[PATCH v5 6/8] arm64: merge __enable_mmu and __turn_mmu_on
ard.biesheuvel at linaro.org
Wed Mar 18 07:55:25 PDT 2015
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
Also replaces an open coded adrp/add reference to __enable_mmu with
Reviewed-by: Mark Rutland <mark.rutland at arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
arch/arm64/kernel/head.S | 33 +++++++--------------------------
1 file changed, 7 insertions(+), 26 deletions(-)
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 65c7de889c8c..9a2554558e5b 100644
@@ -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
@@ -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
ldr x5, =vectors
@@ -627,29 +627,10 @@ __enable_mmu:
msr ttbr0_el1, x25 // load TTBR0
msr ttbr1_el1, x26 // load TTBR1
- b __turn_mmu_on
- * 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
msr sctlr_el1, x0
* Calculate the start of physical memory.
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