Merge "arm64: SW PAN: Point saved ttbr0 at the zero page when switching to init_mm" (493555de) · Commits · e / devices / android_kernel_fairphone_FP3

arch/arm64/include/asm/efi.h

+1 −3

Original line number	Diff line number	Diff line
		@@ -93,10 +93,8 @@ static inline void efi_set_pgd(struct mm_struct *mm)
		* Defer the switch to the current thread's TTBR0_EL1
		* until uaccess_enable(). Restore the current
		* thread's saved ttbr0 corresponding to its active_mm
		* (if different from init_mm).
		*/
		cpu_set_reserved_ttbr0();
		if (current->active_mm != &init_mm)
		update_saved_ttbr0(current, current->active_mm);
		}
		}

+13 −9

Original line number	Diff line number	Diff line
		@@ -174,11 +174,17 @@ enter_lazy_tlb(struct mm_struct mm, struct task_struct tsk)
		static inline void update_saved_ttbr0(struct task_struct *tsk,
		struct mm_struct *mm)
		{
		if (system_uses_ttbr0_pan()) {
		BUG_ON(mm->pgd == swapper_pg_dir);
		task_thread_info(tsk)->ttbr0 =
		virt_to_phys(mm->pgd) \| ASID(mm) << 48;
		}
		u64 ttbr;

		if (!system_uses_ttbr0_pan())
		return;

		if (mm == &init_mm)
		ttbr = __pa_symbol(empty_zero_page);
		else
		ttbr = virt_to_phys(mm->pgd) \| ASID(mm) << 48;

		task_thread_info(tsk)->ttbr0 = ttbr;
		}
		#else
		static inline void update_saved_ttbr0(struct task_struct *tsk,
		@@ -214,10 +220,8 @@ switch_mm(struct mm_struct prev, struct mm_struct next,
		* Update the saved TTBR0_EL1 of the scheduled-in task as the previous
		* value may have not been initialised yet (activate_mm caller) or the
		* ASID has changed since the last run (following the context switch
		* of another thread of the same process). Avoid setting the reserved
		* TTBR0_EL1 to swapper_pg_dir (init_mm; e.g. via idle_task_exit).
		* of another thread of the same process).
		*/
		if (next != &init_mm)
		update_saved_ttbr0(tsk, next);
		}