[S] Change in coreboot[main]: include/endian.h: Add 'always aligned access' support

[Maximilian Brune (Code Review)]

Attention is currently required from: Maximilian Brune.

Hello build bot (Jenkins),

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/86609?usp=email

to look at the new patch set (#3).

Change subject: include/endian.h: Add 'always aligned access' support
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include/endian.h: Add 'always aligned access' support

RISC-V doesn't support unaligned access, so check for that before
decoding and encoding. It is not perfectly performant, but still much
better then invoking the misaligned exception handler every time there
is a misaligned access. We can't modify our whole codebase to always do
aligned access, because it is neither feasible in long term nor is fair
to add that performance penalty onto other architectures that do support
unaligned access. So this is the next best thing.

On architectures that do support unaligned access the compiler will just
optimize the RISCV_ENV part out and should result in the exact same
binary.

tested: identical binary on QEMU-aarch64 and QEMU-q35.

Change-Id: I4dfccfdc2b302dd30b7ce5a29520c86add13169d
Signed-off-by: Maximilian Brune 
---
M src/include/endian.h
1 file changed, 25 insertions(+), 4 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/09/86609/3