84e000b88e
In the arm64 exception handler in libpayload, we use the banked exception stack pointer (SP_EL2, as opposed to the normal SP_EL0) not as a normal stack pointer, but simply as a pointer to the exception_state struct. This makes it easy to dump all registers into that struct on context switch. We then immediately switch back to SP_EL0. Yet, even though it is not really a stack for us, the aarch64 architecture still requires that SP_EL2 is 16 byte aligned at function boundaries. If the exception_state struct is not thus aligned, exceptions are broken. (I don't know why nobody ever hit this before, but I hit it now while trying to pull in zstd code. I guess we just don't have unaligned BSS entries that often and simply got lucky for a while. 3 hours wasted on debugging. :( ) Change-Id: Id19184656fb9da68fe4bfdbc240c0c25b9d24cd6 Signed-off-by: Julius Werner <jwerner@chromium.org> Reviewed-on: https://review.coreboot.org/c/coreboot/+/89926 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Yu-Ping Wu <yupingso@google.com> |
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