From f7f2623753d4bbe776087d4e6f5190a0a92305c5 Mon Sep 17 00:00:00 2001
From: Tim Newsome <tim@sifive.com>
Date: Thu, 28 Apr 2016 13:15:46 -0700
Subject: [PATCH] Fix race using fence.

---
 debug_rom/debug_rom.S |  6 +-----
 debug_rom/debug_rom.h | 31 +++++++++++++++----------------
 2 files changed, 16 insertions(+), 21 deletions(-)

diff --git a/debug_rom/debug_rom.S b/debug_rom/debug_rom.S
index 9825d48..a3339b4 100755
--- a/debug_rom/debug_rom.S
+++ b/debug_rom/debug_rom.S
@@ -32,11 +32,7 @@ resume:
 clear_debint:
         csrr    s1, CSR_MHARTID
         sw      s1, CLEARDEBINT(zero)
-        # TODO: race: what if the debugger sets debug int at this point?
-clear_debint_loop:
-        csrr    s1, DCSR
-        andi    s1, s1, (1<<DCSR_DEBUGINT_OFFSET)
-        bnez    s1, clear_debint_loop
+        fence
 
         # Restore s1.
         csrr    s1, CSR_MISA
diff --git a/debug_rom/debug_rom.h b/debug_rom/debug_rom.h
index 6fef948..b096c80 100644
--- a/debug_rom/debug_rom.h
+++ b/debug_rom/debug_rom.h
@@ -1,18 +1,17 @@
 static const unsigned char debug_rom_raw[] = {
-  0x6f, 0x00, 0x40, 0x05, 0xf3, 0x24, 0x50, 0xf1, 0x23, 0x2c, 0x90, 0xee,
-  0xf3, 0x24, 0x00, 0x79, 0x93, 0xf4, 0x04, 0x40, 0xe3, 0x9c, 0x04, 0xfe,
-  0xf3, 0x24, 0x00, 0xf1, 0x63, 0xc6, 0x04, 0x00, 0x83, 0x24, 0xc0, 0xc3,
-  0x6f, 0x00, 0x80, 0x01, 0x93, 0x94, 0x14, 0x00, 0x63, 0xc6, 0x04, 0x00,
-  0x83, 0x34, 0x80, 0xc3, 0x6f, 0x00, 0x80, 0x00, 0x13, 0x00, 0x00, 0x00,
-  0x73, 0x24, 0x00, 0x79, 0x13, 0x74, 0x84, 0x00, 0x63, 0x04, 0x04, 0x00,
-  0x6f, 0x00, 0x40, 0x05, 0x73, 0x24, 0x20, 0x79, 0x73, 0x00, 0x00, 0x10,
-  0x73, 0x10, 0x24, 0x79, 0x73, 0x24, 0x00, 0x79, 0x13, 0x74, 0x74, 0x00,
-  0x13, 0x04, 0xd4, 0xff, 0x63, 0x16, 0x04, 0x02, 0x73, 0x24, 0x00, 0xf1,
-  0x63, 0x46, 0x04, 0x00, 0x23, 0x2e, 0x90, 0xc2, 0x67, 0x00, 0x00, 0xc0,
-  0x13, 0x14, 0x14, 0x00, 0x63, 0x46, 0x04, 0x00, 0x23, 0x3c, 0x90, 0xc2,
-  0x67, 0x00, 0x00, 0xc0, 0x13, 0x00, 0x00, 0x00, 0x67, 0x00, 0x00, 0xc0,
-  0x73, 0x24, 0x50, 0xf1, 0x23, 0x20, 0x80, 0xf0, 0x73, 0x60, 0x04, 0x79,
-  0x73, 0x24, 0x00, 0x79, 0x13, 0x74, 0x04, 0x40, 0xe3, 0x0c, 0x04, 0xfe,
-  0x6f, 0xf0, 0x1f, 0xfc
+  0x6f, 0x00, 0xc0, 0x04, 0xf3, 0x24, 0x50, 0xf1, 0x23, 0x2c, 0x90, 0xee,
+  0x0f, 0x00, 0xf0, 0x0f, 0xf3, 0x24, 0x00, 0xf1, 0x63, 0xc6, 0x04, 0x00,
+  0x83, 0x24, 0xc0, 0xc3, 0x6f, 0x00, 0x80, 0x01, 0x93, 0x94, 0x14, 0x00,
+  0x63, 0xc6, 0x04, 0x00, 0x83, 0x34, 0x80, 0xc3, 0x6f, 0x00, 0x80, 0x00,
+  0x13, 0x00, 0x00, 0x00, 0x73, 0x24, 0x00, 0x79, 0x13, 0x74, 0x84, 0x00,
+  0x63, 0x04, 0x04, 0x00, 0x6f, 0x00, 0x40, 0x05, 0x73, 0x24, 0x20, 0x79,
+  0x73, 0x00, 0x00, 0x10, 0x73, 0x10, 0x24, 0x79, 0x73, 0x24, 0x00, 0x79,
+  0x13, 0x74, 0x74, 0x00, 0x13, 0x04, 0xd4, 0xff, 0x63, 0x16, 0x04, 0x02,
+  0x73, 0x24, 0x00, 0xf1, 0x63, 0x46, 0x04, 0x00, 0x23, 0x2e, 0x90, 0xc2,
+  0x67, 0x00, 0x00, 0xc0, 0x13, 0x14, 0x14, 0x00, 0x63, 0x46, 0x04, 0x00,
+  0x23, 0x3c, 0x90, 0xc2, 0x67, 0x00, 0x00, 0xc0, 0x13, 0x00, 0x00, 0x00,
+  0x67, 0x00, 0x00, 0xc0, 0x73, 0x24, 0x50, 0xf1, 0x23, 0x20, 0x80, 0xf0,
+  0x73, 0x60, 0x04, 0x79, 0x73, 0x24, 0x00, 0x79, 0x13, 0x74, 0x04, 0x40,
+  0xe3, 0x0c, 0x04, 0xfe, 0x6f, 0xf0, 0x1f, 0xfc
 };
-static const unsigned int debug_rom_raw_len = 172;
+static const unsigned int debug_rom_raw_len = 164;
-- 
2.30.2