[PATCH 5.15 112/177] powerpc/85xx: Fix oops when CONFIG_FSL_PMC=n

Greg Kroah-Hartman
2021-12-20T15:13:23Z

From: Xiaoming Ni <nixiaoming@huawei.com>

[ Upstream commit 3dc709e518b47386e6af937eaec37bb36539edfd ]

When CONFIG_FSL_PMC is set to n, no value is assigned to cpu_up_prepare
in the mpc85xx_pm_ops structure. As a result, oops is triggered in
smp_85xx_start_cpu().

smp: Bringing up secondary CPUs ...
kernel tried to execute user page (0) - exploit attempt? (uid: 0)
BUG: Unable to handle kernel instruction fetch (NULL pointer?)
Faulting instruction address: 0x00000000
Oops: Kernel access of bad area, sig: 11 [#1]
...
NIP [00000000] 0x0
LR [c0021d2c] smp_85xx_kick_cpu+0xe8/0x568
Call Trace:
[c1051da8] [c0021cb8] smp_85xx_kick_cpu+0x74/0x568 (unreliable)
[c1051de8] [c0011460] __cpu_up+0xc0/0x228
[c1051e18] [c0031bbc] bringup_cpu+0x30/0x224
[c1051e48] [c0031f3c] cpu_up.constprop.0+0x180/0x33c
[c1051e88] [c00322e8] bringup_nonboot_cpus+0x88/0xc8
[c1051eb8] [c07e67bc] smp_init+0x30/0x78
[c1051ed8] [c07d9e28] kernel_init_freeable+0x118/0x2a8
[c1051f18] [c00032d8] kernel_init+0x14/0x124
[c1051f38] [c0010278] ret_from_kernel_thread+0x14/0x1c

Fixes: c45361abb918 ("powerpc/85xx: fix timebase sync issue when CONFIG_HOTPLUG_CPU=n")
Reported-by: Martin Kennedy <hurricos@gmail.com>
Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Tested-by: Martin Kennedy <hurricos@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211126041153.16926-1-nixiaoming@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/powerpc/platforms/85xx/smp.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/85xx/smp.c b/arch/powerpc/platforms/85xx/smp.c
index 83f4a6389a282..d7081e9af65c7 100644
--- a/arch/powerpc/platforms/85xx/smp.c
+++ b/arch/powerpc/platforms/85xx/smp.c
@@ -220,7 +220,7 @@ static int smp_85xx_start_cpu(int cpu)
local_irq_save(flags);
hard_irq_disable();

- if (qoriq_pm_ops)
+ if (qoriq_pm_ops && qoriq_pm_ops->cpu_up_prepare)
qoriq_pm_ops->cpu_up_prepare(cpu);

/* if cpu is not spinning, reset it */
@@ -292,7 +292,7 @@ static int smp_85xx_kick_cpu(int nr)
booting_thread_hwid = cpu_thread_in_core(nr);
primary = cpu_first_thread_sibling(nr);

- if (qoriq_pm_ops)
+ if (qoriq_pm_ops && qoriq_pm_ops->cpu_up_prepare)
qoriq_pm_ops->cpu_up_prepare(nr);

/*
--
2.34.1