mirror of
https://github.com/torvalds/linux.git
synced 2024-11-24 05:02:12 +00:00
Merge branch 'x86-kdump-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 kdump update from Ingo Molnar: "Add the AMD SME mask to the vmcoreinfo, and also document our vmcoreinfo fields" * 'x86-kdump-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: kdump: Document kernel data exported in the vmcoreinfo note x86/kdump: Export the SME mask to vmcoreinfo
This commit is contained in:
Linus Torvalds
commit
d2cb698f68
495
Documentation/kdump/vmcoreinfo.txt
Normal file
495
Documentation/kdump/vmcoreinfo.txt
Normal file
@ -0,0 +1,495 @@
|
||||
================================================================
|
||||
VMCOREINFO
|
||||
================================================================
|
||||
|
||||
===========
|
||||
What is it?
|
||||
===========
|
||||
|
||||
VMCOREINFO is a special ELF note section. It contains various
|
||||
information from the kernel like structure size, page size, symbol
|
||||
values, field offsets, etc. These data are packed into an ELF note
|
||||
section and used by user-space tools like crash and makedumpfile to
|
||||
analyze a kernel's memory layout.
|
||||
|
||||
================
|
||||
Common variables
|
||||
================
|
||||
|
||||
init_uts_ns.name.release
|
||||
------------------------
|
||||
|
||||
The version of the Linux kernel. Used to find the corresponding source
|
||||
code from which the kernel has been built. For example, crash uses it to
|
||||
find the corresponding vmlinux in order to process vmcore.
|
||||
|
||||
PAGE_SIZE
|
||||
---------
|
||||
|
||||
The size of a page. It is the smallest unit of data used by the memory
|
||||
management facilities. It is usually 4096 bytes of size and a page is
|
||||
aligned on 4096 bytes. Used for computing page addresses.
|
||||
|
||||
init_uts_ns
|
||||
-----------
|
||||
|
||||
The UTS namespace which is used to isolate two specific elements of the
|
||||
system that relate to the uname(2) system call. It is named after the
|
||||
data structure used to store information returned by the uname(2) system
|
||||
call.
|
||||
|
||||
User-space tools can get the kernel name, host name, kernel release
|
||||
number, kernel version, architecture name and OS type from it.
|
||||
|
||||
node_online_map
|
||||
---------------
|
||||
|
||||
An array node_states[N_ONLINE] which represents the set of online nodes
|
||||
in a system, one bit position per node number. Used to keep track of
|
||||
which nodes are in the system and online.
|
||||
|
||||
swapper_pg_dir
|
||||
-------------
|
||||
|
||||
The global page directory pointer of the kernel. Used to translate
|
||||
virtual to physical addresses.
|
||||
|
||||
_stext
|
||||
------
|
||||
|
||||
Defines the beginning of the text section. In general, _stext indicates
|
||||
the kernel start address. Used to convert a virtual address from the
|
||||
direct kernel map to a physical address.
|
||||
|
||||
vmap_area_list
|
||||
--------------
|
||||
|
||||
Stores the virtual area list. makedumpfile gets the vmalloc start value
|
||||
from this variable and its value is necessary for vmalloc translation.
|
||||
|
||||
mem_map
|
||||
-------
|
||||
|
||||
Physical addresses are translated to struct pages by treating them as
|
||||
an index into the mem_map array. Right-shifting a physical address
|
||||
PAGE_SHIFT bits converts it into a page frame number which is an index
|
||||
into that mem_map array.
|
||||
|
||||
Used to map an address to the corresponding struct page.
|
||||
|
||||
contig_page_data
|
||||
----------------
|
||||
|
||||
Makedumpfile gets the pglist_data structure from this symbol, which is
|
||||
used to describe the memory layout.
|
||||
|
||||
User-space tools use this to exclude free pages when dumping memory.
|
||||
|
||||
mem_section|(mem_section, NR_SECTION_ROOTS)|(mem_section, section_mem_map)
|
||||
--------------------------------------------------------------------------
|
||||
|
||||
The address of the mem_section array, its length, structure size, and
|
||||
the section_mem_map offset.
|
||||
|
||||
It exists in the sparse memory mapping model, and it is also somewhat
|
||||
similar to the mem_map variable, both of them are used to translate an
|
||||
address.
|
||||
|
||||
page
|
||||
----
|
||||
|
||||
The size of a page structure. struct page is an important data structure
|
||||
and it is widely used to compute contiguous memory.
|
||||
|
||||
pglist_data
|
||||
-----------
|
||||
|
||||
The size of a pglist_data structure. This value is used to check if the
|
||||
pglist_data structure is valid. It is also used for checking the memory
|
||||
type.
|
||||
|
||||
zone
|
||||
----
|
||||
|
||||
The size of a zone structure. This value is used to check if the zone
|
||||
structure has been found. It is also used for excluding free pages.
|
||||
|
||||
free_area
|
||||
---------
|
||||
|
||||
The size of a free_area structure. It indicates whether the free_area
|
||||
structure is valid or not. Useful when excluding free pages.
|
||||
|
||||
list_head
|
||||
---------
|
||||
|
||||
The size of a list_head structure. Used when iterating lists in a
|
||||
post-mortem analysis session.
|
||||
|
||||
nodemask_t
|
||||
----------
|
||||
|
||||
The size of a nodemask_t type. Used to compute the number of online
|
||||
nodes.
|
||||
|
||||
(page, flags|_refcount|mapping|lru|_mapcount|private|compound_dtor|
|
||||
compound_order|compound_head)
|
||||
-------------------------------------------------------------------
|
||||
|
||||
User-space tools compute their values based on the offset of these
|
||||
variables. The variables are used when excluding unnecessary pages.
|
||||
|
||||
(pglist_data, node_zones|nr_zones|node_mem_map|node_start_pfn|node_
|
||||
spanned_pages|node_id)
|
||||
-------------------------------------------------------------------
|
||||
|
||||
On NUMA machines, each NUMA node has a pg_data_t to describe its memory
|
||||
layout. On UMA machines there is a single pglist_data which describes the
|
||||
whole memory.
|
||||
|
||||
These values are used to check the memory type and to compute the
|
||||
virtual address for memory map.
|
||||
|
||||
(zone, free_area|vm_stat|spanned_pages)
|
||||
---------------------------------------
|
||||
|
||||
Each node is divided into a number of blocks called zones which
|
||||
represent ranges within memory. A zone is described by a structure zone.
|
||||
|
||||
User-space tools compute required values based on the offset of these
|
||||
variables.
|
||||
|
||||
(free_area, free_list)
|
||||
----------------------
|
||||
|
||||
Offset of the free_list's member. This value is used to compute the number
|
||||
of free pages.
|
||||
|
||||
Each zone has a free_area structure array called free_area[MAX_ORDER].
|
||||
The free_list represents a linked list of free page blocks.
|
||||
|
||||
(list_head, next|prev)
|
||||
----------------------
|
||||
|
||||
Offsets of the list_head's members. list_head is used to define a
|
||||
circular linked list. User-space tools need these in order to traverse
|
||||
lists.
|
||||
|
||||
(vmap_area, va_start|list)
|
||||
--------------------------
|
||||
|
||||
Offsets of the vmap_area's members. They carry vmalloc-specific
|
||||
information. Makedumpfile gets the start address of the vmalloc region
|
||||
from this.
|
||||
|
||||
(zone.free_area, MAX_ORDER)
|
||||
---------------------------
|
||||
|
||||
Free areas descriptor. User-space tools use this value to iterate the
|
||||
free_area ranges. MAX_ORDER is used by the zone buddy allocator.
|
||||
|
||||
log_first_idx
|
||||
-------------
|
||||
|
||||
Index of the first record stored in the buffer log_buf. Used by
|
||||
user-space tools to read the strings in the log_buf.
|
||||
|
||||
log_buf
|
||||
-------
|
||||
|
||||
Console output is written to the ring buffer log_buf at index
|
||||
log_first_idx. Used to get the kernel log.
|
||||
|
||||
log_buf_len
|
||||
-----------
|
||||
|
||||
log_buf's length.
|
||||
|
||||
clear_idx
|
||||
---------
|
||||
|
||||
The index that the next printk() record to read after the last clear
|
||||
command. It indicates the first record after the last SYSLOG_ACTION
|
||||
_CLEAR, like issued by 'dmesg -c'. Used by user-space tools to dump
|
||||
the dmesg log.
|
||||
|
||||
log_next_idx
|
||||
------------
|
||||
|
||||
The index of the next record to store in the buffer log_buf. Used to
|
||||
compute the index of the current buffer position.
|
||||
|
||||
printk_log
|
||||
----------
|
||||
|
||||
The size of a structure printk_log. Used to compute the size of
|
||||
messages, and extract dmesg log. It encapsulates header information for
|
||||
log_buf, such as timestamp, syslog level, etc.
|
||||
|
||||
(printk_log, ts_nsec|len|text_len|dict_len)
|
||||
-------------------------------------------
|
||||
|
||||
It represents field offsets in struct printk_log. User space tools
|
||||
parse it and check whether the values of printk_log's members have been
|
||||
changed.
|
||||
|
||||
(free_area.free_list, MIGRATE_TYPES)
|
||||
------------------------------------
|
||||
|
||||
The number of migrate types for pages. The free_list is described by the
|
||||
array. Used by tools to compute the number of free pages.
|
||||
|
||||
NR_FREE_PAGES
|
||||
-------------
|
||||
|
||||
On linux-2.6.21 or later, the number of free pages is in
|
||||
vm_stat[NR_FREE_PAGES]. Used to get the number of free pages.
|
||||
|
||||
PG_lru|PG_private|PG_swapcache|PG_swapbacked|PG_slab|PG_hwpoision
|
||||
|PG_head_mask|PAGE_BUDDY_MAPCOUNT_VALUE(~PG_buddy)
|
||||
|PAGE_OFFLINE_MAPCOUNT_VALUE(~PG_offline)
|
||||
-----------------------------------------------------------------
|
||||
|
||||
Page attributes. These flags are used to filter various unnecessary for
|
||||
dumping pages.
|
||||
|
||||
HUGETLB_PAGE_DTOR
|
||||
-----------------
|
||||
|
||||
The HUGETLB_PAGE_DTOR flag denotes hugetlbfs pages. Makedumpfile
|
||||
excludes these pages.
|
||||
|
||||
======
|
||||
x86_64
|
||||
======
|
||||
|
||||
phys_base
|
||||
---------
|
||||
|
||||
Used to convert the virtual address of an exported kernel symbol to its
|
||||
corresponding physical address.
|
||||
|
||||
init_top_pgt
|
||||
------------
|
||||
|
||||
Used to walk through the whole page table and convert virtual addresses
|
||||
to physical addresses. The init_top_pgt is somewhat similar to
|
||||
swapper_pg_dir, but it is only used in x86_64.
|
||||
|
||||
pgtable_l5_enabled
|
||||
------------------
|
||||
|
||||
User-space tools need to know whether the crash kernel was in 5-level
|
||||
paging mode.
|
||||
|
||||
node_data
|
||||
---------
|
||||
|
||||
This is a struct pglist_data array and stores all NUMA nodes
|
||||
information. Makedumpfile gets the pglist_data structure from it.
|
||||
|
||||
(node_data, MAX_NUMNODES)
|
||||
-------------------------
|
||||
|
||||
The maximum number of nodes in system.
|
||||
|
||||
KERNELOFFSET
|
||||
------------
|
||||
|
||||
The kernel randomization offset. Used to compute the page offset. If
|
||||
KASLR is disabled, this value is zero.
|
||||
|
||||
KERNEL_IMAGE_SIZE
|
||||
-----------------
|
||||
|
||||
Currently unused by Makedumpfile. Used to compute the module virtual
|
||||
address by Crash.
|
||||
|
||||
sme_mask
|
||||
--------
|
||||
|
||||
AMD-specific with SME support: it indicates the secure memory encryption
|
||||
mask. Makedumpfile tools need to know whether the crash kernel was
|
||||
encrypted. If SME is enabled in the first kernel, the crash kernel's
|
||||
page table entries (pgd/pud/pmd/pte) contain the memory encryption
|
||||
mask. This is used to remove the SME mask and obtain the true physical
|
||||
address.
|
||||
|
||||
Currently, sme_mask stores the value of the C-bit position. If needed,
|
||||
additional SME-relevant info can be placed in that variable.
|
||||
|
||||
For example:
|
||||
[ misc ][ enc bit ][ other misc SME info ]
|
||||
0000_0000_0000_0000_1000_0000_0000_0000_0000_0000_..._0000
|
||||
63 59 55 51 47 43 39 35 31 27 ... 3
|
||||
|
||||
======
|
||||
x86_32
|
||||
======
|
||||
|
||||
X86_PAE
|
||||
-------
|
||||
|
||||
Denotes whether physical address extensions are enabled. It has the cost
|
||||
of a higher page table lookup overhead, and also consumes more page
|
||||
table space per process. Used to check whether PAE was enabled in the
|
||||
crash kernel when converting virtual addresses to physical addresses.
|
||||
|
||||
====
|
||||
ia64
|
||||
====
|
||||
|
||||
pgdat_list|(pgdat_list, MAX_NUMNODES)
|
||||
-------------------------------------
|
||||
|
||||
pg_data_t array storing all NUMA nodes information. MAX_NUMNODES
|
||||
indicates the number of the nodes.
|
||||
|
||||
node_memblk|(node_memblk, NR_NODE_MEMBLKS)
|
||||
------------------------------------------
|
||||
|
||||
List of node memory chunks. Filled when parsing the SRAT table to obtain
|
||||
information about memory nodes. NR_NODE_MEMBLKS indicates the number of
|
||||
node memory chunks.
|
||||
|
||||
These values are used to compute the number of nodes the crashed kernel used.
|
||||
|
||||
node_memblk_s|(node_memblk_s, start_paddr)|(node_memblk_s, size)
|
||||
----------------------------------------------------------------
|
||||
|
||||
The size of a struct node_memblk_s and the offsets of the
|
||||
node_memblk_s's members. Used to compute the number of nodes.
|
||||
|
||||
PGTABLE_3|PGTABLE_4
|
||||
-------------------
|
||||
|
||||
User-space tools need to know whether the crash kernel was in 3-level or
|
||||
4-level paging mode. Used to distinguish the page table.
|
||||
|
||||
=====
|
||||
ARM64
|
||||
=====
|
||||
|
||||
VA_BITS
|
||||
-------
|
||||
|
||||
The maximum number of bits for virtual addresses. Used to compute the
|
||||
virtual memory ranges.
|
||||
|
||||
kimage_voffset
|
||||
--------------
|
||||
|
||||
The offset between the kernel virtual and physical mappings. Used to
|
||||
translate virtual to physical addresses.
|
||||
|
||||
PHYS_OFFSET
|
||||
-----------
|
||||
|
||||
Indicates the physical address of the start of memory. Similar to
|
||||
kimage_voffset, which is used to translate virtual to physical
|
||||
addresses.
|
||||
|
||||
KERNELOFFSET
|
||||
------------
|
||||
|
||||
The kernel randomization offset. Used to compute the page offset. If
|
||||
KASLR is disabled, this value is zero.
|
||||
|
||||
====
|
||||
arm
|
||||
====
|
||||
|
||||
ARM_LPAE
|
||||
--------
|
||||
|
||||
It indicates whether the crash kernel supports large physical address
|
||||
extensions. Used to translate virtual to physical addresses.
|
||||
|
||||
====
|
||||
s390
|
||||
====
|
||||
|
||||
lowcore_ptr
|
||||
----------
|
||||
|
||||
An array with a pointer to the lowcore of every CPU. Used to print the
|
||||
psw and all registers information.
|
||||
|
||||
high_memory
|
||||
-----------
|
||||
|
||||
Used to get the vmalloc_start address from the high_memory symbol.
|
||||
|
||||
(lowcore_ptr, NR_CPUS)
|
||||
----------------------
|
||||
|
||||
The maximum number of CPUs.
|
||||
|
||||
=======
|
||||
powerpc
|
||||
=======
|
||||
|
||||
|
||||
node_data|(node_data, MAX_NUMNODES)
|
||||
-----------------------------------
|
||||
|
||||
See above.
|
||||
|
||||
contig_page_data
|
||||
----------------
|
||||
|
||||
See above.
|
||||
|
||||
vmemmap_list
|
||||
------------
|
||||
|
||||
The vmemmap_list maintains the entire vmemmap physical mapping. Used
|
||||
to get vmemmap list count and populated vmemmap regions info. If the
|
||||
vmemmap address translation information is stored in the crash kernel,
|
||||
it is used to translate vmemmap kernel virtual addresses.
|
||||
|
||||
mmu_vmemmap_psize
|
||||
-----------------
|
||||
|
||||
The size of a page. Used to translate virtual to physical addresses.
|
||||
|
||||
mmu_psize_defs
|
||||
--------------
|
||||
|
||||
Page size definitions, i.e. 4k, 64k, or 16M.
|
||||
|
||||
Used to make vtop translations.
|
||||
|
||||
vmemmap_backing|(vmemmap_backing, list)|(vmemmap_backing, phys)|
|
||||
(vmemmap_backing, virt_addr)
|
||||
----------------------------------------------------------------
|
||||
|
||||
The vmemmap virtual address space management does not have a traditional
|
||||
page table to track which virtual struct pages are backed by a physical
|
||||
mapping. The virtual to physical mappings are tracked in a simple linked
|
||||
list format.
|
||||
|
||||
User-space tools need to know the offset of list, phys and virt_addr
|
||||
when computing the count of vmemmap regions.
|
||||
|
||||
mmu_psize_def|(mmu_psize_def, shift)
|
||||
------------------------------------
|
||||
|
||||
The size of a struct mmu_psize_def and the offset of mmu_psize_def's
|
||||
member.
|
||||
|
||||
Used in vtop translations.
|
||||
|
||||
==
|
||||
sh
|
||||
==
|
||||
|
||||
node_data|(node_data, MAX_NUMNODES)
|
||||
-----------------------------------
|
||||
|
||||
See above.
|
||||
|
||||
X2TLB
|
||||
-----
|
||||
|
||||
Indicates whether the crashed kernel enabled SH extended mode.
|
||||
@ -352,6 +352,8 @@ void machine_kexec(struct kimage *image)
|
||||
|
||||
void arch_crash_save_vmcoreinfo(void)
|
||||
{
|
||||
u64 sme_mask = sme_me_mask;
|
||||
|
||||
VMCOREINFO_NUMBER(phys_base);
|
||||
VMCOREINFO_SYMBOL(init_top_pgt);
|
||||
vmcoreinfo_append_str("NUMBER(pgtable_l5_enabled)=%d\n",
|
||||
@ -364,6 +366,7 @@ void arch_crash_save_vmcoreinfo(void)
|
||||
vmcoreinfo_append_str("KERNELOFFSET=%lx\n",
|
||||
kaslr_offset());
|
||||
VMCOREINFO_NUMBER(KERNEL_IMAGE_SIZE);
|
||||
VMCOREINFO_NUMBER(sme_mask);
|
||||
}
|
||||
|
||||
/* arch-dependent functionality related to kexec file-based syscall */
|
||||
|
||||
Loading…
Reference in New Issue
Block a user