[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>

4 files changed, 14 insertions, 3 deletions

diff --git a/include/asm-powerpc/io.h b/include/asm-powerpc/io.h
index 6805efb2cb6d..affba7052fb6 100644
--- a/include/asm-powerpc/io.h
+++ b/include/asm-powerpc/io.h
@@ -86,7 +86,7 @@ extern unsigned long pci_dram_offset;
  */
 
 #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 c6a5b1735666..fcd7b428ed0b 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 73dc8ba4010d..6b229626d3ff 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 d037f50580e2..19102bfc14ca 100644
--- a/include/asm-powerpc/smp.h
+++ b/include/asm-powerpc/smp.h
@@ -45,7 +45,7 @@ void generic_mach_cpu_die(void);
 #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 */