Author: trasz Date: Sat Nov 7 13:09:51 2020 New Revision: 367445 URL: https://svnweb.freebsd.org/changeset/base/367445
Log: Move TDB_USERWR check under 'if (traced)'. If we hadn't been traced in the first place when syscallenter() started executing, we can ignore TDB_USERWR. TDB_USERWR can get set, sure, but if it does, it's because the debugger raced with the syscall, and it cannot depend on winning that race. Reviewed by: kib MFC after: 2 weeks Sponsored by: EPSRC Differential Revision: https://reviews.freebsd.org/D26585 Modified: head/sys/kern/subr_syscall.c Modified: head/sys/kern/subr_syscall.c ============================================================================== --- head/sys/kern/subr_syscall.c Sat Nov 7 05:10:46 2020 (r367444) +++ head/sys/kern/subr_syscall.c Sat Nov 7 13:09:51 2020 (r367445) @@ -97,21 +97,22 @@ syscallenter(struct thread *td) if (p->p_ptevents & PTRACE_SCE) ptracestop((td), SIGTRAP, NULL); PROC_UNLOCK(p); - } - if (__predict_false((td->td_dbgflags & TDB_USERWR) != 0)) { - /* - * Reread syscall number and arguments if debugger - * modified registers or memory. - */ - error = (p->p_sysent->sv_fetch_syscall_args)(td); - se = sa->callp; + + if ((td->td_dbgflags & TDB_USERWR) != 0) { + /* + * Reread syscall number and arguments if debugger + * modified registers or memory. + */ + error = (p->p_sysent->sv_fetch_syscall_args)(td); + se = sa->callp; #ifdef KTRACE - if (KTRPOINT(td, KTR_SYSCALL)) - ktrsyscall(sa->code, se->sy_narg, sa->args); + if (KTRPOINT(td, KTR_SYSCALL)) + ktrsyscall(sa->code, se->sy_narg, sa->args); #endif - if (error != 0) { - td->td_errno = error; - goto retval; + if (error != 0) { + td->td_errno = error; + goto retval; + } } } _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
