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TSRM: make CG, EG, SCNG and AG compile-time offsets #22287

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39 changes: 39 additions & 0 deletions TSRM/TSRM.c
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,15 @@ struct _tsrm_tls_entry {
tsrm_tls_entry *next;
};

#if defined(__cplusplus) || defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 202311L)
# define TSRM_STATIC_ASSERT(c, m) static_assert((c), m)
#elif defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 201112L) /* C11 */
# define TSRM_STATIC_ASSERT(c, m) _Static_assert((c), m)
#else
# define TSRM_STATIC_ASSERT(c, m)
#endif
TSRM_STATIC_ASSERT(TSRM_ALIGNED_SIZE(sizeof(tsrm_tls_entry)) == TSRM_FAST_RESERVED_BASE,
"TSRM_FAST_RESERVED_BASE must equal the tsrm_tls_entry header size");
Comment on lines +39 to +47

@henderkes henderkes Jun 12, 2026

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so this is a two-fold problem:

  • duplicated ZEND_STATIC_ASSERT copy - tsrm can't use zend_portability, because zend_portability depends on tsrm.h
  • tsrm_ls_entry size is only known in this file, not in tsrm.h consumers.
  • AG size can be consumed at runtime, so it gets the last slot, but it's structurally the same problem

In C++ this would be a simple consteval function in the header, but I have no idea how to make it work in C. So I kept the definition private, but force it to the specific size it has.


typedef struct {
size_t size;
Expand Down Expand Up @@ -319,6 +328,14 @@ TSRM_API void tsrm_reserve(size_t size)
}/*}}}*/


/* Reserve the front of the fast space for fixed-offset fast resources, so the
* bump-allocated ones (ts_allocate_fast_id) are placed after it. */
TSRM_API void tsrm_reserve_fast_front(size_t size)
{/*{{{*/
tsrm_reserved_pos = TSRM_ALIGNED_SIZE(size);
}/*}}}*/


/* allocates a new fast thread-safe-resource id */
TSRM_API ts_rsrc_id ts_allocate_fast_id(ts_rsrc_id *rsrc_id, size_t *offset, size_t size, ts_allocate_ctor ctor, ts_allocate_dtor dtor)
{/*{{{*/
Expand Down Expand Up @@ -368,6 +385,28 @@ TSRM_API ts_rsrc_id ts_allocate_fast_id(ts_rsrc_id *rsrc_id, size_t *offset, siz
return *rsrc_id;
}/*}}}*/


/* Allocate a fast resource id at a fixed, compile-time-constant offset.
* Like tsrm_reserve(), assumes single-threaded startup. */
TSRM_API ts_rsrc_id ts_allocate_fast_id_at(ts_rsrc_id *rsrc_id, size_t *offset, size_t fixed_offset, size_t size, ts_allocate_ctor ctor, ts_allocate_dtor dtor)
{/*{{{*/
size_t saved_pos = tsrm_reserved_pos;

if (fixed_offset - TSRM_FAST_RESERVED_BASE > tsrm_reserved_size) {
TSRM_ERROR((TSRM_ERROR_LEVEL_ERROR, "Unable to allocate space for fixed fast resource"));
*rsrc_id = 0;
*offset = 0;
return 0;
}
tsrm_reserved_pos = fixed_offset - TSRM_FAST_RESERVED_BASE;
ts_allocate_fast_id(rsrc_id, offset, size, ctor, dtor);
/* keep ordinary (bump-allocated) fast resources past the high-water mark */
if (tsrm_reserved_pos < saved_pos) {
tsrm_reserved_pos = saved_pos;
}
return *rsrc_id;
}/*}}}*/

static void set_thread_local_storage_resource_to(tsrm_tls_entry *thread_resource)
{
tsrm_tls_set(thread_resource);
Expand Down
7 changes: 7 additions & 0 deletions TSRM/TSRM.h
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Expand Up @@ -75,6 +75,8 @@ typedef void (*ts_allocate_dtor)(void *);

#define THREAD_HASH_OF(thr,ts) (unsigned long)thr%(unsigned long)ts

#define TSRM_FAST_RESERVED_BASE TSRM_ALIGNED_SIZE(4 * sizeof(void *))

#ifdef __cplusplus
extern "C" {
#endif
Expand All @@ -94,6 +96,11 @@ TSRM_API ts_rsrc_id ts_allocate_id(ts_rsrc_id *rsrc_id, size_t size, ts_allocate
TSRM_API void tsrm_reserve(size_t size);
TSRM_API ts_rsrc_id ts_allocate_fast_id(ts_rsrc_id *rsrc_id, size_t *offset, size_t size, ts_allocate_ctor ctor, ts_allocate_dtor dtor);

/* Fast resources at caller-chosen, compile-time-constant offsets. The fixed
* prefix must be reserved after tsrm_reserve() and before any fast id. */
TSRM_API void tsrm_reserve_fast_front(size_t size);
TSRM_API ts_rsrc_id ts_allocate_fast_id_at(ts_rsrc_id *rsrc_id, size_t *offset, size_t fixed_offset, size_t size, ts_allocate_ctor ctor, ts_allocate_dtor dtor);

/* fetches the requested resource for the current thread */
TSRM_API void *ts_resource_ex(ts_rsrc_id id, THREAD_T *th_id);
#define ts_resource(id) ts_resource_ex(id, NULL)
Expand Down
9 changes: 6 additions & 3 deletions Zend/zend.c
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Expand Up @@ -1019,9 +1019,12 @@ void zend_startup(zend_utility_functions *utility_functions) /* {{{ */
zend_init_rsrc_list_dtors();

#ifdef ZTS
ts_allocate_fast_id(&compiler_globals_id, &compiler_globals_offset, sizeof(zend_compiler_globals), (ts_allocate_ctor) compiler_globals_ctor, (ts_allocate_dtor) compiler_globals_dtor);
ts_allocate_fast_id(&executor_globals_id, &executor_globals_offset, sizeof(zend_executor_globals), (ts_allocate_ctor) executor_globals_ctor, (ts_allocate_dtor) executor_globals_dtor);
ts_allocate_fast_id(&language_scanner_globals_id, &language_scanner_globals_offset, sizeof(zend_php_scanner_globals), (ts_allocate_ctor) php_scanner_globals_ctor, NULL);
ts_allocate_fast_id_at(&compiler_globals_id, &compiler_globals_offset, ZEND_CG_OFFSET, sizeof(zend_compiler_globals), (ts_allocate_ctor) compiler_globals_ctor, (ts_allocate_dtor) compiler_globals_dtor);
ts_allocate_fast_id_at(&executor_globals_id, &executor_globals_offset, ZEND_EG_OFFSET, sizeof(zend_executor_globals), (ts_allocate_ctor) executor_globals_ctor, (ts_allocate_dtor) executor_globals_dtor);
ts_allocate_fast_id_at(&language_scanner_globals_id, &language_scanner_globals_offset, ZEND_SCNG_OFFSET, sizeof(zend_php_scanner_globals), (ts_allocate_ctor) php_scanner_globals_ctor, NULL);
ZEND_ASSERT(compiler_globals_offset == ZEND_CG_OFFSET);
ZEND_ASSERT(executor_globals_offset == ZEND_EG_OFFSET);
ZEND_ASSERT(language_scanner_globals_offset == ZEND_SCNG_OFFSET);
ts_allocate_fast_id(&ini_scanner_globals_id, &ini_scanner_globals_offset, sizeof(zend_ini_scanner_globals), (ts_allocate_ctor) ini_scanner_globals_ctor, NULL);
compiler_globals = ts_resource(compiler_globals_id);
executor_globals = ts_resource(executor_globals_id);
Expand Down
5 changes: 3 additions & 2 deletions Zend/zend_alloc.c
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Expand Up @@ -2614,7 +2614,7 @@ typedef struct _zend_alloc_globals {
#ifdef ZTS
static int alloc_globals_id;
static size_t alloc_globals_offset;
# define AG(v) ZEND_TSRMG_FAST(alloc_globals_offset, zend_alloc_globals *, v)
# define AG(v) ZEND_TSRMG_FAST(ZEND_AG_OFFSET, zend_alloc_globals *, v)
#else
# define AG(v) (alloc_globals.v)
static zend_alloc_globals alloc_globals;
Expand Down Expand Up @@ -3335,7 +3335,8 @@ ZEND_API void start_memory_manager(void)
# endif
#endif
#ifdef ZTS
ts_allocate_fast_id(&alloc_globals_id, &alloc_globals_offset, sizeof(zend_alloc_globals), (ts_allocate_ctor) alloc_globals_ctor, (ts_allocate_dtor) alloc_globals_dtor);
ts_allocate_fast_id_at(&alloc_globals_id, &alloc_globals_offset, ZEND_AG_OFFSET, sizeof(zend_alloc_globals), (ts_allocate_ctor) alloc_globals_ctor, (ts_allocate_dtor) alloc_globals_dtor);
ZEND_ASSERT(alloc_globals_offset == ZEND_AG_OFFSET);
#else
alloc_globals_ctor(&alloc_globals);
#endif
Expand Down
9 changes: 9 additions & 0 deletions Zend/zend_globals.h
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Expand Up @@ -329,6 +329,15 @@ struct _zend_executor_globals {
void *reserved[ZEND_MAX_RESERVED_RESOURCES];
};

#ifdef ZTS
/* Fixed compile-time offsets of the hot globals in the TSRM fast space.
* AG is last, sizeof(zend_alloc_globals) isn't header-visible. */
# define ZEND_CG_OFFSET (TSRM_FAST_RESERVED_BASE)
# define ZEND_EG_OFFSET (ZEND_CG_OFFSET + TSRM_ALIGNED_SIZE(sizeof(zend_compiler_globals)))
# define ZEND_SCNG_OFFSET (ZEND_EG_OFFSET + TSRM_ALIGNED_SIZE(sizeof(zend_executor_globals)))
# define ZEND_AG_OFFSET (ZEND_SCNG_OFFSET + TSRM_ALIGNED_SIZE(sizeof(zend_php_scanner_globals)))
#endif

#define EG_FLAGS_INITIAL (0)
#define EG_FLAGS_IN_SHUTDOWN (1<<0)
#define EG_FLAGS_OBJECT_STORE_NO_REUSE (1<<1)
Expand Down
6 changes: 3 additions & 3 deletions Zend/zend_globals_macros.h
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Expand Up @@ -30,7 +30,7 @@ BEGIN_EXTERN_C()

/* Compiler */
#ifdef ZTS
# define CG(v) ZEND_TSRMG_FAST(compiler_globals_offset, zend_compiler_globals *, v)
# define CG(v) ZEND_TSRMG_FAST(ZEND_CG_OFFSET, zend_compiler_globals *, v)
#else
# define CG(v) (compiler_globals.v)
extern ZEND_API struct _zend_compiler_globals compiler_globals;
Expand All @@ -40,15 +40,15 @@ ZEND_API int zendparse(void);

/* Executor */
#ifdef ZTS
# define EG(v) ZEND_TSRMG_FAST(executor_globals_offset, zend_executor_globals *, v)
# define EG(v) ZEND_TSRMG_FAST(ZEND_EG_OFFSET, zend_executor_globals *, v)
#else
# define EG(v) (executor_globals.v)
extern ZEND_API zend_executor_globals executor_globals;
#endif

/* Language Scanner */
#ifdef ZTS
# define LANG_SCNG(v) ZEND_TSRMG_FAST(language_scanner_globals_offset, zend_php_scanner_globals *, v)
# define LANG_SCNG(v) ZEND_TSRMG_FAST(ZEND_SCNG_OFFSET, zend_php_scanner_globals *, v)
extern ZEND_API ts_rsrc_id language_scanner_globals_id;
extern ZEND_API size_t language_scanner_globals_offset;
#else
Expand Down
2 changes: 1 addition & 1 deletion Zend/zend_portability.h
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Expand Up @@ -862,7 +862,7 @@ extern "C++" {
/** @deprecated */
#define ZEND_CGG_DIAGNOSTIC_IGNORED_END ZEND_DIAGNOSTIC_IGNORED_END

#if defined(__cplusplus)
#if defined(__cplusplus) || defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 202311L)

@henderkes henderkes Jun 12, 2026

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technically unrelated, but I didn't want to copy an incomplete definition into tsrm.c

@TimWolla TimWolla Jun 12, 2026

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see also #21228.

@henderkes henderkes Jun 12, 2026

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I'd be in favour, getting php-src and extensions to compile in extremely old environments is a pain anyway (I do rhel-7 builds for frankenphp). Should I replace this then?

@TimWolla TimWolla Jun 12, 2026

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Should I replace this then?

Not yet, probably. See: https://news-web.php.net/php.internals/130714

# define ZEND_STATIC_ASSERT(c, m) static_assert((c), m)
#elif defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 201112L) /* C11 */
# define ZEND_STATIC_ASSERT(c, m) _Static_assert((c), m)
Expand Down
6 changes: 6 additions & 0 deletions main/main.c
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Expand Up @@ -2842,6 +2842,12 @@ PHPAPI bool php_tsrm_startup_ex(int expected_threads)
{
bool ret = tsrm_startup(expected_threads, 1, 0, NULL);
php_reserve_tsrm_memory();
/* Must reserve exactly the prefix laid out by ZEND_*_OFFSET (zend_globals.h). */
tsrm_reserve_fast_front(
TSRM_ALIGNED_SIZE(sizeof(zend_compiler_globals)) +
TSRM_ALIGNED_SIZE(sizeof(zend_executor_globals)) +
TSRM_ALIGNED_SIZE(sizeof(zend_php_scanner_globals)) +
TSRM_ALIGNED_SIZE(zend_mm_globals_size())); // AG size, exposed through function call

@henderkes henderkes Jun 12, 2026

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really unhappy about this, same issue as below:

(void)ts_resource(0);
return ret;
}
Expand Down
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