[PATCH] Fix CPU boot problem

From: Dave Hansen <haveblue@us.ibm.com>

Hmmm.  This is looking like fallout from the massive wli-bomb.  Here's
the loop that controls the cpu booting, before and after cpumask_t:

-	for (bit = 0; kicked < NR_CPUS && bit < BITS_PER_LONG; bit++)
+	for (bit = 0; kicked < NR_CPUS && bit < MAX_APICS; bit++)
		apicid = cpu_present_to_apicid(bit);

"kicked" only gets incremented for CPUs that were successfully booted,
so it doesn't help terminate the loop much.  MAX_APICS is 256 on summit,
which is *MUCH* bigger than BITS_PER_LONG.
cpu_2_logical_apicid[NR_CPUS] which is referenced from
cpu_present_to_apicid() is getting referenced up to MAX_APICs, which is
bigger than NR_CPUS.  Overflow.  Bang.  garbage != BAD_APICID :)

4 files changed, 8 insertions, 0 deletions

diff --git a/include/asm-i386/mach-bigsmp/mach_apic.h b/include/asm-i386/mach-bigsmp/mach_apic.h
index a63520b95a36..c21ed08175d5 100644
--- a/include/asm-i386/mach-bigsmp/mach_apic.h
+++ b/include/asm-i386/mach-bigsmp/mach_apic.h
@@ -98,6 +98,8 @@ extern u8 cpu_2_logical_apicid[];
 /* Mapping from cpu number to logical apicid */
 static inline int cpu_to_logical_apicid(int cpu)
 {
+       if (cpu >= NR_CPUS)
+	       return BAD_APICID;
        return (int)cpu_2_logical_apicid[cpu];
  }
 
diff --git a/include/asm-i386/mach-es7000/mach_apic.h b/include/asm-i386/mach-es7000/mach_apic.h
index f83d03b0458f..aa7fd107c1c9 100644
--- a/include/asm-i386/mach-es7000/mach_apic.h
+++ b/include/asm-i386/mach-es7000/mach_apic.h
@@ -123,6 +123,8 @@ extern u8 cpu_2_logical_apicid[];
 /* Mapping from cpu number to logical apicid */
 static inline int cpu_to_logical_apicid(int cpu)
 {
+       if (cpu >= NR_CPUS)
+	       return BAD_APICID;
        return (int)cpu_2_logical_apicid[cpu];
 }
 
diff --git a/include/asm-i386/mach-numaq/mach_apic.h b/include/asm-i386/mach-numaq/mach_apic.h
index ceca92723c0e..2f9f19237460 100644
--- a/include/asm-i386/mach-numaq/mach_apic.h
+++ b/include/asm-i386/mach-numaq/mach_apic.h
@@ -60,6 +60,8 @@ static inline physid_mask_t ioapic_phys_id_map(physid_mask_t phys_map)
 extern u8 cpu_2_logical_apicid[];
 static inline int cpu_to_logical_apicid(int cpu)
 {
+       if (cpu >= NR_CPUS)
+	       return BAD_APICID;
 	return (int)cpu_2_logical_apicid[cpu];
 }
 
diff --git a/include/asm-i386/mach-summit/mach_apic.h b/include/asm-i386/mach-summit/mach_apic.h
index 2247c7adca3d..f79d5df55e1a 100644
--- a/include/asm-i386/mach-summit/mach_apic.h
+++ b/include/asm-i386/mach-summit/mach_apic.h
@@ -80,6 +80,8 @@ static inline int apicid_to_node(int logical_apicid)
 extern u8 cpu_2_logical_apicid[];
 static inline int cpu_to_logical_apicid(int cpu)
 {
+       if (cpu >= NR_CPUS)
+	       return BAD_APICID;
 	return (int)cpu_2_logical_apicid[cpu];
 }