Fix built-in early-load Intel microcode alignment

BugLink: https://bugs.launchpad.net/bugs/1860681

commit f5ae2ea6 upstream.

Intel Software Developer's Manual, volume 3, chapter 9.11.6 says:

 "Note that the microcode update must be aligned on a 16-byte boundary
  and the size of the microcode update must be 1-KByte granular"

When early-load Intel microcode is loaded from initramfs, userspace tool
'iucode_tool' has already 16-byte aligned those microcode bits in that
initramfs image.  Image that was created something like this:

 iucode_tool --write-earlyfw=FOO.cpio microcode-files...

However, when early-load Intel microcode is loaded from built-in
firmware BLOB using CONFIG_EXTRA_FIRMWARE= kernel config option, that
16-byte alignment is not guaranteed.

Fix this by forcing all built-in firmware BLOBs to 16-byte alignment.

[ If we end up having other firmware with much bigger alignment
  requirements, we might need to introduce some method for the firmware
  to specify it, this is the minimal "just increase the alignment a bit
  to account for this one special case" patch    - Linus ]
Signed-off-by: Jari Ruusu <jari.ruusu@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

firmware/Makefile

@@ -76,7 +76,7 @@ quiet_cmd_fwbin = MK_FW   $@
 		  PROGBITS=$(if $(CONFIG_ARM),%,@)progbits;		     \
 		  echo "/* Generated by firmware/Makefile */"		> $@;\
 		  echo "    .section .rodata"				>>$@;\
-		  echo "    .p2align $${ASM_ALIGN}"			>>$@;\
+		  echo "    .p2align 4"					>>$@;\
 		  echo "_fw_$${FWSTR}_bin:"				>>$@;\
 		  echo "    .incbin \"$(2)\""				>>$@;\
 		  echo "_fw_end:"					>>$@;\