Merge branches 'fixes' and 'misc' into for-linus

1 files changed, 38 insertions, 3 deletions

diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index ed1c529..5aadc69 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -153,8 +153,7 @@ static int scratchpad_offset(int i)
  */
 static int m4kc_tlbp_war(void)
 {
-	return (current_cpu_data.processor_id & 0xffff00) ==
-	       (PRID_COMP_MIPS | PRID_IMP_4KC);
+	return current_cpu_type() == CPU_4KC;
 }
 
 /* Handle labels (which must be positive integers). */
@@ -2015,6 +2014,26 @@ static void build_r3000_tlb_modify_handler(void)
 }
 #endif /* CONFIG_MIPS_PGD_C0_CONTEXT */
 
+static bool cpu_has_tlbex_tlbp_race(void)
+{
+	/*
+	 * When a Hardware Table Walker is running it can replace TLB entries
+	 * at any time, leading to a race between it & the CPU.
+	 */
+	if (cpu_has_htw)
+		return true;
+
+	/*
+	 * If the CPU shares FTLB RAM with its siblings then our entry may be
+	 * replaced at any time by a sibling performing a write to the FTLB.
+	 */
+	if (cpu_has_shared_ftlb_ram)
+		return true;
+
+	/* In all other cases there ought to be no race condition to handle */
+	return false;
+}
+
 /*
  * R4000 style TLB load/store/modify handlers.
  */
@@ -2051,7 +2070,7 @@ build_r4000_tlbchange_handler_head(u32 **p, struct uasm_label **l,
 	iPTE_LW(p, wr.r1, wr.r2); /* get even pte */
 	if (!m4kc_tlbp_war()) {
 		build_tlb_probe_entry(p);
-		if (cpu_has_htw) {
+		if (cpu_has_tlbex_tlbp_race()) {
 			/* race condition happens, leaving */
 			uasm_i_ehb(p);
 			uasm_i_mfc0(p, wr.r3, C0_INDEX);
@@ -2125,6 +2144,14 @@ static void build_r4000_tlb_load_handler(void)
 		}
 		uasm_i_nop(&p);
 
+		/*
+		 * Warn if something may race with us & replace the TLB entry
+		 * before we read it here. Everything with such races should
+		 * also have dedicated RiXi exception handlers, so this
+		 * shouldn't be hit.
+		 */
+		WARN(cpu_has_tlbex_tlbp_race(), "Unhandled race in RiXi path");
+
 		uasm_i_tlbr(&p);
 
 		switch (current_cpu_type()) {
@@ -2192,6 +2219,14 @@ static void build_r4000_tlb_load_handler(void)
 		}
 		uasm_i_nop(&p);
 
+		/*
+		 * Warn if something may race with us & replace the TLB entry
+		 * before we read it here. Everything with such races should
+		 * also have dedicated RiXi exception handlers, so this
+		 * shouldn't be hit.
+		 */
+		WARN(cpu_has_tlbex_tlbp_race(), "Unhandled race in RiXi path");
+
 		uasm_i_tlbr(&p);
 
 		switch (current_cpu_type()) {