# git rev-parse -q --verify 24321ac668e452a4942598533d267805f291fdc9^{commit} 24321ac668e452a4942598533d267805f291fdc9 already have revision, skipping fetch # git checkout -q -f -B kisskb 24321ac668e452a4942598533d267805f291fdc9 # git clean -qxdf # < git log -1 # commit 24321ac668e452a4942598533d267805f291fdc9 # Author: Raoni Fassina Firmino # Date: Mon Feb 1 17:05:05 2021 -0300 # # powerpc/64/signal: Fix regression in __kernel_sigtramp_rt64() semantics # # Commit 0138ba5783ae ("powerpc/64/signal: Balance return predictor # stack in signal trampoline") changed __kernel_sigtramp_rt64() VDSO and # trampoline code, and introduced a regression in the way glibc's # backtrace()[1] detects the signal-handler stack frame. Apart from the # practical implications, __kernel_sigtramp_rt64() was a VDSO function # with the semantics that it is a function you can call from userspace # to end a signal handling. Now this semantics are no longer valid. # # I believe the aforementioned change affects all releases since 5.9. # # This patch tries to fix both the semantics and practical aspect of # __kernel_sigtramp_rt64() returning it to the previous code, whilst # keeping the intended behaviour of 0138ba5783ae by adding a new symbol # to serve as the jump target from the kernel to the trampoline. Now the # trampoline has two parts, a new entry point and the old return point. # # [1] https://lists.ozlabs.org/pipermail/linuxppc-dev/2021-January/223194.html # # Fixes: 0138ba5783ae ("powerpc/64/signal: Balance return predictor stack in signal trampoline") # Cc: stable@vger.kernel.org # v5.9+ # Signed-off-by: Raoni Fassina Firmino # Acked-by: Nicholas Piggin # [mpe: Minor tweaks to change log formatting, add stable tag] # Signed-off-by: Michael Ellerman # Link: https://lore.kernel.org/r/20210201200505.iz46ubcizipnkcxe@work-tp # < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-gcc --version # < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld --version # < git log --format=%s --max-count=1 24321ac668e452a4942598533d267805f291fdc9 # < make -s -j 8 ARCH=powerpc O=/kisskb/build/powerpc-fixes_pseries_defconfig+NO_MEMORY_HOTPLUG_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- pseries_defconfig # Added to kconfig CONFIG_MEMORY_HOTPLUG=n # Added to kconfig CONFIG_MEMORY_HOTREMOVE=n # < make -s -j 8 ARCH=powerpc O=/kisskb/build/powerpc-fixes_pseries_defconfig+NO_MEMORY_HOTPLUG_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- help # make -s -j 8 ARCH=powerpc O=/kisskb/build/powerpc-fixes_pseries_defconfig+NO_MEMORY_HOTPLUG_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- olddefconfig # make -s -j 8 ARCH=powerpc O=/kisskb/build/powerpc-fixes_pseries_defconfig+NO_MEMORY_HOTPLUG_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- Completed OK # rm -rf /kisskb/build/powerpc-fixes_pseries_defconfig+NO_MEMORY_HOTPLUG_powerpc-gcc5 # Build took: 0:04:53.681760