arm64: mm: add code to safely replace TTBR1_EL1

[cascardo/linux.git] / arch / arm64 / include / asm / mmu_context.h

diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index 944f273..a00f7cf 100644 (file)
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -126,6 +126,25 @@ static inline void cpu_install_idmap(void)
        cpu_switch_mm(idmap_pg_dir, &init_mm);
 }
 
+/*
+ * Atomically replaces the active TTBR1_EL1 PGD with a new VA-compatible PGD,
+ * avoiding the possibility of conflicting TLB entries being allocated.
+ */
+static inline void cpu_replace_ttbr1(pgd_t *pgd)
+{
+       typedef void (ttbr_replace_func)(phys_addr_t);
+       extern ttbr_replace_func idmap_cpu_replace_ttbr1;
+       ttbr_replace_func *replace_phys;
+
+       phys_addr_t pgd_phys = virt_to_phys(pgd);
+
+       replace_phys = (void *)virt_to_phys(idmap_cpu_replace_ttbr1);
+
+       cpu_install_idmap();
+       replace_phys(pgd_phys);
+       cpu_uninstall_idmap();
+}
+
 /*
  * It would be nice to return ASIDs back to the allocator, but unfortunately
  * that introduces a race with a generation rollover where we could erroneously