On Tue, Aug 11, 2020 at 1:41 AM Anup Patel <a...@brainfault.org> wrote: > > On Tue, Aug 11, 2020 at 12:07 PM Qiu Wenbo <qiuwe...@phytium.com.cn> wrote: > > > > Exception vector is missing on nommu platform and it is a big issue. > > This patch is tested in Sipeed MAIX Bit Dev Board. > > > > Fixes: 79b1feba5455 ("RISC-V: Setup exception vector early") > > Signed-off-by: Qiu Wenbo <qiuwe...@phytium.com.cn>
Thanks for testing it on the kendryte board. > > --- > > arch/riscv/kernel/smpboot.c | 1 + > > arch/riscv/kernel/traps.c | 11 ++++++++++- > > 2 files changed, 11 insertions(+), 1 deletion(-) > > > > diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c > > index 356825a57551..23cde0ceb39d 100644 > > --- a/arch/riscv/kernel/smpboot.c > > +++ b/arch/riscv/kernel/smpboot.c > > @@ -154,6 +154,7 @@ asmlinkage __visible void smp_callin(void) > > mmgrab(mm); > > current->active_mm = mm; > > > > + trap_init(); > > notify_cpu_starting(curr_cpuid); > > update_siblings_masks(curr_cpuid); > > set_cpu_online(curr_cpuid, 1); > > diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c > > index ad14f4466d92..a390239818ae 100644 > > --- a/arch/riscv/kernel/traps.c > > +++ b/arch/riscv/kernel/traps.c > > @@ -174,7 +174,16 @@ int is_valid_bugaddr(unsigned long pc) > > } > > #endif /* CONFIG_GENERIC_BUG */ > > > > -/* stvec & scratch is already set from head.S */ > > +/* stvec & scratch is already set from head.S when mmu is enabled */ > > void trap_init(void) > > { > > +#ifndef CONFIG_MMU > > + /* > > + * Set sup0 scratch register to 0, indicating to exception vector > > + * that we are presently executing in the kernel > > + */ > > + csr_write(CSR_SCRATCH, 0); > > + /* Set the exception vector address */ > > + csr_write(CSR_TVEC, &handle_exception); > > +#endif > > } > > -- > > 2.28.0 > > > > This issue seems to be only on the latest master branch of > Linux stable tree so this fix need not be a stable fix. > > For MMU kernel, the CSR_TVEC is setup in relocate() function > called from secondary_start_common() function of head.S > > For NoMMU kernel, we should set CSR_TVEC directly in > secondary_start_common() function as "#else" case of the > "#ifdef CONFIG_MMU". > That would enable the trap only for secondary harts. But the exception vector on boot hart is still uninitialized. How about this change ? diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S index d0c5c316e9bb..7822054dbd88 100644 --- a/arch/riscv/kernel/head.S +++ b/arch/riscv/kernel/head.S @@ -77,16 +77,6 @@ relocate: csrw CSR_SATP, a0 .align 2 1: - /* 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 - /* Reload the global pointer */ .option push .option norelax @@ -144,9 +134,23 @@ 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 +244,7 @@ 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) > Regards, > Anup > > _______________________________________________ > linux-riscv mailing list > linux-ri...@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv -- Regards, Atish