Commit 2103f6cb authored by Stephen Warren's avatar Stephen Warren Committed by Russell King

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: default avatarStephen Warren <swarren@nvidia.com>
Acked-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 00efaa02
...@@ -88,4 +88,7 @@ static inline u32 mpidr_hash_size(void) ...@@ -88,4 +88,7 @@ static inline u32 mpidr_hash_size(void)
{ {
return 1 << mpidr_hash.bits; return 1 << mpidr_hash.bits;
} }
extern int platform_can_cpu_hotplug(void);
#endif #endif
...@@ -15,6 +15,7 @@ ...@@ -15,6 +15,7 @@
#include <asm/mmu_context.h> #include <asm/mmu_context.h>
#include <asm/cacheflush.h> #include <asm/cacheflush.h>
#include <asm/mach-types.h> #include <asm/mach-types.h>
#include <asm/smp_plat.h>
#include <asm/system_misc.h> #include <asm/system_misc.h>
extern const unsigned char relocate_new_kernel[]; extern const unsigned char relocate_new_kernel[];
...@@ -38,6 +39,14 @@ int machine_kexec_prepare(struct kimage *image) ...@@ -38,6 +39,14 @@ int machine_kexec_prepare(struct kimage *image)
__be32 header; __be32 header;
int i, err; 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 * No segment at default ATAGs address. try to locate
* a dtb using magic. * a dtb using magic.
...@@ -134,10 +143,13 @@ void machine_kexec(struct kimage *image) ...@@ -134,10 +143,13 @@ void machine_kexec(struct kimage *image)
unsigned long reboot_code_buffer_phys; unsigned long reboot_code_buffer_phys;
void *reboot_code_buffer; void *reboot_code_buffer;
if (num_online_cpus() > 1) { /*
pr_err("kexec: error: multiple CPUs still online\n"); * This can only happen if machine_shutdown() failed to disable some
return; * 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; page_list = image->head & PAGE_MASK;
......
...@@ -145,6 +145,16 @@ int boot_secondary(unsigned int cpu, struct task_struct *idle) ...@@ -145,6 +145,16 @@ int boot_secondary(unsigned int cpu, struct task_struct *idle)
return -ENOSYS; 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 #ifdef CONFIG_HOTPLUG_CPU
static void percpu_timer_stop(void); static void percpu_timer_stop(void);
......
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