powerpc/85xx: Load all early TLB entries at once

Use an AS=1 trampoline TLB entry to allow all normal TLB1 entries to
be loaded at once.  This avoids the need to keep the translation that
code is executing from in the same TLB entry in the final TLB
configuration as during early boot, which in turn is helpful for
relocatable kernels (e.g. kdump) where the kernel is not running from
what would be the first TLB entry.

On e6500, we limit map_mem_in_cams() to the primary hwthread of a
core (the boot cpu is always considered primary, as a kdump kernel
can be entered on any cpu).  Each TLB only needs to be set up once,
and when we do, we don't want another thread to be running when we
create a temporary trampoline TLB1 entry.

Signed-off-by: Scott Wood <scottwood@freescale.com>

4 files changed, 84 insertions, 3 deletions

diff --git a/arch/powerpc/mm/fsl_booke_mmu.c b/arch/powerpc/mm/fsl_booke_mmu.c
index 354ba3c09ef3..bb1f88c10377 100644
--- a/arch/powerpc/mm/fsl_booke_mmu.c
+++ b/arch/powerpc/mm/fsl_booke_mmu.c
@@ -141,8 +141,6 @@ static void settlbcam(int index, unsigned long virt, phys_addr_t phys,
 	tlbcam_addrs[index].start = virt;
 	tlbcam_addrs[index].limit = virt + size - 1;
 	tlbcam_addrs[index].phys = phys;
-
-	loadcam_entry(index);
 }
 
 unsigned long calc_cam_sz(unsigned long ram, unsigned long virt,
@@ -188,6 +186,8 @@ static unsigned long map_mem_in_cams_addr(phys_addr_t phys, unsigned long virt,
 		virt += cam_sz;
 		phys += cam_sz;
 	}
+
+	loadcam_multi(0, i, max_cam_idx);
 	tlbcam_index = i;
 
 #ifdef CONFIG_PPC64
diff --git a/arch/powerpc/mm/mmu_decl.h b/arch/powerpc/mm/mmu_decl.h
index 085b66b10891..27c3a2d3a4f1 100644
--- a/arch/powerpc/mm/mmu_decl.h
+++ b/arch/powerpc/mm/mmu_decl.h
@@ -152,6 +152,7 @@ extern int switch_to_as1(void);
 extern void restore_to_as0(int esel, int offset, void *dt_ptr, int bootcpu);
 #endif
 extern void loadcam_entry(unsigned int index);
+extern void loadcam_multi(int first_idx, int num, int tmp_idx);
 
 struct tlbcam {
 	u32	MAS0;
diff --git a/arch/powerpc/mm/tlb_nohash.c b/arch/powerpc/mm/tlb_nohash.c
index 723a099f6be3..a7381fbdd6ab 100644
--- a/arch/powerpc/mm/tlb_nohash.c
+++ b/arch/powerpc/mm/tlb_nohash.c
@@ -42,6 +42,7 @@
 #include <asm/tlbflush.h>
 #include <asm/tlb.h>
 #include <asm/code-patching.h>
+#include <asm/cputhreads.h>
 #include <asm/hugetlb.h>
 #include <asm/paca.h>
 
@@ -628,10 +629,26 @@ static void early_init_this_mmu(void)
 #ifdef CONFIG_PPC_FSL_BOOK3E
 	if (mmu_has_feature(MMU_FTR_TYPE_FSL_E)) {
 		unsigned int num_cams;
+		int __maybe_unused cpu = smp_processor_id();
+		bool map = true;
 
 		/* use a quarter of the TLBCAM for bolted linear map */
 		num_cams = (mfspr(SPRN_TLB1CFG) & TLBnCFG_N_ENTRY) / 4;
-		linear_map_top = map_mem_in_cams(linear_map_top, num_cams);
+
+		/*
+		 * Only do the mapping once per core, or else the
+		 * transient mapping would cause problems.
+		 */
+#ifdef CONFIG_SMP
+		if (cpu != boot_cpuid &&
+		    (cpu != cpu_first_thread_sibling(cpu) ||
+		     cpu == cpu_first_thread_sibling(boot_cpuid)))
+			map = false;
+#endif
+
+		if (map)
+			linear_map_top = map_mem_in_cams(linear_map_top,
+							 num_cams);
 	}
 #endif
 
diff --git a/arch/powerpc/mm/tlb_nohash_low.S b/arch/powerpc/mm/tlb_nohash_low.S
index 43ff3c797fbf..68c477592e43 100644
--- a/arch/powerpc/mm/tlb_nohash_low.S
+++ b/arch/powerpc/mm/tlb_nohash_low.S
@@ -400,6 +400,7 @@ _GLOBAL(set_context)
  * extern void loadcam_entry(unsigned int index)
  *
  * Load TLBCAM[index] entry in to the L2 CAM MMU
+ * Must preserve r7, r8, r9, and r10
  */
 _GLOBAL(loadcam_entry)
 	mflr	r5
@@ -423,4 +424,66 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_BIG_PHYS)
 	tlbwe
 	isync
 	blr
+
+/*
+ * Load multiple TLB entries at once, using an alternate-space
+ * trampoline so that we don't have to care about whether the same
+ * TLB entry maps us before and after.
+ *
+ * r3 = first entry to write
+ * r4 = number of entries to write
+ * r5 = temporary tlb entry
+ */
+_GLOBAL(loadcam_multi)
+	mflr	r8
+
+	/*
+	 * Set up temporary TLB entry that is the same as what we're
+	 * running from, but in AS=1.
+	 */
+	bl	1f
+1:	mflr	r6
+	tlbsx	0,r8
+	mfspr	r6,SPRN_MAS1
+	ori	r6,r6,MAS1_TS
+	mtspr	SPRN_MAS1,r6
+	mfspr	r6,SPRN_MAS0
+	rlwimi	r6,r5,MAS0_ESEL_SHIFT,MAS0_ESEL_MASK
+	mr	r7,r5
+	mtspr	SPRN_MAS0,r6
+	isync
+	tlbwe
+	isync
+
+	/* Switch to AS=1 */
+	mfmsr	r6
+	ori	r6,r6,MSR_IS|MSR_DS
+	mtmsr	r6
+	isync
+
+	mr	r9,r3
+	add	r10,r3,r4
+2:	bl	loadcam_entry
+	addi	r9,r9,1
+	cmpw	r9,r10
+	mr	r3,r9
+	blt	2b
+
+	/* Return to AS=0 and clear the temporary entry */
+	mfmsr	r6
+	rlwinm.	r6,r6,0,~(MSR_IS|MSR_DS)
+	mtmsr	r6
+	isync
+
+	li	r6,0
+	mtspr	SPRN_MAS1,r6
+	rlwinm	r6,r7,MAS0_ESEL_SHIFT,MAS0_ESEL_MASK
+	oris	r6,r6,MAS0_TLBSEL(1)@h
+	mtspr	SPRN_MAS0,r6
+	isync
+	tlbwe
+	isync
+
+	mtlr	r8
+	blr
 #endif