Date: Tue, 6 Oct 2015 19:29:05 +0000 (UTC) From: John Baldwin <jhb@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r288949 - in head: sys/kern sys/sys tests/sys/kern Message-ID: <201510061929.t96JT5jT003668@repo.freebsd.org>
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Author: jhb Date: Tue Oct 6 19:29:05 2015 New Revision: 288949 URL: https://svnweb.freebsd.org/changeset/base/288949 Log: Fix various edge cases related to system call tracing. - Always set td_dbg_sc_* when P_TRACED is set on system call entry even if the debugger is not tracing system call entries. This ensures the fields are valid when reporting other stops that occur at system call boundaries such as for PT_FOLLOW_FORKS or when only tracing system call exits. - Set TDB_SCX when reporting the stop for a new child process in fork_return(). This causes the event to be reported as a system call exit. - Report a system call exit event in fork_return() for new threads in a traced process. - Copy td_dbg_sc_* to new threads instead of zeroing. This ensures that td_dbg_sc_code in particular will report the system call that created the new thread or process when it reports a system call exit event in fork_return(). - Add new ptrace tests to verify that new child processes and threads report system call exit events with a valid pl_syscall_code via PT_LWPINFO. Reviewed by: kib Differential Revision: https://reviews.freebsd.org/D3822 Modified: head/sys/kern/kern_fork.c head/sys/kern/subr_syscall.c head/sys/sys/proc.h head/tests/sys/kern/Makefile head/tests/sys/kern/ptrace_test.c Modified: head/sys/kern/kern_fork.c ============================================================================== --- head/sys/kern/kern_fork.c Tue Oct 6 19:07:10 2015 (r288948) +++ head/sys/kern/kern_fork.c Tue Oct 6 19:29:05 2015 (r288949) @@ -57,6 +57,7 @@ __FBSDID("$FreeBSD$"); #include <sys/proc.h> #include <sys/procdesc.h> #include <sys/pioctl.h> +#include <sys/ptrace.h> #include <sys/racct.h> #include <sys/resourcevar.h> #include <sys/sched.h> @@ -1031,8 +1032,8 @@ fork_return(struct thread *td, struct tr { struct proc *p, *dbg; + p = td->td_proc; if (td->td_dbgflags & TDB_STOPATFORK) { - p = td->td_proc; sx_xlock(&proctree_lock); PROC_LOCK(p); if ((p->p_pptr->p_flag & (P_TRACED | P_FOLLOWFORK)) == @@ -1049,9 +1050,9 @@ fork_return(struct thread *td, struct tr p->p_pid, p->p_oppid); proc_reparent(p, dbg); sx_xunlock(&proctree_lock); - td->td_dbgflags |= TDB_CHILD; + td->td_dbgflags |= TDB_CHILD | TDB_SCX; ptracestop(td, SIGSTOP); - td->td_dbgflags &= ~TDB_CHILD; + td->td_dbgflags &= ~(TDB_CHILD | TDB_SCX); } else { /* * ... otherwise clear the request. @@ -1061,6 +1062,18 @@ fork_return(struct thread *td, struct tr cv_broadcast(&p->p_dbgwait); } PROC_UNLOCK(p); + } else if (p->p_flag & P_TRACED) { + /* + * This is the start of a new thread in a traced + * process. Report a system call exit event. + */ + PROC_LOCK(p); + td->td_dbgflags |= TDB_SCX; + _STOPEVENT(p, S_SCX, td->td_dbg_sc_code); + if ((p->p_stops & S_PT_SCX) != 0) + ptracestop(td, SIGTRAP); + td->td_dbgflags &= ~TDB_SCX; + PROC_UNLOCK(p); } userret(td, frame); Modified: head/sys/kern/subr_syscall.c ============================================================================== --- head/sys/kern/subr_syscall.c Tue Oct 6 19:07:10 2015 (r288948) +++ head/sys/kern/subr_syscall.c Tue Oct 6 19:29:05 2015 (r288949) @@ -83,11 +83,12 @@ syscallenter(struct thread *td, struct s if (error == 0) { STOPEVENT(p, S_SCE, sa->narg); - if (p->p_flag & P_TRACED && p->p_stops & S_PT_SCE) { + if (p->p_flag & P_TRACED) { PROC_LOCK(p); td->td_dbg_sc_code = sa->code; td->td_dbg_sc_narg = sa->narg; - ptracestop((td), SIGTRAP); + if (p->p_stops & S_PT_SCE) + ptracestop((td), SIGTRAP); PROC_UNLOCK(p); } if (td->td_dbgflags & TDB_USERWR) { Modified: head/sys/sys/proc.h ============================================================================== --- head/sys/sys/proc.h Tue Oct 6 19:07:10 2015 (r288948) +++ head/sys/sys/proc.h Tue Oct 6 19:29:05 2015 (r288949) @@ -283,8 +283,6 @@ struct thread { int td_no_sleeping; /* (k) Sleeping disabled count. */ int td_dom_rr_idx; /* (k) RR Numa domain selection. */ void *td_su; /* (k) FFS SU private */ - u_int td_dbg_sc_code; /* (c) Syscall code to debugger. */ - u_int td_dbg_sc_narg; /* (c) Syscall arg count to debugger.*/ #define td_endzero td_sigmask /* Copied during fork1() or create_thread(). */ @@ -296,6 +294,8 @@ struct thread { u_char td_pri_class; /* (t) Scheduling class. */ u_char td_user_pri; /* (t) User pri from estcpu and nice. */ u_char td_base_user_pri; /* (t) Base user pri */ + u_int td_dbg_sc_code; /* (c) Syscall code to debugger. */ + u_int td_dbg_sc_narg; /* (c) Syscall arg count to debugger.*/ #define td_endcopy td_pcb /* Modified: head/tests/sys/kern/Makefile ============================================================================== --- head/tests/sys/kern/Makefile Tue Oct 6 19:07:10 2015 (r288948) +++ head/tests/sys/kern/Makefile Tue Oct 6 19:29:05 2015 (r288949) @@ -7,6 +7,7 @@ ATF_TESTS_C+= ptrace_test ATF_TESTS_C+= unix_seqpacket_test TEST_METADATA.unix_seqpacket_test+= timeout="15" +LDADD.ptrace_test+= -lpthread LDADD.unix_seqpacket_test+= -lpthread WARNS?= 5 Modified: head/tests/sys/kern/ptrace_test.c ============================================================================== --- head/tests/sys/kern/ptrace_test.c Tue Oct 6 19:07:10 2015 (r288948) +++ head/tests/sys/kern/ptrace_test.c Tue Oct 6 19:29:05 2015 (r288949) @@ -29,10 +29,12 @@ __FBSDID("$FreeBSD$"); #include <sys/types.h> #include <sys/ptrace.h> +#include <sys/syscall.h> #include <sys/sysctl.h> #include <sys/user.h> #include <sys/wait.h> #include <errno.h> +#include <pthread.h> #include <signal.h> #include <stdio.h> #include <stdlib.h> @@ -409,12 +411,15 @@ ATF_TC_BODY(ptrace__parent_sees_exit_aft * debugger is attached to it. */ static __dead2 void -follow_fork_parent(void) +follow_fork_parent(bool use_vfork) { pid_t fpid, wpid; int status; - CHILD_REQUIRE((fpid = fork()) != -1); + if (use_vfork) + CHILD_REQUIRE((fpid = vfork()) != -1); + else + CHILD_REQUIRE((fpid = fork()) != -1); if (fpid == 0) /* Child */ @@ -434,7 +439,7 @@ follow_fork_parent(void) * child process. */ static pid_t -handle_fork_events(pid_t parent) +handle_fork_events(pid_t parent, struct ptrace_lwpinfo *ppl) { struct ptrace_lwpinfo pl; bool fork_reported[2]; @@ -469,6 +474,8 @@ handle_fork_events(pid_t parent) child = wpid; else ATF_REQUIRE(child == wpid); + if (ppl != NULL) + ppl[1] = pl; fork_reported[1] = true; } else { ATF_REQUIRE(wpid == parent); @@ -478,6 +485,8 @@ handle_fork_events(pid_t parent) child = pl.pl_child_pid; else ATF_REQUIRE(child == pl.pl_child_pid); + if (ppl != NULL) + ppl[0] = pl; fork_reported[0] = true; } } @@ -499,7 +508,7 @@ ATF_TC_BODY(ptrace__follow_fork_both_att ATF_REQUIRE((fpid = fork()) != -1); if (fpid == 0) { trace_me(); - follow_fork_parent(); + follow_fork_parent(false); } /* Parent process. */ @@ -516,7 +525,7 @@ ATF_TC_BODY(ptrace__follow_fork_both_att /* Continue the child ignoring the SIGSTOP. */ ATF_REQUIRE(ptrace(PT_CONTINUE, children[0], (caddr_t)1, 0) != -1); - children[1] = handle_fork_events(children[0]); + children[1] = handle_fork_events(children[0], NULL); ATF_REQUIRE(children[1] > 0); ATF_REQUIRE(ptrace(PT_CONTINUE, children[0], (caddr_t)1, 0) != -1); @@ -555,7 +564,7 @@ ATF_TC_BODY(ptrace__follow_fork_child_de ATF_REQUIRE((fpid = fork()) != -1); if (fpid == 0) { trace_me(); - follow_fork_parent(); + follow_fork_parent(false); } /* Parent process. */ @@ -572,7 +581,7 @@ ATF_TC_BODY(ptrace__follow_fork_child_de /* Continue the child ignoring the SIGSTOP. */ ATF_REQUIRE(ptrace(PT_CONTINUE, children[0], (caddr_t)1, 0) != -1); - children[1] = handle_fork_events(children[0]); + children[1] = handle_fork_events(children[0], NULL); ATF_REQUIRE(children[1] > 0); ATF_REQUIRE(ptrace(PT_CONTINUE, children[0], (caddr_t)1, 0) != -1); @@ -606,7 +615,7 @@ ATF_TC_BODY(ptrace__follow_fork_parent_d ATF_REQUIRE((fpid = fork()) != -1); if (fpid == 0) { trace_me(); - follow_fork_parent(); + follow_fork_parent(false); } /* Parent process. */ @@ -623,7 +632,7 @@ ATF_TC_BODY(ptrace__follow_fork_parent_d /* Continue the child ignoring the SIGSTOP. */ ATF_REQUIRE(ptrace(PT_CONTINUE, children[0], (caddr_t)1, 0) != -1); - children[1] = handle_fork_events(children[0]); + children[1] = handle_fork_events(children[0], NULL); ATF_REQUIRE(children[1] > 0); ATF_REQUIRE(ptrace(PT_DETACH, children[0], (caddr_t)1, 0) != -1); @@ -688,7 +697,7 @@ ATF_TC_BODY(ptrace__follow_fork_both_att ATF_REQUIRE((fpid = fork()) != -1); if (fpid == 0) { attach_fork_parent(cpipe); - follow_fork_parent(); + follow_fork_parent(false); } /* Parent process. */ @@ -715,7 +724,7 @@ ATF_TC_BODY(ptrace__follow_fork_both_att /* Signal the fork parent to continue. */ close(cpipe[0]); - children[1] = handle_fork_events(children[0]); + children[1] = handle_fork_events(children[0], NULL); ATF_REQUIRE(children[1] > 0); ATF_REQUIRE(ptrace(PT_CONTINUE, children[0], (caddr_t)1, 0) != -1); @@ -756,7 +765,7 @@ ATF_TC_BODY(ptrace__follow_fork_child_de ATF_REQUIRE((fpid = fork()) != -1); if (fpid == 0) { attach_fork_parent(cpipe); - follow_fork_parent(); + follow_fork_parent(false); } /* Parent process. */ @@ -783,7 +792,7 @@ ATF_TC_BODY(ptrace__follow_fork_child_de /* Signal the fork parent to continue. */ close(cpipe[0]); - children[1] = handle_fork_events(children[0]); + children[1] = handle_fork_events(children[0], NULL); ATF_REQUIRE(children[1] > 0); ATF_REQUIRE(ptrace(PT_CONTINUE, children[0], (caddr_t)1, 0) != -1); @@ -819,7 +828,7 @@ ATF_TC_BODY(ptrace__follow_fork_parent_d ATF_REQUIRE((fpid = fork()) != -1); if (fpid == 0) { attach_fork_parent(cpipe); - follow_fork_parent(); + follow_fork_parent(false); } /* Parent process. */ @@ -846,7 +855,7 @@ ATF_TC_BODY(ptrace__follow_fork_parent_d /* Signal the fork parent to continue. */ close(cpipe[0]); - children[1] = handle_fork_events(children[0]); + children[1] = handle_fork_events(children[0], NULL); ATF_REQUIRE(children[1] > 0); ATF_REQUIRE(ptrace(PT_DETACH, children[0], (caddr_t)1, 0) != -1); @@ -952,6 +961,223 @@ ATF_TC_BODY(ptrace__getppid, tc) ATF_REQUIRE(WEXITSTATUS(status) == 1); } +/* + * Verify that pl_syscall_code in struct ptrace_lwpinfo for a new + * child process created via fork() reports the correct value. + */ +ATF_TC_WITHOUT_HEAD(ptrace__new_child_pl_syscall_code_fork); +ATF_TC_BODY(ptrace__new_child_pl_syscall_code_fork, tc) +{ + struct ptrace_lwpinfo pl[2]; + pid_t children[2], fpid, wpid; + int status; + + ATF_REQUIRE((fpid = fork()) != -1); + if (fpid == 0) { + trace_me(); + follow_fork_parent(false); + } + + /* Parent process. */ + children[0] = fpid; + + /* The first wait() should report the stop from SIGSTOP. */ + wpid = waitpid(children[0], &status, 0); + ATF_REQUIRE(wpid == children[0]); + ATF_REQUIRE(WIFSTOPPED(status)); + ATF_REQUIRE(WSTOPSIG(status) == SIGSTOP); + + ATF_REQUIRE(ptrace(PT_FOLLOW_FORK, children[0], NULL, 1) != -1); + + /* Continue the child ignoring the SIGSTOP. */ + ATF_REQUIRE(ptrace(PT_CONTINUE, children[0], (caddr_t)1, 0) != -1); + + /* Wait for both halves of the fork event to get reported. */ + children[1] = handle_fork_events(children[0], pl); + ATF_REQUIRE(children[1] > 0); + + ATF_REQUIRE((pl[0].pl_flags & PL_FLAG_SCX) != 0); + ATF_REQUIRE((pl[1].pl_flags & PL_FLAG_SCX) != 0); + ATF_REQUIRE(pl[0].pl_syscall_code == SYS_fork); + ATF_REQUIRE(pl[0].pl_syscall_code == pl[1].pl_syscall_code); + ATF_REQUIRE(pl[0].pl_syscall_narg == pl[1].pl_syscall_narg); + + ATF_REQUIRE(ptrace(PT_CONTINUE, children[0], (caddr_t)1, 0) != -1); + ATF_REQUIRE(ptrace(PT_CONTINUE, children[1], (caddr_t)1, 0) != -1); + + /* + * The child can't exit until the grandchild reports status, so the + * grandchild should report its exit first to the debugger. + */ + wpid = wait(&status); + ATF_REQUIRE(wpid == children[1]); + ATF_REQUIRE(WIFEXITED(status)); + ATF_REQUIRE(WEXITSTATUS(status) == 2); + + wpid = wait(&status); + ATF_REQUIRE(wpid == children[0]); + ATF_REQUIRE(WIFEXITED(status)); + ATF_REQUIRE(WEXITSTATUS(status) == 1); + + wpid = wait(&status); + ATF_REQUIRE(wpid == -1); + ATF_REQUIRE(errno == ECHILD); +} + +/* + * Verify that pl_syscall_code in struct ptrace_lwpinfo for a new + * child process created via vfork() reports the correct value. + */ +ATF_TC_WITHOUT_HEAD(ptrace__new_child_pl_syscall_code_vfork); +ATF_TC_BODY(ptrace__new_child_pl_syscall_code_vfork, tc) +{ + struct ptrace_lwpinfo pl[2]; + pid_t children[2], fpid, wpid; + int status; + + ATF_REQUIRE((fpid = fork()) != -1); + if (fpid == 0) { + trace_me(); + follow_fork_parent(true); + } + + /* Parent process. */ + children[0] = fpid; + + /* The first wait() should report the stop from SIGSTOP. */ + wpid = waitpid(children[0], &status, 0); + ATF_REQUIRE(wpid == children[0]); + ATF_REQUIRE(WIFSTOPPED(status)); + ATF_REQUIRE(WSTOPSIG(status) == SIGSTOP); + + ATF_REQUIRE(ptrace(PT_FOLLOW_FORK, children[0], NULL, 1) != -1); + + /* Continue the child ignoring the SIGSTOP. */ + ATF_REQUIRE(ptrace(PT_CONTINUE, children[0], (caddr_t)1, 0) != -1); + + /* Wait for both halves of the fork event to get reported. */ + children[1] = handle_fork_events(children[0], pl); + ATF_REQUIRE(children[1] > 0); + + ATF_REQUIRE((pl[0].pl_flags & PL_FLAG_SCX) != 0); + ATF_REQUIRE((pl[1].pl_flags & PL_FLAG_SCX) != 0); + ATF_REQUIRE(pl[0].pl_syscall_code == SYS_vfork); + ATF_REQUIRE(pl[0].pl_syscall_code == pl[1].pl_syscall_code); + ATF_REQUIRE(pl[0].pl_syscall_narg == pl[1].pl_syscall_narg); + + ATF_REQUIRE(ptrace(PT_CONTINUE, children[0], (caddr_t)1, 0) != -1); + ATF_REQUIRE(ptrace(PT_CONTINUE, children[1], (caddr_t)1, 0) != -1); + + /* + * The child can't exit until the grandchild reports status, so the + * grandchild should report its exit first to the debugger. + */ + wpid = wait(&status); + ATF_REQUIRE(wpid == children[1]); + ATF_REQUIRE(WIFEXITED(status)); + ATF_REQUIRE(WEXITSTATUS(status) == 2); + + wpid = wait(&status); + ATF_REQUIRE(wpid == children[0]); + ATF_REQUIRE(WIFEXITED(status)); + ATF_REQUIRE(WEXITSTATUS(status) == 1); + + wpid = wait(&status); + ATF_REQUIRE(wpid == -1); + ATF_REQUIRE(errno == ECHILD); +} + +static void * +simple_thread(void *arg __unused) +{ + + pthread_exit(NULL); +} + +/* + * Verify that pl_syscall_code in struct ptrace_lwpinfo for a new + * thread reports the correct value. + */ +ATF_TC_WITHOUT_HEAD(ptrace__new_child_pl_syscall_code_thread); +ATF_TC_BODY(ptrace__new_child_pl_syscall_code_thread, tc) +{ + struct ptrace_lwpinfo pl; + pid_t fpid, wpid; + lwpid_t main; + int status; + + ATF_REQUIRE((fpid = fork()) != -1); + if (fpid == 0) { + pthread_t thread; + + trace_me(); + + CHILD_REQUIRE(pthread_create(&thread, NULL, simple_thread, + NULL) == 0); + CHILD_REQUIRE(pthread_join(thread, NULL) == 0); + exit(1); + } + + /* The first wait() should report the stop from SIGSTOP. */ + wpid = waitpid(fpid, &status, 0); + ATF_REQUIRE(wpid == fpid); + ATF_REQUIRE(WIFSTOPPED(status)); + ATF_REQUIRE(WSTOPSIG(status) == SIGSTOP); + + ATF_REQUIRE(ptrace(PT_LWPINFO, wpid, (caddr_t)&pl, + sizeof(pl)) != -1); + main = pl.pl_lwpid; + + /* + * Continue the child ignoring the SIGSTOP and tracing all + * system call exits. + */ + ATF_REQUIRE(ptrace(PT_TO_SCX, fpid, (caddr_t)1, 0) != -1); + + /* + * Wait for the new thread to arrive. pthread_create() might + * invoke any number of system calls. For now we just wait + * for the new thread to arrive and make sure it reports a + * valid system call code. If ptrace grows thread event + * reporting then this test can be made more precise. + */ + for (;;) { + wpid = waitpid(fpid, &status, 0); + ATF_REQUIRE(wpid == fpid); + ATF_REQUIRE(WIFSTOPPED(status)); + ATF_REQUIRE(WSTOPSIG(status) == SIGTRAP); + + ATF_REQUIRE(ptrace(PT_LWPINFO, wpid, (caddr_t)&pl, + sizeof(pl)) != -1); + ATF_REQUIRE((pl.pl_flags & PL_FLAG_SCX) != 0); + ATF_REQUIRE(pl.pl_syscall_code != 0); + if (pl.pl_lwpid != main) + /* New thread seen. */ + break; + + ATF_REQUIRE(ptrace(PT_CONTINUE, fpid, (caddr_t)1, 0) == 0); + } + + /* Wait for the child to exit. */ + ATF_REQUIRE(ptrace(PT_CONTINUE, fpid, (caddr_t)1, 0) == 0); + for (;;) { + wpid = waitpid(fpid, &status, 0); + ATF_REQUIRE(wpid == fpid); + if (WIFEXITED(status)) + break; + + ATF_REQUIRE(WIFSTOPPED(status)); + ATF_REQUIRE(WSTOPSIG(status) == SIGTRAP); + ATF_REQUIRE(ptrace(PT_CONTINUE, fpid, (caddr_t)1, 0) == 0); + } + + ATF_REQUIRE(WEXITSTATUS(status) == 1); + + wpid = wait(&status); + ATF_REQUIRE(wpid == -1); + ATF_REQUIRE(errno == ECHILD); +} + ATF_TP_ADD_TCS(tp) { @@ -968,6 +1194,9 @@ ATF_TP_ADD_TCS(tp) ATF_TP_ADD_TC(tp, ptrace__follow_fork_parent_detached_unrelated_debugger); ATF_TP_ADD_TC(tp, ptrace__getppid); + ATF_TP_ADD_TC(tp, ptrace__new_child_pl_syscall_code_fork); + ATF_TP_ADD_TC(tp, ptrace__new_child_pl_syscall_code_vfork); + ATF_TP_ADD_TC(tp, ptrace__new_child_pl_syscall_code_thread); return (atf_no_error()); }
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