[PATCH v2 20/20] vmcore: introduce mmap_vmcore()
This patch introduces mmap_vmcore(). If flag MEM_TYPE_CURRENT_KERNEL is set, remapped is the buffer on the 2nd kernel. If not set, remapped is some area in old memory. Neither writable nor executable mapping is permitted even with mprotect(). Non-writable mapping is also requirement of remap_pfn_range() when mapping linear pages on non-consequtive physical pages; see is_cow_mapping(). On x86-32 PAE kernels, mmap() supports at most 16TB memory only. This limitation comes from the fact that the third argument of remap_pfn_range(), pfn, is of 32-bit length on x86-32: unsigned long. Signed-off-by: HATAYAMA Daisuke --- fs/proc/vmcore.c | 72 ++ 1 files changed, 72 insertions(+), 0 deletions(-) diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c index 709d21a..9433ef0 100644 --- a/fs/proc/vmcore.c +++ b/fs/proc/vmcore.c @@ -185,9 +185,81 @@ static ssize_t read_vmcore(struct file *file, char __user *buffer, return acc; } +static int mmap_vmcore(struct file *file, struct vm_area_struct *vma) +{ + size_t size = vma->vm_end - vma->vm_start; + u64 start, end, len, tsz; + struct vmcore *m; + + if (!support_mmap_vmcore) + return -ENODEV; + + start = (u64)vma->vm_pgoff << PAGE_SHIFT; + end = start + size; + + if (size > vmcore_size || end > vmcore_size) + return -EINVAL; + + if (vma->vm_flags & (VM_WRITE | VM_EXEC)) + return -EPERM; + + vma->vm_flags &= ~(VM_MAYWRITE | VM_MAYEXEC); + + len = 0; + + if (start < elfcorebuf_sz) { + u64 pfn; + + tsz = elfcorebuf_sz - start; + if (size < tsz) + tsz = size; + pfn = __pa(elfcorebuf + start) >> PAGE_SHIFT; + if (remap_pfn_range(vma, vma->vm_start, pfn, tsz, + vma->vm_page_prot)) + return -EAGAIN; + size -= tsz; + start += tsz; + len += tsz; + + if (size == 0) + return 0; + } + + list_for_each_entry(m, _list, list) { + if (start < m->offset + m->size) { + u64 pfn = 0; + + tsz = m->offset + m->size - start; + if (size < tsz) + tsz = size; + if (m->flag & MEM_TYPE_CURRENT_KERNEL) { + pfn = __pa(m->buf + start - m->offset) + >> PAGE_SHIFT; + } else { + pfn = (m->paddr + (start - m->offset)) + >> PAGE_SHIFT; + } + if (remap_pfn_range(vma, vma->vm_start + len, pfn, tsz, + vma->vm_page_prot)) { + do_munmap(vma->vm_mm, vma->vm_start, len); + return -EAGAIN; + } + size -= tsz; + start += tsz; + len += tsz; + + if (size == 0) + return 0; + } + } + + return 0; +} + static const struct file_operations proc_vmcore_operations = { .read = read_vmcore, .llseek = default_llseek, + .mmap = mmap_vmcore, }; static struct vmcore* __init get_new_element(void) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH v2 20/20] vmcore: introduce mmap_vmcore()
This patch introduces mmap_vmcore(). If flag MEM_TYPE_CURRENT_KERNEL is set, remapped is the buffer on the 2nd kernel. If not set, remapped is some area in old memory. Neither writable nor executable mapping is permitted even with mprotect(). Non-writable mapping is also requirement of remap_pfn_range() when mapping linear pages on non-consequtive physical pages; see is_cow_mapping(). On x86-32 PAE kernels, mmap() supports at most 16TB memory only. This limitation comes from the fact that the third argument of remap_pfn_range(), pfn, is of 32-bit length on x86-32: unsigned long. Signed-off-by: HATAYAMA Daisuke d.hatay...@jp.fujitsu.com --- fs/proc/vmcore.c | 72 ++ 1 files changed, 72 insertions(+), 0 deletions(-) diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c index 709d21a..9433ef0 100644 --- a/fs/proc/vmcore.c +++ b/fs/proc/vmcore.c @@ -185,9 +185,81 @@ static ssize_t read_vmcore(struct file *file, char __user *buffer, return acc; } +static int mmap_vmcore(struct file *file, struct vm_area_struct *vma) +{ + size_t size = vma-vm_end - vma-vm_start; + u64 start, end, len, tsz; + struct vmcore *m; + + if (!support_mmap_vmcore) + return -ENODEV; + + start = (u64)vma-vm_pgoff PAGE_SHIFT; + end = start + size; + + if (size vmcore_size || end vmcore_size) + return -EINVAL; + + if (vma-vm_flags (VM_WRITE | VM_EXEC)) + return -EPERM; + + vma-vm_flags = ~(VM_MAYWRITE | VM_MAYEXEC); + + len = 0; + + if (start elfcorebuf_sz) { + u64 pfn; + + tsz = elfcorebuf_sz - start; + if (size tsz) + tsz = size; + pfn = __pa(elfcorebuf + start) PAGE_SHIFT; + if (remap_pfn_range(vma, vma-vm_start, pfn, tsz, + vma-vm_page_prot)) + return -EAGAIN; + size -= tsz; + start += tsz; + len += tsz; + + if (size == 0) + return 0; + } + + list_for_each_entry(m, vmcore_list, list) { + if (start m-offset + m-size) { + u64 pfn = 0; + + tsz = m-offset + m-size - start; + if (size tsz) + tsz = size; + if (m-flag MEM_TYPE_CURRENT_KERNEL) { + pfn = __pa(m-buf + start - m-offset) +PAGE_SHIFT; + } else { + pfn = (m-paddr + (start - m-offset)) +PAGE_SHIFT; + } + if (remap_pfn_range(vma, vma-vm_start + len, pfn, tsz, + vma-vm_page_prot)) { + do_munmap(vma-vm_mm, vma-vm_start, len); + return -EAGAIN; + } + size -= tsz; + start += tsz; + len += tsz; + + if (size == 0) + return 0; + } + } + + return 0; +} + static const struct file_operations proc_vmcore_operations = { .read = read_vmcore, .llseek = default_llseek, + .mmap = mmap_vmcore, }; static struct vmcore* __init get_new_element(void) -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/