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>
This adds ARM support to BaseMemoryLibOptDxe, partially based on the
cortex-strings library (ScanMem) and the existing CopyMem() implementation
from BaseMemoryLibStm in ArmPkg.
All string routines are accelerated except ScanMem16, ScanMem32,
ScanMem64 and IsZeroBuffer, which can wait for another day. (Very few
occurrences exist in the codebase)
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