Dave Martin <Dave.Martin@xxxxxxx> writes: > This patch defines the representation that will be used for the SVE > register state in the signal frame, and implements support for > saving and restoring the SVE registers around signals. > > The same layout will also be used for the in-kernel task state. > > Due to the variability of the SVE vector length, it is not possible > to define a fixed C struct to describe all the registers. Instead, > Macros are defined in sigcontext.h to facilitate access to the > parts of the structure. > > Signed-off-by: Dave Martin <Dave.Martin@xxxxxxx> > --- > arch/arm64/include/uapi/asm/sigcontext.h | 113 ++++++++++++++++++++++++++++++- > 1 file changed, 112 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/include/uapi/asm/sigcontext.h b/arch/arm64/include/uapi/asm/sigcontext.h > index f0a76b9..0533bdf 100644 > --- a/arch/arm64/include/uapi/asm/sigcontext.h > +++ b/arch/arm64/include/uapi/asm/sigcontext.h > @@ -16,6 +16,8 @@ > #ifndef _UAPI__ASM_SIGCONTEXT_H > #define _UAPI__ASM_SIGCONTEXT_H > > +#ifndef __ASSEMBLY__ > + > #include <linux/types.h> > > /* > @@ -41,10 +43,11 @@ struct sigcontext { > * > * 0x210 fpsimd_context > * 0x10 esr_context > + * 0x8a0 sve_context (vl <= 64) (optional) > * 0x20 extra_context (optional) > * 0x10 terminator (null _aarch64_ctx) > * > - * 0xdb0 (reserved for future allocation) > + * 0x510 (reserved for future allocation) > * > * New records that can exceed this space need to be opt-in for userspace, so > * that an expanded signal frame is not generated unexpectedly. The mechanism > @@ -116,4 +119,112 @@ struct extra_context { > __u32 __reserved[3]; > }; > > +#define SVE_MAGIC 0x53564501 > + > +struct sve_context { > + struct _aarch64_ctx head; > + __u16 vl; > + __u16 __reserved[3]; > +}; > + > +#endif /* !__ASSEMBLY__ */ > + > +/* > + * The SVE architecture leaves space for future expansion of the > + * vector length beyond its initial architectural limit of 2048 bits > + * (16 quadwords). > + */ > +#define SVE_VQ_MIN 1 > +#define SVE_VQ_MAX 0x200 > + > +#define SVE_VL_MIN (SVE_VQ_MIN * 0x10) > +#define SVE_VL_MAX (SVE_VQ_MAX * 0x10) > + > +#define SVE_NUM_ZREGS 32 > +#define SVE_NUM_PREGS 16 > + > +#define sve_vl_valid(vl) \ > + ((vl) % 0x10 == 0 && (vl) >= SVE_VL_MIN && (vl) <= SVE_VL_MAX) > +#define sve_vq_from_vl(vl) ((vl) / 0x10) > +#define sve_vl_from_vq(vq) ((vq) * 0x10) I got a little confused first time through over what VQ and VL where. Maybe it would make sense to expand a little more from first principles? /* * The SVE architecture defines vector registers as a multiple of 128 * bit quadwords. The current architectural limit is 2048 bits (16 * quadwords) but there is room for future expansion beyond that. */ #define SVE_VQ_BITS 128 /* 128 bits in one quadword */ #define SVE_VQ_BYTES (SVE_VQ_BITS / 8) #define SVE_VQ_MIN 1 #define SVE_VQ_MAX 0x200 /* see ZCR_ELx[8:0] */ #define SVE_VL_MIN_BYTES (SVE_VQ_MIN * SVE_VQ_BYTES) #define SVE_VL_MAX_BYTES (SVE_VQ_MAX * SVE_VQ_BYTES) #define SVE_NUM_ZREGS 32 #define SVE_NUM_PREGS 16 #define sve_vl_valid(vl) \ ((vl) % SVE_VQ_BYTES == 0 && (vl) >= SVE_VL_MIN && (vl) <= SVE_VL_MAX) #define sve_vq_from_vl(vl) ((vl) / SVE_VQ_BYTES) #define sve_vl_from_vq(vq) ((vq) * SVE_VQ_BYTES) > + > +/* > + * If the SVE registers are currently live for the thread at signal delivery, > + * sve_context.head.size >= > + * SVE_SIG_CONTEXT_SIZE(sve_vq_from_vl(sve_context.vl)) > + * and the register data may be accessed using the SVE_SIG_*() macros. > + * > + * If sve_context.head.size < > + * SVE_SIG_CONTEXT_SIZE(sve_vq_from_vl(sve_context.vl)), > + * the SVE registers were not live for the thread and no register data > + * is included: in this case, the SVE_SIG_*() macros should not be > + * used except for this check. > + * > + * The same convention applies when returning from a signal: a caller > + * will need to remove or resize the sve_context block if it wants to > + * make the SVE registers live when they were previously non-live or > + * vice-versa. This may require the the caller to allocate fresh > + * memory and/or move other context blocks in the signal frame. > + * > + * Changing the vector length during signal return is not permitted: > + * sve_context.vl must equal the thread's current vector length when > + * doing a sigreturn. > + * > + * > + * Note: for all these macros, the "vq" argument denotes the SVE > + * vector length in quadwords (i.e., units of 128 bits). > + * > + * The correct way to obtain vq is to use sve_vq_from_vl(vl). The > + * result is valid if and only if sve_vl_valid(vl) is true. This is > + * guaranteed for a struct sve_context written by the kernel. > + * > + * > + * Additional macros describe the contents and layout of the payload. > + * For each, SVE_SIG_x_OFFSET(args) is the start offset relative to > + * the start of struct sve_context, and SVE_SIG_x_SIZE(args) is the > + * size in bytes: > + * > + * x type description > + * - ---- ----------- > + * REGS the entire SVE context > + * > + * ZREGS __uint128_t[SVE_NUM_ZREGS][vq] all Z-registers > + * ZREG __uint128_t[vq] individual Z-register Zn > + * > + * PREGS uint16_t[SVE_NUM_PREGS][vq] all P-registers > + * PREG uint16_t[vq] individual P-register Pn > + * > + * FFR uint16_t[vq] first-fault status register > + * > + * Additional data might be appended in the future. > + */ > + > +#define SVE_SIG_ZREG_SIZE(vq) ((__u32)(vq) * 16) > +#define SVE_SIG_PREG_SIZE(vq) ((__u32)(vq) * 2) > +#define SVE_SIG_FFR_SIZE(vq) SVE_SIG_PREG_SIZE(vq) > + > +#define SVE_SIG_REGS_OFFSET ((sizeof(struct sve_context) + 15) / 16 * 16) > + > +#define SVE_SIG_ZREGS_OFFSET SVE_SIG_REGS_OFFSET > +#define SVE_SIG_ZREG_OFFSET(vq, n) \ > + (SVE_SIG_ZREGS_OFFSET + SVE_SIG_ZREG_SIZE(vq) * (n)) > +#define SVE_SIG_ZREGS_SIZE(vq) \ > + (SVE_SIG_ZREG_OFFSET(vq, SVE_NUM_ZREGS) - SVE_SIG_ZREGS_OFFSET) > + > +#define SVE_SIG_PREGS_OFFSET(vq) \ > + (SVE_SIG_ZREGS_OFFSET + SVE_SIG_ZREGS_SIZE(vq)) > +#define SVE_SIG_PREG_OFFSET(vq, n) \ > + (SVE_SIG_PREGS_OFFSET(vq) + SVE_SIG_PREG_SIZE(vq) * (n)) > +#define SVE_SIG_PREGS_SIZE(vq) \ > + (SVE_SIG_PREG_OFFSET(vq, SVE_NUM_PREGS) - SVE_SIG_PREGS_OFFSET(vq)) > + > +#define SVE_SIG_FFR_OFFSET(vq) \ > + (SVE_SIG_PREGS_OFFSET(vq) + SVE_SIG_PREGS_SIZE(vq)) > + > +#define SVE_SIG_REGS_SIZE(vq) \ > + (SVE_SIG_FFR_OFFSET(vq) + SVE_SIG_FFR_SIZE(vq) - SVE_SIG_REGS_OFFSET) > + > +#define SVE_SIG_CONTEXT_SIZE(vq) (SVE_SIG_REGS_OFFSET + SVE_SIG_REGS_SIZE(vq)) > + > + > #endif /* _UAPI__ASM_SIGCONTEXT_H */ -- Alex Bennée