Messages in this thread | | | Date | Mon, 15 Sep 2008 16:31:58 -0500 | From | "Serge E. Hallyn" <> | Subject | Re: [RFC v5][PATCH 3/8] x86 support for checkpoint/restart |
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Quoting Oren Laadan (orenl@cs.columbia.edu): > (Following Dave Hansen's refactoring of the original post) > > Add logic to save and restore architecture specific state, including > thread-specific state, CPU registers and FPU state. > > Currently only x86-32 is supported. Compiling on x86-64 will trigger > an explicit error. > > Signed-off-by: Oren Laadan <orenl@cs.columbia.edu>
Acked-by: Serge Hallyn <serue@us.ibm.com>
> --- > arch/x86/mm/Makefile | 2 + > arch/x86/mm/checkpoint.c | 198 ++++++++++++++++++++++++++++++++++++++ > arch/x86/mm/restart.c | 177 ++++++++++++++++++++++++++++++++++ > checkpoint/checkpoint.c | 13 +++- > checkpoint/checkpoint_arch.h | 7 ++ > checkpoint/restart.c | 13 +++- > include/asm-x86/checkpoint_hdr.h | 72 ++++++++++++++ > include/linux/checkpoint_hdr.h | 1 + > 8 files changed, 481 insertions(+), 2 deletions(-) > create mode 100644 arch/x86/mm/checkpoint.c > create mode 100644 arch/x86/mm/restart.c > create mode 100644 checkpoint/checkpoint_arch.h > create mode 100644 include/asm-x86/checkpoint_hdr.h > > diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile > index dfb932d..58fe072 100644 > --- a/arch/x86/mm/Makefile > +++ b/arch/x86/mm/Makefile > @@ -22,3 +22,5 @@ endif > obj-$(CONFIG_ACPI_NUMA) += srat_$(BITS).o > > obj-$(CONFIG_MEMTEST) += memtest.o > + > +obj-$(CONFIG_CHECKPOINT_RESTART) += checkpoint.o restart.o > diff --git a/arch/x86/mm/checkpoint.c b/arch/x86/mm/checkpoint.c > new file mode 100644 > index 0000000..eb60003 > --- /dev/null > +++ b/arch/x86/mm/checkpoint.c > @@ -0,0 +1,198 @@ > +/* > + * Checkpoint/restart - architecture specific support for x86 > + * > + * 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 <asm/desc.h> > +#include <asm/i387.h> > + > +#include <linux/checkpoint.h> > +#include <linux/checkpoint_hdr.h> > + > +/* dump the thread_struct of a given task */ > +int cr_write_thread(struct cr_ctx *ctx, struct task_struct *t) > +{ > + struct cr_hdr h; > + struct cr_hdr_thread *hh = cr_hbuf_get(ctx, sizeof(*hh)); > + struct thread_struct *thread; > + struct desc_struct *desc; > + int ntls = 0; > + int n, ret; > + > + h.type = CR_HDR_THREAD; > + h.len = sizeof(*hh); > + h.parent = task_pid_vnr(t); > + > + 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++; > + } > + > + hh->gdt_entry_tls_entries = GDT_ENTRY_TLS_ENTRIES; > + hh->sizeof_tls_array = sizeof(thread->tls_array); > + hh->ntls = ntls; > + > + ret = cr_write_obj(ctx, &h, hh); > + cr_hbuf_put(ctx, sizeof(*hh)); > + if (ret < 0) > + return ret; > + > + /* for simplicity dump the entire array, cherry-pick upon restart */ > + ret = cr_kwrite(ctx, thread->tls_array, sizeof(thread->tls_array)); > + > + cr_debug("ntls %d\n", ntls); > + > + /* IGNORE RESTART BLOCKS FOR NOW ... */ > + > + return ret; > +} > + > +#ifdef CONFIG_X86_64 > + > +#error "CONFIG_X86_64 unsupported yet." > + > +#else /* !CONFIG_X86_64 */ > + > +void cr_write_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->bp = regs->bp; > + hh->bx = regs->bx; > + hh->ax = regs->ax; > + hh->cx = regs->cx; > + hh->dx = regs->dx; > + hh->si = regs->si; > + hh->di = regs->di; > + hh->orig_ax = regs->orig_ax; > + hh->ip = regs->ip; > + hh->cs = regs->cs; > + hh->flags = regs->flags; > + hh->sp = regs->sp; > + hh->ss = regs->ss; > + > + hh->ds = regs->ds; > + hh->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, hh->gs); > + savesegment(fs, hh->fs); > + } else { > + hh->gs = thread->gs; > + hh->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(hh->orig_ax < 0); > + hh->ax = 0; > + } > +} > + > +void cr_write_cpu_debug(struct cr_hdr_cpu *hh, struct task_struct *t) > +{ > + struct thread_struct *thread = &t->thread; > + > + /* debug regs */ > + > + preempt_disable(); > + > + /* > + * for checkpoint in process context (from within a container), > + * get the actual registers; otherwise get the saved values. > + */ > + > + if (t == current) { > + get_debugreg(hh->debugreg0, 0); > + get_debugreg(hh->debugreg1, 1); > + get_debugreg(hh->debugreg2, 2); > + get_debugreg(hh->debugreg3, 3); > + get_debugreg(hh->debugreg6, 6); > + get_debugreg(hh->debugreg7, 7); > + } else { > + hh->debugreg0 = thread->debugreg0; > + hh->debugreg1 = thread->debugreg1; > + hh->debugreg2 = thread->debugreg2; > + hh->debugreg3 = thread->debugreg3; > + hh->debugreg6 = thread->debugreg6; > + hh->debugreg7 = thread->debugreg7; > + } > + > + hh->debugreg4 = 0; > + hh->debugreg5 = 0; > + > + hh->uses_debug = !!(task_thread_info(t)->flags & TIF_DEBUG); > + > + preempt_enable(); > +} > + > +void cr_write_cpu_fpu(struct cr_hdr_cpu *hh, struct task_struct *t) > +{ > + struct thread_struct *thread = &t->thread; > + struct thread_info *thread_info = task_thread_info(t); > + > + /* i387 + MMU + SSE logic */ > + > + preempt_disable(); > + > + hh->used_math = tsk_used_math(t) ? 1 : 0; > + if (hh->used_math) { > + /* > + * normally, no need to unlazy_fpu(), since TS_USEDFPU flag > + * have been cleared when task was conexted-switched out... > + * except if we are in process context, in which case we do > + */ > + if (thread_info->status & TS_USEDFPU) > + unlazy_fpu(current); > + > + hh->has_fxsr = cpu_has_fxsr; > + memcpy(&hh->xstate, &thread->xstate, sizeof(thread->xstate)); > + } > + > + preempt_enable(); > +} > + > +#endif /* CONFIG_X86_64 */ > + > +/* 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_write_cpu_regs(hh, t); > + cr_write_cpu_debug(hh, t); > + cr_write_cpu_fpu(hh, t); > + > + cr_debug("math %d debug %d\n", hh->used_math, hh->uses_debug); > + > + ret = cr_write_obj(ctx, &h, hh); > + cr_hbuf_put(ctx, sizeof(*hh)); > + return ret; > +} > diff --git a/arch/x86/mm/restart.c b/arch/x86/mm/restart.c > new file mode 100644 > index 0000000..0178080 > --- /dev/null > +++ b/arch/x86/mm/restart.c > @@ -0,0 +1,177 @@ > +/* > + * Checkpoint/restart - architecture specific support for x86 > + * > + * 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 <asm/desc.h> > +#include <asm/i387.h> > + > +#include <linux/checkpoint.h> > +#include <linux/checkpoint_hdr.h> > + > +/* read the thread_struct into the current task */ > +int cr_read_thread(struct cr_ctx *ctx) > +{ > + struct cr_hdr_thread *hh = cr_hbuf_get(ctx, sizeof(*hh)); > + struct task_struct *t = current; > + struct thread_struct *thread = &t->thread; > + int parent; > + > + parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_THREAD); > + if (parent < 0) > + return parent; > +#if 0 /* activate when containers are used */ > + if (parent != task_pid_vnr(t)) > + return -EINVAL; > +#endif > + cr_debug("ntls %d\n", hh->ntls); > + > + if (hh->gdt_entry_tls_entries != GDT_ENTRY_TLS_ENTRIES || > + hh->sizeof_tls_array != sizeof(thread->tls_array) || > + hh->ntls < 0 || hh->ntls > GDT_ENTRY_TLS_ENTRIES) > + return -EINVAL; > + > + if (hh->ntls > 0) { > + struct desc_struct *desc; > + int size, cpu, ret; > + > + /* > + * restore TLS by hand: why convert to struct user_desc if > + * sys_set_thread_entry() will convert it back ? > + */ > + > + size = sizeof(*desc) * GDT_ENTRY_TLS_ENTRIES; > + desc = kmalloc(size, GFP_KERNEL); > + if (!desc) > + return -ENOMEM; > + > + ret = cr_kread(ctx, desc, size); > + if (ret >= 0) { > + /* > + * FIX: add sanity checks (eg. that values makes > + * sense, that we don't overwrite old values, etc > + */ > + cpu = get_cpu(); > + memcpy(thread->tls_array, desc, size); > + load_TLS(thread, cpu); > + put_cpu(); > + } > + kfree(desc); > + } > + > + return 0; > +} > + > +#ifdef CONFIG_X86_64 > + > +#error "CONFIG_X86_64 unsupported yet." > + > +#else /* !CONFIG_X86_64 */ > + > +int cr_read_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); > + > + regs->bx = hh->bx; > + regs->cx = hh->cx; > + regs->dx = hh->dx; > + regs->si = hh->si; > + regs->di = hh->di; > + regs->bp = hh->bp; > + regs->ax = hh->ax; > + regs->ds = hh->ds; > + regs->es = hh->es; > + regs->orig_ax = hh->orig_ax; > + regs->ip = hh->ip; > + regs->cs = hh->cs; > + regs->flags = hh->flags; > + regs->sp = hh->sp; > + regs->ss = hh->ss; > + > + thread->gs = hh->gs; > + thread->fs = hh->fs; > + loadsegment(gs, hh->gs); > + loadsegment(fs, hh->fs); > + > + return 0; > +} > + > +int cr_read_cpu_debug(struct cr_hdr_cpu *hh, struct task_struct *t) > +{ > + /* debug regs */ > + > + if (hh->uses_debug) { > + set_debugreg(hh->debugreg0, 0); > + set_debugreg(hh->debugreg1, 1); > + /* ignore 4, 5 */ > + set_debugreg(hh->debugreg2, 2); > + set_debugreg(hh->debugreg3, 3); > + set_debugreg(hh->debugreg6, 6); > + set_debugreg(hh->debugreg7, 7); > + } > + > + return 0; > +} > + > +int cr_read_cpu_fpu(struct cr_hdr_cpu *hh, struct task_struct *t) > +{ > + struct thread_struct *thread = &t->thread; > + > + /* i387 + MMU + SSE */ > + > + preempt_disable(); > + > + __clear_fpu(t); /* in case we used FPU in user mode */ > + > + if (!hh->used_math) > + clear_used_math(); > + else { > + if (hh->has_fxsr != cpu_has_fxsr) { > + force_sig(SIGFPE, t); > + return -EINVAL; > + } > + memcpy(&thread->xstate, &hh->xstate, sizeof(thread->xstate)); > + set_used_math(); > + } > + > + preempt_enable(); > + > + return 0; > +} > + > +#endif /* CONFIG_X86_64 */ > + > +/* read the cpu state and registers for the current task */ > +int cr_read_cpu(struct cr_ctx *ctx) > +{ > + struct cr_hdr_cpu *hh = cr_hbuf_get(ctx, sizeof(*hh)); > + struct task_struct *t = current; > + int parent, ret; > + > + parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_CPU); > + if (parent < 0) > + return parent; > +#if 0 /* activate when containers are used */ > + if (parent != task_pid_vnr(t)) > + return -EINVAL; > +#endif > + /* FIX: sanity check for sensitive registers (eg. eflags) */ > + > + ret = cr_read_cpu_regs(hh, t); > + if (ret < 0) > + goto out; > + ret = cr_read_cpu_debug(hh, t); > + if (ret < 0) > + goto out; > + ret = cr_read_cpu_fpu(hh, t); > + > + cr_debug("math %d debug %d\n", hh->used_math, hh->uses_debug); > + out: > + return ret; > +} > diff --git a/checkpoint/checkpoint.c b/checkpoint/checkpoint.c > index e5e188f..6ca26d0 100644 > --- a/checkpoint/checkpoint.c > +++ b/checkpoint/checkpoint.c > @@ -20,6 +20,8 @@ > #include <linux/checkpoint.h> > #include <linux/checkpoint_hdr.h> > > +#include "checkpoint_arch.h" > + > /** > * cr_write_obj - write a record described by a cr_hdr > * @ctx: checkpoint context > @@ -145,8 +147,17 @@ static int cr_write_task(struct cr_ctx *ctx, struct task_struct *t) > } > > ret = cr_write_task_struct(ctx, t); > - cr_debug("ret %d\n", ret); > + cr_debug("task_struct: ret %d\n", ret); > + if (ret < 0) > + goto out; > + ret = cr_write_thread(ctx, t); > + cr_debug("thread: ret %d\n", ret); > + if (ret < 0) > + goto out; > + ret = cr_write_cpu(ctx, t); > + cr_debug("cpu: ret %d\n", ret); > > + out: > return ret; > } > > diff --git a/checkpoint/checkpoint_arch.h b/checkpoint/checkpoint_arch.h > new file mode 100644 > index 0000000..bf2d21e > --- /dev/null > +++ b/checkpoint/checkpoint_arch.h > @@ -0,0 +1,7 @@ > +#include <linux/checkpoint.h> > + > +extern int cr_write_thread(struct cr_ctx *ctx, struct task_struct *t); > +extern int cr_write_cpu(struct cr_ctx *ctx, struct task_struct *t); > + > +extern int cr_read_thread(struct cr_ctx *ctx); > +extern int cr_read_cpu(struct cr_ctx *ctx); > diff --git a/checkpoint/restart.c b/checkpoint/restart.c > index ef6bc37..0484de0 100644 > --- a/checkpoint/restart.c > +++ b/checkpoint/restart.c > @@ -15,6 +15,8 @@ > #include <linux/checkpoint.h> > #include <linux/checkpoint_hdr.h> > > +#include "checkpoint_arch.h" > + > /** > * cr_read_obj - read a whole record (cr_hdr followed by payload) > * @ctx: checkpoint context > @@ -164,8 +166,17 @@ static int cr_read_task(struct cr_ctx *ctx) > int ret; > > ret = cr_read_task_struct(ctx); > - cr_debug("ret %d\n", ret); > + cr_debug("task_struct: ret %d\n", ret); > + if (ret < 0) > + goto out; > + ret = cr_read_thread(ctx); > + cr_debug("thread: ret %d\n", ret); > + if (ret < 0) > + goto out; > + ret = cr_read_cpu(ctx); > + cr_debug("cpu: ret %d\n", ret); > > + out: > return ret; > } > > diff --git a/include/asm-x86/checkpoint_hdr.h b/include/asm-x86/checkpoint_hdr.h > new file mode 100644 > index 0000000..44a903c > --- /dev/null > +++ b/include/asm-x86/checkpoint_hdr.h > @@ -0,0 +1,72 @@ > +#ifndef __ASM_X86_CKPT_HDR_H > +#define __ASM_X86_CKPT_HDR_H > +/* > + * Checkpoint/restart - architecture specific headers x86 > + * > + * 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 <asm/processor.h> > + > +struct cr_hdr_thread { > + /* NEED: restart blocks */ > + > + __s16 gdt_entry_tls_entries; > + __s16 sizeof_tls_array; > + __s16 ntls; /* number of TLS entries to follow */ > +} __attribute__((aligned(8))); > + > +struct cr_hdr_cpu { > + /* 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 debugreg4; > + __u64 debugreg5; > + __u64 debugreg6; > + __u64 debugreg7; > + > + __u16 uses_debug; > + __u16 used_math; > + __u16 has_fxsr; > + __u16 _padding; > + > + union thread_xstate xstate; /* i387 */ > + > +} __attribute__((aligned(8))); > + > +#endif /* __ASM_X86_CKPT_HDR__H */ > diff --git a/include/linux/checkpoint_hdr.h b/include/linux/checkpoint_hdr.h > index 79e4df2..03ec72e 100644 > --- a/include/linux/checkpoint_hdr.h > +++ b/include/linux/checkpoint_hdr.h > @@ -12,6 +12,7 @@ > > #include <linux/types.h> > #include <linux/utsname.h> > +#include <asm/checkpoint_hdr.h> > > /* > * To maintain compatibility between 32-bit and 64-bit architecture flavors, > -- > 1.5.4.3 > > _______________________________________________ > Containers mailing list > Containers@lists.linux-foundation.org > https://lists.linux-foundation.org/mailman/listinfo/containers
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