From 752a7e8060714fff531493c8d4d8a710d547a8bf Mon Sep 17 00:00:00 2001
From: Andrew Waterman <waterman@eecs.berkeley.edu>
Date: Tue, 8 Jul 2014 13:25:04 -0700
Subject: [PATCH] Disallow access to FCSR when FP is disabled

---
 riscv/decode.h     | 35 ++++++++++++++++++-----------------
 riscv/processor.cc |  6 ++++++
 2 files changed, 24 insertions(+), 17 deletions(-)

diff --git a/riscv/decode.h b/riscv/decode.h
index ce57c77..d647b2c 100644
--- a/riscv/decode.h
+++ b/riscv/decode.h
@@ -94,30 +94,31 @@ private:
 
 // helpful macros, etc
 #define MMU (*p->get_mmu())
-#define RS1 p->get_state()->XPR[insn.rs1()]
-#define RS2 p->get_state()->XPR[insn.rs2()]
-#define WRITE_RD(value) p->get_state()->XPR.write(insn.rd(), value)
+#define STATE (*p->get_state())
+#define RS1 STATE.XPR[insn.rs1()]
+#define RS2 STATE.XPR[insn.rs2()]
+#define WRITE_RD(value) STATE.XPR.write(insn.rd(), value)
 
 #ifdef RISCV_ENABLE_COMMITLOG
   #undef WRITE_RD 
   #define WRITE_RD(value) ({ \
         reg_t wdata = value; /* value is a func with side-effects */ \
-        p->get_state()->log_reg_write = (commit_log_reg_t){insn.rd() << 1, wdata}; \
-        p->get_state()->XPR.write(insn.rd(), wdata); \
+        STATE.log_reg_write = (commit_log_reg_t){insn.rd() << 1, wdata}; \
+        STATE.XPR.write(insn.rd(), wdata); \
       })
 #endif
 
-#define FRS1 p->get_state()->FPR[insn.rs1()]
-#define FRS2 p->get_state()->FPR[insn.rs2()]
-#define FRS3 p->get_state()->FPR[insn.rs3()]
-#define WRITE_FRD(value) p->get_state()->FPR.write(insn.rd(), value)
+#define FRS1 STATE.FPR[insn.rs1()]
+#define FRS2 STATE.FPR[insn.rs2()]
+#define FRS3 STATE.FPR[insn.rs3()]
+#define WRITE_FRD(value) STATE.FPR.write(insn.rd(), value)
  
 #ifdef RISCV_ENABLE_COMMITLOG
   #undef WRITE_FRD 
   #define WRITE_FRD(value) ({ \
         freg_t wdata = value; /* value is a func with side-effects */ \
-        p->get_state()->log_reg_write = (commit_log_reg_t){(insn.rd() << 1) | 1, wdata}; \
-        p->get_state()->FPR.write(insn.rd(), wdata); \
+        STATE.log_reg_write = (commit_log_reg_t){(insn.rd() << 1) | 1, wdata}; \
+        STATE.FPR.write(insn.rd(), wdata); \
       })
 #endif
  
@@ -127,24 +128,24 @@ private:
 #define BRANCH_TARGET (pc + insn.sb_imm())
 #define JUMP_TARGET (pc + insn.uj_imm())
 #define RM ({ int rm = insn.rm(); \
-              if(rm == 7) rm = p->get_state()->frm; \
+              if(rm == 7) rm = STATE.frm; \
               if(rm > 4) throw trap_illegal_instruction(); \
               rm; })
 
 #define xpr64 (xprlen == 64)
 
-#define require_supervisor if(unlikely(!(p->get_state()->sr & SR_S))) throw trap_privileged_instruction()
+#define require_supervisor if(unlikely(!(STATE.sr & SR_S))) throw trap_privileged_instruction()
 #define require_xpr64 if(unlikely(!xpr64)) throw trap_illegal_instruction()
 #define require_xpr32 if(unlikely(xpr64)) throw trap_illegal_instruction()
 #ifndef RISCV_ENABLE_FPU
 # define require_fp throw trap_illegal_instruction()
 #else
-# define require_fp if(unlikely(!(p->get_state()->sr & SR_EF))) throw trap_fp_disabled()
+# define require_fp if(unlikely(!(STATE.sr & SR_EF))) throw trap_fp_disabled()
 #endif
-#define require_accelerator if(unlikely(!(p->get_state()->sr & SR_EA))) throw trap_accelerator_disabled()
+#define require_accelerator if(unlikely(!(STATE.sr & SR_EA))) throw trap_accelerator_disabled()
 
 #define cmp_trunc(reg) (reg_t(reg) << (64-xprlen))
-#define set_fp_exceptions ({ p->get_state()->fflags |= softfloat_exceptionFlags; \
+#define set_fp_exceptions ({ STATE.fflags |= softfloat_exceptionFlags; \
                              softfloat_exceptionFlags = 0; })
 
 #define sext32(x) ((sreg_t)(int32_t)(x))
@@ -165,7 +166,7 @@ private:
      } while(0)
 
 #define validate_csr(which, write) ({ \
-  unsigned my_priv = (p->get_state()->sr & SR_S) ? 1 : 0; \
+  unsigned my_priv = (STATE.sr & SR_S) ? 1 : 0; \
   unsigned read_priv = ((which) >> 10) & 3; \
   unsigned write_priv = (((which) >> 8) & 3); \
   if (read_priv == 3) read_priv = write_priv, write_priv = -1; \
diff --git a/riscv/processor.cc b/riscv/processor.cc
index 284f281..8ba87ed 100644
--- a/riscv/processor.cc
+++ b/riscv/processor.cc
@@ -17,6 +17,9 @@
 #include <stdexcept>
 #include <algorithm>
 
+#undef STATE
+#define STATE state
+
 processor_t::processor_t(sim_t* _sim, mmu_t* _mmu, uint32_t _id)
   : sim(_sim), mmu(_mmu), ext(NULL), disassembler(new disassembler_t),
     id(_id), run(false), debug(false)
@@ -294,10 +297,13 @@ reg_t processor_t::get_pcr(int which)
   switch (which)
   {
     case CSR_FFLAGS:
+      require_fp;
       return state.fflags;
     case CSR_FRM:
+      require_fp;
       return state.frm;
     case CSR_FCSR:
+      require_fp;
       return (state.fflags << FSR_AEXC_SHIFT) | (state.frm << FSR_RD_SHIFT);
     case CSR_STATUS:
       return state.sr;
-- 
2.30.2