Files
hakmem/core/hakmem_tiny_phase6_wrappers_box.inc
Moe Charm (CI) 0546454168 WIP: Add TLS SLL validation and SuperSlab registry fallback
ChatGPT's diagnostic changes to address TLS_SLL_HDR_RESET issue.
Current status: Partial mitigation, but root cause remains.

Changes Applied:
1. SuperSlab Registry Fallback (hakmem_super_registry.h)
   - Added legacy table probe when hash map lookup misses
   - Prevents NULL returns for valid SuperSlabs during initialization
   - Status:  Works but may hide underlying registration issues

2. TLS SLL Push Validation (tls_sll_box.h)
   - Reject push if SuperSlab lookup returns NULL
   - Reject push if class_idx mismatch detected
   - Added [TLS_SLL_PUSH_NO_SS] diagnostic message
   - Status:  Prevents list corruption (defensive)

3. SuperSlab Allocation Class Fix (superslab_allocate.c)
   - Pass actual class_idx to sp_internal_allocate_superslab
   - Prevents dummy class=8 causing OOB access
   - Status:  Root cause fix for allocation path

4. Debug Output Additions
   - First 256 push/pop operations traced
   - First 4 mismatches logged with details
   - SuperSlab registration state logged
   - Status:  Diagnostic tool (not a fix)

5. TLS Hint Box Removed
   - Deleted ss_tls_hint_box.{c,h} (Phase 1 optimization)
   - Simplified to focus on stability first
   - Status:  Can be re-added after root cause fixed

Current Problem (REMAINS UNSOLVED):
- [TLS_SLL_HDR_RESET] still occurs after ~60 seconds of sh8bench
- Pointer is 16 bytes offset from expected (class 1 → class 2 boundary)
- hak_super_lookup returns NULL for that pointer
- Suggests: Use-After-Free, Double-Free, or pointer arithmetic error

Root Cause Analysis:
- Pattern: Pointer offset by +16 (one class 1 stride)
- Timing: Cumulative problem (appears after 60s, not immediately)
- Location: Header corruption detected during TLS SLL pop

Remaining Issues:
⚠️ Registry fallback is defensive (may hide registration bugs)
⚠️ Push validation prevents symptoms but not root cause
⚠️ 16-byte pointer offset source unidentified

Next Steps for Investigation:
1. Full pointer arithmetic audit (Magazine ⇔ TLS SLL paths)
2. Enhanced logging at HDR_RESET point:
   - Expected vs actual pointer value
   - Pointer provenance (where it came from)
   - Allocation trace for that block
3. Verify Headerless flag is OFF throughout build
4. Check for double-offset application in conversions

Technical Assessment:
- 60% root cause fixes (allocation class, validation)
- 40% defensive mitigation (registry fallback, push rejection)

Performance Impact:
- Registry fallback: +10-30 cycles on cold path (negligible)
- Push validation: +5-10 cycles per push (acceptable)
- Overall: < 2% performance impact estimated

Related Issues:
- Phase 1 TLS Hint Box removed temporarily
- Phase 2 Headerless blocked until stability achieved

🤖 Generated with Claude Code (https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>
2025-12-03 20:42:28 +09:00

109 lines
4.4 KiB
C++

// Phase 6-1.7: Box Theory Refactoring - Mutual exclusion check
#if HAKMEM_TINY_PHASE6_BOX_REFACTOR
#if defined(HAKMEM_TINY_PHASE6_METADATA) || defined(HAKMEM_TINY_PHASE6_ULTRA_SIMPLE)
#error "Cannot enable PHASE6_BOX_REFACTOR with other Phase 6 options"
#endif
// Box 1: Atomic Operations (Layer 0 - Foundation)
#include "tiny_atomic.h"
// Box 5: Allocation Fast Path (Layer 1 - 3-4 instructions)
#include "tiny_alloc_fast.inc.h"
// Box 6: Free Fast Path (Layer 2 - 2-3 instructions)
#include "tiny_free_fast.inc.h"
// ---------------- Refill count (Front) global config ----------------
// Parsed once at init; hot path reads plain ints (no getenv).
int g_refill_count_global = 0; // HAKMEM_TINY_REFILL_COUNT
int g_refill_count_hot = 0; // HAKMEM_TINY_REFILL_COUNT_HOT
int g_refill_count_mid = 0; // HAKMEM_TINY_REFILL_COUNT_MID
int g_refill_count_class[TINY_NUM_CLASSES] = {0}; // HAKMEM_TINY_REFILL_COUNT_C{0..7}
// Export wrapper functions for hakmem.c to call
// Phase 6-1.7 Optimization: Remove diagnostic overhead, rely on LTO for inlining
void* hak_tiny_alloc_fast_wrapper(size_t size) {
static _Atomic int g_alloc_fast_trace = 0;
if (atomic_fetch_add_explicit(&g_alloc_fast_trace, 1, memory_order_relaxed) < 128) {
HAK_TRACE("[tiny_alloc_fast_wrapper_enter]\n");
}
// Phase E5: Ultra fast path (8-instruction alloc, bypasses all layers)
// Enable with: HAKMEM_ULTRA_FAST_PATH=1 (compile-time)
#if HAKMEM_ULTRA_FAST_PATH
void* ret = tiny_alloc_fast_ultra(size);
if (ret) return ret;
// Miss → fallback to full fast path
#endif
// Bench-only ultra-short path: bypass diagnostics and pointer tracking
// Enable with: HAKMEM_BENCH_FAST_FRONT=1
static int g_bench_fast_front = -1;
if (__builtin_expect(g_bench_fast_front == -1, 0)) {
const char* e = getenv("HAKMEM_BENCH_FAST_FRONT");
g_bench_fast_front = (e && *e && *e != '0') ? 1 : 0;
}
if (__builtin_expect(g_bench_fast_front, 0)) {
return tiny_alloc_fast(size);
}
static _Atomic uint64_t wrapper_call_count = 0;
uint64_t call_num = atomic_fetch_add(&wrapper_call_count, 1);
// Pointer tracking init (first call only)
PTR_TRACK_INIT();
// PRIORITY 3: Periodic canary validation (every 1000 ops)
periodic_canary_check(call_num, "hak_tiny_alloc_fast_wrapper");
// Box I: Periodic full integrity check (every 5000 ops)
#if HAKMEM_INTEGRITY_LEVEL >= 3
if ((call_num % 5000) == 0) {
extern void integrity_periodic_full_check(const char*);
integrity_periodic_full_check("periodic check in alloc wrapper");
}
#endif
#if !HAKMEM_BUILD_RELEASE
if (call_num > 14250 && call_num < 14280 && size <= 1024) {
fprintf(stderr, "[HAK_TINY_ALLOC_FAST_WRAPPER] call=%lu size=%zu\n", call_num, size);
fflush(stderr);
}
#endif
void* result = tiny_alloc_fast(size);
#if !HAKMEM_BUILD_RELEASE
if (call_num > 14250 && call_num < 14280 && size <= 1024) {
fprintf(stderr, "[HAK_TINY_ALLOC_FAST_WRAPPER] call=%lu returned %p\n", call_num, result);
fflush(stderr);
}
#endif
return result;
}
void hak_tiny_free_fast_wrapper(void* ptr) {
// Phase E5: Ultra fast path (6-8 instruction free)
#if HAKMEM_ULTRA_FAST_PATH
tiny_free_fast_ultra(ptr);
return;
#endif
static _Atomic uint64_t free_call_count = 0;
uint64_t call_num = atomic_fetch_add(&free_call_count, 1);
if (call_num > 14135 && call_num < 14145) {
fprintf(stderr, "[HAK_TINY_FREE_FAST_WRAPPER] call=%lu ptr=%p\n", call_num, ptr);
fflush(stderr);
}
tiny_free_fast(ptr);
if (call_num > 14135 && call_num < 14145) {
fprintf(stderr, "[HAK_TINY_FREE_FAST_WRAPPER] call=%lu completed\n", call_num);
fflush(stderr);
}
}
// HAKMEM_TINY_PHASE6_ULTRA_SIMPLE - REMOVED (dead code cleanup 2025-11-27)
#elif defined(HAKMEM_TINY_PHASE6_METADATA)
// Phase 6-1.6: Metadata header (recommended)
#include "hakmem_tiny_metadata.inc"
#endif