1 files changed, 45 insertions, 2 deletions

diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index bc829fc2421d..6b7cc20efd92 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -311,6 +311,7 @@ static struct uasm_label labels[128];
 static struct uasm_reloc relocs[128];
 
 static int check_for_high_segbits;
+static bool fill_includes_sw_bits;
 
 static unsigned int kscratch_used_mask;
 
@@ -630,8 +631,14 @@ 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 (cpu_has_rixi) {
-		UASM_i_ROTR(p, reg, reg, ilog2(_PAGE_GLOBAL));
+	if (cpu_has_rixi && _PAGE_NO_EXEC) {
+		if (fill_includes_sw_bits) {
+			UASM_i_ROTR(p, reg, reg, ilog2(_PAGE_GLOBAL));
+		} else {
+			UASM_i_SRL(p, reg, reg, ilog2(_PAGE_NO_EXEC));
+			UASM_i_ROTR(p, reg, reg,
+				    ilog2(_PAGE_GLOBAL) - ilog2(_PAGE_NO_EXEC));
+		}
 	} else {
 #ifdef CONFIG_PHYS_ADDR_T_64BIT
 		uasm_i_dsrl_safe(p, reg, reg, ilog2(_PAGE_GLOBAL));
@@ -2338,6 +2345,41 @@ static void config_xpa_params(void)
 #endif
 }
 
+static void check_pabits(void)
+{
+	unsigned long entry;
+	unsigned pabits, fillbits;
+
+	if (!cpu_has_rixi || !_PAGE_NO_EXEC) {
+		/*
+		 * We'll only be making use of the fact that we can rotate bits
+		 * into the fill if the CPU supports RIXI, so don't bother
+		 * probing this for CPUs which don't.
+		 */
+		return;
+	}
+
+	write_c0_entrylo0(~0ul);
+	back_to_back_c0_hazard();
+	entry = read_c0_entrylo0();
+
+	/* clear all non-PFN bits */
+	entry &= ~((1 << MIPS_ENTRYLO_PFN_SHIFT) - 1);
+	entry &= ~(MIPS_ENTRYLO_RI | MIPS_ENTRYLO_XI);
+
+	/* find a lower bound on PABITS, and upper bound on fill bits */
+	pabits = fls_long(entry) + 6;
+	fillbits = max_t(int, (int)BITS_PER_LONG - pabits, 0);
+
+	/* minus the RI & XI bits */
+	fillbits -= min_t(unsigned, fillbits, 2);
+
+	if (fillbits >= ilog2(_PAGE_NO_EXEC))
+		fill_includes_sw_bits = true;
+
+	pr_debug("Entry* registers contain %u fill bits\n", fillbits);
+}
+
 void build_tlb_refill_handler(void)
 {
 	/*
@@ -2348,6 +2390,7 @@ void build_tlb_refill_handler(void)
 	static int run_once = 0;
 
 	output_pgtable_bits_defines();
+	check_pabits();
 
 #ifdef CONFIG_64BIT
 	check_for_high_segbits = current_cpu_data.vmbits > (PGDIR_SHIFT + PGD_ORDER + PAGE_SHIFT - 3);