[PATCH v5] Generate NT_PROCSTAT_{AUXV,VMMAP,PS_STRINGS} in FreeBSD coredumps

Simon Ser
2018-08-23T17:11:10Z

gcore generates NT_AUXV and NT_FILE notes for Linux targets. On
FreeBSD auxv is stored in a NT_PROCSTAT_AUXV section, virtual memory
mappings are stored in a NT_PROCSTAT_VMMAP and both are prefixed with
the struct size.

2018-08-23 Simon Ser <contact@emersion.fr>
* target.h (enum target_object): add FreeBSD-specific
TARGET_OBJECT_FREEBSD_VMMAP and TARGET_OBJECT_FREEBSD_PS_STRINGS
* fbsd-nat.c (fbsd_nat_target::xfer_partial): add support for
TARGET_OBJECT_FREEBSD_VMMAP and TARGET_OBJECT_FREEBSD_PS_STRINGS
* fbsd-tdep.c (fbsd_make_corefile_notes): write NT_PROCSTAT_AUXV,
NT_PROCSTAT_VMMAP and NT_PROCSTAT_PS_STRINGS notes
---

Changes from v4 to v5:
- Fixed buflen too large before sysctl

gdb/fbsd-nat.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++
gdb/fbsd-tdep.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++
gdb/target.h | 4 ++++
3 files changed, 113 insertions(+)

diff --git a/gdb/fbsd-nat.c b/gdb/fbsd-nat.c
index 115deac0..3c1904a1 100644
--- a/gdb/fbsd-nat.c
+++ b/gdb/fbsd-nat.c
@@ -751,6 +751,61 @@ fbsd_nat_target::xfer_partial (enum target_object object,
}
return TARGET_XFER_E_IO;
}
+ case TARGET_OBJECT_FREEBSD_VMMAP:
+ case TARGET_OBJECT_FREEBSD_PS_STRINGS:
+ {
+ gdb::byte_vector buf_storage;
+ gdb_byte *buf;
+ size_t buflen;
+ int mib[4];
+
+ int proc_target;
+ uint32_t struct_size;
+ switch (object)
+ {
+ case TARGET_OBJECT_FREEBSD_VMMAP:
+ proc_target = KERN_PROC_VMMAP;
+ struct_size = sizeof (struct kinfo_vmentry);
+ break;
+ case TARGET_OBJECT_FREEBSD_PS_STRINGS:
+ proc_target = KERN_PROC_PS_STRINGS;
+ struct_size = sizeof (void *);
+ break;
+ }
+
+ if (writebuf != NULL)
+ return TARGET_XFER_E_IO;
+
+ mib[0] = CTL_KERN;
+ mib[1] = KERN_PROC;
+ mib[2] = proc_target;
+ mib[3] = pid;
+
+ if (sysctl (mib, 4, NULL, &buflen, NULL, 0) != 0)
+ return TARGET_XFER_E_IO;
+ buflen += sizeof (struct_size);
+
+ if (offset >= buflen)
+ {
+ *xfered_len = 0;
+ return TARGET_XFER_EOF;
+ }
+
+ buf_storage.resize (buflen);
+ buf = buf_storage.data ();
+
+ memcpy (buf, &struct_size, sizeof (struct_size));
+ buflen -= sizeof (struct_size);
+ if (sysctl (mib, 4, buf + sizeof (struct_size), &buflen, NULL, 0) != 0)
+ return TARGET_XFER_E_IO;
+ buflen += sizeof (struct_size);
+
+ if (offset + len > buflen)
+ len = buflen - offset;
+ memcpy (readbuf, buf + offset, len);
+ *xfered_len = len;
+ return TARGET_XFER_OK;
+ }
default:
return inf_ptrace_target::xfer_partial (object, annex,
readbuf, writebuf, offset,
diff --git a/gdb/fbsd-tdep.c b/gdb/fbsd-tdep.c
index 9cea0098..9242c244 100644
--- a/gdb/fbsd-tdep.c
+++ b/gdb/fbsd-tdep.c
@@ -512,6 +512,23 @@ fbsd_corefile_thread (struct thread_info *info,
args->note_size, args->stop_signal);
}

+static gdb::optional<gdb::byte_vector>
+fbsd_make_note_desc (enum target_object object, uint32_t structsize)
+{
+ gdb::optional<gdb::byte_vector> buf =
+ target_read_alloc (current_top_target (), object, NULL);
+ if (!buf || buf->empty ())
+ return {};
+
+ if (structsize == 0)
+ return buf;
+
+ gdb::byte_vector desc (sizeof (structsize) + buf->size ());
+ memcpy (desc.data (), &structsize, sizeof (structsize));
+ memcpy (desc.data () + sizeof (structsize), buf->data (), buf->size ());
+ return desc;
+}
+
/* Create appropriate note sections for a corefile, returning them in
allocated memory. */

@@ -586,6 +603,43 @@ fbsd_make_corefile_notes (struct gdbarch *gdbarch, bfd *obfd, int *note_size)

note_data = thread_args.note_data;

+ pid_t pid = inferior_ptid.pid ();
+
+ /* Auxiliary vector. */
+ uint32_t structsize = gdbarch_ptr_bit (gdbarch) / 4; /* Elf_Auxinfo */
+ gdb::optional<gdb::byte_vector> note_desc =
+ fbsd_make_note_desc (TARGET_OBJECT_AUXV, structsize);
+ if (note_desc && !note_desc->empty ())
+ {
+ note_data = elfcore_write_note (obfd, note_data, note_size,
+ "FreeBSD", NT_FREEBSD_PROCSTAT_AUXV,
+ note_desc->data (), note_desc->size ());
+ if (!note_data)
+ return NULL;
+ }
+
+ /* Virtual memory mappings */
+ note_desc = fbsd_make_note_desc (TARGET_OBJECT_FREEBSD_VMMAP, 0);
+ if (note_desc && !note_desc->empty ())
+ {
+ note_data = elfcore_write_note (obfd, note_data, note_size,
+ "FreeBSD", NT_FREEBSD_PROCSTAT_VMMAP,
+ note_desc->data (), note_desc->size ());
+ if (!note_data)
+ return NULL;
+ }
+
+ note_desc =
+ fbsd_make_note_desc (TARGET_OBJECT_FREEBSD_PS_STRINGS, 0);
+ if (note_desc && !note_desc->empty ())
+ {
+ note_data = elfcore_write_note (obfd, note_data, note_size, "FreeBSD",
+ NT_FREEBSD_PROCSTAT_PSSTRINGS,
+ note_desc->data (), note_desc->size ());
+ if (!note_data)
+ return NULL;
+ }
+
return note_data;
}

diff --git a/gdb/target.h b/gdb/target.h
index 18c4a84c..c584af54 100644
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -203,6 +203,10 @@ enum target_object
of the process ID of the process in question, in hexadecimal
format. */
TARGET_OBJECT_EXEC_FILE,
+ /* FreeBSD virtual memory mappings */
+ TARGET_OBJECT_FREEBSD_VMMAP,
+ /* FreeBSD process strings */
+ TARGET_OBJECT_FREEBSD_PS_STRINGS,
/* Possible future objects: TARGET_OBJECT_FILE, ... */
};

--
2.18.0