[merged] coredump-refactor-page-range-dumping-into-common-helper.patch removed from -mm tree

[merged] coredump-refactor-page-range-dumping-into-common-helper.patch removed from -mm tree

[akpm]

The patch titled
     Subject: coredump: refactor page range dumping into common helper
has been removed from the -mm tree.  Its filename was
     coredump-refactor-page-range-dumping-into-common-helper.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: Jann Horn <jannh@google.com>
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@google.com
Signed-off-by: Jann Horn <jannh@google.com>
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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 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@google.com are

mm-gup_benchmark-take-the-mmap-lock-around-gup.patch
binfmt_elf-take-the-mmap-lock-around-find_extend_vma.patch
mmap-locking-api-dont-check-locking-if-the-mm-isnt-live-yet.patch
mm-gup-assert-that-the-mmap-lock-is-held-in-__get_user_pages.patch