ARM: 7807/1: kexec: validate CPU hotplug support

[karo-tx-linux.git] / arch / arm / kernel / machine_kexec.c

diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c
index 4fb074c446bf901df288b3878341a169dacb843b..d7c82df692436df0248fa1a00502cf74b7fca23c 100644 (file)
--- a/arch/arm/kernel/machine_kexec.c
+++ b/arch/arm/kernel/machine_kexec.c
@@ -15,6 +15,7 @@
 #include <asm/mmu_context.h>
 #include <asm/cacheflush.h>
 #include <asm/mach-types.h>
+#include <asm/smp_plat.h>
 #include <asm/system_misc.h>
 
 extern const unsigned char relocate_new_kernel[];
@@ -38,6 +39,14 @@ int machine_kexec_prepare(struct kimage *image)
        __be32 header;
        int i, err;
 
+       /*
+        * Validate that if the current HW supports SMP, then the SW supports
+        * and implements CPU hotplug for the current HW. If not, we won't be
+        * able to kexec reliably, so fail the prepare operation.
+        */
+       if (num_possible_cpus() > 1 && !platform_can_cpu_hotplug())
+               return -EINVAL;
+
        /*
         * No segment at default ATAGs address. try to locate
         * a dtb using magic.
@@ -134,10 +143,13 @@ void machine_kexec(struct kimage *image)
        unsigned long reboot_code_buffer_phys;
        void *reboot_code_buffer;
 
-       if (num_online_cpus() > 1) {
-               pr_err("kexec: error: multiple CPUs still online\n");
-               return;
-       }
+       /*
+        * This can only happen if machine_shutdown() failed to disable some
+        * CPU, and that can only happen if the checks in
+        * machine_kexec_prepare() were not correct. If this fails, we can't
+        * reliably kexec anyway, so BUG_ON is appropriate.
+        */
+       BUG_ON(num_online_cpus() > 1);
 
        page_list = image->head & PAGE_MASK;