Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756810Ab3FGQ4V (ORCPT ); Fri, 7 Jun 2013 12:56:21 -0400 Received: from e06smtp17.uk.ibm.com ([195.75.94.113]:58703 "EHLO e06smtp17.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756478Ab3FGQ4H (ORCPT ); Fri, 7 Jun 2013 12:56:07 -0400 From: Michael Holzheu To: Vivek Goyal Cc: HATAYAMA Daisuke , Jan Willeke , Martin Schwidefsky , Heiko Carstens , linux-kernel@vger.kernel.org, kexec@lists.infradead.org Subject: [PATCH v5 3/5] vmcore: Introduce remap_oldmem_pfn_range() Date: Fri, 7 Jun 2013 18:55:59 +0200 Message-Id: <1370624161-2298-4-git-send-email-holzheu@linux.vnet.ibm.com> X-Mailer: git-send-email 1.8.1.6 In-Reply-To: <1370624161-2298-1-git-send-email-holzheu@linux.vnet.ibm.com> References: <1370624161-2298-1-git-send-email-holzheu@linux.vnet.ibm.com> X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13060716-0542-0000-0000-0000057AC7EC Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6736 Lines: 204 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 does the following: * Check if /proc/vmcore page cache page is already available * If yes: - Return that page * If no: - Allocate new page - Fill page using __vmcore_read() - Add new page to page cache Signed-off-by: Michael Holzheu --- fs/proc/vmcore.c | 94 ++++++++++++++++++++++++++++++++++++++++++---- include/linux/crash_dump.h | 3 ++ 2 files changed, 89 insertions(+), 8 deletions(-) diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c index 221f84b..259a639 100644 --- a/fs/proc/vmcore.c +++ b/fs/proc/vmcore.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include #include "internal.h" @@ -153,11 +154,36 @@ 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; + return 0; + } 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 +200,7 @@ 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 +218,7 @@ 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 +234,7 @@ 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 +251,56 @@ 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_private_data; + pgoff_t index = vmf->pgoff; + struct page *page; + loff_t src; + char *buf; + int rc; + +find_page: + page = find_lock_page(mapping, index); + if (page) { + unlock_page(page); + rc = VM_FAULT_MINOR; + } else { + page = page_cache_alloc_cold(mapping); + if (!page) + return VM_FAULT_OOM; + rc = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL); + if (rc) { + page_cache_release(page); + if (rc == -EEXIST) + goto find_page; + /* Probably ENOMEM for radix tree node */ + return VM_FAULT_OOM; + } + buf = (void *) (page_to_pfn(page) << PAGE_SHIFT); + src = index << PAGE_CACHE_SHIFT; + __read_vmcore(buf, PAGE_SIZE, &src, 0); + unlock_page(page); + rc = VM_FAULT_MAJOR; + } + vmf->page = page; + return rc; +} + +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 +318,8 @@ 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; + vma->vm_private_data = file->f_mapping; len = 0; @@ -283,9 +361,9 @@ 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 dd0f434..c0818de 100644 --- a/include/linux/crash_dump.h +++ b/include/linux/crash_dump.h @@ -16,6 +16,9 @@ extern int __weak elfcorehdr_alloc(void); extern void __weak elfcorehdr_free(void); 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); -- 1.8.1.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/