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Borislav Petkov authored
This is based on a patch originally by hpa. With the current improvements to the alternatives, we can simply use %P1 as a mem8 operand constraint and rely on the toolchain to generate the proper instruction sizes. For example, on 32-bit, where we use an empty old instruction we get: apply_alternatives: feat: 6*32+8, old: (c104648b, len: 4), repl: (c195566c, len: 4) c104648b: alt_insn: 90 90 90 90 c195566c: rpl_insn: 0f 0d 4b 5c ... apply_alternatives: feat: 6*32+8, old: (c18e09b4, len: 3), repl: (c1955948, len: 3) c18e09b4: alt_insn: 90 90 90 c1955948: rpl_insn: 0f 0d 08 ... apply_alternatives: feat: 6*32+8, old: (c1190cf9, len: 7), repl: (c1955a79, len: 7) c1190cf9: alt_insn: 90 90 90 90 90 90 90 c1955a79: rpl_insn: 0f 0d 0d a0 d4 85 c1 all with the proper padding done depending on the size of the replacement instruction the compiler generates. Signed-off-by:
Borislav Petkov <bp@suse.de> Cc: H. Peter Anvin <hpa@linux.intel.com>
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