72b38bc994
## Root Cause Analysis (GPT5) **Physical Layout Constraints**: - Class 0: 8B = [1B header][7B payload] → offset 1 = 9B needed = ❌ IMPOSSIBLE - Class 1-6: >=16B = [1B header][15B+ payload] → offset 1 = ✅ POSSIBLE - Class 7: 1KB → offset 0 (compatibility) **Correct Specification**: - HAKMEM_TINY_HEADER_CLASSIDX != 0: - Class 0, 7: next at offset 0 (overwrites header when on freelist) - Class 1-6: next at offset 1 (after header) - HAKMEM_TINY_HEADER_CLASSIDX == 0: - All classes: next at offset 0 **Previous Bug**: - Attempted "ALL classes offset 1" unification - Class 0 with offset 1 caused immediate SEGV (9B > 8B block size) - Mixed 2-arg/3-arg API caused confusion ## Fixes Applied ### 1. Restored 3-Argument Box API (core/box/tiny_next_ptr_box.h) ```c // Correct signatures void tiny_next_write(int class_idx, void* base, void* next_value) void* tiny_next_read(int class_idx, const void* base) // Correct offset calculation size_t offset = (class_idx == 0 || class_idx == 7) ? 0 : 1; ``` ### 2. Updated 123+ Call Sites Across 34 Files - hakmem_tiny_hot_pop_v4.inc.h (4 locations) - hakmem_tiny_fastcache.inc.h (3 locations) - hakmem_tiny_tls_list.h (12 locations) - superslab_inline.h (5 locations) - tiny_fastcache.h (3 locations) - ptr_trace.h (macro definitions) - tls_sll_box.h (2 locations) - + 27 additional files Pattern: `tiny_next_read(base)` → `tiny_next_read(class_idx, base)` Pattern: `tiny_next_write(base, next)` → `tiny_next_write(class_idx, base, next)` ### 3. Added Sentinel Detection Guards - tiny_fast_push(): Block nodes with sentinel in ptr or ptr->next - tls_list_push(): Block nodes with sentinel in ptr or ptr->next - Defense-in-depth against remote free sentinel leakage ## Verification (GPT5 Report) **Test Command**: `./out/release/bench_random_mixed_hakmem --iterations=70000` **Results**: - ✅ Main loop completed successfully - ✅ Drain phase completed successfully - ✅ NO SEGV (previous crash at iteration 66151 is FIXED) - ℹ️ Final log: "tiny_alloc(1024) failed" is normal fallback to Mid/ACE layers **Analysis**: - Class 0 immediate SEGV: ✅ RESOLVED (correct offset 0 now used) - 66K iteration crash: ✅ RESOLVED (offset consistency fixed) - Box API conflicts: ✅ RESOLVED (unified 3-arg API) ## Technical Details ### Offset Logic Justification ``` Class 0: 8B block → next pointer (8B) fits ONLY at offset 0 Class 1: 16B block → next pointer (8B) fits at offset 1 (after 1B header) Class 2: 32B block → next pointer (8B) fits at offset 1 ... Class 6: 512B block → next pointer (8B) fits at offset 1 Class 7: 1024B block → offset 0 for legacy compatibility ``` ### Files Modified (Summary) - Core API: `box/tiny_next_ptr_box.h` - Hot paths: `hakmem_tiny_hot_pop*.inc.h`, `tiny_fastcache.h` - TLS layers: `hakmem_tiny_tls_list.h`, `hakmem_tiny_tls_ops.h` - SuperSlab: `superslab_inline.h`, `tiny_superslab_*.inc.h` - Refill: `hakmem_tiny_refill.inc.h`, `tiny_refill_opt.h` - Free paths: `tiny_free_magazine.inc.h`, `tiny_superslab_free.inc.h` - Documentation: Multiple Phase E3 reports ## Remaining Work None for Box API offset bugs - all structural issues resolved. Future enhancements (non-critical): - Periodic `grep -R '*(void**)' core/` to detect direct pointer access violations - Enforce Box API usage via static analysis - Document offset rationale in architecture docs 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
60 lines
1.7 KiB
C
60 lines
1.7 KiB
C
#pragma once
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/*
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* box/tiny_next_ptr_box.h
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*
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* Tiny next-pointer Box API (thin wrapper over tiny_nextptr.h)
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*
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* このヘッダは Phase E1-CORRECT で確定した next オフセット仕様に従い、
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* すべての tiny freelist / TLS / fast-cache / refill / SLL が経由すべき
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* 「唯一の Box API」を提供する。
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*
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* 仕様は tiny_nextptr.h と完全一致:
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*
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* HAKMEM_TINY_HEADER_CLASSIDX != 0:
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* - Class 0: next_off = 0 (free中は header を潰す)
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* - Class 1-6: next_off = 1
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* - Class 7: next_off = 0
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*
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* HAKMEM_TINY_HEADER_CLASSIDX == 0:
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* - 全クラス: next_off = 0
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*
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* 呼び出し規約:
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* - base: 「内部 box 基底 (header位置または従来base)」
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* - class_idx: size class index (0-7)
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*
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* 禁止事項:
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* - ここを通さずに next オフセットを手計算すること
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* - 直接 *(void**) で next を読む/書くこと
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*/
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#include <stdint.h>
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#include "hakmem_tiny_config.h"
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#include "tiny_nextptr.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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// Box API: write next pointer
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static inline void tiny_next_write(int class_idx, void *base, void *next_value) {
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tiny_next_store(base, class_idx, next_value);
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}
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// Box API: read next pointer
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static inline void *tiny_next_read(int class_idx, const void *base) {
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return tiny_next_load(base, class_idx);
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}
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/*
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* Greppable macros:
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* - 既存コードは TINY_NEXT_READ/WRITE か tiny_next_read/write を使う。
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* - これらから tiny_nextptr.h 実装へ一元的に到達する。
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*/
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#define TINY_NEXT_WRITE(cls_, base_, next_) tiny_next_write((cls_), (base_), (next_))
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#define TINY_NEXT_READ(cls_, base_) tiny_next_read((cls_), (base_))
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#ifdef __cplusplus
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}
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#endif
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