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SubjectRe: bcm2711_thermal: Kernel panic - not syncing: Asynchronous SError Interrupt
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[ Add Robin, Catalin and Florian in case they want to chime in ]

Hi Juerg, thanks for the report!

On Wed, 2021-02-10 at 11:48 +0100, Juerg Haefliger wrote:
> 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

So ESR's IDS (bit 24) is set, which means it's an 'Implementation Defined
SError,' hence IIUC the rest of the error code is meaningless to anyone outside
of Broadcom/RPi.

The regmap is created through the following syscon device:

avs_monitor: avs-monitor@7d5d2000 {
compatible = "brcm,bcm2711-avs-monitor",
"syscon", "simple-mfd";
reg = <0x7d5d2000 0xf00>;

thermal: thermal {
compatible = "brcm,bcm2711-thermal";
#thermal-sensor-cells = <0>;
};
};

I've done some tests with devmem, and the whole <0x7d5d2000 0xf00> range is
full of addresses that trigger this same error. Also note that as per Florian's
comments[1]: "AVS_RO_REGISTERS_0: 0x7d5d2200 - 0x7d5d22e3." But from what I can
tell, at least 0x7d5d22b0 seems to be faulty too.

Any ideas/comments? My guess is that those addresses are marked somehow as
secure, and only for VC4 to access (VC4 is RPi4's co-processor). Ultimately,
the solution is to narrow the register range exposed by avs-monitor to whatever
bcm2711-thermal needs (which is ATM a single 32bit register).

Regards,
Nicolas

[1] https://lore.kernel.org/linux-pm/82125042-684a-b4e2-fbaa-45a393b2ce5e@gmx.net/

> [ 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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