This is the mail archive of the gdb-patches@sourceware.org mailing list for the GDB project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

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



> On 6 Aug 2018, at 19:29, Simon Marchi <simon.marchi@ericsson.com> wrote:
> 
> 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.
> 

Yes! I’ll consider adding the function too.

>> +
>> +  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?
> 

No. The supply_regset directly afterwards will write to the V registers.
With SVE, the V registers are pseudo registers built off the Z registers.
I do the clear to ensure the non overlapping parts of the Z registers are cleared.




Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]