Messages in this thread | | | From | Denys Vlasenko <> | Subject | Re: Compat 32-bit syscall entry from 64-bit task!? | Date | Thu, 26 Jan 2012 02:21:33 +0100 |
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On Thursday 26 January 2012 01:59, Jamie Lokier wrote: > Denys Vlasenko wrote: > > (2) syscall exit compat-ness is known from entry type - no need to indicate it; and > > (3) if we would flag syscall entry with an event value in wait status, then syscall > > exit will be already distinquisable. > > > > Thus, minimally we need one new option, PTRACE_O_TRACE_SYSENTRY - > > "on syscall entry ptrace stop, set a nonzero event value in wait status" > > , and two event values: PTRACE_EVENT_SYSCALL_ENTRY (for native entry), > > PTRACE_EVENT_SYSCALL_ENTRY1 for compat one. > > PTRACE_EVENT_SYSCALL_EXIT would cleanly indicate that the new option > is actually working without the tracer needing to do a fork+test, if > PTRACE_ATTACH is used and for some reason the tracer sees a syscall > exit first.
Can't happen. After PTRACE_ATTACH, you can only see tracee dying, or getting a signal delivery (usually a SIGSTOP). Anything else would be a kernel bug.
-- vda
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