The patch titled
Subject: coredump: refactor page range dumping into common helper
has been added to the -mm tree. Its filename is
coredump-refactor-page-range-dumping-into-common-helper.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/coredump-refactor-page-range-dumping-into-common-helper.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/coredump-refactor-page-range-dumping-into-common-helper.patch
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------------------------------------------------------
From: Jann Horn <jannh@xxxxxxxxxx>
Subject: 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.
Link: http://lkml.kernel.org/r/20200827114932.3572699-4-jannh@xxxxxxxxxx
Signed-off-by: Jann Horn <jannh@xxxxxxxxxx>
Acked-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: "Eric W . Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/binfmt_elf.c | 22 ++--------------------
fs/binfmt_elf_fdpic.c | 18 +++---------------
fs/coredump.c | 34 ++++++++++++++++++++++++++++++++++
include/linux/coredump.h | 2 ++
4 files changed, 41 insertions(+), 35 deletions(-)
--- a/fs/binfmt_elf.c~coredump-refactor-page-range-dumping-into-common-helper
+++ a/fs/binfmt_elf.c
@@ -2444,26 +2444,8 @@ static int elf_core_dump(struct coredump
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);
--- a/fs/binfmt_elf_fdpic.c~coredump-refactor-page-range-dumping-into-common-helper
+++ a/fs/binfmt_elf_fdpic.c
@@ -1534,21 +1534,9 @@ static bool elf_fdpic_dump_segments(stru
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;
}
--- a/fs/coredump.c~coredump-refactor-page-range-dumping-into-common-helper
+++ a/fs/coredump.c
@@ -876,6 +876,40 @@ int dump_skip(struct coredump_params *cp
}
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);
--- a/include/linux/coredump.h~coredump-refactor-page-range-dumping-into-common-helper
+++ a/include/linux/coredump.h
@@ -16,6 +16,8 @@ extern int dump_skip(struct coredump_par
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
_
Patches currently in -mm which might be from jannh@xxxxxxxxxx are
binfmt_elf_fdpic-stop-using-dump_emit-on-user-pointers-on-mmu.patch
coredump-let-dump_emit-bail-out-on-short-writes.patch
coredump-refactor-page-range-dumping-into-common-helper.patch
coredump-rework-elf-elf_fdpic-vma_dump_size-into-common-helper.patch
binfmt_elf-binfmt_elf_fdpic-use-a-vma-list-snapshot.patch
mm-gup-take-mmap_lock-in-get_dump_page.patch
mm-remove-the-now-unnecessary-mmget_still_valid-hack.patch
