[PATCH v2] riscv: fix oops caused by irq on/off tracer
Changbin Du
changbin.du at gmail.com
Thu Feb 10 19:21:35 PST 2022
On Thu, Feb 10, 2022 at 03:59:35PM +0000, Jessica Clarke wrote:
> On 10 Feb 2022, at 15:27, Jisheng Zhang <jszhang at kernel.org> wrote:
> > On Thu, Feb 10, 2022 at 09:37:58PM +0800, Changbin Du wrote:
> >> On Thu, Feb 10, 2022 at 01:32:59AM +0800, Jisheng Zhang wrote:
> >> [snip]
> >>> Hi Changbin,
> >>>
> >>> I read the code and find that current riscv frame records during
> >>> exception isn't as completed as other architectures. riscv only
> >>> records frames from the ret_from_exception(). If we add completed
> >> What do you mean for 'record'?
> >>
> >
> > stack frame record.
> >
> >>> frame records as other arch do, then the issue you saw can also
> >>> be fixed at the same time.
> >>>
> >> I don't think so. The problem is __builtin_return_address(1) trigger page fault
> >> here.
> >
> > There's misunderstanding here. I interpret this bug as incomplete
> > stackframes.
> >
> > This is current riscv stackframe during exception:
> >
> > high
> > ----------------
> > top | | <- ret_from_exception
> > ----------------
> > | | <- trace_hardirqs_on
> > -----------------
> > low
> >
> > As you said, the CALLER_ADDR1 a.k.a __builtin_return_address(1) needs
> > at least two parent call frames.
>
> No it doesn’t, you’re off by one, it only needs a valid current frame.
>
> Jess
>
yes, it is two frames not two 'parent' frames. My fault.
> > If we complete the stackframes during exception as other arch does:
> >
> > high
> > ----------------
> > top | | <- the synthetic stackframe from the interrupted point
> > ----------------
> > .....
> > ----------------
> > | | <- ret_from_exception
> > ----------------
> > | | <- trace_hardirqs_on
> > -----------------
> > low
> >
> >
> > Then we meet the "at least two parent call frames" requirement. IOW, my
> > solution solve the problem from the entry.S side. One of the advantages
> > would be we let interrupted point show up in dump_stack() as other arch
> > do. What I'm not sure is whether it's safe to do so now since rc3 is
> > released.
> >
> >>
> >>> However, I'm not sure what's the best choice now.
> >>>
> >>> A simple demo to this incomplete frames:
> >>> add dump_stack() in any ISR, then
> >>>
> >>> in riscv:
> >>> [ 2.961294] Call Trace:
> >>> [ 2.961460] [<ffffffff8000485e>] dump_backtrace+0x1c/0x24
> >>> [ 2.961823] [<ffffffff805ed980>] show_stack+0x2c/0x38
> >>> [ 2.962153] [<ffffffff805f292e>] dump_stack_lvl+0x40/0x58
> >>> [ 2.962483] [<ffffffff805f295a>] dump_stack+0x14/0x1c
> >>> [ 2.962792] [<ffffffff805f31a0>] serial8250_interrupt+0x20/0x82
> >>> [ 2.963139] [<ffffffff80053032>] __handle_irq_event_percpu+0x4c/0x106
> >>> [ 2.963526] [<ffffffff80053170>] handle_irq_event+0x38/0x80
> >>> [ 2.963856] [<ffffffff80056a32>] handle_fasteoi_irq+0x96/0x188
> >>> [ 2.964198] [<ffffffff800526ce>] generic_handle_domain_irq+0x28/0x3a
> >>> [ 2.964567] [<ffffffff802f0ae4>] plic_handle_irq+0x88/0xec
> >>> [ 2.964896] [<ffffffff800526ce>] generic_handle_domain_irq+0x28/0x3a
> >>> [ 2.965264] [<ffffffff802f08e4>] riscv_intc_irq+0x34/0x5c
> >>> [ 2.965584] [<ffffffff805f6dc8>] generic_handle_arch_irq+0x4a/0x74
> >>> [ 2.966068] [<ffffffff80002fe8>] ret_from_exception+0x0/0xc
> >>>
> >>> in x86:
> >>> [ 1.191274] Call Trace:
> >>> [ 1.192223] <IRQ>
> >>> [ 1.192758] dump_stack_lvl+0x45/0x59
> >>> [ 1.192982] serial8250_interrupt+0x24/0x88
> >>> [ 1.193105] __handle_irq_event_percpu+0x66/0x1b0
> >>> [ 1.193239] handle_irq_event+0x34/0x70
> >>> [ 1.193345] handle_edge_irq+0x85/0x1e0
> >>> [ 1.193455] __common_interrupt+0x38/0x90
> >>> [ 1.193573] common_interrupt+0x73/0x90
> >>> [ 1.193809] </IRQ>
> >>> [ 1.193889] <TASK>
> >>> [ 1.193956] asm_common_interrupt+0x1b/0x40
> >>> [ 1.194318] RIP: 0010:_raw_spin_unlock_irqrestore+0x1b/0x40
> >>> [ 1.194566] Code: 24 be 01 02 00 00 e9 54 20 bf ff 0f 1f 40 00 0f 1f
> >>> 44 00 00 f7 c6 00f
> >>> [ 1.195137] RSP: 0000:ffff888000243b68 EFLAGS: 00000246
> >>> [ 1.195314] RAX: 0000000000000000 RBX: ffffffff82025840 RCX:
> >>> 0000000000000000
> >>> [ 1.195482] RDX: 0000000000000001 RSI: 0000000000000000 RDI:
> >>> 0000000000000001
> >>> [ 1.195645] RBP: 0000000000000202 R08: ffffffffffffffff R09:
> >>> 0000000000000000
> >>> [ 1.195808] R10: 00000000000000eb R11: 0000000000000000 R12:
> >>> 0000000000000000
> >>> [ 1.195972] R13: 0000000000000040 R14: 0000000000000000 R15:
> >>> ffff888000c39000
> >>> [ 1.196245] ? _raw_spin_unlock_irqrestore+0x15/0x40
> >>> [ 1.196373] serial8250_do_startup+0x42d/0x600
> >>> [ 1.196502] uart_port_startup+0x11b/0x270
> >>> [ 1.196619] uart_port_activate+0x3f/0x60
> >>> [ 1.196729] tty_port_open+0x7e/0xd0
> >>> [ 1.196835] ? _raw_spin_unlock+0x12/0x30
> >>> [ 1.196942] uart_open+0x1a/0x30
> >>> [ 1.197036] tty_open+0x153/0x7c0
> >>> [ 1.197144] chrdev_open+0xbf/0x230
> >>> [ 1.197253] ? cdev_device_add+0x90/0x90
> >>> [ 1.197359] do_dentry_open+0x13c/0x360
> >>> [ 1.197470] path_openat+0xb0c/0xe00
> >>> [ 1.197577] ? update_load_avg+0x5f/0x640
> >>> [ 1.197691] ? finish_task_switch.isra.0+0xac/0x240
> >>> [ 1.197821] do_filp_open+0xb2/0x150
> >>> [ 1.197935] ? preempt_schedule_thunk+0x16/0x18
> >>> [ 1.198049] ? preempt_schedule_common+0x90/0xd0
> >>> [ 1.198167] ? preempt_schedule_thunk+0x16/0x18
> >>> [ 1.198291] file_open_name+0xf1/0x1b0
> >>> [ 1.198397] filp_open+0x2c/0x50
> >>> [ 1.198495] console_on_rootfs+0x19/0x52
> >>> [ 1.198648] kernel_init_freeable+0x19a/0x1c7
> >>> [ 1.198765] ? rest_init+0xc0/0xc0
> >>> [ 1.198867] kernel_init+0x16/0x110
> >>> [ 1.198965] ret_from_fork+0x1f/0x30
> >>> [ 1.199131] </TASK>
> >>>
> >> As I said before, this issue is not related to stackdump.
> >>
> >> Besides, you can see more calltrace on x86 that because x86 iterate all stacks
> >> (kernel, irq or exception) when dumping stacktrace. While RISCV only show
> >> calltrace of current stack.
> >>
> >
> > I'm not sure whether there's misunderstanding. See above.
> >
> > Thanks
> >
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv at lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv
>
--
Cheers,
Changbin Du
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