fix: Deduce textstart from runtime.text symbol or moduledata for Go 1.26#1146
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| const textStartOff = 22 * 8 | ||
| if textStartOff+8 > len(moduleData) { | ||
| return 0, fmt.Errorf("invalid text start offset: %v", textStartOff) | ||
| } | ||
| textStart = *(*uintptr)(unsafe.Pointer(&moduleData[textStartOff])) | ||
| return textStart, nil |
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For stripped Go 1.26 PIE/external-linked binaries (no runtime.text symbol), this falls back to reading moduledata.text directly from the .go.module section bytes. Those pointer fields are relocated at load time for ET_DYN/PIE, and Section.Data returns the raw on-disk contents without applying relocations, so the value is often 0 or otherwise unrelocated. That means textStart can remain wrong specifically for stripped PIE binaries, regressing unwinding compared to the old .text-section fallback. Consider resolving relocations for .go.module (or falling back to .text if the unrelocated value is 0) before using it.
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…the whole .go.module section into memory.
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| return 0, fmt.Errorf("could not read .go.module section at offset %v: %w", textOffset, err) | ||
| } | ||
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| return *(*uintptr)(unsafe.Pointer(&textBytes[0])), nil |
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For easier maintainability we could use the following instead.
| return *(*uintptr)(unsafe.Pointer(&textBytes[0])), nil | |
| return uintptr(binary.LittleEndian.Uint64(textBytes[:])), nil |
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I was hesitating to use binary since the rest of the file was using unsafe casts.
open-telemetry#1146 added new executables in testdata. Signed-off-by: Florian Lehner <florian.lehner@elastic.co>
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Fixes #1145
Starting from Go 1.26, textStart address in pclntab is always set to 0, currently address of
.textsection is used when textStart is 0, but that is not always correct (for example with cgo binaries or when built with -linkmode=external).The proposed change is to deduce textStart from either
runtime.textsymbol ormoduledata.textif there are not symbols.