If the boot CPU tries to access per-cpu data of other CPUs before
per cpu areas are set up, it will unexpectedly use offset 0.
Try to catch such accesses by poisoning the __per_cpu_offset array.
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
arch/powerpc/include/asm/percpu.h | 1 +
arch/powerpc/kernel/paca.c | 2 +-
arch/powerpc/kernel/setup_64.c | 2 +-
3 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/include/asm/percpu.h
b/arch/powerpc/include/asm/percpu.h
index 8e5b7d0b851c..6ca1a9fc5725 100644
--- a/arch/powerpc/include/asm/percpu.h
+++ b/arch/powerpc/include/asm/percpu.h
@@ -7,6 +7,7 @@
* Same as asm-generic/percpu.h, except that we store the per cpu offset
* in the paca. Based on the x86-64 implementation.
*/
+#define PER_CPU_OFFSET_POISON 0xfeeeeeeeeeeeeeeeULL
#ifdef CONFIG_SMP
diff --git a/arch/powerpc/kernel/paca.c b/arch/powerpc/kernel/paca.c
index ba593fd60124..914d27c8b84a 100644
--- a/arch/powerpc/kernel/paca.c
+++ b/arch/powerpc/kernel/paca.c
@@ -223,7 +223,7 @@ void __init initialise_paca(struct paca_struct *new_paca,
int cpu)
new_paca->hw_cpu_id = 0xffff;
new_paca->kexec_state = KEXEC_STATE_NONE;
new_paca->__current = &init_task;
- new_paca->data_offset = 0xfeeeeeeeeeeeeeeeULL;
+ new_paca->data_offset = PER_CPU_OFFSET_POISON;
#ifdef CONFIG_PPC_64S_HASH_MMU
new_paca->slb_shadow_ptr = NULL;
#endif
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 5761f08dae95..60f0d1258526 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -812,7 +812,7 @@ static __init int pcpu_cpu_to_node(int cpu)
return early_cpu_to_node(cpu);
}
-unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
+unsigned long __per_cpu_offset[NR_CPUS] __read_mostly = { [0 ... NR_CPUS-1 ] =
PER_CPU_OFFSET_POISON };
EXPORT_SYMBOL(__per_cpu_offset);
void __init setup_per_cpu_areas(void)
--
2.35.1
