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powerpc/pci: Fix endian bug in fixed PHB numbering 

The recent commit 63a72284b1 ("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>
This commit is contained in:
Michael Ellerman 2016-08-05 16:40:56 +10:00
parent 10560b9afc
commit 61e8a0d5a0
1 changed files with 5 additions and 2 deletions
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7
arch/powerpc/kernel/pci-common.c
View File

@ -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));