fix alignment exception for ullPortInterruptNesting. #317
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While loading (LDR X5, ullPortInterruptNestingConst) the ullPortInterruptNesting variable, the program control seems to be stuck and there is no abort or stack trace observed (as there is no exception handler is installed to catch unaligned access exception). Program control moves forward, if one just declares this varible to be 2 bytes aligned but then varible is not updated properly. One of my colleague, pointed out that issue is due to the fact that ullPortInterruptNesting must be at 8 bytes aligned address but since "vApplicationIRQHandler" (that has 4 bytes of address) is sitting between two 8 bytes aligned addresses that forces ullPortInterruptNesting to be at 4 byte aligned address, causing all sort of mess. It works on QEMU (on ARM64) as it is, since there is no such check for unaligned access but on real hardware it is prohibited. Workaround to this problem is, either we skip 4 byets (using .align 4) after vApplicationIRQHandler declaration or declare it the end of all declarations. This commit does the latter one. Signed-off-by: Amit Singh Tomar <atomar25opensource@gmail.com>
RichardBarry
previously approved these changes
May 5, 2021
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n9wxu
approved these changes
Dec 29, 2021
ravibhagavandas
approved these changes
Dec 29, 2021
laroche
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Apr 18, 2024
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While loading (LDR X5, ullPortInterruptNestingConst) the ullPortInterruptNesting
variable, the program control seems to be stuck and there is no abort or stack
trace observed (as there is no exception handler is installed to catch unaligned
access exception).
Program control moves forward, if one just declares this varible to be 2 bytes
aligned but then varible is not updated properly.
One of my colleague, pointed out that issue is due to the fact that
ullPortInterruptNesting must be at 8 bytes aligned address but since
"vApplicationIRQHandler" (that has 4 bytes of address) is sitting between
two 8 bytes aligned addresses that forces ullPortInterruptNesting to be at
4 byte aligned address, causing all sort of mess.
It works on QEMU (on ARM64) as it is, since there is no such check for
unaligned access but on real hardware it is prohibited.
Workaround to this problem is, either we skip 4 byets (using .align 4) after
vApplicationIRQHandler declaration or declare it the end of all declarations.
This commit does the latter one.
Signed-off-by: Amit Singh Tomar atomar25opensource@gmail.com
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