Re: [PATCH] riscv: Trace irq on only interrupt is enabled

[Palmer Dabbelt]

On Fri, 18 Dec 2020 16:20:51 PST (-0800), Atish Patra wrote:
> We should call irq trace only if interrupt is going to be enabled during
> excecption handling. Otherwise, it results in following warning during
> boot with lock debugging enabled.
>
> [    0.000000] ------------[ cut here ]------------
> [    0.000000] DEBUG_LOCKS_WARN_ON(early_boot_irqs_disabled)
> [    0.000000] WARNING: CPU: 0 PID: 0 at kernel/locking/lockdep.c:4085 lockdep_hardirqs_on_prepare+0x22a/0x22e
> [    0.000000] Modules linked in:
> [    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 5.10.0-00022-ge20097fb37e2-dirty #548
> [    0.000000] epc: c005d5d4 ra : c005d5d4 sp : c1c01e80
> [    0.000000]  gp : c1d456e0 tp : c1c0a980 t0 : 00000000
> [    0.000000]  t1 : ffffffff t2 : 00000000 s0 : c1c01ea0
> [    0.000000]  s1 : c100f360 a0 : 0000002d a1 : c00666ee
> [    0.000000]  a2 : 00000000 a3 : 00000000 a4 : 00000000
> [    0.000000]  a5 : 00000000 a6 : c1c6b390 a7 : 3ffff00e
> [    0.000000]  s2 : c2384fe8 s3 : 00000000 s4 : 00000001
> [    0.000000]  s5 : c1c0a980 s6 : c1d48000 s7 : c1613b4c
> [    0.000000]  s8 : 00000fff s9 : 80000200 s10: c1613b40
> [    0.000000]  s11: 00000000 t3 : 00000000 t4 : 00000000
> [    0.000000]  t5 : 00000001 t6 : 00000000
>
> Fixes: 3c4697982982 ("riscv:Enable LOCKDEP_SUPPORT & fixup TRACE_IRQFLAGS_SUPPORT")
> Cc: stable@xxxxxxxxxxxxxxx
>
> Signed-off-by: Atish Patra <atish.patra@xxxxxxx>
> ---
>  arch/riscv/kernel/entry.S | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
> index 524d918f3601..7dea5ee5a3ac 100644
> --- a/arch/riscv/kernel/entry.S
> +++ b/arch/riscv/kernel/entry.S
> @@ -124,15 +124,15 @@ skip_context_tracking:
>  	REG_L a1, (a1)
>  	jr a1
>  1:
> -#ifdef CONFIG_TRACE_IRQFLAGS
> -	call trace_hardirqs_on
> -#endif
>  	/*
>  	 * Exceptions run with interrupts enabled or disabled depending on the
>  	 * state of SR_PIE in m/sstatus.
>  	 */
>  	andi t0, s1, SR_PIE
>  	beqz t0, 1f
> +#ifdef CONFIG_TRACE_IRQFLAGS
> +	call trace_hardirqs_on
> +#endif
>  	csrs CSR_STATUS, SR_IE
>
>  1:

Thanks, this is on fixes.