[PATCH 3/3] c/r: define s390-specific checkpoint-restart code (v7)

Dan Smith
2009-03-03T15:57:39Z

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:
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 cr_hdr_head_arch record to appease
code (mktree) that expects it to be there
. Utilize NUM_CR_WORDS in checkpoint_hdr.h
Feb 24:
. Use CR_COPY() to unify the un/loading of cpu and mm state
. Fix fprs definition in cr_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 cr_hdr_cpu to __u64 etc.
(Per Oren suggestion)
. Replaced direct inclusion of structs in
cr_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/checkpoint_hdr.h | 88 ++++++++++++++++++++++
arch/s390/include/asm/unistd.h | 4 +-
arch/s390/kernel/compat_wrapper.S | 12 +++
arch/s390/kernel/syscalls.S | 2 +
arch/s390/mm/Makefile | 1 +
arch/s390/mm/checkpoint.c | 125 ++++++++++++++++++++++++++++++++
arch/s390/mm/checkpoint_s390.h | 22 ++++++
arch/s390/mm/restart.c | 81 +++++++++++++++++++++
checkpoint/Kconfig | 2 +-
9 files changed, 335 insertions(+), 2 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
create mode 100644 arch/s390/mm/restart.c

diff --git a/arch/s390/include/asm/checkpoint_hdr.h b/arch/s390/include/asm/checkpoint_hdr.h
new file mode 100644
index 0000000..0a405c2
--- /dev/null
+++ b/arch/s390/include/asm/checkpoint_hdr.h
@@ -0,0 +1,88 @@
+#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.
+ */
+
+#include <linux/types.h>
+#include <asm/ptrace.h>
+
+#ifdef __KERNEL__
+#include <asm/processor.h>
+#else
+#include <sys/user.h>
+#endif
+
+#ifdef __s390x__
+
+/*
+ * 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 cr_hdr_cpu {
+ __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 cr_hdr_mm_context {
+ unsigned long vdso_base;
+ int noexec;
+ int has_pgste;
+ int alloc_pgste;
+ unsigned long asce_bits;
+ unsigned long asce_limit;
+};
+
+struct cr_hdr_head_arch {
+};
+
+#ifdef __KERNEL__
+/* Functions for copying to/from the header structs */
+extern void cr_s390_regs(int op, struct cr_hdr_cpu *hh, struct task_struct *t);
+extern void cr_s390_mm(int op, struct cr_hdr_mm_context *hh,
+ struct mm_struct *mm);
+#endif
+
+#endif /* __s390x__ */
+
+#endif /* __ASM_S390_CKPT_HDR__H */
diff --git a/arch/s390/include/asm/unistd.h b/arch/s390/include/asm/unistd.h
index c8ad350..ffe64a0 100644
--- a/arch/s390/include/asm/unistd.h
+++ b/arch/s390/include/asm/unistd.h
@@ -265,7 +265,9 @@
#define __NR_pipe2 325
#define __NR_dup3 326
#define __NR_epoll_create1 327
-#define NR_syscalls 328
+#define __NR_checkpoint 328
+#define __NR_restart 329
+#define NR_syscalls 330

/*
* 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 fc2c971..9546a81 100644
--- a/arch/s390/kernel/compat_wrapper.S
+++ b/arch/s390/kernel/compat_wrapper.S
@@ -1767,3 +1767,15 @@ sys_dup3_wrapper:
sys_epoll_create1_wrapper:
lgfr %r2,%r2 # int
jg sys_epoll_create1 # 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
+
+ .globl sys_restart_wrapper
+sys_restart_wrapper:
+ lgfr %r2,%r2 # int
+ lgfr %r3,%r3 # int
+ llgfr %r4,%r4 # unsigned long
diff --git a/arch/s390/kernel/syscalls.S b/arch/s390/kernel/syscalls.S
index 2d61787..54316c8 100644
--- a/arch/s390/kernel/syscalls.S
+++ b/arch/s390/kernel/syscalls.S
@@ -336,3 +336,5 @@ SYSCALL(sys_inotify_init1,sys_inotify_init1,sys_inotify_init1_wrapper)
SYSCALL(sys_pipe2,sys_pipe2,sys_pipe2_wrapper) /* 325 */
SYSCALL(sys_dup3,sys_dup3,sys_dup3_wrapper)
SYSCALL(sys_epoll_create1,sys_epoll_create1,sys_epoll_create1_wrapper)
+SYSCALL(sys_checkpoint,sys_checkpoint,sys_checkpoint_wrapper)
+SYSCALL(sys_restart,sys_restart,sys_restart_wrapper)
diff --git a/arch/s390/mm/Makefile b/arch/s390/mm/Makefile
index 2a74581..040fbb7 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
obj-$(CONFIG_CMM) += cmm.o
obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
obj-$(CONFIG_PAGE_STATES) += page-states.o
+obj-$(CONFIG_CHECKPOINT_RESTART) += checkpoint.o restart.o
diff --git a/arch/s390/mm/checkpoint.c b/arch/s390/mm/checkpoint.c
new file mode 100644
index 0000000..113c865
--- /dev/null
+++ b/arch/s390/mm/checkpoint.c
@@ -0,0 +1,125 @@
+/*
+ * 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/checkpoint.h>
+#include <linux/checkpoint_hdr.h>
+#include <linux/kernel.h>
+#include <asm/system.h>
+#include <asm/pgtable.h>
+
+#include "checkpoint_s390.h"
+
+void cr_s390_regs(int op, struct cr_hdr_cpu *hh, 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 == CR_CPT) {
+ CR_COPY(op, hh->psw_t_addr, regs->psw.addr);
+ } else {
+ regs->psw.addr &= ~PSW_ADDR_INSN;
+ regs->psw.addr |= hh->psw_t_addr;
+ }
+
+ CR_COPY(op, hh->args[0], regs->args[0]);
+ CR_COPY(op, hh->orig_gpr2, regs->orig_gpr2);
+ CR_COPY(op, hh->svcnr, regs->svcnr);
+ CR_COPY(op, hh->ilc, regs->ilc);
+ CR_COPY(op, hh->ieee_instruction_pointer,
+ thr->ieee_instruction_pointer);
+ CR_COPY(op, hh->psw_t_mask, regs->psw.mask);
+ CR_COPY(op, hh->fpc, thr->fp_regs.fpc);
+ CR_COPY(op, hh->starting_addr, thr->per_info.starting_addr);
+ CR_COPY(op, hh->ending_addr, thr->per_info.ending_addr);
+ CR_COPY(op, hh->address, thr->per_info.lowcore.words.address);
+ CR_COPY(op, hh->perc_atmid, thr->per_info.lowcore.words.perc_atmid);
+ CR_COPY(op, hh->access_id, thr->per_info.lowcore.words.access_id);
+ CR_COPY(op, hh->single_step, thr->per_info.single_step);
+ CR_COPY(op, hh->instruction_fetch, thr->per_info.instruction_fetch);
+
+ CR_COPY_ARRAY(op, hh->gprs, regs->gprs, NUM_GPRS);
+ CR_COPY_ARRAY(op, hh->fprs, thr->fp_regs.fprs, NUM_FPRS);
+ CR_COPY_ARRAY(op, hh->acrs, thr->acrs, NUM_ACRS);
+ CR_COPY_ARRAY(op, hh->per_control_regs,
+ thr->per_info.control_regs.words.cr, NUM_CR_WORDS);
+
+}
+
+void cr_s390_mm(int op, struct cr_hdr_mm_context *hh, struct mm_struct *mm)
+{
+ CR_COPY(op, hh->noexec, mm->context.noexec);
+ CR_COPY(op, hh->has_pgste, mm->context.has_pgste);
+ CR_COPY(op, hh->alloc_pgste, mm->context.alloc_pgste);
+ CR_COPY(op, hh->asce_bits, mm->context.asce_bits);
+ CR_COPY(op, hh->asce_limit, mm->context.asce_limit);
+}
+
+int cr_write_thread(struct cr_ctx *ctx, struct task_struct *t)
+{
+ return 0;
+}
+
+/* dump the cpu state and registers of a given task */
+int cr_write_cpu(struct cr_ctx *ctx, struct task_struct *t)
+{
+ struct cr_hdr h;
+ struct cr_hdr_cpu *hh = cr_hbuf_get(ctx, sizeof(*hh));
+ int ret;
+
+ h.type = CR_HDR_CPU;
+ h.len = sizeof(*hh);
+ h.parent = task_pid_vnr(t);
+
+ cr_s390_regs(CR_CPT, hh, t);
+
+ ret = cr_write_obj(ctx, &h, hh);
+ cr_hbuf_put(ctx, sizeof(*hh));
+
+ return ret;
+}
+
+/* Write an empty header since it is assumed to be there */
+int cr_write_head_arch(struct cr_ctx *ctx)
+{
+ struct cr_hdr h;
+ struct cr_hdr_head_arch *hh = cr_hbuf_get(ctx, sizeof(*hh));
+ int ret;
+
+ h.type = CR_HDR_HEAD_ARCH;
+ h.len = sizeof(*hh);
+ h.parent = 0;
+
+ ret = cr_write_obj(ctx, &h, &hh);
+ cr_hbuf_put(ctx, sizeof(*hh));
+
+ return ret;
+}
+
+int cr_write_mm_context(struct cr_ctx *ctx, struct mm_struct *mm, int parent)
+{
+ struct cr_hdr h;
+ struct cr_hdr_mm_context *hh = cr_hbuf_get(ctx, sizeof(*hh));
+ int ret;
+
+ h.type = CR_HDR_MM_CONTEXT;
+ h.len = sizeof(*hh);
+ h.parent = parent;
+
+ cr_s390_mm(CR_CPT, hh, mm);
+
+ ret = cr_write_obj(ctx, &h, hh);
+ cr_hbuf_put(ctx, sizeof(*hh));
+
+ return ret;
+}
diff --git a/arch/s390/mm/checkpoint_s390.h b/arch/s390/mm/checkpoint_s390.h
new file mode 100644
index 0000000..52a5e6f
--- /dev/null
+++ b/arch/s390/mm/checkpoint_s390.h
@@ -0,0 +1,22 @@
+/*
+ * 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 cr_s390_regs(int op, struct cr_hdr_cpu *hh, struct task_struct *t);
+extern void cr_s390_mm(int op, struct cr_hdr_mm_context *hh,
+ struct mm_struct *mm);
+
+#endif /* _S390_CHECKPOINT_H */
diff --git a/arch/s390/mm/restart.c b/arch/s390/mm/restart.c
new file mode 100644
index 0000000..7da4111
--- /dev/null
+++ b/arch/s390/mm/restart.c
@@ -0,0 +1,81 @@
+/*
+ * 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/checkpoint.h>
+#include <linux/checkpoint_hdr.h>
+#include <linux/kernel.h>
+#include <asm/system.h>
+#include <asm/pgtable.h>
+
+#include "checkpoint_s390.h"
+
+int cr_read_thread(struct cr_ctx *ctx)
+{
+ return 0;
+}
+
+int cr_read_cpu(struct cr_ctx *ctx)
+{
+ struct cr_hdr_cpu *hh = cr_hbuf_get(ctx, sizeof(*hh));
+ int parent, ret;
+
+ parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_CPU);
+ if (parent < 0) {
+ ret = parent;
+ goto out;
+ }
+ ret = 0;
+
+ cr_s390_regs(CR_RST, hh, 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(hh->acrs);
+out:
+ cr_hbuf_put(ctx, sizeof(*hh));
+ return ret;
+}
+
+int cr_read_head_arch(struct cr_ctx *ctx)
+{
+ struct cr_hdr_head_arch *hh = cr_hbuf_get(ctx, sizeof(*hh));
+ int parent, ret = 0;
+
+ parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_HEAD_ARCH);
+ if (parent < 0)
+ ret = parent;
+
+ cr_hbuf_put(ctx, sizeof(*hh));
+
+ return ret;
+}
+
+
+int cr_read_mm_context(struct cr_ctx *ctx, struct mm_struct *mm, int rparent)
+{
+ struct cr_hdr_mm_context *hh = cr_hbuf_get(ctx, sizeof(*hh));
+ int parent, ret = -EINVAL;
+
+ parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_MM_CONTEXT);
+ if (parent < 0) {
+ ret = parent;
+ goto out;
+ }
+ if (parent != rparent)
+ goto out;
+
+ cr_s390_mm(CR_RST, hh, mm);
+ ret = 0;
+ out:
+ cr_hbuf_put(ctx, sizeof(*hh));
+ return ret;
+}
diff --git a/checkpoint/Kconfig b/checkpoint/Kconfig
index ffaa635..cb1d29d 100644
--- a/checkpoint/Kconfig
+++ b/checkpoint/Kconfig
@@ -1,7 +1,7 @@
config CHECKPOINT_RESTART
prompt "Enable checkpoint/restart (EXPERIMENTAL)"
def_bool n
- depends on X86_32 && EXPERIMENTAL
+ depends on (X86_32 || (S390 && 64BIT)) && EXPERIMENTAL
help
Application checkpoint/restart is the ability to save the
state of a running application so that it can later resume
--
1.6.1