[PATCH -next v15 08/19] riscv: Introduce struct/helpers to save/restore per-task Vector state
Guo Ren
guoren at kernel.org
Tue Mar 21 18:54:16 PDT 2023
On Fri, Mar 17, 2023 at 7:37 PM Andy Chiu <andy.chiu at sifive.com> wrote:
>
> From: Greentime Hu <greentime.hu at sifive.com>
>
> Add vector state context struct to be added later in thread_struct. And
> prepare low-level helper functions to save/restore vector contexts.
>
> This include Vector Regfile and CSRs holding dynamic configuration state
> (vstart, vl, vtype, vcsr). The Vec Register width could be implementation
> defined, but same for all processes, so that is saved separately.
>
> This is not yet wired into final thread_struct - will be done when
> __switch_to actually starts doing this in later patches.
>
> Given the variable (and potentially large) size of regfile, they are
> saved in dynamically allocated memory, pointed to by datap pointer in
> __riscv_v_ext_state.
>
> Co-developed-by: Vincent Chen <vincent.chen at sifive.com>
> Signed-off-by: Vincent Chen <vincent.chen at sifive.com>
> Signed-off-by: Greentime Hu <greentime.hu at sifive.com>
> Signed-off-by: Vineet Gupta <vineetg at rivosinc.com>
> Signed-off-by: Andy Chiu <andy.chiu at sifive.com>
> ---
> arch/riscv/include/asm/vector.h | 97 ++++++++++++++++++++++++++++
> arch/riscv/include/uapi/asm/ptrace.h | 17 +++++
> 2 files changed, 114 insertions(+)
>
> diff --git a/arch/riscv/include/asm/vector.h b/arch/riscv/include/asm/vector.h
> index 18448e24d77b..c7143b7d64d1 100644
> --- a/arch/riscv/include/asm/vector.h
> +++ b/arch/riscv/include/asm/vector.h
> @@ -10,8 +10,10 @@
>
> #ifdef CONFIG_RISCV_ISA_V
>
> +#include <linux/stringify.h>
> #include <asm/hwcap.h>
> #include <asm/csr.h>
> +#include <asm/asm.h>
>
> extern unsigned long riscv_v_vsize;
> void riscv_v_setup_vsize(void);
> @@ -21,6 +23,26 @@ static __always_inline bool has_vector(void)
> return riscv_has_extension_likely(RISCV_ISA_EXT_v);
> }
>
> +static inline void __riscv_v_vstate_clean(struct pt_regs *regs)
> +{
> + regs->status = (regs->status & ~SR_VS) | SR_VS_CLEAN;
> +}
> +
> +static inline void riscv_v_vstate_off(struct pt_regs *regs)
> +{
> + regs->status = (regs->status & ~SR_VS) | SR_VS_OFF;
> +}
> +
> +static inline void riscv_v_vstate_on(struct pt_regs *regs)
> +{
> + regs->status = (regs->status & ~SR_VS) | SR_VS_INITIAL;
> +}
> +
> +static inline bool riscv_v_vstate_query(struct pt_regs *regs)
> +{
> + return (regs->status & SR_VS) != 0;
> +}
> +
> static __always_inline void riscv_v_enable(void)
> {
> csr_set(CSR_SSTATUS, SR_VS);
> @@ -31,11 +53,86 @@ static __always_inline void riscv_v_disable(void)
> csr_clear(CSR_SSTATUS, SR_VS);
> }
>
> +static __always_inline void __vstate_csr_save(struct __riscv_v_ext_state *dest)
> +{
> + asm volatile (
> + "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"
> + : "=r" (dest->vstart), "=r" (dest->vtype), "=r" (dest->vl),
> + "=r" (dest->vcsr) : :);
> +}
> +
> +static __always_inline void __vstate_csr_restore(struct __riscv_v_ext_state *src)
> +{
> + asm volatile (
> + ".option push\n\t"
> + ".option arch, +v\n\t"
> + "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) :);
> +}
> +
> +static inline void __riscv_v_vstate_save(struct __riscv_v_ext_state *save_to,
> + void *datap)
> +{
> + unsigned long vl;
> +
> + 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");
> + riscv_v_disable();
> +}
> +
> +static inline void __riscv_v_vstate_restore(struct __riscv_v_ext_state *restore_from,
> + void *datap)
> +{
> + 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");
> + __vstate_csr_restore(restore_from);
> + riscv_v_disable();
> +}
> +
> #else /* ! CONFIG_RISCV_ISA_V */
>
> +struct pt_regs;
> +
> static __always_inline bool has_vector(void) { return false; }
> +static inline bool riscv_v_vstate_query(struct pt_regs *regs) { return false; }
> #define riscv_v_vsize (0)
> #define riscv_v_setup_vsize() do {} while (0)
> +#define riscv_v_vstate_off(regs) do {} while (0)
> +#define riscv_v_vstate_on(regs) do {} while (0)
>
> #endif /* CONFIG_RISCV_ISA_V */
>
> diff --git a/arch/riscv/include/uapi/asm/ptrace.h b/arch/riscv/include/uapi/asm/ptrace.h
> index 882547f6bd5c..586786d023c4 100644
> --- a/arch/riscv/include/uapi/asm/ptrace.h
> +++ b/arch/riscv/include/uapi/asm/ptrace.h
> @@ -77,6 +77,23 @@ union __riscv_fp_state {
> struct __riscv_q_ext_state q;
> };
>
> +struct __riscv_v_ext_state {
> + unsigned long vstart;
> + unsigned long vl;
> + unsigned long vtype;
> + unsigned long vcsr;
> + void *datap;
> + /*
> + * In signal handler, datap will be set a correct user stack offset
> + * and vector registers will be copied to the address of datap
> + * pointer.
> + *
> + * In ptrace syscall, datap will be set to zero and the vector
> + * registers will be copied to the address right after this
> + * structure.
> + */
> +};
> +
> #endif /* __ASSEMBLY__ */
>
> #endif /* _UAPI_ASM_RISCV_PTRACE_H */
Reviewed-by: Guo Ren <guoren at kernel.org>
> --
> 2.17.1
>
--
Best Regards
Guo Ren
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