iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
linux/Documentation/admin-guide/kdump/vmcoreinfo.rst
Linus Torvalds b96a3e9142 - Some swap cleanups from Ma Wupeng ("fix WARN_ON in add_to_avail_list") 
- Peter Xu has a series (mm/gup: Unify hugetlb, speed up thp") which
   reduces the special-case code for handling hugetlb pages in GUP.  It
   also speeds up GUP handling of transparent hugepages.
 
 - Peng Zhang provides some maple tree speedups ("Optimize the fast path
   of mas_store()").
 
 - Sergey Senozhatsky has improved te performance of zsmalloc during
   compaction (zsmalloc: small compaction improvements").
 
 - Domenico Cerasuolo has developed additional selftest code for zswap
   ("selftests: cgroup: add zswap test program").
 
 - xu xin has doe some work on KSM's handling of zero pages.  These
   changes are mainly to enable the user to better understand the
   effectiveness of KSM's treatment of zero pages ("ksm: support tracking
   KSM-placed zero-pages").
 
 - Jeff Xu has fixes the behaviour of memfd's
   MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED sysctl ("mm/memfd: fix sysctl
   MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED").
 
 - David Howells has fixed an fscache optimization ("mm, netfs, fscache:
   Stop read optimisation when folio removed from pagecache").
 
 - Axel Rasmussen has given userfaultfd the ability to simulate memory
   poisoning ("add UFFDIO_POISON to simulate memory poisoning with UFFD").
 
 - Miaohe Lin has contributed some routine maintenance work on the
   memory-failure code ("mm: memory-failure: remove unneeded PageHuge()
   check").
 
 - Peng Zhang has contributed some maintenance work on the maple tree
   code ("Improve the validation for maple tree and some cleanup").
 
 - Hugh Dickins has optimized the collapsing of shmem or file pages into
   THPs ("mm: free retracted page table by RCU").
 
 - Jiaqi Yan has a patch series which permits us to use the healthy
   subpages within a hardware poisoned huge page for general purposes
   ("Improve hugetlbfs read on HWPOISON hugepages").
 
 - Kemeng Shi has done some maintenance work on the pagetable-check code
   ("Remove unused parameters in page_table_check").
 
 - More folioification work from Matthew Wilcox ("More filesystem folio
   conversions for 6.6"), ("Followup folio conversions for zswap").  And
   from ZhangPeng ("Convert several functions in page_io.c to use a
   folio").
 
 - page_ext cleanups from Kemeng Shi ("minor cleanups for page_ext").
 
 - Baoquan He has converted some architectures to use the GENERIC_IOREMAP
   ioremap()/iounmap() code ("mm: ioremap: Convert architectures to take
   GENERIC_IOREMAP way").
 
 - Anshuman Khandual has optimized arm64 tlb shootdown ("arm64: support
   batched/deferred tlb shootdown during page reclamation/migration").
 
 - Better maple tree lockdep checking from Liam Howlett ("More strict
   maple tree lockdep").  Liam also developed some efficiency improvements
   ("Reduce preallocations for maple tree").
 
 - Cleanup and optimization to the secondary IOMMU TLB invalidation, from
   Alistair Popple ("Invalidate secondary IOMMU TLB on permission
   upgrade").
 
 - Ryan Roberts fixes some arm64 MM selftest issues ("selftests/mm fixes
   for arm64").
 
 - Kemeng Shi provides some maintenance work on the compaction code ("Two
   minor cleanups for compaction").
 
 - Some reduction in mmap_lock pressure from Matthew Wilcox ("Handle most
   file-backed faults under the VMA lock").
 
 - Aneesh Kumar contributes code to use the vmemmap optimization for DAX
   on ppc64, under some circumstances ("Add support for DAX vmemmap
   optimization for ppc64").
 
 - page-ext cleanups from Kemeng Shi ("add page_ext_data to get client
   data in page_ext"), ("minor cleanups to page_ext header").
 
 - Some zswap cleanups from Johannes Weiner ("mm: zswap: three
   cleanups").
 
 - kmsan cleanups from ZhangPeng ("minor cleanups for kmsan").
 
 - VMA handling cleanups from Kefeng Wang ("mm: convert to
   vma_is_initial_heap/stack()").
 
 - DAMON feature work from SeongJae Park ("mm/damon/sysfs-schemes:
   implement DAMOS tried total bytes file"), ("Extend DAMOS filters for
   address ranges and DAMON monitoring targets").
 
 - Compaction work from Kemeng Shi ("Fixes and cleanups to compaction").
 
 - Liam Howlett has improved the maple tree node replacement code
   ("maple_tree: Change replacement strategy").
 
 - ZhangPeng has a general code cleanup - use the K() macro more widely
   ("cleanup with helper macro K()").
 
 - Aneesh Kumar brings memmap-on-memory to ppc64 ("Add support for memmap
   on memory feature on ppc64").
 
 - pagealloc cleanups from Kemeng Shi ("Two minor cleanups for pcp list
   in page_alloc"), ("Two minor cleanups for get pageblock migratetype").
 
 - Vishal Moola introduces a memory descriptor for page table tracking,
   "struct ptdesc" ("Split ptdesc from struct page").
 
 - memfd selftest maintenance work from Aleksa Sarai ("memfd: cleanups
   for vm.memfd_noexec").
 
 - MM include file rationalization from Hugh Dickins ("arch: include
   asm/cacheflush.h in asm/hugetlb.h").
 
 - THP debug output fixes from Hugh Dickins ("mm,thp: fix sloppy text
   output").
 
 - kmemleak improvements from Xiaolei Wang ("mm/kmemleak: use
   object_cache instead of kmemleak_initialized").
 
 - More folio-related cleanups from Matthew Wilcox ("Remove _folio_dtor
   and _folio_order").
 
 - A VMA locking scalability improvement from Suren Baghdasaryan
   ("Per-VMA lock support for swap and userfaults").
 
 - pagetable handling cleanups from Matthew Wilcox ("New page table range
   API").
 
 - A batch of swap/thp cleanups from David Hildenbrand ("mm/swap: stop
   using page->private on tail pages for THP_SWAP + cleanups").
 
 - Cleanups and speedups to the hugetlb fault handling from Matthew
   Wilcox ("Change calling convention for ->huge_fault").
 
 - Matthew Wilcox has also done some maintenance work on the MM subsystem
   documentation ("Improve mm documentation").
 -----BEGIN PGP SIGNATURE-----
 
 iHUEABYIAB0WIQTTMBEPP41GrTpTJgfdBJ7gKXxAjgUCZO1JUQAKCRDdBJ7gKXxA
 jrMwAP47r/fS8vAVT3zp/7fXmxaJYTK27CTAM881Gw1SDhFM/wEAv8o84mDenCg6
 Nfio7afS1ncD+hPYT8947UnLxTgn+ww=
 =Afws
 -----END PGP SIGNATURE-----

Merge tag 'mm-stable-2023-08-28-18-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - Some swap cleanups from Ma Wupeng ("fix WARN_ON in
   add_to_avail_list")

 - Peter Xu has a series (mm/gup: Unify hugetlb, speed up thp") which
   reduces the special-case code for handling hugetlb pages in GUP. It
   also speeds up GUP handling of transparent hugepages.

 - Peng Zhang provides some maple tree speedups ("Optimize the fast path
   of mas_store()").

 - Sergey Senozhatsky has improved te performance of zsmalloc during
   compaction (zsmalloc: small compaction improvements").

 - Domenico Cerasuolo has developed additional selftest code for zswap
   ("selftests: cgroup: add zswap test program").

 - xu xin has doe some work on KSM's handling of zero pages. These
   changes are mainly to enable the user to better understand the
   effectiveness of KSM's treatment of zero pages ("ksm: support
   tracking KSM-placed zero-pages").

 - Jeff Xu has fixes the behaviour of memfd's
   MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED sysctl ("mm/memfd: fix sysctl
   MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED").

 - David Howells has fixed an fscache optimization ("mm, netfs, fscache:
   Stop read optimisation when folio removed from pagecache").

 - Axel Rasmussen has given userfaultfd the ability to simulate memory
   poisoning ("add UFFDIO_POISON to simulate memory poisoning with
   UFFD").

 - Miaohe Lin has contributed some routine maintenance work on the
   memory-failure code ("mm: memory-failure: remove unneeded PageHuge()
   check").

 - Peng Zhang has contributed some maintenance work on the maple tree
   code ("Improve the validation for maple tree and some cleanup").

 - Hugh Dickins has optimized the collapsing of shmem or file pages into
   THPs ("mm: free retracted page table by RCU").

 - Jiaqi Yan has a patch series which permits us to use the healthy
   subpages within a hardware poisoned huge page for general purposes
   ("Improve hugetlbfs read on HWPOISON hugepages").

 - Kemeng Shi has done some maintenance work on the pagetable-check code
   ("Remove unused parameters in page_table_check").

 - More folioification work from Matthew Wilcox ("More filesystem folio
   conversions for 6.6"), ("Followup folio conversions for zswap"). And
   from ZhangPeng ("Convert several functions in page_io.c to use a
   folio").

 - page_ext cleanups from Kemeng Shi ("minor cleanups for page_ext").

 - Baoquan He has converted some architectures to use the
   GENERIC_IOREMAP ioremap()/iounmap() code ("mm: ioremap: Convert
   architectures to take GENERIC_IOREMAP way").

 - Anshuman Khandual has optimized arm64 tlb shootdown ("arm64: support
   batched/deferred tlb shootdown during page reclamation/migration").

 - Better maple tree lockdep checking from Liam Howlett ("More strict
   maple tree lockdep"). Liam also developed some efficiency
   improvements ("Reduce preallocations for maple tree").

 - Cleanup and optimization to the secondary IOMMU TLB invalidation,
   from Alistair Popple ("Invalidate secondary IOMMU TLB on permission
   upgrade").

 - Ryan Roberts fixes some arm64 MM selftest issues ("selftests/mm fixes
   for arm64").

 - Kemeng Shi provides some maintenance work on the compaction code
   ("Two minor cleanups for compaction").

 - Some reduction in mmap_lock pressure from Matthew Wilcox ("Handle
   most file-backed faults under the VMA lock").

 - Aneesh Kumar contributes code to use the vmemmap optimization for DAX
   on ppc64, under some circumstances ("Add support for DAX vmemmap
   optimization for ppc64").

 - page-ext cleanups from Kemeng Shi ("add page_ext_data to get client
   data in page_ext"), ("minor cleanups to page_ext header").

 - Some zswap cleanups from Johannes Weiner ("mm: zswap: three
   cleanups").

 - kmsan cleanups from ZhangPeng ("minor cleanups for kmsan").

 - VMA handling cleanups from Kefeng Wang ("mm: convert to
   vma_is_initial_heap/stack()").

 - DAMON feature work from SeongJae Park ("mm/damon/sysfs-schemes:
   implement DAMOS tried total bytes file"), ("Extend DAMOS filters for
   address ranges and DAMON monitoring targets").

 - Compaction work from Kemeng Shi ("Fixes and cleanups to compaction").

 - Liam Howlett has improved the maple tree node replacement code
   ("maple_tree: Change replacement strategy").

 - ZhangPeng has a general code cleanup - use the K() macro more widely
   ("cleanup with helper macro K()").

 - Aneesh Kumar brings memmap-on-memory to ppc64 ("Add support for
   memmap on memory feature on ppc64").

 - pagealloc cleanups from Kemeng Shi ("Two minor cleanups for pcp list
   in page_alloc"), ("Two minor cleanups for get pageblock
   migratetype").

 - Vishal Moola introduces a memory descriptor for page table tracking,
   "struct ptdesc" ("Split ptdesc from struct page").

 - memfd selftest maintenance work from Aleksa Sarai ("memfd: cleanups
   for vm.memfd_noexec").

 - MM include file rationalization from Hugh Dickins ("arch: include
   asm/cacheflush.h in asm/hugetlb.h").

 - THP debug output fixes from Hugh Dickins ("mm,thp: fix sloppy text
   output").

 - kmemleak improvements from Xiaolei Wang ("mm/kmemleak: use
   object_cache instead of kmemleak_initialized").

 - More folio-related cleanups from Matthew Wilcox ("Remove _folio_dtor
   and _folio_order").

 - A VMA locking scalability improvement from Suren Baghdasaryan
   ("Per-VMA lock support for swap and userfaults").

 - pagetable handling cleanups from Matthew Wilcox ("New page table
   range API").

 - A batch of swap/thp cleanups from David Hildenbrand ("mm/swap: stop
   using page->private on tail pages for THP_SWAP + cleanups").

 - Cleanups and speedups to the hugetlb fault handling from Matthew
   Wilcox ("Change calling convention for ->huge_fault").

 - Matthew Wilcox has also done some maintenance work on the MM
   subsystem documentation ("Improve mm documentation").

* tag 'mm-stable-2023-08-28-18-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (489 commits)
  maple_tree: shrink struct maple_tree
  maple_tree: clean up mas_wr_append()
  secretmem: convert page_is_secretmem() to folio_is_secretmem()
  nios2: fix flush_dcache_page() for usage from irq context
  hugetlb: add documentation for vma_kernel_pagesize()
  mm: add orphaned kernel-doc to the rst files.
  mm: fix clean_record_shared_mapping_range kernel-doc
  mm: fix get_mctgt_type() kernel-doc
  mm: fix kernel-doc warning from tlb_flush_rmaps()
  mm: remove enum page_entry_size
  mm: allow ->huge_fault() to be called without the mmap_lock held
  mm: move PMD_ORDER to pgtable.h
  mm: remove checks for pte_index
  memcg: remove duplication detection for mem_cgroup_uncharge_swap
  mm/huge_memory: work on folio->swap instead of page->private when splitting folio
  mm/swap: inline folio_set_swap_entry() and folio_swap_entry()
  mm/swap: use dedicated entry for swap in folio
  mm/swap: stop using page->private on tail pages for THP_SWAP
  selftests/mm: fix WARNING comparing pointer to 0
  selftests: cgroup: fix test_kmem_memcg_deletion kernel mem check
  ...
2023-08-29 14:25:26 -07:00

627 lines
17 KiB
ReStructuredText
Raw Blame History

==========
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.
(uts_namespace, name)
---------------------
Offset of the name's member. Crash Utility and Makedumpfile get
the start address of the init_uts_ns.name from this.
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.
MAX_PHYSMEM_BITS
----------------
Defines the maximum supported physical address space memory.
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_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 + 1].
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 + 1)
-------------------------------
Free areas descriptor. User-space tools use this value to iterate the
free_area ranges. MAX_ORDER is used by the zone buddy allocator.
prb
---
A pointer to the printk ringbuffer (struct printk_ringbuffer). This
may be pointing to the static boot ringbuffer or the dynamically
allocated ringbuffer, depending on when the core dump occurred.
Used by user-space tools to read the active kernel log buffer.
printk_rb_static
----------------
A pointer to the static boot printk ringbuffer. If @prb has a
different value, this is useful for viewing the initial boot messages,
which may have been overwritten in the dynamically allocated
ringbuffer.
clear_seq
---------
The sequence number of the printk() record 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 a subset of the dmesg log.
printk_ringbuffer
-----------------
The size of a printk_ringbuffer structure. This structure contains all
information required for accessing the various components of the
kernel log buffer.
(printk_ringbuffer, desc_ring|text_data_ring|dict_data_ring|fail)
-----------------------------------------------------------------
Offsets for the various components of the printk ringbuffer. Used by
user-space tools to view the kernel log buffer without requiring the
declaration of the structure.
prb_desc_ring
-------------
The size of the prb_desc_ring structure. This structure contains
information about the set of record descriptors.
(prb_desc_ring, count_bits|descs|head_id|tail_id)
-------------------------------------------------
Offsets for the fields describing the set of record descriptors. Used
by user-space tools to be able to traverse the descriptors without
requiring the declaration of the structure.
prb_desc
--------
The size of the prb_desc structure. This structure contains
information about a single record descriptor.
(prb_desc, info|state_var|text_blk_lpos|dict_blk_lpos)
------------------------------------------------------
Offsets for the fields describing a record descriptors. Used by
user-space tools to be able to read descriptors without requiring
the declaration of the structure.
prb_data_blk_lpos
-----------------
The size of the prb_data_blk_lpos structure. This structure contains
information about where the text or dictionary data (data block) is
located within the respective data ring.
(prb_data_blk_lpos, begin|next)
-------------------------------
Offsets for the fields describing the location of a data block. Used
by user-space tools to be able to locate data blocks without
requiring the declaration of the structure.
printk_info
-----------
The size of the printk_info structure. This structure contains all
the meta-data for a record.
(printk_info, seq|ts_nsec|text_len|dict_len|caller_id)
------------------------------------------------------
Offsets for the fields providing the meta-data for a record. Used by
user-space tools to be able to read the information without requiring
the declaration of the structure.
prb_data_ring
-------------
The size of the prb_data_ring structure. This structure contains
information about a set of data blocks.
(prb_data_ring, size_bits|data|head_lpos|tail_lpos)
---------------------------------------------------
Offsets for the fields describing a set of data blocks. Used by
user-space tools to be able to access the data blocks without
requiring the declaration of the structure.
atomic_long_t
-------------
The size of the atomic_long_t structure. Used by user-space tools to
be able to copy the full structure, regardless of its
architecture-specific implementation.
(atomic_long_t, counter)
------------------------
Offset for the long value of an atomic_long_t variable. Used by
user-space tools to access the long value without requiring the
architecture-specific declaration.
(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|PG_hugetlb
-----------------------------------------------------------------------------------------
Page attributes. These flags are used to filter various unnecessary for
dumping pages.
PAGE_BUDDY_MAPCOUNT_VALUE(~PG_buddy)|PAGE_OFFLINE_MAPCOUNT_VALUE(~PG_offline)
-----------------------------------------------------------------------------
More page attributes. These flags are used to filter various unnecessary for
dumping 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.
KERNELPACMASK
-------------
The mask to extract the Pointer Authentication Code from a kernel virtual
address.
TCR_EL1.T1SZ
------------
Indicates the size offset of the memory region addressed by TTBR1_EL1.
The region size is 2^(64-T1SZ) bytes.
TTBR1_EL1 is the table base address register specified by ARMv8-A
architecture which is used to lookup the page-tables for the Virtual
addresses in the higher VA range (refer to ARMv8 ARM document for
more details).
MODULES_VADDR|MODULES_END|VMALLOC_START|VMALLOC_END|VMEMMAP_START|VMEMMAP_END
-----------------------------------------------------------------------------
Used to get the correct ranges:
MODULES_VADDR ~ MODULES_END-1 : Kernel module space.
VMALLOC_START ~ VMALLOC_END-1 : vmalloc() / ioremap() space.
VMEMMAP_START ~ VMEMMAP_END-1 : vmemmap region, used for struct page array.
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.
RISCV64
=======
VA_BITS
-------
The maximum number of bits for virtual addresses. Used to compute the
virtual memory ranges.
PAGE_OFFSET
-----------
Indicates the virtual kernel start address of the direct-mapped RAM region.
phys_ram_base
-------------
Indicates the start physical RAM address.
MODULES_VADDR|MODULES_END|VMALLOC_START|VMALLOC_END|VMEMMAP_START|VMEMMAP_END|KERNEL_LINK_ADDR
----------------------------------------------------------------------------------------------
Used to get the correct ranges:
* MODULES_VADDR ~ MODULES_END : Kernel module space.
* VMALLOC_START ~ VMALLOC_END : vmalloc() / ioremap() space.
* VMEMMAP_START ~ VMEMMAP_END : vmemmap space, used for struct page array.
* KERNEL_LINK_ADDR : start address of Kernel link and BPF
va_kernel_pa_offset
-------------------
Indicates the offset between the kernel virtual and physical mappings.
Used to translate virtual to physical addresses.
Reference in New Issue View Git Blame Copy Permalink