[PATCH 1/1] arm64: kexec: no need to do irq_chip->irq_mask if it already masked

From: Jason Liu
Date: Thu Jul 02 2020 - 05:32:03 EST


No need to do the irq_chip->irq_mask() if it already masked.
BTW, unconditionally do the irq_chip->irq_mask() will also bring issues
when the irq_chip in the runtime PM suspend. Accessing registers of the
irq_chip will bring in the exceptions. For example on the i.MX:

root@imx8qmmek:~# echo c > /proc/sysrq-trigger
[ 177.796182] sysrq: Trigger a crash
[ 177.799596] Kernel panic - not syncing: sysrq triggered crash
[ 177.875616] SMP: stopping secondary CPUs
[ 177.891936] Internal error: synchronous external abort: 96000210 [#1] PREEMPT SMP
[ 177.899429] Modules linked in: crct10dif_ce mxc_jpeg_encdec
[ 177.905018] CPU: 1 PID: 944 Comm: sh Kdump: loaded Not tainted
[ 177.913457] Hardware name: Freescale i.MX8QM MEK (DT)
[ 177.918517] pstate: a0000085 (NzCv daIf -PAN -UAO)
[ 177.923318] pc : imx_irqsteer_irq_mask+0x50/0x80
[ 177.927944] lr : imx_irqsteer_irq_mask+0x38/0x80
[ 177.932561] sp : ffff800011fe3a50
[ 177.935880] x29: ffff800011fe3a50 x28: ffff0008f7708e00
[ 177.941196] x27: 0000000000000000 x26: 0000000000000000
[ 177.946513] x25: ffff800011a30c80 x24: 0000000000000000
[ 177.951830] x23: ffff800011fe3af8 x22: ffff0008f24469d4
[ 177.957147] x21: ffff0008f2446880 x20: ffff0008f25f5658
[ 177.962463] x19: ffff800012611004 x18: 0000000000000001
[ 177.967780] x17: 0000000000000000 x16: 0000000000000000
[ 177.973097] x15: ffff0008f7709270 x14: 0000000060000085
[ 177.978414] x13: ffff800010177570 x12: ffff800011fe3ab0
[ 177.983730] x11: ffff80001017749c x10: 0000000000000040
[ 177.989047] x9 : ffff8000119f1c80 x8 : ffff8000119f1c78
[ 177.994364] x7 : ffff0008f46bedf8 x6 : 0000000000000000
[ 177.999681] x5 : ffff0008f46beda0 x4 : 0000000000000000
[ 178.004997] x3 : ffff0008f24469d4 x2 : ffff800012611000
[ 178.010314] x1 : 0000000000000080 x0 : 0000000000000080
[ 178.015630] Call trace:
[ 178.018077] imx_irqsteer_irq_mask+0x50/0x80
[ 178.022352] machine_crash_shutdown+0xa8/0x100
[ 178.026802] __crash_kexec+0x6c/0x118
[ 178.030464] panic+0x19c/0x324
[ 178.033524] sysrq_handle_reboot+0x0/0x20
[ 178.037537] __handle_sysrq+0x88/0x180
[ 178.041290] write_sysrq_trigger+0x8c/0xb0
[ 178.045389] proc_reg_write+0x78/0xb0
[ 178.049055] __vfs_write+0x18/0x40
[ 178.052461] vfs_write+0xdc/0x1c8
[ 178.055779] ksys_write+0x68/0xf0
[ 178.059098] __arm64_sys_write+0x18/0x20
[ 178.063027] el0_svc_common.constprop.0+0x68/0x160
[ 178.067821] el0_svc_handler+0x20/0x80
[ 178.071573] el0_svc+0x8/0xc
[ 178.074463] Code: 93407e73 91001273 aa0003e1 8b130053 (b9400260)
[ 178.080567] ---[ end trace 652333f6c6d6b05d ]---

Signed-off-by: Jason Liu <jason.hui.liu@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/arm64/kernel/machine_kexec.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
index a0b144cfaea7..8ab263c733bf 100644
--- a/arch/arm64/kernel/machine_kexec.c
+++ b/arch/arm64/kernel/machine_kexec.c
@@ -236,7 +236,7 @@ static void machine_kexec_mask_interrupts(void)
chip->irq_eoi)
chip->irq_eoi(&desc->irq_data);

- if (chip->irq_mask)
+ if (chip->irq_mask && !irqd_irq_masked(&desc->irq_data))
chip->irq_mask(&desc->irq_data);

if (chip->irq_disable && !irqd_irq_disabled(&desc->irq_data))
--
2.27.0