target/arm: Added support for SME register exposure to GDB

The QEMU GDB stub does not expose the ZA storage SME register to GDB
via the remote serial protocol, which can be a useful functionality
to debug SME code.  To provide this functionality for AArch64
targets, this patch registers the SME register set with the GDB stub.
To do so, this patch implements the aarch64_gdb_get_sme_reg() and
aarch64_gdb_set_sme_reg() functions to specify how to get and set the
SME registers, and the arm_gen_dynamic_smereg_feature() function to
generate the target description in XML format to indicate the target
architecture supports SME.  Finally, this patch includes a
dyn_smereg_feature structure to hold this GDB XML description of the
SME registers for each CPU.

Note that according to the GDB documentation the ZA register is
defined as a vector of bytes; however the target description xml
retrieved when using gdb natively on a host with SME capabilities
represents the ZA register as a vector of vectors of bytes, so this
is a GDB documentation error.  We follow GDB's own gdbstub
implementation and represent the ZA register as a vector of vectors
of bytes as is done by GDB here:

https://github.com/bminor/binutils-gdb/blob/5cce2b7006daa7073b98e3d1a3b176199d1381d7/gdb/features/aarch64-sme.c#L50

Signed-off-by: Vacha Bhavsar <vacha.bhavsar@oss.qualcomm.com>
Message-id: 20250909161012.2561593-3-vacha.bhavsar@oss.qualcomm.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
[PMM: fixed minor checkpatch nits]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

0 files changed, 0 insertions, 0 deletions