arm64: mm: provide idmap pointer to cpu_replace_ttbr1()

In preparation for changing the way we initialize the permanent ID map,
update cpu_replace_ttbr1() so we can use it with the initial ID map as
well.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220624150651.1358849-11-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

arch/arm64/include/asm/mmu_context.h

@@ -105,13 +105,18 @@ static inline void cpu_uninstall_idmap(void)
 		cpu_switch_mm(mm->pgd, mm);
 }
 
-static inline void cpu_install_idmap(void)
+static inline void __cpu_install_idmap(pgd_t *idmap)
 {
 	cpu_set_reserved_ttbr0();
 	local_flush_tlb_all();
 	cpu_set_idmap_tcr_t0sz();
 
-	cpu_switch_mm(lm_alias(idmap_pg_dir), &init_mm);
+	cpu_switch_mm(lm_alias(idmap), &init_mm);
+}
+
+static inline void cpu_install_idmap(void)
+{
+	__cpu_install_idmap(idmap_pg_dir);
 }
 
 /*
@@ -142,7 +147,7 @@ static inline void cpu_install_ttbr0(phys_addr_t ttbr0, unsigned long t0sz)
  * 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 __nocfi cpu_replace_ttbr1(pgd_t *pgdp)
+static inline void __nocfi cpu_replace_ttbr1(pgd_t *pgdp, pgd_t *idmap)
 {
 	typedef void (ttbr_replace_func)(phys_addr_t);
 	extern ttbr_replace_func idmap_cpu_replace_ttbr1;
@@ -165,7 +170,7 @@ static inline void __nocfi cpu_replace_ttbr1(pgd_t *pgdp)
 
 	replace_phys = (void *)__pa_symbol(function_nocfi(idmap_cpu_replace_ttbr1));
 
-	cpu_install_idmap();
+	__cpu_install_idmap(idmap);
 	replace_phys(ttbr1);
 	cpu_uninstall_idmap();
 }

arch/arm64/kernel/cpufeature.c

@@ -3218,7 +3218,7 @@ subsys_initcall_sync(init_32bit_el0_mask);
 
 static void __maybe_unused cpu_enable_cnp(struct arm64_cpu_capabilities const *cap)
 {
-	cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
+	cpu_replace_ttbr1(lm_alias(swapper_pg_dir), idmap_pg_dir);
 }
 
 /*

arch/arm64/kernel/suspend.c

@@ -52,7 +52,7 @@ void notrace __cpu_suspend_exit(void)
 
 	/* Restore CnP bit in TTBR1_EL1 */
 	if (system_supports_cnp())
-		cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
+		cpu_replace_ttbr1(lm_alias(swapper_pg_dir), idmap_pg_dir);
 
 	/*
 	 * PSTATE was not saved over suspend/resume, re-enable any detected

arch/arm64/mm/kasan_init.c

@@ -236,7 +236,7 @@ static void __init kasan_init_shadow(void)
 	 */
 	memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir));
 	dsb(ishst);
-	cpu_replace_ttbr1(lm_alias(tmp_pg_dir));
+	cpu_replace_ttbr1(lm_alias(tmp_pg_dir), idmap_pg_dir);
 
 	clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
 
@@ -280,7 +280,7 @@ static void __init kasan_init_shadow(void)
 				PAGE_KERNEL_RO));
 
 	memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE);
-	cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
+	cpu_replace_ttbr1(lm_alias(swapper_pg_dir), idmap_pg_dir);
 }
 
 static void __init kasan_init_depth(void)

arch/arm64/mm/mmu.c

@@ -777,7 +777,7 @@ void __init paging_init(void)
 
 	pgd_clear_fixmap();
 
-	cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
+	cpu_replace_ttbr1(lm_alias(swapper_pg_dir), idmap_pg_dir);
 	init_mm.pgd = swapper_pg_dir;
 
 	memblock_phys_free(__pa_symbol(init_pg_dir),