Description: powerpc: missing Spectre-RSB mitigation
References:
 https://www.openwall.com/lists/oss-security/2019/11/27/1
Notes:
 carnil> Technically (resp. from CVE assignment point of view) the CVE
 carnil> is solely for the missing Spectre-RSB mitigation and
 carnil> 39e72bf96f58 ("powerpc/book3s64: Fix link stack flush on
 carnil> context switch").
Bugs:
upstream: released (5.5-rc1) [39e72bf96f5847ba87cc5bd7a3ce0fed813dc9ad, af2e8c68b9c5403f77096969c516f742f5bb29e0]
4.19-upstream-stable: released (4.19.87) [0a60d4bddc0ba6a7e06d10efa59f7861837860b0, 345712c95eec44bf414782b33e6d5a550fe62b3b]
4.9-upstream-stable: released (4.9.204) [113408cdaec11a6e34d4edabb134a335dd4896b3, e2c87b1ba04bd5042f6db0780ed55abaf4836378]
3.16-upstream-stable: ignored "No speculation mitigations available for powerpc"
sid: released (5.3.15-1)
4.19-buster-security: released (4.19.87-1)
4.9-stretch-security: released (4.9.210-1)
3.16-jessie-security: ignored "powerpc not supported in LTS"