obj_type(ctx, sizeof(*h), CKPT_HDR_HEADER_ARCH);
+ if (IS_ERR(h))
+ return PTR_ERR(h);
+
+ /* FIX: verify compatibility of architecture features */
+
+ /* verify FPU capabilities */
+ if (h->has_fxsr != cpu_has_fxsr ||
+ h->has_xsave != cpu_has_xsave ||
+ h->xstate_size != xstate_size)
+ ret = -EINVAL;
+
+ ckpt_hdr_put(ctx, h);
+ return ret;
+}
diff --git a/checkpoint/checkpoint.c b/checkpoint/checkpoint.c
index 56b690a..409c78b 100644
--- a/checkpoint/checkpoint.c
+++ b/checkpoint/checkpoint.c
@@ -190,6 +190,8 @@ static int checkpoint_write_header(struct ckpt_ctx *ctx)
do_gettimeofday(&ktv);
uts = utsname();

+ h->arch_id = cpu_to_le16(CKPT_ARCH_ID); /* see asm/checkpoitn.h */
+
h->magic = CHECKPOINT_MAGIC_HEAD;
h->major = (LINUX_VERSION_CODE >> 16) & 0xff;
h->minor = (LINUX_VERSION_CODE >> 8) & 0xff;
@@ -219,7 +221,10 @@ static int checkpoint_write_header(struct ckpt_ctx *ctx)
ret = ckpt_write_buffer(ctx, uts->machine, sizeof(uts->machine));
up:
up_read(&uts_sem);
- return ret;
+ if (ret < 0)
+ return ret;
+
+ return checkpoint_write_header_arch(ctx);
}

/* write the checkpoint trailer */
diff --git a/checkpoint/process.c b/checkpoint/process.c
index c2b7564..6cab717 100644
--- a/checkpoint/process.c
+++ b/checkpoint/process.c
@@ -53,7 +53,15 @@ int checkpoint_task(struct ckpt_ctx *ctx, struct task_struct *t)

ret = checkpoint_task_struct(ctx, t);
ckpt_debug("task %d\n", ret);
-
+ if (ret < 0)
+ goto out;
+ ret = checkpoint_thread(ctx, t);
+ ckpt_debug("thread %d\n", ret);
+ if (ret < 0)
+ goto out;
+ ret = checkpoint_cpu(ctx, t);
+ ckpt_debug("cpu %d\n", ret);
+ out:
return ret;
}

@@ -92,6 +100,14 @@ int restore_task(struct ckpt_ctx *ctx)

ret = restore_task_struct(ctx);
ckpt_debug("task %d\n", ret);
-
+ if (ret < 0)
+ goto out;
+ ret = restore_thread(ctx);
+ ckpt_debug("thread %d\n", ret);
+ if (ret < 0)
+ goto out;
+ ret = restore_cpu(ctx);
+ ckpt_debug("cpu %d\n", ret);
+ out:
return ret;
}
diff --git a/checkpoint/restart.c b/checkpoint/restart.c
index a6f73d3..e839538 100644
--- a/checkpoint/restart.c
+++ b/checkpoint/restart.c
@@ -248,6 +248,8 @@ static int restore_read_header(struct ckpt_ctx *ctx)
return PTR_ERR(h);

ret = -EINVAL;
+ if (le16_to_cpu(h->arch_id) != CKPT_ARCH_ID)
+ goto out;
if (h->magic != CHECKPOINT_MAGIC_HEAD ||
h->rev != CHECKPOINT_VERSION ||
h->major != ((LINUX_VERSION_CODE >> 16) & 0xff) ||
@@ -276,6 +278,10 @@ static int restore_read_header(struct ckpt_ctx *ctx)
if (ret < 0)
goto out;
ret = _ckpt_read_buffer(ctx, uts->machine, sizeof(uts->machine));
+ if (ret < 0)
+ goto out;
+
+ ret = restore_read_header_arch(ctx);
out:
kfree(uts);
ckpt_hdr_put(ctx, h);
diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
index 14da928..6247114 100644
--- a/include/linux/checkpoint.h
+++ b/include/linux/checkpoint.h
@@ -12,6 +12,7 @@

#include <linux/checkpoint_types.h>
#include <linux/checkpoint_hdr.h>
+#include <asm/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);
@@ -43,6 +44,15 @@ extern int do_restart(struct ckpt_ctx *ctx, pid_t pid);
extern int checkpoint_task(struct ckpt_ctx *ctx, struct task_struct *t);
extern int restore_task(struct ckpt_ctx *ctx);

+/* arch hooks */
+extern int checkpoint_write_header_arch(struct ckpt_ctx *ctx);
+extern int checkpoint_thread(struct ckpt_ctx *ctx, struct task_struct *t);
+extern int checkpoint_cpu(struct ckpt_ctx *ctx, struct task_struct *t);
+
+extern int restore_read_header_arch(struct ckpt_ctx *ctx);
+extern int restore_thread(struct ckpt_ctx *ctx);
+extern int restore_cpu(struct ckpt_ctx *ctx);
+

/* debugging flags */
#define CKPT_DBASE 0x1 /* anything */
diff --git a/include/linux/checkpoint_hdr.h b/include/linux/checkpoint_hdr.h
index c9a1653..a0c576c 100644
--- a/include/linux/checkpoint_hdr.h
+++ b/include/linux/checkpoint_hdr.h
@@ -41,22 +41,32 @@ struct ckpt_hdr {
/* header types */
enum {
CKPT_HDR_HEADER = 1,
+ CKPT_HDR_HEADER_ARCH,
CKPT_HDR_BUFFER,
CKPT_HDR_STRING,

CKPT_HDR_TASK = 101,
+ CKPT_HDR_THREAD,
+ CKPT_HDR_CPU,
+
+ /* 201-299: reserved for arch-dependent */

CKPT_HDR_TAIL = 9001,

CKPT_HDR_ERROR = 9999,
};

+/* architecture */
+enum {
+ CKPT_ARCH_X86_32 = 1,
+};
+
/* checkpoint image header */
struct ckpt_hdr_header {
struct ckpt_hdr h;
__u64 magic;

- __u16 _padding;
+ __u16 arch_id;

__u16 major;
__u16 minor;
--
1.6.0.4


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