[PATCH 5.15 018/120] scripts/faddr2line: Fix regression in name resolution on ppc64le

Greg Kroah-Hartman
2022-12-05T19:38:17Z

From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

[ Upstream commit 2d77de1581bb5b470486edaf17a7d70151131afd ]

Commit 1d1a0e7c5100 ("scripts/faddr2line: Fix overlapping text section
failures") can cause faddr2line to fail on ppc64le on some
distributions, while it works fine on other distributions. The failure
can be attributed to differences in the readelf output.

$ ./scripts/faddr2line vmlinux find_busiest_group+0x00
no match for find_busiest_group+0x00

On ppc64le, readelf adds the localentry tag before the symbol name on
some distributions, and adds the localentry tag after the symbol name on
other distributions. This problem has been discussed previously:

https://lore.kernel.org/bpf/20191211160133.GB4580@calabresa/

This problem can be overcome by filtering out the localentry tags in the
readelf output. Similar fixes are already present in the kernel by way
of the following commits:

1fd6cee127e2 ("libbpf: Fix VERSIONED_SYM_COUNT number parsing")
aa915931ac3e ("libbpf: Fix readelf output parsing for Fedora")

[jpoimboe: rework commit log]

Fixes: 1d1a0e7c5100 ("scripts/faddr2line: Fix overlapping text section failures")
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Link: https://lore.kernel.org/r/20220927075211.897152-1-srikar@linux.vnet.ibm.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
scripts/faddr2line | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/scripts/faddr2line b/scripts/faddr2line
index 57099687e5e1..9e730b805e87 100755
--- a/scripts/faddr2line
+++ b/scripts/faddr2line
@@ -73,7 +73,8 @@ command -v ${ADDR2LINE} >/dev/null 2>&1 || die "${ADDR2LINE} isn't installed"
find_dir_prefix() {
local objfile=$1

- local start_kernel_addr=$(${READELF} --symbols --wide $objfile | ${AWK} '$8 == "start_kernel" {printf "0x%s", $2}')
+ local start_kernel_addr=$(${READELF} --symbols --wide $objfile | sed 's/\[.*\]//' |
+ ${AWK} '$8 == "start_kernel" {printf "0x%s", $2}')
[[ -z $start_kernel_addr ]] && return

local file_line=$(${ADDR2LINE} -e $objfile $start_kernel_addr)
@@ -177,7 +178,7 @@ __faddr2line() {
found=2
break
fi
- done < <(${READELF} --symbols --wide $objfile | ${AWK} -v sec=$sym_sec '$7 == sec' | sort --key=2)
+ done < <(${READELF} --symbols --wide $objfile | sed 's/\[.*\]//' | ${AWK} -v sec=$sym_sec '$7 == sec' | sort --key=2)

if [[ $found = 0 ]]; then
warn "can't find symbol: sym_name: $sym_name sym_sec: $sym_sec sym_addr: $sym_addr sym_elf_size: $sym_elf_size"
@@ -258,7 +259,7 @@ __faddr2line() {

DONE=1

- done < <(${READELF} --symbols --wide $objfile | ${AWK} -v fn=$sym_name '$4 == "FUNC" && $8 == fn')
+ done < <(${READELF} --symbols --wide $objfile | sed 's/\[.*\]//' | ${AWK} -v fn=$sym_name '$4 == "FUNC" && $8 == fn')
}

[[ $# -lt 2 ]] && usage
--
2.35.1