From e4193c7e92ab5213ecd536f048497b6546eab23c Mon Sep 17 00:00:00 2001
From: Will Deacon <will.deacon@arm.com>
Date: Tue, 14 Nov 2017 13:58:08 +0000
Subject: [PATCH 12/51] arm64: mm: Add arm64_kernel_unmapped_at_el0 helper

Git-commit: fc0e1299da548b32440051f58f08e0c1eb7edd0b
Patch-mainline: v4.16-rc1
References: bsc#1068032

In order for code such as TLB invalidation to operate efficiently when
the decision to map the kernel at EL0 is determined at runtime, this
patch introduces a helper function, arm64_kernel_unmapped_at_el0, to
determine whether or not the kernel is mapped whilst running in userspace.

Currently, this just reports the value of CONFIG_UNMAP_KERNEL_AT_EL0,
but will later be hooked up to a fake CPU capability using a static key.

Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Tested-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@suse.com>
---
 arch/arm64/include/asm/mmu.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
index 9751438cb991..6762f37457bd 100644
--- a/arch/arm64/include/asm/mmu.h
+++ b/arch/arm64/include/asm/mmu.h
@@ -18,6 +18,8 @@
 
 #define USER_ASID_FLAG	(UL(1) << 48)
 
+#ifndef __ASSEMBLY__
+
 typedef struct {
 	atomic64_t	id;
 	void		*vdso;
@@ -31,6 +33,11 @@ typedef struct {
  */
 #define ASID(mm)	((mm)->context.id.counter & 0xffff)
 
+static inline bool arm64_kernel_unmapped_at_el0(void)
+{
+	return IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0);
+}
+
 extern void paging_init(void);
 extern void bootmem_init(void);
 extern void __iomem *early_io_map(phys_addr_t phys, unsigned long virt);
@@ -41,4 +48,5 @@ extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
 extern void *fixmap_remap_fdt(phys_addr_t dt_phys);
 extern void mark_linear_text_alias_ro(void);
 
+#endif	/* !__ASSEMBLY__ */
 #endif
-- 
2.11.0