trap_handler_gfx12: Do not override STATE_PRIV.BARRIER_COMPLETE

The value of STATE_PRIV is captured by the 1st level trap handler, and
passed on to the second level trap handler.  The value is to be restored
before exit.  However it is possible for the value of
STATE_PRIV.BARRIER_COMPLETE to change while the wave is in the trap
handler (all the other waves in the workgroup has signaled the
work-gropu barrier), and in this case restoring STATE_PRIV in full would
result in STATE_PRIV.BARRIER_COMPLETE to be cleared.

Restore every bits of STATE_PRIV except for BARRIER_COMPLETE before
return to prevent this race.

Change-Id: I76c875bced7d23c58670b28f257d22c933f99fc5
Signed-off-by: Chris Freehill <cfreehil@amd.com>

runtime/hsa-runtime/core/runtime/trap_handler/trap_handler_gfx12.s

@@ -63,6 +63,7 @@
 .set SQ_WAVE_PC_HI_TRAP_ID_SIZE                , 4
 .set SQ_WAVE_STATE_PRIV_HALT_BFE               , (SQ_WAVE_STATE_PRIV_HALT_SHIFT | (1 << 16))
 .set SQ_WAVE_STATE_PRIV_HALT_SHIFT             , 14
+.set SQ_WAVE_STATE_PRIV_BARRIER_COMPLETE_SHIFT , 2
 .set TRAP_ID_ABORT                             , 2
 .set TRAP_ID_DEBUGTRAP                         , 3
 .set TTMP6_SAVED_STATUS_HALT_MASK              , (1 << TTMP6_SAVED_STATUS_HALT_SHIFT)
@@ -208,7 +209,9 @@ trap_entry:
   // Restore SQ_WAVE_STATUS.
   s_and_b64            exec, exec, exec // Restore STATUS.EXECZ, not writable by s_setreg_b32
   s_and_b64            vcc, vcc, vcc    // Restore STATUS.VCCZ, not writable by s_setreg_b32
-  s_setreg_b32         hwreg(HW_REG_STATE_PRIV), ttmp12
+  s_setreg_b32         hwreg(HW_REG_STATE_PRIV, 0, SQ_WAVE_STATE_PRIV_BARRIER_COMPLETE_SHIFT), ttmp12
+  s_lshr_b32           ttmp12, ttmp12, (SQ_WAVE_STATE_PRIV_BARRIER_COMPLETE_SHIFT + 1)
+  s_setreg_b32         hwreg(HW_REG_STATE_PRIV, SQ_WAVE_STATE_PRIV_BARRIER_COMPLETE_SHIFT + 1, 32 - SQ_WAVE_STATE_PRIV_BARRIER_COMPLETE_SHIFT - 1), ttmp12
 
   // Return to original (possibly modified) PC.
   s_rfe_b64            [ttmp0, ttmp1]