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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Apr 28, 2020 at 12:15:46PM +0100, Vincenzo Frascino wrote: > On 4/28/20 12:11 PM, Mark Rutland wrote: > > On Tue, Apr 28, 2020 at 11:54:25AM +0100, Vincenzo Frascino wrote: > >> On 4/28/20 8:34 AM, Will Deacon wrote: > >>> On Wed, Apr 15, 2020 at 10:23:36AM +0100, Szabolcs Nagy wrote: > >>>> On aarch64 linux gcc uses -fasynchronous-unwind-tables -funwind-tables > >>>> by default since gcc-8, so now the de facto platform ABI is to allow > >>>> unwinding from async signal handlers. > >>>> > >>>> However on bare metal targets (aarch64-none-elf), and on old gcc, > >>>> async and sync unwind tables are not enabled by default to avoid > >>>> runtime memory costs. > >>>> > >>>> This means if linux is built with a baremetal toolchain the vdso.so > >>>> may not have unwind tables which breaks our (undocumented) platform > >>>> ABI guarantee in userspace. So adding -fasynchronous-unwind-tables > >>>> explicitly to the vgettimeofday.o cflags would be nice (the other > >>>> objects in the vdso seem to be asm). > >>>> > >>>> There was also a report that android clang built linux vdso.so lacks > >>>> .eh_frame completely, that may be a missing --eh-frame-hdr or different > >>>> platform ABI on android, Tamas on cc may be able to verify this. > >>> > >>> Vincenzo? Looks like this is a regression caused by the move to C -- please > >>> can you take a look? > >> > >> I have already, locally, a patch that addresses the problem presented in this > >> email, based on Szabolcs comment. I did not post it yet because I was waiting > >> for Tamas' comment and address everything in one go. > > > > Can I suggest that you post the patch as-is here, even if it's not > > complete, so that we can all review/test in parallel? > > > > Sure, I will write a sensible comment and send it out. Thanks! Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel