Remove opcache.consistency_checks

This feature has been broken at least since the tracing JIT and inheritance
cache have been introduced. The attempted fix (GH-10798) was too complex. We
have thus decided to remove this feature for now.

Closes GH-11832

Author: iluuu1994

UPGRADING

@@ -50,6 +50,15 @@ PHP 8.3 UPGRADE NOTES
   . C functions that have a return type of void now return null instead of
     returning the following object object(FFI\CData:void) { }
 
+- Opcache:
+  . The opcache.consistency_checks INI directive was removed. This feature was
+    broken with the tracing JIT, as well as with inheritance cache, and has been
+    disabled without a way to enable it since PHP 8.1.18 and PHP 8.2.5. Both the
+    tracing JIT and inheritance cache may modify shm after the script has been
+    persisted, invalidating its checksum. The attempted fix skipped over the
+    modifiable pointers but was rejected due to complexity. For this reason, it
+    was decided to remove the feature instead.
+
 - Standard:
   . The range() function has had various changes:
     * A TypeError is now thrown when passing objects, resources, or arrays

ext/opcache/ZendAccelerator.c

@@ -1538,8 +1538,6 @@ static zend_persistent_script *store_script_in_file_cache(zend_persistent_script
 			(size_t)ZCG(mem));
 	}
 
-	new_persistent_script->dynamic_members.checksum = zend_accel_script_checksum(new_persistent_script);
-
 	zend_file_cache_script_store(new_persistent_script, /* is_shm */ false);
 
 	return new_persistent_script;
@@ -1653,8 +1651,6 @@ static zend_persistent_script *cache_script_in_shared_memory(zend_persistent_scr
 			(size_t)ZCG(mem));
 	}
 
-	new_persistent_script->dynamic_members.checksum = zend_accel_script_checksum(new_persistent_script);
-
 	/* store script structure in the hash table */
 	bucket = zend_accel_hash_update(&ZCSG(hash), new_persistent_script->script.filename, 0, new_persistent_script);
 	if (bucket) {
@@ -2131,20 +2127,6 @@ zend_op_array *persistent_compile_file(zend_file_handle *file_handle, int type)
 		}
 	}
 
-	/* if turned on - check the compiled script ADLER32 checksum */
-	if (persistent_script && ZCG(accel_directives).consistency_checks
-		&& persistent_script->dynamic_members.hits % ZCG(accel_directives).consistency_checks == 0) {
-
-		unsigned int checksum = zend_accel_script_checksum(persistent_script);
-		if (checksum != persistent_script->dynamic_members.checksum ) {
-			/* The checksum is wrong */
-			zend_accel_error(ACCEL_LOG_INFO, "Checksum failed for '%s':  expected=0x%08x, found=0x%08x",
-							 ZSTR_VAL(persistent_script->script.filename), persistent_script->dynamic_members.checksum, checksum);
-			zend_accel_lock_discard_script(persistent_script);
-			persistent_script = NULL;
-		}
-	}
-
 	/* Check the second level cache */
 	if (!persistent_script && ZCG(accel_directives).file_cache) {
 		persistent_script = zend_file_cache_script_load(file_handle);
@@ -4280,8 +4262,6 @@ static zend_persistent_script* preload_script_in_shared_memory(zend_persistent_s
 			(size_t)ZCG(mem));
 	}
 
-	new_persistent_script->dynamic_members.checksum = zend_accel_script_checksum(new_persistent_script);
-
 	/* store script structure in the hash table */
 	bucket = zend_accel_hash_update(&ZCSG(hash), new_persistent_script->script.filename, 0, new_persistent_script);
 	if (bucket) {

ext/opcache/ZendAccelerator.h

@@ -132,14 +132,10 @@ typedef struct _zend_persistent_script {
 	void          *mem;                    /* shared memory area used by script structures */
 	size_t         size;                   /* size of used shared memory */
 
-	/* All entries that shouldn't be counted in the ADLER32
-	 * checksum must be declared in this struct
-	 */
 	struct zend_persistent_script_dynamic_members {
 		time_t       last_used;
 		zend_ulong   hits;
 		unsigned int memory_consumption;
-		unsigned int checksum;
 		time_t       revalidate;
 	} dynamic_members;
 } zend_persistent_script;
@@ -149,7 +145,6 @@ typedef struct _zend_accel_directives {
 	zend_long           max_accelerated_files;
 	double         max_wasted_percentage;
 	char          *user_blacklist_filename;
-	zend_long           consistency_checks;
 	zend_long           force_restart_timeout;
 	bool      use_cwd;
 	bool      ignore_dups;

ext/opcache/tests/gh8065.phpt

@@ -129,19 +129,6 @@ static ZEND_INI_MH(OnUpdateMaxWastedPercentage)
 	return SUCCESS;
 }
 
-static ZEND_INI_MH(OnUpdateConsistencyChecks)
-{
-	zend_long *p = (zend_long *) ZEND_INI_GET_ADDR();
-	zend_long consistency_checks = atoi(ZSTR_VAL(new_value));
-
-	if (consistency_checks != 0) {
-		zend_accel_error(ACCEL_LOG_WARNING, "opcache.consistency_checks is reset back to 0 because it does not work properly (see GH-8065, GH-10624).\n");
-		return FAILURE;
-	}
-	*p = 0;
-	return SUCCESS;
-}
-
 static ZEND_INI_MH(OnEnable)
 {
 	if (stage == ZEND_INI_STAGE_STARTUP ||
@@ -289,7 +276,6 @@ ZEND_INI_BEGIN()
 	STD_PHP_INI_ENTRY("opcache.interned_strings_buffer", "8"  , PHP_INI_SYSTEM, OnUpdateInternedStringsBuffer,	 accel_directives.interned_strings_buffer,   zend_accel_globals, accel_globals)
 	STD_PHP_INI_ENTRY("opcache.max_accelerated_files" , "10000", PHP_INI_SYSTEM, OnUpdateMaxAcceleratedFiles,	 accel_directives.max_accelerated_files,     zend_accel_globals, accel_globals)
 	STD_PHP_INI_ENTRY("opcache.max_wasted_percentage" , "5"   , PHP_INI_SYSTEM, OnUpdateMaxWastedPercentage,	 accel_directives.max_wasted_percentage,     zend_accel_globals, accel_globals)
-	STD_PHP_INI_ENTRY("opcache.consistency_checks"    , "0"   , PHP_INI_ALL   , OnUpdateConsistencyChecks,	     accel_directives.consistency_checks,        zend_accel_globals, accel_globals)
 	STD_PHP_INI_ENTRY("opcache.force_restart_timeout" , "180" , PHP_INI_SYSTEM, OnUpdateLong,	             accel_directives.force_restart_timeout,     zend_accel_globals, accel_globals)
 	STD_PHP_INI_ENTRY("opcache.revalidate_freq"       , "2"   , PHP_INI_ALL   , OnUpdateLong,	             accel_directives.revalidate_freq,           zend_accel_globals, accel_globals)
 	STD_PHP_INI_ENTRY("opcache.file_update_protection", "2"   , PHP_INI_ALL   , OnUpdateLong,                accel_directives.file_update_protection,    zend_accel_globals, accel_globals)
@@ -804,7 +790,6 @@ ZEND_FUNCTION(opcache_get_configuration)
 	add_assoc_long(&directives,	 "opcache.interned_strings_buffer",ZCG(accel_directives).interned_strings_buffer);
 	add_assoc_long(&directives, 	 "opcache.max_accelerated_files",  ZCG(accel_directives).max_accelerated_files);
 	add_assoc_double(&directives, "opcache.max_wasted_percentage",  ZCG(accel_directives).max_wasted_percentage);
-	add_assoc_long(&directives, 	 "opcache.consistency_checks",     ZCG(accel_directives).consistency_checks);
 	add_assoc_long(&directives, 	 "opcache.force_restart_timeout",  ZCG(accel_directives).force_restart_timeout);
 	add_assoc_long(&directives, 	 "opcache.revalidate_freq",        ZCG(accel_directives).revalidate_freq);
 	add_assoc_string(&directives, "opcache.preferred_memory_model", STRING_NOT_NULL(ZCG(accel_directives).memory_model));

ext/opcache/zend_accelerator_module.c

@@ -1936,7 +1936,6 @@ zend_persistent_script *zend_file_cache_script_load(zend_file_handle *file_handl
 
 	if (cache_it) {
 		ZCSG(map_ptr_last) = CG(map_ptr_last);
-		script->dynamic_members.checksum = zend_accel_script_checksum(script);
 		script->dynamic_members.last_used = ZCG(request_time);
 
 		zend_accel_hash_update(&ZCSG(hash), script->script.filename, 0, script);

ext/opcache/zend_file_cache.c

@@ -1841,10 +1841,6 @@ ldap.max_links = -1
 ; are cached.
 ;opcache.max_file_size=0
 
-; Check the cache checksum each N requests.
-; The default value of "0" means that the checks are disabled.
-;opcache.consistency_checks=0
-
 ; How long to wait (in seconds) for a scheduled restart to begin if the cache
 ; is not being accessed.
 ;opcache.force_restart_timeout=180

php.ini-development

@@ -1843,10 +1843,6 @@ ldap.max_links = -1
 ; are cached.
 ;opcache.max_file_size=0
 
-; Check the cache checksum each N requests.
-; The default value of "0" means that the checks are disabled.
-;opcache.consistency_checks=0
-
 ; How long to wait (in seconds) for a scheduled restart to begin if the cache
 ; is not being accessed.
 ;opcache.force_restart_timeout=180