On AARCH64, before we turn on the MMU, unaligned accesses are not allowed.
Since the idiom recognition employed by GCC may turn allowable sequences
into sequences that result in such unaligned accesses (i.e., a sequence of
byte wide loads in reverse order may be turned into a wider load and a rev
instruction of the compiler thinks unaligned accesses are allowed), we have
to make sure that any code that may execute before the MMU is enabled is
built with -mstrict-align.
Since this aligns with the notion of XIP we have in EDK2, let's add a build
rule that allows XIP specific CC option overrides to be set, and use it to
set the -mstrict-align CC flag for BASE, SEC, PEI_CORE and PEIM modules.
(XIPFLAGS has been suggest by Andrew Fish a couple of months ago, when a
similar issue came up)
Ard Biesheuvel (2):
BaseTools: add separate build rule for modules that may execute in
place
BaseTools AARCH64: build XIP modules with strict alignment
BaseTools/Conf/build_rule.template | 26 ++++++++++++++++++++
BaseTools/Conf/tools_def.template | 9 ++++++-
2 files changed, 34 insertions(+), 1 deletion(-)
--
2.5.0
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