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Message-ID: <CAJF2gTR2_WYAAdkxPH0Z3ejKu1W0J3fK43vLoYkPGnzLK6q3Ww@mail.gmail.com>
Date: Sun, 31 May 2020 23:28:55 +0800
From: Guo Ren <guoren@...nel.org>
To: Greentime Hu <greentime.hu@...ive.com>
Cc: Guo Ren <guoren@...ux.alibaba.com>,
Vincent Chen <vincent.chen@...ive.com>,
Paul Walmsley <paul.walmsley@...ive.com>,
palmerdabbelt@...gle.com,
linux-riscv <linux-riscv@...ts.infradead.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
oleg@...hat.com
Subject: Re: [RFC PATCH v4 12/13] riscv: Add sigcontext save/restore for vector
Hi Greentime,
On Tue, May 26, 2020 at 3:03 PM Greentime Hu <greentime.hu@...ive.com> wrote:
>
> From: Guo Ren <guoren@...ux.alibaba.com>
>
> This patch adds sigcontext save/restore for vector. The vector registers
> will be saved in datap pointer. The datap pointer will be allocaed
> dynamically when the task needs in kernel space. The datap pointer will
> be set right after the __riscv_v_state data structure to save all the
> vector registers in the signal handler stack.
>
> [greentime.hu@...ive.com: add support for dynamic vlen]
> Signed-off-by: Greentime Hu <greentime.hu@...ive.com>
> Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
> ---
> arch/riscv/include/uapi/asm/sigcontext.h | 2 +
> arch/riscv/kernel/signal.c | 92 +++++++++++++++++++++++-
> 2 files changed, 91 insertions(+), 3 deletions(-)
>
> diff --git a/arch/riscv/include/uapi/asm/sigcontext.h b/arch/riscv/include/uapi/asm/sigcontext.h
> index 84f2dfcfdbce..4217f3f1c8ba 100644
> --- a/arch/riscv/include/uapi/asm/sigcontext.h
> +++ b/arch/riscv/include/uapi/asm/sigcontext.h
> @@ -8,6 +8,7 @@
>
> #include <asm/ptrace.h>
>
> +#define RVV_MAGIC 0x53465457
> /*
> * Signal context structure
> *
> @@ -17,6 +18,7 @@
> struct sigcontext {
> struct user_regs_struct sc_regs;
> union __riscv_fp_state sc_fpregs;
> + struct __riscv_v_state sc_vregs;
> };
>
> #endif /* _UAPI_ASM_RISCV_SIGCONTEXT_H */
> diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c
> index 17ba190e84a5..9ada6f74bb95 100644
> --- a/arch/riscv/kernel/signal.c
> +++ b/arch/riscv/kernel/signal.c
> @@ -83,6 +83,80 @@ static long save_fp_state(struct pt_regs *regs,
> #define restore_fp_state(task, regs) (0)
> #endif
>
> +#ifdef CONFIG_VECTOR
> +static long restore_v_state(struct pt_regs *regs, struct sigcontext *sc)
> +{
> + long err;
> + struct __riscv_v_state __user *state = &sc->sc_vregs;
> + void *datap;
> + __u32 magic;
> +
> + /* Get magic number and check it. */
> + err = __get_user(magic, &state->magic);
> + if (unlikely(err))
> + return err;
> +
> + if (magic != RVV_MAGIC)
> + return -EINVAL;
> +
> + /* Copy everything of __riscv_v_state except datap. */
> + err = __copy_from_user(¤t->thread.vstate, state,
> + RISCV_V_STATE_DATAP);
> + if (unlikely(err))
> + return err;
> +
> + /* Copy the pointer datap itself. */
> + err = __get_user(datap, &state->datap);
> + if (unlikely(err))
> + return err;
> +
> +
> + /* Copy the whole vector content from user space datap. */
> + err = __copy_from_user(current->thread.vstate.datap, datap,
> + current->thread.vstate.size);
> + if (unlikely(err))
> + return err;
> +
> + vstate_restore(current, regs);
> +
> + return err;
> +}
> +
> +static long save_v_state(struct pt_regs *regs, struct sigcontext *sc)
> +{
> + long err;
> + struct __riscv_v_state __user *state = &sc->sc_vregs;
> + /* Set the datap right after the sigcntext structure. */
> + void *datap = sc + 1;
> +
> + vstate_save(current, regs);
> + /* Copy everything of vstate but datap. */
> + err = __copy_to_user(state, ¤t->thread.vstate,
> + RISCV_V_STATE_DATAP);
> + if (unlikely(err))
> + return err;
> +
> + /* Copy the magic number. */
> + err = __put_user(RVV_MAGIC, &state->magic);
> + if (unlikely(err))
> + return err;
> +
> + /* Copy the pointer datap itself. */
> + err = __put_user(datap, &state->datap);
> + if (unlikely(err))
> + return err;
> +
> + /* Copy the whole vector content to user space datap. */
> + err = __copy_to_user(datap, current->thread.vstate.datap,
> + current->thread.vstate.size);
> +
> + return err;
> +}
> +#else
> +#define save_v_state(task, regs) (0)
> +#define restore_v_state(task, regs) (0)
> +#endif
> +
> static long restore_sigcontext(struct pt_regs *regs,
> struct sigcontext __user *sc)
> {
> @@ -92,6 +166,9 @@ static long restore_sigcontext(struct pt_regs *regs,
> /* Restore the floating-point state. */
> if (has_fpu)
> err |= restore_fp_state(regs, &sc->sc_fpregs);
> + /* Restore the vector state. */
> + if (has_vector)
> + err |= restore_v_state(regs, sc);
> return err;
> }
>
> @@ -101,13 +178,16 @@ SYSCALL_DEFINE0(rt_sigreturn)
> struct rt_sigframe __user *frame;
> struct task_struct *task;
> sigset_t set;
> + size_t frame_size = sizeof(*frame);
>
> /* Always make any pending restarted system calls return -EINTR */
> current->restart_block.fn = do_no_restart_syscall;
>
> frame = (struct rt_sigframe __user *)regs->sp;
>
> - if (!access_ok(frame, sizeof(*frame)))
> + if (has_vector)
> + frame_size += current->thread.vstate.size;
Shall we force all applications save & restore vr regs ? Maybe we can
utilize vs dirty bit
> + if (!access_ok(frame, frame_size))
> goto badframe;
>
> if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
> @@ -145,6 +225,9 @@ static long setup_sigcontext(struct rt_sigframe __user *frame,
> /* Save the floating-point state. */
> if (has_fpu)
> err |= save_fp_state(regs, &sc->sc_fpregs);
> + /* Save the vector state. */
> + if (has_vector)
> + err |= save_v_state(regs, sc);
> return err;
> }
>
> @@ -176,9 +259,12 @@ static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
> {
> struct rt_sigframe __user *frame;
> long err = 0;
> + size_t frame_size = sizeof(*frame);
>
> - frame = get_sigframe(ksig, regs, sizeof(*frame));
> - if (!access_ok(frame, sizeof(*frame)))
> + if (has_vector)
> + frame_size += current->thread.vstate.size;
> + frame = get_sigframe(ksig, regs, frame_size);
> + if (!access_ok(frame, frame_size))
> return -EFAULT;
>
> err |= copy_siginfo_to_user(&frame->info, &ksig->info);
> --
> 2.26.2
>
>
--
Best Regards
Guo Ren
ML: https://lore.kernel.org/linux-csky/
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