powerpc: purge all the prefetched instructions for the coherent icache flush

As Benjamin Herrenschmidt has indicated, we still need a dummy icbi to
purge all the prefetched instructions from the ifetch buffers for the
snooping icache. We also need a sync before the icbi to order the
actual stores to memory that might have modified instructions with
the icbi.
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/include/asm/cache.h

@@ -41,8 +41,20 @@ struct ppc64_caches {
 extern struct ppc64_caches ppc64_caches;
 #endif /* __powerpc64__ && ! __ASSEMBLY__ */
 
-#if !defined(__ASSEMBLY__)
+#if defined(__ASSEMBLY__)
+/*
+ * For a snooping icache, we still need a dummy icbi to purge all the
+ * prefetched instructions from the ifetch buffers. We also need a sync
+ * before the icbi to order the the actual stores to memory that might
+ * have modified instructions with the icbi.
+ */
+#define PURGE_PREFETCHED_INS	\
+	sync;			\
+	icbi	0,r3;		\
+	sync;			\
+	isync
 
+#else
 #define __read_mostly __attribute__((__section__(".data..read_mostly")))
 
 #ifdef CONFIG_6xx

arch/powerpc/kernel/misc_32.S

@@ -344,7 +344,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_UNIFIED_ID_CACHE)
  */
 _KPROBE(flush_icache_range)
 BEGIN_FTR_SECTION
-	isync
+	PURGE_PREFETCHED_INS
 	blr				/* for 601, do nothing */
 END_FTR_SECTION_IFSET(CPU_FTR_COHERENT_ICACHE)
 	li	r5,L1_CACHE_BYTES-1
@@ -448,6 +448,7 @@ _GLOBAL(invalidate_dcache_range)
  */
 _GLOBAL(__flush_dcache_icache)
 BEGIN_FTR_SECTION
+	PURGE_PREFETCHED_INS
 	blr
 END_FTR_SECTION_IFSET(CPU_FTR_COHERENT_ICACHE)
 	rlwinm	r3,r3,0,0,31-PAGE_SHIFT		/* Get page base address */
@@ -489,6 +490,7 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_TYPE_44x)
  */
 _GLOBAL(__flush_dcache_icache_phys)
 BEGIN_FTR_SECTION
+	PURGE_PREFETCHED_INS
 	blr					/* for 601, do nothing */
 END_FTR_SECTION_IFSET(CPU_FTR_COHERENT_ICACHE)
 	mfmsr	r10

arch/powerpc/kernel/misc_64.S

@@ -67,6 +67,7 @@ PPC64_CACHES:
 
 _KPROBE(flush_icache_range)
 BEGIN_FTR_SECTION
+	PURGE_PREFETCHED_INS
 	blr
 END_FTR_SECTION_IFSET(CPU_FTR_COHERENT_ICACHE)
 /*
@@ -211,6 +212,11 @@ _GLOBAL(__flush_dcache_icache)
  * Different systems have different cache line sizes
  */
 
+BEGIN_FTR_SECTION
+	PURGE_PREFETCHED_INS
+	blr
+END_FTR_SECTION_IFSET(CPU_FTR_COHERENT_ICACHE)
+
 /* Flush the dcache */
  	ld	r7,PPC64_CACHES@toc(r2)
 	clrrdi	r3,r3,PAGE_SHIFT           	    /* Page align */