Messages in this thread | | | From | Anup Patel <> | Date | Tue, 11 Aug 2020 14:10:40 +0530 | Subject | Re: [PATCH] riscv: Setup exception vector for K210 properly |
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On Tue, Aug 11, 2020 at 12:07 PM Qiu Wenbo <qiuwenbo@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 <qiuwenbo@phytium.com.cn> > --- > 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".
Regards, Anup
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