diff options
| author | Gautham R. Shenoy | 2018-07-18 14:03:16 +0530 |
|---|---|---|
| committer | Michael Ellerman | 2018-07-18 20:40:17 +1000 |
| commit | b03897cf318dfc47de33a7ecbc7655584266f034 (patch) | |
| tree | 4e333d4a50a428b4f7b01dc478487d22b630ad96 | |
| parent | 4e4a4b75ccce827f9b8b04b6ee5c90169df4b6ee (diff) | |
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>
| -rw-r--r-- | arch/powerpc/kernel/idle_book3s.S | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S index e734f6e45abc..689306118b48 100644 --- a/arch/powerpc/kernel/idle_book3s.S +++ b/arch/powerpc/kernel/idle_book3s.S @@ -144,7 +144,9 @@ power9_restore_additional_sprs: mtspr SPRN_MMCR1, r4 ld r3, STOP_MMCR2(r13) + ld r4, PACA_SPRG_VDSO(r13) mtspr SPRN_MMCR2, r3 + mtspr SPRN_SPRG3, r4 blr /* |