x86/tools: objdump_reformat.awk: Ensure regex matches fwait

If there is "wait" mnemonic in the line being parsed, it is incorrectly
handled by the script, and an extra line of "fwait" in
objdump_reformat's output is inserted. As insn_decoder_test relies upon
the formatted output, the test fails.

This is reproducible when disassembling with llvm-objdump:

Pre-processed lines:

  ffffffff81033e72: 9b                    wait
  ffffffff81033e73: 48 c7 c7 89 50 42 82  movq

After objdump_reformat.awk:

  ffffffff81033e72:       9b      fwait
  ffffffff81033e72:                               wait
  ffffffff81033e73:       48 c7 c7 89 50 42 82    movq

The regex match now accepts spaces or tabs, along with the "fwait"
instruction.

Signed-off-by: Samuel Zeter <samuelzeter@gmail.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20231129-objdump-reformat-llvm-v3-1-0d855e79314d@kernel.org
Closes: https://github.com/ClangBuiltLinux/linux/issues/1364

arch/x86/tools/objdump_reformat.awk

@@ -12,7 +12,7 @@ BEGIN {
 	prev_hex = ""
 	prev_mnemonic = ""
 	bad_expr = "(\\(bad\\)|^rex|^.byte|^rep(z|nz)$|^lock$|^es$|^cs$|^ss$|^ds$|^fs$|^gs$|^data(16|32)$|^addr(16|32|64))"
-	fwait_expr = "^9b "
+	fwait_expr = "^9b[ \t]*fwait"
 	fwait_str="9b\tfwait"
 }