40f1219a8b
Fixes a minor bug in which a 64-bit guest on a 32-bit host could truncate the length. This would only ever cause a problem if there were no bits set in the low 32, so that it truncates to 0. Reviewed-by: Luc Michel <lmichel@kalray.eu> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
359 lines
9.1 KiB
C
359 lines
9.1 KiB
C
/*
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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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static void gdb_close(CPUState *cs, gdb_syscall_complete_cb complete,
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GuestFD *gf)
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{
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gdb_do_syscall(complete, "close,%x", (target_ulong)gf->hostfd);
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}
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static void gdb_read(CPUState *cs, gdb_syscall_complete_cb complete,
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GuestFD *gf, target_ulong buf, target_ulong len)
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{
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gdb_do_syscall(complete, "read,%x,%x,%x",
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(target_ulong)gf->hostfd, buf, len);
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}
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static void gdb_write(CPUState *cs, gdb_syscall_complete_cb complete,
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GuestFD *gf, target_ulong buf, target_ulong len)
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{
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gdb_do_syscall(complete, "write,%x,%x,%x",
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(target_ulong)gf->hostfd, buf, len);
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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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static void host_close(CPUState *cs, gdb_syscall_complete_cb complete,
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GuestFD *gf)
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{
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/*
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* Only close the underlying host fd if it's one we opened on behalf
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* of the guest in SYS_OPEN.
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*/
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if (gf->hostfd != STDIN_FILENO &&
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gf->hostfd != STDOUT_FILENO &&
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gf->hostfd != STDERR_FILENO &&
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close(gf->hostfd) < 0) {
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complete(cs, -1, errno);
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} else {
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complete(cs, 0, 0);
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}
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}
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static void host_read(CPUState *cs, gdb_syscall_complete_cb complete,
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GuestFD *gf, target_ulong buf, target_ulong len)
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{
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CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
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void *ptr = lock_user(VERIFY_WRITE, buf, len, 0);
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ssize_t ret;
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if (!ptr) {
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complete(cs, -1, EFAULT);
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return;
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}
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do {
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ret = read(gf->hostfd, ptr, len);
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} while (ret == -1 && errno == EINTR);
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if (ret == -1) {
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complete(cs, -1, errno);
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unlock_user(ptr, buf, 0);
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} else {
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complete(cs, ret, 0);
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unlock_user(ptr, buf, ret);
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}
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}
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static void host_write(CPUState *cs, gdb_syscall_complete_cb complete,
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GuestFD *gf, target_ulong buf, target_ulong len)
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{
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CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
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void *ptr = lock_user(VERIFY_READ, buf, len, 1);
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ssize_t ret;
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if (!ptr) {
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complete(cs, -1, EFAULT);
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return;
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}
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ret = write(gf->hostfd, ptr, len);
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complete(cs, ret, ret == -1 ? errno : 0);
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unlock_user(ptr, buf, 0);
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}
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/*
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* Static file semihosting syscall implementations.
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*/
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static void staticfile_read(CPUState *cs, gdb_syscall_complete_cb complete,
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GuestFD *gf, target_ulong buf, target_ulong len)
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{
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CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
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target_ulong rest = gf->staticfile.len - gf->staticfile.off;
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void *ptr;
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if (len > rest) {
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len = rest;
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}
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ptr = lock_user(VERIFY_WRITE, buf, len, 0);
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if (!ptr) {
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complete(cs, -1, EFAULT);
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return;
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}
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memcpy(ptr, gf->staticfile.data + gf->staticfile.off, len);
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gf->staticfile.off += len;
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complete(cs, len, 0);
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unlock_user(ptr, buf, len);
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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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void semihost_sys_close(CPUState *cs, gdb_syscall_complete_cb complete, int fd)
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{
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GuestFD *gf = get_guestfd(fd);
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if (!gf) {
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complete(cs, -1, EBADF);
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return;
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}
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switch (gf->type) {
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case GuestFDGDB:
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gdb_close(cs, complete, gf);
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break;
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case GuestFDHost:
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host_close(cs, complete, gf);
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break;
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case GuestFDStatic:
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complete(cs, 0, 0);
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break;
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default:
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g_assert_not_reached();
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}
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dealloc_guestfd(fd);
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}
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void semihost_sys_read_gf(CPUState *cs, gdb_syscall_complete_cb complete,
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GuestFD *gf, target_ulong buf, target_ulong len)
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{
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/*
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* Bound length for 64-bit guests on 32-bit hosts, not overlowing ssize_t.
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* Note the Linux kernel does this with MAX_RW_COUNT, so it's not a bad
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* idea to do this unconditionally.
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*/
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if (len > INT32_MAX) {
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len = INT32_MAX;
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}
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switch (gf->type) {
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case GuestFDGDB:
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gdb_read(cs, complete, gf, buf, len);
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break;
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case GuestFDHost:
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host_read(cs, complete, gf, buf, len);
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break;
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case GuestFDStatic:
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staticfile_read(cs, complete, gf, buf, len);
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break;
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default:
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g_assert_not_reached();
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}
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}
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void semihost_sys_read(CPUState *cs, gdb_syscall_complete_cb complete,
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int fd, target_ulong buf, target_ulong len)
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{
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GuestFD *gf = get_guestfd(fd);
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if (gf) {
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semihost_sys_read_gf(cs, complete, gf, buf, len);
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} else {
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complete(cs, -1, EBADF);
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}
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}
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void semihost_sys_write_gf(CPUState *cs, gdb_syscall_complete_cb complete,
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GuestFD *gf, target_ulong buf, target_ulong len)
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{
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/*
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* Bound length for 64-bit guests on 32-bit hosts, not overlowing ssize_t.
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* Note the Linux kernel does this with MAX_RW_COUNT, so it's not a bad
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* idea to do this unconditionally.
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*/
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if (len > INT32_MAX) {
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len = INT32_MAX;
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}
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switch (gf->type) {
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case GuestFDGDB:
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gdb_write(cs, complete, gf, buf, len);
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break;
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case GuestFDHost:
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host_write(cs, complete, gf, buf, len);
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break;
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case GuestFDStatic:
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/* Static files are never open for writing: EBADF. */
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complete(cs, -1, EBADF);
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break;
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default:
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g_assert_not_reached();
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}
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}
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void semihost_sys_write(CPUState *cs, gdb_syscall_complete_cb complete,
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int fd, target_ulong buf, target_ulong len)
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{
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GuestFD *gf = get_guestfd(fd);
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if (gf) {
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semihost_sys_write_gf(cs, complete, gf, buf, len);
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} else {
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complete(cs, -1, EBADF);
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}
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}
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