Make CSR test much more robust

1 files changed, 52 insertions, 0 deletions

diff --git a/isa/rv64si/csr.S b/isa/rv64si/csr.S
index 26031bc..846a483 100644
--- a/isa/rv64si/csr.S
+++ b/isa/rv64si/csr.S
@@ -11,6 +11,11 @@
 RVTEST_RV64S
 RVTEST_CODE_BEGIN
 
+  # Set up evec in case we trap.
+  la t0, evec
+  csrw evec, t0
+  csrwi count, 0
+
   csrwi sup0, 3
   TEST_CASE( 2, a0,         3, csrr a0, sup0);
   TEST_CASE( 3, a1,         3, csrrci a1, sup0, 1);
@@ -21,8 +26,55 @@ RVTEST_CODE_BEGIN
   TEST_CASE( 8, a0, 0xbad0000, li a0, 0x000beef; csrrs a0, sup0, a0);
   TEST_CASE( 9, a0, 0xbadbeef, csrr a0, sup0);
 
+  # Make sure writing the cycle counter causes an exception.
+  TEST_CASE(10, a0, 255, li a0, 255; csrrw a0, cycle, x0);
+
+  # Make sure reading status in user mode causes an exception.
+  csrci status, SR_S|SR_PS
+  TEST_CASE(11, a0, 255, li a0, 255; csrr a0, status);
+
+  # Make sure rdcycle is legal in user mode.
+  TEST_CASE(12, x0, 0, rdcycle a0)
+
+  # Exit by doing a syscall.
+  TEST_CASE(13, x0, 1, scall)
+
+  # We should only fall through to this if scall failed.
   TEST_PASSFAIL
 
+evec:
+  # Trapping on tests 10, 11, and 13 is usually good news.
+  # Note that since the test didn't finished, TESTNUM is smaller by 1.
+  li t0, 9
+  beq TESTNUM, t0, privileged
+  li t0, 10
+  beq TESTNUM, t0, privileged
+  li t0, 12
+  beq TESTNUM, t0, syscall
+
+  # Trapping on other tests is bad news.
+  j fail
+
+privileged:
+  # Make sure CAUSE indicates a lack of privilege.
+  csrr t0, cause
+  li t1, CAUSE_PRIVILEGED_INSTRUCTION
+  bne t0, t1, fail
+  # Return to user mode, but skip the trapping instruction.
+  csrr t0, epc
+  addi t0, t0, 4
+  csrw epc, t0
+  sret
+
+syscall:
+  # Make sure CAUSE indicates a syscall.
+  csrr t0, cause
+  li t1, CAUSE_SYSCALL
+  bne t0, t1, fail
+
+  # We're done.
+  j pass
+
 RVTEST_CODE_END
 
   .data