fix(prof): disable allocation profiling when JIT is enabled on PHP 8.4

profiling/src/allocation/allocation_ge84.rs

@@ -3,8 +3,9 @@ use crate::allocation::ALLOCATION_PROFILING_SIZE;
 use crate::allocation::ALLOCATION_PROFILING_STATS;
 use crate::bindings::{self as zend};
 use crate::PROFILER_NAME;
+use lazy_static::lazy_static;
 use libc::{c_char, c_void, size_t};
-use log::{debug, trace, warn};
+use log::{debug, error, trace, warn};
 use std::cell::UnsafeCell;
 use std::ptr;
 use std::sync::atomic::Ordering::SeqCst;
@@ -95,12 +96,26 @@ macro_rules! tls_zend_mm_state {
     };
 }
 
+lazy_static! {
+    static ref JIT_ENABLED: bool = unsafe { zend::ddog_php_jit_enabled() };
+}
+
+pub fn first_rinit_should_disable_due_to_jit() -> bool {
+    if *JIT_ENABLED && zend::PHP_VERSION_ID >= 80400 {
+        error!("Memory allocation profiling will be disabled as long as JIT is active. To enable allocation profiling disable JIT. See https://github.com/DataDog/dd-trace-php/pull/3199");
+        true
+    } else {
+        false
+    }
+}
+
 /// This initializes the thread locale variable `ZEND_MM_STATE` with respect to the currently
 /// installed `zend_mm_heap` in ZendMM. It guarantees compliance with the safety guarantees
 /// described in the `ZendMMState` structure, specifically for `ZendMMState::alloc`,
 /// `ZendMMState::realloc`, `ZendMMState::free`, `ZendMMState::gc` and `ZendMMState::shutdown`.
 /// This function may panic if called out of order!
 pub fn alloc_prof_ginit() {
+    unsafe { zend::ddog_php_opcache_init_handle() };
     ZEND_MM_STATE.with(|cell| {
         let zend_mm_state = cell.get();
 

profiling/src/allocation/mod.rs

@@ -9,7 +9,7 @@ use std::cell::RefCell;
 use std::sync::atomic::AtomicU64;
 
 #[cfg(php_zend_mm_set_custom_handlers_ex)]
-mod allocation_ge84;
+pub mod allocation_ge84;
 #[cfg(not(php_zend_mm_set_custom_handlers_ex))]
 pub mod allocation_le83;
 

profiling/src/config.rs

@@ -1,4 +1,3 @@
-#[cfg(not(php_zend_mm_set_custom_handlers_ex))]
 use crate::allocation;
 use crate::bindings::zai_config_type::*;
 use crate::bindings::{
@@ -113,6 +112,10 @@ impl SystemSettings {
         if allocation::allocation_le83::first_rinit_should_disable_due_to_jit() {
             system_settings.profiling_allocation_enabled = false;
         }
+        #[cfg(php_zend_mm_set_custom_handlers_ex)]
+        if allocation::allocation_ge84::first_rinit_should_disable_due_to_jit() {
+            system_settings.profiling_allocation_enabled = false;
+        }
         swap(&mut system_settings, SYSTEM_SETTINGS.assume_init_mut());
     }
 

profiling/src/lib.rs

@@ -791,7 +791,12 @@ unsafe extern "C" fn minfo(module_ptr: *mut zend::ModuleEntry) {
                     if system_settings.profiling_allocation_enabled {
                         yes
                     } else if zend::ddog_php_jit_enabled() {
-                        b"Not available due to JIT being active, see https://github.com/DataDog/dd-trace-php/pull/2088 for more information.\0"
+                        // Work around version-specific issues.
+                        if cfg!(not(php_zend_mm_set_custom_handlers_ex)) {
+                            b"Not available due to JIT being active, see https://github.com/DataDog/dd-trace-php/pull/2088 for more information.\0"
+                        } else {
+                            b"Not available due to JIT being active, see https://github.com/DataDog/dd-trace-php/pull/3199 for more information.\0"
+                        }
                     } else if system_settings.profiling_enabled {
                         no
                     } else {

profiling/tests/phpt/jit_01.phpt

@@ -10,6 +10,8 @@ if (PHP_VERSION_ID >= 80208 || PHP_VERSION_ID >= 80121 && PHP_VERSION_ID < 80200
     echo "skip: PHP Version >= 8.1.21 and >= 8.2.8 have a fix for this";
 if (PHP_VERSION_ID < 80000)
     echo "skip: JIT requires PHP >= 8.0", PHP_EOL;
+if (PHP_VERSION_ID >= 80300)
+    echo "skip: not affected version", PHP_EOL;
 if (!extension_loaded('datadog-profiling'))
     echo "skip: test requires datadog-profiling", PHP_EOL;
 $arch = php_uname('m');

profiling/tests/phpt/jit_02.phpt

@@ -9,6 +9,8 @@ if (PHP_VERSION_ID < 80120 || PHP_VERSION_ID >= 80200 && PHP_VERSION_ID < 80207)
     echo "skip: unpatched PHP version, so JIT should be inactive";
 if (PHP_VERSION_ID < 80000)
     echo "skip: JIT requires PHP >= 8.0", PHP_EOL;
+if (PHP_VERSION_ID >= 80300)
+    echo "skip: not affected version", PHP_EOL;
 if (!extension_loaded('datadog-profiling'))
     echo "skip: test requires datadog-profiling", PHP_EOL;
 $arch = php_uname('m');

profiling/tests/phpt/jit_03.phpt

@@ -0,0 +1,29 @@
+--TEST--
+[profiling] Allocation profiling should be disabled when JIT is active on PHP 8.4
+--DESCRIPTION--
+We did find a crash in PHP when collecting a stack sample in allocation
+profiling when JIT is activated while a function becomes hot. For the time being
+we make sure to disable allocation profiling when we detect the JIT is enabled.
+--SKIPIF--
+<?php
+if (PHP_VERSION_ID < 80400)
+    echo "skip: PHP Version < 8.4 are not affected", PHP_EOL;
+if (!extension_loaded('datadog-profiling'))
+    echo "skip: test requires datadog-profiling", PHP_EOL;
+?>
+--INI--
+datadog.profiling.enabled=yes
+datadog.profiling.log_level=debug
+datadog.profiling.allocation_enabled=yes
+datadog.profiling.experimental_cpu_time_enabled=no
+zend_extension=opcache
+opcache.enable_cli=1
+opcache.jit=tracing
+opcache.jit_buffer_size=4M
+--FILE--
+<?php
+echo "Done.", PHP_EOL;
+?>
+--EXPECTF--
+%aMemory allocation profiling will be disabled as long as JIT is active. To enable allocation profiling disable JIT. See https://github.com/DataDog/dd-trace-php/pull/3199
+%ADone.%a

profiling/tests/phpt/phpinfo_04.phpt

@@ -5,7 +5,7 @@ The profiler's phpinfo section contains important debugging information. This
 test verifies that certain information is present.
 --SKIPIF--
 <?php
-if (PHP_VERSION_ID < 80120 || PHP_VERSION_ID >= 80200 && PHP_VERSION_ID < 80207)
+if (PHP_VERSION_ID < 80120 || PHP_VERSION_ID >= 80200 && PHP_VERSION_ID < 80207 || PHP_VERSION_ID >= 80400)
     echo "skip: unpatched PHP version, so JIT should be inactive";
 if (PHP_VERSION_ID < 80000)
     echo "skip: JIT requires PHP >= 8.0", PHP_EOL;