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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2014-03-28 13:36:29 +1100
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2014-04-07 10:33:15 +1000
commita944a9c40b81a71609692c4909bb57e1d01f4bb7 (patch)
tree88bf4fbfa126ba8c66cf315d34f04913b6e05260 /arch/powerpc
parent7222f779acf94a123557c7bbbfbcc19424589f52 (diff)
powerpc/ppc64: Gracefully handle early interrupts
If we take an interrupt such as a trap caused by a BUG_ON before the MMU has been setup, the interrupt handlers try to enable virutal mode and cause a recursive crash, making the original problem very hard to debug. This fixes it by adjusting the "kernel_msr" value in the PACA so that it only has MSR_IR and MSR_DR (translation for instruction and data) set after the MMU has been initialized for the processor. We may still not have a console yet but at least we don't get into a recursive fault (and early debug console or memory dump via JTAG of the kernel buffer *will* give us the proper error). Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/kernel/paca.c3
-rw-r--r--arch/powerpc/kernel/setup_64.c15
2 files changed, 17 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/paca.c b/arch/powerpc/kernel/paca.c
index bf0aada02fe..ad302f845e5 100644
--- a/arch/powerpc/kernel/paca.c
+++ b/arch/powerpc/kernel/paca.c
@@ -152,7 +152,8 @@ void __init initialise_paca(struct paca_struct *new_paca, int cpu)
new_paca->paca_index = cpu;
new_paca->kernel_toc = kernel_toc;
new_paca->kernelbase = (unsigned long) _stext;
- new_paca->kernel_msr = MSR_KERNEL;
+ /* Only set MSR:IR/DR when MMU is initialized */
+ new_paca->kernel_msr = MSR_KERNEL & ~(MSR_IR | MSR_DR);
new_paca->hw_cpu_id = 0xffff;
new_paca->kexec_state = KEXEC_STATE_NONE;
new_paca->__current = &init_task;
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index d8aabbdc648..1d33e817ab2 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -261,6 +261,14 @@ void __init early_setup(unsigned long dt_ptr)
/* Initialize the hash table or TLB handling */
early_init_mmu();
+ /*
+ * At this point, we can let interrupts switch to virtual mode
+ * (the MMU has been setup), so adjust the MSR in the PACA to
+ * have IR and DR set.
+ */
+ get_paca()->kernel_msr = MSR_KERNEL;
+
+ /* Reserve large chunks of memory for use by CMA for KVM */
kvm_cma_reserve();
/*
@@ -293,6 +301,13 @@ void early_setup_secondary(void)
/* Initialize the hash table or TLB handling */
early_init_mmu_secondary();
+
+ /*
+ * At this point, we can let interrupts switch to virtual mode
+ * (the MMU has been setup), so adjust the MSR in the PACA to
+ * have IR and DR set.
+ */
+ get_paca()->kernel_msr = MSR_KERNEL;
}
#endif /* CONFIG_SMP */