[POWERPC] ppc64: support CONFIG_DEBUG_PREEMPT
Add CONFIG_DEBUG_PREEMPT support to ppc64: it was useful for testing
get_paca() preemption. Cheat a little, just use debug_smp_processor_id()
in the debug version of get_paca(): it contains all the right checks and
reporting, though get_paca() doesn't really use smp_processor_id().
Use local_paca for what might have been called __raw_get_paca().
Silence harmless warnings from io.h and lparcfg.c with local_paca -
it is okay for iseries_lparcfg_data to be referencing shared_proc
with preemption enabled: all cpus should show the same value for
shared_proc.
Why do other architectures need TRACE_IRQFLAGS_SUPPORT for DEBUG_PREEMPT?
I don't know, ppc64 appears to get along fine without it.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/lparcfg.c b/arch/powerpc/kernel/lparcfg.c
index 6444eaa..ff781b2 100644
--- a/arch/powerpc/kernel/lparcfg.c
+++ b/arch/powerpc/kernel/lparcfg.c
@@ -77,7 +77,7 @@
int processors, max_processors;
unsigned long purr = get_purr();
- shared = (int)(get_lppaca()->shared_proc);
+ shared = (int)(local_paca->lppaca_ptr->shared_proc);
seq_printf(m, "system_active_processors=%d\n",
(int)HvLpConfig_getSystemPhysicalProcessors());
diff --git a/include/asm-powerpc/io.h b/include/asm-powerpc/io.h
index 6805efb..affba70 100644
--- a/include/asm-powerpc/io.h
+++ b/include/asm-powerpc/io.h
@@ -86,7 +86,7 @@
*/
#ifdef CONFIG_PPC64
-#define IO_SET_SYNC_FLAG() do { get_paca()->io_sync = 1; } while(0)
+#define IO_SET_SYNC_FLAG() do { local_paca->io_sync = 1; } while(0)
#else
#define IO_SET_SYNC_FLAG()
#endif
diff --git a/include/asm-powerpc/paca.h b/include/asm-powerpc/paca.h
index c6a5b17..fcd7b42 100644
--- a/include/asm-powerpc/paca.h
+++ b/include/asm-powerpc/paca.h
@@ -21,7 +21,18 @@
#include <asm/mmu.h>
register struct paca_struct *local_paca asm("r13");
+
+#if defined(CONFIG_DEBUG_PREEMPT) && defined(CONFIG_SMP)
+extern unsigned int debug_smp_processor_id(void); /* from linux/smp.h */
+/*
+ * Add standard checks that preemption cannot occur when using get_paca():
+ * otherwise the paca_struct it points to may be the wrong one just after.
+ */
+#define get_paca() ((void) debug_smp_processor_id(), local_paca)
+#else
#define get_paca() local_paca
+#endif
+
#define get_lppaca() (get_paca()->lppaca_ptr)
#define get_slb_shadow() (get_paca()->slb_shadow_ptr)
diff --git a/include/asm-powerpc/percpu.h b/include/asm-powerpc/percpu.h
index 73dc8ba..6b22962 100644
--- a/include/asm-powerpc/percpu.h
+++ b/include/asm-powerpc/percpu.h
@@ -28,7 +28,7 @@
/* var is in discarded region: offset to particular copy we want */
#define per_cpu(var, cpu) (*RELOC_HIDE(&per_cpu__##var, __per_cpu_offset(cpu)))
#define __get_cpu_var(var) (*RELOC_HIDE(&per_cpu__##var, __my_cpu_offset()))
-#define __raw_get_cpu_var(var) (*RELOC_HIDE(&per_cpu__##var, __my_cpu_offset()))
+#define __raw_get_cpu_var(var) (*RELOC_HIDE(&per_cpu__##var, local_paca->data_offset))
/* A macro to avoid #include hell... */
#define percpu_modcopy(pcpudst, src, size) \
diff --git a/include/asm-powerpc/smp.h b/include/asm-powerpc/smp.h
index d037f50..19102bf 100644
--- a/include/asm-powerpc/smp.h
+++ b/include/asm-powerpc/smp.h
@@ -45,7 +45,7 @@
#endif
#ifdef CONFIG_PPC64
-#define raw_smp_processor_id() (get_paca()->paca_index)
+#define raw_smp_processor_id() (local_paca->paca_index)
#define hard_smp_processor_id() (get_paca()->hw_cpu_id)
#else
/* 32-bit */
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 50a94eee..51e2fd0 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -167,7 +167,7 @@
config DEBUG_PREEMPT
bool "Debug preemptible kernel"
- depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
+ depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64)
default y
help
If you say Y here then the kernel will use a debug variant of the