Re: [PATCH v9 29/36] x86/fred: FRED entry/exit and dispatch code

["H. Peter Anvin" <hpa@xxxxxxxxx>]

On 7/30/23 23:41, Xin Li wrote:
> +
> +static DEFINE_FRED_HANDLER(fred_sw_interrupt_user)
> +{
> +       /*
> +        * In compat mode INT $0x80 (32bit system call) is
> +        * performance-critical. Handle it first.
> +        */
> +       if (IS_ENABLED(CONFIG_IA32_EMULATION) &&
> +           likely(regs->vector == IA32_SYSCALL_VECTOR)) {
> +               regs->orig_ax = regs->ax;
> +               regs->ax = -ENOSYS;
> +               return do_int80_syscall_32(regs);
> +       }
We can presumably drop the early out here as well...

> +
> +       /*
> +        * Some software exceptions can also be triggered as
> +        * int instructions, for historical reasons.
> +        */
> +       switch (regs->vector) {
> +       case X86_TRAP_BP:
> +       case X86_TRAP_OF:
> +               fred_emulate_trap(regs);
> +               break;
> +       default:
> +               regs->vector = X86_TRAP_GP;
> +               fred_emulate_fault(regs);
> +               break;
> +       }
> +}
> +