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Subject[RFC v17][PATCH 55/60] c/r: define s390-specific checkpoint-restart code
Date
From: Dan Smith <danms@us.ibm.com>

Implement the s390 arch-specific checkpoint/restart helpers. This
is on top of Oren Laadan's c/r code.

With these, I am able to checkpoint and restart simple programs as per
Oren's patch intro. While on x86 I never had to freeze a single task
to checkpoint it, on s390 I do need to. That is a prereq for consistent
snapshots (esp with multiple processes) anyway so I don't see that as
a problem.

Changelog:
Jun 15:
. Fix checkpoint and restart compat wrappers
May 28:
. Export asm/checkpoint_hdr.h to userspace
. Define CKPT_ARCH_ID for S390
Apr 11:
. Introduce ckpt_arch_vdso()
Feb 27:
. Add checkpoint_s390.h
. Fixed up save and restore of PSW, with the non-address bits
properly masked out
Feb 25:
. Make checkpoint_hdr.h safe for inclusion in userspace
. Replace comment about vsdo code
. Add comment about restoring access registers
. Write and read an empty ckpt_hdr_head_arch record to appease
code (mktree) that expects it to be there
. Utilize NUM_CKPT_WORDS in checkpoint_hdr.h
Feb 24:
. Use CKPT_COPY() to unify the un/loading of cpu and mm state
. Fix fprs definition in ckpt_hdr_cpu
. Remove debug WARN_ON() from checkpoint.c
Feb 23:
. Macro-ize the un/packing of trace flags
. Fix the crash when externally-linked
. Break out the restart functions into restart.c
. Remove unneeded s390_enable_sie() call
Jan 30:
. Switched types in ckpt_hdr_cpu to __u64 etc.
(Per Oren suggestion)
. Replaced direct inclusion of structs in
ckpt_hdr_cpu with the struct members.
(Per Oren suggestion)
. Also ended up adding a bunch of new things
into restart (mm_segment, ksp, etc) in vain
attempt to get code using fpu to not segfault
after restart.

Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Signed-off-by: Dan Smith <danms@us.ibm.com>
---
arch/s390/include/asm/Kbuild | 1 +
arch/s390/include/asm/checkpoint_hdr.h | 89 +++++++++++++++
arch/s390/include/asm/unistd.h | 4 +-
arch/s390/kernel/compat_wrapper.S | 14 +++
arch/s390/kernel/syscalls.S | 2 +
arch/s390/mm/Makefile | 1 +
arch/s390/mm/checkpoint.c | 183 ++++++++++++++++++++++++++++++++
arch/s390/mm/checkpoint_s390.h | 23 ++++
include/linux/checkpoint_hdr.h | 2 +
9 files changed, 318 insertions(+), 1 deletions(-)
create mode 100644 arch/s390/include/asm/checkpoint_hdr.h
create mode 100644 arch/s390/mm/checkpoint.c
create mode 100644 arch/s390/mm/checkpoint_s390.h
diff --git a/arch/s390/include/asm/Kbuild b/arch/s390/include/asm/Kbuild
index 63a2341..3282a6e 100644
--- a/arch/s390/include/asm/Kbuild
+++ b/arch/s390/include/asm/Kbuild
@@ -8,6 +8,7 @@ header-y += ucontext.h
header-y += vtoc.h
header-y += zcrypt.h
header-y += chsc.h
+header-y += checkpoint_hdr.h

unifdef-y += cmb.h
unifdef-y += debug.h
diff --git a/arch/s390/include/asm/checkpoint_hdr.h b/arch/s390/include/asm/checkpoint_hdr.h
new file mode 100644
index 0000000..ad9449e
--- /dev/null
+++ b/arch/s390/include/asm/checkpoint_hdr.h
@@ -0,0 +1,89 @@
+#ifndef __ASM_S390_CKPT_HDR_H
+#define __ASM_S390_CKPT_HDR_H
+/*
+ * Checkpoint/restart - architecture specific headers s/390
+ *
+ * Copyright IBM Corp. 2009
+ *
+ * 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.
+ */
+
+#ifndef _CHECKPOINT_CKPT_HDR_H_
+#error asm/checkpoint_hdr.h included directly
+#endif
+
+#include <linux/types.h>
+#include <asm/ptrace.h>
+
+#ifdef __KERNEL__
+#include <asm/processor.h>
+#else
+#include <sys/user.h>
+#endif
+
+#ifdef CONFIG_64BIT
+#define CKPT_ARCH_ID CKPT_ARCH_S390X
+/* else - if we ever support 32bit - CKPT_ARCH_S390 */
+#endif
+
+/*
+ * Notes
+ * NUM_GPRS defined in <asm/ptrace.h> to be 16
+ * NUM_FPRS defined in <asm/ptrace.h> to be 16
+ * NUM_APRS defined in <asm/ptrace.h> to be 16
+ * NUM_CR_WORDS defined in <asm/ptrace.h> to be 3
+ */
+struct ckpt_hdr_cpu {
+ struct ckpt_hdr h;
+ __u64 args[1];
+ __u64 gprs[NUM_GPRS];
+ __u64 orig_gpr2;
+ __u16 svcnr;
+ __u16 ilc;
+ __u32 acrs[NUM_ACRS];
+ __u64 ieee_instruction_pointer;
+
+ /* psw_t */
+ __u64 psw_t_mask;
+ __u64 psw_t_addr;
+
+ /* s390_fp_regs_t */
+ __u32 fpc;
+ union {
+ float f;
+ double d;
+ __u64 ui;
+ struct {
+ __u32 fp_hi;
+ __u32 fp_lo;
+ } fp;
+ } fprs[NUM_FPRS];
+
+ /* per_struct */
+ __u64 per_control_regs[NUM_CR_WORDS];
+ __u64 starting_addr;
+ __u64 ending_addr;
+ __u64 address;
+ __u16 perc_atmid;
+ __u8 access_id;
+ __u8 single_step;
+ __u8 instruction_fetch;
+};
+
+struct ckpt_hdr_mm_context {
+ struct ckpt_hdr h;
+ unsigned long vdso_base;
+ int noexec;
+ int has_pgste;
+ int alloc_pgste;
+ unsigned long asce_bits;
+ unsigned long asce_limit;
+};
+
+struct ckpt_hdr_header_arch {
+ struct ckpt_hdr h;
+};
+
+#endif /* __ASM_S390_CKPT_HDR__H */
diff --git a/arch/s390/include/asm/unistd.h b/arch/s390/include/asm/unistd.h
index c80602d..5d1678a 100644
--- a/arch/s390/include/asm/unistd.h
+++ b/arch/s390/include/asm/unistd.h
@@ -269,7 +269,9 @@
#define __NR_pwritev 329
#define __NR_rt_tgsigqueueinfo 330
#define __NR_perf_counter_open 331
-#define NR_syscalls 332
+#define __NR_checkpoint 332
+#define __NR_restart 333
+#define NR_syscalls 334

/*
* There are some system calls that are not present on 64 bit, some
diff --git a/arch/s390/kernel/compat_wrapper.S b/arch/s390/kernel/compat_wrapper.S
index 88a8336..e882f99 100644
--- a/arch/s390/kernel/compat_wrapper.S
+++ b/arch/s390/kernel/compat_wrapper.S
@@ -1840,3 +1840,17 @@ sys_perf_counter_open_wrapper:
lgfr %r5,%r5 # int
llgfr %r6,%r6 # unsigned long
jg sys_perf_counter_open # branch to system call
+
+ .globl sys_checkpoint_wrapper
+sys_checkpoint_wrapper:
+ lgfr %r2,%r2 # pid_t
+ lgfr %r3,%r3 # int
+ llgfr %r4,%r4 # unsigned long
+ jg compat_sys_checkpoint
+
+ .globl sys_restore_wrapper
+sys_restore_wrapper:
+ lgfr %r2,%r2 # int
+ lgfr %r3,%r3 # int
+ llgfr %r4,%r4 # unsigned long
+ jg compat_sys_restore
diff --git a/arch/s390/kernel/syscalls.S b/arch/s390/kernel/syscalls.S
index ad1acd2..67518e2 100644
--- a/arch/s390/kernel/syscalls.S
+++ b/arch/s390/kernel/syscalls.S
@@ -340,3 +340,5 @@ SYSCALL(sys_preadv,sys_preadv,compat_sys_preadv_wrapper)
SYSCALL(sys_pwritev,sys_pwritev,compat_sys_pwritev_wrapper)
SYSCALL(sys_rt_tgsigqueueinfo,sys_rt_tgsigqueueinfo,compat_sys_rt_tgsigqueueinfo_wrapper) /* 330 */
SYSCALL(sys_perf_counter_open,sys_perf_counter_open,sys_perf_counter_open_wrapper)
+SYSCALL(sys_checkpoint,sys_checkpoint,sys_checkpoint_wrapper)
+SYSCALL(sys_restart,sys_restart,sys_restore_wrapper)
diff --git a/arch/s390/mm/Makefile b/arch/s390/mm/Makefile
index db05661..e3d356d 100644
--- a/arch/s390/mm/Makefile
+++ b/arch/s390/mm/Makefile
@@ -6,3 +6,4 @@ obj-y := init.o fault.o extmem.o mmap.o vmem.o pgtable.o maccess.o
obj-$(CONFIG_CMM) += cmm.o
obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
obj-$(CONFIG_PAGE_STATES) += page-states.o
+obj-$(CONFIG_CHECKPOINT) += checkpoint.o
diff --git a/arch/s390/mm/checkpoint.c b/arch/s390/mm/checkpoint.c
new file mode 100644
index 0000000..a4a5da9
--- /dev/null
+++ b/arch/s390/mm/checkpoint.c
@@ -0,0 +1,183 @@
+/*
+ * Checkpoint/restart - architecture specific support for s390
+ *
+ * Copyright IBM Corp. 2009
+ *
+ * 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/kernel.h>
+#include <asm/system.h>
+#include <asm/pgtable.h>
+#include <asm/elf.h>
+
+#include <linux/checkpoint.h>
+#include <linux/checkpoint_hdr.h>
+
+/**************************************************************************
+ * Checkpoint
+ */
+
+static void s390_copy_regs(int op, struct ckpt_hdr_cpu *h,
+ struct task_struct *t)
+{
+ struct pt_regs *regs = task_pt_regs(t);
+ struct thread_struct *thr = &t->thread;
+
+ /* Save the whole PSW to facilitate forensic debugging, but only
+ * restore the address portion to avoid letting userspace do
+ * bad things by manipulating its value.
+ */
+ if (op == CKPT_CPT) {
+ CKPT_COPY(op, h->psw_t_addr, regs->psw.addr);
+ } else {
+ regs->psw.addr &= ~PSW_ADDR_INSN;
+ regs->psw.addr |= h->psw_t_addr;
+ }
+
+ CKPT_COPY(op, h->args[0], regs->args[0]);
+ CKPT_COPY(op, h->orig_gpr2, regs->orig_gpr2);
+ CKPT_COPY(op, h->svcnr, regs->svcnr);
+ CKPT_COPY(op, h->ilc, regs->ilc);
+ CKPT_COPY(op, h->ieee_instruction_pointer,
+ thr->ieee_instruction_pointer);
+ CKPT_COPY(op, h->psw_t_mask, regs->psw.mask);
+ CKPT_COPY(op, h->fpc, thr->fp_regs.fpc);
+ CKPT_COPY(op, h->starting_addr, thr->per_info.starting_addr);
+ CKPT_COPY(op, h->ending_addr, thr->per_info.ending_addr);
+ CKPT_COPY(op, h->address, thr->per_info.lowcore.words.address);
+ CKPT_COPY(op, h->perc_atmid, thr->per_info.lowcore.words.perc_atmid);
+ CKPT_COPY(op, h->access_id, thr->per_info.lowcore.words.access_id);
+ CKPT_COPY(op, h->single_step, thr->per_info.single_step);
+ CKPT_COPY(op, h->instruction_fetch, thr->per_info.instruction_fetch);
+
+ CKPT_COPY_ARRAY(op, h->gprs, regs->gprs, NUM_GPRS);
+ CKPT_COPY_ARRAY(op, h->fprs, thr->fp_regs.fprs, NUM_FPRS);
+ CKPT_COPY_ARRAY(op, h->acrs, thr->acrs, NUM_ACRS);
+ CKPT_COPY_ARRAY(op, h->per_control_regs,
+ thr->per_info.control_regs.words.cr, NUM_CR_WORDS);
+}
+
+static void s390_mm(int op, struct ckpt_hdr_mm_context *h,
+ struct mm_struct *mm)
+{
+ CKPT_COPY(op, h->noexec, mm->context.noexec);
+ CKPT_COPY(op, h->has_pgste, mm->context.has_pgste);
+ CKPT_COPY(op, h->alloc_pgste, mm->context.alloc_pgste);
+ CKPT_COPY(op, h->asce_bits, mm->context.asce_bits);
+ CKPT_COPY(op, h->asce_limit, mm->context.asce_limit);
+}
+
+int checkpoint_thread(struct ckpt_ctx *ctx, struct task_struct *t)
+{
+ return 0;
+}
+
+/* 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;
+
+ s390_copy_regs(CKPT_CPT, h, t);
+
+ ret = ckpt_write_obj(ctx, (struct ckpt_hdr *) h);
+ ckpt_hdr_put(ctx, h);
+
+ return ret;
+}
+
+/* Write an empty header since it is assumed to be there */
+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;
+
+ ret = ckpt_write_obj(ctx, (struct ckpt_hdr *) h);
+ ckpt_hdr_put(ctx, h);
+
+ return ret;
+}
+
+int checkpoint_mm_context(struct ckpt_ctx *ctx, struct mm_struct *mm)
+{
+ struct ckpt_hdr_mm_context *h;
+ int ret;
+
+ h = ckpt_hdr_get_type(ctx, sizeof(*h), CKPT_HDR_MM_CONTEXT);
+ if (!h)
+ return -ENOMEM;
+
+ s390_mm(CKPT_CPT, h, mm);
+
+ ret = ckpt_write_obj(ctx, (struct ckpt_hdr *) h);
+ ckpt_hdr_put(ctx, h);
+
+ return ret;
+}
+
+/**************************************************************************
+ * Restart
+ */
+
+int restore_thread(struct ckpt_ctx *ctx)
+{
+ return 0;
+}
+
+int restore_cpu(struct ckpt_ctx *ctx)
+{
+ struct ckpt_hdr_cpu *h;
+
+ h = ckpt_read_obj_type(ctx, sizeof(*h), CKPT_HDR_CPU);
+ if (IS_ERR(h))
+ return PTR_ERR(h);
+
+ s390_copy_regs(CKPT_RST, h, current);
+
+ /* s390 does not restore the access registers after a syscall,
+ * but does on a task switch. Since we're switching tasks (in
+ * a way), we need to replicate that behavior here.
+ */
+ restore_access_regs(h->acrs);
+
+ ckpt_hdr_put(ctx, h);
+ return 0;
+}
+
+int restore_read_header_arch(struct ckpt_ctx *ctx)
+{
+ struct ckpt_hdr_header_arch *h;
+
+ h = ckpt_read_obj_type(ctx, sizeof(*h), CKPT_HDR_HEADER_ARCH);
+ if (IS_ERR(h))
+ return PTR_ERR(h);
+
+ ckpt_hdr_put(ctx, h);
+ return 0;
+}
+
+
+int restore_mm_context(struct ckpt_ctx *ctx, struct mm_struct *mm)
+{
+ struct ckpt_hdr_mm_context *h;
+
+ h = ckpt_read_obj_type(ctx, sizeof(*h), CKPT_HDR_MM_CONTEXT);
+ if (IS_ERR(h))
+ return PTR_ERR(h);
+
+ s390_mm(CKPT_RST, h, mm);
+
+ ckpt_hdr_put(ctx, h);
+ return 0;
+}
diff --git a/arch/s390/mm/checkpoint_s390.h b/arch/s390/mm/checkpoint_s390.h
new file mode 100644
index 0000000..c3bf24d
--- /dev/null
+++ b/arch/s390/mm/checkpoint_s390.h
@@ -0,0 +1,23 @@
+/*
+ * Checkpoint/restart - architecture specific support for s390
+ *
+ * Copyright IBM Corp. 2009
+ *
+ * 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.
+ */
+
+#ifndef _S390_CHECKPOINT_H
+#define _S390_CHECKPOINT_H
+
+#include <linux/checkpoint_hdr.h>
+#include <linux/sched.h>
+#include <linux/mm_types.h>
+
+extern void checkpoint_s390_regs(int op, struct ckpt_hdr_cpu *h,
+ struct task_struct *t);
+extern void checkpoint_s390_mm(int op, struct ckpt_hdr_mm_context *h,
+ struct mm_struct *mm);
+
+#endif /* _S390_CHECKPOINT_H */
diff --git a/include/linux/checkpoint_hdr.h b/include/linux/checkpoint_hdr.h
index 2364a6f..3671e72 100644
--- a/include/linux/checkpoint_hdr.h
+++ b/include/linux/checkpoint_hdr.h
@@ -87,7 +87,9 @@ enum {

/* architecture */
enum {
+ /* do not change order (will break ABI) */
CKPT_ARCH_X86_32 = 1,
+ CKPT_ARCH_S390X,
};

/* shared objrects (objref) */
--
1.6.0.4


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