On Mon, Jan 16, 2012 at 12:37 PM, Oleg Nesterov <oleg@xxxxxxxxxx> wrote: > On 01/13, Will Drewry wrote: >> >> On Fri, Jan 13, 2012 at 1:01 PM, Will Drewry <wad@xxxxxxxxxxxx> wrote: >> > On Fri, Jan 13, 2012 at 11:31 AM, Oleg Nesterov <oleg@xxxxxxxxxx> wrote: >> >> >> >> Me too. I see no point in using user_regs_struct. >> > >> > I'll rev the change to use pt_regs and drop all the helper code. If >> > no one says otherwise, that certainly seems ideal from a performance >> > perspective, and I see pt_regs exported to userland along with ptrace >> > abi register offset macros. >> >> On second thought, pt_regs is scary :) >> >> From looking at >> http://lxr.linux.no/linux+v3.2.1/arch/x86/include/asm/syscall.h#L97 >> and ia32syscall enty code, it appears that for x86, at least, the >> pt_regs for compat processes will be 8 bytes wide per register on the >> stack. This means if a self-filtering 32-bit program runs on a 64-bit host in >> IA32_EMU, its filters will always index into pt_regs incorrectly. > > Yes, thanks, I forgot about compat tasks again. But this is easy, just > we need regs_64_to_32(). Yup - we could make the assumption that is_compat_task is always 32-bit and the pt_regs is always 64-bit, then copy_and_truncate with regs_64_to_32. Seems kinda wonky though :/ > Doesn't matter. I think Indan has a better suggestion. I disagree, but perhaps I'm not fully understanding! Thanks! will -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
