Re: [PATCH v3 09/13] riscv: vector: Support xtheadvector save/restore

Hi Charlie,

A couple of suggestions for simplification below.

On 2024-06-19 6:57 PM, Charlie Jenkins wrote:

Use alternatives to add support for xtheadvector vector save/restore routines.

Signed-off-by: Charlie Jenkins charlie@rivosinc.com Reviewed-by: Conor Dooley conor.dooley@microchip.com

---

arch/riscv/include/asm/csr.h | 6 + arch/riscv/include/asm/switch_to.h | 2 +- arch/riscv/include/asm/vector.h | 249 ++++++++++++++++++++++++++------- arch/riscv/kernel/cpufeature.c | 2 +- arch/riscv/kernel/kernel_mode_vector.c | 8 +- arch/riscv/kernel/process.c | 4 +- arch/riscv/kernel/signal.c | 6 +- arch/riscv/kernel/vector.c | 13 +- 8 files changed, 222 insertions(+), 68 deletions(-)

diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h index 9086639a3dde..407d4a5687f5 100644 --- a/arch/riscv/include/asm/csr.h +++ b/arch/riscv/include/asm/csr.h @@ -30,6 +30,12 @@ #define SR_VS_CLEAN _AC(0x00000400, UL) #define SR_VS_DIRTY _AC(0x00000600, UL) +#define SR_VS_THEAD _AC(0x01800000, UL) /* xtheadvector Status */ +#define SR_VS_OFF_THEAD _AC(0x00000000, UL) +#define SR_VS_INITIAL_THEAD _AC(0x00800000, UL) +#define SR_VS_CLEAN_THEAD _AC(0x01000000, UL) +#define SR_VS_DIRTY_THEAD _AC(0x01800000, UL)

#define SR_XS _AC(0x00018000, UL) /* Extension Status */ #define SR_XS_OFF _AC(0x00000000, UL) #define SR_XS_INITIAL _AC(0x00008000, UL) diff --git a/arch/riscv/include/asm/switch_to.h b/arch/riscv/include/asm/switch_to.h index 7594df37cc9f..f9cbebe372b8 100644 --- a/arch/riscv/include/asm/switch_to.h +++ b/arch/riscv/include/asm/switch_to.h @@ -99,7 +99,7 @@ do { \ __set_prev_cpu(__prev->thread); \ if (has_fpu()) \ __switch_to_fpu(__prev, __next); \

• if (has_vector()) \

• if (has_vector() || has_xtheadvector()) \ __switch_to_vector(__prev, __next); \ if (switch_to_should_flush_icache(__next)) \ local_flush_icache_all(); \

diff --git a/arch/riscv/include/asm/vector.h b/arch/riscv/include/asm/vector.h index 731dcd0ed4de..6294dcaabc6a 100644 --- a/arch/riscv/include/asm/vector.h +++ b/arch/riscv/include/asm/vector.h @@ -18,6 +18,27 @@ #include <asm/cpufeature.h> #include <asm/csr.h> #include <asm/asm.h> +#include <asm/vendorid_list.h> +#include <asm/vendor_extensions.h> +#include <asm/vendor_extensions/thead.h>

+#define __riscv_v_vstate_or(_val, TYPE) ({ \

• typeof(_val) _res = _val; \
• if (has_xtheadvector()) \

• _res = (_res & ~SR_VS_THEAD) | SR_VS_##TYPE##_THEAD;	\
  

• else \

• _res = (_res & ~SR_VS) | SR_VS_##TYPE;			\
  

• _res; \

+})

+#define __riscv_v_vstate_check(_val, TYPE) ({ \

• bool _res; \
• if (has_xtheadvector()) \

• _res = ((_val) & SR_VS_THEAD) == SR_VS_##TYPE##_THEAD;	\
  

• else \

• _res = ((_val) & SR_VS) == SR_VS_##TYPE;		\
  

• _res; \

+}) extern unsigned long riscv_v_vsize; int riscv_v_setup_vsize(void); @@ -40,39 +61,62 @@ static __always_inline bool has_vector(void) return riscv_has_extension_unlikely(RISCV_ISA_EXT_v); } +static __always_inline bool has_xtheadvector_no_alternatives(void) +{

• if (IS_ENABLED(CONFIG_RISCV_ISA_XTHEADVECTOR))

• return riscv_isa_vendor_extension_available(THEAD_VENDOR_ID, XTHEADVECTOR);
  

• else

• return false;
  

+}

+static __always_inline bool has_xtheadvector(void) +{

• if (IS_ENABLED(CONFIG_RISCV_ISA_XTHEADVECTOR))

• return riscv_has_vendor_extension_unlikely(THEAD_VENDOR_ID,
  

• 					   RISCV_ISA_VENDOR_EXT_XTHEADVECTOR);
  

• else

• return false;
  

+}

static inline void __riscv_v_vstate_clean(struct pt_regs *regs) {

• regs->status = (regs->status & ~SR_VS) | SR_VS_CLEAN;

• regs->status = __riscv_v_vstate_or(regs->status, CLEAN);

} static inline void __riscv_v_vstate_dirty(struct pt_regs *regs) {

• regs->status = (regs->status & ~SR_VS) | SR_VS_DIRTY;

• regs->status = __riscv_v_vstate_or(regs->status, DIRTY);

} static inline void riscv_v_vstate_off(struct pt_regs *regs) {

• regs->status = (regs->status & ~SR_VS) | SR_VS_OFF;

• regs->status = __riscv_v_vstate_or(regs->status, OFF);

} static inline void riscv_v_vstate_on(struct pt_regs *regs) {

• regs->status = (regs->status & ~SR_VS) | SR_VS_INITIAL;

• regs->status = __riscv_v_vstate_or(regs->status, INITIAL);

} static inline bool riscv_v_vstate_query(struct pt_regs *regs) {

• return (regs->status & SR_VS) != 0;

• return !__riscv_v_vstate_check(regs->status, OFF);

} static __always_inline void riscv_v_enable(void) {

• csr_set(CSR_SSTATUS, SR_VS);

• if (has_xtheadvector())

• csr_set(CSR_SSTATUS, SR_VS_THEAD);
  

• else

• csr_set(CSR_SSTATUS, SR_VS);
  

} static __always_inline void riscv_v_disable(void) {

• csr_clear(CSR_SSTATUS, SR_VS);

• if (has_xtheadvector())

• csr_clear(CSR_SSTATUS, SR_VS_THEAD);
  

• else

• csr_clear(CSR_SSTATUS, SR_VS);
  

} static __always_inline void __vstate_csr_save(struct __riscv_v_ext_state *dest) @@ -81,10 +125,49 @@ static __always_inline void __vstate_csr_save(struct __riscv_v_ext_state *dest) "csrr %0, " __stringify(CSR_VSTART) "\n\t" "csrr %1, " __stringify(CSR_VTYPE) "\n\t" "csrr %2, " __stringify(CSR_VL) "\n\t"

• "csrr	%3, " __stringify(CSR_VCSR) "\n\t"
  

• "csrr	%4, " __stringify(CSR_VLENB) "\n\t"
  

  : "=r" (dest->vstart), "=r" (dest->vtype), "=r" (dest->vl),

•   "=r" (dest->vcsr), "=r" (dest->vlenb) : :);
  

• "=r" (dest->vcsr) : :);
  

• if (has_xtheadvector()) {

• u32 tmp_vcsr;
  

• bool restore_fpu = false;
  

• unsigned long status = csr_read(CSR_SSTATUS);
  

• /*
  

•  * CSR_VCSR is defined as
  

•  * [2:1] - vxrm[1:0]
  

•  * [0] - vxsat
  

•  * The earlier vector spec implemented by T-Head uses separate
  

•  * registers for the same bit-elements, so just combine those
  

•  * into the existing output field.
  

•  *
  

•  * Additionally T-Head cores need FS to be enabled when accessing
  

•  * the VXRM and VXSAT CSRs, otherwise ending in illegal instructions.
  

•  * Though the cores do not implement the VXRM and VXSAT fields in the
  

•  * FCSR CSR that vector-0.7.1 specifies.
  

•  */
  

• if ((status & SR_FS) == SR_FS_OFF) {
  

• 	csr_set(CSR_SSTATUS, (status & ~SR_FS) | SR_FS_CLEAN);
  

• 	restore_fpu = true;
  

• }
  

This simplifies to:

unsigned long status = csr_read_set(CSR_STATUS, SR_FS_DIRTY);

and then below:

if ((status & SR_FS) != SR_FS_DIRTY) csr_write(CSR_STATUS, status);

• asm volatile (
  

• 	"csrr	%[tmp_vcsr], " __stringify(VCSR_VXRM) "\n\t"
  

• 	"slliw	%[vcsr], %[tmp_vcsr], " __stringify(VCSR_VXRM_SHIFT) "\n\t"
  

• 	"csrr	%[tmp_vcsr], " __stringify(VCSR_VXSAT) "\n\t"
  

• 	"or	%[vcsr], %[vcsr], %[tmp_vcsr]\n\t"
  

• 	: [vcsr] "=r" (dest->vcsr), [tmp_vcsr] "=&r" (tmp_vcsr));
  

None of this needs to be inline assembly. I think the only reason that __vstate_csr_save() uses inline assembly is to match __vstate_csr_restore(), which needs it to execute a vsetvl instruction. This would be easier to parse if it used csr_read().

• dest->vlenb = riscv_v_vsize / 32;
  

This value can't change at runtime (for either standard V or Xtheadvector), so we don't need to save it every time. So (possibly as a future optimization) this could be saved only once when the context is first initialized.

• if (restore_fpu)
  

• 	csr_set(CSR_SSTATUS, status);
  

• } else {

• asm volatile (
  

• 	"csrr	%[vcsr], " __stringify(CSR_VCSR) "\n\t"
  

• 	"csrr	%[vlenb], " __stringify(CSR_VLENB) "\n\t"
  

• 	: [vcsr] "=r" (dest->vcsr), [vlenb] "=r" (dest->vlenb));
  

• }

} static __always_inline void __vstate_csr_restore(struct __riscv_v_ext_state *src) @@ -95,9 +178,37 @@ static __always_inline void __vstate_csr_restore(struct __riscv_v_ext_state *src "vsetvl x0, %2, %1\n\t" ".option pop\n\t" "csrw " __stringify(CSR_VSTART) ", %0\n\t"

• "csrw	" __stringify(CSR_VCSR) ", %3\n\t"
  

• : : "r" (src->vstart), "r" (src->vtype), "r" (src->vl),
  

•     "r" (src->vcsr) :);
  

• : : "r" (src->vstart), "r" (src->vtype), "r" (src->vl));
  

• if (has_xtheadvector()) {

• u32 tmp_vcsr;
  

• bool restore_fpu = false;
  

• unsigned long status = csr_read(CSR_SSTATUS);
  

• /*
  

•  * Similar to __vstate_csr_save above, restore values for the
  

•  * separate VXRM and VXSAT CSRs from the vcsr variable.
  

•  */
  

• if ((status & SR_FS) == SR_FS_OFF) {
  

• 	csr_set(CSR_SSTATUS, (status & ~SR_FS) | SR_FS_CLEAN);
  

• 	restore_fpu = true;
  

• }
  

• asm volatile (
  

• 	"srliw	%[tmp_vcsr], %[vcsr], " __stringify(VCSR_VXRM_SHIFT) "\n\t"
  

• 	"andi	%[tmp_vcsr], %[tmp_vcsr], " __stringify(VCSR_VXRM_MASK) "\n\t"
  

• 	"csrw	" __stringify(VCSR_VXRM) ", %[tmp_vcsr]\n\t"
  

• 	"andi	%[tmp_vcsr], %[vcsr], " __stringify(VCSR_VXSAT_MASK) "\n\t"
  

• 	"csrw	" __stringify(VCSR_VXSAT) ", %[tmp_vcsr]\n\t"
  

• 	: [tmp_vcsr] "=&r" (tmp_vcsr) : [vcsr] "r" (src->vcsr));
  

Similarly, this would be a lot easier to parse with csr_write() instead of inline assembly.

Regards, Samuel

• if (restore_fpu)
  

• 	csr_set(CSR_SSTATUS, status);
  

• } else {

• asm volatile (
  

• 	"csrw	" __stringify(CSR_VCSR) ", %[vcsr]\n\t"
  

• 	: : [vcsr] "r" (src->vcsr));
  

• }

} static inline void __riscv_v_vstate_save(struct __riscv_v_ext_state *save_to, @@ -107,19 +218,33 @@ static inline void __riscv_v_vstate_save(struct __riscv_v_ext_state *save_to, riscv_v_enable(); __vstate_csr_save(save_to);

• asm volatile (

• ".option push\n\t"
  

• ".option arch, +v\n\t"
  

• "vsetvli	%0, x0, e8, m8, ta, ma\n\t"
  

• "vse8.v		v0, (%1)\n\t"
  

• "add		%1, %1, %0\n\t"
  

• "vse8.v		v8, (%1)\n\t"
  

• "add		%1, %1, %0\n\t"
  

• "vse8.v		v16, (%1)\n\t"
  

• "add		%1, %1, %0\n\t"
  

• "vse8.v		v24, (%1)\n\t"
  

• ".option pop\n\t"
  

• : "=&r" (vl) : "r" (datap) : "memory");
  

• if (has_xtheadvector()) {

• asm volatile (
  

• 	"mv t0, %0\n\t"
  

• 	THEAD_VSETVLI_T4X0E8M8D1
  

• 	THEAD_VSB_V_V0T0
  

• 	"add		t0, t0, t4\n\t"
  

• 	THEAD_VSB_V_V0T0
  

• 	"add		t0, t0, t4\n\t"
  

• 	THEAD_VSB_V_V0T0
  

• 	"add		t0, t0, t4\n\t"
  

• 	THEAD_VSB_V_V0T0
  

• 	: : "r" (datap) : "memory", "t0", "t4");
  

• } else {

• asm volatile (
  

• 	".option push\n\t"
  

• 	".option arch, +v\n\t"
  

• 	"vsetvli	%0, x0, e8, m8, ta, ma\n\t"
  

• 	"vse8.v		v0, (%1)\n\t"
  

• 	"add		%1, %1, %0\n\t"
  

• 	"vse8.v		v8, (%1)\n\t"
  

• 	"add		%1, %1, %0\n\t"
  

• 	"vse8.v		v16, (%1)\n\t"
  

• 	"add		%1, %1, %0\n\t"
  

• 	"vse8.v		v24, (%1)\n\t"
  

• 	".option pop\n\t"
  

• 	: "=&r" (vl) : "r" (datap) : "memory");
  

• } riscv_v_disable();

} @@ -129,55 +254,77 @@ static inline void __riscv_v_vstate_restore(struct __riscv_v_ext_state *restore_ unsigned long vl; riscv_v_enable();

• asm volatile (

• ".option push\n\t"
  

• ".option arch, +v\n\t"
  

• "vsetvli	%0, x0, e8, m8, ta, ma\n\t"
  

• "vle8.v		v0, (%1)\n\t"
  

• "add		%1, %1, %0\n\t"
  

• "vle8.v		v8, (%1)\n\t"
  

• "add		%1, %1, %0\n\t"
  

• "vle8.v		v16, (%1)\n\t"
  

• "add		%1, %1, %0\n\t"
  

• "vle8.v		v24, (%1)\n\t"
  

• ".option pop\n\t"
  

• : "=&r" (vl) : "r" (datap) : "memory");
  

• if (has_xtheadvector()) {

• asm volatile (
  

• 	"mv t0, %0\n\t"
  

• 	THEAD_VSETVLI_T4X0E8M8D1
  

• 	THEAD_VLB_V_V0T0
  

• 	"add		t0, t0, t4\n\t"
  

• 	THEAD_VLB_V_V0T0
  

• 	"add		t0, t0, t4\n\t"
  

• 	THEAD_VLB_V_V0T0
  

• 	"add		t0, t0, t4\n\t"
  

• 	THEAD_VLB_V_V0T0
  

• 	: : "r" (datap) : "memory", "t0", "t4");
  

• } else {

• asm volatile (
  

• 	".option push\n\t"
  

• 	".option arch, +v\n\t"
  

• 	"vsetvli	%0, x0, e8, m8, ta, ma\n\t"
  

• 	"vle8.v		v0, (%1)\n\t"
  

• 	"add		%1, %1, %0\n\t"
  

• 	"vle8.v		v8, (%1)\n\t"
  

• 	"add		%1, %1, %0\n\t"
  

• 	"vle8.v		v16, (%1)\n\t"
  

• 	"add		%1, %1, %0\n\t"
  

• 	"vle8.v		v24, (%1)\n\t"
  

• 	".option pop\n\t"
  

• 	: "=&r" (vl) : "r" (datap) : "memory");
  

• } __vstate_csr_restore(restore_from); riscv_v_disable();

} static inline void __riscv_v_vstate_discard(void) {

• unsigned long vl, vtype_inval = 1UL << (BITS_PER_LONG - 1);

• unsigned long vtype_inval = 1UL << (BITS_PER_LONG - 1);

riscv_v_enable();

• if (has_xtheadvector())

• asm volatile (THEAD_VSETVLI_X0X0E8M8D1);
  

• else

• asm volatile (
  

• 	".option push\n\t"
  

• 	".option arch, +v\n\t"
  

• 	"vsetvli	x0, x0, e8, m8, ta, ma\n\t"
  

• 	".option pop\n\t");
  

• asm volatile ( ".option push\n\t" ".option arch, +v\n\t"

• "vsetvli	%0, x0, e8, m8, ta, ma\n\t"
  

  "vmv.v.i v0, -1\n\t" "vmv.v.i v8, -1\n\t" "vmv.v.i v16, -1\n\t" "vmv.v.i v24, -1\n\t"

• "vsetvl		%0, x0, %1\n\t"
  

• "vsetvl		x0, x0, %0\n\t"
  

  ".option pop\n\t"

• : "=&r" (vl) : "r" (vtype_inval) : "memory");
  

• : : "r" (vtype_inval));
  

• riscv_v_disable();

} static inline void riscv_v_vstate_discard(struct pt_regs *regs) {

• if ((regs->status & SR_VS) == SR_VS_OFF)

• return;
  

• __riscv_v_vstate_discard();
• __riscv_v_vstate_dirty(regs);

• if (riscv_v_vstate_query(regs)) {

• __riscv_v_vstate_discard();
  

• __riscv_v_vstate_dirty(regs);
  

• }

} static inline void riscv_v_vstate_save(struct __riscv_v_ext_state *vstate, struct pt_regs *regs) {

• if ((regs->status & SR_VS) == SR_VS_DIRTY) {

• if (__riscv_v_vstate_check(regs->status, DIRTY)) { __riscv_v_vstate_save(vstate, vstate->datap); __riscv_v_vstate_clean(regs); }

@@ -186,7 +333,7 @@ static inline void riscv_v_vstate_save(struct __riscv_v_ext_state *vstate, static inline void riscv_v_vstate_restore(struct __riscv_v_ext_state *vstate, struct pt_regs *regs) {

• if ((regs->status & SR_VS) != SR_VS_OFF) {

• if (riscv_v_vstate_query(regs)) { __riscv_v_vstate_restore(vstate, vstate->datap); __riscv_v_vstate_clean(regs); }

@@ -195,7 +342,7 @@ static inline void riscv_v_vstate_restore(struct __riscv_v_ext_state *vstate, static inline void riscv_v_vstate_set_restore(struct task_struct *task, struct pt_regs *regs) {

• if ((regs->status & SR_VS) != SR_VS_OFF) {

• if (riscv_v_vstate_query(regs)) { set_tsk_thread_flag(task, TIF_RISCV_V_DEFER_RESTORE); riscv_v_vstate_on(regs); }

diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c index 077be4ab1f9a..180f7eae9086 100644 --- a/arch/riscv/kernel/cpufeature.c +++ b/arch/riscv/kernel/cpufeature.c @@ -789,7 +789,7 @@ void __init riscv_fill_hwcap(void) elf_hwcap &= ~COMPAT_HWCAP_ISA_F; }

• if (elf_hwcap & COMPAT_HWCAP_ISA_V) {

• if (elf_hwcap & COMPAT_HWCAP_ISA_V || has_xtheadvector_no_alternatives()) { riscv_v_setup_vsize(); /*
  • ISA string in device tree might have 'v' flag, but

diff --git a/arch/riscv/kernel/kernel_mode_vector.c b/arch/riscv/kernel/kernel_mode_vector.c index 6afe80c7f03a..99972a48e86b 100644 --- a/arch/riscv/kernel/kernel_mode_vector.c +++ b/arch/riscv/kernel/kernel_mode_vector.c @@ -143,7 +143,7 @@ static int riscv_v_start_kernel_context(bool *is_nested) /* Transfer the ownership of V from user to kernel, then save */ riscv_v_start(RISCV_PREEMPT_V | RISCV_PREEMPT_V_DIRTY);

• if ((task_pt_regs(current)->status & SR_VS) == SR_VS_DIRTY) {

• if (__riscv_v_vstate_check(task_pt_regs(current)->status, DIRTY)) { uvstate = &current->thread.vstate; __riscv_v_vstate_save(uvstate, uvstate->datap); }

@@ -160,7 +160,7 @@ asmlinkage void riscv_v_context_nesting_start(struct pt_regs *regs) return; depth = riscv_v_ctx_get_depth();

• if (depth == 0 && (regs->status & SR_VS) == SR_VS_DIRTY)

• if (depth == 0 && __riscv_v_vstate_check(regs->status, DIRTY)) riscv_preempt_v_set_dirty();

riscv_v_ctx_depth_inc(); @@ -208,7 +208,7 @@ void kernel_vector_begin(void) { bool nested = false;

• if (WARN_ON(!has_vector()))

• if (WARN_ON(!(has_vector() || has_xtheadvector()))) return;

BUG_ON(!may_use_simd()); @@ -236,7 +236,7 @@ EXPORT_SYMBOL_GPL(kernel_vector_begin); */ void kernel_vector_end(void) {

• if (WARN_ON(!has_vector()))

• if (WARN_ON(!(has_vector() || has_xtheadvector()))) return;

riscv_v_disable(); diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index e4bc61c4e58a..191023decd16 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -176,7 +176,7 @@ void flush_thread(void) void arch_release_task_struct(struct task_struct *tsk) { /* Free the vector context of datap. */

• if (has_vector())

• if (has_vector() || has_xtheadvector()) riscv_v_thread_free(tsk);

} @@ -222,7 +222,7 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) p->thread.s[0] = 0; } p->thread.riscv_v_flags = 0;

• if (has_vector())

• if (has_vector() || has_xtheadvector()) riscv_v_thread_alloc(p); p->thread.ra = (unsigned long)ret_from_fork; p->thread.sp = (unsigned long)childregs; /* kernel sp */

diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c index 5a2edd7f027e..1d5e4b3ca9e1 100644 --- a/arch/riscv/kernel/signal.c +++ b/arch/riscv/kernel/signal.c @@ -189,7 +189,7 @@ static long restore_sigcontext(struct pt_regs *regs, return 0; case RISCV_V_MAGIC:

• 	if (!has_vector() || !riscv_v_vstate_query(regs) ||
  

• 	if (!(has_vector() || has_xtheadvector()) || !riscv_v_vstate_query(regs) ||
      size != riscv_v_sc_size)
  	return -EINVAL;
  

@@ -211,7 +211,7 @@ static size_t get_rt_frame_size(bool cal_all) frame_size = sizeof(*frame);

• if (has_vector()) {

• if (has_vector() || has_xtheadvector()) { if (cal_all || riscv_v_vstate_query(task_pt_regs(current))) total_context_size += riscv_v_sc_size; }

@@ -284,7 +284,7 @@ static long setup_sigcontext(struct rt_sigframe __user *frame, if (has_fpu()) err |= save_fp_state(regs, &sc->sc_fpregs); /* Save the vector state. */

• if (has_vector() && riscv_v_vstate_query(regs))

• if ((has_vector() || has_xtheadvector()) && riscv_v_vstate_query(regs)) err |= save_v_state(regs, (void __user **)&sc_ext_ptr); /* Write zero to fp-reserved space and check it on restore_sigcontext */ err |= __put_user(0, &sc->sc_extdesc.reserved);

diff --git a/arch/riscv/kernel/vector.c b/arch/riscv/kernel/vector.c index 3ba2f2432483..83126995f61a 100644 --- a/arch/riscv/kernel/vector.c +++ b/arch/riscv/kernel/vector.c @@ -63,7 +63,7 @@ int riscv_v_setup_vsize(void) void __init riscv_v_setup_ctx_cache(void) {

• if (!has_vector())

• if (!(has_vector() || has_xtheadvector())) return;

riscv_v_user_cachep = kmem_cache_create_usercopy("riscv_vector_ctx", @@ -184,7 +184,8 @@ bool riscv_v_first_use_handler(struct pt_regs *regs) u32 insn = (u32)regs->badaddr; /* Do not handle if V is not supported, or disabled */

• if (!(ELF_HWCAP & COMPAT_HWCAP_ISA_V))

• if (!(ELF_HWCAP & COMPAT_HWCAP_ISA_V) &&

•    !(has_xtheadvector() && riscv_v_vstate_ctrl_user_allowed()))
  

  return false;

/* If V has been enabled then it is not the first-use trap */ @@ -223,7 +224,7 @@ void riscv_v_vstate_ctrl_init(struct task_struct *tsk) bool inherit; int cur, next;

• if (!has_vector())

• if (!(has_vector() || has_xtheadvector())) return;

next = riscv_v_ctrl_get_next(tsk); @@ -245,7 +246,7 @@ void riscv_v_vstate_ctrl_init(struct task_struct *tsk) long riscv_v_vstate_ctrl_get_current(void) {

• if (!has_vector())

• if (!(has_vector() || has_xtheadvector())) return -EINVAL;

return current->thread.vstate_ctrl & PR_RISCV_V_VSTATE_CTRL_MASK; @@ -256,7 +257,7 @@ long riscv_v_vstate_ctrl_set_current(unsigned long arg) bool inherit; int cur, next;

• if (!has_vector())

• if (!(has_vector() || has_xtheadvector())) return -EINVAL;

if (arg & ~PR_RISCV_V_VSTATE_CTRL_MASK) @@ -306,7 +307,7 @@ static struct ctl_table riscv_v_default_vstate_table[] = { static int __init riscv_v_sysctl_init(void) {

• if (has_vector())

• if (has_vector() || has_xtheadvector()) if (!register_sysctl("abi", riscv_v_default_vstate_table)) return -EINVAL; return 0;