From efdb4167e676aaba7505bec739785b76e206cb45 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Tue, 25 Oct 2016 09:51:11 -0500 Subject: [PATCH] scripts/faddr2line: Fix "size mismatch" error I'm not sure how we missed this problem before. When I take a function address and size from an oops and give it to faddr2line, it usually complains about a size mismatch: $ scripts/faddr2line ~/k/vmlinux write_sysrq_trigger+0x51/0x60 skipping write_sysrq_trigger address at 0xffffffff815731a1 due to size mismatch (0x60 != 83) no match for write_sysrq_trigger+0x51/0x60 The problem is caused by differences in how kallsyms and faddr2line determine a function's size. kallsyms calculates a function's size by parsing the output of 'nm -n' and subtracting the next function's address from the current function's address. This means that nop instructions after the end of the function are included in the size. In contrast, faddr2line reads the size from the symbol table, which does *not* include the ending nops in the function's size. Change faddr2line to calculate the size from the output of 'nm -n' to be consistent with kallsyms and oops outputs. Signed-off-by: Josh Poimboeuf Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/bd313ed7c4003f6b1fda63e825325c44a9d837de.1477405374.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- scripts/faddr2line | 33 +++++++++++++++++++++------------ 1 file changed, 21 insertions(+), 12 deletions(-) diff --git a/scripts/faddr2line b/scripts/faddr2line index 450b33257339..29df825d375c 100755 --- a/scripts/faddr2line +++ b/scripts/faddr2line @@ -105,9 +105,18 @@ __faddr2line() { # In rare cases there might be duplicates. while read symbol; do local fields=($symbol) - local sym_base=0x${fields[1]} - local sym_size=${fields[2]} - local sym_type=${fields[3]} + local sym_base=0x${fields[0]} + local sym_type=${fields[1]} + local sym_end=0x${fields[3]} + + # calculate the size + local sym_size=$(($sym_end - $sym_base)) + if [[ -z $sym_size ]] || [[ $sym_size -le 0 ]]; then + warn "bad symbol size: base: $sym_base end: $sym_end" + DONE=1 + return + fi + sym_size=0x$(printf %x $sym_size) # calculate the address local addr=$(($sym_base + $offset)) @@ -116,26 +125,26 @@ __faddr2line() { DONE=1 return fi - local hexaddr=0x$(printf %x $addr) + addr=0x$(printf %x $addr) # weed out non-function symbols - if [[ $sym_type != "FUNC" ]]; then + if [[ $sym_type != t ]] && [[ $sym_type != T ]]; then [[ $print_warnings = 1 ]] && - echo "skipping $func address at $hexaddr due to non-function symbol" + echo "skipping $func address at $addr due to non-function symbol of type '$sym_type'" continue fi # if the user provided a size, make sure it matches the symbol's size if [[ -n $size ]] && [[ $size -ne $sym_size ]]; then [[ $print_warnings = 1 ]] && - echo "skipping $func address at $hexaddr due to size mismatch ($size != $sym_size)" + echo "skipping $func address at $addr due to size mismatch ($size != $sym_size)" continue; fi # make sure the provided offset is within the symbol's range if [[ $offset -gt $sym_size ]]; then [[ $print_warnings = 1 ]] && - echo "skipping $func address at $hexaddr due to size mismatch ($offset > $sym_size)" + echo "skipping $func address at $addr due to size mismatch ($offset > $sym_size)" continue fi @@ -143,12 +152,12 @@ __faddr2line() { [[ $FIRST = 0 ]] && echo FIRST=0 - local hexsize=0x$(printf %x $sym_size) - echo "$func+$offset/$hexsize:" - addr2line -fpie $objfile $hexaddr | sed "s; $dir_prefix\(\./\)*; ;" + # pass real address to addr2line + echo "$func+$offset/$sym_size:" + addr2line -fpie $objfile $addr | sed "s; $dir_prefix\(\./\)*; ;" DONE=1 - done < <(readelf -sW $objfile | awk -v f=$func '$8 == f {print}') + done < <(nm -n $objfile | awk -v fn=$func '$3 == fn { found=1; line=$0; start=$1; next } found == 1 { found=0; print line, $1 }') } [[ $# -lt 2 ]] && usage