lkml.org 
[lkml]   [2008]   [Sep]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[RFC v4][PATCH 5/9] Memory managemnet (restore)
    Date
    Restoring the memory address space begins with nuking the existing one
    of the current process, and then reading the VMA state and contents.
    Call do_mmap_pgoffset() for each VMA and then read in the data.

    Signed-off-by: Oren Laadan <orenl@cs.columbia.edu>
    ---
    arch/x86/mm/checkpoint.c | 5 +-
    arch/x86/mm/restart.c | 54 +++++++
    checkpoint/Makefile | 2 +-
    checkpoint/ckpt_arch.h | 2 +
    checkpoint/restart.c | 43 ++++++
    checkpoint/rstr_mem.c | 351 ++++++++++++++++++++++++++++++++++++++++++++
    include/asm-x86/ckpt_hdr.h | 4 +
    include/linux/ckpt.h | 2 +
    include/linux/ckpt_hdr.h | 2 +-
    9 files changed, 460 insertions(+), 5 deletions(-)
    create mode 100644 checkpoint/rstr_mem.c

    diff --git a/arch/x86/mm/checkpoint.c b/arch/x86/mm/checkpoint.c
    index 50cfd29..534684f 100644
    --- a/arch/x86/mm/checkpoint.c
    +++ b/arch/x86/mm/checkpoint.c
    @@ -208,17 +208,16 @@ int cr_write_mm_context(struct cr_ctx *ctx, struct mm_struct *mm, int parent)

    hh->ldt_entry_size = LDT_ENTRY_SIZE;
    hh->nldt = mm->context.size;
    -
    cr_debug("nldt %d\n", hh->nldt);

    ret = cr_write_obj(ctx, &h, hh);
    cr_hbuf_put(ctx, sizeof(*hh));
    if (ret < 0)
    - return ret;
    + goto out;

    ret = cr_kwrite(ctx, mm->context.ldt, hh->nldt * LDT_ENTRY_SIZE);

    mutex_unlock(&mm->context.lock);
    -
    + out:
    return ret;
    }
    diff --git a/arch/x86/mm/restart.c b/arch/x86/mm/restart.c
    index d7fb89a..be5e0cd 100644
    --- a/arch/x86/mm/restart.c
    +++ b/arch/x86/mm/restart.c
    @@ -177,3 +177,57 @@ int cr_read_cpu(struct cr_ctx *ctx)
    out:
    return ret;
    }
    +
    +int cr_read_mm_context(struct cr_ctx *ctx, struct mm_struct *mm, int parent)
    +{
    + struct cr_hdr_mm_context *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + int n, rparent;
    +
    + rparent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_MM_CONTEXT);
    + cr_debug("parent %d rparent %d nldt %d\n", parent, rparent, hh->nldt);
    + if (rparent < 0)
    + return rparent;
    + if (rparent != parent)
    + return -EINVAL;
    +
    + if (hh->nldt < 0 || hh->ldt_entry_size != LDT_ENTRY_SIZE)
    + return -EINVAL;
    +
    + /* to utilize the syscall modify_ldt() we first convert the data
    + * in the checkpoint image from 'struct desc_struct' to 'struct
    + * user_desc' with reverse logic of include/asm/desc.h:fill_ldt() */
    +
    + for (n = 0; n < hh->nldt; n++) {
    + struct user_desc info;
    + struct desc_struct desc;
    + mm_segment_t old_fs;
    + int ret;
    +
    + ret = cr_kread(ctx, &desc, LDT_ENTRY_SIZE);
    + if (ret < 0)
    + return ret;
    +
    + info.entry_number = n;
    + info.base_addr = desc.base0 | (desc.base1 << 16);
    + info.limit = desc.limit0;
    + info.seg_32bit = desc.d;
    + info.contents = desc.type >> 2;
    + info.read_exec_only = (desc.type >> 1) ^ 1;
    + info.limit_in_pages = desc.g;
    + info.seg_not_present = desc.p ^ 1;
    + info.useable = desc.avl;
    +
    + old_fs = get_fs();
    + set_fs(get_ds());
    + ret = sys_modify_ldt(1, &info, sizeof(info));
    + set_fs(old_fs);
    +
    + if (ret < 0)
    + return ret;
    + }
    +
    + load_LDT(&mm->context);
    +
    + cr_hbuf_put(ctx, sizeof(*hh));
    + return 0;
    +}
    diff --git a/checkpoint/Makefile b/checkpoint/Makefile
    index 3a0df6d..ac35033 100644
    --- a/checkpoint/Makefile
    +++ b/checkpoint/Makefile
    @@ -3,4 +3,4 @@
    #

    obj-$(CONFIG_CHECKPOINT_RESTART) += sys.o checkpoint.o restart.o \
    - ckpt_mem.o
    + ckpt_mem.o rstr_mem.o
    diff --git a/checkpoint/ckpt_arch.h b/checkpoint/ckpt_arch.h
    index 9bd0ba4..29dd326 100644
    --- a/checkpoint/ckpt_arch.h
    +++ b/checkpoint/ckpt_arch.h
    @@ -6,3 +6,5 @@ int cr_write_mm_context(struct cr_ctx *ctx, struct mm_struct *mm, int parent);

    int cr_read_thread(struct cr_ctx *ctx);
    int cr_read_cpu(struct cr_ctx *ctx);
    +int cr_read_mm_context(struct cr_ctx *ctx, struct mm_struct *mm, int parent);
    +
    diff --git a/checkpoint/restart.c b/checkpoint/restart.c
    index 5226994..f8c919d 100644
    --- a/checkpoint/restart.c
    +++ b/checkpoint/restart.c
    @@ -77,6 +77,45 @@ int cr_read_string(struct cr_ctx *ctx, void *str, int len)
    return cr_read_obj_type(ctx, str, len, CR_HDR_STRING);
    }

    +/**
    + * cr_read_fname - read a file name
    + * @ctx: checkpoint context
    + * @fname: buffer
    + * @n: buffer length
    + */
    +int cr_read_fname(struct cr_ctx *ctx, void *fname, int flen)
    +{
    + return cr_read_obj_type(ctx, fname, flen, CR_HDR_FNAME);
    +}
    +
    +/**
    + * cr_read_open_fname - read a file name and open a file
    + * @ctx: checkpoint context
    + * @flags: file flags
    + * @mode: file mode
    + */
    +struct file *cr_read_open_fname(struct cr_ctx *ctx, int flags, int mode)
    +{
    + struct file *file;
    + char *fname;
    + int flen, ret;
    +
    + flen = PATH_MAX;
    + fname = kmalloc(flen, GFP_KERNEL);
    + if (!fname)
    + return ERR_PTR(-ENOMEM);
    +
    + ret = cr_read_fname(ctx, fname, flen);
    + cr_debug("fname '%s' flags %#x mode %#x\n", fname, flags, mode);
    + if (ret >= 0)
    + file = filp_open(fname, flags, mode);
    + else
    + file = ERR_PTR(ret);
    +
    + kfree(fname);
    + return file;
    +}
    +
    /* read the checkpoint header */
    static int cr_read_head(struct cr_ctx *ctx)
    {
    @@ -169,6 +208,10 @@ static int cr_read_task(struct cr_ctx *ctx)
    cr_debug("task_struct: ret %d\n", ret);
    if (ret < 0)
    goto out;
    + ret = cr_read_mm(ctx);
    + cr_debug("memory: ret %d\n", ret);
    + if (ret < 0)
    + goto out;
    ret = cr_read_thread(ctx);
    cr_debug("thread: ret %d\n", ret);
    if (ret < 0)
    diff --git a/checkpoint/rstr_mem.c b/checkpoint/rstr_mem.c
    new file mode 100644
    index 0000000..106b635
    --- /dev/null
    +++ b/checkpoint/rstr_mem.c
    @@ -0,0 +1,351 @@
    +/*
    + * Restart memory contents
    + *
    + * 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/kernel.h>
    +#include <linux/sched.h>
    +#include <linux/fcntl.h>
    +#include <linux/file.h>
    +#include <linux/fs.h>
    +#include <linux/uaccess.h>
    +#include <linux/mm_types.h>
    +#include <linux/mman.h>
    +#include <linux/mm.h>
    +#include <linux/err.h>
    +#include <asm/cacheflush.h>
    +#include <linux/ckpt.h>
    +#include <linux/ckpt_hdr.h>
    +
    +#include "ckpt_arch.h"
    +#include "ckpt_mem.h"
    +
    +/*
    + * Unlike checkpoint, restart is executed in the context of each restarting
    + * process: vma regions are restored via a call to mmap(), and the data is
    + * read in directly to the address space of the current process
    + */
    +
    +/**
    + * cr_vma_read_pages_vaddrs - read addresses of pages to page-array chain
    + * @ctx - restart context
    + * @npages - number of pages
    + */
    +static int cr_vma_read_pages_vaddrs(struct cr_ctx *ctx, int npages)
    +{
    + struct cr_pgarr *pgarr;
    + int nr, ret;
    +
    + while (npages) {
    + pgarr = cr_pgarr_prep(ctx);
    + if (!pgarr)
    + return -ENOMEM;
    + nr = min(npages, (int) pgarr->nr_free);
    + ret = cr_kread(ctx, pgarr->vaddrs, nr * sizeof(unsigned long));
    + if (ret < 0)
    + return ret;
    + pgarr->nr_free -= nr;
    + pgarr->nr_used += nr;
    + npages -= nr;
    + }
    + return 0;
    +}
    +
    +/**
    + * cr_vma_read_pages_contents - read in data of pages in page-array chain
    + * @ctx - restart context
    + * @npages - number of pages
    + */
    +static int cr_vma_read_pages_contents(struct cr_ctx *ctx, int npages)
    +{
    + struct cr_pgarr *pgarr;
    + unsigned long *vaddrs;
    + int i, ret;
    +
    + list_for_each_entry(pgarr, &ctx->pgarr, list) {
    + vaddrs = pgarr->vaddrs;
    + for (i = 0; i < pgarr->nr_used; i++) {
    + void *ptr = (void *) vaddrs[i];
    + ret = cr_uread(ctx, ptr, PAGE_SIZE);
    + if (ret < 0)
    + return ret;
    + }
    + npages -= pgarr->nr_used;
    + }
    + return 0;
    +}
    +
    +/* change the protection of an address range to be writable/non-writable.
    + * this is useful when restoring the memory of a read-only vma */
    +static int cr_vma_set_writable(struct mm_struct *mm, unsigned long start,
    + unsigned long end, int writable)
    +{
    + struct vm_area_struct *vma, *prev;
    + unsigned long flags = 0;
    + int ret = -EINVAL;
    +
    + cr_debug("vma %#lx-%#lx writable %d\n", start, end, writable);
    +
    + down_write(&mm->mmap_sem);
    + vma = find_vma_prev(mm, start, &prev);
    + if (!vma || vma->vm_start > end || vma->vm_end < start)
    + goto out;
    + if (writable && !(vma->vm_flags & VM_WRITE))
    + flags = vma->vm_flags | VM_WRITE;
    + else if (!writable && (vma->vm_flags & VM_WRITE))
    + flags = vma->vm_flags & ~VM_WRITE;
    + cr_debug("flags %#lx\n", flags);
    + if (flags)
    + ret = mprotect_fixup(vma, &prev, vma->vm_start,
    + vma->vm_end, flags);
    + out:
    + up_write(&mm->mmap_sem);
    + return ret;
    +}
    +
    +/**
    + * cr_vma_read_pages - read in pages for to restore a vma
    + * @ctx - restart context
    + * @cr_vma - vma descriptor from restart
    + */
    +static int cr_vma_read_pages(struct cr_ctx *ctx, struct cr_hdr_vma *hh)
    +{
    + struct mm_struct *mm = current->mm;
    + int ret = 0;
    +
    + if (!hh->nr_pages)
    + return 0;
    +
    + /* in the unlikely case that this vma is read-only */
    + if (!(hh->vm_flags & VM_WRITE))
    + ret = cr_vma_set_writable(mm, hh->vm_start, hh->vm_end, 1);
    + if (ret < 0)
    + goto out;
    + ret = cr_vma_read_pages_vaddrs(ctx, hh->nr_pages);
    + if (ret < 0)
    + goto out;
    + ret = cr_vma_read_pages_contents(ctx, hh->nr_pages);
    + if (ret < 0)
    + goto out;
    +
    + cr_pgarr_reset(ctx); /* reset page-array chain */
    +
    + /* restore original protection for this vma */
    + if (!(hh->vm_flags & VM_WRITE))
    + ret = cr_vma_set_writable(mm, hh->vm_start, hh->vm_end, 0);
    +
    + out:
    + return ret;
    +}
    +
    +/**
    + * cr_calc_map_prot_bits - convert vm_flags to mmap protection
    + * orig_vm_flags: source vm_flags
    + */
    +static unsigned long cr_calc_map_prot_bits(unsigned long orig_vm_flags)
    +{
    + unsigned long vm_prot = 0;
    +
    + if (orig_vm_flags & VM_READ)
    + vm_prot |= PROT_READ;
    + if (orig_vm_flags & VM_WRITE)
    + vm_prot |= PROT_WRITE;
    + if (orig_vm_flags & VM_EXEC)
    + vm_prot |= PROT_EXEC;
    + if (orig_vm_flags & PROT_SEM) /* only (?) with IPC-SHM */
    + vm_prot |= PROT_SEM;
    +
    + return vm_prot;
    +}
    +
    +/**
    + * cr_calc_map_flags_bits - convert vm_flags to mmap flags
    + * orig_vm_flags: source vm_flags
    + */
    +static unsigned long cr_calc_map_flags_bits(unsigned long orig_vm_flags)
    +{
    + unsigned long vm_flags = 0;
    +
    + vm_flags = MAP_FIXED;
    + if (orig_vm_flags & VM_GROWSDOWN)
    + vm_flags |= MAP_GROWSDOWN;
    + if (orig_vm_flags & VM_DENYWRITE)
    + vm_flags |= MAP_DENYWRITE;
    + if (orig_vm_flags & VM_EXECUTABLE)
    + vm_flags |= MAP_EXECUTABLE;
    + if (orig_vm_flags & VM_MAYSHARE)
    + vm_flags |= MAP_SHARED;
    + else
    + vm_flags |= MAP_PRIVATE;
    +
    + return vm_flags;
    +}
    +
    +static int cr_read_vma(struct cr_ctx *ctx, struct mm_struct *mm)
    +{
    + struct cr_hdr_vma *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + unsigned long vm_size, vm_start, vm_flags, vm_prot, vm_pgoff;
    + unsigned long addr;
    + unsigned long flags;
    + struct file *file = NULL;
    + int parent, ret = 0;
    +
    + parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_VMA);
    + if (parent < 0)
    + return parent;
    + else if (parent != 0)
    + return -EINVAL;
    +
    + cr_debug("vma %#lx-%#lx type %d nr_pages %d\n",
    + (unsigned long) hh->vm_start, (unsigned long) hh->vm_end,
    + (int) hh->vma_type, (int) hh->nr_pages);
    +
    + if (hh->vm_end < hh->vm_start || hh->nr_pages < 0)
    + return -EINVAL;
    +
    + vm_start = hh->vm_start;
    + vm_pgoff = hh->vm_pgoff;
    + vm_size = hh->vm_end - hh->vm_start;
    + vm_prot = cr_calc_map_prot_bits(hh->vm_flags);
    + vm_flags = cr_calc_map_flags_bits(hh->vm_flags);
    +
    + switch (hh->vma_type) {
    +
    + case CR_VMA_ANON: /* anonymous private mapping */
    + /* vm_pgoff for anonymous mapping is the "global" page
    + offset (namely from addr 0x0), so we force a zero */
    + vm_pgoff = 0;
    + break;
    +
    + case CR_VMA_FILE: /* private mapping from a file */
    + /* O_RDWR only needed if both (VM_WRITE|VM_SHARED) are set */
    + flags = hh->vm_flags;
    + if ((flags & (VM_WRITE|VM_SHARED)) == (VM_WRITE|VM_SHARED))
    + flags = O_RDWR;
    + else
    + flags = O_RDONLY;
    + file = cr_read_open_fname(ctx, flags, 0);
    + if (IS_ERR(file))
    + return PTR_ERR(file);
    + break;
    +
    + default:
    + return -EINVAL;
    +
    + }
    +
    + down_write(&mm->mmap_sem);
    + addr = do_mmap_pgoff(file, vm_start, vm_size,
    + vm_prot, vm_flags, vm_pgoff);
    + up_write(&mm->mmap_sem);
    + cr_debug("size %#lx prot %#lx flag %#lx pgoff %#lx => %#lx\n",
    + vm_size, vm_prot, vm_flags, vm_pgoff, addr);
    +
    + /* the file (if opened) is now referenced by the vma */
    + if (file)
    + filp_close(file, NULL);
    +
    + if (IS_ERR((void *) addr))
    + return PTR_ERR((void *) addr);
    +
    + /*
    + * CR_VMA_ANON: read in memory as is
    + * CR_VMA_FILE: read in memory as is
    + * (more to follow ...)
    + */
    +
    + switch (hh->vma_type) {
    + case CR_VMA_ANON:
    + case CR_VMA_FILE:
    + /* standard case: read the data into the memory */
    + ret = cr_vma_read_pages(ctx, hh);
    + break;
    + }
    +
    + if (ret < 0)
    + return ret;
    +
    + cr_hbuf_put(ctx, sizeof(*hh));
    + cr_debug("vma retval %d\n", ret);
    + return 0;
    +}
    +
    +static int cr_destroy_mm(struct mm_struct *mm)
    +{
    + struct vm_area_struct *vmnext = mm->mmap;
    + struct vm_area_struct *vma;
    + int ret;
    +
    + while (vmnext) {
    + vma = vmnext;
    + vmnext = vmnext->vm_next;
    + ret = do_munmap(mm, vma->vm_start, vma->vm_end-vma->vm_start);
    + if (ret < 0) {
    + pr_debug("CR: restart failed do_munmap (%d)\n", ret);
    + return ret;
    + }
    + }
    + return 0;
    +}
    +
    +int cr_read_mm(struct cr_ctx *ctx)
    +{
    + struct cr_hdr_mm *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + struct mm_struct *mm;
    + int nr, parent, ret;
    +
    + parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_MM);
    + if (parent < 0)
    + return parent;
    +#if 0 /* activate when containers are used */
    + if (parent != task_pid_vnr(current))
    + return -EINVAL;
    +#endif
    + cr_debug("map_count %d\n", hh->map_count);
    +
    + /* XXX need more sanity checks */
    + if (hh->start_code > hh->end_code ||
    + hh->start_data > hh->end_data || hh->map_count < 0)
    + return -EINVAL;
    +
    + mm = current->mm;
    +
    + /* point of no return -- destruct current mm */
    + down_write(&mm->mmap_sem);
    + ret = cr_destroy_mm(mm);
    + if (ret < 0) {
    + up_write(&mm->mmap_sem);
    + return ret;
    + }
    + mm->start_code = hh->start_code;
    + mm->end_code = hh->end_code;
    + mm->start_data = hh->start_data;
    + mm->end_data = hh->end_data;
    + mm->start_brk = hh->start_brk;
    + mm->brk = hh->brk;
    + mm->start_stack = hh->start_stack;
    + mm->arg_start = hh->arg_start;
    + mm->arg_end = hh->arg_end;
    + mm->env_start = hh->env_start;
    + mm->env_end = hh->env_end;
    + up_write(&mm->mmap_sem);
    +
    +
    + /* FIX: need also mm->flags */
    +
    + for (nr = hh->map_count; nr; nr--) {
    + ret = cr_read_vma(ctx, mm);
    + if (ret < 0)
    + return ret;
    + }
    +
    + ret = cr_read_mm_context(ctx, mm, hh->objref);
    +
    + cr_hbuf_put(ctx, sizeof(*hh));
    + return ret;
    +}
    diff --git a/include/asm-x86/ckpt_hdr.h b/include/asm-x86/ckpt_hdr.h
    index 6bc61ac..f8eee6a 100644
    --- a/include/asm-x86/ckpt_hdr.h
    +++ b/include/asm-x86/ckpt_hdr.h
    @@ -74,4 +74,8 @@ struct cr_hdr_mm_context {
    __s16 nldt;
    } __attribute__((aligned(8)));

    +
    +/* misc prototypes from kernel (not defined elsewhere) */
    +asmlinkage int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount);
    +
    #endif /* __ASM_X86_CKPT_HDR__H */
    diff --git a/include/linux/ckpt.h b/include/linux/ckpt.h
    index 5c62a90..9305e7b 100644
    --- a/include/linux/ckpt.h
    +++ b/include/linux/ckpt.h
    @@ -59,6 +59,8 @@ int cr_write_fname(struct cr_ctx *ctx, struct path *path, struct path *root);
    int cr_read_obj(struct cr_ctx *ctx, struct cr_hdr *h, void *buf, int n);
    int cr_read_obj_type(struct cr_ctx *ctx, void *buf, int n, int type);
    int cr_read_string(struct cr_ctx *ctx, void *str, int len);
    +int cr_read_fname(struct cr_ctx *ctx, void *fname, int n);
    +struct file *cr_read_open_fname(struct cr_ctx *ctx, int flags, int mode);

    int cr_write_mm(struct cr_ctx *ctx, struct task_struct *t);
    int cr_read_mm(struct cr_ctx *ctx);
    diff --git a/include/linux/ckpt_hdr.h b/include/linux/ckpt_hdr.h
    index ac77d7d..f064cbb 100644
    --- a/include/linux/ckpt_hdr.h
    +++ b/include/linux/ckpt_hdr.h
    @@ -102,7 +102,7 @@ enum vm_type {
    struct cr_hdr_vma {
    __u32 vma_type;
    __u32 _padding;
    - __s64 nr_pages;
    + __s64 nr_pages; /* number of pages saved */

    __u64 vm_start;
    __u64 vm_end;
    --
    1.5.4.3


    \
     
     \ /
      Last update: 2008-09-09 09:51    [W:0.054 / U:180.184 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site