Use gdbarch_long_bit to determine layout of FreeBSD siginfo_t.

  FreeBSD architectures are either ILP32 or LP64 resulting in two
different layouts for siginfo_t.  Previously, the 'bits_per_word'
member of bfd_arch_info was used to determine the layout to use for a
given FreeBSD architecture.  However, mipsn32 architectures inherit
from a 64-bit mips architecture where bits_per_word is 64.  As a
result, $_siginfo was not properly extracted from FreeBSD/mipsn32 core
dumps.  Fix this by using gdbarch_long_bit instead of 'bits_per_word'
to determine if a FreeBSD architecture is ILP32 or LP64.

gdb/ChangeLog:

	* fbsd-nat.c (fbsd_siginfo_size): Use gdbarch_long_bit.
	(fbsd_convert_siginfo): Likewise.
	* fbsd-tdep.c (fbsd_core_xfer_siginfo): Likewise.
---
 gdb/ChangeLog   | 6 ++++++
 gdb/fbsd-nat.c  | 4 ++--
 gdb/fbsd-tdep.c | 4 ++--
 3 files changed, 10 insertions(+), 4 deletions(-)
  

On 2017-10-06 06:48 PM, John Baldwin wrote:
> FreeBSD architectures are either ILP32 or LP64 resulting in two
> different layouts for siginfo_t.  Previously, the 'bits_per_word'
> member of bfd_arch_info was used to determine the layout to use for a
> given FreeBSD architecture.  However, mipsn32 architectures inherit
> from a 64-bit mips architecture where bits_per_word is 64.  As a
> result, $_siginfo was not properly extracted from FreeBSD/mipsn32 core
> dumps.  Fix this by using gdbarch_long_bit instead of 'bits_per_word'
> to determine if a FreeBSD architecture is ILP32 or LP64.
> 
> gdb/ChangeLog:
> 
> 	* fbsd-nat.c (fbsd_siginfo_size): Use gdbarch_long_bit.
> 	(fbsd_convert_siginfo): Likewise.
> 	* fbsd-tdep.c (fbsd_core_xfer_siginfo): Likewise.
> ---
>  gdb/ChangeLog   | 6 ++++++
>  gdb/fbsd-nat.c  | 4 ++--
>  gdb/fbsd-tdep.c | 4 ++--
>  3 files changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/gdb/ChangeLog b/gdb/ChangeLog
> index 18224e0305..f72c47302e 100644
> --- a/gdb/ChangeLog
> +++ b/gdb/ChangeLog
> @@ -1,3 +1,9 @@
> +2017-10-06  John Baldwin  <jhb@FreeBSD.org>
> +
> +	* fbsd-nat.c (fbsd_siginfo_size): Use gdbarch_long_bit.
> +	(fbsd_convert_siginfo): Likewise.
> +	* fbsd-tdep.c (fbsd_core_xfer_siginfo): Likewise.
> +
>  2017-10-06  Yao Qi  <yao.qi@linaro.org>
>  
>  	* Makefile.in (ALL_64_TARGET_OBS): Replace aarch64-insn.o with
> diff --git a/gdb/fbsd-nat.c b/gdb/fbsd-nat.c
> index 5ad0dda5b4..265175a769 100644
> --- a/gdb/fbsd-nat.c
> +++ b/gdb/fbsd-nat.c
> @@ -279,7 +279,7 @@ fbsd_siginfo_size ()
>    struct gdbarch *gdbarch = get_frame_arch (get_current_frame ());
>  
>    /* Is the inferior 32-bit?  If so, use the 32-bit siginfo size.  */
> -  if (gdbarch_bfd_arch_info (gdbarch)->bits_per_word == 32)
> +  if (gdbarch_long_bit (gdbarch) == 32)
>      return sizeof (struct siginfo32);
>  #endif
>    return sizeof (siginfo_t);
> @@ -296,7 +296,7 @@ fbsd_convert_siginfo (siginfo_t *si)
>    struct gdbarch *gdbarch = get_frame_arch (get_current_frame ());
>  
>    /* Is the inferior 32-bit?  If not, nothing to do.  */
> -  if (gdbarch_bfd_arch_info (gdbarch)->bits_per_word != 32)
> +  if (gdbarch_long_bit (gdbarch) != 32)
>      return;
>  
>    struct siginfo32 si32;
> diff --git a/gdb/fbsd-tdep.c b/gdb/fbsd-tdep.c
> index fa4cd912ef..fa70f7c20b 100644
> --- a/gdb/fbsd-tdep.c
> +++ b/gdb/fbsd-tdep.c
> @@ -143,7 +143,7 @@ fbsd_core_xfer_siginfo (struct gdbarch *gdbarch, gdb_byte *readbuf,
>  {
>    size_t siginfo_size;
>  
> -  if (gdbarch_bfd_arch_info (gdbarch)->bits_per_word == 32)
> +  if (gdbarch_long_bit (gdbarch) == 32)
>      siginfo_size = SIZE32_SIGINFO_T;
>    else
>      siginfo_size = SIZE64_SIGINFO_T;
> @@ -168,7 +168,7 @@ fbsd_core_xfer_siginfo (struct gdbarch *gdbarch, gdb_byte *readbuf,
>      len = siginfo_size - offset;
>  
>    ULONGEST siginfo_offset;
> -  if (gdbarch_bfd_arch_info (gdbarch)->bits_per_word == 32)
> +  if (gdbarch_long_bit (gdbarch) == 32)
>      siginfo_offset = LWPINFO_OFFSET + LWPINFO32_PL_SIGINFO;
>    else
>      siginfo_offset = LWPINFO_OFFSET + LWPINFO64_PL_SIGINFO;
> 

That looks reasonnable to me.

Simon