Files
hakmem/core/box/front_gate_classifier.d
Moe Charm (CI) 72b38bc994 Phase E3-FINAL: Fix Box API offset bugs - ALL classes now use correct offsets
## 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>
2025-11-13 06:50:20 +09:00

54 lines
2.2 KiB
Makefile

core/box/front_gate_classifier.o: core/box/front_gate_classifier.c \
core/box/front_gate_classifier.h core/box/../tiny_region_id.h \
core/box/../hakmem_build_flags.h core/box/../tiny_box_geometry.h \
core/box/../hakmem_tiny_superslab_constants.h \
core/box/../hakmem_tiny_config.h core/box/../ptr_track.h \
core/box/../hakmem_tiny_superslab.h \
core/box/../superslab/superslab_types.h \
core/hakmem_tiny_superslab_constants.h \
core/box/../superslab/superslab_inline.h \
core/box/../superslab/superslab_types.h core/tiny_debug_ring.h \
core/hakmem_build_flags.h core/tiny_remote.h \
core/box/../superslab/../tiny_box_geometry.h \
core/box/../superslab/../box/tiny_next_ptr_box.h \
core/hakmem_tiny_config.h core/tiny_nextptr.h \
core/box/../tiny_debug_ring.h core/box/../tiny_remote.h \
core/box/../superslab/superslab_inline.h \
core/box/../hakmem_build_flags.h core/box/../hakmem_internal.h \
core/box/../hakmem.h core/box/../hakmem_config.h \
core/box/../hakmem_features.h core/box/../hakmem_sys.h \
core/box/../hakmem_whale.h core/box/../hakmem_tiny_config.h \
core/box/../hakmem_super_registry.h core/box/../hakmem_tiny_superslab.h
core/box/front_gate_classifier.h:
core/box/../tiny_region_id.h:
core/box/../hakmem_build_flags.h:
core/box/../tiny_box_geometry.h:
core/box/../hakmem_tiny_superslab_constants.h:
core/box/../hakmem_tiny_config.h:
core/box/../ptr_track.h:
core/box/../hakmem_tiny_superslab.h:
core/box/../superslab/superslab_types.h:
core/hakmem_tiny_superslab_constants.h:
core/box/../superslab/superslab_inline.h:
core/box/../superslab/superslab_types.h:
core/tiny_debug_ring.h:
core/hakmem_build_flags.h:
core/tiny_remote.h:
core/box/../superslab/../tiny_box_geometry.h:
core/box/../superslab/../box/tiny_next_ptr_box.h:
core/hakmem_tiny_config.h:
core/tiny_nextptr.h:
core/box/../tiny_debug_ring.h:
core/box/../tiny_remote.h:
core/box/../superslab/superslab_inline.h:
core/box/../hakmem_build_flags.h:
core/box/../hakmem_internal.h:
core/box/../hakmem.h:
core/box/../hakmem_config.h:
core/box/../hakmem_features.h:
core/box/../hakmem_sys.h:
core/box/../hakmem_whale.h:
core/box/../hakmem_tiny_config.h:
core/box/../hakmem_super_registry.h:
core/box/../hakmem_tiny_superslab.h: