81 lines
3.0 KiB
Bash
81 lines
3.0 KiB
Bash
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# Copyright © 2016 IBM Corporation
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# This program is free software; you can redistribute it and/or
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# modify it under the terms of the GNU General Public License
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# as published by the Free Software Foundation; either version
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# 2 of the License, or (at your option) any later version.
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# This script checks the head of a vmlinux for linker stubs that
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# break our placement of fixed-location code for 64-bit.
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# based on relocs_check.pl
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# Copyright © 2009 IBM Corporation
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# NOTE!
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#
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# If the build dies here, it's likely code in head_64.S/exception-64*.S or
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# nearby, is branching to labels it can't reach directly, which results in the
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# linker inserting branch stubs. This can move code around in ways that break
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# the fixed section calculations (head-64.h). To debug this, disassemble the
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# vmlinux and look for branch stubs (long_branch, plt_branch, etc.) in the
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# fixed section region (0 - 0x8000ish). Check what code is calling those stubs,
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# and perhaps change so a direct branch can reach.
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#
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# A ".linker_stub_catch" section is used to catch some stubs generated by
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# early .text code, which tend to get placed at the start of the section.
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# If there are too many such stubs, they can overflow this section. Expanding
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# it may help (or reducing the number of stub branches).
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#
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# Linker stubs use the TOC pointer, so even if fixed section code could
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# tolerate them being inserted into head code, they can't be allowed in low
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# level entry code (boot, interrupt vectors, etc) until r2 is set up. This
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# could cause the kernel to die in early boot.
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# Allow for verbose output
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if [ "$V" = "1" ]; then
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set -x
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fi
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if [ $# -lt 2 ]; then
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echo "$0 [path to nm] [path to vmlinux]" 1>&2
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exit 1
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fi
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# Have Kbuild supply the path to nm so we handle cross compilation.
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nm="$1"
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vmlinux="$2"
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# gcc-4.6-era toolchain make _stext an A (absolute) symbol rather than T
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$nm "$vmlinux" | grep -e " [TA] _stext$" -e " t start_first_256B$" -e " a text_start$" -e " t start_text$" > .tmp_symbols.txt
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vma=$(grep -e " [TA] _stext$" .tmp_symbols.txt | cut -d' ' -f1)
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expected_start_head_addr="$vma"
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start_head_addr=$(grep " t start_first_256B$" .tmp_symbols.txt | cut -d' ' -f1)
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if [ "$start_head_addr" != "$expected_start_head_addr" ]; then
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echo "ERROR: head code starts at $start_head_addr, should be $expected_start_head_addr" 1>&2
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echo "ERROR: try to enable LD_HEAD_STUB_CATCH config option" 1>&2
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echo "ERROR: see comments in arch/powerpc/tools/head_check.sh" 1>&2
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exit 1
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fi
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top_vma=$(echo "$vma" | cut -d'0' -f1)
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expected_start_text_addr=$(grep " a text_start$" .tmp_symbols.txt | cut -d' ' -f1 | sed "s/^0/$top_vma/")
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start_text_addr=$(grep " t start_text$" .tmp_symbols.txt | cut -d' ' -f1)
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if [ "$start_text_addr" != "$expected_start_text_addr" ]; then
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echo "ERROR: start_text address is $start_text_addr, should be $expected_start_text_addr" 1>&2
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echo "ERROR: try to enable LD_HEAD_STUB_CATCH config option" 1>&2
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echo "ERROR: see comments in arch/powerpc/tools/head_check.sh" 1>&2
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exit 1
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fi
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rm -f .tmp_symbols.txt
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