arm/fdt.c: Don't generate the node if generator function is NULL

Print a more helpful debugging message when a MMIO device hasn't set a
function to generate an FDT node instead of causing a segmentation fault by
dereferencing a NULL pointer.

Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Link: https://lore.kernel.org/r/20210713170631.155595-3-alexandru.elisei@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

1 files changed, 6 insertions, 1 deletions

diff --git a/arm/fdt.c b/arm/fdt.c
index 02091e9e..7032985e 100644
--- a/arm/fdt.c
+++ b/arm/fdt.c
@@ -171,7 +171,12 @@ static int setup_fdt(struct kvm *kvm)
 	dev_hdr = device__first_dev(DEVICE_BUS_MMIO);
 	while (dev_hdr) {
 		generate_mmio_fdt_nodes = dev_hdr->data;
-		generate_mmio_fdt_nodes(fdt, dev_hdr, generate_irq_prop);
+		if (generate_mmio_fdt_nodes) {
+			generate_mmio_fdt_nodes(fdt, dev_hdr, generate_irq_prop);
+		} else {
+			pr_debug("Missing FDT node generator for MMIO device %d",
+				 dev_hdr->dev_num);
+		}
 		dev_hdr = device__next_dev(dev_hdr);
 	}