xtensa: check thread flags atomically on return from user exception

Check pending signals and rescheduling thread flags with interrupts
disabled, and don't enable them if no flags are set. Call
trace_hardirqs_on after thread flags handling, so that rescheduling is
done and hardirqs tracking flag is updated in the correct task context.

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

1 files changed, 21 insertions, 18 deletions

diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S
index 9298742f0fd0..03709ef2f3ce 100644
--- a/arch/xtensa/kernel/entry.S
+++ b/arch/xtensa/kernel/entry.S
@@ -423,29 +423,14 @@ common_exception:
         .global common_exception_return
 common_exception_return:
 
-#ifdef CONFIG_TRACE_IRQFLAGS
-        l32i    a4, a1, PT_DEPC
-        /* Double exception means we came here with an exception
-         * while PS.EXCM was set, i.e. interrupts disabled.
-         */
-        bgeui   a4, VALID_DOUBLE_EXCEPTION_ADDRESS, 1f
-        l32i    a4, a1, PT_EXCCAUSE
-        bnei    a4, EXCCAUSE_LEVEL1_INTERRUPT, 1f
-        /* We came here with an interrupt means interrupts were enabled
-         * and we'll reenable them on return.
-         */
-        movi    a4, trace_hardirqs_on
-        callx4  a4
 1:
-#endif
+        rsil    a2, LOCKLEVEL
 
         /* Jump if we are returning from kernel exceptions. */
 
-1:      l32i    a3, a1, PT_PS
+        l32i    a3, a1, PT_PS
         _bbci.l a3, PS_UM_BIT, 4f
 
-        rsil    a2, 0
-
         /* Specific to a user exception exit:
          * We need to check some flags for signal handling and rescheduling,
          * and have to restore WB and WS, extra states, and all registers
@@ -465,6 +450,7 @@ common_exception_return:
 
         /* Call do_signal() */
 
+        rsil    a2, 0
         movi    a4, do_notify_resume    # int do_notify_resume(struct pt_regs*)
         mov     a6, a1
         callx4  a4
@@ -472,6 +458,7 @@ common_exception_return:
 
 3:      /* Reschedule */
 
+        rsil    a2, 0
         movi    a4, schedule    # void schedule (void)
         callx4  a4
         j       1b
@@ -483,7 +470,23 @@ common_exception_return:
         movi    a4, check_tlb_sanity
         callx4  a4
 #endif
-4:      /* Restore optional registers. */
+4:
+#ifdef CONFIG_TRACE_IRQFLAGS
+        l32i    a4, a1, PT_DEPC
+        /* Double exception means we came here with an exception
+         * while PS.EXCM was set, i.e. interrupts disabled.
+         */
+        bgeui   a4, VALID_DOUBLE_EXCEPTION_ADDRESS, 1f
+        l32i    a4, a1, PT_EXCCAUSE
+        bnei    a4, EXCCAUSE_LEVEL1_INTERRUPT, 1f
+        /* We came here with an interrupt means interrupts were enabled
+         * and we'll reenable them on return.
+         */
+        movi    a4, trace_hardirqs_on
+        callx4  a4
+1:
+#endif
+        /* Restore optional registers. */
 
         load_xtregs_opt a1 a2 a4 a5 a6 a7 PT_XTREGS_OPT