[PATCH 3.19 081/175] MIPS: asm: pgtable: Add c0 hazards on HTW start/stop sequences

[Greg Kroah-Hartman]

3.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Markos Chandras <markos.chandras@xxxxxxxxxx>

commit 461d1597ffad7a826f8aaa63ab0727c37b632e34 upstream.

When we use htw_{start,stop}() outside of htw_reset(), we need
to ensure that c0 changes have been propagated properly before
we attempt to continue with subsequence memory operations.

Signed-off-by: Markos Chandras <markos.chandras@xxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Patchwork: https://patchwork.linux-mips.org/patch/9114/
Signed-off-by: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/mips/include/asm/pgtable.h |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -99,16 +99,20 @@ extern void paging_init(void);
 
 #define htw_stop()							\
 do {									\
-	if (cpu_has_htw)						\
+	if (cpu_has_htw) {						\
 		write_c0_pwctl(read_c0_pwctl() &			\
 			       ~(1 << MIPS_PWCTL_PWEN_SHIFT));		\
+		back_to_back_c0_hazard();				\
+	}								\
 } while(0)
 
 #define htw_start()							\
 do {									\
-	if (cpu_has_htw)						\
+	if (cpu_has_htw) {						\
 		write_c0_pwctl(read_c0_pwctl() |			\
 			       (1 << MIPS_PWCTL_PWEN_SHIFT));		\
+		back_to_back_c0_hazard();				\
+	}								\
 } while(0)
 
 
@@ -116,9 +120,7 @@ do {									\
 do {									\
 	if (cpu_has_htw) {						\
 		htw_stop();						\
-		back_to_back_c0_hazard();				\
 		htw_start();						\
-		back_to_back_c0_hazard();				\
 	}								\
 } while(0)
 


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