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Diffstat (limited to 'arch/powerpc/tools/head_check.sh')
| -rw-r--r-- | arch/powerpc/tools/head_check.sh | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/arch/powerpc/tools/head_check.sh b/arch/powerpc/tools/head_check.sh new file mode 100644 index 0000000000..689907cda9 --- /dev/null +++ b/arch/powerpc/tools/head_check.sh @@ -0,0 +1,80 @@ +# Copyright © 2016 IBM Corporation + +# This program is free software; you can redistribute it and/or +# modify it under the terms of the GNU General Public License +# as published by the Free Software Foundation; either version +# 2 of the License, or (at your option) any later version. + +# This script checks the head of a vmlinux for linker stubs that +# break our placement of fixed-location code for 64-bit. + +# based on relocs_check.pl +# Copyright © 2009 IBM Corporation + +# NOTE! +# +# If the build dies here, it's likely code in head_64.S/exception-64*.S or +# nearby, is branching to labels it can't reach directly, which results in the +# linker inserting branch stubs. This can move code around in ways that break +# the fixed section calculations (head-64.h). To debug this, disassemble the +# vmlinux and look for branch stubs (long_branch, plt_branch, etc.) in the +# fixed section region (0 - 0x8000ish). Check what code is calling those stubs, +# and perhaps change so a direct branch can reach. +# +# A ".linker_stub_catch" section is used to catch some stubs generated by +# early .text code, which tend to get placed at the start of the section. +# If there are too many such stubs, they can overflow this section. Expanding +# it may help (or reducing the number of stub branches). +# +# Linker stubs use the TOC pointer, so even if fixed section code could +# tolerate them being inserted into head code, they can't be allowed in low +# level entry code (boot, interrupt vectors, etc) until r2 is set up. This +# could cause the kernel to die in early boot. + +# Allow for verbose output +if [ "$V" = "1" ]; then + set -x +fi + +if [ $# -lt 2 ]; then + echo "$0 [path to nm] [path to vmlinux]" 1>&2 + exit 1 +fi + +# Have Kbuild supply the path to nm so we handle cross compilation. +nm="$1" +vmlinux="$2" + +# gcc-4.6-era toolchain make _stext an A (absolute) symbol rather than T +$nm "$vmlinux" | grep -e " [TA] _stext$" -e " t start_first_256B$" -e " a text_start$" -e " t start_text$" > .tmp_symbols.txt + + +vma=$(grep -e " [TA] _stext$" .tmp_symbols.txt | cut -d' ' -f1) + +expected_start_head_addr="$vma" + +start_head_addr=$(grep " t start_first_256B$" .tmp_symbols.txt | cut -d' ' -f1) + +if [ "$start_head_addr" != "$expected_start_head_addr" ]; then + echo "ERROR: head code starts at $start_head_addr, should be $expected_start_head_addr" 1>&2 + echo "ERROR: try to enable LD_HEAD_STUB_CATCH config option" 1>&2 + echo "ERROR: see comments in arch/powerpc/tools/head_check.sh" 1>&2 + + exit 1 +fi + +top_vma=$(echo "$vma" | cut -d'0' -f1) + +expected_start_text_addr=$(grep " a text_start$" .tmp_symbols.txt | cut -d' ' -f1 | sed "s/^0/$top_vma/") + +start_text_addr=$(grep " t start_text$" .tmp_symbols.txt | cut -d' ' -f1) + +if [ "$start_text_addr" != "$expected_start_text_addr" ]; then + echo "ERROR: start_text address is $start_text_addr, should be $expected_start_text_addr" 1>&2 + echo "ERROR: try to enable LD_HEAD_STUB_CATCH config option" 1>&2 + echo "ERROR: see comments in arch/powerpc/tools/head_check.sh" 1>&2 + + exit 1 +fi + +rm -f .tmp_symbols.txt |