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Link Here
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<title>How do I debug with gdb?</title> |
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<title>How do I debug with gdb?</title> |
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<body> |
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<body> |
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<p> |
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<p> |
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First gotcha is that GDB can't resolve symbols in PIEs; it doesn't realise that |
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First gotcha is that GDB versions before 7.1 can't resolve symbols in PIEs; it doesn't realise that |
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the addresses are relative in PIEs not absolute. This shows up when you try to |
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the addresses are relative in PIEs not absolute. This shows up when you try to |
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get a backtrace for example, and see a stream of lines with '??' where the |
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get a backtrace for example, and see a stream of lines with '??' where the |
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symbol should be. |
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symbol should be. |
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</p> |
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</p> |
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<p> |
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<p> |
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To get around this, do the final link stage with <c>-nopie</c> - all the |
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Although previous versions are patched to solve this, you can get around this if you do the final link stage with <c>-nopie</c> <c>-nopie</c> - all the |
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preceding object compilations can still be with <c>-fPIE</c> as normal (i.e. the |
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preceding object compilations can still be with <c>-fPIE</c> as normal (i.e. the |
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default with the hardened compiler) so that your executable is as close as |
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default with the hardened compiler) so that your executable is as close as |
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possible to the real thing, but the final link must create a regular executable. |
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possible to the real thing, but the final link must create a regular executable. |
