Issue DSB; ISB after changing FPU status to ensure completion #43
Conversation
This file contains hidden or 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
Member
Could you add a comment with a link to the documentation that states this? Are these instructions also required when disabling the FPU? If so, shouldn't they be called before disabling the FPU? Wondering if the pipeline may execute the CPACR write while some floating point op is in progress or something like that. |
Contributor
Author
|
Actually now that I look again, Cortex-M4 TRM does not say that DSB/ISB are required: |
adamgreig
pushed a commit
that referenced
this pull request
Jan 12, 2022
Zero cost stack overflow protection, take 2
adamgreig
pushed a commit
that referenced
this pull request
Jan 12, 2022
this commit adds LLD support by removing all INFO sections. LLD kind of supports INFO in the form of NOLOAD but when the linker script contains NOLOAD sections LLD emits a binary with false `size` information: for example, it reported a fake increase of 20KB in .text and a fake increase of 1KB in .bss when compiling a program that only allocates a single Box. As the INFO sections are gone we can no longer support the stack overflow protection added in #43 so all the other related changes, like making _stack_start overridable, have been removed as well. If you want to continue using stack overflow protection you can stick to v0.3.x. As the .debug_gdb_scripts output section has been removed from the linker script these changes will only reliably support both LD and LLD if/when rust-lang/rust#49728 lands. closes #53
reitermarkus
pushed a commit
to reitermarkus/cortex-m
that referenced
this pull request
May 4, 2022
this commit adds LLD support by removing all INFO sections. LLD kind of supports INFO in the form of NOLOAD but when the linker script contains NOLOAD sections LLD emits a binary with false `size` information: for example, it reported a fake increase of 20KB in .text and a fake increase of 1KB in .bss when compiling a program that only allocates a single Box. As the INFO sections are gone we can no longer support the stack overflow protection added in rust-embedded#43 so all the other related changes, like making _stack_start overridable, have been removed as well. If you want to continue using stack overflow protection you can stick to v0.3.x. As the .debug_gdb_scripts output section has been removed from the linker script these changes will only reliably support both LD and LLD if/when rust-lang/rust#49728 lands. closes rust-embedded#53
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
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.
This is necessary according to ARM, I suppose if some VFP op got scheduled right after an inlined FPU enable it would be trouble.