[tip: objtool/core] scripts/faddr2line: Combine three readelf calls into one

[tip-bot2 for Brian Johannesmeyer]

The following commit has been merged into the objtool/core branch of tip:

Commit-ID:     b8d9d9496c1e78a8fd89f4fe9923d12b3c9ad8a3
Gitweb:        https://git.kernel.org/tip/b8d9d9496c1e78a8fd89f4fe9923d12b3c9ad8a3
Author:        Brian Johannesmeyer <bjohannesmeyer@xxxxxxxxx>
AuthorDate:    Mon, 15 Apr 2024 16:55:33 +02:00
Committer:     Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
CommitterDate: Tue, 02 Jul 2024 23:38:36 -07:00

scripts/faddr2line: Combine three readelf calls into one

Rather than calling readelf three separate times to collect three different
types of info, call it only once, and parse out the different types of info
from its output.

Signed-off-by: Brian Johannesmeyer <bjohannesmeyer@xxxxxxxxx>
Link: https://lore.kernel.org/r/20240415145538.1938745-3-bjohannesmeyer@xxxxxxxxx
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
---
 scripts/faddr2line | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/scripts/faddr2line b/scripts/faddr2line
index bf394bf..f011bda 100755
--- a/scripts/faddr2line
+++ b/scripts/faddr2line
@@ -105,10 +105,14 @@ find_dir_prefix() {
 
 run_readelf() {
 	local objfile=$1
-
-	ELF_FILEHEADER=$(${READELF} --file-header $objfile)
-	ELF_SECHEADERS=$(${READELF} --section-headers --wide $objfile)
-	ELF_SYMS=$(${READELF} --symbols --wide $objfile)
+	local out=$(${READELF} --file-header --section-headers --symbols --wide $objfile)
+
+	# This assumes that readelf first prints the file header, then the section headers, then the symbols.
+	# Note: It seems that GNU readelf does not prefix section headers with the "There are X section headers"
+	# line when multiple options are given, so let's also match with the "Section Headers:" line.
+	ELF_FILEHEADER=$(echo "${out}" | sed -n '/There are [0-9]* section headers, starting at offset\|Section Headers:/q;p')
+	ELF_SECHEADERS=$(echo "${out}" | sed -n '/There are [0-9]* section headers, starting at offset\|Section Headers:/,$p' | sed -n '/Symbol table .* contains [0-9]* entries:/q;p')
+	ELF_SYMS=$(echo "${out}" | sed -n '/Symbol table .* contains [0-9]* entries:/,$p')
 }
 
 __faddr2line() {