Re: [PATCH urgent] MIPS: fix micro-assembly overflow in set_except_vector

[David Daney <ddaney@caviumnetworks.com>]

Florian Fainelli wrote:
> Commit 24a6d9866c5f15ba7e5b14dc17be4b6edba21d0e broke
> the installation of handlers for boards which have their
> handlers above a 1 << 26 address. Fix this by making sure that
> jump_mask does not excess 0xfc000000 and add the missing ~ operator
> to jump_mask when jumping to the handler address.
>
> Reported-by: Maxime Bizon <mbizon@freebox.fr>
> Signed-off-by: Florian Fainelli <florian@openwrt.org>
Acked-by: David Daney <ddaney@caviumnetworks.com>

> ---
> diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
> index 7693929..40d94c3 100644
> --- a/arch/mips/kernel/traps.c
> +++ b/arch/mips/kernel/traps.c
> @@ -1279,11 +1279,11 @@ void __init *set_except_vector(int n, void *addr)
>  
>  	exception_handlers[n] = handler;
>         if (n == 0 && cpu_has_divec) {
> -               unsigned long jump_mask = ~((1 << 28) - 1);
> +               unsigned long jump_mask = ~((1 << 26) - 1);
>                 u32 *buf = (u32 *)(ebase + 0x200);
>                 unsigned int k0 = 26;
>                 if ((handler & jump_mask) == ((ebase + 0x200) & jump_mask)) {
> -                       uasm_i_j(&buf, handler & jump_mask);
> +                       uasm_i_j(&buf, handler & ~jump_mask);
>                         uasm_i_nop(&buf);
>                 } else {
>                         UASM_i_LA(&buf, k0, handler);