[PATCH V3] MIPS: flush TLB handlers directly after writing them

[Jonas Gorski <jogo@openwrt.org>]

When having enabled MIPS_PGD_C0_CONTEXT, trap_init() might call the
generated tlbmiss_handler_setup_pgd before it was committed to memory,
causing boot failures:

  trap_init()
   |- per_cpu_trap_init()
   |   |- TLBMISS_HANDLER_SETUP()
   |       |- tlbmiss_handler_setup_pgd()
   |- flush_tlb_handlers()

To avoid this, move flush_tlb_handlers() into build_tlb_refill_handler()
right after they were generated. We can do this as the cache handling is
initialized just before creating the tlb handlers.

This issue was introduced in 3d8bfdd0307223de678962f1c1907a7cec549136
("MIPS: Use C0_KScratch (if present) to hold PGD pointer.").

Signed-off-by: Jonas Gorski <jogo@openwrt.org>
---
@Ralf, this is a direct replacement for V2.

V2 -> V3:
 * Move flush_tlb_handlers() call into build_tlb_refill_handler() as
   suggested by Jayachandran C.
 * Make it static as now doesn't need to be called from external anymore.
 * Move it on top of build_tlb_refill_handler() to avoid having to add a
   prototype for it.

V1 -> V2:
 * Move flush_tlb_handlers into per_cpu_trap_init() to also fix it for
   !boot_cpu.

 arch/mips/kernel/traps.c |    2 --
 arch/mips/mm/tlbex.c     |   30 ++++++++++++++++--------------
 2 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 142d2be..f44366d 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -1668,7 +1668,6 @@ void *set_vi_handler(int n, vi_handler_t addr)
 }
 
 extern void tlb_init(void);
-extern void flush_tlb_handlers(void);
 
 /*
  * Timer interrupt
@@ -1997,7 +1996,6 @@ void __init trap_init(void)
 		set_handler(0x080, &except_vec3_generic, 0x80);
 
 	local_flush_icache_range(ebase, ebase + 0x400);
-	flush_tlb_handlers();
 
 	sort_extable(__start___dbe_table, __stop___dbe_table);
 
diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index f1eabe7..02b1b22 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -2192,6 +2192,20 @@ static void __cpuinit build_r4000_tlb_modify_handler(void)
 	dump_handler("r4000_tlb_modify", handle_tlbm, ARRAY_SIZE(handle_tlbm));
 }
 
+static void __cpuinit flush_tlb_handlers(void)
+{
+	local_flush_icache_range((unsigned long)handle_tlbl,
+			   (unsigned long)handle_tlbl + sizeof(handle_tlbl));
+	local_flush_icache_range((unsigned long)handle_tlbs,
+			   (unsigned long)handle_tlbs + sizeof(handle_tlbs));
+	local_flush_icache_range((unsigned long)handle_tlbm,
+			   (unsigned long)handle_tlbm + sizeof(handle_tlbm));
+#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
+	local_flush_icache_range((unsigned long)tlbmiss_handler_setup_pgd_array,
+			   (unsigned long)tlbmiss_handler_setup_pgd_array + sizeof(handle_tlbm));
+#endif
+}
+
 void __cpuinit build_tlb_refill_handler(void)
 {
 	/*
@@ -2224,6 +2238,7 @@ void __cpuinit build_tlb_refill_handler(void)
 			build_r3000_tlb_load_handler();
 			build_r3000_tlb_store_handler();
 			build_r3000_tlb_modify_handler();
+			flush_tlb_handlers();
 			run_once++;
 		}
 #else
@@ -2251,23 +2266,10 @@ void __cpuinit build_tlb_refill_handler(void)
 			build_r4000_tlb_modify_handler();
 			if (!cpu_has_local_ebase)
 				build_r4000_tlb_refill_handler();
+			flush_tlb_handlers();
 			run_once++;
 		}
 		if (cpu_has_local_ebase)
 			build_r4000_tlb_refill_handler();
 	}
 }
-
-void __cpuinit flush_tlb_handlers(void)
-{
-	local_flush_icache_range((unsigned long)handle_tlbl,
-			   (unsigned long)handle_tlbl + sizeof(handle_tlbl));
-	local_flush_icache_range((unsigned long)handle_tlbs,
-			   (unsigned long)handle_tlbs + sizeof(handle_tlbs));
-	local_flush_icache_range((unsigned long)handle_tlbm,
-			   (unsigned long)handle_tlbm + sizeof(handle_tlbm));
-#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
-	local_flush_icache_range((unsigned long)tlbmiss_handler_setup_pgd_array,
-			   (unsigned long)tlbmiss_handler_setup_pgd_array + sizeof(handle_tlbm));
-#endif
-}
-- 
1.7.10.4