Re: [PATCH] Use kinfo_getvmmap () on FreeBSD to enumerate memory regions.

[John Baldwin <jhb@freebsd.org>]

On Friday, March 06, 2015 10:41:19 PM Pedro Alves wrote:
> On 03/06/2015 09:06 PM, John Baldwin wrote:
> > On Friday, March 06, 2015 07:49:23 PM Pedro Alves wrote:
> >>> +# On FreeBSD we may need libutil for kinfo_getvmmap (used by fbsd-nat.c).
> >>> +AC_CHECK_LIB(util, kinfo_getvmmap,
> >>> +  [AC_DEFINE(HAVE_KINFO_GETVMMAP, 1,
> >>> +            [Define to 1 if your system has the kinfo_getvmmap function.
> >>> ])]) +
> >>
> >> Isn't
> >>
> >>  AC_SEARCH_LIBS(kinfo_getvmmap, [util])
> >>
> >> pretty much the same?
> > 
> > Might be, I wasn't sure from reading the autoconf docs that this would add the 
> > appropriate define.  I'll certainly try it and if it works I'm happier to use 
> > the simpler form.

I ended up needing to include AC_DEFINE() still, but AC_SEARCH_LIBS() worked
fine.

Updated patch:

Use kinfo_getvmmap from libutil on FreeBSD to enumerate memory
regions in a running process instead of /proc/<pid>/map.  FreeBSD systems
do not mount procfs by default, but kinfo_getvmmap uses a sysctl that
is always available.

Skip memory regions for devices as well as regions an application has
requested to not be dumped via the MAP_NOCORE flag to mmap or
MADV_NOCORE advice to madvise.

gdb/ChangeLog:

	* configure.ac: AC_CHECK_LIB(util, kinfo_getvmmap).
	* configure: Regenerate.
	* config.in: Regenerate.
	* fbsd-nat.c [!HAVE_KINFO_GETVMMAP] (fbsd_read_mapping): Don't
        define.
	(fbsd_find_memory_regions): Use kinfo_getvmmap to
	enumerate memory regions if present.

diff --git a/gdb/configure.ac b/gdb/configure.ac
index 4a0b6a3..38747e8 100644
--- a/gdb/configure.ac
+++ b/gdb/configure.ac
@@ -537,6 +537,11 @@ AM_ZLIB
 # On HP/UX we may need libxpdl for dlgetmodinfo (used by solib-pa64.c).
 AC_SEARCH_LIBS(dlgetmodinfo, [dl xpdl])
 
+# On FreeBSD we may need libutil for kinfo_getvmmap (used by fbsd-nat.c).
+AC_SEARCH_LIBS(kinfo_getvmmap, util,
+  [AC_DEFINE(HAVE_KINFO_GETVMMAP, 1,
+            [Define to 1 if your system has the kinfo_getvmmap function. ])])
+
 AM_ICONV
 
 # GDB may fork/exec the iconv program to get the list of supported character
diff --git a/gdb/fbsd-nat.c b/gdb/fbsd-nat.c
index 062eede..1ce197d 100644
--- a/gdb/fbsd-nat.c
+++ b/gdb/fbsd-nat.c
@@ -26,6 +26,10 @@
 #include <sys/types.h>
 #include <sys/procfs.h>
 #include <sys/sysctl.h>
+#ifdef HAVE_KINFO_GETVMMAP
+#include <sys/user.h>
+#include <libutil.h>
+#endif
 
 #include "elf-bfd.h"
 #include "fbsd-nat.h"
@@ -62,6 +66,64 @@ fbsd_pid_to_exec_file (struct target_ops *self, int pid)
   return NULL;
 }
 
+#ifdef HAVE_KINFO_GETVMMAP
+/* Iterate over all the memory regions in the current inferior,
+   calling FUNC for each memory region.  OBFD is passed as the last
+   argument to FUNC.  */
+
+int
+fbsd_find_memory_regions (struct target_ops *self,
+			  find_memory_region_ftype func, void *obfd)
+{
+  pid_t pid = ptid_get_pid (inferior_ptid);
+  struct kinfo_vmentry *vmentl, *kve;
+  uint64_t size;
+  struct cleanup *cleanup;
+  int i, nitems;
+
+  vmentl = kinfo_getvmmap (pid, &nitems);
+  if (vmentl == NULL)
+    perror_with_name (_("Couldn't fetch VM map entries."));
+  cleanup = make_cleanup (free, vmentl);
+
+  for (i = 0; i < nitems; i++)
+    {
+      kve = &vmentl[i];
+
+      /* Skip unreadable segments and those where MAP_NOCORE has been set.  */
+      if (!(kve->kve_protection & KVME_PROT_READ)
+	  || kve->kve_flags & KVME_FLAG_NOCOREDUMP)
+	continue;
+
+      /* Skip segments with an invalid type.  */
+      if (kve->kve_type != KVME_TYPE_DEFAULT
+	  && kve->kve_type != KVME_TYPE_VNODE
+	  && kve->kve_type != KVME_TYPE_SWAP
+	  && kve->kve_type != KVME_TYPE_PHYS)
+	continue;
+
+      size = kve->kve_end - kve->kve_start;
+      if (info_verbose)
+	{
+	  fprintf_filtered (gdb_stdout, 
+			    "Save segment, %ld bytes at %s (%c%c%c)\n",
+			    (long) size,
+			    paddress (target_gdbarch (), kve->kve_start),
+			    kve->kve_protection & KVME_PROT_READ ? 'r' : '-',
+			    kve->kve_protection & KVME_PROT_WRITE ? 'w' : '-',
+			    kve->kve_protection & KVME_PROT_EXEC ? 'x' : '-');
+	}
+
+      /* Invoke the callback function to create the corefile segment.
+	 Pass MODIFIED as true, we do not know the real modification state.  */
+      func (kve->kve_start, size, kve->kve_protection & KVME_PROT_READ,
+	    kve->kve_protection & KVME_PROT_WRITE,
+	    kve->kve_protection & KVME_PROT_EXEC, 1, obfd);
+    }
+  do_cleanups (cleanup);
+  return 0;
+}
+#else
 static int
 fbsd_read_mapping (FILE *mapfile, unsigned long *start, unsigned long *end,
 		   char *protection)
@@ -137,3 +199,4 @@ fbsd_find_memory_regions (struct target_ops *self,
   do_cleanups (cleanup);
   return 0;
 }
+#endif
-- 
2.2.1