Re: [PATCH v2] of: unittest: Disable interrupt node tests for old world MAC systems

[Frank Rowand]

On 09/25/18 21:06, Guenter Roeck wrote:
> On systems with OF_IMAP_OLDWORLD_MAC set in of_irq_workarounds, the
> devicetree interrupt parsing code is different, causing unit tests of
> devicetree interrupt nodes to fail. Due to a bug in unittest code, which
> tries to dereference an uninitialized pointer, this results in a crash.
> 
> OF: /testcase-data/phandle-tests/consumer-a: arguments longer than property
> Unable to handle kernel paging request for data at address 0x00bc616e
> Faulting instruction address: 0xc08e9468
> Oops: Kernel access of bad area, sig: 11 [#1]
> BE PREEMPT PowerMac
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper Not tainted 4.14.72-rc1-yocto-standard+ #1
> task: cf8e0000 task.stack: cf8da000
> NIP:  c08e9468 LR: c08ea5bc CTR: c08ea5ac
> REGS: cf8dbb50 TRAP: 0300   Not tainted  (4.14.72-rc1-yocto-standard+)
> MSR:  00001032 <ME,IR,DR,RI>  CR: 82004044  XER: 00000000
> DAR: 00bc616e DSISR: 40000000
> GPR00: c08ea5bc cf8dbc00 cf8e0000 c13ca517 c13ca517 c13ca8a0 00000066 00000002
> GPR08: 00000063 00bc614e c0b05865 000affff 82004048 00000000 c00047f0 00000000
> GPR16: c0a80000 c0a9cc34 c13ca517 c0ad1134 05ffffff 000affff c0b05860 c0abeef8
> GPR24: cecec278 cecec278 c0a8c4d0 c0a885e0 c13ca8a0 05ffffff c13ca8a0 c13ca517
> 
> NIP [c08e9468] device_node_gen_full_name+0x30/0x15c
> LR [c08ea5bc] device_node_string+0x190/0x3c8
> Call Trace:
> [cf8dbc00] [c007f670] trace_hardirqs_on_caller+0x118/0x1fc (unreliable)
> [cf8dbc40] [c08ea5bc] device_node_string+0x190/0x3c8
> [cf8dbcb0] [c08eb794] pointer+0x25c/0x4d0
> [cf8dbd00] [c08ebcbc] vsnprintf+0x2b4/0x5ec
> [cf8dbd60] [c08ec00c] vscnprintf+0x18/0x48
> [cf8dbd70] [c008e268] vprintk_store+0x4c/0x22c
> [cf8dbda0] [c008ecac] vprintk_emit+0x94/0x130
> [cf8dbdd0] [c008ff54] printk+0x5c/0x6c
> [cf8dbe10] [c0b8ddd4] of_unittest+0x2220/0x26f8
> [cf8dbea0] [c0004434] do_one_initcall+0x4c/0x184
> [cf8dbf00] [c0b4534c] kernel_init_freeable+0x13c/0x1d8
> [cf8dbf30] [c0004814] kernel_init+0x24/0x118
> [cf8dbf40] [c0013398] ret_from_kernel_thread+0x5c/0x64
> 
> The problem was observed when running a qemu test for the g3beige machine
> with devicetree unittests enabled.
> 
> Disable interrupt node tests on affected systems to avoid both false
> unittest failures and the crash.
> 
> With this patch in place, unittest on the affected system passes with
> the following message.
> 
> 	dt-test ### end of unittest - 144 passed, 0 failed
> 
> Fixes: 53a42093d96ef ("of: Add device tree selftests")
> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
> v2: Do not use goto to skip tests.
>     Provide test log in commit message.
> 
>  drivers/of/unittest.c | 26 ++++++++++++++++++--------
>  1 file changed, 18 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
> index 722537e14848..41b49716ac75 100644
> --- a/drivers/of/unittest.c
> +++ b/drivers/of/unittest.c
> @@ -771,6 +771,9 @@ static void __init of_unittest_parse_interrupts(void)
>  	struct of_phandle_args args;
>  	int i, rc;
>  
> +	if (of_irq_workarounds & OF_IMAP_OLDWORLD_MAC)
> +		return;
> +
>  	np = of_find_node_by_path("/testcase-data/interrupts/interrupts0");
>  	if (!np) {
>  		pr_err("missing testcase data\n");
> @@ -845,6 +848,9 @@ static void __init of_unittest_parse_interrupts_extended(void)
>  	struct of_phandle_args args;
>  	int i, rc;
>  
> +	if (of_irq_workarounds & OF_IMAP_OLDWORLD_MAC)
> +		return;
> +
>  	np = of_find_node_by_path("/testcase-data/interrupts/interrupts-extended0");
>  	if (!np) {
>  		pr_err("missing testcase data\n");
> @@ -1001,15 +1007,19 @@ static void __init of_unittest_platform_populate(void)
>  	pdev = of_find_device_by_node(np);
>  	unittest(pdev, "device 1 creation failed\n");
>  
> -	irq = platform_get_irq(pdev, 0);
> -	unittest(irq == -EPROBE_DEFER, "device deferred probe failed - %d\n", irq);
> +	if (!(of_irq_workarounds & OF_IMAP_OLDWORLD_MAC)) {
> +		irq = platform_get_irq(pdev, 0);
> +		unittest(irq == -EPROBE_DEFER,
> +			 "device deferred probe failed - %d\n", irq);
>  
> -	/* Test that a parsing failure does not return -EPROBE_DEFER */
> -	np = of_find_node_by_path("/testcase-data/testcase-device2");
> -	pdev = of_find_device_by_node(np);
> -	unittest(pdev, "device 2 creation failed\n");
> -	irq = platform_get_irq(pdev, 0);
> -	unittest(irq < 0 && irq != -EPROBE_DEFER, "device parsing error failed - %d\n", irq);
> +		/* Test that a parsing failure does not return -EPROBE_DEFER */
> +		np = of_find_node_by_path("/testcase-data/testcase-device2");
> +		pdev = of_find_device_by_node(np);
> +		unittest(pdev, "device 2 creation failed\n");
> +		irq = platform_get_irq(pdev, 0);
> +		unittest(irq < 0 && irq != -EPROBE_DEFER,
> +			 "device parsing error failed - %d\n", irq);
> +	}
>  
>  	np = of_find_node_by_path("/testcase-data/platform-tests");
>  	unittest(np, "No testcase data in device tree\n");
> 

Thank you Guenter.

Reviewed-by: Frank Rowand <frank.rowand@xxxxxxxx>