[PATCH] powerpc/fsl-booke: Move loadcam_entry back to asm code to fix SMP ftrace

[Kumar Gala]

When we build with ftrace enabled its possible that loadcam_entry would
have used the stack pointer (even though the code doesn't need it).  We
call loadcam_entry in __secondary_start before the stack is setup.  To
ensure that loadcam_entry doesn't use the stack pointer the easiest
solution is to just have it in asm code.

Signed-off-by: Kumar Gala <galak at kernel.crashing.org>
---
For 2.6.34 stable commit 78f622377f7d31d988db350a43c5689dd5f31876

 arch/powerpc/kernel/asm-offsets.c |    8 ++++++++
 arch/powerpc/mm/fsl_booke_mmu.c   |   25 +++----------------------
 arch/powerpc/mm/mmu_decl.h        |   10 +++++++++-
 arch/powerpc/mm/tlb_nohash_low.S  |   28 ++++++++++++++++++++++++++++
 4 files changed, 48 insertions(+), 23 deletions(-)

diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 957ceb7..0271b58 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -448,6 +448,14 @@ int main(void)
 	DEFINE(PGD_T_LOG2, PGD_T_LOG2);
 	DEFINE(PTE_T_LOG2, PTE_T_LOG2);
 #endif
+#ifdef CONFIG_FSL_BOOKE
+	DEFINE(TLBCAM_SIZE, sizeof(struct tlbcam));
+	DEFINE(TLBCAM_MAS0, offsetof(struct tlbcam, MAS0));
+	DEFINE(TLBCAM_MAS1, offsetof(struct tlbcam, MAS1));
+	DEFINE(TLBCAM_MAS2, offsetof(struct tlbcam, MAS2));
+	DEFINE(TLBCAM_MAS3, offsetof(struct tlbcam, MAS3));
+	DEFINE(TLBCAM_MAS7, offsetof(struct tlbcam, MAS7));
+#endif
 
 #ifdef CONFIG_KVM_EXIT_TIMING
 	DEFINE(VCPU_TIMING_EXIT_TBU, offsetof(struct kvm_vcpu,
diff --git a/arch/powerpc/mm/fsl_booke_mmu.c b/arch/powerpc/mm/fsl_booke_mmu.c
index 1ed6b52..cdc7526 100644
--- a/arch/powerpc/mm/fsl_booke_mmu.c
+++ b/arch/powerpc/mm/fsl_booke_mmu.c
@@ -2,7 +2,7 @@
  * Modifications by Kumar Gala (galak at kernel.crashing.org) to support
  * E500 Book E processors.
  *
- * Copyright 2004 Freescale Semiconductor, Inc
+ * Copyright 2004,2010 Freescale Semiconductor, Inc.
  *
  * This file contains the routines for initializing the MMU
  * on the 4xx series of chips.
@@ -56,19 +56,13 @@
 
 unsigned int tlbcam_index;
 
-#define NUM_TLBCAMS	(64)
 
 #if defined(CONFIG_LOWMEM_CAM_NUM_BOOL) && (CONFIG_LOWMEM_CAM_NUM >= NUM_TLBCAMS)
 #error "LOWMEM_CAM_NUM must be less than NUM_TLBCAMS"
 #endif
 
-struct tlbcam {
-	u32	MAS0;
-	u32	MAS1;
-	unsigned long	MAS2;
-	u32	MAS3;
-	u32	MAS7;
-} TLBCAM[NUM_TLBCAMS];
+#define NUM_TLBCAMS	(64)
+struct tlbcam TLBCAM[NUM_TLBCAMS];
 
 struct tlbcamrange {
 	unsigned long start;
@@ -109,19 +103,6 @@ unsigned long p_mapped_by_tlbcam(phys_addr_t pa)
 	return 0;
 }
 
-void loadcam_entry(int idx)
-{
-	mtspr(SPRN_MAS0, TLBCAM[idx].MAS0);
-	mtspr(SPRN_MAS1, TLBCAM[idx].MAS1);
-	mtspr(SPRN_MAS2, TLBCAM[idx].MAS2);
-	mtspr(SPRN_MAS3, TLBCAM[idx].MAS3);
-
-	if (mmu_has_feature(MMU_FTR_BIG_PHYS))
-		mtspr(SPRN_MAS7, TLBCAM[idx].MAS7);
-
-	asm volatile("isync;tlbwe;isync" : : : "memory");
-}
-
 /*
  * Set up one of the I/D BAT (block address translation) register pairs.
  * The parameters are not checked; in particular size must be a power
diff --git a/arch/powerpc/mm/mmu_decl.h b/arch/powerpc/mm/mmu_decl.h
index eb11d5d..63b84a0 100644
--- a/arch/powerpc/mm/mmu_decl.h
+++ b/arch/powerpc/mm/mmu_decl.h
@@ -144,7 +144,15 @@ extern unsigned long mmu_mapin_ram(unsigned long top);
 extern void MMU_init_hw(void);
 extern unsigned long mmu_mapin_ram(unsigned long top);
 extern void adjust_total_lowmem(void);
-
+extern void loadcam_entry(unsigned int index);
+
+struct tlbcam {
+	u32	MAS0;
+	u32	MAS1;
+	unsigned long	MAS2;
+	u32	MAS3;
+	u32	MAS7;
+};
 #elif defined(CONFIG_PPC32)
 /* anything 32-bit except 4xx or 8xx */
 extern void MMU_init_hw(void);
diff --git a/arch/powerpc/mm/tlb_nohash_low.S b/arch/powerpc/mm/tlb_nohash_low.S
index e925cb5..cfa7682 100644
--- a/arch/powerpc/mm/tlb_nohash_low.S
+++ b/arch/powerpc/mm/tlb_nohash_low.S
@@ -365,3 +365,31 @@ _GLOBAL(set_context)
 #else
 #error Unsupported processor type !
 #endif
+
+#if defined(CONFIG_FSL_BOOKE)
+/*
+ * extern void loadcam_entry(unsigned int index)
+ *
+ * Load TLBCAM[index] entry in to the L2 CAM MMU
+ */
+_GLOBAL(loadcam_entry)
+	LOAD_REG_ADDR(r4, TLBCAM)
+	mulli	r5,r3,TLBCAM_SIZE
+	add	r3,r5,r4
+	lwz	r4,TLBCAM_MAS0(r3)
+	mtspr	SPRN_MAS0,r4
+	lwz	r4,TLBCAM_MAS1(r3)
+	mtspr	SPRN_MAS1,r4
+	PPC_LL	r4,TLBCAM_MAS2(r3)
+	mtspr	SPRN_MAS2,r4
+	lwz	r4,TLBCAM_MAS3(r3)
+	mtspr	SPRN_MAS3,r4
+BEGIN_MMU_FTR_SECTION
+	lwz	r4,TLBCAM_MAS7(r3)
+	mtspr	SPRN_MAS7,r4
+END_MMU_FTR_SECTION_IFSET(MMU_FTR_BIG_PHYS)
+	isync
+	tlbwe
+	isync
+	blr
+#endif
-- 
1.6.0.6