Messages in this thread | | | Date | Tue, 25 Apr 2006 11:59:42 -0400 | From | Jeff Dike <> | Subject | Re: [uml-devel] Re: [RFC] PATCH 3/4 - Time virtualization : PTRACE_SYSCALL_MASK |
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On Sat, Apr 22, 2006 at 09:06:10AM +0200, Heiko Carstens wrote: > > The flags could be: > > > > MASK_DEFAULT_TRACE (set the default to 1 for remaining bits) > > MASK_DEFAULT_IGNORE (set the default to 0 for remaining bits) > > MASK_STRICT_VERIFY (return -EINVAL for bits exceeding NR_syscalls and set > > differently than the default).
I'd prefer (given that there aren't any unused ptrace arguments) using the operation for this - PTRACE_SYSCALL_MASK_TRACE, PTRACE_SYSCALL_MASK_IGNORE. We'd need better names than these horribly over-long ones, though.
> You might as well introduce yet another ptrace call which returns the number > of system calls and for this ptrace call force user space to pass a complete > bitmap. Sounds easier to me.
I think that's just building in fragility whenever userspace doesn't happen to match the kernel. Both UML and strace will know what system calls they are interested in. Having the kernel 1- or 0-extend the mask will automatically do the right thing. If userspace is newer than the kernel, and asks for special treatment for system calls that don't exist, then it should get a -EINVAL.
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