[PATCH v8 12/17] target/riscv: AMO operations always raise store/AMO fault

[Deepak Gupta <debug@rivosinc.com>]

This patch adds one more word for tcg compile which can be obtained during
unwind time to determine fault type for original operation (example AMO).
Depending on that, fault can be promoted to store/AMO fault.

Signed-off-by: Deepak Gupta <debug@rivosinc.com>
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/riscv/cpu.h         |  9 ++++++++-
 target/riscv/cpu_helper.c  | 20 ++++++++++++++++++++
 target/riscv/tcg/tcg-cpu.c |  1 +
 target/riscv/translate.c   |  2 +-
 4 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index dcc3bc9d93..3143141863 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -46,8 +46,13 @@ typedef struct CPUArchState CPURISCVState;
 /*
  * RISC-V-specific extra insn start words:
  * 1: Original instruction opcode
+ * 2: more information about instruction
  */
-#define TARGET_INSN_START_EXTRA_WORDS 1
+#define TARGET_INSN_START_EXTRA_WORDS 2
+/*
+ * b0: Whether a instruction always raise a store AMO or not.
+ */
+#define RISCV_UW2_ALWAYS_STORE_AMO 1
 
 #define RV(x) ((target_ulong)1 << (x - 'A'))
 
@@ -226,6 +231,8 @@ struct CPUArchState {
     bool      elp;
     /* shadow stack register for zicfiss extension */
     target_ulong ssp;
+    /* env place holder for extra word 2 during unwind */
+    target_ulong excp_uw2;
     /* sw check code for sw check exception */
     target_ulong sw_check_code;
 #ifdef CONFIG_USER_ONLY
diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index 95ef7b0bd1..0f32bede39 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -1740,6 +1740,22 @@ static target_ulong riscv_transformed_insn(CPURISCVState *env,
     return xinsn;
 }
 
+static target_ulong promote_load_fault(target_ulong orig_cause)
+{
+    switch (orig_cause) {
+    case RISCV_EXCP_LOAD_GUEST_ACCESS_FAULT:
+        return RISCV_EXCP_STORE_GUEST_AMO_ACCESS_FAULT;
+
+    case RISCV_EXCP_LOAD_ACCESS_FAULT:
+        return RISCV_EXCP_STORE_AMO_ACCESS_FAULT;
+
+    case RISCV_EXCP_LOAD_PAGE_FAULT:
+        return RISCV_EXCP_STORE_PAGE_FAULT;
+    }
+
+    /* if no promotion, return original cause */
+    return orig_cause;
+}
 /*
  * Handle Traps
  *
@@ -1751,6 +1767,7 @@ void riscv_cpu_do_interrupt(CPUState *cs)
     RISCVCPU *cpu = RISCV_CPU(cs);
     CPURISCVState *env = &cpu->env;
     bool write_gva = false;
+    bool always_storeamo = (env->excp_uw2 & RISCV_UW2_ALWAYS_STORE_AMO);
     uint64_t s;
 
     /*
@@ -1784,6 +1801,9 @@ void riscv_cpu_do_interrupt(CPUState *cs)
         case RISCV_EXCP_STORE_AMO_ACCESS_FAULT:
         case RISCV_EXCP_LOAD_PAGE_FAULT:
         case RISCV_EXCP_STORE_PAGE_FAULT:
+            if (always_storeamo) {
+                cause = promote_load_fault(cause);
+            }
             write_gva = env->two_stage_lookup;
             tval = env->badaddr;
             if (env->two_stage_indirect_lookup) {
diff --git a/target/riscv/tcg/tcg-cpu.c b/target/riscv/tcg/tcg-cpu.c
index 4da26cb926..83771303a8 100644
--- a/target/riscv/tcg/tcg-cpu.c
+++ b/target/riscv/tcg/tcg-cpu.c
@@ -129,6 +129,7 @@ static void riscv_restore_state_to_opc(CPUState *cs,
         env->pc = pc;
     }
     env->bins = data[1];
+    env->excp_uw2 = data[2];
 }
 
 static const TCGCPUOps riscv_tcg_ops = {
diff --git a/target/riscv/translate.c b/target/riscv/translate.c
index b1d251e893..16fff70dac 100644
--- a/target/riscv/translate.c
+++ b/target/riscv/translate.c
@@ -1265,7 +1265,7 @@ static void riscv_tr_insn_start(DisasContextBase *dcbase, CPUState *cpu)
         pc_next &= ~TARGET_PAGE_MASK;
     }
 
-    tcg_gen_insn_start(pc_next, 0);
+    tcg_gen_insn_start(pc_next, 0, 0);
     ctx->insn_start_updated = false;
 }
 
-- 
2.44.0