Date:   Tue, 25 Sep 2018 10:32:43 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Rob Herring <robh+dt@...nel.org>
Cc:     Frank Rowand <frowand.list@...il.com>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH] of: unittest: Disable interrupt node tests for old world MAC systems

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.

Fixes: 53a42093d96ef ("of: Add device tree selftests")
Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
The changes in of_unittest_platform_populate() are kept at the minimum;
I wanted to avoid changing the intendation.
An alternative fix might be to move the interrupt tests to a separate
function.

 drivers/of/unittest.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
index 722537e14848..bd1d56cf1962 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");
@@ -1001,6 +1007,9 @@ static void __init of_unittest_platform_populate(void)
 	pdev = of_find_device_by_node(np);
 	unittest(pdev, "device 1 creation failed\n");
 
+	if (of_irq_workarounds & OF_IMAP_OLDWORLD_MAC)
+		goto skip_irqtests;
+
 	irq = platform_get_irq(pdev, 0);
 	unittest(irq == -EPROBE_DEFER, "device deferred probe failed - %d\n", irq);
 
@@ -1011,6 +1020,7 @@ static void __init of_unittest_platform_populate(void)
 	irq = platform_get_irq(pdev, 0);
 	unittest(irq < 0 && irq != -EPROBE_DEFER, "device parsing error failed - %d\n", irq);
 
+skip_irqtests:
 	np = of_find_node_by_path("/testcase-data/platform-tests");
 	unittest(np, "No testcase data in device tree\n");
 	if (!np)
-- 
2.7.4

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