Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | Date | Mon, 10 Dec 2018 19:03:33 +0000 | From | Will Deacon <> | Subject | Re: [PATCH 2/2] locking/atomics: Check atomic headers with sha1sum |
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On Mon, Dec 10, 2018 at 05:50:35PM +0000, Mark Rutland wrote: > We currently check the atomic headers at build-time to ensure they > haven't been modified directly, and these checks require regenerating > the headers in full. As this takes a few seconds, even when > parallelized, this is too slow to run for every kernel build. > > Instead, we can generate a hash of each header as we generate them, > which we can cheaply check at build time (~0.16s for all headers). > > This patch does so, updating headers with their hashes using the new > gen-atomics.sh script. As some users apparently build the kernel wihout > coreutils, lacking sha1sum, the checks are skipped in this case. > Presumably, most developers have a working coreutils installation. > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Boqun Feng <boqun.feng@gmail.com> > Cc: Ingo Molnar <mingo@kernel.org> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Will Deacon <will.deacon@arm.com> > --- > include/asm-generic/atomic-instrumented.h | 1 + > include/asm-generic/atomic-long.h | 1 + > include/linux/atomic-fallback.h | 1 + > scripts/atomic/check-atomics.sh | 26 ++++++++++++++++++++------ > scripts/atomic/gen-atomics.sh | 20 ++++++++++++++++++++ > 5 files changed, 43 insertions(+), 6 deletions(-) > create mode 100755 scripts/atomic/gen-atomics.sh > > diff --git a/include/asm-generic/atomic-instrumented.h b/include/asm-generic/atomic-instrumented.h > index b8f5b35216e1..e8730c6b9fe2 100644 > --- a/include/asm-generic/atomic-instrumented.h > +++ b/include/asm-generic/atomic-instrumented.h > @@ -1785,3 +1785,4 @@ atomic64_dec_if_positive(atomic64_t *v) > }) > > #endif /* _ASM_GENERIC_ATOMIC_INSTRUMENTED_H */ > +// b29b625d5de9280f680e42c7be859b55b15e5f6a > diff --git a/include/asm-generic/atomic-long.h b/include/asm-generic/atomic-long.h > index a833d385a70b..881c7e27af28 100644 > --- a/include/asm-generic/atomic-long.h > +++ b/include/asm-generic/atomic-long.h > @@ -1010,3 +1010,4 @@ atomic_long_dec_if_positive(atomic_long_t *v) > > #endif /* CONFIG_64BIT */ > #endif /* _ASM_GENERIC_ATOMIC_LONG_H */ > +// 77558968132ce4f911ad53f6f52ce423006f6268 > diff --git a/include/linux/atomic-fallback.h b/include/linux/atomic-fallback.h > index 1c02c0112fbb..a7d240e465c0 100644 > --- a/include/linux/atomic-fallback.h > +++ b/include/linux/atomic-fallback.h > @@ -2292,3 +2292,4 @@ atomic64_dec_if_positive(atomic64_t *v) > #define atomic64_cond_read_relaxed(v, c) smp_cond_load_relaxed(&(v)->counter, (c)) > > #endif /* _LINUX_ATOMIC_FALLBACK_H */ > +// 25de4a2804d70f57e994fe3b419148658bb5378a > diff --git a/scripts/atomic/check-atomics.sh b/scripts/atomic/check-atomics.sh > index c30101cddf2d..cfa0c2f71c84 100755 > --- a/scripts/atomic/check-atomics.sh > +++ b/scripts/atomic/check-atomics.sh > @@ -7,13 +7,27 @@ ATOMICDIR=$(dirname $0) > ATOMICTBL=${ATOMICDIR}/atomics.tbl > LINUXDIR=${ATOMICDIR}/../.. > > +echo '' | sha1sum - > /dev/null 2>&1 > +if [ $? -ne 0 ]; then > + printf "sha1sum not available, skipping atomic header checks.\n" > + exit 0 > +fi > + > cat <<EOF | > -gen-atomic-instrumented.sh asm-generic/atomic-instrumented.h > -gen-atomic-long.sh asm-generic/atomic-long.h > -gen-atomic-fallback.sh linux/atomic-fallback.h > +asm-generic/atomic-instrumented.h > +asm-generic/atomic-long.h > +linux/atomic-fallback.h > EOF > -while read script header; do > - if ! (${ATOMICDIR}/${script} ${ATOMICTBL} | diff - ${LINUXDIR}/include/${header} > /dev/null); then > - printf "warning: include/${header} is out-of-date.\n" > +while read header; do > + OLDSUM="$(tail -n 1 ${LINUXDIR}/include/${header})" > + OLDSUM="${OLDSUM#// }" > + > + NEWSUM="$(head -n -1 ${LINUXDIR}/include/${header} | sha1sum)" > + NEWSUM="${NEWSUM%% *}"
Here we're relying on head and tail being available, but it looks like they're also part of coreutils, so that should be fine.
> + > + if [ "${OLDSUM}" != "${NEWSUM}" ]; then > + printf "warning: generated include/${header} has been modified.\n" > fi > done > + > +exit 0 > diff --git a/scripts/atomic/gen-atomics.sh b/scripts/atomic/gen-atomics.sh > new file mode 100755 > index 000000000000..27400b0cd732 > --- /dev/null > +++ b/scripts/atomic/gen-atomics.sh > @@ -0,0 +1,20 @@ > +#!/bin/sh > +# SPDX-License-Identifier: GPL-2.0 > +# > +# Generate atomic headers > + > +ATOMICDIR=$(dirname $0) > +ATOMICTBL=${ATOMICDIR}/atomics.tbl > +LINUXDIR=${ATOMICDIR}/../.. > + > +cat <<EOF | > +gen-atomic-instrumented.sh asm-generic/atomic-instrumented.h > +gen-atomic-long.sh asm-generic/atomic-long.h > +gen-atomic-fallback.sh linux/atomic-fallback.h > +EOF > +while read script header; do > + ${ATOMICDIR}/${script} ${ATOMICTBL} > ${LINUXDIR}/include/${header} > + HASH="$(sha1sum ${LINUXDIR}/include/${header})" > + HASH="${HASH%% *}" > + printf "// %s\n" "${HASH}" >> ${LINUXDIR}/include/${header} > +done Thanks, this looks sensible to me:
Acked-by: Will Deacon <will.deacon@arm.com>
Will
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