coredump: add DAX filtering for ELF coredumps (5037835c) · Commits · 戴 / test

Documentation/filesystems/proc.txt

+12 −10

Original line number	Diff line number	Diff line
		@@ -1598,16 +1598,16 @@ Documentation/accounting.
		---------------------------------------------------------------
		When a process is dumped, all anonymous memory is written to a core file as
		long as the size of the core file isn't limited. But sometimes we don't want
		to dump some memory segments, for example, huge shared memory. Conversely,
		sometimes we want to save file-backed memory segments into a core file, not
		only the individual files.
		to dump some memory segments, for example, huge shared memory or DAX.
		Conversely, sometimes we want to save file-backed memory segments into a core
		file, not only the individual files.

		/proc/<pid>/coredump_filter allows you to customize which memory segments
		will be dumped when the <pid> process is dumped. coredump_filter is a bitmask
		of memory types. If a bit of the bitmask is set, memory segments of the
		corresponding memory type are dumped, otherwise they are not dumped.

		The following 7 memory types are supported:
		The following 9 memory types are supported:
		- (bit 0) anonymous private memory
		- (bit 1) anonymous shared memory
		- (bit 2) file-backed private memory
		@@ -1616,20 +1616,22 @@ The following 7 memory types are supported:
		effective only if the bit 2 is cleared)
		- (bit 5) hugetlb private memory
		- (bit 6) hugetlb shared memory
		- (bit 7) DAX private memory
		- (bit 8) DAX shared memory

		Note that MMIO pages such as frame buffer are never dumped and vDSO pages
		are always dumped regardless of the bitmask status.

		Note bit 0-4 doesn't effect any hugetlb memory. hugetlb memory are only
		effected by bit 5-6.
		Note that bits 0-4 don't affect hugetlb or DAX memory. hugetlb memory is
		only affected by bit 5-6, and DAX is only affected by bits 7-8.

		Default value of coredump_filter is 0x23; this means all anonymous memory
		segments and hugetlb private memory are dumped.
		The default value of coredump_filter is 0x33; this means all anonymous memory
		segments, ELF header pages and hugetlb private memory are dumped.

		If you don't want to dump all shared memory segments attached to pid 1234,
		write 0x21 to the process's proc file.
		write 0x31 to the process's proc file.

		$ echo 0x21 > /proc/1234/coredump_filter
		$ echo 0x31 > /proc/1234/coredump_filter

		When a new process is created, the process inherits the bitmask status from its
		parent. It is useful to set up coredump_filter before the program runs.

fs/binfmt_elf.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -35,6 +35,7 @@
		#include <linux/utsname.h>
		#include <linux/coredump.h>
		#include <linux/sched.h>
		#include <linux/dax.h>
		#include <asm/uaccess.h>
		#include <asm/param.h>
		#include <asm/page.h>
		@@ -1236,6 +1237,15 @@ static unsigned long vma_dump_size(struct vm_area_struct *vma,
		if (vma->vm_flags & VM_DONTDUMP)
		return 0;

		/* support for DAX */
		if (vma_is_dax(vma)) {
		if ((vma->vm_flags & VM_SHARED) && FILTER(DAX_SHARED))
		goto whole;
		if (!(vma->vm_flags & VM_SHARED) && FILTER(DAX_PRIVATE))
		goto whole;
		return 0;
		}

		/* Hugetlb memory check */
		if (vma->vm_flags & VM_HUGETLB) {
		if ((vma->vm_flags & VM_SHARED) && FILTER(HUGETLB_SHARED))

include/linux/sched.h

+3 −1

Original line number	Diff line number	Diff line
		@@ -483,9 +483,11 @@ static inline int get_dumpable(struct mm_struct *mm)
		#define MMF_DUMP_ELF_HEADERS 6
		#define MMF_DUMP_HUGETLB_PRIVATE 7
		#define MMF_DUMP_HUGETLB_SHARED 8
		#define MMF_DUMP_DAX_PRIVATE 9
		#define MMF_DUMP_DAX_SHARED 10

		#define MMF_DUMP_FILTER_SHIFT MMF_DUMPABLE_BITS
		#define MMF_DUMP_FILTER_BITS 7
		#define MMF_DUMP_FILTER_BITS 9
		#define MMF_DUMP_FILTER_MASK \
		(((1 << MMF_DUMP_FILTER_BITS) - 1) << MMF_DUMP_FILTER_SHIFT)
		#define MMF_DUMP_FILTER_DEFAULT \

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