On Mon, Jul 01, 2013 at 09:32:37PM +0200, Michael Holzheu wrote: > For zfcpdump we can't map the HSA storage because it is only available > via a read interface. Therefore, for the new vmcore mmap feature we have > introduce a new mechanism to create mappings on demand. > > This patch introduces a new architecture function remap_oldmem_pfn_range() > that should be used to create mappings with remap_pfn_range() for oldmem > areas that can be directly mapped. For zfcpdump this is everything besides > of the HSA memory. For the areas that are not mapped by > remap_oldmem_pfn_range() > a generic vmcore a new generic vmcore fault handler mmap_vmcore_fault() > is called. > > This handler works as follows: > > * Get already available or new page from page cache (find_or_create_page) > * Check if /proc/vmcore page is filled with data (PageUptodate) > * If yes: > Return that page > * If no: > Fill page using __vmcore_read(), set PageUptodate, and return page > > Signed-off-by: Michael Holzheu <[email protected]>
In general vmcore related changes look fine to me. I am not very familiar with the logic of finding pages in page cache and using page uptodate flag. Hatayama, can you please review it. Acked-by: Vivek Goyal <[email protected]> Thanks Vivek > --- > fs/proc/vmcore.c | 84 > +++++++++++++++++++++++++++++++++++++++++----- > include/linux/crash_dump.h | 3 ++ > 2 files changed, 79 insertions(+), 8 deletions(-) > > diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c > index c28189c..77312c7 100644 > --- a/fs/proc/vmcore.c > +++ b/fs/proc/vmcore.c > @@ -21,6 +21,7 @@ > #include <linux/crash_dump.h> > #include <linux/list.h> > #include <linux/vmalloc.h> > +#include <linux/pagemap.h> > #include <asm/uaccess.h> > #include <asm/io.h> > #include "internal.h" > @@ -153,11 +154,35 @@ ssize_t __weak elfcorehdr_read_notes(char *buf, size_t > count, u64 *ppos) > return read_from_oldmem(buf, count, ppos, 0); > } > > +/* > + * Architectures may override this function to map oldmem > + */ > +int __weak remap_oldmem_pfn_range(struct vm_area_struct *vma, > + unsigned long from, unsigned long pfn, > + unsigned long size, pgprot_t prot) > +{ > + return remap_pfn_range(vma, from, pfn, size, prot); > +} > + > +/* > + * Copy to either kernel or user space > + */ > +static int copy_to(void *target, void *src, size_t size, int userbuf) > +{ > + if (userbuf) { > + if (copy_to_user(target, src, size)) > + return -EFAULT; > + } else { > + memcpy(target, src, size); > + } > + return 0; > +} > + > /* Read from the ELF header and then the crash dump. On error, negative > value is > * returned otherwise number of bytes read are returned. > */ > -static ssize_t read_vmcore(struct file *file, char __user *buffer, > - size_t buflen, loff_t *fpos) > +static ssize_t __read_vmcore(char *buffer, size_t buflen, loff_t *fpos, > + int userbuf) > { > ssize_t acc = 0, tmp; > size_t tsz; > @@ -174,7 +199,7 @@ static ssize_t read_vmcore(struct file *file, char __user > *buffer, > /* Read ELF core header */ > if (*fpos < elfcorebuf_sz) { > tsz = min(elfcorebuf_sz - (size_t)*fpos, buflen); > - if (copy_to_user(buffer, elfcorebuf + *fpos, tsz)) > + if (copy_to(buffer, elfcorebuf + *fpos, tsz, userbuf)) > return -EFAULT; > buflen -= tsz; > *fpos += tsz; > @@ -192,7 +217,7 @@ static ssize_t read_vmcore(struct file *file, char __user > *buffer, > > tsz = min(elfcorebuf_sz + elfnotes_sz - (size_t)*fpos, buflen); > kaddr = elfnotes_buf + *fpos - elfcorebuf_sz; > - if (copy_to_user(buffer, kaddr, tsz)) > + if (copy_to(buffer, kaddr, tsz, userbuf)) > return -EFAULT; > buflen -= tsz; > *fpos += tsz; > @@ -208,7 +233,7 @@ static ssize_t read_vmcore(struct file *file, char __user > *buffer, > if (*fpos < m->offset + m->size) { > tsz = min_t(size_t, m->offset + m->size - *fpos, > buflen); > start = m->paddr + *fpos - m->offset; > - tmp = read_from_oldmem(buffer, tsz, &start, 1); > + tmp = read_from_oldmem(buffer, tsz, &start, userbuf); > if (tmp < 0) > return tmp; > buflen -= tsz; > @@ -225,6 +250,48 @@ static ssize_t read_vmcore(struct file *file, char > __user *buffer, > return acc; > } > > +static ssize_t read_vmcore(struct file *file, char __user *buffer, > + size_t buflen, loff_t *fpos) > +{ > + return __read_vmcore(buffer, buflen, fpos, 1); > +} > + > +/* > + * The vmcore fault handler uses the page cache and fills data using the > + * standard __vmcore_read() function. > + */ > +static int mmap_vmcore_fault(struct vm_area_struct *vma, struct vm_fault > *vmf) > +{ > + struct address_space *mapping = vma->vm_file->f_mapping; > + pgoff_t index = vmf->pgoff; > + struct page *page; > + loff_t src; > + char *buf; > + int rc; > + > + page = find_or_create_page(mapping, index, GFP_KERNEL); > + if (!page) > + return VM_FAULT_OOM; > + if (!PageUptodate(page)) { > + src = index << PAGE_CACHE_SHIFT; > + buf = (void *) (page_to_pfn(page) << PAGE_SHIFT); > + rc = __read_vmcore(buf, PAGE_SIZE, &src, 0); > + if (rc < 0) { > + unlock_page(page); > + page_cache_release(page); > + return (rc == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS; > + } > + SetPageUptodate(page); > + } > + unlock_page(page); > + vmf->page = page; > + return 0; > +} > + > +static const struct vm_operations_struct vmcore_mmap_ops = { > + .fault = mmap_vmcore_fault, > +}; > + > static int mmap_vmcore(struct file *file, struct vm_area_struct *vma) > { > size_t size = vma->vm_end - vma->vm_start; > @@ -242,6 +309,7 @@ static int mmap_vmcore(struct file *file, struct > vm_area_struct *vma) > > vma->vm_flags &= ~(VM_MAYWRITE | VM_MAYEXEC); > vma->vm_flags |= VM_MIXEDMAP; > + vma->vm_ops = &vmcore_mmap_ops; > > len = 0; > > @@ -283,9 +351,9 @@ static int mmap_vmcore(struct file *file, struct > vm_area_struct *vma) > > tsz = min_t(size_t, m->offset + m->size - start, size); > paddr = m->paddr + start - m->offset; > - if (remap_pfn_range(vma, vma->vm_start + len, > - paddr >> PAGE_SHIFT, tsz, > - vma->vm_page_prot)) > + if (remap_oldmem_pfn_range(vma, vma->vm_start + len, > + paddr >> PAGE_SHIFT, tsz, > + vma->vm_page_prot)) > goto fail; > size -= tsz; > start += tsz; > diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h > index 6571f82..fe68a5a 100644 > --- a/include/linux/crash_dump.h > +++ b/include/linux/crash_dump.h > @@ -17,6 +17,9 @@ extern int __weak elfcorehdr_alloc(unsigned long long *addr, > extern void __weak elfcorehdr_free(unsigned long long addr); > extern ssize_t __weak elfcorehdr_read(char *buf, size_t count, u64 *ppos); > extern ssize_t __weak elfcorehdr_read_notes(char *buf, size_t count, u64 > *ppos); > +extern int __weak remap_oldmem_pfn_range(struct vm_area_struct *vma, > + unsigned long from, unsigned long pfn, > + unsigned long size, pgprot_t prot); > > extern ssize_t copy_oldmem_page(unsigned long, char *, size_t, > unsigned long, int); > -- > 1.8.2.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
