diff options
| author | Stephen Warren <swarren@nvidia.com> | 2013-08-02 20:52:49 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2013-08-13 20:23:18 +0100 |
| commit | 2103f6cba61a8b8bea3fc1b63661d830a2125e76 (patch) | |
| tree | ecc5f6e4df5631932b38e9eb1d8dd7cd8251ed2b /arch | |
| parent | 00efaa0250939dc148e2d3104fb3c18395d24a2d (diff) | |
ARM: 7807/1: kexec: validate CPU hotplug support
Architectures should fully validate whether kexec is possible as part of
machine_kexec_prepare(), so that user-space's kexec_load() operation can
report any problems. Performing validation in machine_kexec() itself is
too late, since it is not allowed to return.
Prior to this patch, ARM's machine_kexec() was testing after-the-fact
whether machine_kexec_prepare() was able to disable all but one CPU.
Instead, modify machine_kexec_prepare() to validate all conditions
necessary for machine_kexec_prepare()'s to succeed. BUG if the validation
succeeded, yet disabling the CPUs didn't actually work.
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm/include/asm/smp_plat.h | 3 | ||||
| -rw-r--r-- | arch/arm/kernel/machine_kexec.c | 20 | ||||
| -rw-r--r-- | arch/arm/kernel/smp.c | 10 |
3 files changed, 29 insertions, 4 deletions
diff --git a/arch/arm/include/asm/smp_plat.h b/arch/arm/include/asm/smp_plat.h index 6462a721ebd..a252c0bfacf 100644 --- a/arch/arm/include/asm/smp_plat.h +++ b/arch/arm/include/asm/smp_plat.h @@ -88,4 +88,7 @@ static inline u32 mpidr_hash_size(void) { return 1 << mpidr_hash.bits; } + +extern int platform_can_cpu_hotplug(void); + #endif diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c index 4fb074c446b..d7c82df6924 100644 --- 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[]; @@ -39,6 +40,14 @@ int machine_kexec_prepare(struct kimage *image) 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; diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index c2b4f8f0be9..2dc19349eb1 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -145,6 +145,16 @@ int boot_secondary(unsigned int cpu, struct task_struct *idle) return -ENOSYS; } +int platform_can_cpu_hotplug(void) +{ +#ifdef CONFIG_HOTPLUG_CPU + if (smp_ops.cpu_kill) + return 1; +#endif + + return 0; +} + #ifdef CONFIG_HOTPLUG_CPU static void percpu_timer_stop(void); |