Add support for reading and writing registers for Aarch64 SVE.
We need to support the cases where the kernel only gives us a
fpsimd structure. This occurs when there is no active SVE state
in the kernel (for example, after starting a new process).
Added checks to make sure the vector length has not changed whilst
the process is running.
gdb/
* aarch64-linux-nat.c (fetch_sveregs_from_thread): New function.
(store_sveregs_to_thread): Likewise.
(aarch64_linux_fetch_inferior_registers): Check for SVE.
(aarch64_linux_store_inferior_registers): Likewise.
* nat/aarch64-sve-linux-ptrace.c (aarch64_sve_get_sveregs): New
function.
(aarch64_sve_regs_copy_to_regcache): Likewise.
(aarch64_sve_regs_copy_from_regcache): Likewise.
* nat/aarch64-sve-linux-ptrace.h (aarch64_sve_get_sveregs): New
declaration.
(aarch64_sve_regs_copy_to_regcache): Likewise.
(aarch64_sve_regs_copy_from_regcache): Likewise.
(sve_context): Structure from Linux headers.
(SVE_SIG_ZREGS_SIZE): Define from Linux headers.
(SVE_SIG_ZREG_SIZE): Likewise.
(SVE_SIG_PREG_SIZE): Likewise.
(SVE_SIG_FFR_SIZE): Likewise.
(SVE_SIG_REGS_OFFSET): Likewise.
(SVE_SIG_ZREGS_OFFSET): Likewise.
(SVE_SIG_ZREG_OFFSET): Likewise.
(SVE_SIG_ZREGS_SIZE): Likewise.
(SVE_SIG_PREGS_OFFSET): Likewise.
(SVE_SIG_PREG_OFFSET): Likewise.
(SVE_SIG_PREGS_SIZE): Likewise.
(SVE_SIG_FFR_OFFSET): Likewise.
(SVE_SIG_REGS_SIZE): Likewise.
(SVE_SIG_CONTEXT_SIZE): Likewise.
(SVE_PT_REGS_MASK): Likewise.
(SVE_PT_REGS_FPSIMD): Likewise.
(SVE_PT_REGS_SVE): Likewise.
(SVE_PT_VL_INHERIT): Likewise.
(SVE_PT_VL_ONEXEC): Likewise.
(SVE_PT_REGS_OFFSET): Likewise.
(SVE_PT_FPSIMD_OFFSET): Likewise.
(SVE_PT_FPSIMD_SIZE): Likewise.
(SVE_PT_SVE_ZREG_SIZE): Likewise.
(SVE_PT_SVE_PREG_SIZE): Likewise.
(SVE_PT_SVE_FFR_SIZE): Likewise.
(SVE_PT_SVE_FPSR_SIZE): Likewise.
(SVE_PT_SVE_FPCR_SIZE): Likewise.
(__SVE_SIG_TO_PT): Likewise.
(SVE_PT_SVE_OFFSET): Likewise.
(SVE_PT_SVE_ZREGS_OFFSET): Likewise.
(SVE_PT_SVE_ZREG_OFFSET): Likewise.
(SVE_PT_SVE_ZREGS_SIZE): Likewise.
(SVE_PT_SVE_PREGS_OFFSET): Likewise.
(SVE_PT_SVE_PREG_OFFSET): Likewise.
(SVE_PT_SVE_PREGS_SIZE): Likewise.
(SVE_PT_SVE_FFR_OFFSET): Likewise.
(SVE_PT_SVE_FPSR_OFFSET): Likewise.
(SVE_PT_SVE_FPCR_OFFSET): Likewise.
(SVE_PT_SVE_SIZE): Likewise.
(SVE_PT_SIZE): Likewise.
(HAS_SVE_STATE): New define.
gdbserver/
* Makefile.in: Add aarch64-sve-linux-ptrace.c.
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