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Message-ID: <20250411054105.2341982-1-mingo@kernel.org>
Date: Fri, 11 Apr 2025 07:40:12 +0200
From: Ingo Molnar <mingo@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: Juergen Gross <jgross@...e.com>,
"H . Peter Anvin" <hpa@...or.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Peter Zijlstra <peterz@...radead.org>,
Borislav Petkov <bp@...en8.de>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...nel.org>
Subject: [PATCH -v3 00/53] Simplify, reorganize and clean up the x86 text-patching code (alternative.c)
This series has 3 major parts after pending x86.alternatives commits such as the
scalability improvement by Eric Dumazet:
(1)
The first major part of this series performs a thorough text-patching API namespace
cleanup discussed with Linus for the -v1 series:
# boot/UP APIs & single-thread helpers:
text_poke()
text_poke_kgdb()
[ unchanged APIs: ] text_poke_copy()
text_poke_copy_locked()
text_poke_set()
text_poke_addr()
# SMP API & helpers namespace:
text_poke_bp() => smp_text_poke_single()
text_poke_loc_init() => __smp_text_poke_batch_add()
text_poke_queue() => smp_text_poke_batch_add()
text_poke_finish() => smp_text_poke_batch_finish()
text_poke_flush() => [removed]
text_poke_bp_batch() => smp_text_poke_batch_process()
poke_int3_handler() => smp_text_poke_int3_handler()
text_poke_sync() => smp_text_poke_sync_each_cpu()
(2)
The second part of the series simplifies and standardizes the SMP batch-patching
data & types & accessors namespace, around the new text_poke_array* namespace:
int3_patching_desc = [removed]
temp_mm_state_t => [removed]
try_get_desc() => try_get_text_poke_array()
put_desc() => put_text_poke_array()
tp_vec,tp_vec_nr => text_poke_array
int3_refs => text_poke_array_refs
- All constants got moved into the TEXT_POKE_* namespace
- All local variables and function parameters got standardized around
the 'tpl' naming scheme. No more toilet paper references. ;-)
(3)
The third part of the series contains additional patches, that
together with the data-namespace simplification changes remove
about 3 layers of unnecessary indirections and simplify/streamline
various aspects of the code:
x86/alternatives: Remove duplicate 'text_poke_early()' prototype
x86/alternatives: Update comments in int3_emulate_push()
x86/alternatives: Remove the confusing, inaccurate & unnecessary 'temp_mm_state_t' abstraction
x86/alternatives: Add text_mutex) assert to smp_text_poke_batch_flush()
x86/alternatives: Use non-inverted logic instead of 'tp_order_fail()'
x86/alternatives: Remove the 'addr == NULL means forced-flush' hack from smp_text_poke_batch_finish()/smp_text_poke_batch_flush()/text_poke_addr_ordered()
x86/alternatives: Simplify smp_text_poke_single() by using tp_vec and existing APIs
x86/alternatives: Introduce 'struct smp_text_poke_array' and move tp_vec and tp_vec_nr to it
x86/alternatives: Remove the tp_vec indirection
x86/alternatives: Simplify try_get_text_poke_array()
x86/alternatives: Simplify smp_text_poke_int3_trap_handler()
x86/alternatives: Simplify smp_text_poke_batch_process()
x86/alternatives: Move the text_poke_array manipulation into text_poke_int3_loc_init() and rename it to __smp_text_poke_batch_add()
x86/alternatives: Remove the mixed-patching restriction on smp_text_poke_single()
x86/alternatives: Document 'smp_text_poke_single()'
x86/alternatives: Add documentation for smp_text_poke_batch_add()
x86/alternatives: Move text_poke_array completion from smp_text_poke_batch_finish() and smp_text_poke_batch_flush() to smp_text_poke_batch_process()
x86/alternatives: Simplify text_poke_addr_ordered()
x86/alternatives: Constify text_poke_addr()
x86/alternatives: Simplify and clean up patch_cmp()
x86/alternatives: Standardize on 'tpl' local variable names for 'struct smp_text_poke_loc *'
x86/alternatives: Simplify the #include section
x86/alternatives: Move declarations of vmlinux.lds.S defined section symbols to <asm/alternative.h>
x86/alternatives: Remove 'smp_text_poke_batch_flush()'
x86/alternatives: Update the comments in smp_text_poke_batch_process()
x86/alternatives: Rename 'apply_relocation()' to 'text_poke_apply_relocation()'
x86/alternatives: Add comment about noinstr expectations
x86/alternatives: Make smp_text_poke_batch_process() subsume smp_text_poke_batch_finish()
Various APIs also had their names clarified, as part of the renames.
I also added comments where justified.
There's almost no functional changes in the end, other than
mixed smp_text_poke_single() & smp_text_poke_batch_add() calls
are now probably working better than before - although I'm not
aware of such in-tree usage at the moment.
After these changes there's a reduction of about ~20 lines of
code if we exclude comments, and some reduction in text size:
text data bss dec hex filename
13637 1009 4112 18758 4946 arch/x86/kernel/alternative.o.before
13549 1009 4156 18714 491a arch/x86/kernel/alternative.o.after
But the main goal was to perform a thorough round of source code TLC,
to make the code easier to read & maintain, and to remove a chunk
of technical debt accumulated incrementally over 20 years, which
improvements are only partly reflected in line count and code size decreases.
This tree can be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip WIP.x86/alternatives
Thanks,
Ingo
================>
Eric Dumazet (1):
x86/alternatives: Improve code-patching scalability by removing false sharing in poke_int3_handler()
Ingo Molnar (50):
x86/alternatives: Rename 'struct bp_patching_desc' to 'struct int3_patching_desc'
x86/alternatives: Rename 'bp_refs' to 'int3_refs'
x86/alternatives: Rename 'text_poke_bp_batch()' to 'smp_text_poke_batch_process()'
x86/alternatives: Rename 'text_poke_bp()' to 'smp_text_poke_single()'
x86/alternatives: Rename 'poke_int3_handler()' to 'smp_text_poke_int3_handler()'
x86/alternatives: Rename 'poking_mm' to 'text_poke_mm'
x86/alternatives: Rename 'poking_addr' to 'text_poke_mm_addr'
x86/alternatives: Rename 'bp_desc' to 'int3_desc'
x86/alternatives: Remove duplicate 'text_poke_early()' prototype
x86/alternatives: Update comments in int3_emulate_push()
x86/alternatives: Remove the confusing, inaccurate & unnecessary 'temp_mm_state_t' abstraction
x86/alternatives: Rename 'text_poke_flush()' to 'smp_text_poke_batch_flush()'
x86/alternatives: Rename 'text_poke_finish()' to 'smp_text_poke_batch_finish()'
x86/alternatives: Rename 'text_poke_queue()' to 'smp_text_poke_batch_add()'
x86/alternatives: Rename 'text_poke_loc_init()' to 'text_poke_int3_loc_init()'
x86/alternatives: Rename 'struct text_poke_loc' to 'struct smp_text_poke_loc'
x86/alternatives: Rename 'struct int3_patching_desc' to 'struct text_poke_int3_vec'
x86/alternatives: Rename 'int3_desc' to 'int3_vec'
x86/alternatives: Add text_mutex) assert to smp_text_poke_batch_flush()
x86/alternatives: Use non-inverted logic instead of 'tp_order_fail()'
x86/alternatives: Remove the 'addr == NULL means forced-flush' hack from smp_text_poke_batch_finish()/smp_text_poke_batch_flush()/text_poke_addr_ordered()
x86/alternatives: Simplify smp_text_poke_single() by using tp_vec and existing APIs
x86/alternatives: Assert that smp_text_poke_int3_handler() can only ever handle 'tp_vec[]' based requests
x86/alternatives: Assert input parameters in smp_text_poke_batch_process()
x86/alternatives: Introduce 'struct smp_text_poke_array' and move tp_vec and tp_vec_nr to it
x86/alternatives: Remove the tp_vec indirection
x86/alternatives: Rename 'try_get_desc()' to 'try_get_text_poke_array()'
x86/alternatives: Rename 'put_desc()' to 'put_text_poke_array()'
x86/alternatives: Simplify try_get_text_poke_array()
x86/alternatives: Simplify smp_text_poke_int3_handler()
x86/alternatives: Simplify smp_text_poke_batch_process()
x86/alternatives: Rename 'int3_refs' to 'text_poke_array_refs'
x86/alternatives: Move the text_poke_array manipulation into text_poke_int3_loc_init() and rename it to __smp_text_poke_batch_add()
x86/alternatives: Remove the mixed-patching restriction on smp_text_poke_single()
x86/alternatives: Document 'smp_text_poke_single()'
x86/alternatives: Add documentation for smp_text_poke_batch_add()
x86/alternatives: Move text_poke_array completion from smp_text_poke_batch_finish() and smp_text_poke_batch_flush() to smp_text_poke_batch_process()
x86/alternatives: Rename 'text_poke_sync()' to 'smp_text_poke_sync_each_cpu()'
x86/alternatives: Simplify text_poke_addr_ordered()
x86/alternatives: Constify text_poke_addr()
x86/alternatives: Simplify and clean up patch_cmp()
x86/alternatives: Standardize on 'tpl' local variable names for 'struct smp_text_poke_loc *'
x86/alternatives: Rename 'TP_ARRAY_NR_ENTRIES_MAX' to 'TEXT_POKE_ARRAY_MAX'
x86/alternatives: Rename 'POKE_MAX_OPCODE_SIZE' to 'TEXT_POKE_MAX_OPCODE_SIZE'
x86/alternatives: Simplify the #include section
x86/alternatives: Move declarations of vmlinux.lds.S defined section symbols to <asm/alternative.h>
x86/alternatives: Remove 'smp_text_poke_batch_flush()'
x86/alternatives: Update the comments in smp_text_poke_batch_process()
x86/alternatives: Rename 'apply_relocation()' to 'text_poke_apply_relocation()'
x86/alternatives: Add comment about noinstr expectations
Nikolay Borisov (1):
x86/alternatives: Make smp_text_poke_batch_process() subsume smp_text_poke_batch_finish()
Peter Zijlstra (1):
x86/alternatives: Document the text_poke_bp_batch() synchronization rules a bit more
arch/x86/include/asm/alternative.h | 6 +
arch/x86/include/asm/text-patching.h | 29 +--
arch/x86/kernel/alternative.c | 391 +++++++++++++++++------------------
arch/x86/kernel/callthunks.c | 6 +-
arch/x86/kernel/ftrace.c | 18 +-
arch/x86/kernel/jump_label.c | 6 +-
arch/x86/kernel/kprobes/core.c | 4 +-
arch/x86/kernel/kprobes/opt.c | 6 +-
arch/x86/kernel/module.c | 2 +-
arch/x86/kernel/static_call.c | 2 +-
arch/x86/kernel/traps.c | 6 +-
arch/x86/mm/init.c | 16 +-
arch/x86/net/bpf_jit_comp.c | 2 +-
13 files changed, 241 insertions(+), 253 deletions(-)
--
2.45.2
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