Commit 23c85094 authored by Omar Sandoval's avatar Omar Sandoval Committed by Linus Torvalds
Browse files

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@fb.com


Signed-off-by: default avatarOmar Sandoval <osandov@fb.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent eff4345e

fs/proc/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -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

fs/proc/kcore.c

+16 −2
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
 *	Safe accesses to vmalloc/direct-mapped discontiguous areas, Kanoj Sarcar <kanoj@sgi.com>

 */



#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, size_t *phdrs_len, size_t *notes_len, 
	}



	*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 __user *buffer, size_t buflen, loff_t *fpos) 
				  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)) {

include/linux/crash_core.h

+2 −0
Original line number Diff line number Diff line
@@ -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,

kernel/crash_core.c

+2 −2
Original line number Diff line number Diff line
@@ -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 */

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