Messages in this thread | | | Subject | Re: [PATCH] LoongArch: Fix irq enable in exception handlers | From | Jinyang He <> | Date | Tue, 27 Dec 2022 18:10:56 +0800 |
| |
On 2022-12-27 17:52, Huacai Chen wrote:
> On Tue, Dec 27, 2022 at 5:30 PM Jinyang He <hejinyang@loongson.cn> wrote: >> >> 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. > die_if_kernel is called with irq enabled in old kernels for several > years, and has no problems.
I think because it never call die() in die_if_kernel(). What I do emphasize is that there needs to be more strict logic here than it worked well in the past. I bet if die_if_kernel() was removed, it will still work well in the future.
> >> >>> 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? > You can ask Huqi for more details, and this was discussed publicly last week.
To: Qi Hu
Hi,
We really need some help. Can you give us some ideas?
Thanks,
Jinyang
> Huacai >> >> 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 >>>> >>
| |