• Suzuki K. Poulose's avatar
    arm64: Emulate SETEND for AArch32 tasks · 2d888f48
    Suzuki K. Poulose authored
    Emulate deprecated 'setend' instruction for AArch32 bit tasks.
    
    	setend [le/be] - Sets the endianness of EL0
    
    On systems with CPUs which support mixed endian at EL0, the hardware
    support for the instruction can be enabled by setting the SCTLR_EL1.SED
    bit. Like the other emulated instructions it is controlled by an entry in
    /proc/sys/abi/. For more information see :
    	Documentation/arm64/legacy_instructions.txt
    
    The instruction is emulated by setting/clearing the SPSR_EL1.E bit, which
    will be reflected in the PSTATE.E in AArch32 context.
    
    This patch also restores the native endianness for the execution of signal
    handlers, since the process could have changed the endianness.
    
    Note: All CPUs on the system must have mixed endian support at EL0. Once the
    handler is registered, hotplugging a CPU which doesn't support mixed endian,
    could lead to unexpected results/behavior in applications.
    Signed-off-by: 's avatarSuzuki K. Poulose <suzuki.poulose@arm.com>
    Cc: Will Deacon <will.deacon@arm.com>
    Cc: Punit Agrawal <punit.agrawal@arm.com>
    Signed-off-by: 's avatarCatalin Marinas <catalin.marinas@arm.com>
    2d888f48