target/riscv: Implement riscv_cpu_unassigned_access

This patch adds support for the riscv_cpu_unassigned_access call
and will raise a load or store access fault.

Signed-off-by: Michael Clark <mjc@sifive.com>
[Changes by AF:
 - Squash two patches and rewrite commit message
 - Set baddr to the access address
]
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

target/riscv/cpu.c

@@ -482,6 +482,7 @@ static void riscv_cpu_class_init(ObjectClass *c, void *data)
     cc->gdb_stop_before_watchpoint = true;
     cc->disas_set_info = riscv_cpu_disas_set_info;
 #ifndef CONFIG_USER_ONLY
+    cc->do_unassigned_access = riscv_cpu_unassigned_access;
     cc->do_unaligned_access = riscv_cpu_do_unaligned_access;
     cc->get_phys_page_debug = riscv_cpu_get_phys_page_debug;
 #endif

target/riscv/cpu.h

@@ -259,6 +259,8 @@ void  riscv_cpu_do_unaligned_access(CPUState *cs, vaddr addr,
 bool riscv_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
                         MMUAccessType access_type, int mmu_idx,
                         bool probe, uintptr_t retaddr);
+void riscv_cpu_unassigned_access(CPUState *cpu, hwaddr addr, bool is_write,
+                                 bool is_exec, int unused, unsigned size);
 char *riscv_isa_string(RISCVCPU *cpu);
 void riscv_cpu_list(void);
 

target/riscv/cpu_helper.c

@@ -375,6 +375,22 @@ hwaddr riscv_cpu_get_phys_page_debug(CPUState *cs, vaddr addr)
     return phys_addr;
 }
 
+void riscv_cpu_unassigned_access(CPUState *cs, hwaddr addr, bool is_write,
+                                 bool is_exec, int unused, unsigned size)
+{
+    RISCVCPU *cpu = RISCV_CPU(cs);
+    CPURISCVState *env = &cpu->env;
+
+    if (is_write) {
+        cs->exception_index = RISCV_EXCP_STORE_AMO_ACCESS_FAULT;
+    } else {
+        cs->exception_index = RISCV_EXCP_LOAD_ACCESS_FAULT;
+    }
+
+    env->badaddr = addr;
+    riscv_raise_exception(&cpu->env, cs->exception_index, GETPC());
+}
+
 void riscv_cpu_do_unaligned_access(CPUState *cs, vaddr addr,
                                    MMUAccessType access_type, int mmu_idx,
                                    uintptr_t retaddr)