ARM uses the low order bit of a branch target address to decide in
which execution mode (ARM or Thumb) a function needs to be called.
In order for this to work across object files, ELF function symbols
will have the low bit set if they were emitted in Thumb mode and
cleared otherwise. This annotation is only emitted if the ELF symbols
are annotated as function, since taking the address of some data
symbol (e.g., a literal) should not produce a value with the low bit
set, even if it appears in an object file containing Thumb code.
This means that all functions coded in assembler must have this
function annotation, or they may end up getting called in the
wrong mode, crashing the program.
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
Reviewed-by: Liming Gao <liming.gao@intel.com>
The ARM architecture version 8 deprecates all uses of the IT instruction
except cases where it is followed by a single narrow instruction. So
replace any occurrences with equivalent sequences that adhere to the
new rules.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Liming Gao <liming.gao@intel.com>
As reported by Vishal, CompareGuid() is a hotspot, and switching from
BaseMemoryLibStm in ArmPkg/ to BaseMemoryLibOptDxe causes a noticeable
performance regression due to the fact that BaseMemoryLibOptDxe uses
unaligned accessors explicitly to implement CompareGuid() and the related
functions.
Since BaseMemoryLibOptDxe on ARM and AARCH64 can only be used in contexts
where unaligned accesses are allowed, reimplement these functions for ARM
and AARCH64 specifically, using wide accessors that can tolerate any
misalignment.
Reported-by: "Oliyil Kunnil, Vishal" <vishalo@qti.qualcomm.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Michael D Kinney
Ard Biesheuvel