ARM: redo TTBR setup code for LPAE

Re-engineer the LPAE TTBR setup code.  Rather than passing some shifted
address in order to fit in a CPU register, pass either a full physical
address (in the case of r4, r5 for TTBR0) or a PFN (for TTBR1).

This removes the ARCH_PGD_SHIFT hack, and the last dangerous user of
cpu_set_ttbr() in the secondary CPU startup code path (which was there
to re-set TTBR1 to the appropriate high physical address space on
Keystone2.)

Tested-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/memory.h

@@ -18,8 +18,6 @@
 #include <linux/types.h>
 #include <linux/sizes.h>
 
-#include <asm/cache.h>
-
 #ifdef CONFIG_NEED_MACH_MEMORY_H
 #include <mach/memory.h>
 #endif
@@ -132,20 +130,6 @@
 #define page_to_phys(page)	(__pfn_to_phys(page_to_pfn(page)))
 #define phys_to_page(phys)	(pfn_to_page(__phys_to_pfn(phys)))
 
-/*
- * Minimum guaranted alignment in pgd_alloc().  The page table pointers passed
- * around in head.S and proc-*.S are shifted by this amount, in order to
- * leave spare high bits for systems with physical address extension.  This
- * does not fully accomodate the 40-bit addressing capability of ARM LPAE, but
- * gives us about 38-bits or so.
- */
-#ifdef CONFIG_ARM_LPAE
-#define ARCH_PGD_SHIFT		L1_CACHE_SHIFT
-#else
-#define ARCH_PGD_SHIFT		0
-#endif
-#define ARCH_PGD_MASK		((1 << ARCH_PGD_SHIFT) - 1)
-
 /*
  * PLAT_PHYS_OFFSET is the offset (from zero) of the start of physical
  * memory.  This is used for XIP and NoMMU kernels, and on platforms that don't

arch/arm/include/asm/proc-fns.h

@@ -125,13 +125,6 @@ extern void cpu_resume(void);
 		ttbr;						\
 	})
 
-#define cpu_set_ttbr(nr, val)					\
-	do {							\
-		u64 ttbr = val;					\
-		__asm__("mcrr	p15, " #nr ", %Q0, %R0, c2"	\
-			: : "r" (ttbr));			\
-	} while (0)
-
 #define cpu_get_pgd()	\
 	({						\
 		u64 pg = cpu_get_ttbr(0);		\

arch/arm/include/asm/smp.h

@@ -61,7 +61,7 @@ asmlinkage void secondary_start_kernel(void);
 struct secondary_data {
 	union {
 		unsigned long mpu_rgn_szr;
-		unsigned long pgdir;
+		u64 pgdir;
 	};
 	unsigned long swapper_pg_dir;
 	void *stack;

arch/arm/kernel/head-nommu.S

@@ -123,7 +123,7 @@ ENTRY(secondary_startup)
 ENDPROC(secondary_startup)
 
 ENTRY(__secondary_switched)
-	ldr	sp, [r7, #8]			@ set up the stack pointer
+	ldr	sp, [r7, #12]			@ set up the stack pointer
 	mov	fp, #0
 	b	secondary_start_kernel
 ENDPROC(__secondary_switched)

arch/arm/kernel/head.S

@@ -131,13 +131,30 @@ ENTRY(stext)
 	 * The following calls CPU specific code in a position independent
 	 * manner.  See arch/arm/mm/proc-*.S for details.  r10 = base of
 	 * xxx_proc_info structure selected by __lookup_processor_type
-	 * above.  On return, the CPU will be ready for the MMU to be
-	 * turned on, and r0 will hold the CPU control register value.
+	 * above.
+	 *
+	 * The processor init function will be called with:
+	 *  r1 - machine type
+	 *  r2 - boot data (atags/dt) pointer
+	 *  r4 - translation table base (low word)
+	 *  r5 - translation table base (high word, if LPAE)
+	 *  r8 - translation table base 1 (pfn if LPAE)
+	 *  r9 - cpuid
+	 *  r13 - virtual address for __enable_mmu -> __turn_mmu_on
+	 *
+	 * On return, the CPU will be ready for the MMU to be turned on,
+	 * r0 will hold the CPU control register value, r1, r2, r4, and
+	 * r9 will be preserved.  r5 will also be preserved if LPAE.
 	 */
 	ldr	r13, =__mmap_switched		@ address to jump to after
 						@ mmu has been enabled
 	adr	lr, BSYM(1f)			@ return (PIC) address
+#ifdef CONFIG_ARM_LPAE
+	mov	r5, #0				@ high TTBR0
+	mov	r8, r4, lsr #12			@ TTBR1 is swapper_pg_dir pfn
+#else
 	mov	r8, r4				@ set TTBR1 to swapper_pg_dir
+#endif
 	ldr	r12, [r10, #PROCINFO_INITFUNC]
 	add	r12, r12, r10
 	ret	r12
@@ -158,7 +175,7 @@ ENDPROC(stext)
  *
  * Returns:
  *  r0, r3, r5-r7 corrupted
- *  r4 = page table (see ARCH_PGD_SHIFT in asm/memory.h)
+ *  r4 = physical page table address
  */
 __create_page_tables:
 	pgtbl	r4, r8				@ page table address
@@ -333,7 +350,6 @@ __create_page_tables:
 #endif
 #ifdef CONFIG_ARM_LPAE
 	sub	r4, r4, #0x1000		@ point to the PGD table
-	mov	r4, r4, lsr #ARCH_PGD_SHIFT
 #endif
 	ret	lr
 ENDPROC(__create_page_tables)
@@ -381,9 +397,9 @@ ENTRY(secondary_startup)
 	adr	r4, __secondary_data
 	ldmia	r4, {r5, r7, r12}		@ address to jump to after
 	sub	lr, r4, r5			@ mmu has been enabled
-	ldr	r4, [r7, lr]			@ get secondary_data.pgdir
-	add	r7, r7, #4
-	ldr	r8, [r7, lr]			@ get secondary_data.swapper_pg_dir
+	add	r3, r7, lr
+	ldrd	r4, [r3, #0]			@ get secondary_data.pgdir
+	ldr	r8, [r3, #8]			@ get secondary_data.swapper_pg_dir
 	adr	lr, BSYM(__enable_mmu)		@ return address
 	mov	r13, r12			@ __secondary_switched address
 	ldr	r12, [r10, #PROCINFO_INITFUNC]
@@ -397,7 +413,7 @@ ENDPROC(secondary_startup_arm)
 	 * r6  = &secondary_data
 	 */
 ENTRY(__secondary_switched)
-	ldr	sp, [r7, #4]			@ get secondary_data.stack
+	ldr	sp, [r7, #12]			@ get secondary_data.stack
 	mov	fp, #0
 	b	secondary_start_kernel
 ENDPROC(__secondary_switched)
@@ -416,12 +432,14 @@ __secondary_data:
 /*
  * Setup common bits before finally enabling the MMU.  Essentially
  * this is just loading the page table pointer and domain access
- * registers.
+ * registers.  All these registers need to be preserved by the
+ * processor setup function (or set in the case of r0)
  *
  *  r0  = cp#15 control register
  *  r1  = machine ID
  *  r2  = atags or dtb pointer
- *  r4  = page table (see ARCH_PGD_SHIFT in asm/memory.h)
+ *  r4  = TTBR pointer (low word)
+ *  r5  = TTBR pointer (high word if LPAE)
  *  r9  = processor ID
  *  r13 = *virtual* address to jump to upon completion
  */
@@ -440,7 +458,9 @@ __enable_mmu:
 #ifdef CONFIG_CPU_ICACHE_DISABLE
 	bic	r0, r0, #CR_I
 #endif
-#ifndef CONFIG_ARM_LPAE
+#ifdef CONFIG_ARM_LPAE
+	mcrr	p15, 0, r4, r5, c2		@ load TTBR0
+#else
 	mov	r5, #(domain_val(DOMAIN_USER, DOMAIN_MANAGER) | \
 		      domain_val(DOMAIN_KERNEL, DOMAIN_MANAGER) | \
 		      domain_val(DOMAIN_TABLE, DOMAIN_MANAGER) | \

arch/arm/kernel/smp.c

@@ -86,9 +86,11 @@ void __init smp_set_ops(struct smp_operations *ops)
 
 static unsigned long get_arch_pgd(pgd_t *pgd)
 {
-	phys_addr_t pgdir = virt_to_idmap(pgd);
-	BUG_ON(pgdir & ARCH_PGD_MASK);
-	return pgdir >> ARCH_PGD_SHIFT;
+#ifdef CONFIG_ARM_LPAE
+	return __phys_to_pfn(virt_to_phys(pgd));
+#else
+	return virt_to_phys(pgd);
+#endif
 }
 
 int __cpu_up(unsigned int cpu, struct task_struct *idle)
@@ -108,7 +110,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
 #endif
 
 #ifdef CONFIG_MMU
-	secondary_data.pgdir = get_arch_pgd(idmap_pgd);
+	secondary_data.pgdir = virt_to_phys(idmap_pgd);
 	secondary_data.swapper_pg_dir = get_arch_pgd(swapper_pg_dir);
 #endif
 	sync_cache_w(&secondary_data);

arch/arm/mach-keystone/platsmp.c

@@ -39,19 +39,6 @@ static int keystone_smp_boot_secondary(unsigned int cpu,
 	return error;
 }
 
-#ifdef CONFIG_ARM_LPAE
-static void __cpuinit keystone_smp_secondary_initmem(unsigned int cpu)
-{
-	pgd_t *pgd0 = pgd_offset_k(0);
-	cpu_set_ttbr(1, __pa(pgd0) + TTBR1_OFFSET);
-	local_flush_tlb_all();
-}
-#else
-static inline void __cpuinit keystone_smp_secondary_initmem(unsigned int cpu)
-{}
-#endif
-
 struct smp_operations keystone_smp_ops __initdata = {
 	.smp_boot_secondary	= keystone_smp_boot_secondary,
-	.smp_secondary_init     = keystone_smp_secondary_initmem,
 };

arch/arm/mm/proc-v7-2level.S

@@ -148,10 +148,10 @@ ENDPROC(cpu_v7_set_pte_ext)
 	 * Macro for setting up the TTBRx and TTBCR registers.
 	 * - \ttb0 and \ttb1 updated with the corresponding flags.
 	 */
-	.macro	v7_ttb_setup, zero, ttbr0, ttbr1, tmp
+	.macro	v7_ttb_setup, zero, ttbr0l, ttbr0h, ttbr1, tmp
 	mcr	p15, 0, \zero, c2, c0, 2	@ TTB control register
-	ALT_SMP(orr	\ttbr0, \ttbr0, #TTB_FLAGS_SMP)
-	ALT_UP(orr	\ttbr0, \ttbr0, #TTB_FLAGS_UP)
+	ALT_SMP(orr	\ttbr0l, \ttbr0l, #TTB_FLAGS_SMP)
+	ALT_UP(orr	\ttbr0l, \ttbr0l, #TTB_FLAGS_UP)
 	ALT_SMP(orr	\ttbr1, \ttbr1, #TTB_FLAGS_SMP)
 	ALT_UP(orr	\ttbr1, \ttbr1, #TTB_FLAGS_UP)
 	mcr	p15, 0, \ttbr1, c2, c0, 1	@ load TTB1

arch/arm/mm/proc-v7-3level.S

@@ -126,11 +126,10 @@ ENDPROC(cpu_v7_set_pte_ext)
 	 * Macro for setting up the TTBRx and TTBCR registers.
 	 * - \ttbr1 updated.
 	 */
-	.macro	v7_ttb_setup, zero, ttbr0, ttbr1, tmp
+	.macro	v7_ttb_setup, zero, ttbr0l, ttbr0h, ttbr1, tmp
 	ldr	\tmp, =swapper_pg_dir		@ swapper_pg_dir virtual address
-	mov	\tmp, \tmp, lsr #ARCH_PGD_SHIFT
-	cmp	\ttbr1, \tmp			@ PHYS_OFFSET > PAGE_OFFSET?
-	mrc	p15, 0, \tmp, c2, c0, 2		@ TTB control register
+	cmp	\ttbr1, \tmp, lsr #12		@ PHYS_OFFSET > PAGE_OFFSET?
+	mrc	p15, 0, \tmp, c2, c0, 2		@ TTB control egister
 	orr	\tmp, \tmp, #TTB_EAE
 	ALT_SMP(orr	\tmp, \tmp, #TTB_FLAGS_SMP)
 	ALT_UP(orr	\tmp, \tmp, #TTB_FLAGS_UP)
@@ -143,13 +142,10 @@ ENDPROC(cpu_v7_set_pte_ext)
 	 */
 	orrls	\tmp, \tmp, #TTBR1_SIZE				@ TTBCR.T1SZ
 	mcr	p15, 0, \tmp, c2, c0, 2				@ TTBCR
-	mov	\tmp, \ttbr1, lsr #(32 - ARCH_PGD_SHIFT)	@ upper bits
-	mov	\ttbr1, \ttbr1, lsl #ARCH_PGD_SHIFT		@ lower bits
+	mov	\tmp, \ttbr1, lsr #20
+	mov	\ttbr1, \ttbr1, lsl #12
 	addls	\ttbr1, \ttbr1, #TTBR1_OFFSET
 	mcrr	p15, 1, \ttbr1, \tmp, c2			@ load TTBR1
-	mov	\tmp, \ttbr0, lsr #(32 - ARCH_PGD_SHIFT)	@ upper bits
-	mov	\ttbr0, \ttbr0, lsl #ARCH_PGD_SHIFT		@ lower bits
-	mcrr	p15, 0, \ttbr0, \tmp, c2			@ load TTBR0
 	.endm
 
 	/*

arch/arm/mm/proc-v7.S

@@ -343,9 +343,9 @@ __v7_setup:
 	and	r10, r0, #0xff000000		@ ARM?
 	teq	r10, #0x41000000
 	bne	3f
-	and	r5, r0, #0x00f00000		@ variant
+	and	r3, r0, #0x00f00000		@ variant
 	and	r6, r0, #0x0000000f		@ revision
-	orr	r6, r6, r5, lsr #20-4		@ combine variant and revision
+	orr	r6, r6, r3, lsr #20-4		@ combine variant and revision
 	ubfx	r0, r0, #4, #12			@ primary part number
 
 	/* Cortex-A8 Errata */
@@ -354,7 +354,7 @@ __v7_setup:
 	bne	2f
 #if defined(CONFIG_ARM_ERRATA_430973) && !defined(CONFIG_ARCH_MULTIPLATFORM)
 
-	teq	r5, #0x00100000			@ only present in r1p*
+	teq	r3, #0x00100000			@ only present in r1p*
 	mrceq	p15, 0, r10, c1, c0, 1		@ read aux control register
 	orreq	r10, r10, #(1 << 6)		@ set IBE to 1
 	mcreq	p15, 0, r10, c1, c0, 1		@ write aux control register
@@ -395,7 +395,7 @@ __v7_setup:
 	mcreq	p15, 0, r10, c15, c0, 1		@ write diagnostic register
 #endif
 #ifdef CONFIG_ARM_ERRATA_743622
-	teq	r5, #0x00200000			@ only present in r2p*
+	teq	r3, #0x00200000			@ only present in r2p*
 	mrceq	p15, 0, r10, c15, c0, 1		@ read diagnostic register
 	orreq	r10, r10, #1 << 6		@ set bit #6
 	mcreq	p15, 0, r10, c15, c0, 1		@ write diagnostic register
@@ -425,10 +425,10 @@ __v7_setup:
 	mcr	p15, 0, r10, c7, c5, 0		@ I+BTB cache invalidate
 #ifdef CONFIG_MMU
 	mcr	p15, 0, r10, c8, c7, 0		@ invalidate I + D TLBs
-	v7_ttb_setup r10, r4, r8, r5		@ TTBCR, TTBRx setup
-	ldr	r5, =PRRR			@ PRRR
+	v7_ttb_setup r10, r4, r5, r8, r3	@ TTBCR, TTBRx setup
+	ldr	r3, =PRRR			@ PRRR
 	ldr	r6, =NMRR			@ NMRR
-	mcr	p15, 0, r5, c10, c2, 0		@ write PRRR
+	mcr	p15, 0, r3, c10, c2, 0		@ write PRRR
 	mcr	p15, 0, r6, c10, c2, 1		@ write NMRR
 #endif
 	dsb					@ Complete invalidations
@@ -437,22 +437,22 @@ __v7_setup:
 	and	r0, r0, #(0xf << 12)		@ ThumbEE enabled field
 	teq	r0, #(1 << 12)			@ check if ThumbEE is present
 	bne	1f
-	mov	r5, #0
-	mcr	p14, 6, r5, c1, c0, 0		@ Initialize TEEHBR to 0
+	mov	r3, #0
+	mcr	p14, 6, r3, c1, c0, 0		@ Initialize TEEHBR to 0
 	mrc	p14, 6, r0, c0, c0, 0		@ load TEECR
 	orr	r0, r0, #1			@ set the 1st bit in order to
 	mcr	p14, 6, r0, c0, c0, 0		@ stop userspace TEEHBR access
 1:
 #endif
-	adr	r5, v7_crval
-	ldmia	r5, {r5, r6}
+	adr	r3, v7_crval
+	ldmia	r3, {r3, r6}
  ARM_BE8(orr	r6, r6, #1 << 25)		@ big-endian page tables
 #ifdef CONFIG_SWP_EMULATE
-	orr     r5, r5, #(1 << 10)              @ set SW bit in "clear"
+	orr     r3, r3, #(1 << 10)              @ set SW bit in "clear"
 	bic     r6, r6, #(1 << 10)              @ clear it in "mmuset"
 #endif
    	mrc	p15, 0, r0, c1, c0, 0		@ read control register
-	bic	r0, r0, r5			@ clear bits them
+	bic	r0, r0, r3			@ clear bits them
 	orr	r0, r0, r6			@ set them
  THUMB(	orr	r0, r0, #1 << 30	)	@ Thumb exceptions
 	ret	lr				@ return to head.S:__ret