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Subject[PATCH 04/29] arm64: mm: Add arm64_kernel_unmapped_at_el0 helper
Date
From: Will Deacon <will.deacon@arm.com>

commit fc0e1299da54 upstream.

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: Alex Shi <alex.shi@linaro.org>
---
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 49924e5..279e75b 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;
@@ -30,6 +32,11 @@ 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);
@@ -39,4 +46,5 @@ extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
pgprot_t prot, bool allow_block_mappings);
extern void *fixmap_remap_fdt(phys_addr_t dt_phys);

+#endif /* !__ASSEMBLY__ */
#endif
--
2.7.4
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