Re: [PATCH] Revert "scripts/faddr2line: Combine three readelf calls into one"

[Josh Poimboeuf <jpoimboe@kernel.org>]

On Sat, Sep 05, 2026 at 06:54:49AM +0530, Srikar Dronamraju wrote:
> This reverts commit b8d9d9496c1e ("scripts/faddr2line: Combine three
> readelf calls into one")
> 
> scripts/faddr2line stopped working on PowerPc systems with this commit.
> 
> Output  of scripts/faddr2line on latest kernel sources
> $ scripts/faddr2line ./vmlinux need_active_balance+0x1d4/0x21c
> $
> Output of scripts/faddr2line with revert
> $ scripts/faddr2line ./vmlinux need_active_balance+0x1d4/0x21c
> need_active_balance+0x1d4/0x21c:
> imbalanced_active_balance at kernel/sched/fair.c:12047
> (inlined by) need_active_balance at kernel/sched/fair.c:12061
> $
> 
> readelf on Powerpc when passed with --file-header --section-headers
> --symbol --wide option doesnt show the line
>  "There are 62 section headers, starting at offset 0x16f1a850:"
> 
> Hence faddr2line parsing gets broken.
> 
> It could be a bug in Powerpc readelf that this line doesnt get printed.
> However since its breaking with existing readelf, its better to be
> reverted.
> 
> With the revert, we end up calling readelf three times but this should
> still be fine since calling faddr2line is a debug tool.
> 
> Fixes: b8d9d9496c1e ("scripts/faddr2line: Combine three readelf calls into one")
> Signed-off-by: Srikar Dronamraju <srikar@linux.ibm.com>

Can you run

  bash -x scripts/faddr2line ./vmlinux need_active_balance+0x1d4/0x21c

to see what line it's failing at?

Any chance the below fixes it?

diff --git a/scripts/faddr2line b/scripts/faddr2line
index 622875396bcfc..550c0f9b9d473 100755
--- a/scripts/faddr2line
+++ b/scripts/faddr2line
@@ -78,7 +78,7 @@ GREP="grep"
 
 # Enforce ASCII-only output from tools like readelf
 # ensuring sed processes strings correctly.
-export LANG=C
+export LC_ALL=C
 
 command -v ${AWK} >/dev/null 2>&1 || die "${AWK} isn't installed"
 command -v ${READELF} >/dev/null 2>&1 || die "${READELF} isn't installed"