From 61e8a0d5a0270b91581f6c715036844b2ea98da1 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Fri, 5 Aug 2016 16:40:56 +1000 Subject: [PATCH] powerpc/pci: Fix endian bug in fixed PHB numbering The recent commit 63a72284b159 ("powerpc/pci: Assign fixed PHB number based on device-tree properties"), added code to read a 64-bit property from the device tree, and if not found read a 32-bit property (reg). There was a bug in the 32-bit case, on big endian machines, due to the use of the 64-bit value to read the 32-bit property. The cast of &prop means we end up writing to the high 32-bit of prop, leaving the low 32-bits containing whatever junk was on the stack. If that junk value was non-zero, and < MAX_PHBS, we would end up using it as the PHB id. This results in users seeing what appear to be random PHB ids. Fix it by reading into a u32 property and then assigning that to the u64 value, letting the CPU do the correct conversions for us. Fixes: 63a72284b159 ("powerpc/pci: Assign fixed PHB number based on device-tree properties") Signed-off-by: Michael Ellerman --- arch/powerpc/kernel/pci-common.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c index a5c0153ede37..7fdf324d5b51 100644 --- a/arch/powerpc/kernel/pci-common.c +++ b/arch/powerpc/kernel/pci-common.c @@ -78,6 +78,7 @@ EXPORT_SYMBOL(get_pci_dma_ops); static int get_phb_number(struct device_node *dn) { int ret, phb_id = -1; + u32 prop_32; u64 prop; /* @@ -86,8 +87,10 @@ static int get_phb_number(struct device_node *dn) * reading "ibm,opal-phbid", only present in OPAL environment. */ ret = of_property_read_u64(dn, "ibm,opal-phbid", &prop); - if (ret) - ret = of_property_read_u32_index(dn, "reg", 1, (u32 *)&prop); + if (ret) { + ret = of_property_read_u32_index(dn, "reg", 1, &prop_32); + prop = prop_32; + } if (!ret) phb_id = (int)(prop & (MAX_PHBS - 1)); -- 2.20.1