Messages in this thread | | | Date | Sat, 22 Apr 2006 09:06:10 +0200 | From | Heiko Carstens <> | Subject | Re: [uml-devel] Re: [RFC] PATCH 3/4 - Time virtualization : PTRACE_SYSCALL_MASK |
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> For UML, instead, it's important to set that some peculiar syscalls are not > traced, that the mask is 1-extended and that errors are reported. > > So, I suggest a "flags" parameter for this. Sadly, we're using the ptrace() > syscall and there's no 5th argument normally, we could either use it (IIRC > some calls use the 5th regs indeed), or pass as "data" a struct with flags > and the mask. > > 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). > > probably with a reasonable prefix to avoid namespace pollution (something like > "PT_SC_-").
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.
> > The tracing process won't see > > any of the non existant syscalls it requested to see anyway. > No, you misunderstood the code, it does the opposite very different - the loop
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