[PATCH 22/52] arm64: Move post_ttbr_update_workaround to C code

[Alex Shi]

From: Marc Zyngier <marc.zyngier@xxxxxxx>

commit 95e3de3590e3 upstream.

We will soon need to invoke a CPU-specific function pointer after changing
page tables, so move post_ttbr_update_workaround out into C code to make
this possible.

Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Alex Shi <alex.shi@xxxxxxxxxx>

Conflicts:
	don't include PAN related changes
	arch/arm64/include/asm/assembler.h
	arch/arm64/kernel/entry.S
	arch/arm64/mm/proc.S
---
 arch/arm64/mm/context.c | 9 +++++++++
 arch/arm64/mm/proc.S    | 3 +--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c
index efcf1f7..32eeabe91 100644
--- a/arch/arm64/mm/context.c
+++ b/arch/arm64/mm/context.c
@@ -224,6 +224,15 @@ void check_and_switch_context(struct mm_struct *mm, unsigned int cpu)
 	cpu_switch_mm(mm->pgd, mm);
 }
 
+/* Errata workaround post TTBRx_EL1 update. */
+asmlinkage void post_ttbr_update_workaround(void)
+{
+	asm(ALTERNATIVE("nop; nop; nop",
+			"ic iallu; dsb nsh; isb",
+			ARM64_WORKAROUND_CAVIUM_27456,
+			CONFIG_CAVIUM_ERRATUM_27456));
+}
+
 static int asids_init(void)
 {
 	asid_bits = get_cpu_asid_bits();
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index c2adb0c..cca061a 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -136,8 +136,7 @@ ENTRY(cpu_do_switch_mm)
 	bfi	x0, x1, #48, #16		// set the ASID
 	msr	ttbr0_el1, x0			// set TTBR0
 	isb
-	post_ttbr0_update_workaround
-	ret
+	b	post_ttbr_update_workaround	// Back to C code...
 ENDPROC(cpu_do_switch_mm)
 
 	.pushsection ".idmap.text", "ax"
-- 
2.7.4