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arm64: merge __enable_mmu and __turn_mmu_on 

Enabling of the MMU is split into two functions, with an align and
a branch in the middle. On arm64, the entire kernel Image is ID mapped
so this is really not necessary, and we can just merge it into a
single function.

Also replaces an open coded adrp/add reference to __enable_mmu pair
with adr_l.

Tested-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-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 2015-03-17 08:59:53 +01:00 committed by Will Deacon
parent b1c98297fe
commit 8b0a95753a
1 changed files with 7 additions and 26 deletions
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33
arch/arm64/kernel/head.S
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@ -255,8 +255,7 @@ ENTRY(stext)
*/
ldr x27, =__mmap_switched // address to jump to after
// MMU has been enabled
adrp lr, __enable_mmu // return (PIC) address
add lr, lr, #:lo12:__enable_mmu
adr_l lr, __enable_mmu // return (PIC) address
b __cpu_setup // initialise processor
ENDPROC(stext)
@ -615,11 +614,12 @@ ENDPROC(__secondary_switched)
#endif /* CONFIG_SMP */
/*
* Setup common bits before finally enabling the MMU. Essentially this is just
* loading the page table pointer and vector base registers.
* Enable the MMU.
*
* On entry to this code, x0 must contain the SCTLR_EL1 value for turning on
* the MMU.
* x0 = SCTLR_EL1 value for turning on the MMU.
* x27 = *virtual* address to jump to upon completion
*
* other registers depend on the function called upon completion
*/
__enable_mmu:
ldr x5, =vectors
@ -627,29 +627,10 @@ __enable_mmu:
msr ttbr0_el1, x25 // load TTBR0
msr ttbr1_el1, x26 // load TTBR1
isb
b __turn_mmu_on
ENDPROC(__enable_mmu)
/*
* Enable the MMU. This completely changes the structure of the visible memory
* space. You will not be able to trace execution through this.
*
* x0 = system control register
* x27 = *virtual* address to jump to upon completion
*
* other registers depend on the function called upon completion
*
* We align the entire function to the smallest power of two larger than it to
* ensure it fits within a single block map entry. Otherwise were PHYS_OFFSET
* close to the end of a 512MB or 1GB block we might require an additional
* table to map the entire function.
*/
.align 4
__turn_mmu_on:
msr sctlr_el1, x0
isb
br x27
ENDPROC(__turn_mmu_on)
ENDPROC(__enable_mmu)
/*
* Calculate the start of physical memory.