6f612579be
- Build footprint & performance improvements:
- Reduce memory usage with CONFIG_DEBUG_INFO=y
In the worst case of an allyesconfig+CONFIG_DEBUG_INFO=y kernel, DWARF
creates almost 200 million relocations, ballooning objtool's peak heap
usage to 53GB. These patches reduce that to 25GB.
On a distro-type kernel with kernel IBT enabled, they reduce objtool's
peak heap usage from 4.2GB to 2.8GB.
These changes also improve the runtime significantly.
- Debuggability improvements:
- Add the unwind_debug command-line option, for more extend unwinding
debugging output.
- Limit unreachable warnings to once per function
- Add verbose option for disassembling affected functions
- Include backtrace in verbose mode
- Detect missing __noreturn annotations
- Ignore exc_double_fault() __noreturn warnings
- Remove superfluous global_noreturns entries
- Move noreturn function list to separate file
- Add __kunit_abort() to noreturns
- Unwinder improvements:
- Allow stack operations in UNWIND_HINT_UNDEFINED regions
- drm/vmwgfx: Add unwind hints around RBP clobber
- Cleanups:
- Move the x86 entry thunk restore code into thunk functions
- x86/unwind/orc: Use swap() instead of open coding it
- Remove unnecessary/unused variables
- Fixes for modern stack canary handling
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'objtool-core-2023-06-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool updates from Ingo Molar:
"Build footprint & performance improvements:
- Reduce memory usage with CONFIG_DEBUG_INFO=y
In the worst case of an allyesconfig+CONFIG_DEBUG_INFO=y kernel,
DWARF creates almost 200 million relocations, ballooning objtool's
peak heap usage to 53GB. These patches reduce that to 25GB.
On a distro-type kernel with kernel IBT enabled, they reduce
objtool's peak heap usage from 4.2GB to 2.8GB.
These changes also improve the runtime significantly.
Debuggability improvements:
- Add the unwind_debug command-line option, for more extend unwinding
debugging output
- Limit unreachable warnings to once per function
- Add verbose option for disassembling affected functions
- Include backtrace in verbose mode
- Detect missing __noreturn annotations
- Ignore exc_double_fault() __noreturn warnings
- Remove superfluous global_noreturns entries
- Move noreturn function list to separate file
- Add __kunit_abort() to noreturns
Unwinder improvements:
- Allow stack operations in UNWIND_HINT_UNDEFINED regions
- drm/vmwgfx: Add unwind hints around RBP clobber
Cleanups:
- Move the x86 entry thunk restore code into thunk functions
- x86/unwind/orc: Use swap() instead of open coding it
- Remove unnecessary/unused variables
Fixes for modern stack canary handling"
* tag 'objtool-core-2023-06-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (42 commits)
x86/orc: Make the is_callthunk() definition depend on CONFIG_BPF_JIT=y
objtool: Skip reading DWARF section data
objtool: Free insns when done
objtool: Get rid of reloc->rel[a]
objtool: Shrink elf hash nodes
objtool: Shrink reloc->sym_reloc_entry
objtool: Get rid of reloc->jump_table_start
objtool: Get rid of reloc->addend
objtool: Get rid of reloc->type
objtool: Get rid of reloc->offset
objtool: Get rid of reloc->idx
objtool: Get rid of reloc->list
objtool: Allocate relocs in advance for new rela sections
objtool: Add for_each_reloc()
objtool: Don't free memory in elf_close()
objtool: Keep GElf_Rel[a] structs synced
objtool: Add elf_create_section_pair()
objtool: Add mark_sec_changed()
objtool: Fix reloc_hash size
objtool: Consolidate rel/rela handling
...
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.