coredump: refactor page range dumping into common helper
Both fs/binfmt_elf.c and fs/binfmt_elf_fdpic.c need to dump ranges of
pages into the coredump file. Extract that logic into a common helper.
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Link: http://lkml.kernel.org/r/20200827114932.3572699-4-jannh@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 96370e3..cf956ed 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -2444,26 +2444,8 @@
for (i = 0, vma = first_vma(current, gate_vma); vma != NULL;
vma = next_vma(vma, gate_vma)) {
- unsigned long addr;
- unsigned long end;
-
- end = vma->vm_start + vma_filesz[i++];
-
- for (addr = vma->vm_start; addr < end; addr += PAGE_SIZE) {
- struct page *page;
- int stop;
-
- page = get_dump_page(addr);
- if (page) {
- void *kaddr = kmap(page);
- stop = !dump_emit(cprm, kaddr, PAGE_SIZE);
- kunmap(page);
- put_page(page);
- } else
- stop = !dump_skip(cprm, PAGE_SIZE);
- if (stop)
- goto end_coredump;
- }
+ if (!dump_user_range(cprm, vma->vm_start, vma_filesz[i++]))
+ goto end_coredump;
}
dump_truncate(cprm);
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index a53f838..76e8c0d 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -1534,21 +1534,9 @@
if (!maydump(vma, cprm->mm_flags))
continue;
- for (addr = vma->vm_start; addr < vma->vm_end;
- addr += PAGE_SIZE) {
- bool res;
- struct page *page = get_dump_page(addr);
- if (page) {
- void *kaddr = kmap(page);
- res = dump_emit(cprm, kaddr, PAGE_SIZE);
- kunmap(page);
- put_page(page);
- } else {
- res = dump_skip(cprm, PAGE_SIZE);
- }
- if (!res)
- return false;
- }
+ if (!dump_user_range(cprm, vma->vm_start,
+ vma->vma_end - vma->vm_start))
+ return false;
}
return true;
}
diff --git a/fs/coredump.c b/fs/coredump.c
index 5e24c06..6042d15 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -876,6 +876,40 @@
}
EXPORT_SYMBOL(dump_skip);
+#ifdef CONFIG_ELF_CORE
+int dump_user_range(struct coredump_params *cprm, unsigned long start,
+ unsigned long len)
+{
+ unsigned long addr;
+
+ for (addr = start; addr < start + len; addr += PAGE_SIZE) {
+ struct page *page;
+ int stop;
+
+ /*
+ * To avoid having to allocate page tables for virtual address
+ * ranges that have never been used yet, and also to make it
+ * easy to generate sparse core files, use a helper that returns
+ * NULL when encountering an empty page table entry that would
+ * otherwise have been filled with the zero page.
+ */
+ page = get_dump_page(addr);
+ if (page) {
+ void *kaddr = kmap(page);
+
+ stop = !dump_emit(cprm, kaddr, PAGE_SIZE);
+ kunmap(page);
+ put_page(page);
+ } else {
+ stop = !dump_skip(cprm, PAGE_SIZE);
+ }
+ if (stop)
+ return 0;
+ }
+ return 1;
+}
+#endif
+
int dump_align(struct coredump_params *cprm, int align)
{
unsigned mod = cprm->pos & (align - 1);
diff --git a/include/linux/coredump.h b/include/linux/coredump.h
index 7a899e8..f0b71a74 100644
--- a/include/linux/coredump.h
+++ b/include/linux/coredump.h
@@ -16,6 +16,8 @@
extern int dump_emit(struct coredump_params *cprm, const void *addr, int nr);
extern int dump_align(struct coredump_params *cprm, int align);
extern void dump_truncate(struct coredump_params *cprm);
+int dump_user_range(struct coredump_params *cprm, unsigned long start,
+ unsigned long len);
#ifdef CONFIG_COREDUMP
extern void do_coredump(const kernel_siginfo_t *siginfo);
#else
