From ec297672b0c9d58d1ee6c2ac976ccf28863bd3c2 Mon Sep 17 00:00:00 2001
From: Andrew Waterman <aswaterman@gmail.com>
Date: Fri, 2 Jan 2015 17:29:05 -0800
Subject: [PATCH] On misaligned fetch, set EPC to target, not branch itself

---
 riscv/decode.h     | 6 +-----
 riscv/insns/jal.h  | 3 ++-
 riscv/insns/jalr.h | 6 +++---
 riscv/mmu.h        | 4 +++-
 4 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/riscv/decode.h b/riscv/decode.h
index b325c59..6d1ffbe 100644
--- a/riscv/decode.h
+++ b/riscv/decode.h
@@ -155,11 +155,7 @@ private:
    ((x) & 0x3f) < 0x3f ? 6 : \
    8)
 
-#define set_pc(x) \
-  do { if ((x) & 3 /* For now... */) \
-         throw trap_instruction_address_misaligned(x); \
-       npc = sext_xprlen(x); \
-     } while(0)
+#define set_pc(x) (npc = sext_xprlen(x))
 
 #define validate_csr(which, write) ({ \
   unsigned my_priv = (STATE.sr & SR_S) ? 1 : 0; \
diff --git a/riscv/insns/jal.h b/riscv/insns/jal.h
index 2694dee..cd59964 100644
--- a/riscv/insns/jal.h
+++ b/riscv/insns/jal.h
@@ -1,2 +1,3 @@
-WRITE_RD(npc);
+reg_t tmp = npc;
 set_pc(JUMP_TARGET);
+WRITE_RD(tmp);
diff --git a/riscv/insns/jalr.h b/riscv/insns/jalr.h
index 3924aa4..386e8db 100644
--- a/riscv/insns/jalr.h
+++ b/riscv/insns/jalr.h
@@ -1,3 +1,3 @@
-reg_t temp = RS1;
-WRITE_RD(npc);
-set_pc((temp + insn.i_imm()) & ~1);
+reg_t tmp = npc;
+set_pc((RS1 + insn.i_imm()) & ~reg_t(1));
+WRITE_RD(tmp);
diff --git a/riscv/mmu.h b/riscv/mmu.h
index 08d41be..d24ed18 100644
--- a/riscv/mmu.h
+++ b/riscv/mmu.h
@@ -167,7 +167,9 @@ private:
     void* data = tlb_data[idx] + addr;
 
     if (unlikely(addr & (bytes-1)))
-      store ? throw trap_store_address_misaligned(addr) : throw trap_load_address_misaligned(addr);
+      store ? throw trap_store_address_misaligned(addr) :
+      fetch ? throw trap_instruction_address_misaligned(addr) :
+      throw trap_load_address_misaligned(addr);
 
     if (likely(tag == expected_tag))
       return data;
-- 
2.30.2