Add Nios II semihosting support. (413a99a9) · Commits · SUMMER2020 / students / proj-2021291

qemu-options.hx

+4 −4

Original line number	Diff line number	Diff line
		@@ -3968,21 +3968,21 @@ ETEXI
		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_MIPS \| QEMU_ARCH_NIOS2)
		STEXI
		@item -semihosting
		@findex -semihosting
		Enable semihosting mode (ARM, M68K, Xtensa, MIPS only).
		Enable semihosting mode (ARM, M68K, Xtensa, MIPS, Nios II only).
		ETEXI
		DEF("semihosting-config", HAS_ARG, QEMU_OPTION_semihosting_config,
		"-semihosting-config [enable=on\|off][,target=native\|gdb\|auto][,arg=str[,...]]\n" \
		" semihosting configuration\n",
		QEMU_ARCH_ARM \| QEMU_ARCH_M68K \| QEMU_ARCH_XTENSA \| QEMU_ARCH_LM32 \|
		QEMU_ARCH_MIPS)
		QEMU_ARCH_MIPS \| QEMU_ARCH_NIOS2)
		STEXI
		@item -semihosting-config [enable=on\|off][,target=native\|gdb\|auto][,arg=str[,...]]
		@findex -semihosting-config
		Enable and configure semihosting (ARM, M68K, Xtensa, MIPS only).
		Enable and configure semihosting (ARM, M68K, Xtensa, MIPS, Nios II only).
		@table @option
		@item target=@code{native\|gdb\|auto}
		Defines where the semihosting calls will be addressed, to QEMU (@code{native})

target/nios2/Makefile.objs

+1 −1

Original line number	Diff line number	Diff line
		obj-y += translate.o op_helper.o helper.o cpu.o mmu.o
		obj-y += translate.o op_helper.o helper.o cpu.o mmu.o nios2-semi.o
		obj-$(CONFIG_SOFTMMU) += monitor.o

		$(obj)/op_helper.o: QEMU_CFLAGS += $(HELPER_CFLAGS)

target/nios2/cpu.h

+3 −1

Original line number	Diff line number	Diff line
		@@ -141,7 +141,7 @@ typedef struct Nios2CPUClass {
		#define R_PC 64

		/* Exceptions */
		#define EXCP_BREAK -1
		#define EXCP_BREAK 0x1000
		#define EXCP_RESET 0
		#define EXCP_PRESET 1
		#define EXCP_IRQ 2
		@@ -222,6 +222,8 @@ void nios2_cpu_do_unaligned_access(CPUState *cpu, vaddr addr,
		qemu_irq nios2_cpu_pic_init(Nios2CPU cpu);
		void nios2_check_interrupts(CPUNios2State *env);

		void do_nios2_semihosting(CPUNios2State *env);

		#define TARGET_PHYS_ADDR_SPACE_BITS 32
		#ifdef CONFIG_USER_ONLY
		# define TARGET_VIRT_ADDR_SPACE_BITS 31

target/nios2/helper.c

+13 −0

Original line number	Diff line number	Diff line
		@@ -23,8 +23,10 @@
		#include "cpu.h"
		#include "qemu/host-utils.h"
		#include "exec/exec-all.h"
		#include "exec/cpu_ldst.h"
		#include "exec/log.h"
		#include "exec/helper-proto.h"
		#include "exec/semihost.h"

		#if defined(CONFIG_USER_ONLY)

		@@ -169,6 +171,17 @@ void nios2_cpu_do_interrupt(CPUState *cs)
		break;

		case EXCP_BREAK:
		qemu_log_mask(CPU_LOG_INT, "BREAK exception at pc=%x\n",
		env->regs[R_PC]);
		/* The semihosting instruction is "break 1". */
		if (semihosting_enabled() &&
		cpu_ldl_code(env, env->regs[R_PC]) == 0x003da07a) {
		qemu_log_mask(CPU_LOG_INT, "Entering semihosting\n");
		env->regs[R_PC] += 4;
		do_nios2_semihosting(env);
		break;
		}

		if ((env->regs[CR_STATUS] & CR_STATUS_EH) == 0) {
		env->regs[CR_BSTATUS] = env->regs[CR_STATUS];
		env->regs[R_BA] = env->regs[R_PC] + 4;

target/nios2/nios2-semi.c

0 → 100644

+455 −0

Original line number	Diff line number	Diff line
		/*
		* Nios II Semihosting syscall interface.
		* This code is derived from m68k-semi.c.
		* The semihosting protocol implemented here is described in the
		* libgloss sources:
		* https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;a=blob;f=libgloss/nios2/nios2-semi.txt;hb=HEAD
		*
		* Copyright (c) 2017-2019 Mentor Graphics
		*
		* This program is free software; you can redistribute it and/or modify
		* it under the terms of the GNU General Public License as published by
		* the Free Software Foundation; either version 2 of the License, or
		* (at your option) any later version.
		*
		* This program is distributed in the hope that it will be useful,
		* but WITHOUT ANY WARRANTY; without even the implied warranty of
		* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
		* GNU General Public License for more details.
		*
		* You should have received a copy of the GNU General Public License
		* along with this program; if not, see <http://www.gnu.org/licenses/>.
		*/

		#include "qemu/osdep.h"

		#include "cpu.h"
		#if defined(CONFIG_USER_ONLY)
		#include "qemu.h"
		#else
		#include "qemu-common.h"
		#include "exec/gdbstub.h"
		#include "exec/softmmu-semi.h"
		#endif
		#include "qemu/log.h"
		#include "sysemu/sysemu.h"

		#define HOSTED_EXIT 0
		#define HOSTED_INIT_SIM 1
		#define HOSTED_OPEN 2
		#define HOSTED_CLOSE 3
		#define HOSTED_READ 4
		#define HOSTED_WRITE 5
		#define HOSTED_LSEEK 6
		#define HOSTED_RENAME 7
		#define HOSTED_UNLINK 8
		#define HOSTED_STAT 9
		#define HOSTED_FSTAT 10
		#define HOSTED_GETTIMEOFDAY 11
		#define HOSTED_ISATTY 12
		#define HOSTED_SYSTEM 13

		typedef uint32_t gdb_mode_t;
		typedef uint32_t gdb_time_t;

		struct nios2_gdb_stat {
		uint32_t gdb_st_dev; /* device */
		uint32_t gdb_st_ino; /* inode */
		gdb_mode_t gdb_st_mode; /* protection */
		uint32_t gdb_st_nlink; /* number of hard links */
		uint32_t gdb_st_uid; /* user ID of owner */
		uint32_t gdb_st_gid; /* group ID of owner */
		uint32_t gdb_st_rdev; /* device type (if inode device) */
		uint64_t gdb_st_size; /* total size, in bytes */
		uint64_t gdb_st_blksize; /* blocksize for filesystem I/O */
		uint64_t gdb_st_blocks; /* number of blocks allocated */
		gdb_time_t gdb_st_atime; /* time of last access */
		gdb_time_t gdb_st_mtime; /* time of last modification */
		gdb_time_t gdb_st_ctime; /* time of last change */
		} QEMU_PACKED;

		struct gdb_timeval {
		gdb_time_t tv_sec; /* second */
		uint64_t tv_usec; /* microsecond */
		} QEMU_PACKED;

		#define GDB_O_RDONLY 0x0
		#define GDB_O_WRONLY 0x1
		#define GDB_O_RDWR 0x2
		#define GDB_O_APPEND 0x8
		#define GDB_O_CREAT 0x200
		#define GDB_O_TRUNC 0x400
		#define GDB_O_EXCL 0x800

		static int translate_openflags(int flags)
		{
		int hf;

		if (flags & GDB_O_WRONLY) {
		hf = O_WRONLY;
		} else if (flags & GDB_O_RDWR) {
		hf = O_RDWR;
		} else {
		hf = O_RDONLY;
		}

		if (flags & GDB_O_APPEND) {
		hf \|= O_APPEND;
		}
		if (flags & GDB_O_CREAT) {
		hf \|= O_CREAT;
		}
		if (flags & GDB_O_TRUNC) {
		hf \|= O_TRUNC;
		}
		if (flags & GDB_O_EXCL) {
		hf \|= O_EXCL;
		}

		return hf;
		}

		static bool translate_stat(CPUNios2State *env, target_ulong addr,
		struct stat *s)
		{
		struct nios2_gdb_stat *p;

		p = lock_user(VERIFY_WRITE, addr, sizeof(struct nios2_gdb_stat), 0);

		if (!p) {
		return false;
		}
		p->gdb_st_dev = cpu_to_be32(s->st_dev);
		p->gdb_st_ino = cpu_to_be32(s->st_ino);
		p->gdb_st_mode = cpu_to_be32(s->st_mode);
		p->gdb_st_nlink = cpu_to_be32(s->st_nlink);
		p->gdb_st_uid = cpu_to_be32(s->st_uid);
		p->gdb_st_gid = cpu_to_be32(s->st_gid);
		p->gdb_st_rdev = cpu_to_be32(s->st_rdev);
		p->gdb_st_size = cpu_to_be64(s->st_size);
		#ifdef _WIN32
		/* Windows stat is missing some fields. */
		p->gdb_st_blksize = 0;
		p->gdb_st_blocks = 0;
		#else
		p->gdb_st_blksize = cpu_to_be64(s->st_blksize);
		p->gdb_st_blocks = cpu_to_be64(s->st_blocks);
		#endif
		p->gdb_st_atime = cpu_to_be32(s->st_atime);
		p->gdb_st_mtime = cpu_to_be32(s->st_mtime);
		p->gdb_st_ctime = cpu_to_be32(s->st_ctime);
		unlock_user(p, addr, sizeof(struct nios2_gdb_stat));
		return true;
		}

		static void nios2_semi_return_u32(CPUNios2State *env, uint32_t ret,
		uint32_t err)
		{
		target_ulong args = env->regs[R_ARG1];
		if (put_user_u32(ret, args) \|\|
		put_user_u32(err, args + 4)) {
		/*
		* The nios2 semihosting ABI does not provide any way to report this
		* error to the guest, so the best we can do is log it in qemu.
		* It is always a guest error not to pass us a valid argument block.
		*/
		qemu_log_mask(LOG_GUEST_ERROR, "nios2-semihosting: return value "
		"discarded because argument block not writable\n");
		}
		}

		static void nios2_semi_return_u64(CPUNios2State *env, uint64_t ret,
		uint32_t err)
		{
		target_ulong args = env->regs[R_ARG1];
		if (put_user_u32(ret >> 32, args) \|\|
		put_user_u32(ret, args + 4) \|\|
		put_user_u32(err, args + 8)) {
		/* No way to report this via nios2 semihosting ABI; just log it */
		qemu_log_mask(LOG_GUEST_ERROR, "nios2-semihosting: return value "
		"discarded because argument block not writable\n");
		}
		}

		static int nios2_semi_is_lseek;

		static void nios2_semi_cb(CPUState *cs, target_ulong ret, target_ulong err)
		{
		Nios2CPU *cpu = NIOS2_CPU(cs);
		CPUNios2State *env = &cpu->env;

		if (nios2_semi_is_lseek) {
		/*
		* FIXME: We've already lost the high bits of the lseek
		* return value.
		*/
		nios2_semi_return_u64(env, ret, err);
		nios2_semi_is_lseek = 0;
		} else {
		nios2_semi_return_u32(env, ret, err);
		}
		}

		/*
		* Read the input value from the argument block; fail the semihosting
		* call if the memory read fails.
		*/
		#define GET_ARG(n) do { \
		if (get_user_ual(arg ## n, args + (n) * 4)) { \
		result = -1; \
		errno = EFAULT; \
		goto failed; \
		} \
		} while (0)

		void do_nios2_semihosting(CPUNios2State *env)
		{
		int nr;
		uint32_t args;
		target_ulong arg0, arg1, arg2, arg3;
		void *p;
		void *q;
		uint32_t len;
		uint32_t result;

		nr = env->regs[R_ARG0];
		args = env->regs[R_ARG1];
		switch (nr) {
		case HOSTED_EXIT:
		gdb_exit(env, env->regs[R_ARG0]);
		exit(env->regs[R_ARG0]);
		case HOSTED_OPEN:
		GET_ARG(0);
		GET_ARG(1);
		GET_ARG(2);
		GET_ARG(3);
		if (use_gdb_syscalls()) {
		gdb_do_syscall(nios2_semi_cb, "open,%s,%x,%x", arg0, (int)arg1,
		arg2, arg3);
		return;
		} else {
		p = lock_user_string(arg0);
		if (!p) {
		result = -1;
		errno = EFAULT;
		} else {
		result = open(p, translate_openflags(arg2), arg3);
		unlock_user(p, arg0, 0);
		}
		}
		break;
		case HOSTED_CLOSE:
		{
		/* Ignore attempts to close stdin/out/err. */
		GET_ARG(0);
		int fd = arg0;
		if (fd > 2) {
		if (use_gdb_syscalls()) {
		gdb_do_syscall(nios2_semi_cb, "close,%x", arg0);
		return;
		} else {
		result = close(fd);
		}
		} else {
		result = 0;
		}
		break;
		}
		case HOSTED_READ:
		GET_ARG(0);
		GET_ARG(1);
		GET_ARG(2);
		len = arg2;
		if (use_gdb_syscalls()) {
		gdb_do_syscall(nios2_semi_cb, "read,%x,%x,%x",
		arg0, arg1, len);
		return;
		} else {
		p = lock_user(VERIFY_WRITE, arg1, len, 0);
		if (!p) {
		result = -1;
		errno = EFAULT;
		} else {
		result = read(arg0, p, len);
		unlock_user(p, arg1, len);
		}
		}
		break;
		case HOSTED_WRITE:
		GET_ARG(0);
		GET_ARG(1);
		GET_ARG(2);
		len = arg2;
		if (use_gdb_syscalls()) {
		gdb_do_syscall(nios2_semi_cb, "write,%x,%x,%x",
		arg0, arg1, len);
		return;
		} else {
		p = lock_user(VERIFY_READ, arg1, len, 1);
		if (!p) {
		result = -1;
		errno = EFAULT;
		} else {
		result = write(arg0, p, len);
		unlock_user(p, arg0, 0);
		}
		}
		break;
		case HOSTED_LSEEK:
		{
		uint64_t off;
		GET_ARG(0);
		GET_ARG(1);
		GET_ARG(2);
		GET_ARG(3);
		off = (uint32_t)arg2 \| ((uint64_t)arg1 << 32);
		if (use_gdb_syscalls()) {
		nios2_semi_is_lseek = 1;
		gdb_do_syscall(nios2_semi_cb, "lseek,%x,%lx,%x",
		arg0, off, arg3);
		} else {
		off = lseek(arg0, off, arg3);
		nios2_semi_return_u64(env, off, errno);
		}
		return;
		}
		case HOSTED_RENAME:
		GET_ARG(0);
		GET_ARG(1);
		GET_ARG(2);
		GET_ARG(3);
		if (use_gdb_syscalls()) {
		gdb_do_syscall(nios2_semi_cb, "rename,%s,%s",
		arg0, (int)arg1, arg2, (int)arg3);
		return;
		} else {
		p = lock_user_string(arg0);
		q = lock_user_string(arg2);
		if (!p \|\| !q) {
		result = -1;
		errno = EFAULT;
		} else {
		result = rename(p, q);
		}
		unlock_user(p, arg0, 0);
		unlock_user(q, arg2, 0);
		}
		break;
		case HOSTED_UNLINK:
		GET_ARG(0);
		GET_ARG(1);
		if (use_gdb_syscalls()) {
		gdb_do_syscall(nios2_semi_cb, "unlink,%s",
		arg0, (int)arg1);
		return;
		} else {
		p = lock_user_string(arg0);
		if (!p) {
		result = -1;
		errno = EFAULT;
		} else {
		result = unlink(p);
		unlock_user(p, arg0, 0);
		}
		}
		break;
		case HOSTED_STAT:
		GET_ARG(0);
		GET_ARG(1);
		GET_ARG(2);
		if (use_gdb_syscalls()) {
		gdb_do_syscall(nios2_semi_cb, "stat,%s,%x",
		arg0, (int)arg1, arg2);
		return;
		} else {
		struct stat s;
		p = lock_user_string(arg0);
		if (!p) {
		result = -1;
		errno = EFAULT;
		} else {
		result = stat(p, &s);
		unlock_user(p, arg0, 0);
		}
		if (result == 0 && !translate_stat(env, arg2, &s)) {
		result = -1;
		errno = EFAULT;
		}
		}
		break;
		case HOSTED_FSTAT:
		GET_ARG(0);
		GET_ARG(1);
		if (use_gdb_syscalls()) {
		gdb_do_syscall(nios2_semi_cb, "fstat,%x,%x",
		arg0, arg1);
		return;
		} else {
		struct stat s;
		result = fstat(arg0, &s);
		if (result == 0 && !translate_stat(env, arg1, &s)) {
		result = -1;
		errno = EFAULT;
		}
		}
		break;
		case HOSTED_GETTIMEOFDAY:
		/* Only the tv parameter is used. tz is assumed NULL. */
		GET_ARG(0);
		if (use_gdb_syscalls()) {
		gdb_do_syscall(nios2_semi_cb, "gettimeofday,%x,%x",
		arg0, 0);
		return;
		} else {
		qemu_timeval tv;
		struct gdb_timeval *p;
		result = qemu_gettimeofday(&tv);
		if (result != 0) {
		p = lock_user(VERIFY_WRITE, arg0, sizeof(struct gdb_timeval),
		0);
		if (!p) {
		result = -1;
		errno = EFAULT;
		} else {
		p->tv_sec = cpu_to_be32(tv.tv_sec);
		p->tv_usec = cpu_to_be64(tv.tv_usec);
		unlock_user(p, arg0, sizeof(struct gdb_timeval));
		}
		}
		}
		break;
		case HOSTED_ISATTY:
		GET_ARG(0);
		if (use_gdb_syscalls()) {
		gdb_do_syscall(nios2_semi_cb, "isatty,%x", arg0);
		return;
		} else {
		result = isatty(arg0);
		}
		break;
		case HOSTED_SYSTEM:
		GET_ARG(0);
		GET_ARG(1);
		if (use_gdb_syscalls()) {
		gdb_do_syscall(nios2_semi_cb, "system,%s",
		arg0, (int)arg1);
		return;
		} else {
		p = lock_user_string(arg0);
		if (!p) {
		result = -1;
		errno = EFAULT;
		} else {
		result = system(p);
		unlock_user(p, arg0, 0);
		}
		}
		break;
		default:
		qemu_log_mask(LOG_GUEST_ERROR, "nios2-semihosting: unsupported "
		"semihosting syscall %d\n", nr);
		result = 0;
		}
		failed:
		nios2_semi_return_u32(env, result, errno);
		}