[PATCH 2/2] scripts/faddr2line: Use LLVM addr2line and readelf if LLVM=1

[Will Deacon]

GNU utilities cannot necessarily parse objects built by LLVM, which can
result in confusing errors when using 'faddr2line':

$ CROSS_COMPILE=aarch64-linux-gnu- ./scripts/faddr2line vmlinux do_one_initcall+0xf4/0x260
aarch64-linux-gnu-addr2line: vmlinux: unknown type [0x13] section `.relr.dyn'
aarch64-linux-gnu-addr2line: DWARF error: invalid or unhandled FORM value: 0x25
do_one_initcall+0xf4/0x260:
aarch64-linux-gnu-addr2line: vmlinux: unknown type [0x13] section `.relr.dyn'
aarch64-linux-gnu-addr2line: DWARF error: invalid or unhandled FORM value: 0x25
$x.73 at main.c:?

Although this can be worked around by setting CROSS_COMPILE to "llvm=-",
it's cleaner to follow the same syntax as the top-level Makefile and
accept LLVM=1 as an indication to use the llvm- tools.

Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: John Stultz <jstultz@xxxxxxxxxx>
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
---
 scripts/faddr2line | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/scripts/faddr2line b/scripts/faddr2line
index 60368a1cdaed..24845267efb2 100755
--- a/scripts/faddr2line
+++ b/scripts/faddr2line
@@ -58,8 +58,14 @@ die() {
 	exit 1
 }
 
-READELF="${CROSS_COMPILE:-}readelf"
-ADDR2LINE="${CROSS_COMPILE:-}addr2line"
+if [ "${LLVM:-}" == "1" ]; then
+	UTIL_PREFIX=llvm-
+else
+	UTIL_PREFIX=${CROSS_COMPILE:-}
+fi
+
+READELF="${UTIL_PREFIX}readelf"
+ADDR2LINE="${UTIL_PREFIX}addr2line"
 AWK="awk"
 GREP="grep"
 
-- 
2.41.0.487.g6d72f3e995-goog