[PATCH v2 03/22] ARM: use late patch framework for phys-virt patching

[cyril@ti.com (Cyril Chemparathy)]

This patch replaces the original physical offset patching implementation
with one that uses the newly added patching framework.  In the process, we now
unconditionally initialize the __pv_phys_offset and __pv_offset globals in the
head.S code.

Signed-off-by: Cyril Chemparathy <cyril@ti.com>
---
 arch/arm/Kconfig              |    1 +
 arch/arm/include/asm/memory.h |   26 +++--------
 arch/arm/kernel/armksyms.c    |    4 --
 arch/arm/kernel/head.S        |   95 +++++++----------------------------------
 arch/arm/kernel/module.c      |    5 ---
 arch/arm/kernel/setup.c       |   12 ++++++
 arch/arm/kernel/vmlinux.lds.S |    5 ---
 7 files changed, 36 insertions(+), 112 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 7e552dc..9ac86ea 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -199,6 +199,7 @@ config ARM_PATCH_PHYS_VIRT
 	default y
 	depends on !XIP_KERNEL && MMU
 	depends on !ARCH_REALVIEW || !SPARSEMEM
+	select ARM_RUNTIME_PATCH
 	help
 	  Patch phys-to-virt and virt-to-phys translation functions at
 	  boot and module load time according to the position of the
diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
index e965f1b..3d93779 100644
--- a/arch/arm/include/asm/memory.h
+++ b/arch/arm/include/asm/memory.h
@@ -18,6 +18,8 @@
 #include <linux/types.h>
 #include <linux/sizes.h>
 
+#include <asm/runtime-patch.h>
+
 #ifdef CONFIG_NEED_MACH_MEMORY_H
 #include <mach/memory.h>
 #endif
@@ -151,35 +153,21 @@
 #ifndef __virt_to_phys
 #ifdef CONFIG_ARM_PATCH_PHYS_VIRT
 
-/*
- * Constants used to force the right instruction encodings and shifts
- * so that all we need to do is modify the 8-bit constant field.
- */
-#define __PV_BITS_31_24	0x81000000
-
-extern unsigned long __pv_phys_offset;
-#define PHYS_OFFSET __pv_phys_offset
-
-#define __pv_stub(from,to,instr,type)			\
-	__asm__("@ __pv_stub\n"				\
-	"1:	" instr "	%0, %1, %2\n"		\
-	"	.pushsection .pv_table,\"a\"\n"		\
-	"	.long	1b\n"				\
-	"	.popsection\n"				\
-	: "=r" (to)					\
-	: "r" (from), "I" (type))
+extern unsigned long	__pv_offset;
+extern unsigned long	__pv_phys_offset;
+#define PHYS_OFFSET	__virt_to_phys(PAGE_OFFSET)
 
 static inline unsigned long __virt_to_phys(unsigned long x)
 {
 	unsigned long t;
-	__pv_stub(x, t, "add", __PV_BITS_31_24);
+	early_patch_imm8("add", t, x, __pv_offset, 0);
 	return t;
 }
 
 static inline unsigned long __phys_to_virt(unsigned long x)
 {
 	unsigned long t;
-	__pv_stub(x, t, "sub", __PV_BITS_31_24);
+	early_patch_imm8("sub", t, x, __pv_offset, 0);
 	return t;
 }
 #else
diff --git a/arch/arm/kernel/armksyms.c b/arch/arm/kernel/armksyms.c
index 60d3b73..6b388f8 100644
--- a/arch/arm/kernel/armksyms.c
+++ b/arch/arm/kernel/armksyms.c
@@ -152,7 +152,3 @@ EXPORT_SYMBOL(mcount);
 #endif
 EXPORT_SYMBOL(__gnu_mcount_nc);
 #endif
-
-#ifdef CONFIG_ARM_PATCH_PHYS_VIRT
-EXPORT_SYMBOL(__pv_phys_offset);
-#endif
diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index 3db960e..69a3c09 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -117,7 +117,7 @@ ENTRY(stext)
 	bl	__fixup_smp
 #endif
 #ifdef CONFIG_ARM_PATCH_PHYS_VIRT
-	bl	__fixup_pv_table
+	bl	__fixup_pv_offsets
 #endif
 	bl	__create_page_tables
 
@@ -511,92 +511,29 @@ ENDPROC(fixup_smp)
 
 #ifdef CONFIG_ARM_PATCH_PHYS_VIRT
 
-/* __fixup_pv_table - patch the stub instructions with the delta between
- * PHYS_OFFSET and PAGE_OFFSET, which is assumed to be 16MiB aligned and
- * can be expressed by an immediate shifter operand. The stub instruction
- * has a form of '(add|sub) rd, rn, #imm'.
+/*
+ * __fixup_pv_offsets - update __pv_offset and __pv_phys_offset based on the
+ * runtime location of the kernel.
  */
 	__HEAD
-__fixup_pv_table:
+__fixup_pv_offsets:
 	adr	r0, 1f
-	ldmia	r0, {r3-r5, r7}
+	ldmia	r0, {r3-r6}
 	sub	r3, r0, r3	@ PHYS_OFFSET - PAGE_OFFSET
-	add	r4, r4, r3	@ adjust table start address
-	add	r5, r5, r3	@ adjust table end address
-	add	r7, r7, r3	@ adjust __pv_phys_offset address
-	str	r8, [r7]	@ save computed PHYS_OFFSET to __pv_phys_offset
-	mov	r6, r3, lsr #24	@ constant for add/sub instructions
-	teq	r3, r6, lsl #24 @ must be 16MiB aligned
-THUMB(	it	ne		@ cross section branch )
-	bne	__error
-	str	r6, [r7, #4]	@ save to __pv_offset
-	b	__fixup_a_pv_table
-ENDPROC(__fixup_pv_table)
+	add	r4, r4, r3	@ virt_to_phys(__pv_phys_offset)
+	add	r5, r5, r3	@ virt_to_phys(__pv_offset)
+	add	r6, r6, r3	@ virt_to_phys(PAGE_OFFSET) = PHYS_OFFSET
+	str	r6, [r4]	@ save __pv_phys_offset
+	str	r3, [r5]	@ save __pv_offset
+	mov	pc, lr
+ENDPROC(__fixup_pv_offsets)
 
 	.align
 1:	.long	.
-	.long	__pv_table_begin
-	.long	__pv_table_end
-2:	.long	__pv_phys_offset
-
-	.text
-__fixup_a_pv_table:
-#ifdef CONFIG_THUMB2_KERNEL
-	lsls	r6, #24
-	beq	2f
-	clz	r7, r6
-	lsr	r6, #24
-	lsl	r6, r7
-	bic	r6, #0x0080
-	lsrs	r7, #1
-	orrcs	r6, #0x0080
-	orr	r6, r6, r7, lsl #12
-	orr	r6, #0x4000
-	b	2f
-1:	add     r7, r3
-	ldrh	ip, [r7, #2]
-	and	ip, 0x8f00
-	orr	ip, r6	@ mask in offset bits 31-24
-	strh	ip, [r7, #2]
-2:	cmp	r4, r5
-	ldrcc	r7, [r4], #4	@ use branch for delay slot
-	bcc	1b
-	bx	lr
-#else
-	b	2f
-1:	ldr	ip, [r7, r3]
-	bic	ip, ip, #0x000000ff
-	orr	ip, ip, r6	@ mask in offset bits 31-24
-	str	ip, [r7, r3]
-2:	cmp	r4, r5
-	ldrcc	r7, [r4], #4	@ use branch for delay slot
-	bcc	1b
-	mov	pc, lr
+	.long	__pv_phys_offset
+	.long	__pv_offset
+	.long	PAGE_OFFSET
 #endif
-ENDPROC(__fixup_a_pv_table)
-
-ENTRY(fixup_pv_table)
-	stmfd	sp!, {r4 - r7, lr}
-	ldr	r2, 2f			@ get address of __pv_phys_offset
-	mov	r3, #0			@ no offset
-	mov	r4, r0			@ r0 = table start
-	add	r5, r0, r1		@ r1 = table size
-	ldr	r6, [r2, #4]		@ get __pv_offset
-	bl	__fixup_a_pv_table
-	ldmfd	sp!, {r4 - r7, pc}
-ENDPROC(fixup_pv_table)
 
-	.align
-2:	.long	__pv_phys_offset
-
-	.data
-	.globl	__pv_phys_offset
-	.type	__pv_phys_offset, %object
-__pv_phys_offset:
-	.long	0
-	.size	__pv_phys_offset, . - __pv_phys_offset
-__pv_offset:
-	.long	0
-#endif
 
 #include "head-common.S"
diff --git a/arch/arm/kernel/module.c b/arch/arm/kernel/module.c
index dcebf80..ac13dd5 100644
--- a/arch/arm/kernel/module.c
+++ b/arch/arm/kernel/module.c
@@ -317,11 +317,6 @@ int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
 					         maps[i].txt_sec->sh_addr,
 					         maps[i].txt_sec->sh_size);
 #endif
-#ifdef CONFIG_ARM_PATCH_PHYS_VIRT
-	s = find_mod_section(hdr, sechdrs, ".pv_table");
-	if (s)
-		fixup_pv_table((void *)s->sh_addr, s->sh_size);
-#endif
 	s = find_mod_section(hdr, sechdrs, ".runtime.patch.table");
 	if (s)
 		runtime_patch((void *)s->sh_addr, s->sh_size);
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 669bbf0..59e0f57 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -152,6 +152,18 @@ static union { char c[4]; unsigned long l; } endian_test __initdata = { { 'l', '
 
 DEFINE_PER_CPU(struct cpuinfo_arm, cpu_data);
 
+#ifdef CONFIG_ARM_PATCH_PHYS_VIRT
+
+/*
+ * These are initialized in head.S code prior to BSS getting cleared out.
+ * The initializers here prevent these from landing in the BSS section.
+ */
+unsigned long __pv_offset = 0xdeadbeef;
+unsigned long __pv_phys_offset = 0xdeadbeef;
+EXPORT_SYMBOL(__pv_phys_offset);
+
+#endif
+
 /*
  * Standard memory resources
  */
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index ea35ca0..2080111 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -162,11 +162,6 @@ SECTIONS
 		__smpalt_end = .;
 	}
 #endif
-	.init.pv_table : {
-		__pv_table_begin = .;
-		*(.pv_table)
-		__pv_table_end = .;
-	}
 	.init.runtime_patch_table : {
 		__runtime_patch_table_begin = .;
 		*(.runtime.patch.table)
-- 
1.7.9.5