MIPS: mm: Simplify build_update_entries

We can simplify build_update_entries by unifying the code for the 36 bit
physical addressing with MIPS32 case with the general case, by using
pte_off_ variables in all cases & handling the trivial
_PAGE_GLOBAL_SHIFT == 0 case in build_convert_pte_to_entrylo. This
leaves XPA as the only special case.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13123/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/mm/tlbex.c

@@ -631,6 +631,11 @@ static void build_tlb_write_entry(u32 **p, struct uasm_label **l,
 static __maybe_unused void build_convert_pte_to_entrylo(u32 **p,
 							unsigned int reg)
 {
+	if (_PAGE_GLOBAL_SHIFT == 0) {
+		/* pte_t is already in EntryLo format */
+		return;
+	}
+
 	if (cpu_has_rixi && _PAGE_NO_EXEC) {
 		if (fill_includes_sw_bits) {
 			UASM_i_ROTR(p, reg, reg, ilog2(_PAGE_GLOBAL));
@@ -1011,10 +1016,16 @@ static void build_get_ptep(u32 **p, unsigned int tmp, unsigned int ptr)
 
 static void build_update_entries(u32 **p, unsigned int tmp, unsigned int ptep)
 {
-	if (config_enabled(CONFIG_XPA)) {
-		int pte_off_even = sizeof(pte_t) / 2;
-		int pte_off_odd = pte_off_even + sizeof(pte_t);
+	int pte_off_even = 0;
+	int pte_off_odd = sizeof(pte_t);
 
+#if defined(CONFIG_CPU_MIPS32) && defined(CONFIG_PHYS_ADDR_T_64BIT)
+	/* The low 32 bits of EntryLo is stored in pte_high */
+	pte_off_even += offsetof(pte_t, pte_high);
+	pte_off_odd += offsetof(pte_t, pte_high);
+#endif
+
+	if (config_enabled(CONFIG_XPA)) {
 		uasm_i_lw(p, tmp, pte_off_even, ptep); /* even pte */
 		UASM_i_ROTR(p, tmp, tmp, ilog2(_PAGE_GLOBAL));
 		UASM_i_MTC0(p, tmp, C0_ENTRYLO0);
@@ -1033,24 +1044,8 @@ static void build_update_entries(u32 **p, unsigned int tmp, unsigned int ptep)
 		return;
 	}
 
-	/*
-	 * 64bit address support (36bit on a 32bit CPU) in a 32bit
-	 * Kernel is a special case. Only a few CPUs use it.
-	 */
-	if (config_enabled(CONFIG_PHYS_ADDR_T_64BIT) && !cpu_has_64bits) {
-		int pte_off_even = sizeof(pte_t) / 2;
-		int pte_off_odd = pte_off_even + sizeof(pte_t);
-
-		uasm_i_lw(p, tmp, pte_off_even, ptep); /* even pte */
-		UASM_i_MTC0(p, tmp, C0_ENTRYLO0);
-
-		uasm_i_lw(p, ptep, pte_off_odd, ptep); /* odd pte */
-		UASM_i_MTC0(p, ptep, C0_ENTRYLO1);
-		return;
-	}
-
-	UASM_i_LW(p, tmp, 0, ptep); /* get even pte */
-	UASM_i_LW(p, ptep, sizeof(pte_t), ptep); /* get odd pte */
+	UASM_i_LW(p, tmp, pte_off_even, ptep); /* get even pte */
+	UASM_i_LW(p, ptep, pte_off_odd, ptep); /* get odd pte */
 	if (r45k_bvahwbug())
 		build_tlb_probe_entry(p);
 	build_convert_pte_to_entrylo(p, tmp);