Messages in this thread | | | Subject | Re: [PATCH] LoongArch: Fix irq enable in exception handlers | From | Jinyang He <> | Date | Tue, 27 Dec 2022 17:30:19 +0800 |
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On 2022-12-27 15:37, Huacai Chen wrote: > Hi, Jinyang, > > Move die_if_kernel to irq disabled context to solve what?
For more strict logical. If the code flow go to die in die_if_kernel(), its interrupt state is enable, that means it may cause schedule. So I think it is better to call die_if_kernel() firstly.
> And LBT is > surely allowed to be triggered in kernel context.
I'm not familar with lbt, I just not see any lbt codes in kernel. Plz, how lbt exception triggered, and how kernel trigger lbt exception?
Thanks,
Jinyang
> > Huacai > > On Wed, Dec 21, 2022 at 3:43 PM Jinyang He <hejinyang@loongson.cn> wrote: >> The interrupt state can be got by regs->csr_prmd. Once previous >> interrupt state is disable, we shouldn't enable interrupt if we >> triggered exception which can be triggered in kernel mode. So >> conditionally enable interrupt. For those do_\exception which >> can not triggered in kernel mode but need enable interrupt, call >> die_if_kernel() firstly. And for do_lsx, do_lasx and do_lbt cannot >> triggered in kernel mode, too. >> >> Signed-off-by: Jinyang He <hejinyang@loongson.cn> >> --- >> arch/loongarch/kernel/traps.c | 19 ++++++++++--------- >> 1 file changed, 10 insertions(+), 9 deletions(-) >> >> diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c >> index 1ea14f6c18d3..3ac7b32d1e15 100644 >> --- a/arch/loongarch/kernel/traps.c >> +++ b/arch/loongarch/kernel/traps.c >> @@ -340,9 +340,9 @@ asmlinkage void noinstr do_fpe(struct pt_regs *regs, unsigned long fcsr) >> >> /* Clear FCSR.Cause before enabling interrupts */ >> write_fcsr(LOONGARCH_FCSR0, fcsr & ~mask_fcsr_x(fcsr)); >> - local_irq_enable(); >> >> die_if_kernel("FP exception in kernel code", regs); >> + local_irq_enable(); >> >> sig = SIGFPE; >> fault_addr = (void __user *) regs->csr_era; >> @@ -432,7 +432,8 @@ asmlinkage void noinstr do_bp(struct pt_regs *regs) >> unsigned long era = exception_era(regs); >> irqentry_state_t state = irqentry_enter(regs); >> >> - local_irq_enable(); >> + if (regs->csr_prmd & CSR_PRMD_PIE) >> + local_irq_enable(); >> current->thread.trap_nr = read_csr_excode(); >> if (__get_inst(&opcode, (u32 *)era, user)) >> goto out_sigsegv; >> @@ -514,7 +515,8 @@ asmlinkage void noinstr do_ri(struct pt_regs *regs) >> unsigned int __user *era = (unsigned int __user *)exception_era(regs); >> irqentry_state_t state = irqentry_enter(regs); >> >> - local_irq_enable(); >> + if (regs->csr_prmd & CSR_PRMD_PIE) >> + local_irq_enable(); >> current->thread.trap_nr = read_csr_excode(); >> >> if (notify_die(DIE_RI, "RI Fault", regs, 0, current->thread.trap_nr, >> @@ -606,8 +608,8 @@ asmlinkage void noinstr do_fpu(struct pt_regs *regs) >> { >> irqentry_state_t state = irqentry_enter(regs); >> >> - local_irq_enable(); >> die_if_kernel("do_fpu invoked from kernel context!", regs); >> + local_irq_enable(); >> BUG_ON(is_lsx_enabled()); >> BUG_ON(is_lasx_enabled()); >> >> @@ -623,13 +625,13 @@ asmlinkage void noinstr do_lsx(struct pt_regs *regs) >> { >> irqentry_state_t state = irqentry_enter(regs); >> >> + die_if_kernel("do_lsx invoked from kernel context!", regs); >> local_irq_enable(); >> if (!cpu_has_lsx) { >> force_sig(SIGILL); >> goto out; >> } >> >> - die_if_kernel("do_lsx invoked from kernel context!", regs); >> BUG_ON(is_lasx_enabled()); >> >> preempt_disable(); >> @@ -645,14 +647,13 @@ asmlinkage void noinstr do_lasx(struct pt_regs *regs) >> { >> irqentry_state_t state = irqentry_enter(regs); >> >> + die_if_kernel("do_lasx invoked from kernel context!", regs); >> local_irq_enable(); >> if (!cpu_has_lasx) { >> force_sig(SIGILL); >> goto out; >> } >> >> - die_if_kernel("do_lasx invoked from kernel context!", regs); >> - >> preempt_disable(); >> init_restore_lasx(); >> preempt_enable(); >> @@ -666,6 +667,7 @@ asmlinkage void noinstr do_lbt(struct pt_regs *regs) >> { >> irqentry_state_t state = irqentry_enter(regs); >> >> + die_if_kernel("do_lbt invoked from kernel context!", regs); >> local_irq_enable(); >> force_sig(SIGILL); >> local_irq_disable(); >> @@ -677,7 +679,6 @@ asmlinkage void noinstr do_reserved(struct pt_regs *regs) >> { >> irqentry_state_t state = irqentry_enter(regs); >> >> - local_irq_enable(); >> /* >> * Game over - no way to handle this if it ever occurs. Most probably >> * caused by a fatal error after another hardware/software error. >> @@ -685,8 +686,8 @@ asmlinkage void noinstr do_reserved(struct pt_regs *regs) >> pr_err("Caught reserved exception %u on pid:%d [%s] - should not happen\n", >> read_csr_excode(), current->pid, current->comm); >> die_if_kernel("do_reserved exception", regs); >> + local_irq_enable(); >> force_sig(SIGUNUSED); >> - >> local_irq_disable(); >> >> irqentry_exit(regs, state); >> -- >> 2.34.3 >>
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