On 06/09/2015 09:11 PM, Andy Lutomirski wrote: > On Tue, Jun 9, 2015 at 12:03 PM, Denys Vlasenko <dvlas...@redhat.com> wrote: >> On 06/09/2015 09:01 PM, Andy Lutomirski wrote: >>> On Tue, Jun 9, 2015 at 11:54 AM, Denys Vlasenko <dvlas...@redhat.com> wrote: >>>> This doesn't change much, but this uses shorter 32-bit insns: >>>> >>>> -48 8b 74 24 68 mov 0x68(%rsp),%rsi >>>> -48 8b 7c 24 70 mov 0x70(%rsp),%rdi >>>> -48 8b 54 24 60 mov 0x60(%rsp),%rdx >>>> +8b 74 24 68 mov 0x68(%rsp),%esi >>>> +8b 7c 24 70 mov 0x70(%rsp),%edi >>>> +8b 54 24 60 mov 0x60(%rsp),%edx >>>> >>>> Since these are the only uses of RESTORE_RSI_RDI[_RDX], drop these macros. >>>> >>> >>> It probably doesn't matter for these fast paths, but, for the full >>> slow path return, we really do need to restore the full pt_regs. >>> After all, the syscall we're returning from might be sigreturn. >> >> This is compat 32-bit syscall handling code. >> IIUC we do not restore high half of any registers for 32-bit tasks. >> >> Am I missing something? > > Yes -- 64-bit tasks can call 32-bit compat syscalls.
Not via SYSCALL and SYSENTER code paths. This patch touches only those code paths. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
