[PATCH v8 3/6] vmcore: Introduce remap_oldmem_pfn_range()
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
Acked-by: Vivek Goyal
cc: HATAYAMA Daisuke
---
fs/proc/vmcore.c | 91 ++
include/linux/crash_dump.h | 3 ++
2 files changed, 86 insertions(+), 8 deletions(-)
diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 02cb3ff..3f6cf0e 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 +154,35 @@ 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, , 1);
+ tmp = read_from_oldmem(buffer, tsz, , userbuf);
if (tmp < 0)
return tmp;
buflen -= tsz;
@@ -225,6 +250,55 @@ 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.
+ *
+ * On s390 the fault handler is used for memory regions that can't be mapped
+ * directly with remap_pfn_range().
+ */
+static int mmap_vmcore_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+#ifdef CONFIG_S390
+ struct address_space *mapping = vma->vm_file->f_mapping;
+ pgoff_t index = vmf->pgoff;
+ struct page *page;
+ loff_t offset;
+ char *buf;
+ int rc;
+
+ page = find_or_create_page(mapping, index, GFP_KERNEL);
+ if (!page)
+
[PATCH v8 3/6] vmcore: Introduce remap_oldmem_pfn_range()
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 holz...@linux.vnet.ibm.com
Acked-by: Vivek Goyal vgo...@redhat.com
cc: HATAYAMA Daisuke d.hatay...@jp.fujitsu.com
---
fs/proc/vmcore.c | 91 ++
include/linux/crash_dump.h | 3 ++
2 files changed, 86 insertions(+), 8 deletions(-)
diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 02cb3ff..3f6cf0e 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 +250,55 @@ 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.
+ *
+ * On s390 the fault handler is used for memory regions that can't be mapped
+ * directly with remap_pfn_range().
+ */
+static int mmap_vmcore_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+#ifdef CONFIG_S390
+ struct address_space *mapping = vma-vm_file-f_mapping;
+ pgoff_t index = vmf-pgoff;
+ struct page *page;
+
