Re: [PATCH v2 3/3] Parse SVE registers in aarch64 core file reading/writing

[Simon Marchi <simon dot marchi at ericsson dot com>]

On 2018-07-30 05:25 AM, Alan Hayward wrote:
> sve_regmap cannot be global static as the size is dependant on the current
> vector length.
> 
> 2018-07-30  Alan Hayward  <alan.hayward@arm.com>
> 
> 	* aarch64-linux-tdep.c (aarch64_linux_supply_sve_regset): New function.
> 	(aarch64_linux_collect_sve_regset): Likewise.
> 	(aarch64_linux_iterate_over_regset_sections): Check for SVE.
> 	* regcache.h (regcache_map_entry_size): New function.
> ---
>  gdb/aarch64-linux-tdep.c | 112 ++++++++++++++++++++++++++++++++++++++++++++++-
>  gdb/regcache.h           |   8 ++++
>  2 files changed, 118 insertions(+), 2 deletions(-)
> 
> diff --git a/gdb/aarch64-linux-tdep.c b/gdb/aarch64-linux-tdep.c
> index f9a95950da..bd61a2d722 100644
> --- a/gdb/aarch64-linux-tdep.c
> +++ b/gdb/aarch64-linux-tdep.c
> @@ -288,6 +288,85 @@ aarch64_linux_core_read_vq (struct gdbarch *gdbarch, bfd *abfd)
>    return vq;
>  }
>  
> +/* Supply register REGNUM from BUF to REGCACHE, using the register map
> +   in REGSET.  If REGNUM is -1, do this for all registers in REGSET.
> +   If BUF is NULL, set the registers to "unavailable" status.  */
> +
> +static void
> +aarch64_linux_supply_sve_regset (const struct regset *regset,
> +				 struct regcache *regcache,
> +				 int regnum, const void *buf, size_t size)
> +{
> +  struct gdbarch *gdbarch = regcache->arch ();
> +  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
> +
> +  if (buf == nullptr)
> +    return regcache->supply_regset (regset, regnum, nullptr, size);
> +  gdb_assert (size > SVE_HEADER_SIZE);
> +
> +  /* BUF contains an SVE header followed by a register dump of either the
> +     passed in SVE regset or a NEON fpregset.  */
> +
> +  /* Extract required fields from the header.  */
> +  uint64_t vg = sve_vg_from_vl (SVE_HEADER_READ (buf, 2, byte_order));
> +  uint16_t flags = SVE_HEADER_READ (buf, 4, byte_order);
> +
> +  if (regnum == -1 || regnum == AARCH64_SVE_VG_REGNUM)
> +    regcache->raw_supply (AARCH64_SVE_VG_REGNUM, &vg);

I think this raw_supply is wrong.  The vg local variable is in host byte order,
but the data in the buffer passed to raw_supply should be in target.  So you
may need to do a store_unsigned_integer in a buffer and supply that.  If this
is a pattern that happens often enough, maybe it would be worth having a
raw_supply that does this conversion from integer to register buffer, a bit
like "regcache::raw_write (int regnum, T val)" does.

> +
> +  if (flags & 1)
> +    {
> +      /* Register dump is a SVE structure.  */
> +      regcache->supply_regset (regset, regnum,
> +			       (gdb_byte *) buf + SVE_HEADER_SIZE,
> +			       size - SVE_HEADER_SIZE);
> +    }
> +  else
> +    {
> +      /* Register dump is a fpsimd structure.  First clear the SVE
> +	 registers.  */
> +      for (int i = 0; i < AARCH64_SVE_Z_REGS_NUM; i++)
> +	regcache->raw_supply_zeroed (AARCH64_SVE_Z0_REGNUM + i);
> +      for (int i = 0; i < AARCH64_SVE_P_REGS_NUM; i++)
> +	regcache->raw_supply_zeroed (AARCH64_SVE_P0_REGNUM + i);
> +      regcache->raw_supply_zeroed (AARCH64_SVE_FFR_REGNUM);

Just wondering, should they be made unavailable instead of cleared?

Simon