157 lines
3.7 KiB
C
157 lines
3.7 KiB
C
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/*
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* Syscall implementations for semihosting.
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*
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* Copyright (c) 2022 Linaro
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*
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* SPDX-License-Identifier: GPL-2.0-or-later
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*/
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#include "qemu/osdep.h"
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#include "exec/gdbstub.h"
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#include "semihosting/guestfd.h"
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#include "semihosting/syscalls.h"
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#ifdef CONFIG_USER_ONLY
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#include "qemu.h"
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#else
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#include "semihosting/softmmu-uaccess.h"
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#endif
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/*
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* Validate or compute the length of the string (including terminator).
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*/
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static int validate_strlen(CPUState *cs, target_ulong str, target_ulong tlen)
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{
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CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
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char c;
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if (tlen == 0) {
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ssize_t slen = target_strlen(str);
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if (slen < 0) {
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return -EFAULT;
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}
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if (slen >= INT32_MAX) {
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return -ENAMETOOLONG;
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}
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return slen + 1;
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}
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if (tlen > INT32_MAX) {
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return -ENAMETOOLONG;
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}
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if (get_user_u8(c, str + tlen - 1)) {
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return -EFAULT;
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}
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if (c != 0) {
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return -EINVAL;
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}
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return tlen;
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}
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static int validate_lock_user_string(char **pstr, CPUState *cs,
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target_ulong tstr, target_ulong tlen)
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{
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int ret = validate_strlen(cs, tstr, tlen);
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CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
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char *str = NULL;
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if (ret > 0) {
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str = lock_user(VERIFY_READ, tstr, ret, true);
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ret = str ? 0 : -EFAULT;
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}
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*pstr = str;
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return ret;
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}
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/*
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* GDB semihosting syscall implementations.
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*/
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static gdb_syscall_complete_cb gdb_open_complete;
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static void gdb_open_cb(CPUState *cs, target_ulong ret, target_ulong err)
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{
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if (!err) {
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int guestfd = alloc_guestfd();
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associate_guestfd(guestfd, ret);
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ret = guestfd;
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}
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gdb_open_complete(cs, ret, err);
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}
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static void gdb_open(CPUState *cs, gdb_syscall_complete_cb complete,
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target_ulong fname, target_ulong fname_len,
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int gdb_flags, int mode)
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{
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int len = validate_strlen(cs, fname, fname_len);
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if (len < 0) {
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complete(cs, -1, -len);
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return;
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}
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gdb_open_complete = complete;
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gdb_do_syscall(gdb_open_cb, "open,%s,%x,%x",
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fname, len, (target_ulong)gdb_flags, (target_ulong)mode);
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}
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/*
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* Host semihosting syscall implementations.
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*/
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static void host_open(CPUState *cs, gdb_syscall_complete_cb complete,
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target_ulong fname, target_ulong fname_len,
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int gdb_flags, int mode)
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{
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CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
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char *p;
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int ret, host_flags;
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ret = validate_lock_user_string(&p, cs, fname, fname_len);
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if (ret < 0) {
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complete(cs, -1, -ret);
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return;
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}
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if (gdb_flags & GDB_O_WRONLY) {
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host_flags = O_WRONLY;
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} else if (gdb_flags & GDB_O_RDWR) {
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host_flags = O_RDWR;
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} else {
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host_flags = O_RDONLY;
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}
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if (gdb_flags & GDB_O_CREAT) {
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host_flags |= O_CREAT;
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}
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if (gdb_flags & GDB_O_TRUNC) {
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host_flags |= O_TRUNC;
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}
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if (gdb_flags & GDB_O_EXCL) {
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host_flags |= O_EXCL;
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}
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ret = open(p, host_flags, mode);
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if (ret < 0) {
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complete(cs, -1, errno);
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} else {
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int guestfd = alloc_guestfd();
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associate_guestfd(guestfd, ret);
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complete(cs, guestfd, 0);
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}
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unlock_user(p, fname, 0);
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}
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/*
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* Syscall entry points.
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*/
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void semihost_sys_open(CPUState *cs, gdb_syscall_complete_cb complete,
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target_ulong fname, target_ulong fname_len,
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int gdb_flags, int mode)
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{
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if (use_gdb_syscalls()) {
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gdb_open(cs, complete, fname, fname_len, gdb_flags, mode);
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} else {
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host_open(cs, complete, fname, fname_len, gdb_flags, mode);
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}
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}
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