diff options
Diffstat (limited to 'arch/powerpc/kernel/idle_book3s.S')
| -rw-r--r-- | arch/powerpc/kernel/idle_book3s.S | 20 |
1 files changed, 17 insertions, 3 deletions
diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S index 72dac0b58061..b350ac5e3111 100644 --- a/arch/powerpc/kernel/idle_book3s.S +++ b/arch/powerpc/kernel/idle_book3s.S @@ -439,9 +439,23 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300) _GLOBAL(pnv_wakeup_tb_loss) ld r1,PACAR1(r13) /* - * Before entering any idle state, the NVGPRs are saved in the stack - * and they are restored before switching to the process context. Hence - * until they are restored, they are free to be used. + * Before entering any idle state, the NVGPRs are saved in the stack. + * If there was a state loss, or PACA_NAPSTATELOST was set, then the + * NVGPRs are restored. If we are here, it is likely that state is lost, + * but not guaranteed -- neither ISA207 nor ISA300 tests to reach + * here are the same as the test to restore NVGPRS: + * PACA_THREAD_IDLE_STATE test for ISA207, PSSCR test for ISA300, + * and SRR1 test for restoring NVGPRs. + * + * We are about to clobber NVGPRs now, so set NAPSTATELOST to + * guarantee they will always be restored. This might be tightened + * with careful reading of specs (particularly for ISA300) but this + * is already a slow wakeup path and it's simpler to be safe. + */ + li r0,1 + stb r0,PACA_NAPSTATELOST(r13) + + /* * * Save SRR1 and LR in NVGPRs as they might be clobbered in * opal_call() (called in CHECK_HMI_INTERRUPT). SRR1 is required |