powerpc: align syscall table for ppc32

Christophe Leroy reported that commit 7b45371 ("kbuild: link
symbol CRCs at final link,  removing CONFIG_MODULE_REL_CRCS") broke
mpc85xx_defconfig + CONFIG_RELOCATABLE=y.

    LD      vmlinux
    SYSMAP  System.map
    SORTTAB vmlinux
    CHKREL  vmlinux
  WARNING: 451 bad relocations
  c0b312a9 R_PPC_UADDR32     .head.text-0x3ff9ed54
  c0b312ad R_PPC_UADDR32     .head.text-0x3ffac224
  c0b312b1 R_PPC_UADDR32     .head.text-0x3ffb09f4
  c0b312b5 R_PPC_UADDR32     .head.text-0x3fe184dc
  c0b312b9 R_PPC_UADDR32     .head.text-0x3fe183a8
      ...

The compiler emits a bunch of R_PPC_UADDR32, which is not supported by
arch/powerpc/kernel/reloc_32.S.

The reason is there exists an unaligned symbol.

  $ powerpc-linux-gnu-nm -n vmlinux
    ...
  c0b31258 d spe_aligninfo
  c0b31298 d __func__.0
  c0b312a9 D sys_call_table
  c0b319b8 d __func__.0

Commit 7b45371 is not the root cause. Even before that, I can
reproduce the same issue for mpc85xx_defconfig + CONFIG_RELOCATABLE=y
+ CONFIG_MODVERSIONS=n.

It is just that nobody noticed because when CONFIG_MODVERSIONS is
enabled, a __crc_* symbol inserted before sys_call_table was hiding the
unalignment issue.

Adding alignment to the syscall table for ppc32 fixes the issue.

Cc: [email protected]
Reported-by: Christophe Leroy <[email protected]>
Signed-off-by: Masahiro Yamada <[email protected]>
Tested-by: Christophe Leroy <[email protected]>
[mpe: Trim change log discussion, add Cc stable]
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/lkml/[email protected]/
Link: https://lore.kernel.org/r/[email protected]

Author: masahir0y

arch/powerpc/kernel/systbl.S

@@ -18,6 +18,7 @@
 	.p2align	3
 #define __SYSCALL(nr, entry)	.8byte entry
 #else
+	.p2align	2
 #define __SYSCALL(nr, entry)	.long entry
 #endif