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

Simon Ser
2018-09-02T20:02:08Z

Hi John,

Did you have time to have a look at this new version ?

Thanks,
---
Simon Ser
https://emersion.fr

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On 23 August 2018 7:10 PM, Simon Ser <contact@emersion.fr> wrote:

> 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::optionalgdb::byte_vector
> +fbsd_make_note_desc (enum target_object object, uint32_t structsize)
> +{
>
> - gdb::optionalgdb::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::optionalgdb::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
>