uprobes: automatic resolution of library paths #1971
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Does this also work for libraries that are dlopened? |
The library paths are searched for in |
docs/reference_guide.md
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| When tracing libraries, it is sufficient to specify the library name instead of | ||
| a full path. |
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Maybe also mention the lookup is done via ldcache? This may be important for systems that have multiple versions of a library installed.
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dont forget to mirror this to the manpage too
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Good points. Updated, please check.
tests/runtime/engine/parser.py
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| @@ -115,7 +115,7 @@ def __read_test_struct(test, test_suite): | |||
| elif item_name == 'ARCH': | |||
| arch = [x.strip() for x in line.split("|")] | |||
| elif item_name == 'REQUIRES_FEATURE': | |||
| features = {"loop", "btf", "probe_read_kernel", "dpath", "uprobe_refcount", "signal", "iter:task", "iter:task_file"} | |||
| features = {"loop", "btf", "probe_read_kernel", "dpath", "uprobe_refcount", "signal", "iter:task", "iter:task_file", "libpath_resolv"} | |||
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Could you break this up into multiple lines, please?
tests/runtime/probe
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| RUN {{BPFTRACE}} -e 'uprobe:libc:write { printf("size: %d\n", arg0); exit(); }' | ||
| EXPECT size: [0-9]+ | ||
| TIMEOUT 5 | ||
| AFTER cat /etc/passwd > /dev/null |
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Can you write a testprog for this instead? Don't want this test to flake out on us in the future if cat changes.
Uses BCC to resolve a library name into its full path. We require that the library XXX is specified in the form "libXXX". Example: "uprobe:libc:malloc".
Since automatic resolution depends on a BCC capability, a new feature had to be added to the runtime tests framework. Also, embedded Alpine builds do not have a shared libc so we must disable the new test for them.
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This introduces an option to attach to library functions by specifying just the library name instead of a full path. For example:
One of the use-cases is a better portability of scripts that attach to library functions (as the full library paths may differ across systems). For example, the current
tools/gethostlatency.btdoesn't work on Fedora.Unfortunately, our shipped tools cannot be updated right away since this feature relies on BCC's
bcc_procutils_which_sowhich is not available on old BCC versions, especially not those used in the CI. If #1933 was resolved, it would be possible.Checklist
man/adoc/bpftrace.adocand if needed indocs/reference_guide.mdCHANGELOG.md