2023-12-25 18:53:15

by Bjorn Andersson

Subject: [PATCH] scripts/decode_stacktrace.sh: Support LLVM addr2line

The kernel build system adhere to the LLVM environment variable, to
select building the kernel using clang/llvm. In combination with the
ARCH environment variable the kernel can be cross-compiled without the
user specifying the CROSS_COMPILE variable.

The LLVM environment variable is used to specify the suffix of the llvm
executables (such as LLVM=-12 for llvm-addr2line-12), or to omit the
suffix when set to "1" (e.g. llvm-addr2line).

decode_stacktrace.sh allows invoking a specific addr2line executable by
prefixing the command with CROSS_COMPILE. At best allows the user to
trick decode_stacktrace.sh into invoking llvm-addr2line, and it does not
support specifying an alternative version based on the suffix.

Teach decode_stacktrace.sh about the two cases of the LLVM environment
variable, and use this to determine which addr2line to use. The current
behavior is maintained when the LLVM variable is not set.

Signed-off-by: Bjorn Andersson <[email protected]>
---
scripts/decode_stacktrace.sh | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/scripts/decode_stacktrace.sh b/scripts/decode_stacktrace.sh
index 564c5632e1a2..adf1d64477a1 100755
--- a/scripts/decode_stacktrace.sh
+++ b/scripts/decode_stacktrace.sh
@@ -16,6 +16,13 @@ elif type c++filt >/dev/null 2>&1 ; then
cppfilt_opts=-i
fi

+# Determine which addr2line to use
+case "$LLVM" in
+ "" ) addr2line="${CROSS_COMPILE}addr2line";;
+ "1" ) addr2line="llvm-addr2line";;
+ * ) addr2line="llvm-addr2line${LLVM}";;
+esac
+
if [[ $1 == "-r" ]] ; then
vmlinux=""
basepath="auto"
@@ -169,7 +176,7 @@ parse_symbol() {
if [[ $aarray_support == true && "${cache[$module,$address]+isset}" == "isset" ]]; then
local code=${cache[$module,$address]}
else
- local code=$(${CROSS_COMPILE}addr2line -i -e "$objfile" "$address" 2>/dev/null)
+ local code=$(${addr2line} -i -e "$objfile" "$address" 2>/dev/null)
if [[ $aarray_support == true ]]; then
cache[$module,$address]=$code
fi

---
base-commit: 39676dfe52331dba909c617f213fdb21015c8d10
change-id: 20231225-decode-stacktrace-llvm-f260a1614361

Best regards,
--
Bjorn Andersson <[email protected]>

2023-12-26 16:38:13

by Nathan Chancellor

Subject: Re: [PATCH] scripts/decode_stacktrace.sh: Support LLVM addr2line

On Mon, Dec 25, 2023 at 10:52:57AM -0800, Bjorn Andersson wrote:
> The kernel build system adhere to the LLVM environment variable, to
> select building the kernel using clang/llvm. In combination with the
> ARCH environment variable the kernel can be cross-compiled without the
> user specifying the CROSS_COMPILE variable.
>
> The LLVM environment variable is used to specify the suffix of the llvm
> executables (such as LLVM=-12 for llvm-addr2line-12), or to omit the
> suffix when set to "1" (e.g. llvm-addr2line).
>
> decode_stacktrace.sh allows invoking a specific addr2line executable by
> prefixing the command with CROSS_COMPILE. At best allows the user to
> trick decode_stacktrace.sh into invoking llvm-addr2line, and it does not
> support specifying an alternative version based on the suffix.
>
> Teach decode_stacktrace.sh about the two cases of the LLVM environment
> variable, and use this to determine which addr2line to use. The current
> behavior is maintained when the LLVM variable is not set.
>
> Signed-off-by: Bjorn Andersson <[email protected]>

Hmmm, this is the second patch to decode_stacktrace.sh in the same
number of weeks...

https://lore.kernel.org/[email protected]/

Nick pointed out on that one that Carlos's patch from some time ago was
even better at using all LLVM tools and requested testing/review on that
one.

https://lore.kernel.org/[email protected]/

Furthermore, this patch does not handle the LLVM=<prefix>/bin/ syntax
that we support, which I personally use all the time.

Cheers,
Nathan

> ---
> scripts/decode_stacktrace.sh | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/scripts/decode_stacktrace.sh b/scripts/decode_stacktrace.sh
> index 564c5632e1a2..adf1d64477a1 100755
> --- a/scripts/decode_stacktrace.sh
> +++ b/scripts/decode_stacktrace.sh
> @@ -16,6 +16,13 @@ elif type c++filt >/dev/null 2>&1 ; then
> cppfilt_opts=-i
> fi
>
> +# Determine which addr2line to use
> +case "$LLVM" in
> + "" ) addr2line="${CROSS_COMPILE}addr2line";;
> + "1" ) addr2line="llvm-addr2line";;
> + * ) addr2line="llvm-addr2line${LLVM}";;
> +esac
> +
> if [[ $1 == "-r" ]] ; then
> vmlinux=""
> basepath="auto"
> @@ -169,7 +176,7 @@ parse_symbol() {
> if [[ $aarray_support == true && "${cache[$module,$address]+isset}" == "isset" ]]; then
> local code=${cache[$module,$address]}
> else
> - local code=$(${CROSS_COMPILE}addr2line -i -e "$objfile" "$address" 2>/dev/null)
> + local code=$(${addr2line} -i -e "$objfile" "$address" 2>/dev/null)
> if [[ $aarray_support == true ]]; then
> cache[$module,$address]=$code
> fi
>
> ---
> base-commit: 39676dfe52331dba909c617f213fdb21015c8d10
> change-id: 20231225-decode-stacktrace-llvm-f260a1614361
>
> Best regards,
> --
> Bjorn Andersson <[email protected]>
>
>