[PATCH v2 5/9] arm64: kernel: use x30 for __enable_mmu return address
From: Ard Biesheuvel <hidden>
Date: 2016-08-24 14:36:02
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
Using x27 for passing to __enable_mmu what is essentially the return address makes the code look more complicated than it needs to be. So in preparation of further simplifications, switch to x30/lr. Signed-off-by: Ard Biesheuvel <redacted> --- arch/arm64/kernel/head.S | 12 +++++------- arch/arm64/kernel/sleep.S | 2 +- 2 files changed, 6 insertions(+), 8 deletions(-)
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index d390feb92730..3e08e51578d5 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S@@ -664,7 +664,7 @@ secondary_startup: */ bl __cpu_setup // initialise processor - adr_l x27, __secondary_switch // address to jump to after enabling the MMU + adr_l lr, __secondary_switch // address to jump to after enabling the MMU b __enable_mmu ENDPROC(secondary_startup)
@@ -710,9 +710,9 @@ ENTRY(__early_cpu_boot_status) * Enable 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. + * Returns to the caller via x30/lr. This requires the caller to be covered + * by the .idmap.text section. * * Checks if the selected granule size is supported by the CPU. * If it isn't, park the CPU
@@ -739,7 +739,7 @@ ENTRY(__enable_mmu) ic iallu dsb nsh isb - br x27 + ret ENDPROC(__enable_mmu) __no_granule_support:
@@ -784,9 +784,7 @@ __primary_switch: mrs x20, sctlr_el1 // preserve old SCTLR_EL1 value #endif - adr x27, 0f - b __enable_mmu -0: + bl __enable_mmu #ifdef CONFIG_RELOCATABLE bl __relocate_kernel #ifdef CONFIG_RANDOMIZE_BASE
diff --git a/arch/arm64/kernel/sleep.S b/arch/arm64/kernel/sleep.S
index bbc63099223b..4bce95cd656a 100644
--- a/arch/arm64/kernel/sleep.S
+++ b/arch/arm64/kernel/sleep.S@@ -99,7 +99,7 @@ ENTRY(cpu_resume) bl el2_setup // if in EL2 drop to EL1 cleanly bl __cpu_setup /* enable the MMU early - so we can access sleep_save_stash by va */ - adr_l x27, _resume_switched /* __enable_mmu will branch here */ + adr_l lr, _resume_switched /* __enable_mmu will branch here */ b __enable_mmu ENDPROC(cpu_resume)
--
2.7.4