libdtrace: add support for lazyload mode.

Passing "-x lazyload" to dtrace -G during compilation causes dtrace(1) to
not link drti.o into the output object file, so the USDT probes are not created
during process startup. Instead, dtrace(1) will automatically discover and
create probes on the process' behalf when attaching.

Differential Revision:	https://reviews.freebsd.org/D2203
Reviewed by:		rpaulo
MFC after:		1 month

cddl/contrib/opensolaris/lib/libdtrace/common/drti.c

@@ -147,6 +147,9 @@ dtrace_dof_init(void)
 
 	dh.dofhp_dof = (uintptr_t)dof;
 	dh.dofhp_addr = elf->e_type == ET_DYN ? (uintptr_t) lmp->l_addr : 0;
+#ifdef __FreeBSD__
+	dh.dofhp_pid = getpid();
+#endif
 
 	if (lmid == 0) {
 		(void) snprintf(dh.dofhp_mod, sizeof (dh.dofhp_mod),
@@ -184,7 +187,7 @@ dtrace_dof_init(void)
 	else {
 		dprintf(1, "DTrace ioctl succeeded for DOF at %p\n", dof);
 #ifdef __FreeBSD__
-		gen = dh.gen;
+		gen = dh.dofhp_gen;
 #endif
 	}
 

cddl/contrib/opensolaris/lib/libdtrace/common/dt_link.c

@@ -1785,11 +1785,17 @@ dtrace_program_link(dtrace_hdl_t *dtp, dtrace_prog_t *pgp, uint_t dflags,
 		    "failed to open %s: %s", file, strerror(errno)));
 	}
 #else
-	snprintf(tfile, sizeof(tfile), "%s.XXXXXX", file);
-	if ((fd = mkstemp(tfile)) == -1)
-		return (dt_link_error(dtp, NULL, -1, NULL,
-		    "failed to create temporary file %s: %s",
-		    tfile, strerror(errno)));
+	if (dtp->dt_lazyload) {
+		if ((fd = open(file, O_RDWR | O_CREAT | O_TRUNC, 0666)) < 0)
+			return (dt_link_error(dtp, NULL, -1, NULL,
+			    "failed to open %s: %s", file, strerror(errno)));
+	} else {
+		snprintf(tfile, sizeof(tfile), "%s.XXXXXX", file);
+		if ((fd = mkstemp(tfile)) == -1)
+			return (dt_link_error(dtp, NULL, -1, NULL,
+			    "failed to create temporary file %s: %s",
+			    tfile, strerror(errno)));
+	}
 #endif
 
 	/*

cddl/contrib/opensolaris/lib/libdtrace/common/dt_pid.c

@@ -44,11 +44,16 @@
 #include <dt_program.h>
 #include <dt_pid.h>
 #include <dt_string.h>
-#ifndef illumos
-#include <libproc_compat.h>
-#endif
 #include <dt_module.h>
 
+#ifndef illumos
+#include <sys/sysctl.h>
+#include <unistd.h>
+#include <libproc_compat.h>
+#include <libelf.h>
+#include <gelf.h>
+#endif
+
 typedef struct dt_pid_probe {
 	dtrace_hdl_t *dpp_dtp;
 	dt_pcb_t *dpp_pcb;
@@ -566,6 +571,12 @@ dt_pid_usdt_mapping(void *data, const prmap_t *pmp, const char *oname)
 	prsyminfo_t sip;
 	dof_helper_t dh;
 	GElf_Half e_type;
+#ifdef __FreeBSD__
+	dof_hdr_t hdr;
+	size_t sz;
+	uint64_t dofmax;
+	void *dof;
+#endif
 	const char *mname;
 	const char *syms[] = { "___SUNW_dof", "__SUNW_dof" };
 	int i, fd = -1;
@@ -595,17 +606,61 @@ dt_pid_usdt_mapping(void *data, const prmap_t *pmp, const char *oname)
 			continue;
 		}
 
+#ifdef __FreeBSD__
+		dh.dofhp_addr = (e_type == ET_EXEC) ? 0 : pmp->pr_vaddr;
+		if (Pread(P, &hdr, sizeof (hdr), sym.st_value) !=
+		    sizeof (hdr)) {
+			dt_dprintf("read of DOF header failed\n");
+			continue;
+		}
+
+		sz = sizeof(dofmax);
+		if (sysctlbyname("kern.dtrace.dof_maxsize", &dofmax, &sz,
+		    NULL, 0) != 0) {
+			dt_dprintf("failed to read dof_maxsize: %s\n",
+			    strerror(errno));
+			continue;
+		}
+		if (dofmax < hdr.dofh_loadsz) {
+			dt_dprintf("DOF load size exceeds maximum\n");
+			continue;
+		}
+
+		if ((dof = malloc(hdr.dofh_loadsz)) == NULL)
+			return (-1);
+
+		if (Pread(P, dof, hdr.dofh_loadsz, sym.st_value) !=
+		    hdr.dofh_loadsz) {
+			free(dof);
+			dt_dprintf("read of DOF section failed\n");
+			continue;
+		}
+
+		dh.dofhp_dof = (uintptr_t)dof;
+		dh.dofhp_pid = proc_getpid(P);
+
+		dt_pid_objname(dh.dofhp_mod, sizeof (dh.dofhp_mod),
+		    sip.prs_lmid, mname);
+
+		if (fd == -1 &&
+		    (fd = open("/dev/dtrace/helper", O_RDWR, 0)) < 0) {
+			dt_dprintf("open of helper device failed: %s\n",
+			    strerror(errno));
+			free(dof);
+			return (-1); /* errno is set for us */
+		}
+
+		if (ioctl(fd, DTRACEHIOC_ADDDOF, &dh, sizeof (dh)) < 0)
+			dt_dprintf("DOF was rejected for %s\n", dh.dofhp_mod);
+
+		free(dof);
+#else
 		dh.dofhp_dof = sym.st_value;
 		dh.dofhp_addr = (e_type == ET_EXEC) ? 0 : pmp->pr_vaddr;
 
 		dt_pid_objname(dh.dofhp_mod, sizeof (dh.dofhp_mod),
-#ifdef illumos
 		    sip.prs_lmid, mname);
-#else
-		    0, mname);
-#endif
 
-#ifdef illumos
 		if (fd == -1 &&
 		    (fd = pr_open(P, "/dev/dtrace/helper", O_RDWR, 0)) < 0) {
 			dt_dprintf("pr_open of helper device failed: %s\n",
@@ -618,8 +673,10 @@ dt_pid_usdt_mapping(void *data, const prmap_t *pmp, const char *oname)
 #endif
 	}
 
-#ifdef illumos
 	if (fd != -1)
+#ifdef __FreeBSD__
+		(void) close(fd);
+#else
 		(void) pr_close(P, fd);
 #endif
 
@@ -634,7 +691,6 @@ dt_pid_create_usdt_probes(dtrace_probedesc_t *pdp, dtrace_hdl_t *dtp,
 	int ret = 0;
 
 	assert(DT_MUTEX_HELD(&dpr->dpr_lock));
-#ifdef illumos
 	(void) Pupdate_maps(P);
 	if (Pobject_iter(P, dt_pid_usdt_mapping, P) != 0) {
 		ret = -1;
@@ -646,9 +702,6 @@ dt_pid_create_usdt_probes(dtrace_probedesc_t *pdp, dtrace_hdl_t *dtp,
 		    (int)proc_getpid(P), strerror(errno));
 #endif
 	}
-#else
-	ret = 0;
-#endif
 
 	/*
 	 * Put the module name in its canonical form.

cddl/lib/libdtrace/libproc_compat.h

@@ -59,6 +59,6 @@
 #define	Pstate proc_state
 #define	Psymbol_iter_by_addr proc_iter_symbyaddr
 #define	Punsetflags proc_clearflags
-#define	Pupdate_maps(p) do { } while (0)
+#define	Pupdate_maps proc_rdagent
 #define	Pupdate_syms proc_updatesyms
 #define	Pxecbkpt proc_bkptexec

sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c

@@ -15374,13 +15374,15 @@ dtrace_helper_action_destroy(dtrace_helper_action_t *helper,
 }
 
 static int
-dtrace_helper_destroygen(int gen)
+dtrace_helper_destroygen(dtrace_helpers_t *help, int gen)
 {
 	proc_t *p = curproc;
-	dtrace_helpers_t *help = p->p_dtrace_helpers;
 	dtrace_vstate_t *vstate;
 	int i;
 
+	if (help == NULL)
+		help = p->p_dtrace_helpers;
+
 	ASSERT(MUTEX_HELD(&dtrace_lock));
 
 	if (help == NULL || gen > help->dthps_generation)
@@ -15478,9 +15480,9 @@ dtrace_helper_validate(dtrace_helper_action_t *helper)
 }
 
 static int
-dtrace_helper_action_add(int which, dtrace_ecbdesc_t *ep)
+dtrace_helper_action_add(int which, dtrace_ecbdesc_t *ep,
+    dtrace_helpers_t *help)
 {
-	dtrace_helpers_t *help;
 	dtrace_helper_action_t *helper, *last;
 	dtrace_actdesc_t *act;
 	dtrace_vstate_t *vstate;
@@ -15490,7 +15492,6 @@ dtrace_helper_action_add(int which, dtrace_ecbdesc_t *ep)
 	if (which < 0 || which >= DTRACE_NHELPER_ACTIONS)
 		return (EINVAL);
 
-	help = curproc->p_dtrace_helpers;
 	last = help->dthps_actions[which];
 	vstate = &help->dthps_vstate;
 
@@ -15614,15 +15615,12 @@ dtrace_helper_provider_register(proc_t *p, dtrace_helpers_t *help,
 }
 
 static int
-dtrace_helper_provider_add(dof_helper_t *dofhp, int gen)
+dtrace_helper_provider_add(dof_helper_t *dofhp, dtrace_helpers_t *help, int gen)
 {
-	dtrace_helpers_t *help;
 	dtrace_helper_provider_t *hprov, **tmp_provs;
 	uint_t tmp_maxprovs, i;
 
 	ASSERT(MUTEX_HELD(&dtrace_lock));
-
-	help = curproc->p_dtrace_helpers;
 	ASSERT(help != NULL);
 
 	/*
@@ -15914,13 +15912,28 @@ dtrace_helper_slurp(dof_hdr_t *dof, dof_helper_t *dhp)
 	dtrace_helpers_t *help;
 	dtrace_vstate_t *vstate;
 	dtrace_enabling_t *enab = NULL;
+	proc_t *p = curproc;
 	int i, gen, rv, nhelpers = 0, nprovs = 0, destroy = 1;
 	uintptr_t daddr = (uintptr_t)dof;
 
 	ASSERT(MUTEX_HELD(&dtrace_lock));
 
-	if ((help = curproc->p_dtrace_helpers) == NULL)
-		help = dtrace_helpers_create(curproc);
+#ifdef __FreeBSD__
+	if (dhp->dofhp_pid != p->p_pid) {
+		if ((p = pfind(dhp->dofhp_pid)) == NULL)
+			return (-1);
+		if (!P_SHOULDSTOP(p) ||
+		    (p->p_flag & P_TRACED) == 0 ||
+		    p->p_pptr->p_pid != curproc->p_pid) {
+			PROC_UNLOCK(p);
+			return (-1);
+		}
+		PROC_UNLOCK(p);
+	}
+#endif
+
+	if ((help = p->p_dtrace_helpers) == NULL)
+		help = dtrace_helpers_create(p);
 
 	vstate = &help->dthps_vstate;
 
@@ -15968,12 +15981,13 @@ dtrace_helper_slurp(dof_hdr_t *dof, dof_helper_t *dhp)
 			continue;
 
 		if ((rv = dtrace_helper_action_add(DTRACE_HELPER_ACTION_USTACK,
-		    ep)) != 0) {
+		    ep, help)) != 0) {
 			/*
 			 * Adding this helper action failed -- we are now going
 			 * to rip out the entire generation and return failure.
 			 */
-			(void) dtrace_helper_destroygen(help->dthps_generation);
+			(void) dtrace_helper_destroygen(help,
+			    help->dthps_generation);
 			dtrace_enabling_destroy(enab);
 			dtrace_dof_destroy(dof);
 			return (-1);
@@ -15990,9 +16004,9 @@ dtrace_helper_slurp(dof_hdr_t *dof, dof_helper_t *dhp)
 
 	if (dhp != NULL && nprovs > 0) {
 		dhp->dofhp_dof = (uint64_t)(uintptr_t)dof;
-		if (dtrace_helper_provider_add(dhp, gen) == 0) {
+		if (dtrace_helper_provider_add(dhp, help, gen) == 0) {
 			mutex_exit(&dtrace_lock);
-			dtrace_helper_provider_register(curproc, help, dhp);
+			dtrace_helper_provider_register(p, help, dhp);
 			mutex_enter(&dtrace_lock);
 
 			destroy = 0;
@@ -16956,7 +16970,7 @@ dtrace_ioctl_helper(int cmd, intptr_t arg, int *rv)
 
 	case DTRACEHIOC_REMOVE: {
 		mutex_enter(&dtrace_lock);
-		rval = dtrace_helper_destroygen(arg);
+		rval = dtrace_helper_destroygen(NULL, arg);
 		mutex_exit(&dtrace_lock);
 
 		return (rval);

sys/cddl/contrib/opensolaris/uts/common/sys/dtrace.h

@@ -1423,8 +1423,9 @@ typedef struct dof_helper {
 	char dofhp_mod[DTRACE_MODNAMELEN];	/* executable or library name */
 	uint64_t dofhp_addr;			/* base address of object */
 	uint64_t dofhp_dof;			/* address of helper DOF */
-#ifndef illumos
-	int gen;
+#ifdef __FreeBSD__
+	pid_t dofhp_pid;			/* target process ID */
+	int dofhp_gen;
 #endif
 } dof_helper_t;
 

sys/cddl/dev/dtrace/dtrace_ioctl.c

@@ -32,9 +32,9 @@ static int
 dtrace_ioctl_helper(struct cdev *dev, u_long cmd, caddr_t addr, int flags,
     struct thread *td)
 {
-	int rval;
 	dof_helper_t *dhp = NULL;
 	dof_hdr_t *dof = NULL;
+	int rval;
 
 	switch (cmd) {
 	case DTRACEHIOC_ADDDOF:
@@ -51,7 +51,7 @@ dtrace_ioctl_helper(struct cdev *dev, u_long cmd, caddr_t addr, int flags,
 		mutex_enter(&dtrace_lock);
 		if ((rval = dtrace_helper_slurp((dof_hdr_t *)dof, dhp)) != -1) {
 			if (dhp) {
-				dhp->gen = rval;
+				dhp->dofhp_gen = rval;
 				copyout(dhp, addr, sizeof(*dhp));
 			}
 			rval = 0;
@@ -59,10 +59,11 @@ dtrace_ioctl_helper(struct cdev *dev, u_long cmd, caddr_t addr, int flags,
 			rval = EINVAL;
 		}
 		mutex_exit(&dtrace_lock);
+
 		return (rval);
 	case DTRACEHIOC_REMOVE:
 		mutex_enter(&dtrace_lock);
-		rval = dtrace_helper_destroygen((int)*addr);
+		rval = dtrace_helper_destroygen(NULL, (int)*addr);
 		mutex_exit(&dtrace_lock);
 
 		return (rval);