feat(gotter)!: add fn to hook symbol but exclude self by gyuheon0h · Pull Request #2312 · DataDog/libdatadog

gyuheon0h · 2026-08-04T13:33:10Z

Stacked above feat(got-hook)!: add DT_HASH fallback, relocation type guard, and hook_symbol

PROF-15630

What does this PR do?

PHP needs to be able to hook libs and bins but skip its own exported fn.

Motivation

What inspired you to submit this pull request?

Additional Notes

Anything else we should know when reviewing?

How to test the change?

Describe here in detail how the change can be validated.

gyuheon0h · 2026-08-04T13:33:28Z

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
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feat(gotter)!: add fn to hook symbol but exclude self #2312 👈 (View in Graphite)
feat(gotter)!: add DT_HASH fallback, relocation type guard, and hook_symbol #2297 : 1 other dependent PR (#2268 )
refactor(got-patching): extract shared GOT-patching primitives into libdd-got-hook #2282
main

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github-actions · 2026-08-04T13:34:52Z

📚 Documentation Check Results

⚠️ 6 documentation warning(s) found

📦 `libdd-gotter` - 6 warning(s)

Updated: 2026-08-05 20:49:41 UTC | Commit: 72de605 | missing-docs job results

github-actions · 2026-08-04T13:36:34Z

🔒 Cargo Deny Results

✅ No issues found!

📦 `libdd-gotter` - ✅ No issues

Updated: 2026-08-05 20:51:50 UTC | Commit: 72de605 | dependency-check job results

datadog-prod-us1-6 · 2026-08-04T13:47:47Z

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

🎯 Code Coverage (details)
• Patch Coverage: 54.88%
• Overall Coverage: 75.01% (-0.14%)

_{This comment will be updated automatically if new data arrives.

🔗 Commit SHA: 520be6b | Docs | Datadog PR Page | Give us feedback!}

pr-commenter · 2026-08-04T14:14:49Z

Benchmarks

Comparison

Benchmark execution time: 2026-08-05 21:22:38

Comparing candidate commit 520be6b in PR branch gyuheon0h/got-hook-exclude-self with baseline commit e9568ee in branch gyuheon0h/got-hook-utils.

Found 0 performance improvements and 2 performance regressions! Performance is the same for 138 metrics, 0 unstable metrics.

Explanation

This is an A/B test comparing a candidate commit's performance against that of a baseline commit. Performance changes are noted in the tables below as:

🟩 = significantly better candidate vs. baseline
🟥 = significantly worse candidate vs. baseline

We compute a confidence interval (CI) over the relative difference of means between metrics from the candidate and baseline commits, considering the baseline as the reference.

If the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD), the change is considered significant.

Feel free to reach out to #apm-benchmarking-platform on Slack if you have any questions.

More details about the CI and significant changes

You can imagine this CI as a range of values that is likely to contain the true difference of means between the candidate and baseline commits.

CIs of the difference of means are often centered around 0%, because often changes are not that big:

---------------------------------(------|---^--------)-------------------------------->
                              -0.6%    0%  0.3%     +1.2%
                                 |          |        |
         lower bound of the CI --'          |        |
sample mean (center of the CI) -------------'        |
         upper bound of the CI ----------------------'

As described above, a change is considered significant if the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD).

For instance, for an execution time metric, this confidence interval indicates a significantly worse performance:

----------------------------------------|---------|---(---------^---------)---------->
                                       0%        1%  1.3%      2.2%      3.1%
                                                  |   |         |         |
       significant impact threshold --------------'   |         |         |
                      lower bound of CI --------------'         |         |
       sample mean (center of the CI) --------------------------'         |
                      upper bound of CI ----------------------------------'

scenario:profiles_dictionary/profile_string_inserts/threads/1

🟥 execution_time [+15.021µs; +16.707µs] or [+4.882%; +5.430%]
🟥 throughput [-172145.936op/s; -154284.467op/s] or [-5.172%; -4.636%]

Benchmark execution time: 2026-08-05 21:32:42

Comparing candidate commit 520be6b in PR branch gyuheon0h/got-hook-exclude-self with baseline commit e9568ee in branch gyuheon0h/got-hook-utils.

Found 6 performance improvements and 2 performance regressions! Performance is the same for 160 metrics, 10 unstable metrics.

Explanation

This is an A/B test comparing a candidate commit's performance against that of a baseline commit. Performance changes are noted in the tables below as:

🟩 = significantly better candidate vs. baseline
🟥 = significantly worse candidate vs. baseline

We compute a confidence interval (CI) over the relative difference of means between metrics from the candidate and baseline commits, considering the baseline as the reference.

If the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD), the change is considered significant.

Feel free to reach out to #apm-benchmarking-platform on Slack if you have any questions.

More details about the CI and significant changes

You can imagine this CI as a range of values that is likely to contain the true difference of means between the candidate and baseline commits.

CIs of the difference of means are often centered around 0%, because often changes are not that big:

---------------------------------(------|---^--------)-------------------------------->
                              -0.6%    0%  0.3%     +1.2%
                                 |          |        |
         lower bound of the CI --'          |        |
sample mean (center of the CI) -------------'        |
         upper bound of the CI ----------------------'

As described above, a change is considered significant if the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD).

For instance, for an execution time metric, this confidence interval indicates a significantly worse performance:

----------------------------------------|---------|---(---------^---------)---------->
                                       0%        1%  1.3%      2.2%      3.1%
                                                  |   |         |         |
       significant impact threshold --------------'   |         |         |
                      lower bound of CI --------------'         |         |
       sample mean (center of the CI) --------------------------'         |
                      upper bound of CI ----------------------------------'

scenario:datadog_sample_span/multiple_rules_last_match/wall_time

🟥 execution_time [+15.979ns; +16.089ns] or [+8.004%; +8.059%]

scenario:glob_matcher/ascii_wildcard_question_match/wall_time

🟥 execution_time [+1.620ns; +1.636ns] or [+4.384%; +4.426%]

scenario:profiler_attached/fast_path_system/4096

🟩 execution_time [-25.977ns; -25.844ns] or [-24.895%; -24.767%]

scenario:profiler_attached/slow_path_system/4096

🟩 execution_time [-16.735ns; -16.558ns] or [-10.847%; -10.733%]

scenario:trace_buffer/2_senders/no_delay

🟩 execution_time [-145.788µs; -131.234µs] or [-8.764%; -7.889%]
🟩 throughput [+92925.677op/s; +103040.834op/s] or [+8.582%; +9.516%]

scenario:trace_buffer/4_senders/no_delay

🟩 execution_time [-165.547µs; -153.848µs] or [-4.325%; -4.019%]
🟩 throughput [+39470.512op/s; +42467.685op/s] or [+4.196%; +4.515%]

Candidate

Omitted due to size.

Baseline

Omitted due to size.

dd-octo-sts · 2026-08-04T15:19:48Z

Artifact Size Benchmark Report

aarch64-alpine-linux-musl

Artifact	Baseline	Commit	Change
/aarch64-alpine-linux-musl/lib/libdatadog_profiling.a	87.84 MB	87.84 MB	0% (0 B) 👌
/aarch64-alpine-linux-musl/lib/libdatadog_profiling.so	8.07 MB	8.07 MB	0% (0 B) 👌

aarch64-unknown-linux-gnu

Artifact	Baseline	Commit	Change
/aarch64-unknown-linux-gnu/lib/libdatadog_profiling.so	10.88 MB	10.88 MB	0% (0 B) 👌
/aarch64-unknown-linux-gnu/lib/libdatadog_profiling.a	98.97 MB	98.97 MB	0% (0 B) 👌

libdatadog-x64-windows

Artifact	Baseline	Commit	Change
/libdatadog-x64-windows/debug/dynamic/datadog_profiling_ffi.dll	26.21 MB	26.21 MB	0% (0 B) 👌
/libdatadog-x64-windows/debug/dynamic/datadog_profiling_ffi.lib	89.92 KB	89.92 KB	0% (0 B) 👌
/libdatadog-x64-windows/debug/dynamic/datadog_profiling_ffi.pdb	188.66 MB	188.66 MB	+0% (+8.00 KB) 👌
/libdatadog-x64-windows/debug/static/datadog_profiling_ffi.lib	985.57 MB	985.57 MB	0% (0 B) 👌
/libdatadog-x64-windows/release/dynamic/datadog_profiling_ffi.dll	8.56 MB	8.56 MB	0% (0 B) 👌
/libdatadog-x64-windows/release/dynamic/datadog_profiling_ffi.lib	89.92 KB	89.92 KB	0% (0 B) 👌
/libdatadog-x64-windows/release/dynamic/datadog_profiling_ffi.pdb	25.22 MB	25.22 MB	0% (0 B) 👌
/libdatadog-x64-windows/release/static/datadog_profiling_ffi.lib	50.23 MB	50.23 MB	0% (0 B) 👌

libdatadog-x86-windows

Artifact	Baseline	Commit	Change
/libdatadog-x86-windows/debug/dynamic/datadog_profiling_ffi.dll	22.84 MB	22.84 MB	0% (0 B) 👌
/libdatadog-x86-windows/debug/dynamic/datadog_profiling_ffi.lib	91.33 KB	91.33 KB	0% (0 B) 👌
/libdatadog-x86-windows/debug/dynamic/datadog_profiling_ffi.pdb	193.44 MB	193.44 MB	0% (0 B) 👌
/libdatadog-x86-windows/debug/static/datadog_profiling_ffi.lib	974.34 MB	974.34 MB	0% (0 B) 👌
/libdatadog-x86-windows/release/dynamic/datadog_profiling_ffi.dll	6.61 MB	6.61 MB	0% (0 B) 👌
/libdatadog-x86-windows/release/dynamic/datadog_profiling_ffi.lib	91.33 KB	91.33 KB	0% (0 B) 👌
/libdatadog-x86-windows/release/dynamic/datadog_profiling_ffi.pdb	27.12 MB	27.12 MB	0% (0 B) 👌
/libdatadog-x86-windows/release/static/datadog_profiling_ffi.lib	47.83 MB	47.83 MB	0% (0 B) 👌

x86_64-alpine-linux-musl

Artifact	Baseline	Commit	Change
/x86_64-alpine-linux-musl/lib/libdatadog_profiling.a	78.21 MB	78.21 MB	0% (0 B) 👌
/x86_64-alpine-linux-musl/lib/libdatadog_profiling.so	9.00 MB	9.00 MB	0% (0 B) 👌

x86_64-unknown-linux-gnu

Artifact	Baseline	Commit	Change
/x86_64-unknown-linux-gnu/lib/libdatadog_profiling.a	93.85 MB	93.85 MB	0% (0 B) 👌
/x86_64-unknown-linux-gnu/lib/libdatadog_profiling.so	10.97 MB	10.97 MB	0% (0 B) 👌

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chatgpt-codex-connector · 2026-08-04T15:32:35Z

+
+        // Skip the hook's own library if requested.
+        if let Some(base) = skip_base {
+            if info.dlpi_addr as usize == base {


Handle non-PIE executables when skipping self

When hook_fn lives in a non-PIE main executable, dl_iterate_phdr reports the executable's dlpi_addr as 0 while dladdr(...).dli_fbase is the executable's load base, so this equality never matches and hook_symbol_excluding_self still patches the binary that contains the hook. In that context the hook's own executable can have its GOT entries redirected back to the hook, leading to recursion or crashes; please compare against the object's actual mapped range/PHDR base rather than dlpi_addr alone.

AGENTS.md reference: AGENTS.md:L70-L71

Useful? React with 👍 / 👎.

Not sure if this is common enough to do. Php tracer's GOT patching doesn't seem to care for this. WDYT @realFlowControl

Non-PIE executables are uncommon but still in use; we should handle this.

Got it. Im gonna be honest, I am not familiar with PIE, but I came to this commit: 520be6b off of reading https://one2bla.me/the-dark-arts/exploit-mitigations/position-independent-executables.html and some stack overflow blogs, with the help of my buddy claude.

Would appreciate special review over the above commit. Thanks :D

gyuheon0h mentioned this pull request Aug 4, 2026

feat(crashtracking)!: retrieve c assert message for linux when __assert_fail is dynamically loaded #2268

Draft

gyuheon0h changed the title ~~Add fn to hook but exclude self~~ feat(gotter): add fn to hook but exclude self Aug 4, 2026

gyuheon0h mentioned this pull request Aug 4, 2026

refactor(got-patching): extract shared GOT-patching primitives into libdd-got-hook #2282

Merged

gyuheon0h mentioned this pull request Aug 4, 2026

feat(gotter)!: add DT_HASH fallback, relocation type guard, and hook_symbol #2297

Open

gyuheon0h force-pushed the gyuheon0h/got-hook-exclude-self branch from 0c7b004 to 7248198 Compare August 4, 2026 13:34

gyuheon0h changed the title ~~feat(gotter): add fn to hook but exclude self~~ feat(gotter): add fn to hook symbol but exclude self Aug 4, 2026

gyuheon0h force-pushed the gyuheon0h/got-hook-exclude-self branch 2 times, most recently from 05b1bde to 92dd335 Compare August 4, 2026 14:12

gyuheon0h force-pushed the gyuheon0h/got-hook-utils branch from a4a6346 to 9d4d601 Compare August 4, 2026 14:12

gyuheon0h force-pushed the gyuheon0h/got-hook-utils branch from 9d4d601 to f19c984 Compare August 4, 2026 14:36

gyuheon0h force-pushed the gyuheon0h/got-hook-exclude-self branch from 92dd335 to 0b9de90 Compare August 4, 2026 14:36

gyuheon0h changed the title ~~feat(gotter): add fn to hook symbol but exclude self~~ feat(gotter)!: add fn to hook symbol but exclude self Aug 4, 2026

gyuheon0h marked this pull request as ready for review August 4, 2026 15:23

gyuheon0h requested review from a team as code owners August 4, 2026 15:23

chatgpt-codex-connector Bot reviewed Aug 4, 2026

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gyuheon0h marked this pull request as draft August 4, 2026 15:33

gyuheon0h marked this pull request as ready for review August 4, 2026 15:53

gyuheon0h requested a review from realFlowControl August 4, 2026 15:53

gyuheon0h force-pushed the gyuheon0h/got-hook-exclude-self branch 3 times, most recently from 72c1fe9 to 65852e6 Compare August 4, 2026 18:15

scottgerring reviewed Aug 5, 2026

View reviewed changes

Comment thread libdd-gotter/src/elf.rs

gyuheon0h force-pushed the gyuheon0h/got-hook-exclude-self branch from 74f89d5 to fd11980 Compare August 5, 2026 20:26

gyuheon0h added 5 commits August 5, 2026 20:47

Add fn to hook but exclude self

60b62fe

Test that skip works

74eaa97

exclude self while resolving original

0b9b6a0

Add some more detail and context on these APIs

b05e7fe

non PIE executable support

520be6b

gyuheon0h force-pushed the gyuheon0h/got-hook-utils branch from 2d9bca3 to e9568ee Compare August 5, 2026 20:47

gyuheon0h force-pushed the gyuheon0h/got-hook-exclude-self branch from fd11980 to 520be6b Compare August 5, 2026 20:47

gyuheon0h requested a review from scottgerring August 5, 2026 20:48

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What does this PR do?

Motivation

Additional Notes

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gyuheon0h commented Aug 4, 2026

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📚 Documentation Check Results

📦 libdd-gotter - 6 warning(s)

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🔒 Cargo Deny Results

📦 libdd-gotter - ✅ No issues

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Benchmarks

Comparison

Explanation

More details about the CI and significant changes

scenario:profiles_dictionary/profile_string_inserts/threads/1

Explanation

More details about the CI and significant changes

scenario:datadog_sample_span/multiple_rules_last_match/wall_time

scenario:glob_matcher/ascii_wildcard_question_match/wall_time

scenario:profiler_attached/fast_path_system/4096

scenario:profiler_attached/slow_path_system/4096

scenario:trace_buffer/2_senders/no_delay

scenario:trace_buffer/4_senders/no_delay

Candidate

Baseline

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Artifact Size Benchmark Report

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gyuheon0h commented Aug 4, 2026 •

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📦 `libdd-gotter` - 6 warning(s)

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📦 `libdd-gotter` - ✅ No issues

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