Hi Dave, On Mon, 29 Feb 2016 11:49:31 -0800 Dave Hansen <dave@xxxxxxxx> wrote: > > This responds to the feedback from Ingo that we should be using > explicitly-sized types. Beat me to it by seconds :-) > From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> > > Stephen Rothwell reported: > > http://lkml.kernel.org/r/20160226164406.065a1ffc@xxxxxxxxxxxxxxxx > > that the Memory Protection Keys patches from the tip tree broke > a build-time check on an ARM build because they changed the ABI > of siginfo. > > A u64 was used for the protection key field in siginfo. When the > containing union was aligned, this u64 unioned nicely with the > two 'void *'s in _addr_bnd. But, on 32-bit, if the union was > unaligned, the u64 might grow the size of the union, breaking the > ABI for subsequent fields. > > To fix this, we replace the u64 with an 'unsigned long'. The long > is guaranteed to union well with the pointers from _addr_bnd. It > is also plenty large enough to store the 16-bit pkey we have today > on x86. This also has the advantage that it allows existing 64-bit > userspace to keep working without modification. s/(unsigned )?long/__u32/g and the last sentence no longer makes sense. > I also shouldn't have been using a u64 in a userspace API to begin > with. > > Fixes: cd0ea35ff551 ("signals, pkeys: Notify userspace about protection key faults") > Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> > Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Cc: Ingo Molnar <mingo@xxxxxxx> > Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Cc: linux-next@xxxxxxxxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx > Cc: Helge Deller <deller@xxxxxx> Acked-by: Stehen Rothwell <sfr@xxxxxxxxxxxxxxxx> -- Cheers, Stephen Rothwell -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
