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arm64: head.S: get rid of x25 and x26 with 'global' scope

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Currently, x25 and x26 hold the physical addresses of idmap_pg_dir
and swapper_pg_dir, respectively, when running early boot code. But
having registers with 'global' scope in files that contain different
sections with different lifetimes, and that are called by different
CPUs at different times is a bit messy, especially since stashing the
values does not buy us anything in terms of code size or clarity.

So simply replace each reference to x25 or x26 with an adrp instruction
referring to idmap_pg_dir or swapper_pg_dir directly.

Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Ard Biesheuvel 2016-08-16 21:02:32 +02:00 committed by Will Deacon
parent 5a9e3e156e
commit aea73abb90
2 changed files with 13 additions and 17 deletions
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28
arch/arm64/kernel/head.S
View file

@ -214,7 +214,7 @@ ENTRY(stext)
adrp x24, __PHYS_OFFSET
and x23, x24, MIN_KIMG_ALIGN - 1 // KASLR offset, defaults to 0
bl set_cpu_boot_mode_flag
bl __create_page_tables // x25=TTBR0, x26=TTBR1
bl __create_page_tables
/*
* The following calls CPU setup code, see arch/arm64/mm/proc.S for
* details.
@ -311,23 +311,21 @@ ENDPROC(preserve_boot_args)
* been enabled
*/
__create_page_tables:
adrp x25, idmap_pg_dir
adrp x26, swapper_pg_dir
mov x28, lr
/*
* Invalidate the idmap and swapper page tables to avoid potential
* dirty cache lines being evicted.
*/
mov x0, x25
add x1, x26, #SWAPPER_DIR_SIZE
adrp x0, idmap_pg_dir
adrp x1, swapper_pg_dir + SWAPPER_DIR_SIZE
bl __inval_cache_range
/*
* Clear the idmap and swapper page tables.
*/
mov x0, x25
add x6, x26, #SWAPPER_DIR_SIZE
adrp x0, idmap_pg_dir
adrp x6, swapper_pg_dir + SWAPPER_DIR_SIZE
1: stp xzr, xzr, [x0], #16
stp xzr, xzr, [x0], #16
stp xzr, xzr, [x0], #16
@ -340,7 +338,7 @@ __create_page_tables:
/*
* Create the identity mapping.
*/
mov x0, x25 // idmap_pg_dir
adrp x0, idmap_pg_dir
adrp x3, __idmap_text_start // __pa(__idmap_text_start)
#ifndef CONFIG_ARM64_VA_BITS_48
@ -390,7 +388,7 @@ __create_page_tables:
/*
* Map the kernel image (starting with PHYS_OFFSET).
*/
mov x0, x26 // swapper_pg_dir
adrp x0, swapper_pg_dir
mov_q x5, KIMAGE_VADDR + TEXT_OFFSET // compile time __va(_text)
add x5, x5, x23 // add KASLR displacement
create_pgd_entry x0, x5, x3, x6
@ -405,8 +403,8 @@ __create_page_tables:
* accesses (MMU disabled), invalidate the idmap and swapper page
* tables again to remove any speculatively loaded cache lines.
*/
mov x0, x25
add x1, x26, #SWAPPER_DIR_SIZE
adrp x0, idmap_pg_dir
adrp x1, swapper_pg_dir + SWAPPER_DIR_SIZE
dmb sy
bl __inval_cache_range
@ -666,8 +664,6 @@ secondary_startup:
/*
* Common entry point for secondary CPUs.
*/
adrp x25, idmap_pg_dir
adrp x26, swapper_pg_dir
bl __cpu_setup // initialise processor
adr_l x27, __secondary_switch // address to jump to after enabling the MMU
@ -731,8 +727,10 @@ ENTRY(__enable_mmu)
cmp x2, #ID_AA64MMFR0_TGRAN_SUPPORTED
b.ne __no_granule_support
update_early_cpu_boot_status 0, x1, x2
msr ttbr0_el1, x25 // load TTBR0
msr ttbr1_el1, x26 // load TTBR1
adrp x1, idmap_pg_dir
adrp x2, swapper_pg_dir
msr ttbr0_el1, x1 // load TTBR0
msr ttbr1_el1, x2 // load TTBR1
isb
msr sctlr_el1, x0
isb

2
arch/arm64/kernel/sleep.S
View file

@ -102,8 +102,6 @@ ENTRY(cpu_resume)
/* enable the MMU early - so we can access sleep_save_stash by va */
adr_l lr, __enable_mmu /* __cpu_setup will return here */
adr_l x27, _resume_switched /* __enable_mmu will branch here */
adrp x25, idmap_pg_dir
adrp x26, swapper_pg_dir
b __cpu_setup
ENDPROC(cpu_resume)