On Tue, 8 Sep 2020 22:58:50 +1000, Michael Ellerman wrote:

When we added the VDSO32 kconfig symbol, which controls building of
the 32-bit VDSO, we made it depend on CPU_BIG_ENDIAN (for 64-bit).

That was because back then COMPAT was always enabled for 64-bit, so
depending on it would have left the 32-bit VDSO always enabled, which
we didn't want.

[...]

Applied to powerpc/next.

[1/1] powerpc/64: Make VDSO32 track COMPAT on 64-bit
      https://git.kernel.org/powerpc/c/231b232df8f67e7d37af01259c21f2a131c3911e

cheers