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riscv: vector: Support xtheadvector save/restore

Browse source 
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>
Tested-by: Yangyu Chen <cyy@cyyself.name>
Link: https://lore.kernel.org/r/20241113-xtheadvector-v11-9-236c22791ef9@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Charlie Jenkins 2024-11-13 18:21:15 -08:00 • committed by Palmer Dabbelt
parent 01e3313e34
commit d863910eab
No known key found for this signature in database
GPG key ID: 2E1319F35FBB1889
8 changed files with 198 additions and 68 deletions
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6
arch/riscv/include/asm/csr.h
View file

@ -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)

2
arch/riscv/include/asm/switch_to.h
View file

@ -117,7 +117,7 @@ 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(); \

222
arch/riscv/include/asm/vector.h
View file

@ -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);
@ -41,39 +62,62 @@ static __always_inline bool has_vector(void)
return riscv_has_extension_unlikely(RISCV_ISA_EXT_ZVE32X);
}
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)
@ -82,10 +126,36 @@ 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()) {
unsigned long status;
/*
* 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.
*/
status = csr_read_set(CSR_STATUS, SR_FS_DIRTY);
dest->vcsr = csr_read(CSR_VXSAT) | csr_read(CSR_VXRM) << CSR_VXRM_SHIFT;
dest->vlenb = riscv_v_vsize / 32;
if ((status & SR_FS) != SR_FS_DIRTY)
csr_write(CSR_STATUS, status);
} else {
dest->vcsr = csr_read(CSR_VCSR);
dest->vlenb = csr_read(CSR_VLENB);
}
}
static __always_inline void __vstate_csr_restore(struct __riscv_v_ext_state *src)
@ -96,9 +166,25 @@ 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()) {
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.
*/
status = csr_read_set(CSR_STATUS, SR_FS_DIRTY);
csr_write(CSR_VXRM, (src->vcsr >> CSR_VXRM_SHIFT) & CSR_VXRM_MASK);
csr_write(CSR_VXSAT, src->vcsr & CSR_VXSAT_MASK);
if ((status & SR_FS) != SR_FS_DIRTY)
csr_write(CSR_STATUS, status);
} else {
csr_write(CSR_VCSR, src->vcsr);
}
}
static inline void __riscv_v_vstate_save(struct __riscv_v_ext_state *save_to,
@ -108,19 +194,33 @@ 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, +zve32x\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, +zve32x\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();
}
@ -130,19 +230,33 @@ 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, +zve32x\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, +zve32x\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();
}
@ -152,33 +266,41 @@ static inline void __riscv_v_vstate_discard(void)
unsigned long vl, vtype_inval = 1UL << (BITS_PER_LONG - 1);
riscv_v_enable();
if (has_xtheadvector())
asm volatile (THEAD_VSETVLI_T4X0E8M8D1 : : : "t4");
else
asm volatile (
".option push\n\t"
".option arch, +zve32x\n\t"
"vsetvli %0, x0, e8, m8, ta, ma\n\t"
".option pop\n\t": "=&r" (vl));
asm volatile (
".option push\n\t"
".option arch, +zve32x\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"
".option pop\n\t"
: "=&r" (vl) : "r" (vtype_inval) : "memory");
: "=&r" (vl) : "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);
}
@ -187,7 +309,7 @@ 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);
}
@ -196,7 +318,7 @@ 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);
}
@ -270,6 +392,8 @@ struct pt_regs;
static inline int riscv_v_setup_vsize(void) { return -EOPNOTSUPP; }
static __always_inline bool has_vector(void) { return false; }
static __always_inline bool insn_is_vector(u32 insn_buf) { return false; }
static __always_inline bool has_xtheadvector_no_alternatives(void) { return false; }
static __always_inline bool has_xtheadvector(void) { return false; }
static inline bool riscv_v_first_use_handler(struct pt_regs *regs) { return false; }
static inline bool riscv_v_vstate_query(struct pt_regs *regs) { return false; }
static inline bool riscv_v_vstate_ctrl_user_allowed(void) { return false; }

6
arch/riscv/kernel/cpufeature.c
View file

@ -874,8 +874,7 @@ static int __init riscv_fill_hwcap_from_ext_list(unsigned long *isa2hwcap)
riscv_fill_vendor_ext_list(cpu);
}
if (riscv_isa_vendor_extension_available(THEAD_VENDOR_ID, XTHEADVECTOR) &&
has_thead_homogeneous_vlenb() < 0) {
if (has_xtheadvector_no_alternatives() && has_thead_homogeneous_vlenb() < 0) {
pr_warn("Unsupported heterogeneous vlenb detected, vector extension disabled.\n");
disable_xtheadvector();
}
@ -932,7 +931,8 @@ void __init riscv_fill_hwcap(void)
elf_hwcap &= ~COMPAT_HWCAP_ISA_F;
}
if (__riscv_isa_extension_available(NULL, RISCV_ISA_EXT_ZVE32X)) {
if (__riscv_isa_extension_available(NULL, RISCV_ISA_EXT_ZVE32X) ||
has_xtheadvector_no_alternatives()) {
/*
* This cannot fail when called on the boot hart
*/

8
arch/riscv/kernel/kernel_mode_vector.c
View file

@ -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();

4
arch/riscv/kernel/process.c
View file

@ -190,7 +190,7 @@ 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);
}
@ -240,7 +240,7 @@ 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 */

6
arch/riscv/kernel/signal.c
View file

@ -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);

12
arch/riscv/kernel/vector.c
View file

@ -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",
@ -183,7 +183,7 @@ bool riscv_v_first_use_handler(struct pt_regs *regs)
u32 __user *epc = (u32 __user *)regs->epc;
u32 insn = (u32)regs->badaddr;
if (!has_vector())
if (!(has_vector() || has_xtheadvector()))
return false;
/* Do not handle if V is not supported, or disabled */
@ -226,7 +226,7 @@ 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);
@ -248,7 +248,7 @@ 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;
@ -259,7 +259,7 @@ 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)
@ -309,7 +309,7 @@ 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;