With dynamic PACAs, the kexecing CPU's PACA won't lie within the kernel
static data and there is a chance that something may stomp it when preparing
to kexec. This patch switches this final CPU to a static PACA just before
we pull the switch.
Signed-off-by: Matt Evans <m...@ozlabs.org>
---
v2: Changes from Milton's review:
- Use setup_paca() and move from setup_64.c,
- SLB cache inval. not required,
- Adjust 'paca' (oops..), and
- Poison data_offset/per_cpu_offset
arch/powerpc/include/asm/paca.h | 2 +-
arch/powerpc/kernel/machine_kexec_64.c | 20 ++++++++++++++++++++
arch/powerpc/kernel/paca.c | 10 ++++++++++
arch/powerpc/kernel/setup_64.c | 10 ----------
4 files changed, 31 insertions(+), 11 deletions(-)
diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index 8ce7963..1ff6662 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h
@@ -146,7 +146,7 @@ struct paca_struct {
extern struct paca_struct *paca;
extern __initdata struct paca_struct boot_paca;
extern void initialise_paca(struct paca_struct *new_paca, int cpu);
-
+extern void setup_paca(struct paca_struct *new_paca);
extern void allocate_pacas(void);
extern void free_unused_pacas(void);
diff --git a/arch/powerpc/kernel/machine_kexec_64.c
b/arch/powerpc/kernel/machine_kexec_64.c
index 26f9900..c4d0123 100644
--- a/arch/powerpc/kernel/machine_kexec_64.c
+++ b/arch/powerpc/kernel/machine_kexec_64.c
@@ -273,6 +273,12 @@ static void kexec_prepare_cpus(void)
static union thread_union kexec_stack __init_task_data =
{ };
+/*
+ * For similar reasons to the stack above, the kexecing CPU needs to be on a
+ * static PACA; we switch to kexec_paca.
+ */
+struct paca_struct kexec_paca;
+
/* Our assembly helper, in kexec_stub.S */
extern NORET_TYPE void kexec_sequence(void *newstack, unsigned long start,
void *image, void *control,
@@ -300,6 +306,20 @@ void default_machine_kexec(struct kimage *image)
kexec_stack.thread_info.task = current_thread_info()->task;
kexec_stack.thread_info.flags = 0;
+ /* We need a static PACA, too; copy this CPU's PACA over and switch to
+ * it. Also poison per_cpu_offset to catch anyone using non-static
+ * data.
+ */
+ memcpy(&kexec_paca, get_paca(), sizeof(struct paca_struct));
+ kexec_paca.data_offset = 0xedeaddeadeeeeeeeUL;
+ paca = (struct paca_struct *)RELOC_HIDE(&kexec_paca, 0) -
+ kexec_paca.paca_index;
+ setup_paca(&kexec_paca);
+
+ /* XXX: If anyone does 'dynamic lppacas' this will also need to be
+ * switched to a static version!
+ */
+
/* Some things are best done in assembly. Finding globals with
* a toc is easier in C, so pass in what we can.
*/
diff --git a/arch/powerpc/kernel/paca.c b/arch/powerpc/kernel/paca.c
index f88acf0..3db8d64 100644
--- a/arch/powerpc/kernel/paca.c
+++ b/arch/powerpc/kernel/paca.c
@@ -105,6 +105,16 @@ void __init initialise_paca(struct paca_struct *new_paca,
int cpu)
#endif /* CONFIG_PPC_STD_MMU_64 */
}
+/* Put the paca pointer into r13 and SPRG_PACA */
+void setup_paca(struct paca_struct *new_paca)
+{
+ local_paca = new_paca;
+ mtspr(SPRN_SPRG_PACA, local_paca);
+#ifdef CONFIG_PPC_BOOK3E
+ mtspr(SPRN_SPRG_TLB_EXFRAME, local_paca->extlb);
+#endif
+}
+
static int __initdata paca_size;
void __init allocate_pacas(void)
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index f3fb5a7..6efbed4 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -142,16 +142,6 @@ early_param("smt-enabled", early_smt_enabled);
#define check_smt_enabled()
#endif /* CONFIG_SMP */
-/* Put the paca pointer into r13 and SPRG_PACA */
-static void __init setup_paca(struct paca_struct *new_paca)
-{
- local_paca = new_paca;
- mtspr(SPRN_SPRG_PACA, local_paca);
-#ifdef CONFIG_PPC_BOOK3E
- mtspr(SPRN_SPRG_TLB_EXFRAME, local_paca->extlb);
-#endif
-}
-
/*
* Early initialization entry point. This is called by head.S
* with MMU translation disabled. We rely on the "feature" of
--
1.6.3.3
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