On Thu, Mar 17, 2022 at 12:20:11PM -0700, Rick Edgecombe wrote: > In ptrace, the x86_32_regsets and x86_64_regsets are constructed such that > there are no gaps in the arrays. This appears to be for two reasons. One, > the code in fill_thread_core_info() can't handle the gaps. This will be > addressed in a future patch. And two, not having gaps shrinks the size of > the array in memory. > > Both regset arrays draw their indices from a shared enum x86_regset, but 32 > bit and 64 bit don't all support the same regsets. In the case of > IA32_EMULATION they can be compiled in at the same time. So this enum has > to be laid out in a special way such that there are no gaps for both > x86_32_regsets and x86_64_regsets. This involves creating aliases for > enum’s that are only in one view or the other, or creating multiple > versions like in the case of REGSET_IOPERM32/REGSET_IOPERM64. > > Simplify the construction of these arrays by just fully separating out the > enums for 32 bit and 64 bit. Add some bitsize-free defines for > REGSET_GENERAL and REGSET_FP since they are the only two referred to in > bitsize generic code. Also, change the name pattern to be like > REGSET32_FOO, instead of REGSET_FOO32, to better emphasize that the bit > size is the bitsize of the architecture, not the register itself. > > This should have no functional change and is only changing how constants > are generated and named. The enum is local to this file, so it does not > introduce any burden on code calling from other places in the kernel now > having to worry about whether to use a 32 bit or 64 bit enum name. > > [1] https://lore.kernel.org/lkml/20180717162502.32274-1-yu-cheng.yu@xxxxxxxxx/ > > Signed-off-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx> > Acked-by: Kees Cook <keescook@xxxxxxxxxxxx> > > --- > > v2: > - Rename REGSET_FOO32 to REGSET32_FOO (Eric Biederman) > - Drop Kees' Reviewed-by to Acked-by, due to changing enum value names I think of "Ack" to mean "I am a maintainer of this area and someone can carry this instead of it going via my tree". While I certainly poke and ptrace and x86 a lot, I probably wouldn't Ack in this part of the kernel. But it does seem "Reviewed-by" is a stronger signal[1]. Regardless, v2 looks good to me still. :) Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> -Kees [1] https://www.kernel.org/doc/html/latest/process/submitting-patches.html#when-to-use-acked-by-cc-and-co-developed-by -- Kees Cook
