[RESEND PATCH v3 5/7] target/riscv: csr: Hook debug CSR read/write

[Bin Meng <bmeng.cn@gmail.com>]

From: Bin Meng <bin.meng@windriver.com>

This adds debug CSR read/write support to the RISC-V CSR RW table.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
---

Changes in v3:
- add riscv_trigger_init(), moved from patch #1 to this patch

 target/riscv/debug.h |  2 ++
 target/riscv/cpu.c   |  6 +++++
 target/riscv/csr.c   | 57 ++++++++++++++++++++++++++++++++++++++++++++
 target/riscv/debug.c | 27 +++++++++++++++++++++
 4 files changed, 92 insertions(+)

diff --git a/target/riscv/debug.h b/target/riscv/debug.h
index d0f63e2414..f4da2db35d 100644
--- a/target/riscv/debug.h
+++ b/target/riscv/debug.h
@@ -109,4 +109,6 @@ void riscv_cpu_debug_excp_handler(CPUState *cs);
 bool riscv_cpu_debug_check_breakpoint(CPUState *cs);
 bool riscv_cpu_debug_check_watchpoint(CPUState *cs, CPUWatchpoint *wp);
 
+void riscv_trigger_init(CPURISCVState *env);
+
 #endif /* RISCV_DEBUG_H */
diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index d36c31ce9a..17dcc3c14f 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -575,6 +575,12 @@ static void riscv_cpu_realize(DeviceState *dev, Error **errp)
 
     riscv_cpu_register_gdb_regs_for_features(cs);
 
+#ifndef CONFIG_USER_ONLY
+    if (riscv_feature(env, RISCV_FEATURE_DEBUG)) {
+        riscv_trigger_init(env);
+    }
+#endif
+
     qemu_init_vcpu(cs);
     cpu_reset(cs);
 
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 146447eac5..189b9cc8c6 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -220,6 +220,15 @@ static RISCVException epmp(CPURISCVState *env, int csrno)
 
     return RISCV_EXCP_ILLEGAL_INST;
 }
+
+static RISCVException debug(CPURISCVState *env, int csrno)
+{
+    if (riscv_feature(env, RISCV_FEATURE_DEBUG)) {
+        return RISCV_EXCP_NONE;
+    }
+
+    return RISCV_EXCP_ILLEGAL_INST;
+}
 #endif
 
 /* User Floating-Point CSRs */
@@ -1464,6 +1473,48 @@ static RISCVException write_pmpaddr(CPURISCVState *env, int csrno,
     return RISCV_EXCP_NONE;
 }
 
+static RISCVException read_tselect(CPURISCVState *env, int csrno,
+                                   target_ulong *val)
+{
+    *val = tselect_csr_read(env);
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException write_tselect(CPURISCVState *env, int csrno,
+                                    target_ulong val)
+{
+    tselect_csr_write(env, val);
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException read_tdata(CPURISCVState *env, int csrno,
+                                 target_ulong *val)
+{
+    /* return 0 in tdata1 to end the trigger enumeration */
+    if (env->trigger_cur >= TRIGGER_NUM && csrno == CSR_TDATA1) {
+        *val = 0;
+        return RISCV_EXCP_NONE;
+    }
+
+    if (!tdata_available(env, csrno - CSR_TDATA1)) {
+        return RISCV_EXCP_ILLEGAL_INST;
+    }
+
+    *val = tdata_csr_read(env, csrno - CSR_TDATA1);
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException write_tdata(CPURISCVState *env, int csrno,
+                                  target_ulong val)
+{
+    if (!tdata_available(env, csrno - CSR_TDATA1)) {
+        return RISCV_EXCP_ILLEGAL_INST;
+    }
+
+    tdata_csr_write(env, csrno - CSR_TDATA1, val);
+    return RISCV_EXCP_NONE;
+}
+
 /*
  * Functions to access Pointer Masking feature registers
  * We have to check if current priv lvl could modify
@@ -1962,6 +2013,12 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
     [CSR_PMPADDR14] =  { "pmpaddr14", pmp, read_pmpaddr, write_pmpaddr },
     [CSR_PMPADDR15] =  { "pmpaddr15", pmp, read_pmpaddr, write_pmpaddr },
 
+    /* Debug CSRs */
+    [CSR_TSELECT]   =  { "tselect", debug, read_tselect, write_tselect },
+    [CSR_TDATA1]    =  { "tdata1",  debug, read_tdata,   write_tdata   },
+    [CSR_TDATA2]    =  { "tdata2",  debug, read_tdata,   write_tdata   },
+    [CSR_TDATA3]    =  { "tdata3",  debug, read_tdata,   write_tdata   },
+
     /* User Pointer Masking */
     [CSR_UMTE]    =    { "umte",    pointer_masking, read_umte,    write_umte    },
     [CSR_UPMMASK] =    { "upmmask", pointer_masking, read_upmmask, write_upmmask },
diff --git a/target/riscv/debug.c b/target/riscv/debug.c
index 7760c4611f..041a0d3a89 100644
--- a/target/riscv/debug.c
+++ b/target/riscv/debug.c
@@ -412,3 +412,30 @@ bool riscv_cpu_debug_check_watchpoint(CPUState *cs, CPUWatchpoint *wp)
 
     return false;
 }
+
+void riscv_trigger_init(CPURISCVState *env)
+{
+    target_ulong type2 = trigger_type(env, TRIGGER_TYPE_AD_MATCH);
+    int i;
+
+    /* type 2 triggers */
+    for (i = 0; i < TRIGGER_TYPE2_NUM; i++) {
+        /*
+         * type = TRIGGER_TYPE_AD_MATCH
+         * dmode = 0 (both debug and M-mode can write tdata)
+         * maskmax = 0 (unimplemented, always 0)
+         * sizehi = 0 (match against any size, RV64 only)
+         * hit = 0 (unimplemented, always 0)
+         * select = 0 (always 0, perform match on address)
+         * timing = 0 (always 0, trigger before instruction)
+         * sizelo = 0 (match against any size)
+         * action = 0 (always 0, raise a breakpoint exception)
+         * chain = 0 (unimplemented, always 0)
+         * match = 0 (always 0, when any compare value equals tdata2)
+         */
+        env->trigger_type2[i].mcontrol = type2;
+        env->trigger_type2[i].maddress = 0;
+        env->trigger_type2[i].bp = NULL;
+        env->trigger_type2[i].wp = NULL;
+    }
+}
-- 
2.25.1