Description: powerpc/tm: Fix oops on sigreturn on systems without TM
References:
 https://patchwork.ozlabs.org/patch/1133904/
 https://www.openwall.com/lists/oss-security/2019/07/30/1
Notes:
 bwh> We have disabled CONFIG_PPC_TRANSACTIONAL_MEM in 4.9.184-1 for
 bwh> other reasons, which I think will also fix this.
Bugs:
upstream: released (5.3-rc2) [f16d80b75a096c52354c6e0a574993f3b0dfbdfe]
4.19-upstream-stable: released (4.19.63) [b993a66d8ddc1c26da0d9aa3471789cc170b28ee]
4.9-upstream-stable: released (4.9.187) [08ee34d86c9c6a9b93c0986d7fc6e272690e8d24]
3.16-upstream-stable: released (3.16.72) [929606ae749185c940a5476d3a0e8d8e7c9c1db6]
sid: released (5.2.6-1)
4.19-buster-security: released (4.19.37-5+deb10u2) [bugfix/powerpc/powerpc-tm-Fix-oops-on-sigreturn-on-systems-without-TM.patch]
4.9-stretch-security: released (4.9.168-1+deb9u5) [bugfix/powerpc/powerpc-tm-fix-oops-on-sigreturn-on-systems-without-.patch]
3.16-jessie-security: ignored "powerpc not supported in LTS"