On Wed, Sep 14, 2016 at 2:29 PM, Dave Hansen <[email protected]> wrote: > On 09/14/2016 02:01 PM, Kyle Huey wrote: >> Signed-off-by: Kyle Huey <[email protected]> >> --- >> arch/x86/entry/syscalls/syscall_32.tbl | 1 + >> arch/x86/kernel/process.c | 80 >> ++++++++++++++++++++++++++++++++++ >> arch/x86/kernel/process_64.c | 66 ---------------------------- >> 3 files changed, 81 insertions(+), 66 deletions(-) > > Could you explain a bit about what is going on here? Is it just a plain > old code move, _why_ you had to do it this way, etc...?
Sure. In the subsequent patches in this series I add an arch_prctl that is available for both 64 and 32 bit programs/kernels. Since process_64.c is only built for 64 bit kernels, this syscall can't stay there anymore. It's not quite a plain move. To leave the existing arch_prctls only accessible to 64 bit callers, I added the is_32 bit and the four early returns for each existing ARCH_BLAH. These cases are now conditionally compiled out in a 32 bit kernel, so we only have to handle the 32 bit process on a 64 bit kernel case at runtime. I considered doing this instead with a compat wrapper for the syscall on 32 bit systems that would filter these arch_prctls before getting to do_arch_prctl. I didn't see any prior art for it, so decided not to proceed that way. - Kyle
