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| author | Gautham R. Shenoy <ego@linux.vnet.ibm.com> | 2018-07-18 11:33:16 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2018-07-18 13:40:17 +0300 |
| commit | b03897cf318dfc47de33a7ecbc7655584266f034 (patch) | |
| tree | 4e333d4a50a428b4f7b01dc478487d22b630ad96 /drivers | |
| parent | 4e4a4b75ccce827f9b8b04b6ee5c90169df4b6ee (diff) | |
| download | linux-b03897cf318dfc47de33a7ecbc7655584266f034.tar.xz | |
powerpc/powernv: Fix save/restore of SPRG3 on entry/exit from stop (idle)
On 64-bit servers, SPRN_SPRG3 and its userspace read-only mirror
SPRN_USPRG3 are used as userspace VDSO write and read registers
respectively.
SPRN_SPRG3 is lost when we enter stop4 and above, and is currently not
restored. As a result, any read from SPRN_USPRG3 returns zero on an
exit from stop4 (Power9 only) and above.
Thus in this situation, on POWER9, any call from sched_getcpu() always
returns zero, as on powerpc, we call __kernel_getcpu() which relies
upon SPRN_USPRG3 to report the CPU and NUMA node information.
Fix this by restoring SPRN_SPRG3 on wake up from a deep stop state
with the sprg_vdso value that is cached in PACA.
Fixes: e1c1cfed5432 ("powerpc/powernv: Save/Restore additional SPRs for stop4 cpuidle")
Cc: stable@vger.kernel.org # v4.14+
Reported-by: Florian Weimer <fweimer@redhat.com>
Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Reviewed-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'drivers')
0 files changed, 0 insertions, 0 deletions