On Wed, Aug 12, 2020 at 10:44 PM Damien Le Moal <damien.lem...@wdc.com> wrote:
>
> On 2020/08/13 12:40, Qiu Wenbo wrote:
> > Exception vector is missing on nommu platform and that is an issue.
> > This patch is tested in Sipeed Maix Bit Dev Board.
> >
> > Fixes: 79b1feba5455 ("RISC-V: Setup exception vector early")
> > Suggested-by: Anup Patel <a...@brainfault.org>
> > Suggested-by: Atish Patra <ati...@atishpatra.org>
> > Signed-off-by: Qiu Wenbo <qiuwe...@phytium.com.cn>
>
> Please add a cc stable #5.8 tag. Kendryte support is in 5.8 stable.
>That won't be necessary as the patch that broke nommu (79b1feba5455) was part of the 1st PR sent towards 5.9-rc1. > > --- > > arch/riscv/kernel/head.S | 25 +++++++++++++++++-------- > > 1 file changed, 17 insertions(+), 8 deletions(-) > > > > diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S > > index d0c5c316e9bb..0a4e81b8dc79 100644 > > --- a/arch/riscv/kernel/head.S > > +++ b/arch/riscv/kernel/head.S > > @@ -77,16 +77,10 @@ relocate: > > csrw CSR_SATP, a0 > > .align 2 > > 1: > > - /* Set trap vector to exception handler */ > > - la a0, handle_exception > > + /* Set trap vector to spin forever to help debug */ > > + la a0, .Lsecondary_park > > csrw CSR_TVEC, a0 > > > > - /* > > - * Set sup0 scratch register to 0, indicating to exception vector that > > - * we are presently executing in kernel. > > - */ > > - csrw CSR_SCRATCH, zero > > - > > /* Reload the global pointer */ > > .option push > > .option norelax > > @@ -144,9 +138,23 @@ secondary_start_common: > > la a0, swapper_pg_dir > > call relocate > > #endif > > + call setup_trap_vector > > tail smp_callin > > #endif /* CONFIG_SMP */ > > > > +.align 2 > > +setup_trap_vector: > > + /* Set trap vector to exception handler */ > > + la a0, handle_exception > > + csrw CSR_TVEC, a0 > > + > > + /* > > + * Set sup0 scratch register to 0, indicating to exception vector that > > + * we are presently executing in kernel. > > + */ > > + csrw CSR_SCRATCH, zero > > + ret > > + > > .Lsecondary_park: > > /* We lack SMP support or have too many harts, so park this hart */ > > wfi > > @@ -240,6 +248,7 @@ clear_bss_done: > > call relocate > > #endif /* CONFIG_MMU */ > > > > + call setup_trap_vector > > /* Restore C environment */ > > la tp, init_task > > sw zero, TASK_TI_CPU(tp) > > > > > -- > Damien Le Moal > Western Digital Research -- Regards, Atish
