Always clear TDB_USERWR before fetching system call arguments. The
TDB_USERWR flag may still be set after a debugger detaches from a process via PT_DETACH. Previously the flag would never be cleared forcing a double fetch of the system call arguments for each system call. Note that the flag cannot be cleared at PT_DETACH time in case one of the threads in the process is currently stopped in syscallenter() and the debugger has modified the arguments for that pending system call before detaching. Reviewed by: kib MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D3678
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=287870
@ -63,14 +63,14 @@ syscallenter(struct thread *td, struct syscall_args *sa)
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td->td_pticks = 0;
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if (td->td_cowgen != p->p_cowgen)
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thread_cow_update(td);
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if (p->p_flag & P_TRACED) {
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traced = 1;
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traced = (p->p_flag & P_TRACED) != 0;
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if (traced || td->td_dbgflags & TDB_USERWR) {
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PROC_LOCK(p);
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td->td_dbgflags &= ~TDB_USERWR;
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td->td_dbgflags |= TDB_SCE;
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if (traced)
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td->td_dbgflags |= TDB_SCE;
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PROC_UNLOCK(p);
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} else
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traced = 0;
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}
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error = (p->p_sysent->sv_fetch_syscall_args)(td, sa);
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_SYSCALL))
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