[Devel] [PATCH 1/1] c/r: define s390-specific checkpoint-restart code (v3)
Serge E. Hallyn
serue at us.ibm.com
Tue Feb 3 08:12:23 PST 2009
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.
I'm having a strange problem with libraries though. If I link a
program with some extra libraries (-lm, -lcrypt, -lpthread,
whatever), then after restart, if I do a fprintf("%f), the program
segfaults. Not linking with extra libraries beside libc, or not
doing a fprintf of a float, doesn't cause any segfaults after
restart. ltrace and strace aren't helpful, and gdb says
that the restarted program faulted at __printf_fp@@GLIBC2.4.
objdump -d output shows no difference (of course, since this
is after linking), but mentions a __dso_handle which doesn't
look familiar compared to x86 output. /proc/$$/maps looks
the same on original and restarted task too. So I'm
flummoxed.
Changelog:
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 at us.ibm.com>
---
arch/s390/include/asm/checkpoint_hdr.h | 91 ++++++++++++++
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 | 206 ++++++++++++++++++++++++++++++++
checkpoint/Kconfig | 2 +-
7 files changed, 316 insertions(+), 2 deletions(-)
create mode 100644 arch/s390/include/asm/checkpoint_hdr.h
create mode 100644 arch/s390/mm/checkpoint.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..f11ec74
--- /dev/null
+++ b/arch/s390/include/asm/checkpoint_hdr.h
@@ -0,0 +1,91 @@
+#ifndef __ASM_S390_CKPT_HDR_H
+#define __ASM_S390_CKPT_HDR_H
+/*
+ * Checkpoint/restart - architecture specific headers s/390
+ *
+ * Copyright (C) 2008 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>
+
+/*
+ * 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(cr_hdr_task) on x86-32 is different from x86-64, since it
+ * will be 32-bit aligned on x86-32."
+ */
+
+#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
+ */
+struct cr_hdr_cpu {
+ __u64 args[1];
+ __u64 gprs[NUM_GPRS];
+ __u64 orig_gpr2;
+ __u16 svcnr;
+ __u16 ilc;
+ __u32 acrs[NUM_ACRS];
+ __u64 ksp;
+ __u64 prot_addr;
+ __u32 trap_no;
+ __u64 ieee_instruction_pointer;
+ __u64 pfault_wait;
+
+ /* mm_segment_t */
+ __u32 mm_segment_t_ar4;
+
+ /* psw_t */
+ __u64 psw_t_mask;
+ __u64 psw_t_addr;
+
+ /* s390_fp_regs_t */
+ __u32 fpc;
+ struct {
+ float f;
+ double d;
+ __u64 ui;
+ __u32 fp_hi;
+ __u32 fp_lo;
+ } fprs[NUM_FPRS];
+
+ /* per_struct */
+ __u64 per_control_regs[3];
+ __u32 em_instr;
+ __u64 starting_addr;
+ __u64 ending_addr;
+ __u16 perc_atmid;
+ __u64 address;
+ __u8 access_id;
+};
+
+struct cr_hdr_mm_context {
+ unsigned long vdso_base;
+};
+
+struct cr_hdr_head_arch {
+};
+#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..b3f0f32 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
diff --git a/arch/s390/mm/checkpoint.c b/arch/s390/mm/checkpoint.c
new file mode 100644
index 0000000..2c96493
--- /dev/null
+++ b/arch/s390/mm/checkpoint.c
@@ -0,0 +1,206 @@
+/*
+ * Checkpoint/restart - architecture specific support for s390
+ *
+ * Copyright (C) 2008 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.h>
+#include <linux/checkpoint_hdr.h>
+#include <linux/kernel.h>
+#include <asm/system.h>
+#include <asm/pgtable.h>
+
+int cr_write_thread(struct cr_ctx *ctx, struct task_struct *t)
+{
+ return 0;
+}
+
+static void cr_save_cpu_regs(struct cr_hdr_cpu *hh, struct task_struct *t)
+{
+ struct thread_struct *thread = &t->thread;
+ struct pt_regs *regs = task_pt_regs(t);
+
+ hh->fpc = thread->fp_regs.fpc;
+ memcpy(&hh->fprs, &thread->fp_regs.fprs, NUM_FPRS*sizeof(freg_t));
+ memcpy(hh->acrs, &thread->acrs[0], NUM_ACRS * sizeof(unsigned int));
+ hh->mm_segment_t_ar4 = thread->mm_segment.ar4;
+ hh->psw_t_mask = regs->psw.mask;
+ hh->psw_t_addr = regs->psw.addr;
+
+ hh->ksp = thread->ksp; /* unsure */
+
+ hh->args[0] = regs->args[0];
+ hh->svcnr = regs->svcnr;
+ hh->ilc = regs->ilc;
+ memcpy(hh->gprs, regs->gprs, NUM_GPRS*sizeof(unsigned long));
+ hh->orig_gpr2 = regs->orig_gpr2;
+
+ hh->prot_addr = thread->prot_addr;
+ hh->trap_no = thread->trap_no;
+ hh->ieee_instruction_pointer = thread->ieee_instruction_pointer;
+ hh->pfault_wait = thread->pfault_wait;
+
+ /* per_info */
+ memcpy(&hh->per_control_regs, &thread->per_info.control_regs.words,
+ 3 * sizeof(unsigned long));
+ hh->em_instr = 0;
+ if (thread->per_info.single_step)
+ hh->em_instr |= 1;
+ if (thread->per_info.instruction_fetch)
+ hh->em_instr |= 2;
+ hh->starting_addr = thread->per_info.starting_addr;
+ hh->ending_addr = thread->per_info.ending_addr;
+ hh->perc_atmid = thread->per_info.lowcore.words.perc_atmid;
+ hh->address = thread->per_info.lowcore.words.address;
+ hh->access_id = thread->per_info.lowcore.words.access_id;
+}
+
+/* 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_save_cpu_regs(hh, t);
+
+ ret = cr_write_obj(ctx, &h, hh);
+ cr_hbuf_put(ctx, sizeof(*hh));
+ WARN_ON_ONCE(ret < 0);
+
+ return ret;
+}
+
+int cr_write_head_arch(struct cr_ctx *ctx)
+{
+ return 0;
+}
+
+/* Nothing to do for mm context state */
+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;
+
+#if 0
+ /* Oren's v13 is on an older kernel which has no vdso_base */
+ /* on newer kernel, we'll have to enable this */
+ hh->vdso_base = mm->context.vdso_base;
+ printk(KERN_NOTICE "checkpointing vdso_base %lx\n", hh->vdso_base);
+#else
+ hh->vdso_base = 0;
+#endif
+
+ ret = cr_write_obj(ctx, &h, hh);
+ cr_hbuf_put(ctx, sizeof(*hh));
+
+ return ret;
+}
+
+/* restart APIs */
+
+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));
+ struct thread_struct *thread = ¤t->thread;
+ struct pt_regs *regs = task_pt_regs(current);
+ int parent, ret;
+
+ parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_CPU);
+ if (parent < 0) {
+ ret = parent;
+ goto out;
+ }
+ ret = 0;
+
+ regs->psw.addr &= ~PSW_ADDR_INSN;
+ regs->psw.addr |= hh->psw_t_addr & PSW_ADDR_INSN;
+
+ regs->args[0] = hh->args[0];
+ regs->svcnr = hh->svcnr;
+ regs->ilc = hh->ilc;
+ memcpy(regs->gprs, hh->gprs, NUM_GPRS*sizeof(unsigned long));
+ regs->orig_gpr2 = hh->orig_gpr2;
+
+ thread->ksp = hh->ksp; /* unsure */
+
+ memcpy(thread->acrs, hh->acrs, NUM_ACRS * sizeof(unsigned int));
+ thread->prot_addr = hh->prot_addr;
+ thread->trap_no = hh->trap_no;
+ thread->ieee_instruction_pointer = hh->ieee_instruction_pointer;
+ thread->pfault_wait = hh->pfault_wait;
+
+ /* s390_fp_regs_t */
+ thread->fp_regs.fpc = hh->fpc;
+ memcpy(&thread->fp_regs.fprs, &hh->fprs, NUM_FPRS*sizeof(freg_t));
+
+ thread->mm_segment.ar4 = hh->mm_segment_t_ar4;
+
+ /* per_struct */
+ memcpy(&thread->per_info.control_regs.words, &hh->per_control_regs,
+ 3 * sizeof(unsigned long));
+ if (hh->em_instr & 0x01)
+ thread->per_info.single_step = 1;
+ if (hh->em_instr & 0x02)
+ thread->per_info.instruction_fetch = 1;
+ thread->per_info.starting_addr = hh->starting_addr;
+ thread->per_info.ending_addr = hh->ending_addr;
+ thread->per_info.lowcore.words.perc_atmid = hh->perc_atmid;
+ thread->per_info.lowcore.words.address = hh->address;
+ thread->per_info.lowcore.words.access_id = hh->access_id;
+
+out:
+ cr_hbuf_put(ctx, sizeof(*hh));
+ return ret;
+}
+
+int cr_read_head_arch(struct cr_ctx *ctx)
+{
+ return 0;
+}
+
+
+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;
+
+ s390_enable_sie();
+
+ 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;
+
+#if 0
+ /* enable this when s390 defines vdso-base */
+ mm->context.vdso_base = hh->vdso_base;
+ printk(KERN_NOTICE "read vdso_base %lx\n", hh->vdso_base);
+#endif
+ 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
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