ExecSolib strategy: make ddtrace.so directly executable

[cataphract]

Introduce the ExecSolib spawn strategy by embedding an ELF entry point (_dd_solib_start) into ddtrace.so itself.

ddtrace.so becomes pie executable and runs without the dynamic linker. After self-relocation:

• it loads the trampoline into memory, but doesn't execute it yet
• it copies ddtrace.so (/proc/self/exe) into a memfd and massages it so its loading by the dynamic linker without php doesn't fail.
• replaces in the command line all occurrences to ddtrace.so to /proc/self/fd/, so that dlopen from the trampoline will use the massaged version
• loads the dynamic linker into memory
• jumps into the dynamic linker after massaging the auxiliary vector so that ld.so executes the loaded trampoline

tested on glibc and musl on linux aarch64

Description

Reviewer checklist

• Test coverage seems ok.
• Appropriate labels assigned.

[datadog-datadog-prod-us1]

⚠️ Tests

✨ Fix all issues with BitsAI or with Cursor

⚠️ Warnings

🧪 1049 Tests failed

initializationError from com.datadog.appsec.php.integration.RemoteConfigTests     (Fix with Cursor)

java.lang.AssertionError: No request with version 0 gotten within 12000 ms for com.datadog.appsec.php.mock_agent.rem_cfg.Target(some-name, none, )

java.lang.AssertionError: No request with version 0 gotten within 12000 ms for com.datadog.appsec.php.mock_agent.rem_cfg.Target(some-name, none, )
	at com.datadog.appsec.php.mock_agent.ConfigV07Handler.waitForVersion(ConfigV07Handler.groovy:72)
	at com.datadog.appsec.php.mock_agent.MockDatadogAgent.waitForRCVersion(MockDatadogAgent.groovy:80)
	at com.datadog.appsec.php.docker.AppSecContainer.waitForRCVersion(AppSecContainer.groovy:184)
	at org.codehaus.groovy.vmplugin.v8.IndyInterface.fromCache(IndyInterface.java:321)
	at com.datadog.appsec.php.integration.RemoteConfigTests.beforeAll(RemoteConfigTests.groovy:56)
	at java.base/java.lang.reflect.Method.invoke(Method.java:569)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)

testSearchPhpBinaries from integration.DDTrace\Tests\Integration\PHPInstallerTest     (Fix with Cursor)

Risky Test
phpvfscomposer://tests/vendor/phpunit/phpunit/phpunit:52

testSimplePushAndProcess from laravel-58-test.DDTrace\Tests\Integrations\Laravel\V5_8\QueueTest     (Fix with Cursor)

Risky Test
phpvfscomposer://tests/vendor/phpunit/phpunit/phpunit:97

View all

ℹ️ Info

No other issues found (see more)

❄️ No new flaky tests detected

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 86db928 | Docs | Datadog PR Page | Was this helpful? React with 👍/👎 or give us feedback!}

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 68.73%. Comparing base (b9a49fa) to head (86db928).
⚠️ Report is 12 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3711      +/-   ##
==========================================
- Coverage   68.77%   68.73%   -0.04%     
==========================================
  Files         166      166              
  Lines       19030    19030              
  Branches     1797     1797              
==========================================
- Hits        13087    13080       -7     
- Misses       5127     5135       +8     
+ Partials      816      815       -1     

Flag	Coverage Δ
helper-rust-integration	78.82% <ø> (-0.03%)	⬇️
helper-rust-unit	49.36% <ø> (-0.08%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.
see 3 files with indirect coverage changes

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[pr-commenter]

Benchmarks [ tracer ]

Benchmark execution time: 2026-03-22 03:32:20

Comparing candidate commit 9293858 in PR branch glopes/exec-solib with baseline commit b9a49fa in branch master.

Found 0 performance improvements and 1 performance regressions! Performance is the same for 192 metrics, 1 unstable metrics.

scenario:MessagePackSerializationBench/benchMessagePackSerialization-opcache

• 🟥 execution_time [+3.391µs; +4.449µs] or [+3.050%; +4.001%]