The patch titled
Subject: proc/kcore: add vmcoreinfo note to /proc/kcore
has been added to the -mm tree. Its filename is
proc-kcore-add-vmcoreinfo-note-to-proc-kcore.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/proc-kcore-add-vmcoreinfo-note-to-proc-kcore.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/proc-kcore-add-vmcoreinfo-note-to-proc-kcore.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Omar Sandoval <osandov@xxxxxx>
Subject: proc/kcore: add vmcoreinfo note to /proc/kcore
The vmcoreinfo information is useful for runtime debugging tools, not just
for crash dumps. A lot of this information can be determined by other
means, but this is much more convenient, and it only adds a page at most
to the file.
Link: http://lkml.kernel.org/r/fddbcd08eed76344863303878b12de1c1e2a04b6.1531953780.git.osandov@xxxxxx
Signed-off-by: Omar Sandoval <osandov@xxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: Bhupesh Sharma <bhsharma@xxxxxxxxxx>
Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx>
Cc: James Morse <james.morse@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/Kconfig | 1 +
fs/proc/kcore.c | 18 ++++++++++++++++--
include/linux/crash_core.h | 2 ++
kernel/crash_core.c | 4 ++--
4 files changed, 21 insertions(+), 4 deletions(-)
diff -puN fs/proc/Kconfig~proc-kcore-add-vmcoreinfo-note-to-proc-kcore fs/proc/Kconfig
--- a/fs/proc/Kconfig~proc-kcore-add-vmcoreinfo-note-to-proc-kcore
+++ a/fs/proc/Kconfig
@@ -31,6 +31,7 @@ config PROC_FS
config PROC_KCORE
bool "/proc/kcore support" if !ARM
depends on PROC_FS && MMU
+ select CRASH_CORE
help
Provides a virtual ELF core file of the live kernel. This can
be read with gdb and other ELF tools. No modifications can be
diff -puN fs/proc/kcore.c~proc-kcore-add-vmcoreinfo-note-to-proc-kcore fs/proc/kcore.c
--- a/fs/proc/kcore.c~proc-kcore-add-vmcoreinfo-note-to-proc-kcore
+++ a/fs/proc/kcore.c
@@ -10,6 +10,7 @@
* Safe accesses to vmalloc/direct-mapped discontiguous areas, Kanoj Sarcar <kanoj@xxxxxxx>
*/
+#include <linux/crash_core.h>
#include <linux/mm.h>
#include <linux/proc_fs.h>
#include <linux/kcore.h>
@@ -81,10 +82,13 @@ static size_t get_kcore_size(int *nphdr,
}
*phdrs_len = *nphdr * sizeof(struct elf_phdr);
- *notes_len = (3 * (sizeof(struct elf_note) + ALIGN(sizeof(CORE_STR), 4)) +
+ *notes_len = (4 * sizeof(struct elf_note) +
+ 3 * ALIGN(sizeof(CORE_STR), 4) +
+ VMCOREINFO_NOTE_NAME_BYTES +
ALIGN(sizeof(struct elf_prstatus), 4) +
ALIGN(sizeof(struct elf_prpsinfo), 4) +
- ALIGN(arch_task_struct_size, 4));
+ ALIGN(arch_task_struct_size, 4) +
+ ALIGN(vmcoreinfo_size, 4));
*data_offset = PAGE_ALIGN(sizeof(struct elfhdr) + *phdrs_len +
*notes_len);
return *data_offset + size;
@@ -406,6 +410,16 @@ read_kcore(struct file *file, char __use
sizeof(prpsinfo));
append_kcore_note(notes, &i, CORE_STR, NT_TASKSTRUCT, current,
arch_task_struct_size);
+ /*
+ * vmcoreinfo_size is mostly constant after init time, but it
+ * can be changed by crash_save_vmcoreinfo(). Racing here with a
+ * panic on another CPU before the machine goes down is insanely
+ * unlikely, but it's better to not leave potential buffer
+ * overflows lying around, regardless.
+ */
+ append_kcore_note(notes, &i, VMCOREINFO_NOTE_NAME, 0,
+ vmcoreinfo_data,
+ min(vmcoreinfo_size, notes_len - i));
tsz = min_t(size_t, buflen, notes_offset + notes_len - *fpos);
if (copy_to_user(buffer, notes + *fpos - notes_offset, tsz)) {
diff -puN include/linux/crash_core.h~proc-kcore-add-vmcoreinfo-note-to-proc-kcore include/linux/crash_core.h
--- a/include/linux/crash_core.h~proc-kcore-add-vmcoreinfo-note-to-proc-kcore
+++ a/include/linux/crash_core.h
@@ -60,6 +60,8 @@ phys_addr_t paddr_vmcoreinfo_note(void);
#define VMCOREINFO_CONFIG(name) \
vmcoreinfo_append_str("CONFIG_%s=y\n", #name)
+extern unsigned char *vmcoreinfo_data;
+extern size_t vmcoreinfo_size;
extern u32 *vmcoreinfo_note;
Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
diff -puN kernel/crash_core.c~proc-kcore-add-vmcoreinfo-note-to-proc-kcore kernel/crash_core.c
--- a/kernel/crash_core.c~proc-kcore-add-vmcoreinfo-note-to-proc-kcore
+++ a/kernel/crash_core.c
@@ -14,8 +14,8 @@
#include <asm/sections.h>
/* vmcoreinfo stuff */
-static unsigned char *vmcoreinfo_data;
-static size_t vmcoreinfo_size;
+unsigned char *vmcoreinfo_data;
+size_t vmcoreinfo_size;
u32 *vmcoreinfo_note;
/* trusted vmcoreinfo, e.g. we can make a copy in the crash memory */
_
Patches currently in -mm which might be from osandov@xxxxxx are
proc-kcore-dont-grab-lock-for-kclist_add.patch
proc-kcore-dont-grab-lock-for-memory-hotplug-notifier.patch
proc-kcore-replace-kclist_lock-rwlock-with-rwsem.patch
proc-kcore-fix-memory-hotplug-vs-multiple-opens-race.patch
proc-kcore-hold-lock-during-read.patch
proc-kcore-clean-up-elf-header-generation.patch
proc-kcore-optimize-multiple-page-reads.patch
proc-kcore-add-vmcoreinfo-note-to-proc-kcore.patch
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