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Konrad Rzeszutek Wilk
67af3e52f4
The NOP functionality will NOP any of the code at the 'old_addr' or at 'name' if the 'new_addr' is zero. The purpose of this is to NOP out calls, such as: e8 <4-bytes-offset> (5 byte insn), or on ARM a 4 byte insn for branching. We need the EIP of where we need to the NOP, and that can be provided via the `old_addr` or `name`. If the `old_addr` is provided we will NOP 'new_size' amount of bytes at that location. The amount is up to 31 instructions if desired (which is the size of the opaque member). If there is a need to NOP more then: a) more 'struct livepatch_func' structures need to be present, b) we have to implement a variable size buffer (in the future), or c) first byte an unconditional branch skipping the to be disabled code (of course provided there are no branch targets in the middle). While at it, also unify the code on x86 patching so it is a bit simpler (instead of two seperate writes just make it one memcpy). And introduce a general livepatch_insn_len inline function that would depend on platform specific instruction size (for a unconditional branch). As such we also rename the PATCH_INSN_SIZE to ARCH_PATCH_INSN_SIZE. Reviewed-by: Jan Beulich <jbeulich@suse.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>