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-rw-r--r--arch/mips/mm/tlbex.c38
1 files changed, 37 insertions, 1 deletions
diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index ed1c529..e649920 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -2015,6 +2015,26 @@ 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 +2071,7 @@ 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 +2145,14 @@ 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 +2220,14 @@ 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()) {
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