Adapt the arm semihosting support code for RISCV. This implementation is based on the standard for RISC-V semihosting version 0.2 as documented in
https://github.com/riscv/riscv-semihosting-spec/releases/tag/0.2 Signed-off-by: Keith Packard <kei...@keithp.com> --- v2: Update PC after exception is handled to follow change in the ARM version for SYS_READC v3: Disallow semihosting in user mode; report a regular breakpoint in that case. v4: Fix errors reported by checkpatch v5: Reference current RISC-V semihosting specification v6: Add support for semihosting in riscv64-linux-user and riscv32-linux-user v7: Add meson build support v8: Fix errors reported by checkpatch that crept in. v9: Changes suggested by Alistair Francis <alistai...@gmail.com>: Don't add me to the MAINTAINERS file. Remove duplicate #include in target/riscv/cpu.h Reference RISC-V semihosting spec in target/riscv/riscv-semi.c v10: Use common semihosting implementation instead of a separate copy. Make sure addresses of the three breakpoint-signaling instructions all lie within the same page. Change suggested by Richard Henderson <richard.hender...@linaro.org> --- default-configs/devices/riscv32-softmmu.mak | 1 + default-configs/devices/riscv64-softmmu.mak | 1 + hw/semihosting/common-semi.c | 51 ++++++++++++++++++- hw/semihosting/common-semi.h | 5 +- hw/semihosting/meson.build | 2 + linux-user/meson.build | 3 ++ linux-user/qemu.h | 4 +- linux-user/semihost.c | 8 +-- qemu-options.hx | 10 ++-- target/riscv/cpu_bits.h | 1 + target/riscv/cpu_helper.c | 10 ++++ .../riscv/insn_trans/trans_privileged.c.inc | 37 +++++++++++++- target/riscv/translate.c | 11 ++++ 13 files changed, 132 insertions(+), 12 deletions(-) diff --git a/default-configs/devices/riscv32-softmmu.mak b/default-configs/devices/riscv32-softmmu.mak index 94a236c9c2..e8a4eeebec 100644 --- a/default-configs/devices/riscv32-softmmu.mak +++ b/default-configs/devices/riscv32-softmmu.mak @@ -3,6 +3,7 @@ # Uncomment the following lines to disable these optional devices: # #CONFIG_PCI_DEVICES=n +CONFIG_SEMIHOSTING=y # Boards: # diff --git a/default-configs/devices/riscv64-softmmu.mak b/default-configs/devices/riscv64-softmmu.mak index 76b6195648..d8a87b7671 100644 --- a/default-configs/devices/riscv64-softmmu.mak +++ b/default-configs/devices/riscv64-softmmu.mak @@ -3,6 +3,7 @@ # Uncomment the following lines to disable these optional devices: # #CONFIG_PCI_DEVICES=n +CONFIG_SEMIHOSTING=y # Boards: # diff --git a/hw/semihosting/common-semi.c b/hw/semihosting/common-semi.c index c77fb21bec..8675934a71 100644 --- a/hw/semihosting/common-semi.c +++ b/hw/semihosting/common-semi.c @@ -1,6 +1,6 @@ /* * Semihosting support for systems modeled on the Arm "Angel" - * semihosting syscalls design. + * semihosting syscalls design. This includes Arm and RISC-V processors * * Copyright (c) 2005, 2007 CodeSourcery. * Copyright (c) 2019 Linaro @@ -25,6 +25,10 @@ * ARM Semihosting is documented in: * Semihosting for AArch32 and AArch64 Release 2.0 * https://static.docs.arm.com/100863/0200/semihosting.pdf + * + * RISC-V Semihosting is documented in: + * RISC-V Semihosting + * https://github.com/riscv/riscv-semihosting-spec/blob/main/riscv-semihosting-spec.adoc */ #include "qemu/osdep.h" @@ -163,6 +167,30 @@ common_semi_sys_exit_extended(CPUState *cs, int nr) } #endif /* TARGET_ARM */ +#ifdef TARGET_RISCV +static inline target_ulong +common_semi_arg(CPUState *cs, int argno) +{ + RISCVCPU *cpu = RISCV_CPU(cs); + CPURISCVState *env = &cpu->env; + return env->gpr[xA0 + argno]; +} + +static inline void +common_semi_set_ret(CPUState *cs, target_ulong ret) +{ + RISCVCPU *cpu = RISCV_CPU(cs); + CPURISCVState *env = &cpu->env; + env->gpr[xA0] = ret; +} + +static inline bool +common_semi_sys_exit_extended(CPUState *cs, int nr) +{ + return (nr == TARGET_SYS_EXIT_EXTENDED || sizeof(target_ulong) == 0); +} +#endif + /* * Allocate a new guest file descriptor and return it; if we * couldn't allocate a new fd then return -1. @@ -339,6 +367,12 @@ static target_ulong common_semi_flen_buf(CPUState *cs) sp = env->regs[13]; } #endif +#ifdef TARGET_RISCV + RISCVCPU *cpu = RISCV_CPU(cs); + CPURISCVState *env = &cpu->env; + + sp = env->gpr[xSP]; +#endif return sp - 64; } @@ -678,6 +712,18 @@ static const GuestFDFunctions guestfd_fns[] = { put_user_u32(val, args + (n) * 4)) #endif +#ifdef TARGET_RISCV +#define GET_ARG(n) do { \ + if (get_user_ual(arg ## n, args + (n) * sizeof(target_ulong))) { \ + errno = EFAULT; \ + return set_swi_errno(cs, -1); \ + } \ + } while (0) + +#define SET_ARG(n, val) \ + put_user_ual(val, args + (n) * sizeof(target_ulong)) +#endif + /* * Do a semihosting call. * @@ -1112,6 +1158,9 @@ target_ulong do_common_semihosting(CPUState *cs) if (is_a64(cs->env_ptr)) { return 0; } +#endif +#ifdef TARGET_RISCV + return 0; #endif /* fall through -- invalid for A32/T32 */ default: diff --git a/hw/semihosting/common-semi.h b/hw/semihosting/common-semi.h index bc53e92c79..0bfab1c669 100644 --- a/hw/semihosting/common-semi.h +++ b/hw/semihosting/common-semi.h @@ -1,6 +1,6 @@ /* * Semihosting support for systems modeled on the Arm "Angel" - * semihosting syscalls design. + * semihosting syscalls design. This includes Arm and RISC-V processors * * Copyright (c) 2005, 2007 CodeSourcery. * Copyright (c) 2019 Linaro @@ -26,6 +26,9 @@ * Semihosting for AArch32 and AArch64 Release 2.0 * https://static.docs.arm.com/100863/0200/semihosting.pdf * + * RISC-V Semihosting is documented in: + * RISC-V Semihosting + * https://github.com/riscv/riscv-semihosting-spec/blob/main/riscv-semihosting-spec.adoc */ #ifndef COMMON_SEMI_H diff --git a/hw/semihosting/meson.build b/hw/semihosting/meson.build index fbd2841e59..48a6c9b3e5 100644 --- a/hw/semihosting/meson.build +++ b/hw/semihosting/meson.build @@ -4,3 +4,5 @@ specific_ss.add(when: 'CONFIG_SEMIHOSTING', if_true: files( )) specific_ss.add(when: 'CONFIG_TCG', if_true: files ('common-semi.c')) +specific_ss.add(when: 'TARGET_RISCV32', if_true: files ('common-semi.c')) +specific_ss.add(when: 'TARGET_RISCV64', if_true: files ('common-semi.c')) diff --git a/linux-user/meson.build b/linux-user/meson.build index 2fdd12cee5..68fce095fb 100644 --- a/linux-user/meson.build +++ b/linux-user/meson.build @@ -20,6 +20,9 @@ linux_user_ss.add(when: 'TARGET_I386', if_true: files('vm86.c')) linux_user_ss.add(when: 'TARGET_AARCH64', if_true: files('semihost.c')) linux_user_ss.add(when: 'TARGET_ARM', if_true: files('semihost.c')) +linux_user_ss.add(when: 'TARGET_RISCV64', if_true: files('semihost.c')) +linux_user_ss.add(when: 'TARGET_RISCV32', if_true: files('semihost.c')) + syscall_nr_generators = {} subdir('alpha') diff --git a/linux-user/qemu.h b/linux-user/qemu.h index 941ca99722..faeaab9614 100644 --- a/linux-user/qemu.h +++ b/linux-user/qemu.h @@ -105,6 +105,8 @@ typedef struct TaskState { /* FPA state */ FPA11 fpa; # endif +#endif +#if defined(TARGET_ARM) || defined(TARGET_RISCV) int swi_errno; #endif #if defined(TARGET_I386) && !defined(TARGET_X86_64) @@ -118,7 +120,7 @@ typedef struct TaskState { #ifdef TARGET_M68K abi_ulong tp_value; #endif -#if defined(TARGET_ARM) || defined(TARGET_M68K) +#if defined(TARGET_ARM) || defined(TARGET_M68K) || defined(TARGET_RISCV) /* Extra fields for semihosted binaries. */ abi_ulong heap_base; abi_ulong heap_limit; diff --git a/linux-user/semihost.c b/linux-user/semihost.c index a1f0f6050e..c0015ee7f6 100644 --- a/linux-user/semihost.c +++ b/linux-user/semihost.c @@ -1,11 +1,11 @@ /* - * ARM Semihosting Console Support + * ARM Compatible Semihosting Console Support. * * Copyright (c) 2019 Linaro Ltd * - * Currently ARM is unique in having support for semihosting support - * in linux-user. So for now we implement the common console API but - * just for arm linux-user. + * Currently ARM and RISC-V are unique in having support for + * semihosting support in linux-user. So for now we implement the + * common console API but just for arm and risc-v linux-user. * * SPDX-License-Identifier: GPL-2.0-or-later */ diff --git a/qemu-options.hx b/qemu-options.hx index 2c83390504..9a606946c4 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -4184,10 +4184,10 @@ ERST DEF("semihosting", 0, QEMU_OPTION_semihosting, "-semihosting semihosting mode\n", QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | QEMU_ARCH_LM32 | - QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2) + QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2 | QEMU_ARCH_RISCV) SRST ``-semihosting`` - Enable semihosting mode (ARM, M68K, Xtensa, MIPS, Nios II only). + Enable semihosting mode (ARM, M68K, Xtensa, MIPS, Nios II, RISC-V only). Note that this allows guest direct access to the host filesystem, so should only be used with a trusted guest OS. @@ -4199,10 +4199,10 @@ DEF("semihosting-config", HAS_ARG, QEMU_OPTION_semihosting_config, "-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]\n" \ " semihosting configuration\n", QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | QEMU_ARCH_LM32 | -QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2) +QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2 | QEMU_ARCH_RISCV) SRST ``-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]`` - Enable and configure semihosting (ARM, M68K, Xtensa, MIPS, Nios II + Enable and configure semihosting (ARM, M68K, Xtensa, MIPS, Nios II, RISC-V only). Note that this allows guest direct access to the host filesystem, so @@ -4217,6 +4217,8 @@ SRST open/read/write/seek/select. Tensilica baremetal libc for ISS and linux platform "sim" use this interface. + On RISC-V this implements the standard semihosting API, version 0.2. + ``target=native|gdb|auto`` Defines where the semihosting calls will be addressed, to QEMU (``native``) or to GDB (``gdb``). The default is ``auto``, which diff --git a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h index bd36062877..26a60b9e27 100644 --- a/target/riscv/cpu_bits.h +++ b/target/riscv/cpu_bits.h @@ -556,6 +556,7 @@ #define RISCV_EXCP_INST_PAGE_FAULT 0xc /* since: priv-1.10.0 */ #define RISCV_EXCP_LOAD_PAGE_FAULT 0xd /* since: priv-1.10.0 */ #define RISCV_EXCP_STORE_PAGE_FAULT 0xf /* since: priv-1.10.0 */ +#define RISCV_EXCP_SEMIHOST 0x10 #define RISCV_EXCP_INST_GUEST_PAGE_FAULT 0x14 #define RISCV_EXCP_LOAD_GUEST_ACCESS_FAULT 0x15 #define RISCV_EXCP_VIRT_INSTRUCTION_FAULT 0x16 diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c index 4652082df1..d71611ec02 100644 --- a/target/riscv/cpu_helper.c +++ b/target/riscv/cpu_helper.c @@ -24,6 +24,7 @@ #include "exec/exec-all.h" #include "tcg/tcg-op.h" #include "trace.h" +#include "hw/semihosting/common-semi.h" int riscv_cpu_mmu_index(CPURISCVState *env, bool ifetch) { @@ -875,6 +876,15 @@ void riscv_cpu_do_interrupt(CPUState *cs) target_ulong htval = 0; target_ulong mtval2 = 0; + if (cause == RISCV_EXCP_SEMIHOST) { + if (env->priv >= PRV_S) { + env->gpr[xA0] = do_common_semihosting(cs); + env->pc += 4; + return; + } + cause = RISCV_EXCP_BREAKPOINT; + } + if (!async) { /* set tval to badaddr for traps with address information */ switch (cause) { diff --git a/target/riscv/insn_trans/trans_privileged.c.inc b/target/riscv/insn_trans/trans_privileged.c.inc index 2a61a853bf..32312be202 100644 --- a/target/riscv/insn_trans/trans_privileged.c.inc +++ b/target/riscv/insn_trans/trans_privileged.c.inc @@ -29,7 +29,42 @@ static bool trans_ecall(DisasContext *ctx, arg_ecall *a) static bool trans_ebreak(DisasContext *ctx, arg_ebreak *a) { - generate_exception(ctx, RISCV_EXCP_BREAKPOINT); + target_ulong ebreak_addr = ctx->base.pc_next; + target_ulong pre_addr = ebreak_addr - 4; + target_ulong post_addr = ebreak_addr + 4; + uint32_t pre = 0; + uint32_t ebreak = 0; + uint32_t post = 0; + + /* + * The RISC-V semihosting spec specifies the following + * three-instruction sequence to flag a semihosting call: + * + * slli zero, zero, 0x1f 0x01f01013 + * ebreak 0x00100073 + * srai zero, zero, 0x7 0x40705013 + * + * The two shift operations on the zero register are no-ops, used + * here to signify a semihosting exception, rather than a breakpoint. + * + * Uncompressed instructions are required so that the sequence is easy + * to validate. + * + * The three instructions are required to lie in the same page so + * that no exception will be raised when fetching them. + */ + + if ((pre_addr & TARGET_PAGE_MASK) == (post_addr & TARGET_PAGE_MASK)) { + pre = opcode_at(&ctx->base, pre_addr); + ebreak = opcode_at(&ctx->base, ebreak_addr); + post = opcode_at(&ctx->base, post_addr); + } + + if (pre == 0x01f01013 && ebreak == 0x00100073 && post == 0x40705013) { + generate_exception(ctx, RISCV_EXCP_SEMIHOST); + } else { + generate_exception(ctx, RISCV_EXCP_BREAKPOINT); + } exit_tb(ctx); /* no chaining */ ctx->base.is_jmp = DISAS_NORETURN; return true; diff --git a/target/riscv/translate.c b/target/riscv/translate.c index 79dca2291b..ecf594babc 100644 --- a/target/riscv/translate.c +++ b/target/riscv/translate.c @@ -63,6 +63,7 @@ typedef struct DisasContext { uint16_t vlen; uint16_t mlen; bool vl_eq_vlmax; + CPUState *cs; } DisasContext; #ifdef TARGET_RISCV64 @@ -746,6 +747,15 @@ static bool gen_shift(DisasContext *ctx, arg_r *a, return true; } +static uint32_t opcode_at(DisasContextBase *dcbase, target_ulong pc) +{ + DisasContext *ctx = container_of(dcbase, DisasContext, base); + CPUState *cpu = ctx->cs; + CPURISCVState *env = cpu->env_ptr; + + return cpu_ldl_code(env, pc); +} + /* Include insn module translation function */ #include "insn_trans/trans_rvi.c.inc" #include "insn_trans/trans_rvm.c.inc" @@ -812,6 +822,7 @@ static void riscv_tr_init_disas_context(DisasContextBase *dcbase, CPUState *cs) ctx->lmul = FIELD_EX32(tb_flags, TB_FLAGS, LMUL); ctx->mlen = 1 << (ctx->sew + 3 - ctx->lmul); ctx->vl_eq_vlmax = FIELD_EX32(tb_flags, TB_FLAGS, VL_EQ_VLMAX); + ctx->cs = cs; } static void riscv_tr_tb_start(DisasContextBase *db, CPUState *cpu) -- 2.28.0
