Hello,
Le 13/03/2019 à 04:42, Alastair D'Silva a écrit :
From: Alastair D'Silva <alast...@d-silva.org>
When building an LTO kernel, the existing code generates warnings:
./arch/powerpc/include/asm/paca.h:37:30: warning: register of
‘local_paca’ used for multiple global register variables
register struct paca_struct *local_paca asm("r13");
^
./arch/powerpc/include/asm/paca.h:37:30: note: conflicts with
‘local_paca’
How do you build a LTO kernel ?
This patch reworks local_paca into an inline getter & setter function,
which addresses the warning.
This patch adds sparse warnings, see
https://patchwork.ozlabs.org/patch/1055875/
Generated ASM from this patch is broadly similar (addresses have
changed and the compiler uses different GPRs in some places).
Your text might be confusion. When I read it the first time I thought
you were saying that the compiler was now using another GPR than r13.
Signed-off-by: Alastair D'Silva <alast...@d-silva.org>
I guess the same has to be done for current, see
arch/powerpc/include/asm/current.h :
/*
* We keep `current' in r2 for speed.
*/
register struct task_struct *current asm ("r2");
---
arch/powerpc/include/asm/paca.h | 44 +++++++++++++++++++++++----------
arch/powerpc/kernel/paca.c | 2 +-
2 files changed, 32 insertions(+), 14 deletions(-)
diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index e843bc5d1a0f..9c9e2dea0f9b 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h
@@ -34,19 +34,6 @@
#include <asm/cpuidle.h>
#include <asm/atomic.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
-
#ifdef CONFIG_PPC_PSERIES
#define get_lppaca() (get_paca()->lppaca_ptr)
#endif
@@ -266,6 +253,37 @@ struct paca_struct {
#endif
} ____cacheline_aligned;
+#if defined(CONFIG_DEBUG_PREEMPT) && defined(CONFIG_SMP)
+extern unsigned int debug_smp_processor_id(void); /* from linux/smp.h */
+#endif
Why moving this down, why not leaving at the same place as before ?
If you really need to move it, you should remove the 'extern' at the
same time to make checkpatch happy.
+
+static inline struct paca_struct *get_paca_no_preempt_check(void)
+{
+ register struct paca_struct *paca asm("r13");
Should be a blank line there.
+ return paca;
+}
+
+static inline struct paca_struct *get_paca(void)
+{
+#if defined(CONFIG_DEBUG_PREEMPT) && defined(CONFIG_SMP)
+ /*
+ * 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.
+ */
+ debug_smp_processor_id();
+#endif
+ return get_paca_no_preempt_check();
+}
+
+#define local_paca get_paca_no_preempt_check()
+
+static inline void set_paca(struct paca_struct *new)
+{
+ register struct paca_struct *paca asm("r13");
Blank line should be added here.
+ paca = new;
+}
+
+
extern void copy_mm_to_paca(struct mm_struct *mm);
extern struct paca_struct **paca_ptrs;
extern void initialise_paca(struct paca_struct *new_paca, int cpu);
diff --git a/arch/powerpc/kernel/paca.c b/arch/powerpc/kernel/paca.c
index 913bfca09c4f..ae5c243f9d5a 100644
--- a/arch/powerpc/kernel/paca.c
+++ b/arch/powerpc/kernel/paca.c
@@ -172,7 +172,7 @@ void __init initialise_paca(struct paca_struct *new_paca,
int cpu)
void setup_paca(struct paca_struct *new_paca)
{
/* Setup r13 */
- local_paca = new_paca;
+ set_paca(new_paca);
#ifdef CONFIG_PPC_BOOK3E
/* On Book3E, initialize the TLB miss exception frames */
Christophe
