1 # Copyright © 2016 IBM Corporation 2 3 # This program is free software; you can redistribute it and/or 4 # modify it under the terms of the GNU General Public License 5 # as published by the Free Software Foundation; either version 6 # 2 of the License, or (at your option) any later version. 7 8 # This script checks the head of a vmlinux for linker stubs that 9 # break our placement of fixed-location code for 64-bit. 10 11 # based on relocs_check.pl 12 # Copyright © 2009 IBM Corporation 13 14 # NOTE! 15 # 16 # If the build dies here, it's likely code in head_64.S/exception-64*.S or 17 # nearby, is branching to labels it can't reach directly, which results in the 18 # linker inserting branch stubs. This can move code around in ways that break 19 # the fixed section calculations (head-64.h). To debug this, disassemble the 20 # vmlinux and look for branch stubs (long_branch, plt_branch, etc.) in the 21 # fixed section region (0 - 0x8000ish). Check what code is calling those stubs, 22 # and perhaps change so a direct branch can reach. 23 # 24 # A ".linker_stub_catch" section is used to catch some stubs generated by 25 # early .text code, which tend to get placed at the start of the section. 26 # If there are too many such stubs, they can overflow this section. Expanding 27 # it may help (or reducing the number of stub branches). 28 # 29 # Linker stubs use the TOC pointer, so even if fixed section code could 30 # tolerate them being inserted into head code, they can't be allowed in low 31 # level entry code (boot, interrupt vectors, etc) until r2 is set up. This 32 # could cause the kernel to die in early boot. 33 34 # Allow for verbose output 35 if [ "$V" = "1" ]; then 36 set -x 37 fi 38 39 if [ $# -lt 2 ]; then 40 echo "$0 [path to nm] [path to vmlinux]" 1>&2 41 exit 1 42 fi 43 44 # Have Kbuild supply the path to nm so we handle cross compilation. 45 nm="$1" 46 vmlinux="$2" 47 48 # gcc-4.6-era toolchain make _stext an A (absolute) symbol rather than T 49 $nm "$vmlinux" | grep -e " [TA] _stext$" -e " t start_first_256B$" -e " a text_start$" -e " t start_text$" > .tmp_symbols.txt 50 51 52 vma=$(grep -e " [TA] _stext$" .tmp_symbols.txt | cut -d' ' -f1) 53 54 expected_start_head_addr="$vma" 55 56 start_head_addr=$(grep " t start_first_256B$" .tmp_symbols.txt | cut -d' ' -f1) 57 58 if [ "$start_head_addr" != "$expected_start_head_addr" ]; then 59 echo "ERROR: head code starts at $start_head_addr, should be $expected_start_head_addr" 1>&2 60 echo "ERROR: try to enable LD_HEAD_STUB_CATCH config option" 1>&2 61 echo "ERROR: see comments in arch/powerpc/tools/head_check.sh" 1>&2 62 63 exit 1 64 fi 65 66 top_vma=$(echo "$vma" | cut -d'0' -f1) 67 68 expected_start_text_addr=$(grep " a text_start$" .tmp_symbols.txt | cut -d' ' -f1 | sed "s/^0/$top_vma/") 69 70 start_text_addr=$(grep " t start_text$" .tmp_symbols.txt | cut -d' ' -f1) 71 72 if [ "$start_text_addr" != "$expected_start_text_addr" ]; then 73 echo "ERROR: start_text address is $start_text_addr, should be $expected_start_text_addr" 1>&2 74 echo "ERROR: try to enable LD_HEAD_STUB_CATCH config option" 1>&2 75 echo "ERROR: see comments in arch/powerpc/tools/head_check.sh" 1>&2 76 77 exit 1 78 fi 79 80 rm -f .tmp_symbols.txt
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.