Issue DSB; ISB after changing FPU status to ensure completion #43
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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. |
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Actually now that I look again, Cortex-M4 TRM does not say that DSB/ISB are required: |
adamgreig
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Jan 12, 2022
Zero cost stack overflow protection, take 2
adamgreig
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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
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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
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This is necessary according to ARM, I suppose if some VFP op got scheduled right after an inlined FPU enable it would be trouble.