arm64: Revert "mm: provide idmap pointer to cpu_replace_ttbr1()"

This reverts commit 1682c45b, which is no longer needed now that
we create the permanent kernel mapping directly during early boot.

This is a RINO (revert in name only) given that some of the code has
moved around, but the changes are straight-forward.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-69-ardb+git@google.comSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/include/asm/mmu_context.h

@@ -108,18 +108,13 @@ static inline void cpu_uninstall_idmap(void)
 		cpu_switch_mm(mm->pgd, mm);
 }
 
-static inline void __cpu_install_idmap(pgd_t *idmap)
+static inline void cpu_install_idmap(void)
 {
 	cpu_set_reserved_ttbr0();
 	local_flush_tlb_all();
 	cpu_set_idmap_tcr_t0sz();
 
-	cpu_switch_mm(lm_alias(idmap), &init_mm);
-}
-
-static inline void cpu_install_idmap(void)
-{
-	__cpu_install_idmap(idmap_pg_dir);
+	cpu_switch_mm(lm_alias(idmap_pg_dir), &init_mm);
 }
 
 /*
@@ -146,21 +141,21 @@ static inline void cpu_install_ttbr0(phys_addr_t ttbr0, unsigned long t0sz)
 	isb();
 }
 
-void __cpu_replace_ttbr1(pgd_t *pgdp, pgd_t *idmap, bool cnp);
+void __cpu_replace_ttbr1(pgd_t *pgdp, bool cnp);
 
 static inline void cpu_enable_swapper_cnp(void)
 {
-	__cpu_replace_ttbr1(lm_alias(swapper_pg_dir), idmap_pg_dir, true);
+	__cpu_replace_ttbr1(lm_alias(swapper_pg_dir), true);
 }
 
-static inline void cpu_replace_ttbr1(pgd_t *pgdp, pgd_t *idmap)
+static inline void cpu_replace_ttbr1(pgd_t *pgdp)
 {
 	/*
 	 * Only for early TTBR1 replacement before cpucaps are finalized and
 	 * before we've decided whether to use CNP.
 	 */
 	WARN_ON(system_capabilities_finalized());
-	__cpu_replace_ttbr1(pgdp, idmap, false);
+	__cpu_replace_ttbr1(pgdp, false);
 }
 
 /*

arch/arm64/mm/kasan_init.c

@@ -225,7 +225,7 @@ 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), idmap_pg_dir);
+	cpu_replace_ttbr1(lm_alias(tmp_pg_dir));
 
 	clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
 
@@ -261,7 +261,7 @@ 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), idmap_pg_dir);
+	cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
 }
 
 static void __init kasan_init_depth(void)

arch/arm64/mm/mmu.c

@@ -1445,7 +1445,7 @@ void ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr, pte
  * Atomically replaces the active TTBR1_EL1 PGD with a new VA-compatible PGD,
  * avoiding the possibility of conflicting TLB entries being allocated.
  */
-void __cpu_replace_ttbr1(pgd_t *pgdp, pgd_t *idmap, bool cnp)
+void __cpu_replace_ttbr1(pgd_t *pgdp, bool cnp)
 {
 	typedef void (ttbr_replace_func)(phys_addr_t);
 	extern ttbr_replace_func idmap_cpu_replace_ttbr1;
@@ -1460,7 +1460,7 @@ void __cpu_replace_ttbr1(pgd_t *pgdp, pgd_t *idmap, bool cnp)
 
 	replace_phys = (void *)__pa_symbol(idmap_cpu_replace_ttbr1);
 
-	__cpu_install_idmap(idmap);
+	cpu_install_idmap();
 
 	/*
 	 * We really don't want to take *any* exceptions while TTBR1 is