Again, I think the patch is fine, just a question On 06/20, Andy Lutomirski wrote: > > System call restart has some oddities wrt ptrace: > > 1. For whatever reason, the kernel delivers signals and triggers > ptrace before handling syscall restart. This means that > -ERESTART_RESTARTBLOCK, etc is visible to userspace. We could > plausibly get away with changing that, but it seems quite risky.
How we can change this? The kernel simply can't know how it should react to (say) -ERESTARTSYS until debugger acks/nacks/changes the signal reported by tracee. > + /* > + * A 32-bit ptracer has the following expectations: > + * > + * - Storing -1 (i.e. 0xffffffff) to orig_eax will prevent > + * syscall restart handling. > + * > + * - Restoring regs saved on exit from an interrupted > + * restartable syscall will trigger syscall restart. Such > + * regs will have non-negative orig_eax and negative eax. > + * > + * The kernel's syscall restart code treats regs->orig_ax and > + * regs->ax as 64-bit signed quantities. 32-bit user code > + * doesn't care about the high bits. Keep it simple and just > + * sign-extend both values. > + */ > + R32_SIGNED(orig_eax, orig_ax); > + R32_SIGNED(eax, ax); OK. but do we really need R32_SIGNED(orig_eax) ? syscall_get_nr() returns "int", not "long". Oleg.
