bcm2711_thermal: Kernel panic - not syncing: Asynchronous SError Interrupt

[Juerg Haefliger]

Trying to dump the BCM2711 registers kills the kernel:

# cat /sys/kernel/debug/regmap/dummy-avs-monitor\@fd5d2000/range
0-efc
# cat /sys/kernel/debug/regmap/dummy-avs-monitor\@fd5d2000/registers 

[   62.857661] SError Interrupt on CPU1, code 0xbf000002 -- SError
[   62.857671] CPU: 1 PID: 478 Comm: cat Not tainted 5.11.0-rc7 #4
[   62.857674] Hardware name: Raspberry Pi 4 Model B Rev 1.2 (DT)
[   62.857676] pstate: 20000085 (nzCv daIf -PAN -UAO -TCO BTYPE=--)
[   62.857679] pc : regmap_mmio_read32le+0x1c/0x34
[   62.857681] lr : regmap_mmio_read+0x50/0x80
[   62.857682] sp : ffff8000105c3c00
[   62.857685] x29: ffff8000105c3c00 x28: 0000000000000014 
[   62.857694] x27: 0000000000000014 x26: ffffd2ea1c2060b0 
[   62.857699] x25: ffff4e34408ecc00 x24: 0000000000000efc 
[   62.857704] x23: ffff8000105c3e20 x22: ffff8000105c3d3c 
[   62.857710] x21: ffff8000105c3d3c x20: 0000000000000014 
[   62.857715] x19: ffff4e344037a900 x18: 0000000000000020 
[   62.857720] x17: 0000000000000000 x16: 0000000000000000 
[   62.857725] x15: ffff4e3447ac40f0 x14: 0000000000000003 
[   62.857730] x13: ffff4e34422c0000 x12: ffff4e34422a0046 
[   62.857735] x11: ffffd2ea1c8765e0 x10: 0000000000000000 
[   62.857741] x9 : ffffd2ea1b9495a0 x8 : ffff4e34429ef980 
[   62.857746] x7 : 000000000000000f x6 : ffff4e34422a004b 
[   62.857751] x5 : 00000000fffffff9 x4 : 0000000000000000 
[   62.857757] x3 : ffffd2ea1b949550 x2 : ffffd2ea1b949330 
[   62.857761] x1 : 0000000000000014 x0 : 0000000000000000 
[   62.857767] Kernel panic - not syncing: Asynchronous SError Interrupt
[   62.857770] CPU: 1 PID: 478 Comm: cat Not tainted 5.11.0-rc7 #4
[   62.857773] Hardware name: Raspberry Pi 4 Model B Rev 1.2 (DT)
[   62.857775] Call trace:
[   62.857777]  dump_backtrace+0x0/0x1e0
[   62.857778]  show_stack+0x24/0x70
[   62.857780]  dump_stack+0xd0/0x12c
[   62.857782]  panic+0x168/0x370
[   62.857783]  nmi_panic+0x98/0xa0
[   62.857786]  arm64_serror_panic+0x8c/0x98
[   62.857787]  do_serror+0x3c/0x6c
[   62.857789]  el1_error+0x78/0xf0
[   62.857791]  regmap_mmio_read32le+0x1c/0x34
[   62.857793]  _regmap_bus_reg_read+0x24/0x30
[   62.857795]  _regmap_read+0x6c/0x17c
[   62.857797]  regmap_read+0x58/0x84
[   62.857799]  regmap_read_debugfs+0x138/0x3f4
[   62.857801]  regmap_map_read_file+0x34/0x40
[   62.857803]  full_proxy_read+0x6c/0xc0
[   62.857805]  vfs_read+0xb8/0x1e4
[   62.857807]  ksys_read+0x78/0x10c
[   62.857809]  __arm64_sys_read+0x28/0x34
[   62.857811]  el0_svc_common.constprop.0+0x7c/0x194
[   62.857813]  do_el0_svc+0x30/0x9c
[   62.857814]  el0_svc+0x20/0x30
[   62.857816]  el0_sync_handler+0x1a4/0x1b0
[   62.857818]  el0_sync+0x174/0x180
[   62.857842] SMP: stopping secondary CPUs
[   62.857845] Kernel Offset: 0x52ea0b080000 from 0xffff800010000000
[   62.857847] PHYS_OFFSET: 0xffffb1cc00000000
[   62.857849] CPU features: 0x00240022,61806000
[   62.857851] Memory Limit: none

Sprinkling printks around regmap_read [1] shows that reading from 0x14 (20)
seems to cause the issue:


[   40.456230] map=ffff020a069c9c00, from=0, to=3836, count=131072
[   40.462520] map=ffff020a069c9c00, i=0
[   40.466319] ret=0, val=0
[   40.468922] map=ffff020a069c9c00, i=4
[   40.472684] ret=0, val=0
[   40.475292] map=ffff020a069c9c00, i=8
[   40.479048] ret=0, val=0
[   40.481649] map=ffff020a069c9c00, i=12
[   40.485492] ret=0, val=0
[   40.488080] map=ffff020a069c9c00, i=16
[   40.491922] ret=0, val=0
[   40.494523] map=ffff020a069c9c00, i=20
[   40.498497] SError Interrupt on CPU0, code 0xbf000002 -- SError
[   40.498499] CPU: 0 PID: 486 Comm: cat Not tainted 5.11.0-rc7+ #8
[   40.498501] Hardware name: Raspberry Pi 4 Model B Rev 1.2 (DT)


...Juerg

[1]
diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index ff2ee87987c7..9465f5a2f3b8 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -229,6 +229,7 @@ static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
        if (count > (PAGE_SIZE << (MAX_ORDER - 1)))
                count = PAGE_SIZE << (MAX_ORDER - 1);
 
+       printk("map=%px, from=%d, to=%d, count=%ld\n", map, from, to, count);
        buf = kmalloc(count, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;
@@ -253,7 +254,9 @@ static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
                        buf_pos += map->debugfs_reg_len + 2;
 
                        /* Format the value, write all X if we can't read */
+                       printk("map=%px, i=%d\n", map, i);
                        ret = regmap_read(map, i, &val);
+                       printk("ret=%ld, val=%x\n", ret, val);
                        if (ret == 0)
                                snprintf(buf + buf_pos, count - buf_pos,
                                         "%.*x", map->debugfs_val_len, val);

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