[PATCH 2/3] arm64: remove __calc_phys_offset

Ard Biesheuvel
2015-03-17T10:11:13Z

This removes the function __calc_phys_offset and all open coded
virtual to physical address translations using the offset kept
in x28.

Instead, just use absolute or PC-relative symbol references as
appropriate when referring to virtual or physical addresses,
respectively.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
arch/arm64/kernel/head.S | 49 ++++++++++++------------------------------------
1 file changed, 12 insertions(+), 37 deletions(-)

diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index fb912314d5e1..1651c0fd50e6 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -36,8 +36,6 @@
#include <asm/page.h>
#include <asm/virt.h>

-#define KERNEL_RAM_VADDR (PAGE_OFFSET + TEXT_OFFSET)
-
#if (TEXT_OFFSET & 0xfff) != 0
#error TEXT_OFFSET must be at least 4KB aligned
#elif (PAGE_OFFSET & 0x1fffff) != 0
@@ -46,13 +44,6 @@
#error TEXT_OFFSET must be less than 2MB
#endif

- .macro pgtbl, ttb0, ttb1, virt_to_phys
- ldr \ttb1, =swapper_pg_dir
- ldr \ttb0, =idmap_pg_dir
- add \ttb1, \ttb1, \virt_to_phys
- add \ttb0, \ttb0, \virt_to_phys
- .endm
-
#ifdef CONFIG_ARM64_64K_PAGES
#define BLOCK_SHIFT PAGE_SHIFT
#define BLOCK_SIZE PAGE_SIZE
@@ -63,7 +54,7 @@
#define TABLE_SHIFT PUD_SHIFT
#endif

-#define KERNEL_START KERNEL_RAM_VADDR
+#define KERNEL_START _text
#define KERNEL_END _end

/*
@@ -242,7 +233,7 @@ section_table:
ENTRY(stext)
mov x21, x0 // x21=FDT
bl el2_setup // Drop to EL1, w20=cpu_boot_mode
- bl __calc_phys_offset // x24=PHYS_OFFSET, x28=PHYS_OFFSET-PAGE_OFFSET
+ adrp x24, KERNEL_START - TEXT_OFFSET // x24=PHYS_OFFSET
bl set_cpu_boot_mode_flag

bl __vet_fdt
@@ -343,7 +334,8 @@ ENDPROC(__vet_fdt)
* - pgd entry for fixed mappings (TTBR1)
*/
__create_page_tables:
- pgtbl x25, x26, x28 // idmap_pg_dir and swapper_pg_dir addresses
+ adrp x25, idmap_pg_dir
+ adrp x26, swapper_pg_dir
mov x27, lr

/*
@@ -372,12 +364,10 @@ __create_page_tables:
* Create the identity mapping.
*/
mov x0, x25 // idmap_pg_dir
- ldr x3, =KERNEL_START
- add x3, x3, x28 // __pa(KERNEL_START)
+ adrp x3, KERNEL_START // __pa(KERNEL_START)
create_pgd_entry x0, x3, x5, x6
- ldr x6, =KERNEL_END
mov x5, x3 // __pa(KERNEL_START)
- add x6, x6, x28 // __pa(KERNEL_END)
+ adr_l x6, KERNEL_END // __pa(KERNEL_END)
create_block_map x0, x7, x3, x5, x6

/*
@@ -386,7 +376,7 @@ __create_page_tables:
mov x0, x26 // swapper_pg_dir
mov x5, #PAGE_OFFSET
create_pgd_entry x0, x5, x3, x6
- ldr x6, =KERNEL_END
+ ldr x6, =KERNEL_END // __va(KERNEL_END)
mov x3, x24 // phys offset
create_block_map x0, x7, x3, x5, x6

@@ -538,8 +528,7 @@ ENDPROC(el2_setup)
* in x20. See arch/arm64/include/asm/virt.h for more info.
*/
ENTRY(set_cpu_boot_mode_flag)
- ldr x1, =__boot_cpu_mode // Compute __boot_cpu_mode
- add x1, x1, x28
+ adr_l x1, __boot_cpu_mode
cmp w20, #BOOT_CPU_MODE_EL2
b.ne 1f
add x1, x1, #4
@@ -570,7 +559,7 @@ ENTRY(__boot_cpu_mode)
*/
ENTRY(secondary_holding_pen)
bl el2_setup // Drop to EL1, w20=cpu_boot_mode
- bl __calc_phys_offset // x24=PHYS_OFFSET, x28=PHYS_OFFSET-PAGE_OFFSET
+ adrp x24, KERNEL_START - TEXT_OFFSET // x24=PHYS_OFFSET
bl set_cpu_boot_mode_flag
mrs x0, mpidr_el1
ldr x1, =MPIDR_HWID_BITMASK
@@ -589,7 +578,7 @@ ENDPROC(secondary_holding_pen)
*/
ENTRY(secondary_entry)
bl el2_setup // Drop to EL1
- bl __calc_phys_offset // x24=PHYS_OFFSET, x28=PHYS_OFFSET-PAGE_OFFSET
+ adrp x24, KERNEL_START - TEXT_OFFSET // x24=PHYS_OFFSET
bl set_cpu_boot_mode_flag
b secondary_startup
ENDPROC(secondary_entry)
@@ -598,7 +587,8 @@ ENTRY(secondary_startup)
/*
* Common entry point for secondary CPUs.
*/
- pgtbl x25, x26, x28 // x25=TTBR0, x26=TTBR1
+ adrp x25, idmap_pg_dir
+ adrp x26, swapper_pg_dir
bl __cpu_setup // initialise processor

ldr x21, =secondary_data
@@ -636,18 +626,3 @@ __enable_mmu:
isb
br x27
ENDPROC(__enable_mmu)
-
-/*
- * Calculate the start of physical memory.
- */
-__calc_phys_offset:
- adr x0, 1f
- ldp x1, x2, [x0]
- sub x28, x0, x1 // x28 = PHYS_OFFSET - PAGE_OFFSET
- add x24, x2, x28 // x24 = PHYS_OFFSET
- ret
-ENDPROC(__calc_phys_offset)
-
- .align 3
-1: .quad .
- .quad PAGE_OFFSET
--
1.8.3.2