From 84b62c72faa197a5c9b75ee93527add31695fb32 Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Tue, 5 Jul 2016 15:03:59 +1000 Subject: [PATCH] powerpc: Ensure that ppc_md is empty before probing for machine type Anything in there will be overwritten, so it helps catching nasty bugs if we check that it's indeed full of NULL's before we do so. Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Michael Ellerman --- arch/powerpc/kernel/setup-common.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c index 2a3564caafd3..b8ee1c867ee3 100644 --- a/arch/powerpc/kernel/setup-common.c +++ b/arch/powerpc/kernel/setup-common.c @@ -575,6 +575,7 @@ void probe_machine(void) { extern struct machdep_calls __machine_desc_start; extern struct machdep_calls __machine_desc_end; + unsigned int i; /* * Iterate all ppc_md structures until we find the proper @@ -582,6 +583,17 @@ void probe_machine(void) */ DBG("Probing machine type ...\n"); + /* + * Check ppc_md is empty, if not we have a bug, ie, we setup an + * entry before probe_machine() which will be overwritten + */ + for (i = 0; i < (sizeof(ppc_md) / sizeof(void *)); i++) { + if (((void **)&ppc_md)[i]) { + printk(KERN_ERR "Entry %d in ppc_md non empty before" + " machine probe !\n", i); + } + } + for (machine_id = &__machine_desc_start; machine_id < &__machine_desc_end; machine_id++) {