From: ard.biesheuvel@linaro.org (Ard Biesheuvel)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 5/9] arm64: kernel: use x30 for __enable_mmu return address
Date: Wed, 24 Aug 2016 16:36:02 +0200 [thread overview]
Message-ID: <1472049366-10922-6-git-send-email-ard.biesheuvel@linaro.org> (raw)
In-Reply-To: <1472049366-10922-1-git-send-email-ard.biesheuvel@linaro.org>
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 <ard.biesheuvel@linaro.org>
---
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
next prev parent reply other threads:[~2016-08-24 14:36 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-24 14:35 [PATCH v2 0/9] arm64: clean up early boot function calls Ard Biesheuvel
2016-08-24 14:35 ` [PATCH v2 1/9] arm64: kernel: get rid of x25 and x26 with 'global' scope Ard Biesheuvel
2016-08-24 14:35 ` [PATCH v2 2/9] arm64: kernel: fix style issues in sleep.S Ard Biesheuvel
2016-08-24 16:13 ` Mark Rutland
2016-08-24 14:36 ` [PATCH v2 3/9] arm64: kernel: use ordinary return/argument register for el2_setup() Ard Biesheuvel
2016-08-24 16:20 ` Mark Rutland
2016-08-24 14:36 ` [PATCH v2 4/9] arm64: head.S: move KASLR processing out of __enable_mmu() Ard Biesheuvel
2016-08-24 20:36 ` Mark Rutland
2016-08-24 20:44 ` Ard Biesheuvel
2016-08-24 20:46 ` Mark Rutland
2016-08-25 13:59 ` Ard Biesheuvel
2016-08-30 10:24 ` Mark Rutland
2016-08-30 13:45 ` Mark Rutland
2016-08-24 14:36 ` Ard Biesheuvel [this message]
2016-08-24 14:36 ` [PATCH v2 6/9] arm64: call __enable_mmu as an ordinary function for secondary/resume Ard Biesheuvel
2016-08-30 14:07 ` Mark Rutland
2016-08-24 14:36 ` [PATCH v2 7/9] arm64: kernel: drop use of x24 from primary boot path Ard Biesheuvel
2016-08-30 14:26 ` Mark Rutland
2016-08-24 14:36 ` [PATCH v2 8/9] arm64: head.S: use ordinary stack frame for __primary_switched() Ard Biesheuvel
2016-08-30 14:38 ` Mark Rutland
2016-08-24 14:36 ` [PATCH v2 9/9] arm64: head.S: document the use of callee saved registers Ard Biesheuvel
2016-08-30 14:43 ` Mark Rutland
2016-08-30 14:48 ` [PATCH v2 0/9] arm64: clean up early boot function calls Mark Rutland
2016-08-30 14:50 ` Ard Biesheuvel
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