diff options
Diffstat (limited to 'arch/powerpc/kernel')
| -rw-r--r-- | arch/powerpc/kernel/syscall_64.c | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/arch/powerpc/kernel/syscall_64.c b/arch/powerpc/kernel/syscall_64.c index 613da0d0fa8c..79edba3ab312 100644 --- a/arch/powerpc/kernel/syscall_64.c +++ b/arch/powerpc/kernel/syscall_64.c @@ -242,6 +242,10 @@ notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs, unsigned BUG_ON(!FULL_REGS(regs)); BUG_ON(regs->softe != IRQS_ENABLED); + /* + * We don't need to restore AMR on the way back to userspace for KUAP. + * AMR can only have been unlocked if we interrupted the kernel. + */ kuap_check_amr(); local_irq_save(flags); @@ -313,13 +317,14 @@ notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs, unsign unsigned long *ti_flagsp = ¤t_thread_info()->flags; unsigned long flags; unsigned long ret = 0; + unsigned long amr; if (IS_ENABLED(CONFIG_PPC_BOOK3S) && unlikely(!(regs->msr & MSR_RI))) unrecoverable_exception(regs); BUG_ON(regs->msr & MSR_PR); BUG_ON(!FULL_REGS(regs)); - kuap_check_amr(); + amr = kuap_get_and_check_amr(); if (unlikely(*ti_flagsp & _TIF_EMULATE_STACK_STORE)) { clear_bits(_TIF_EMULATE_STACK_STORE, ti_flagsp); @@ -367,10 +372,11 @@ again: #endif /* - * We don't need to restore AMR on the way back to userspace for KUAP. - * The value of AMR only matters while we're in the kernel. + * Don't want to mfspr(SPRN_AMR) here, because this comes after mtmsr, + * which would cause Read-After-Write stalls. Hence, we take the AMR + * value from the check above. */ - kuap_restore_amr(regs); + kuap_restore_amr(regs, amr); return ret; } |