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Message-ID: <98faa8f0-4b84-0d34-f3e8-06aee6bb7511@quicinc.com>
Date: Fri, 7 Apr 2023 13:08:34 -0700
From: John Moon <quic_johmoo@...cinc.com>
To: Masahiro Yamada <masahiroy@...nel.org>
CC: Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Nicolas Schier <nicolas@...sle.eu>,
<linux-kbuild@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-arm-msm@...r.kernel.org>,
"Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
Randy Dunlap <rdunlap@...radead.org>,
Arnd Bergmann <arnd@...db.de>,
Bjorn Andersson <andersson@...nel.org>,
Todd Kjos <tkjos@...gle.com>,
Matthias Maennich <maennich@...gle.com>,
Giuliano Procida <gprocida@...gle.com>,
<kernel-team@...roid.com>, <libabigail@...rceware.org>,
Jordan Crouse <jorcrous@...zon.com>,
Trilok Soni <quic_tsoni@...cinc.com>,
"Satya Durga Srinivasu Prabhala" <quic_satyap@...cinc.com>,
Elliot Berman <quic_eberman@...cinc.com>,
Guru Das Srinagesh <quic_gurus@...cinc.com>
Subject: Re: [PATCH v4 1/2] check-uapi: Introduce check-uapi.sh
On 4/7/2023 12:19 PM, Masahiro Yamada wrote:
> On Tue, Mar 28, 2023 at 2:42 AM John Moon <quic_johmoo@...cinc.com> wrote:
>>
>> While the kernel community has been good at maintaining backwards
>> compatibility with kernel UAPIs, it would be helpful to have a tool
>> to check if a commit introduces changes that break backwards
>> compatibility.
>>
>> To that end, introduce check-uapi.sh: a simple shell script that
>> checks for changes to UAPI headers using libabigail.
>>
>> libabigail is "a framework which aims at helping developers and
>> software distributors to spot some ABI-related issues like interface
>> incompatibility in ELF shared libraries by performing a static
>> analysis of the ELF binaries at hand."
>>
>> The script uses one of libabigail's tools, "abidiff", to compile the
>> changed header before and after the commit to detect any changes.
>>
>> abidiff "compares the ABI of two shared libraries in ELF format. It
>> emits a meaningful report describing the differences between the two
>> ABIs."
>>
>> The script also includes the ability to check the compatibility of
>> all UAPI headers across commits. This allows developers to inspect
>> the stability of the UAPIs over time.
>>
>> Signed-off-by: John Moon <quic_johmoo@...cinc.com>
>> ---
>> - Refactored to exclusively check headers installed by make
>> headers_install. This simplified the code dramatically and removed
>> the need to perform complex git diffs.
>> - Removed the "-m" flag. Since we're checking all installed headers
>> every time, a flag to check only modified files didn't make sense.
>> - Added info message when usr/include/Makefile is not present that
>> it's likely because that file was only introduced in v5.3.
>> - Changed default behavior of log file. Now, the script will not
>> create a log file unless you pass "-l <file>".
>> - Simplified exit handler.
>> - Added -j $MAX_THREADS to make headers_install to improve speed.
>> - Cleaned up variable references.
>>
>> scripts/check-uapi.sh | 488 ++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 488 insertions(+)
>> create mode 100755 scripts/check-uapi.sh
>>
>
>> +
>> +# Save the current git tree state, stashing if needed
>> +save_tree_state() {
>> + printf "Saving current tree state... "
>> + current_ref="$(git rev-parse HEAD)"
>> + readonly current_ref
>> + if tree_is_dirty; then
>> + unstash="true"
>> + git stash push --quiet
>> + fi
>> + printf "OK\n"
>> +}
>> +
>> +# Restore the git tree state, unstashing if needed
>> +restore_tree_state() {
>> + if [ -z "$current_ref" ]; then
>> + return 0
>> + fi
>> +
>> + printf "Restoring current tree state... "
>> + git checkout --quiet "$current_ref"
>
>
> This does not restore the original state.
>
> I was on a branch before running this script.
> After everything is finished, I am on a detached commit
> because $current_ref is not a branch.
>
>
Good point. I think doing this should address:
current_ref="$(git symbolic-ref --short HEAD 2> /dev/null || git rev
parse HEAD)"
Will fix in v5.
>
>
>> + if ! do_compile "$(get_header_tree "$past_ref")/include" "$past_header" "${past_header}.bin" 2> "$log"; then
>> + eprintf "error - couldn't compile version of UAPI header %s at %s\n" "$file" "$past_ref"
>> + cat "$log" >&2
>> + exit "$FAIL_COMPILE"
>> + fi
>> +
>> + "$ABIDIFF" --non-reachable-types "${past_header}.bin" "${base_header}.bin" > "$log" && ret="$?" || ret="$?"
>
>
> [bikeshed] I might want to write like this:
>
> ret=0
> "$ABIDIFF" --non-reachable-types "${past_header}.bin"
> "${base_header}.bin" > "$log" || ret="$?"
>
>
>
Sure, will do.
>
>
>
>
>> +
>> +
>> + if [ "$quiet" = "true" ]; then
>> + run "$base_ref" "$past_ref" "$abi_error_log" "$@" > /dev/null
>> + else
>> + run "$base_ref" "$past_ref" "$abi_error_log" "$@"
>> + fi
>
>
>
> if [ "$quiet" = "true" ]; then
> exec > /dev/null
> fi
>
> run "$base_ref" "$past_ref" "$abi_error_log" "$@"
>
>
>
> is more elegant because this is the last line of main()
> and exit_handler() does not print anything.
>
>
>
Agreed, will do.
>
>
>
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