Since the CPU is generating an exception when accessing unaligned word, and
as this exception is not yet handled when running prom_init, data should be
copied from the architecture vector byte per byte.
Signed-off-by: Laurent Dufour <lduf...@linux.vnet.ibm.com>
---
arch/powerpc/kernel/prom_init.c | 28 ++++++++++++++++++++++------
1 file changed, 22 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index edcb6be..50065ee 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -855,7 +855,8 @@ static void __init prom_send_capabilities(void)
{
ihandle root;
prom_arg_t ret;
- __be32 *cores;
+ u32 cores;
+ unsigned char *ptcores;
root = call_prom("open", 1, 1, ADDR("/"));
if (root != 0) {
@@ -865,15 +866,30 @@ static void __init prom_send_capabilities(void)
* (we assume this is the same for all cores) and use it to
* divide NR_CPUS.
*/
- cores = (__be32
*)&ibm_architecture_vec[IBM_ARCH_VEC_NRCORES_OFFSET];
- if (be32_to_cpup(cores) != NR_CPUS) {
+
+ /* The core value may start at an odd address. If such a word
+ * access is made at a cache line boundary, this leads to an
+ * exception which may not be handled at this time.
+ * Forcing a per byte access to avoid exception.
+ */
+ ptcores = &ibm_architecture_vec[IBM_ARCH_VEC_NRCORES_OFFSET];
+ cores = 0;
+ cores |= ptcores[0] << 24;
+ cores |= ptcores[1] << 16;
+ cores |= ptcores[2] << 8;
+ cores |= ptcores[3];
+ if (cores != NR_CPUS) {
prom_printf("WARNING ! "
"ibm_architecture_vec structure
inconsistent: %lu!\n",
- be32_to_cpup(cores));
+ cores);
} else {
- *cores = cpu_to_be32(DIV_ROUND_UP(NR_CPUS,
prom_count_smt_threads()));
+ cores = DIV_ROUND_UP(NR_CPUS, prom_count_smt_threads());
prom_printf("Max number of cores passed to firmware:
%lu (NR_CPUS = %lu)\n",
- be32_to_cpup(cores), NR_CPUS);
+ cores, NR_CPUS);
+ ptcores[0] = (cores >> 24) & 0xff;
+ ptcores[1] = (cores >> 16) & 0xff;
+ ptcores[2] = (cores >> 8) & 0xff;
+ ptcores[3] = cores & 0xff;
}
/* try calling the ibm,client-architecture-support method */
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