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/*
* Syscall implementations for semihosting.
*
* Copyright (c) 2022 Linaro
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "qemu/osdep.h"
#include "exec/gdbstub.h"
#include "semihosting/guestfd.h"
#include "semihosting/syscalls.h"
#ifdef CONFIG_USER_ONLY
#include "qemu.h"
#else
#include "semihosting/softmmu-uaccess.h"
#endif
/*
* Validate or compute the length of the string (including terminator).
*/
static int validate_strlen(CPUState *cs, target_ulong str, target_ulong tlen)
{
CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
char c;
if (tlen == 0) {
ssize_t slen = target_strlen(str);
if (slen < 0) {
return -EFAULT;
}
if (slen >= INT32_MAX) {
return -ENAMETOOLONG;
}
return slen + 1;
}
if (tlen > INT32_MAX) {
return -ENAMETOOLONG;
}
if (get_user_u8(c, str + tlen - 1)) {
return -EFAULT;
}
if (c != 0) {
return -EINVAL;
}
return tlen;
}
static int validate_lock_user_string(char **pstr, CPUState *cs,
target_ulong tstr, target_ulong tlen)
{
int ret = validate_strlen(cs, tstr, tlen);
CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
char *str = NULL;
if (ret > 0) {
str = lock_user(VERIFY_READ, tstr, ret, true);
ret = str ? 0 : -EFAULT;
}
*pstr = str;
return ret;
}
/*
* GDB semihosting syscall implementations.
*/
static gdb_syscall_complete_cb gdb_open_complete;
static void gdb_open_cb(CPUState *cs, target_ulong ret, target_ulong err)
{
if (!err) {
int guestfd = alloc_guestfd();
associate_guestfd(guestfd, ret);
ret = guestfd;
}
gdb_open_complete(cs, ret, err);
}
static void gdb_open(CPUState *cs, gdb_syscall_complete_cb complete,
target_ulong fname, target_ulong fname_len,
int gdb_flags, int mode)
{
int len = validate_strlen(cs, fname, fname_len);
if (len < 0) {
complete(cs, -1, -len);
return;
}
gdb_open_complete = complete;
gdb_do_syscall(gdb_open_cb, "open,%s,%x,%x",
fname, len, (target_ulong)gdb_flags, (target_ulong)mode);
}
static void gdb_close(CPUState *cs, gdb_syscall_complete_cb complete,
GuestFD *gf)
{
gdb_do_syscall(complete, "close,%x", (target_ulong)gf->hostfd);
}
/*
* Host semihosting syscall implementations.
*/
static void host_open(CPUState *cs, gdb_syscall_complete_cb complete,
target_ulong fname, target_ulong fname_len,
int gdb_flags, int mode)
{
CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
char *p;
int ret, host_flags;
ret = validate_lock_user_string(&p, cs, fname, fname_len);
if (ret < 0) {
complete(cs, -1, -ret);
return;
}
if (gdb_flags & GDB_O_WRONLY) {
host_flags = O_WRONLY;
} else if (gdb_flags & GDB_O_RDWR) {
host_flags = O_RDWR;
} else {
host_flags = O_RDONLY;
}
if (gdb_flags & GDB_O_CREAT) {
host_flags |= O_CREAT;
}
if (gdb_flags & GDB_O_TRUNC) {
host_flags |= O_TRUNC;
}
if (gdb_flags & GDB_O_EXCL) {
host_flags |= O_EXCL;
}
ret = open(p, host_flags, mode);
if (ret < 0) {
complete(cs, -1, errno);
} else {
int guestfd = alloc_guestfd();
associate_guestfd(guestfd, ret);
complete(cs, guestfd, 0);
}
unlock_user(p, fname, 0);
}
static void host_close(CPUState *cs, gdb_syscall_complete_cb complete,
GuestFD *gf)
{
/*
* Only close the underlying host fd if it's one we opened on behalf
* of the guest in SYS_OPEN.
*/
if (gf->hostfd != STDIN_FILENO &&
gf->hostfd != STDOUT_FILENO &&
gf->hostfd != STDERR_FILENO &&
close(gf->hostfd) < 0) {
complete(cs, -1, errno);
} else {
complete(cs, 0, 0);
}
}
/*
* Syscall entry points.
*/
void semihost_sys_open(CPUState *cs, gdb_syscall_complete_cb complete,
target_ulong fname, target_ulong fname_len,
int gdb_flags, int mode)
{
if (use_gdb_syscalls()) {
gdb_open(cs, complete, fname, fname_len, gdb_flags, mode);
} else {
host_open(cs, complete, fname, fname_len, gdb_flags, mode);
}
}
void semihost_sys_close(CPUState *cs, gdb_syscall_complete_cb complete, int fd)
{
GuestFD *gf = get_guestfd(fd);
if (!gf) {
complete(cs, -1, EBADF);
return;
}
switch (gf->type) {
case GuestFDGDB:
gdb_close(cs, complete, gf);
break;
case GuestFDHost:
host_close(cs, complete, gf);
break;
case GuestFDStatic:
complete(cs, 0, 0);
break;
default:
g_assert_not_reached();
}
dealloc_guestfd(fd);
}
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