powerpc/pci: Fix endian bug in fixed PHB numbering
The recent commit63a72284b1
("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:63a72284b1
("powerpc/pci: Assign fixed PHB number based on device-tree properties") Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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@ -78,6 +78,7 @@ EXPORT_SYMBOL(get_pci_dma_ops);
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static int get_phb_number(struct device_node *dn)
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{
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int ret, phb_id = -1;
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u32 prop_32;
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u64 prop;
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/*
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@ -86,8 +87,10 @@ static int get_phb_number(struct device_node *dn)
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* reading "ibm,opal-phbid", only present in OPAL environment.
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*/
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ret = of_property_read_u64(dn, "ibm,opal-phbid", &prop);
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if (ret)
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ret = of_property_read_u32_index(dn, "reg", 1, (u32 *)&prop);
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if (ret) {
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ret = of_property_read_u32_index(dn, "reg", 1, &prop_32);
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prop = prop_32;
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}
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if (!ret)
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phb_id = (int)(prop & (MAX_PHBS - 1));
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