linux.git/scripts/module.lds.S, branch v6.18.21

alloc_tag: remove empty module tag section

2025-07-10T05:42:03+00:00

The empty MOD_CODETAG_SECTIONS() macro added an incomplete .data section
in module linker script, which caused symbol lookup tools like gdb to
misinterpret symbol addresses e.g., __ib_process_cq incorrectly mapping to
unrelated functions like below.

  (gdb) disas __ib_process_cq
  Dump of assembler code for function trace_event_fields_cq_schedule:

Removing the empty section restores proper symbol resolution and layout,
ensuring .data placement behaves as expected.

Link: https://lkml.kernel.org/r/20250610162258.324645-1-cachen@purestorage.com
Fixes: 0db6f8d7820a ("alloc_tag: load module tags into separate contiguous memory")
       22d407b164ff ("lib: add allocation tagging support for memory allocation profiling")
Signed-off-by: Casey Chen 
Reviewed-by: Yuanyuan Zhong 
Acked-by: Suren Baghdasaryan 
Cc: Arnd Bergmann 
Cc: Kent Overstreet 
Cc: Luis Chamberalin 
Cc: Pasha Tatashin 
Signed-off-by: Andrew Morton

kbuild: keep symbols for symbol_get() even with CONFIG_TRIM_UNUSED_KSYMS

2025-02-05T16:08:58+00:00

Linus observed that the symbol_request(utf8_data_table) call fails when
CONFIG_UNICODE=y and CONFIG_TRIM_UNUSED_KSYMS=y.

symbol_get() relies on the symbol data being present in the ksymtab for
symbol lookups. However, EXPORT_SYMBOL_GPL(utf8_data_table) is dropped
due to CONFIG_TRIM_UNUSED_KSYMS, as no module references it in this case.

Probably, this has been broken since commit dbacb0ef670d ("kconfig option
for TRIM_UNUSED_KSYMS").

This commit addresses the issue by leveraging modpost. Symbol names
passed to symbol_get() are recorded in the special .no_trim_symbol
section, which is then parsed by modpost to forcibly keep such symbols.
The .no_trim_symbol section is discarded by the linker scripts, so there
is no impact on the size of the final vmlinux or modules.

This commit cannot resolve the issue for direct calls to __symbol_get()
because the symbol name is not known at compile-time.

Although symbol_get() may eventually be deprecated, this workaround
should be good enough meanwhile.

Reported-by: Linus Torvalds 
Suggested-by: Linus Torvalds 
Signed-off-by: Masahiro Yamada

Merge tag 'modules-6.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/modules/linux

2024-11-27T18:20:50+00:00

Pull modules updates from Luis Chamberlain:

 - The whole caching of module code into huge pages by Mike Rapoport is
   going in through Andrew Morton's tree due to some other code
   dependencies. That's really the biggest highlight for Linux kernel
   modules in this release. With it we share huge pages for modules,
   starting off with x86. Expect to see that soon through Andrew!

 - Helge Deller addressed some lingering low hanging fruit alignment
   enhancements by. It is worth pointing out that from his old patch
   series I dropped his vmlinux.lds.h change at Masahiro's request as he
   would prefer this to be specified in asm code [0].

    [0] https://lore.kernel.org/all/20240129192644.3359978-5-mcgrof@kernel.org/T/#m9efef5e700fbecd28b7afb462c15eed8ba78ef5a

 - Matthew Maurer and Sami Tolvanen have been tag teaming to help get us
   closer to a modversions for Rust. In this cycle we take in quite a
   lot of the refactoring for ELF validation. I expect modversions for
   Rust will be merged by v6.14 as that code is mostly ready now.

 - Adds a new modules selftests: kallsyms which helps us tests
   find_symbol() and the limits of kallsyms on Linux today.

 - We have a realtime mailing list to kernel-ci testing for modules now
   which relies and combines patchwork, kpd and kdevops:

     https://patchwork.kernel.org/project/linux-modules/list/
     https://github.com/linux-kdevops/kdevops/blob/main/docs/kernel-ci/README.md
     https://github.com/linux-kdevops/kdevops/blob/main/docs/kernel-ci/kernel-ci-kpd.md
     https://github.com/linux-kdevops/kdevops/blob/main/docs/kernel-ci/linux-modules-kdevops-ci.md

   If you want to help avoid Linux kernel modules regressions, now its
   simple, just add a new Linux modules sefltests under
   tools/testing/selftests/module/ That is it. All new selftests will be
   used and leveraged automatically by the CI.

* tag 'modules-6.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/modules/linux:
  tests/module/gen_test_kallsyms.sh: use 0 value for variables
  scripts: Remove export_report.pl
  selftests: kallsyms: add MODULE_DESCRIPTION
  selftests: add new kallsyms selftests
  module: Reformat struct for code style
  module: Additional validation in elf_validity_cache_strtab
  module: Factor out elf_validity_cache_strtab
  module: Group section index calculations together
  module: Factor out elf_validity_cache_index_str
  module: Factor out elf_validity_cache_index_sym
  module: Factor out elf_validity_cache_index_mod
  module: Factor out elf_validity_cache_index_info
  module: Factor out elf_validity_cache_secstrings
  module: Factor out elf_validity_cache_sechdrs
  module: Factor out elf_validity_ehdr
  module: Take const arg in validate_section_offset
  modules: Add missing entry for __ex_table
  modules: Ensure 64-bit alignment on __ksymtab_* sections

alloc_tag: load module tags into separate contiguous memory

2024-11-07T22:25:16+00:00

When a module gets unloaded there is a possibility that some of the
allocations it made are still used and therefore the allocation tags
corresponding to these allocations are still referenced.  As such, the
memory for these tags can't be freed.  This is currently handled as an
abnormal situation and module's data section is not being unloaded.  To
handle this situation without keeping module's data in memory, allow
codetags with longer lifespan than the module to be loaded into their own
separate memory.  The in-use memory areas and gaps after module unloading
in this separate memory are tracked using maple trees.  Allocation tags
arrange their separate memory so that it is virtually contiguous and that
will allow simple allocation tag indexing later on in this patchset.  The
size of this virtually contiguous memory is set to store up to 100000
allocation tags.

[surenb@google.com: fix empty codetag module section handling]
  Link: https://lkml.kernel.org/r/20241101000017.3856204-1-surenb@google.com
[akpm@linux-foundation.org: update comment, per Dan]
Link: https://lkml.kernel.org/r/20241023170759.999909-4-surenb@google.com
Signed-off-by: Suren Baghdasaryan 
Reviewed-by: Pasha Tatashin 
Cc: Ard Biesheuvel 
Cc: Arnd Bergmann 
Cc: Borislav Petkov (AMD) 
Cc: Christoph Hellwig 
Cc: Daniel Gomez 
Cc: David Hildenbrand 
Cc: Davidlohr Bueso 
Cc: David Rientjes 
Cc: Dennis Zhou 
Cc: Johannes Weiner 
Cc: John Hubbard 
Cc: Jonathan Corbet 
Cc: Joonsoo Kim 
Cc: Kalesh Singh 
Cc: Kees Cook 
Cc: Kent Overstreet 
Cc: Liam R. Howlett 
Cc: Luis Chamberlain 
Cc: Matthew Wilcox 
Cc: Michal Hocko 
Cc: Mike Rapoport (Microsoft) 
Cc: Minchan Kim 
Cc: Paul E. McKenney 
Cc: Petr Pavlu 
Cc: Roman Gushchin 
Cc: Sami Tolvanen 
Cc: Sourav Panda 
Cc: Steven Rostedt (Google) 
Cc: Thomas Gleixner 
Cc: Thomas Huth 
Cc: Uladzislau Rezki (Sony) 
Cc: Vlastimil Babka 
Cc: Xiongwei Song 
Cc: Yu Zhao 
Cc: Dan Carpenter 
Signed-off-by: Andrew Morton

modules: Add missing entry for __ex_table

2024-10-19T20:40:42+00:00

The entry for __ex_table was missing, which may make __ex_table
become 1- or 2-byte aligned in modules.
Add the entry to ensure it gets 32-bit aligned.

As per unaligned-memory-access [0] "unaligned memory accesses [...]
will not work correctly on certain platforms and will cause performance
problems on others", so fix this.

Signed-off-by: Helge Deller 
[mcgrof: added unaligned-memory-access justification]
Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/core-api/unaligned-memory-access.rst # [0]
Signed-off-by: Luis Chamberlain

modules: Ensure 64-bit alignment on __ksymtab_* sections

2024-10-19T20:35:24+00:00

On 64-bit architectures without CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
(e.g. ppc64, ppc64le, parisc, s390x,...) the __KSYM_REF() macro stores
64-bit pointers into the __ksymtab* sections.
Make sure that those sections will be correctly aligned at module link time,
otherwise unaligned memory accesses may happen at runtime.

As per unaligned-memory-access [0] "unaligned memory accesses [...]
will not work correctly on certain platforms and will cause performance
problems on others", so fix this.

The __kcrctab* sections store 32-bit entities, so use ALIGN(4) for those.

Signed-off-by: Helge Deller 
[mcgrof: added unaligned-memory-access justification]
Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/core-api/unaligned-memory-access.rst # [0]
Signed-off-by: Luis Chamberlain

Merge tag 'mm-stable-2024-05-17-19-19' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2024-05-19T16:21:03+00:00

Pull mm updates from Andrew Morton:
"The usual shower of singleton fixes and minor series all over MM,
documented (hopefully adequately) in the respective changelogs.
Notable series include:

- Lucas Stach has provided some page-mapping cleanup/consolidation/
maintainability work in the series "mm/treewide: Remove pXd_huge()
API".

- In the series "Allow migrate on protnone reference with
MPOL_PREFERRED_MANY policy", Donet Tom has optimized mempolicy's
MPOL_PREFERRED_MANY mode, yielding almost doubled performance in
one test.

- In their series "Memory allocation profiling" Kent Overstreet and
Suren Baghdasaryan have contributed a means of determining (via
/proc/allocinfo) whereabouts in the kernel memory is being
allocated: number of calls and amount of memory.

- Matthew Wilcox has provided the series "Various significant MM
patches" which does a number of rather unrelated things, but in
largely similar code sites.

- In his series "mm: page_alloc: freelist migratetype hygiene"
Johannes Weiner has fixed the page allocator's handling of
migratetype requests, with resulting improvements in compaction
efficiency.

- In the series "make the hugetlb migration strategy consistent"
Baolin Wang has fixed a hugetlb migration issue, which should
improve hugetlb allocation reliability.

- Liu Shixin has hit an I/O meltdown caused by readahead in a
memory-tight memcg. Addressed in the series "Fix I/O high when
memory almost met memcg limit".

- In the series "mm/filemap: optimize folio adding and splitting"
Kairui Song has optimized pagecache insertion, yielding ~10%
performance improvement in one test.

- Baoquan He has cleaned up and consolidated the early zone
initialization code in the series "mm/mm_init.c: refactor
free_area_init_core()".

- Baoquan has also redone some MM initializatio code in the series
"mm/init: minor clean up and improvement".

- MM helper cleanups from Christoph Hellwig in his series "remove
follow_pfn".

- More cleanups from Matthew Wilcox in the series "Various
page->flags cleanups".

- Vlastimil Babka has contributed maintainability improvements in the
series "memcg_kmem hooks refactoring".

- More folio conversions and cleanups in Matthew Wilcox's series:
"Convert huge_zero_page to huge_zero_folio"
"khugepaged folio conversions"
"Remove page_idle and page_young wrappers"
"Use folio APIs in procfs"
"Clean up __folio_put()"
"Some cleanups for memory-failure"
"Remove page_mapping()"
"More folio compat code removal"

- David Hildenbrand chipped in with "fs/proc/task_mmu: convert
hugetlb functions to work on folis".

- Code consolidation and cleanup work related to GUP's handling of
hugetlbs in Peter Xu's series "mm/gup: Unify hugetlb, part 2".

- Rick Edgecombe has developed some fixes to stack guard gaps in the
series "Cover a guard gap corner case".

- Jinjiang Tu has fixed KSM's behaviour after a fork+exec in the
series "mm/ksm: fix ksm exec support for prctl".

- Baolin Wang has implemented NUMA balancing for multi-size THPs.
This is a simple first-cut implementation for now. The series is
"support multi-size THP numa balancing".

- Cleanups to vma handling helper functions from Matthew Wilcox in
the series "Unify vma_address and vma_pgoff_address".

- Some selftests maintenance work from Dev Jain in the series
"selftests/mm: mremap_test: Optimizations and style fixes".

- Improvements to the swapping of multi-size THPs from Ryan Roberts
in the series "Swap-out mTHP without splitting".

- Kefeng Wang has significantly optimized the handling of arm64's
permission page faults in the series
"arch/mm/fault: accelerate pagefault when badaccess"
"mm: remove arch's private VM_FAULT_BADMAP/BADACCESS"

- GUP cleanups from David Hildenbrand in "mm/gup: consistently call
it GUP-fast".

- hugetlb fault code cleanups from Vishal Moola in "Hugetlb fault
path to use struct vm_fault".

- selftests build fixes from John Hubbard in the series "Fix
selftests/mm build without requiring "make headers"".

- Memory tiering fixes/improvements from Ho-Ren (Jack) Chuang in the
series "Improved Memory Tier Creation for CPUless NUMA Nodes".
Fixes the initialization code so that migration between different
memory types works as intended.

- David Hildenbrand has improved follow_pte() and fixed an errant
driver in the series "mm: follow_pte() improvements and acrn
follow_pte() fixes".

- David also did some cleanup work on large folio mapcounts in his
series "mm: mapcount for large folios + page_mapcount() cleanups".

- Folio conversions in KSM in Alex Shi's series "transfer page to
folio in KSM".

- Barry Song has added some sysfs stats for monitoring multi-size
THP's in the series "mm: add per-order mTHP alloc and swpout
counters".

- Some zswap cleanups from Yosry Ahmed in the series "zswap
same-filled and limit checking cleanups".

- Matthew Wilcox has been looking at buffer_head code and found the
documentation to be lacking. The series is "Improve buffer head
documentation".

- Multi-size THPs get more work, this time from Lance Yang. His
series "mm/madvise: enhance lazyfreeing with mTHP in madvise_free"
optimizes the freeing of these things.

- Kemeng Shi has added more userspace-visible writeback
instrumentation in the series "Improve visibility of writeback".

- Kemeng Shi then sent some maintenance work on top in the series
"Fix and cleanups to page-writeback".

- Matthew Wilcox reduces mmap_lock traffic in the anon vma code in
the series "Improve anon_vma scalability for anon VMAs". Intel's
test bot reported an improbable 3x improvement in one test.

- SeongJae Park adds some DAMON feature work in the series
"mm/damon: add a DAMOS filter type for page granularity access recheck"
"selftests/damon: add DAMOS quota goal test"

- Also some maintenance work in the series
"mm/damon/paddr: simplify page level access re-check for pageout"
"mm/damon: misc fixes and improvements"

- David Hildenbrand has disabled some known-to-fail selftests ni the
series "selftests: mm: cow: flag vmsplice() hugetlb tests as
XFAIL".

- memcg metadata storage optimizations from Shakeel Butt in "memcg:
reduce memory consumption by memcg stats".

- DAX fixes and maintenance work from Vishal Verma in the series
"dax/bus.c: Fixups for dax-bus locking""

* tag 'mm-stable-2024-05-17-19-19' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (426 commits)
memcg, oom: cleanup unused memcg_oom_gfp_mask and memcg_oom_order
selftests/mm: hugetlb_madv_vs_map: avoid test skipping by querying hugepage size at runtime
mm/hugetlb: add missing VM_FAULT_SET_HINDEX in hugetlb_wp
mm/hugetlb: add missing VM_FAULT_SET_HINDEX in hugetlb_fault
selftests: cgroup: add tests to verify the zswap writeback path
mm: memcg: make alloc_mem_cgroup_per_node_info() return bool
mm/damon/core: fix return value from damos_wmark_metric_value
mm: do not update memcg stats for NR_{FILE/SHMEM}_PMDMAPPED
selftests: cgroup: remove redundant enabling of memory controller
Docs/mm/damon/maintainer-profile: allow posting patches based on damon/next tree
Docs/mm/damon/maintainer-profile: change the maintainer's timezone from PST to PT
Docs/mm/damon/design: use a list for supported filters
Docs/admin-guide/mm/damon/usage: fix wrong schemes effective quota update command
Docs/admin-guide/mm/damon/usage: fix wrong example of DAMOS filter matching sysfs file
selftests/damon: classify tests for functionalities and regressions
selftests/damon/_damon_sysfs: use 'is' instead of '==' for 'None'
selftests/damon/_damon_sysfs: find sysfs mount point from /proc/mounts
selftests/damon/_damon_sysfs: check errors from nr_schemes file reads
mm/damon/core: initialize ->esz_bp from damos_quota_init_priv()
selftests/damon: add a test for DAMOS quota goal
...

modules: Drop the .export_symbol section from the final modules

2024-05-14T05:03:26+00:00

Commit ddb5cdbafaaa ("kbuild: generate KSYMTAB entries by modpost")
forget drop the .export_symbol section from the final modules.

Fixes: ddb5cdbafaaa ("kbuild: generate KSYMTAB entries by modpost")
Signed-off-by: Wang Yao 
Signed-off-by: Masahiro Yamada

lib: add allocation tagging support for memory allocation profiling

2024-04-26T03:55:52+00:00

Introduce CONFIG_MEM_ALLOC_PROFILING which provides definitions to easily
instrument memory allocators.  It registers an "alloc_tags" codetag type
with /proc/allocinfo interface to output allocation tag information when
the feature is enabled.

CONFIG_MEM_ALLOC_PROFILING_DEBUG is provided for debugging the memory
allocation profiling instrumentation.

Memory allocation profiling can be enabled or disabled at runtime using
/proc/sys/vm/mem_profiling sysctl when CONFIG_MEM_ALLOC_PROFILING_DEBUG=n.
CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT enables memory allocation
profiling by default.

[surenb@google.com: Documentation/filesystems/proc.rst: fix allocinfo title]
  Link: https://lkml.kernel.org/r/20240326073813.727090-1-surenb@google.com
[surenb@google.com: do limited memory accounting for modules with ARCH_NEEDS_WEAK_PER_CPU]
  Link: https://lkml.kernel.org/r/20240402180933.1663992-2-surenb@google.com
[klarasmodin@gmail.com: explicitly include irqflags.h in alloc_tag.h]
  Link: https://lkml.kernel.org/r/20240407133252.173636-1-klarasmodin@gmail.com
[surenb@google.com: fix alloc_tag_init() to prevent passing NULL to PTR_ERR()]
  Link: https://lkml.kernel.org/r/20240417003349.2520094-1-surenb@google.com
Link: https://lkml.kernel.org/r/20240321163705.3067592-14-surenb@google.com
Signed-off-by: Suren Baghdasaryan 
Co-developed-by: Kent Overstreet 
Signed-off-by: Kent Overstreet 
Signed-off-by: Klara Modin 
Tested-by: Kees Cook 
Cc: Alexander Viro 
Cc: Alex Gaynor 
Cc: Alice Ryhl 
Cc: Andreas Hindborg 
Cc: Benno Lossin 
Cc: "Björn Roy Baron" 
Cc: Boqun Feng 
Cc: Christoph Lameter 
Cc: Dennis Zhou 
Cc: Gary Guo 
Cc: Miguel Ojeda 
Cc: Pasha Tatashin 
Cc: Peter Zijlstra 
Cc: Tejun Heo 
Cc: Vlastimil Babka 
Cc: Wedson Almeida Filho 
Signed-off-by: Andrew Morton

arm64: unwind: add asynchronous unwind tables to kernel and modules

2022-11-09T18:06:35+00:00

Enable asynchronous unwind table generation for both the core kernel as
well as modules, and emit the resulting .eh_frame sections as init code
so we can use the unwind directives for code patching at boot or module
load time.

This will be used by dynamic shadow call stack support, which will rely
on code patching rather than compiler codegen to emit the shadow call
stack push and pop instructions.

Signed-off-by: Ard Biesheuvel 
Reviewed-by: Nick Desaulniers 
Reviewed-by: Sami Tolvanen 
Tested-by: Sami Tolvanen 
Link: https://lore.kernel.org/r/20221027155908.1940624-2-ardb@kernel.org
Signed-off-by: Will Deacon