xtensa: save and restore scompare1 SR on kernel entry

Although scompare1 may be saved/restored by xchal_ncp_{load,store}
macros, explicit save/restore of registers manipulated by the kernel
itself is considered more correct.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

1 files changed, 13 insertions, 0 deletions

diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S
index 41ad9cfe9a2a..4c2f2706ad5b 100644
--- a/arch/xtensa/kernel/entry.S
+++ b/arch/xtensa/kernel/entry.S
@@ -372,6 +372,13 @@ common_exception:
         s32i    a2, a1, PT_LBEG
         s32i    a3, a1, PT_LEND
 
+        /* Save SCOMPARE1 */
+
+#if XCHAL_HAVE_S32C1I
+        rsr     a2, scompare1
+        s32i    a2, a1, PT_SCOMPARE1
+#endif
+
         /* Save optional registers. */
 
         save_xtregs_opt a1 a2 a4 a5 a6 a7 PT_XTREGS_OPT
@@ -433,6 +440,12 @@ common_exception_return:
 
         load_xtregs_opt a1 a2 a4 a5 a6 a7 PT_XTREGS_OPT
 
+        /* Restore SCOMPARE1 */
+
+#if XCHAL_HAVE_S32C1I
+        l32i    a2, a1, PT_SCOMPARE1
+        wsr     a2, scompare1
+#endif
         wsr     a3, ps          /* disable interrupts */
 
         _bbci.l a3, PS_UM_BIT, kernel_exception_exit