On Fri, Oct 27, 2017 at 11:51:01AM +0100, Dave P Martin wrote: > This patch defines and implements a new regset NT_ARM_SVE, which > describes a thread's SVE register state. This allows a debugger to > manipulate the SVE state, as well as being included in ELF > coredumps for post-mortem debugging. > > Because the regset size and layout are dependent on the thread's > current vector length, it is not possible to define a C struct to > describe the regset contents as is done for existing regsets. > Instead, and for the same reasons, NT_ARM_SVE is based on the > freeform variable-layout approach used for the SVE signal frame. > > Additionally, to reduce debug overhead when debugging threads that > might or might not have live SVE register state, NT_ARM_SVE may be > presented in one of two different formats: the old struct > user_fpsimd_state format is embedded for describing the state of a > thread with no live SVE state, whereas a new variable-layout > structure is embedded for describing live SVE state. This avoids a > debugger needing to poll NT_PRFPREG in addition to NT_ARM_SVE, and > allows existing userspace code to handle the non-SVE case without > too much modification. > > For this to work, NT_ARM_SVE is defined with a fixed-format header > of type struct user_sve_header, which the recipient can use to > figure out the content, size and layout of the reset of the regset. > Accessor macros are defined to allow the vector-length-dependent > parts of the regset to be manipulated. > > Signed-off-by: Alan Hayward <alan.hayward@xxxxxxx> > Signed-off-by: Dave Martin <Dave.Martin@xxxxxxx> > Cc: Alex Bennée <alex.bennee@xxxxxxxxxx> > Cc: Okamoto Takayuki <tokamoto@xxxxxxxxxxxxxx> Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
