[PATCH] riscv: vector: only enable interrupts in the first-use trap

[Guo Ren]

On Sun, Jun 25, 2023 at 11:54 AM Andy Chiu <andy.chiu at sifive.com> wrote:
>
> The function irqentry_exit_to_user_mode() must be called with interrupt
> disabled. The caller of do_trap_insn_illegal() also assumes running
> without interrupts. So, we should turn off interrupts after
> riscv_v_first_use_handler() returns.
>
> Fixes: cd054837243b ("riscv: Allocate user's vector context in the first-use trap")
> Signed-off-by: Andy Chiu <andy.chiu at sifive.com>
> ---
>  arch/riscv/kernel/traps.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
> index 05ffdcd1424e..1595e246bda1 100644
> --- a/arch/riscv/kernel/traps.c
> +++ b/arch/riscv/kernel/traps.c
> @@ -149,12 +149,18 @@ DO_ERROR_INFO(do_trap_insn_fault,
>
>  asmlinkage __visible __trap_section void do_trap_insn_illegal(struct pt_regs *regs)
>  {
> +       bool handled;
> +
>         if (user_mode(regs)) {
>                 irqentry_enter_from_user_mode(regs);
>
>                 local_irq_enable();
>
> -               if (!riscv_v_first_use_handler(regs))
> +               handled = riscv_v_first_use_handler(regs);
How about making riscv_v_first_use_handler irq_disable safe?
--------
diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index 5158961ea977..545295045705 100644
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -153,8 +153,6 @@ asmlinkage __visible __trap_section void
do_trap_insn_illegal(struct pt_regs *re
        if (user_mode(regs)) {
                irqentry_enter_from_user_mode(regs);

-               local_irq_enable();
-
                if (!riscv_v_first_use_handler(regs))
                        do_trap_error(regs, SIGILL, ILL_ILLOPC, regs->epc,
                                      "Oops - illegal instruction");
diff --git a/arch/riscv/kernel/vector.c b/arch/riscv/kernel/vector.c
index f9c8e19ab301..7616c027ee64 100644
--- a/arch/riscv/kernel/vector.c
+++ b/arch/riscv/kernel/vector.c
@@ -84,7 +84,7 @@ static int riscv_v_thread_zalloc(void)
 {
        void *datap;

-       datap = kzalloc(riscv_v_vsize, GFP_KERNEL);
+       datap = kzalloc(riscv_v_vsize, GFP_KERNEL | GFP_ATOMIC);
        if (!datap)
                return -ENOMEM;
---------

> +
> +               local_irq_disable();
> +
> +               if (!handled)
>                         do_trap_error(regs, SIGILL, ILL_ILLOPC, regs->epc,
>                                       "Oops - illegal instruction");
>
> --
> 2.17.1
>


-- 
Best Regards
 Guo Ren