mm: add get_dump_page
In preparation for the next patch, add a simple get_dump_page(addr)
interface for the CONFIG_ELF_CORE dumpers to use, instead of calling
get_user_pages() directly. They're not interested in errors: they
just want to use holes as much as possible, to save space and make
sure that the data is aligned where the headers said it would be.
Oh, and don't use that horrid DUMP_SEEK(off) macro!
Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 7c1e65d..442d94f 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1280,9 +1280,6 @@
#define DUMP_WRITE(addr, nr) \
if ((size += (nr)) > limit || !dump_write(file, (addr), (nr))) \
goto end_coredump;
-#define DUMP_SEEK(off) \
- if (!dump_seek(file, (off))) \
- goto end_coredump;
static void fill_elf_header(struct elfhdr *elf, int segs,
u16 machine, u32 flags, u8 osabi)
@@ -2016,7 +2013,8 @@
goto end_coredump;
/* Align to page */
- DUMP_SEEK(dataoff - foffset);
+ if (!dump_seek(file, dataoff - foffset))
+ goto end_coredump;
for (vma = first_vma(current, gate_vma); vma != NULL;
vma = next_vma(vma, gate_vma)) {
@@ -2027,33 +2025,19 @@
for (addr = vma->vm_start; addr < end; addr += PAGE_SIZE) {
struct page *page;
- struct vm_area_struct *tmp_vma;
+ int stop;
- if (get_user_pages(current, current->mm, addr, 1, 0, 1,
- &page, &tmp_vma) <= 0) {
- DUMP_SEEK(PAGE_SIZE);
- } else {
- if (page == ZERO_PAGE(0)) {
- if (!dump_seek(file, PAGE_SIZE)) {
- page_cache_release(page);
- goto end_coredump;
- }
- } else {
- void *kaddr;
- flush_cache_page(tmp_vma, addr,
- page_to_pfn(page));
- kaddr = kmap(page);
- if ((size += PAGE_SIZE) > limit ||
- !dump_write(file, kaddr,
- PAGE_SIZE)) {
- kunmap(page);
- page_cache_release(page);
- goto end_coredump;
- }
- kunmap(page);
- }
+ page = get_dump_page(addr);
+ if (page) {
+ void *kaddr = kmap(page);
+ stop = ((size += PAGE_SIZE) > limit) ||
+ !dump_write(file, kaddr, PAGE_SIZE);
+ kunmap(page);
page_cache_release(page);
- }
+ } else
+ stop = !dump_seek(file, PAGE_SIZE);
+ if (stop)
+ goto end_coredump;
}
}
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 20fbece..7628547 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -1325,9 +1325,6 @@
#define DUMP_WRITE(addr, nr) \
if ((size += (nr)) > limit || !dump_write(file, (addr), (nr))) \
goto end_coredump;
-#define DUMP_SEEK(off) \
- if (!dump_seek(file, (off))) \
- goto end_coredump;
static inline void fill_elf_fdpic_header(struct elfhdr *elf, int segs)
{
@@ -1518,6 +1515,7 @@
unsigned long *limit, unsigned long mm_flags)
{
struct vm_area_struct *vma;
+ int err = 0;
for (vma = current->mm->mmap; vma; vma = vma->vm_next) {
unsigned long addr;
@@ -1525,43 +1523,26 @@
if (!maydump(vma, mm_flags))
continue;
- for (addr = vma->vm_start;
- addr < vma->vm_end;
- addr += PAGE_SIZE
- ) {
- struct vm_area_struct *vma;
- struct page *page;
-
- if (get_user_pages(current, current->mm, addr, 1, 0, 1,
- &page, &vma) <= 0) {
- DUMP_SEEK(file->f_pos + PAGE_SIZE);
- }
- else if (page == ZERO_PAGE(0)) {
- page_cache_release(page);
- DUMP_SEEK(file->f_pos + PAGE_SIZE);
- }
- else {
- void *kaddr;
-
- flush_cache_page(vma, addr, page_to_pfn(page));
- kaddr = kmap(page);
- if ((*size += PAGE_SIZE) > *limit ||
- !dump_write(file, kaddr, PAGE_SIZE)
- ) {
- kunmap(page);
- page_cache_release(page);
- return -EIO;
- }
+ for (addr = vma->vm_start; addr < vma->vm_end;
+ addr += PAGE_SIZE) {
+ struct page *page = get_dump_page(addr);
+ if (page) {
+ void *kaddr = kmap(page);
+ *size += PAGE_SIZE;
+ if (*size > *limit)
+ err = -EFBIG;
+ else if (!dump_write(file, kaddr, PAGE_SIZE))
+ err = -EIO;
kunmap(page);
page_cache_release(page);
- }
+ } else if (!dump_seek(file, file->f_pos + PAGE_SIZE))
+ err = -EFBIG;
+ if (err)
+ goto out;
}
}
-
- return 0;
-
-end_coredump:
- return -EFBIG;
+out:
+ return err;
}
#endif
@@ -1802,7 +1783,8 @@
goto end_coredump;
}
- DUMP_SEEK(dataoff);
+ if (!dump_seek(file, dataoff))
+ goto end_coredump;
if (elf_fdpic_dump_segments(file, &size, &limit, mm_flags) < 0)
goto end_coredump;
