Use kldsym(2) to lookup symbol values. This avoids the kvm_mkdb juggling

and is module aware.  Yes, this means that kvm_nlist(3) will find symbols
in loaded modules.  The emulation of the nlist struct is pretty crude but
seems to work well enough for all the users in the tree that I found.

11 files changed, 60 insertions, 129 deletions

diff --git a/lib/libkvm/kvm.c b/lib/libkvm/kvm.c
index b35eceb..55c33f8 100644
--- a/lib/libkvm/kvm.c
+++ b/lib/libkvm/kvm.c
@@ -40,7 +40,7 @@
 static char sccsid[] = "@(#)kvm.c	8.2 (Berkeley) 2/13/94";
 #else
 static const char rcsid[] =
-  "$FreeBSD$";
+ "$FreeBSD$";
 #endif
 #endif /* LIBC_SCCS and not lint */
 
@@ -50,6 +50,7 @@ static const char rcsid[] =
 #include <sys/ioctl.h>
 #include <sys/stat.h>
 #include <sys/sysctl.h>
+#include <sys/linker.h>
 
 #include <vm/vm.h>
 #include <vm/vm_param.h>
@@ -58,7 +59,6 @@ static const char rcsid[] =
 #include <machine/vmparam.h>
 
 #include <ctype.h>
-#include <db.h>
 #include <fcntl.h>
 #include <kvm.h>
 #include <limits.h>
@@ -71,8 +71,6 @@ static const char rcsid[] =
 
 #include "kvm_private.h"
 
-static int kvm_dbopen __P((kvm_t *, const char *));
-
 char *
 kvm_geterr(kd)
 	kvm_t *kd;
@@ -180,7 +178,6 @@ _kvm_open(kd, uf, mf, flag, errout)
 	kd->pmfd = -1;
 	kd->nlfd = -1;
 	kd->vmst = 0;
-	kd->db = 0;
 	kd->procbase = 0;
 	kd->argspc = 0;
 	kd->argv = 0;
@@ -225,19 +222,6 @@ _kvm_open(kd, uf, mf, flag, errout)
 				goto failed;
 			}
 		}
-		/*
-		 * Open kvm nlist database.  We go ahead and do this
-		 * here so that we don't have to hold on to the kernel
-		 * path name.  Since a kvm application will surely do
-		 * a kvm_nlist(), this probably won't be a wasted effort.
-		 * If the database cannot be opened, open the namelist
-		 * argument so we revert to slow nlist() calls.
-		 */
-		if (kvm_dbopen(kd, uf) < 0 &&
-		    (kd->nlfd = open(uf, O_RDONLY, 0)) < 0) {
-			_kvm_syserr(kd, kd->program, "%s", uf);
-			goto failed;
-		}
 	} else {
 		/*
 		 * This is a crash dump.
@@ -314,8 +298,6 @@ kvm_close(kd)
 		error |= close(kd->vmfd);
 	if (kd->nlfd >= 0)
 		error |= close(kd->nlfd);
-	if (kd->db != 0)
-		error |= (kd->db->close)(kd->db);
 	if (kd->vmst)
 		_kvm_freevtop(kd);
 	if (kd->procbase != 0)
@@ -327,72 +309,6 @@ kvm_close(kd)
 	return (0);
 }
 
-/*
- * Set up state necessary to do queries on the kernel namelist
- * data base.  If the data base is out-of-data/incompatible with
- * given executable, set up things so we revert to standard nlist call.
- * Only called for live kernels.  Return 0 on success, -1 on failure.
- */
-static int
-kvm_dbopen(kd, uf)
-	kvm_t *kd;
-	const char *uf;
-{
-	char *cp;
-	DBT rec;
-	int dbversionlen;
-	struct nlist nitem;
-	char dbversion[_POSIX2_LINE_MAX];
-	char kversion[_POSIX2_LINE_MAX];
-	char dbname[MAXPATHLEN];
-
-	if ((cp = rindex(uf, '/')) != 0)
-		uf = cp + 1;
-
-	(void)snprintf(dbname, sizeof(dbname), "%skvm_%s.db", _PATH_VARDB, uf);
-	kd->db = dbopen(dbname, O_RDONLY, 0, DB_HASH, NULL);
-	if (kd->db == 0)
-		return (-1);
-	/*
-	 * read version out of database
-	 */
-	rec.data = VRS_KEY;
-	rec.size = sizeof(VRS_KEY) - 1;
-	if ((kd->db->get)(kd->db, (DBT *)&rec, (DBT *)&rec, 0))
-		goto close;
-	if (rec.data == 0 || rec.size > sizeof(dbversion))
-		goto close;
-
-	bcopy(rec.data, dbversion, rec.size);
-	dbversionlen = rec.size;
-	/*
-	 * Read version string from kernel memory.
-	 * Since we are dealing with a live kernel, we can call kvm_read()
-	 * at this point.
-	 */
-	rec.data = VRS_SYM;
-	rec.size = sizeof(VRS_SYM) - 1;
-	if ((kd->db->get)(kd->db, (DBT *)&rec, (DBT *)&rec, 0))
-		goto close;
-	if (rec.data == 0 || rec.size != sizeof(struct nlist))
-		goto close;
-	bcopy((char *)rec.data, (char *)&nitem, sizeof(nitem));
-	if (kvm_read(kd, (u_long)nitem.n_value, kversion, dbversionlen) !=
-	    dbversionlen)
-		goto close;
-	/*
-	 * If they match, we win - otherwise clear out kd->db so
-	 * we revert to slow nlist().
-	 */
-	if (bcmp(dbversion, kversion, dbversionlen) == 0)
-		return (0);
-close:
-	(void)(kd->db->close)(kd->db);
-	kd->db = 0;
-
-	return (-1);
-}
-
 int
 kvm_nlist(kd, nl)
 	kvm_t *kd;
@@ -400,44 +316,37 @@ kvm_nlist(kd, nl)
 {
 	register struct nlist *p;
 	register int nvalid;
+	struct kld_sym_lookup lookup;
 
 	/*
-	 * If we can't use the data base, revert to the
+	 * If we can't use the kld symbol lookup, revert to the
 	 * slow library call.
 	 */
-	if (kd->db == 0)
+	if (!ISALIVE(kd))
 		return (__fdnlist(kd->nlfd, nl));
 
 	/*
-	 * We can use the kvm data base.  Go through each nlist entry
-	 * and look it up with a db query.
+	 * We can use the kld lookup syscall.  Go through each nlist entry
+	 * and look it up with a kldsym(2) syscall.
 	 */
 	nvalid = 0;
 	for (p = nl; p->n_name && p->n_name[0]; ++p) {
-		register int len;
-		DBT rec;
-
-		if ((len = strlen(p->n_name)) > 4096) {
-			/* sanity */
-			_kvm_err(kd, kd->program, "symbol too large");
-			return (-1);
+		lookup.version = sizeof(lookup);
+		lookup.symname = p->n_name;
+		lookup.symvalue = 0;
+		lookup.symsize = 0;
+
+		if (lookup.symname[0] == '_')
+			lookup.symname++;
+
+		if (kldsym(0, KLDSYM_LOOKUP, &lookup) != -1) {
+			p->n_type = N_TEXT;
+			p->n_other = 0;
+			p->n_desc = 0;
+			p->n_value = lookup.symvalue;
+			++nvalid;
+			/* lookup.symsize */
 		}
-		rec.data = p->n_name;
-		rec.size = len;
-		if ((kd->db->get)(kd->db, (DBT *)&rec, (DBT *)&rec, 0))
-			continue;
-		if (rec.data == 0 || rec.size != sizeof(struct nlist))
-			continue;
-		++nvalid;
-		/*
-		 * Avoid alignment issues.
-		 */
-		bcopy((char *)&((struct nlist *)rec.data)->n_type,
-		      (char *)&p->n_type,
-		      sizeof(p->n_type));
-		bcopy((char *)&((struct nlist *)rec.data)->n_value,
-		      (char *)&p->n_value,
-		      sizeof(p->n_value));
 	}
 	/*
 	 * Return the number of entries that weren't found.
diff --git a/lib/libkvm/kvm_alpha.c b/lib/libkvm/kvm_alpha.c
index 391a955..98417a0 100644
--- a/lib/libkvm/kvm_alpha.c
+++ b/lib/libkvm/kvm_alpha.c
@@ -42,7 +42,6 @@
 #include <vm/vm_param.h>
 
 #include <limits.h>
-#include <db.h>
 #include <stdlib.h>
 #include <machine/pmap.h>
 #include "kvm_private.h"
diff --git a/lib/libkvm/kvm_amd64.c b/lib/libkvm/kvm_amd64.c
index d36b922..0b727fd 100644
--- a/lib/libkvm/kvm_amd64.c
+++ b/lib/libkvm/kvm_amd64.c
@@ -36,7 +36,12 @@
  */
 
 #if defined(LIBC_SCCS) && !defined(lint)
+#if 0
 static char sccsid[] = "@(#)kvm_hp300.c	8.1 (Berkeley) 6/4/93";
+#else
+static const char rcsid[] =
+ "$FreeBSD$";
+#endif
 #endif /* LIBC_SCCS and not lint */
 
 /*
@@ -57,7 +62,6 @@ static char sccsid[] = "@(#)kvm_hp300.c	8.1 (Berkeley) 6/4/93";
 #include <vm/vm_param.h>
 
 #include <limits.h>
-#include <db.h>
 
 #include "kvm_private.h"
 
diff --git a/lib/libkvm/kvm_file.c b/lib/libkvm/kvm_file.c
index 4af6b71..a80ba8e 100644
--- a/lib/libkvm/kvm_file.c
+++ b/lib/libkvm/kvm_file.c
@@ -32,7 +32,12 @@
  */
 
 #if defined(LIBC_SCCS) && !defined(lint)
+#if 0
 static char sccsid[] = "@(#)kvm_file.c	8.1 (Berkeley) 6/4/93";
+#else
+static const char rcsid[] =
+ "$FreeBSD$";
+#endif
 #endif /* LIBC_SCCS and not lint */
 
 /*
diff --git a/lib/libkvm/kvm_getloadavg.c b/lib/libkvm/kvm_getloadavg.c
index 3368e63..7963831 100644
--- a/lib/libkvm/kvm_getloadavg.c
+++ b/lib/libkvm/kvm_getloadavg.c
@@ -32,7 +32,12 @@
  */
 
 #if defined(LIBC_SCCS) && !defined(lint)
+#if 0
 static char sccsid[] = "@(#)kvm_getloadavg.c	8.1 (Berkeley) 6/4/93";
+#else
+static const char rcsid[] =
+ "$FreeBSD$";
+#endif
 #endif /* LIBC_SCCS and not lint */
 
 #include <sys/param.h>
@@ -43,7 +48,6 @@ static char sccsid[] = "@(#)kvm_getloadavg.c	8.1 (Berkeley) 6/4/93";
 #include <vm/vm_param.h>
 
 #include <stdlib.h>
-#include <db.h>
 #include <fcntl.h>
 #include <limits.h>
 #include <nlist.h>
diff --git a/lib/libkvm/kvm_getswapinfo.c b/lib/libkvm/kvm_getswapinfo.c
index 05aeedf..4c85e82 100644
--- a/lib/libkvm/kvm_getswapinfo.c
+++ b/lib/libkvm/kvm_getswapinfo.c
@@ -28,7 +28,6 @@ static const char rcsid[] =
 #include <err.h>
 #include <fcntl.h>
 #include <kvm.h>
-#include <limits.h>
 #include <nlist.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/lib/libkvm/kvm_i386.c b/lib/libkvm/kvm_i386.c
index d36b922..0b727fd 100644
--- a/lib/libkvm/kvm_i386.c
+++ b/lib/libkvm/kvm_i386.c
@@ -36,7 +36,12 @@
  */
 
 #if defined(LIBC_SCCS) && !defined(lint)
+#if 0
 static char sccsid[] = "@(#)kvm_hp300.c	8.1 (Berkeley) 6/4/93";
+#else
+static const char rcsid[] =
+ "$FreeBSD$";
+#endif
 #endif /* LIBC_SCCS and not lint */
 
 /*
@@ -57,7 +62,6 @@ static char sccsid[] = "@(#)kvm_hp300.c	8.1 (Berkeley) 6/4/93";
 #include <vm/vm_param.h>
 
 #include <limits.h>
-#include <db.h>
 
 #include "kvm_private.h"
 
diff --git a/lib/libkvm/kvm_nlist.3 b/lib/libkvm/kvm_nlist.3
index f5611b3..b01930b 100644
--- a/lib/libkvm/kvm_nlist.3
+++ b/lib/libkvm/kvm_nlist.3
@@ -60,12 +60,10 @@ Each symbol is looked up using the n_name field, and if found, the
 corresponding n_type and n_value fields are filled in.  These fields are set
 to 0 if the symbol is not found.
 .Pp
-The program
-.Xr kvm_mkdb 8
-builds a database from the running kernel's namelist.
-If the database matches the opened kernel,
-.Fn kvm_nlist
-uses it to speed lookups.
+.Xr kldsym 2
+is used to locate the symbol.  This is a less than perfect emulation
+of the nlist values but has the advantage of being aware of kernel modules
+and is reasonably fast.
 .Sh RETURN VALUES
 The
 .Fn kvm_nlist
@@ -76,6 +74,7 @@ If the kernel symbol table was unreadable, -1 is returned.
 .It Pa /var/db/kvm_kernel.db
 .El
 .Sh SEE ALSO
+.Xr kldsym 2 ,
 .Xr kvm 3 ,
 .Xr kvm_close 3 ,
 .Xr kvm_getargv 3 ,
@@ -85,5 +84,4 @@ If the kernel symbol table was unreadable, -1 is returned.
 .Xr kvm_open 3 ,
 .Xr kvm_openfiles 3 ,
 .Xr kvm_read 3 ,
-.Xr kvm_write 3 ,
-.Xr kvm_mkdb 8
+.Xr kvm_write 3
diff --git a/lib/libkvm/kvm_private.h b/lib/libkvm/kvm_private.h
index 2d6d07f..402b9ee 100644
--- a/lib/libkvm/kvm_private.h
+++ b/lib/libkvm/kvm_private.h
@@ -35,6 +35,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)kvm_private.h	8.1 (Berkeley) 6/4/93
+ * $FreeBSD$
  */
 
 struct __kvm {
@@ -46,7 +47,6 @@ struct __kvm {
 	const char *program;
 	char	*errp;		/* XXX this can probably go away */
 	char	errbuf[_POSIX2_LINE_MAX];
-	DB	*db;
 #define ISALIVE(kd) ((kd)->vmfd >= 0)
 	int	pmfd;		/* physical memory file (or crashdump) */
 	int	vmfd;		/* virtual memory file (-1 if crashdump) */
diff --git a/lib/libkvm/kvm_proc.c b/lib/libkvm/kvm_proc.c
index feba974..3490bd4 100644
--- a/lib/libkvm/kvm_proc.c
+++ b/lib/libkvm/kvm_proc.c
@@ -70,7 +70,6 @@ static char sccsid[] = "@(#)kvm_proc.c	8.3 (Berkeley) 9/23/93";
 
 #include <limits.h>
 #include <memory.h>
-#include <db.h>
 #include <paths.h>
 
 #include "kvm_private.h"
@@ -675,6 +674,12 @@ kvm_getargv(kd, kp, nchr)
 	static char **bufp;
 	static int argc;
 
+	if (!ISALIVE(kd)) {
+		_kvm_err(kd, kd->program,
+		    "cannot read user space from dead kernel");
+		return (0);
+	}
+
 	if (!buflen) {
 		l = sizeof(buflen);
 		i = sysctlbyname("kern.ps_arg_cache_limit", 
diff --git a/lib/libkvm/kvm_sparc.c b/lib/libkvm/kvm_sparc.c
index a7b9594..7a538d8 100644
--- a/lib/libkvm/kvm_sparc.c
+++ b/lib/libkvm/kvm_sparc.c
@@ -36,7 +36,12 @@
  */
 
 #if defined(LIBC_SCCS) && !defined(lint)
+#if 0
 static char sccsid[] = "@(#)kvm_sparc.c	8.1 (Berkeley) 6/4/93";
+#else
+static const char rcsid[] =
+ "$FreeBSD$";
+#endif
 #endif /* LIBC_SCCS and not lint */
 
 /*
@@ -56,7 +61,6 @@ static char sccsid[] = "@(#)kvm_sparc.c	8.1 (Berkeley) 6/4/93";
 #include <vm/vm_param.h>
 
 #include <limits.h>
-#include <db.h>
 
 #include "kvm_private.h"