Arch arm assembly simplifications #19794
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
ARM user space requires ARM_MPU. We can, therefore, remove the unnecessary #ifdef CONFIG_ARM_MPU blocks in userspace.S. In addition, we do minor refactoring in z_arm_userspace_enter(), and z_arm_pendsv(), and z_arm_svc(), aiming at reducing the push/pop overhead as much as possible. Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>
agansari
suggested changes
Oct 14, 2019
arch/arm/core/swap_helper.S
Outdated
| @@ -427,7 +427,7 @@ SECTION_FUNC(TEXT, z_arm_svc) | |||
|
|
|||
| ldr r1, [r0, #24] /* grab address of PC from stack frame */ | |||
| /* SVC is a two-byte instruction, point to it and read encoding */ | |||
There was a problem hiding this comment.
change this comment to reference reading the lower byte of SVC
There was a problem hiding this comment.
Right, thanks. Fixed now
Add more documentation and inline explanatory comments in assembly sources swap_helper.S and userspace.S and remove redundant/wrong documentation when applicable. Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>
Some assembly simplifications, to make code common for ARMv6 and ARMv7 architecture. We can use ldrb, directly for reading the SVC encoding; this removes the need for ANDing the result with 0xff right below. We remove an immediate value of 0 from an str instruction, as it's redundant. Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>
ioannisg
force-pushed
the
arch_arm_assembly_simplifications
branch
from
877dc98 to
5029e44
Compare
agansari
approved these changes
Oct 14, 2019
wentongwu
approved these changes
Oct 14, 2019
11 tasks
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Preliminaries for #19689