1/*
2 * RISC-V translation routines for the RISC-V privileged instructions.
3 *
4 * Copyright (c) 2016-2017 Sagar Karandikar, sagark@eecs.berkeley.edu
5 * Copyright (c) 2018 Peer Adelt, peer.adelt@hni.uni-paderborn.de
6 *                    Bastian Koppelmann, kbastian@mail.uni-paderborn.de
7 *
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms and conditions of the GNU General Public License,
10 * version 2 or later, as published by the Free Software Foundation.
11 *
12 * This program is distributed in the hope it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
15 * more details.
16 *
17 * You should have received a copy of the GNU General Public License along with
18 * this program.  If not, see <http://www.gnu.org/licenses/>.
19 */
20
21static bool trans_ecall(DisasContext *ctx, arg_ecall *a)
22{
23    /* always generates U-level ECALL, fixed in do_interrupt handler */
24    generate_exception(ctx, RISCV_EXCP_U_ECALL);
25    return true;
26}
27
28static bool trans_ebreak(DisasContext *ctx, arg_ebreak *a)
29{
30    target_ulong    ebreak_addr = ctx->base.pc_next;
31    target_ulong    pre_addr = ebreak_addr - 4;
32    target_ulong    post_addr = ebreak_addr + 4;
33    uint32_t pre    = 0;
34    uint32_t ebreak = 0;
35    uint32_t post   = 0;
36
37    /*
38     * The RISC-V semihosting spec specifies the following
39     * three-instruction sequence to flag a semihosting call:
40     *
41     *      slli zero, zero, 0x1f       0x01f01013
42     *      ebreak                      0x00100073
43     *      srai zero, zero, 0x7        0x40705013
44     *
45     * The two shift operations on the zero register are no-ops, used
46     * here to signify a semihosting exception, rather than a breakpoint.
47     *
48     * Uncompressed instructions are required so that the sequence is easy
49     * to validate.
50     *
51     * The three instructions are required to lie in the same page so
52     * that no exception will be raised when fetching them.
53     */
54
55    if (semihosting_enabled(ctx->priv == PRV_U) &&
56        (pre_addr & TARGET_PAGE_MASK) == (post_addr & TARGET_PAGE_MASK)) {
57        pre    = opcode_at(&ctx->base, pre_addr);
58        ebreak = opcode_at(&ctx->base, ebreak_addr);
59        post   = opcode_at(&ctx->base, post_addr);
60    }
61
62    if (pre == 0x01f01013 && ebreak == 0x00100073 && post == 0x40705013) {
63        generate_exception(ctx, RISCV_EXCP_SEMIHOST);
64    } else {
65        generate_exception(ctx, RISCV_EXCP_BREAKPOINT);
66    }
67    return true;
68}
69
70static bool trans_uret(DisasContext *ctx, arg_uret *a)
71{
72    return false;
73}
74
75static bool trans_sret(DisasContext *ctx, arg_sret *a)
76{
77#ifndef CONFIG_USER_ONLY
78    if (has_ext(ctx, RVS)) {
79        decode_save_opc(ctx);
80        translator_io_start(&ctx->base);
81        gen_helper_sret(cpu_pc, cpu_env);
82        exit_tb(ctx); /* no chaining */
83        ctx->base.is_jmp = DISAS_NORETURN;
84    } else {
85        return false;
86    }
87    return true;
88#else
89    return false;
90#endif
91}
92
93static bool trans_mret(DisasContext *ctx, arg_mret *a)
94{
95#ifndef CONFIG_USER_ONLY
96    decode_save_opc(ctx);
97    translator_io_start(&ctx->base);
98    gen_helper_mret(cpu_pc, cpu_env);
99    exit_tb(ctx); /* no chaining */
100    ctx->base.is_jmp = DISAS_NORETURN;
101    return true;
102#else
103    return false;
104#endif
105}
106
107static bool trans_wfi(DisasContext *ctx, arg_wfi *a)
108{
109#ifndef CONFIG_USER_ONLY
110    decode_save_opc(ctx);
111    gen_update_pc(ctx, ctx->cur_insn_len);
112    gen_helper_wfi(cpu_env);
113    return true;
114#else
115    return false;
116#endif
117}
118
119static bool trans_sfence_vma(DisasContext *ctx, arg_sfence_vma *a)
120{
121#ifndef CONFIG_USER_ONLY
122    decode_save_opc(ctx);
123    gen_helper_tlb_flush(cpu_env);
124    return true;
125#endif
126    return false;
127}
128
129static bool trans_sfence_vm(DisasContext *ctx, arg_sfence_vm *a)
130{
131    return false;
132}
133