Messages in this thread | | | Date | Sat, 29 Apr 2006 10:49:07 +0200 | From | Heiko Carstens <> | Subject | Re: [uml-devel] [RFC] PATCH 3/4 - Time virtualization : PTRACE_SYSCALL_MASK |
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> Ok, this gives us a definite proposal, which I finally like: > > * to exclude sys_tee: > > bitmask = 0; > set_bit(__NR_tee, bitmask); > ptrace(PTRACE_SET_NOTRACE, bitmask); > > * to trace only sys_tee: > > bitmask = 0; > set_bit(__NR_tee, bitmask); > ptrace(PTRACE_SET_TRACEONLY, bitmask); > > Semantics: > > in both cases, the mask is first zero-extended to the right (for syscalls not > known to userspace), bits for syscall not known to the kernel are checked and > the call fails if any of them is 1, and in the failure case E2BIG or > EOVERFLOW is returned (I want to avoid EINVAL and ENOSYS to avoid confusion) > and the part of the mask known to the kernel is 0-ed. > > In case of success, for NOTRACE (which was DEFAULT_TRACE) the mask is reversed > before copying in the kernel syscall mask, for TRACEONLY it's copied there > directly.
IMHO this is way too complicated. Introducing a ptrace call that returns the number of syscalls and forcing user space to pass a complete bitmask is much easier. Also the semantics are much easier to understand.
In addition your proposal would already introduce a rather complicated interface to figure out how many syscalls the kernel has. I'm sure this will be (mis)used sooner or later. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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