Date: Wed, 7 Oct 2015 00:50:26 +0000 (UTC) From: John Baldwin <jhb@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r288969 - in stable: 10/sys/kern 9/sys/kern Message-ID: <201510070050.t970oQxV003127@repo.freebsd.org>
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Author: jhb Date: Wed Oct 7 00:50:26 2015 New Revision: 288969 URL: https://svnweb.freebsd.org/changeset/base/288969 Log: MFC 287870: 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. Modified: stable/10/sys/kern/subr_syscall.c Directory Properties: stable/10/ (props changed) Changes in other areas also in this revision: Modified: stable/9/sys/kern/subr_syscall.c Directory Properties: stable/9/sys/ (props changed) Modified: stable/10/sys/kern/subr_syscall.c ============================================================================== --- stable/10/sys/kern/subr_syscall.c Wed Oct 7 00:43:05 2015 (r288968) +++ stable/10/sys/kern/subr_syscall.c Wed Oct 7 00:50:26 2015 (r288969) @@ -64,14 +64,14 @@ syscallenter(struct thread *td, struct s td->td_pticks = 0; if (td->td_ucred != p->p_ucred) cred_update_thread(td); - if (p->p_flag & P_TRACED) { - traced = 1; + traced = (p->p_flag & P_TRACED) != 0; + if (traced || td->td_dbgflags & TDB_USERWR) { PROC_LOCK(p); td->td_dbgflags &= ~TDB_USERWR; - td->td_dbgflags |= TDB_SCE; + if (traced) + td->td_dbgflags |= TDB_SCE; PROC_UNLOCK(p); - } else - traced = 0; + } error = (p->p_sysent->sv_fetch_syscall_args)(td, sa); #ifdef KTRACE if (KTRPOINT(td, KTR_SYSCALL))
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