[RFC PATCH v3 07/27] target/loongarch: Add LoongArch CSR instruction

[Xiaojuan Yang <yangxiaojuan@loongson.cn>]

This includes:
- CSRRD
- CSRWR
- CSRXCHG

Signed-off-by: Xiaojuan Yang <yangxiaojuan@loongson.cn>
Signed-off-by: Song Gao <gaosong@loongson.cn>
---
 target/loongarch/cpu.h                       |  88 +++++++++++++
 target/loongarch/csr_helper.c                | 112 +++++++++++++++++
 target/loongarch/disas.c                     |  15 +++
 target/loongarch/helper.h                    |   7 ++
 target/loongarch/insn_trans/trans_core.c.inc | 123 +++++++++++++++++++
 target/loongarch/insns.decode                |  13 ++
 target/loongarch/meson.build                 |   1 +
 target/loongarch/translate.c                 |   5 +
 8 files changed, 364 insertions(+)
 create mode 100644 target/loongarch/csr_helper.c
 create mode 100644 target/loongarch/insn_trans/trans_core.c.inc

diff --git a/target/loongarch/cpu.h b/target/loongarch/cpu.h
index 6bbd1ab764..307a185a51 100644
--- a/target/loongarch/cpu.h
+++ b/target/loongarch/cpu.h
@@ -260,6 +260,94 @@ struct CPULoongArchState {
 #endif
 };
 
+#define CSR_OFF(X)  \
+           [LOONGARCH_CSR_##X] = offsetof(CPULoongArchState, CSR_##X)
+#define CSR_OFF_ARRAY(X, N)  \
+           [LOONGARCH_CSR_##X(N)] = offsetof(CPULoongArchState, CSR_##X[N])
+
+static const int csr_offsets[] = {
+     CSR_OFF(CRMD),
+     CSR_OFF(PRMD),
+     CSR_OFF(EUEN),
+     CSR_OFF(MISC),
+     CSR_OFF(ECFG),
+     CSR_OFF(ESTAT),
+     CSR_OFF(ERA),
+     CSR_OFF(BADV),
+     CSR_OFF(BADI),
+     CSR_OFF(EENTRY),
+     CSR_OFF(TLBIDX),
+     CSR_OFF(TLBEHI),
+     CSR_OFF(TLBELO0),
+     CSR_OFF(TLBELO1),
+     CSR_OFF(ASID),
+     CSR_OFF(PGDL),
+     CSR_OFF(PGDH),
+     CSR_OFF(PGD),
+     CSR_OFF(PWCL),
+     CSR_OFF(PWCH),
+     CSR_OFF(STLBPS),
+     CSR_OFF(RVACFG),
+     CSR_OFF(CPUID),
+     CSR_OFF(PRCFG1),
+     CSR_OFF(PRCFG2),
+     CSR_OFF(PRCFG3),
+     CSR_OFF_ARRAY(SAVE, 0),
+     CSR_OFF_ARRAY(SAVE, 1),
+     CSR_OFF_ARRAY(SAVE, 2),
+     CSR_OFF_ARRAY(SAVE, 3),
+     CSR_OFF_ARRAY(SAVE, 4),
+     CSR_OFF_ARRAY(SAVE, 5),
+     CSR_OFF_ARRAY(SAVE, 6),
+     CSR_OFF_ARRAY(SAVE, 7),
+     CSR_OFF_ARRAY(SAVE, 8),
+     CSR_OFF_ARRAY(SAVE, 9),
+     CSR_OFF_ARRAY(SAVE, 10),
+     CSR_OFF_ARRAY(SAVE, 11),
+     CSR_OFF_ARRAY(SAVE, 12),
+     CSR_OFF_ARRAY(SAVE, 13),
+     CSR_OFF_ARRAY(SAVE, 14),
+     CSR_OFF_ARRAY(SAVE, 15),
+     CSR_OFF(TID),
+     CSR_OFF(TCFG),
+     CSR_OFF(TVAL),
+     CSR_OFF(CNTC),
+     CSR_OFF(TICLR),
+     CSR_OFF(LLBCTL),
+     CSR_OFF(IMPCTL1),
+     CSR_OFF(IMPCTL2),
+     CSR_OFF(TLBRENTRY),
+     CSR_OFF(TLBRBADV),
+     CSR_OFF(TLBRERA),
+     CSR_OFF(TLBRSAVE),
+     CSR_OFF(TLBRELO0),
+     CSR_OFF(TLBRELO1),
+     CSR_OFF(TLBREHI),
+     CSR_OFF(TLBRPRMD),
+     CSR_OFF(MERRCTL),
+     CSR_OFF(MERRINFO1),
+     CSR_OFF(MERRINFO2),
+     CSR_OFF(MERRENTRY),
+     CSR_OFF(MERRERA),
+     CSR_OFF(MERRSAVE),
+     CSR_OFF(CTAG),
+     CSR_OFF_ARRAY(DMW, 0),
+     CSR_OFF_ARRAY(DMW, 1),
+     CSR_OFF_ARRAY(DMW, 2),
+     CSR_OFF_ARRAY(DMW, 3),
+     CSR_OFF(DBG),
+     CSR_OFF(DERA),
+     CSR_OFF(DSAVE),
+};
+
+static inline int cpu_csr_offset(unsigned csr_num)
+{
+    if (csr_num < ARRAY_SIZE(csr_offsets)) {
+        return csr_offsets[csr_num];
+    }
+    return 0;
+}
+
 /**
  * LoongArchCPU:
  * @env: #CPULoongArchState
diff --git a/target/loongarch/csr_helper.c b/target/loongarch/csr_helper.c
new file mode 100644
index 0000000000..19c03295b0
--- /dev/null
+++ b/target/loongarch/csr_helper.c
@@ -0,0 +1,112 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * LoongArch emulation helpers for csr registers
+ *
+ * Copyright (c) 2021 Loongson Technology Corporation Limited
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/main-loop.h"
+#include "cpu.h"
+#include "internals.h"
+#include "qemu/host-utils.h"
+#include "exec/helper-proto.h"
+#include "exec/exec-all.h"
+#include "exec/cpu_ldst.h"
+#include "hw/irq.h"
+#include "cpu-csr.h"
+#include "hw/loongarch/loongarch.h"
+#include "tcg/tcg-ldst.h"
+
+target_ulong helper_csr_rdq(CPULoongArchState *env, uint64_t csr)
+{
+    LoongArchCPU *cpu;
+    int64_t v;
+
+    switch (csr) {
+    case LOONGARCH_CSR_PGD:
+        if (env->CSR_TLBRERA & 0x1) {
+            v = env->CSR_TLBRBADV;
+        } else {
+            v = env->CSR_BADV;
+        }
+
+        if ((v >> 63) & 0x1) {
+            v = env->CSR_PGDH;
+        } else {
+            v = env->CSR_PGDL;
+        }
+        break;
+    case LOONGARCH_CSR_CPUID:
+        v = (env_cpu(env))->cpu_index;
+        break;
+    case LOONGARCH_CSR_TVAL:
+        cpu = LOONGARCH_CPU(env_cpu(env));
+        v = cpu_loongarch_get_stable_timer_ticks(cpu);
+        break;
+    default:
+        break;
+    }
+
+    return v;
+}
+
+target_ulong helper_csr_wrq(CPULoongArchState *env, target_ulong val,
+                            uint64_t csr)
+{
+    LoongArchCPU *cpu;
+    int64_t old_v = -1;
+
+    switch (csr) {
+    case LOONGARCH_CSR_ESTAT:
+        /* Only IS[1:0] can be write */
+        env->CSR_ESTAT = FIELD_DP64(env->CSR_ESTAT, CSR_ESTAT, IS, val & 0x3);
+        break;
+    case LOONGARCH_CSR_ASID:
+        old_v = env->CSR_ASID;
+        /* Only ASID filed of CSR_ASID can be write. */
+        env->CSR_ASID = FIELD_DP64(env->CSR_ASID, CSR_ASID, ASID,
+                                   val & R_CSR_ASID_ASID_MASK);
+        if (old_v != val) {
+            tlb_flush(env_cpu(env));
+        }
+        break;
+    case LOONGARCH_CSR_TCFG:
+        cpu = LOONGARCH_CPU(env_cpu(env));
+        old_v = env->CSR_TCFG;
+        cpu_loongarch_store_stable_timer_config(cpu, val);
+        break;
+    case LOONGARCH_CSR_TICLR:
+        old_v = 0;
+        env->CSR_ESTAT &= ~(1 << IRQ_TIMER);
+        cpu_reset_interrupt(env_cpu(env), CPU_INTERRUPT_HARD);
+        break;
+    default:
+        break;
+    }
+
+    return old_v;
+}
+
+target_ulong helper_csr_xchgq(CPULoongArchState *env, target_ulong new_val,
+                              target_ulong mask, uint64_t csr_num)
+{
+    unsigned csr_offset = cpu_csr_offset(csr_num);
+    if (csr_offset == 0) {
+        /* CSR is undefined: read as 0, write ignored. */
+        return 0;
+    }
+
+    uint64_t *csr = (void *)env + csr_offset;
+    uint64_t old_val = *csr;
+
+    new_val = (new_val & mask) | (old_val & ~mask);
+
+    if (csr_num == LOONGARCH_CSR_TCFG) {
+        LoongArchCPU *cpu = LOONGARCH_CPU(env_cpu(env));
+        cpu_loongarch_store_stable_timer_config(cpu, new_val);
+    } else {
+        *csr = new_val;
+    }
+    return old_val;
+}
diff --git a/target/loongarch/disas.c b/target/loongarch/disas.c
index 45be34de27..de683bb88b 100644
--- a/target/loongarch/disas.c
+++ b/target/loongarch/disas.c
@@ -204,6 +204,18 @@ static void output_rr_offs(DisasContext *ctx, arg_rr_offs *a,
     output(ctx, mnemonic, "r%d, r%d, %d", a->rj, a->rd, a->offs);
 }
 
+static void output_r_csr(DisasContext *ctx, arg_r_csr *a,
+                         const char *mnemonic)
+{
+    output(ctx, mnemonic, "r%d, %d", a->rd, a->csr);
+}
+
+static void output_rr_csr(DisasContext *ctx, arg_rr_csr *a,
+                          const char *mnemonic)
+{
+    output(ctx, mnemonic, "r%d, r%d, %d", a->rd, a->rj, a->csr);
+}
+
 #define INSN(insn, type)                                    \
 static bool trans_##insn(DisasContext *ctx, arg_##type * a) \
 {                                                           \
@@ -516,6 +528,9 @@ INSN(blt,          rr_offs)
 INSN(bge,          rr_offs)
 INSN(bltu,         rr_offs)
 INSN(bgeu,         rr_offs)
+INSN(csrrd,        r_csr)
+INSN(csrwr,        r_csr)
+INSN(csrxchg,      rr_csr)
 
 #define output_fcmp(C, PREFIX, SUFFIX)                                         \
 {                                                                              \
diff --git a/target/loongarch/helper.h b/target/loongarch/helper.h
index da1a2bced7..036dbf31f8 100644
--- a/target/loongarch/helper.h
+++ b/target/loongarch/helper.h
@@ -92,3 +92,10 @@ DEF_HELPER_2(frint_s, i64, env, i64)
 DEF_HELPER_2(frint_d, i64, env, i64)
 
 DEF_HELPER_FLAGS_2(set_rounding_mode, TCG_CALL_NO_RWG, void, env, i32)
+
+/*Core functions */
+#ifndef CONFIG_USER_ONLY
+DEF_HELPER_2(csr_rdq, i64, env, i64)
+DEF_HELPER_3(csr_wrq, i64, env, tl, i64)
+DEF_HELPER_4(csr_xchgq, i64, env, tl, tl, i64)
+#endif /* !CONFIG_USER_ONLY */
diff --git a/target/loongarch/insn_trans/trans_core.c.inc b/target/loongarch/insn_trans/trans_core.c.inc
new file mode 100644
index 0000000000..7d2cfe3534
--- /dev/null
+++ b/target/loongarch/insn_trans/trans_core.c.inc
@@ -0,0 +1,123 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * LoongArch translate functions for system mode
+ *
+ * Copyright (c) 2021 Loongson Technology Corporation Limited
+ */
+
+/* Privileged instruction translation */
+
+#include "cpu-csr.h"
+
+#ifdef CONFIG_USER_ONLY
+
+#define GEN_FALSE_TRANS(name)   \
+static bool trans_##name(DisasContext *ctx, arg_##name * a)  \
+{   \
+    return false;   \
+}
+
+GEN_FALSE_TRANS(csrrd)
+GEN_FALSE_TRANS(csrwr)
+GEN_FALSE_TRANS(csrxchg)
+
+#else
+
+static bool check_plv(DisasContext *ctx)
+{
+    if (ctx->base.tb->flags == MMU_USER_IDX) {
+        generate_exception(ctx, EXCCODE_IPE);
+        return true;
+    }
+    return false;
+}
+
+static bool ro_csr(int csr_num)
+{
+    /*
+     * For now qemu does not support any features of the MISC
+     * bits yet treat as a RO CSR.
+     */
+    if ((csr_num == LOONGARCH_CSR_BADI) || (csr_num == LOONGARCH_CSR_CPUID) ||
+        (csr_num == LOONGARCH_CSR_PRCFG1) || (csr_num == LOONGARCH_CSR_PRCFG2) ||
+        (csr_num == LOONGARCH_CSR_PRCFG3) || (csr_num == LOONGARCH_CSR_PGD) ||
+        (csr_num == LOONGARCH_CSR_TVAL) || (csr_num == LOONGARCH_CSR_MISC)) {
+        return true;
+    }
+
+    return false;
+}
+
+static bool trans_csrrd(DisasContext *ctx, arg_csrrd *a)
+{
+    TCGv dest = gpr_dst(ctx, a->rd, EXT_NONE);
+
+    if (check_plv(ctx)) {
+        return false;
+    }
+
+    unsigned csr_offset = cpu_csr_offset(a->csr);
+    if (csr_offset == 0) {
+        /* CSR is undefined: read as 0 */
+        dest = tcg_constant_tl(0);
+        return true;
+    }
+
+    if ((a->csr == LOONGARCH_CSR_PGD) || (a->csr == LOONGARCH_CSR_CPUID) ||
+        (a->csr == LOONGARCH_CSR_TVAL)) {
+        gen_helper_csr_rdq(dest, cpu_env, tcg_constant_i64(a->csr));
+    } else {
+        tcg_gen_ld_tl(dest, cpu_env, csr_offset);
+    }
+    return true;
+}
+
+static bool trans_csrwr(DisasContext *ctx, arg_csrwr *a)
+{
+    TCGv dest = gpr_dst(ctx, a->rd, EXT_NONE);
+    TCGv src1 = gpr_src(ctx, a->rd, EXT_NONE);
+
+    if (check_plv(ctx) || ro_csr(a->csr)) {
+        return false;
+    }
+
+    unsigned csr_offset = cpu_csr_offset(a->csr);
+    if (csr_offset == 0) {
+        /* CSR is undefined: write ignored. */
+        return true;
+    }
+
+    if ((a->csr == LOONGARCH_CSR_ASID) || (a->csr == LOONGARCH_CSR_TCFG) ||
+        (a->csr == LOONGARCH_CSR_TICLR) || (a->csr == LOONGARCH_CSR_ESTAT)) {
+        gen_helper_csr_wrq(dest, cpu_env, src1, tcg_constant_i64(a->csr));
+    } else {
+        TCGv temp = tcg_temp_new();
+        tcg_gen_ld_tl(temp, cpu_env, csr_offset);
+        tcg_gen_st_tl(src1, cpu_env, csr_offset);
+        tcg_gen_mov_tl(dest, temp);
+        tcg_temp_free(temp);
+
+        /* Cpu state may be changed, need exit */
+        if ((a->csr == LOONGARCH_CSR_CRMD) || (a->csr == LOONGARCH_CSR_EUEN)) {
+            tcg_gen_movi_tl(cpu_pc, ctx->base.pc_next + 4);
+            ctx->base.is_jmp = DISAS_EXIT;
+        }
+    }
+
+    return true;
+}
+
+static bool trans_csrxchg(DisasContext *ctx, arg_csrxchg *a)
+{
+    TCGv dest = gpr_dst(ctx, a->rd, EXT_NONE);
+    TCGv src1 = gpr_src(ctx, a->rd, EXT_NONE);
+    TCGv src2 = gpr_src(ctx, a->rj, EXT_NONE);
+
+    if (check_plv(ctx) || ro_csr(a->csr)) {
+        return false;
+    }
+    gen_helper_csr_xchgq(dest, cpu_env, src1, src2, tcg_constant_i64(a->csr));
+    return true;
+}
+
+#endif
diff --git a/target/loongarch/insns.decode b/target/loongarch/insns.decode
index 3379d22979..647fcb9def 100644
--- a/target/loongarch/insns.decode
+++ b/target/loongarch/insns.decode
@@ -45,6 +45,8 @@
 &c_offs       cj offs
 &offs         offs
 &rr_offs      rj rd offs
+&r_csr        rd csr
+&rr_csr       rd rj csr
 
 #
 # Formats
@@ -85,6 +87,8 @@
 @c_offs21      .... .. ................ .. cj:3 .....    &c_offs      offs=%offs21
 @offs26            .... .. ..........................    &offs        offs=%offs26
 @rr_offs16         .... .. ................ rj:5 rd:5    &rr_offs     offs=%offs16
+@r_csr                    .... .... csr:14 ..... rd:5    &r_csr
+@rr_csr                    .... .... csr:14 rj:5 rd:5    &rr_csr
 
 #
 # Fixed point arithmetic operation instruction
@@ -440,3 +444,12 @@ blt             0110 00 ................ ..... .....     @rr_offs16
 bge             0110 01 ................ ..... .....     @rr_offs16
 bltu            0110 10 ................ ..... .....     @rr_offs16
 bgeu            0110 11 ................ ..... .....     @rr_offs16
+
+#
+# Core instructions
+#
+{
+  csrrd             0000 0100 .............. 00000 .....     @r_csr
+  csrwr             0000 0100 .............. 00001 .....     @r_csr
+  csrxchg           0000 0100 .............. ..... .....     @rr_csr
+}
diff --git a/target/loongarch/meson.build b/target/loongarch/meson.build
index 935ffe2765..080d6297de 100644
--- a/target/loongarch/meson.build
+++ b/target/loongarch/meson.build
@@ -19,6 +19,7 @@ loongarch_softmmu_ss.add(files(
   'machine.c',
   'stabletimer.c',
   'tlb_helper.c',
+  'csr_helper.c',
 ))
 
 loongarch_ss.add_all(when: 'CONFIG_TCG', if_true: [loongarch_tcg_ss])
diff --git a/target/loongarch/translate.c b/target/loongarch/translate.c
index 2710764653..09771ee43f 100644
--- a/target/loongarch/translate.c
+++ b/target/loongarch/translate.c
@@ -26,6 +26,7 @@ TCGv_i32 cpu_fcsr0;
 TCGv_i64 cpu_fpr[32];
 
 #define DISAS_STOP       DISAS_TARGET_0
+#define DISAS_EXIT       DISAS_TARGET_1
 
 static inline int plus_1(DisasContext *ctx, int x)
 {
@@ -172,6 +173,7 @@ static void gen_set_gpr(int reg_num, TCGv t, DisasExtend dst_ext)
 #include "insn_trans/trans_fmov.c.inc"
 #include "insn_trans/trans_fmemory.c.inc"
 #include "insn_trans/trans_branch.c.inc"
+#include "insn_trans/trans_core.c.inc"
 
 static void loongarch_tr_translate_insn(DisasContextBase *dcbase, CPUState *cs)
 {
@@ -209,6 +211,9 @@ static void loongarch_tr_tb_stop(DisasContextBase *dcbase, CPUState *cs)
         break;
     case DISAS_NORETURN:
         break;
+    case DISAS_EXIT:
+        tcg_gen_exit_tb(NULL, 0);
+        break;
     default:
         g_assert_not_reached();
     }
-- 
2.27.0