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qemu/semihosting/arm-compat-semi.c
Alex Bennée 424d5ecf52 semihosting: update link to spec 
The old link has moved but it seems the document is now hosted on
Arm's github along with a license update to CC-BY-SA-4.0.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220929114231.583801-42-alex.bennee@linaro.org>
2022-10-06 11:53:41 +01:00

795 lines
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/*
* Semihosting support for systems modeled on the Arm "Angel"
* semihosting syscalls design. This includes Arm and RISC-V processors
*
* Copyright (c) 2005, 2007 CodeSourcery.
* Copyright (c) 2019 Linaro
* Written by Paul Brook.
*
* Copyright © 2020 by Keith Packard <keithp@keithp.com>
* Adapted for systems other than ARM, including RISC-V, by Keith Packard
*
* 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/>.
*
* ARM Semihosting is documented in:
* Semihosting for AArch32 and AArch64 Release 2.0
* https://github.com/ARM-software/abi-aa/blob/main/semihosting/semihosting.rst
*
* 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"
#include "qemu/timer.h"
#include "exec/gdbstub.h"
#include "semihosting/semihost.h"
#include "semihosting/console.h"
#include "semihosting/common-semi.h"
#include "semihosting/guestfd.h"
#include "semihosting/syscalls.h"
#ifdef CONFIG_USER_ONLY
#include "qemu.h"
#define COMMON_SEMI_HEAP_SIZE (128 * 1024 * 1024)
#else
#include "qemu/cutils.h"
#include "hw/loader.h"
#include "hw/boards.h"
#endif
#define TARGET_SYS_OPEN 0x01
#define TARGET_SYS_CLOSE 0x02
#define TARGET_SYS_WRITEC 0x03
#define TARGET_SYS_WRITE0 0x04
#define TARGET_SYS_WRITE 0x05
#define TARGET_SYS_READ 0x06
#define TARGET_SYS_READC 0x07
#define TARGET_SYS_ISERROR 0x08
#define TARGET_SYS_ISTTY 0x09
#define TARGET_SYS_SEEK 0x0a
#define TARGET_SYS_FLEN 0x0c
#define TARGET_SYS_TMPNAM 0x0d
#define TARGET_SYS_REMOVE 0x0e
#define TARGET_SYS_RENAME 0x0f
#define TARGET_SYS_CLOCK 0x10
#define TARGET_SYS_TIME 0x11
#define TARGET_SYS_SYSTEM 0x12
#define TARGET_SYS_ERRNO 0x13
#define TARGET_SYS_GET_CMDLINE 0x15
#define TARGET_SYS_HEAPINFO 0x16
#define TARGET_SYS_EXIT 0x18
#define TARGET_SYS_SYNCCACHE 0x19
#define TARGET_SYS_EXIT_EXTENDED 0x20
#define TARGET_SYS_ELAPSED 0x30
#define TARGET_SYS_TICKFREQ 0x31
/* ADP_Stopped_ApplicationExit is used for exit(0),
* anything else is implemented as exit(1) */
#define ADP_Stopped_ApplicationExit (0x20026)
#ifndef O_BINARY
#define O_BINARY 0
#endif
static int gdb_open_modeflags[12] = {
GDB_O_RDONLY,
GDB_O_RDONLY,
GDB_O_RDWR,
GDB_O_RDWR,
GDB_O_WRONLY | GDB_O_CREAT | GDB_O_TRUNC,
GDB_O_WRONLY | GDB_O_CREAT | GDB_O_TRUNC,
GDB_O_RDWR | GDB_O_CREAT | GDB_O_TRUNC,
GDB_O_RDWR | GDB_O_CREAT | GDB_O_TRUNC,
GDB_O_WRONLY | GDB_O_CREAT | GDB_O_APPEND,
GDB_O_WRONLY | GDB_O_CREAT | GDB_O_APPEND,
GDB_O_RDWR | GDB_O_CREAT | GDB_O_APPEND,
GDB_O_RDWR | GDB_O_CREAT | GDB_O_APPEND,
};
#ifndef CONFIG_USER_ONLY
/**
* common_semi_find_bases: find information about ram and heap base
*
* This function attempts to provide meaningful numbers for RAM and
* HEAP base addresses. The rambase is simply the lowest addressable
* RAM position. For the heapbase we ask the loader to scan the
* address space and the largest available gap by querying the "ROM"
* regions.
*
* Returns: a structure with the numbers we need.
*/
typedef struct LayoutInfo {
target_ulong rambase;
size_t ramsize;
hwaddr heapbase;
hwaddr heaplimit;
} LayoutInfo;
static bool find_ram_cb(Int128 start, Int128 len, const MemoryRegion *mr,
hwaddr offset_in_region, void *opaque)
{
LayoutInfo *info = (LayoutInfo *) opaque;
uint64_t size = int128_get64(len);
if (!mr->ram || mr->readonly) {
return false;
}
if (size > info->ramsize) {
info->rambase = int128_get64(start);
info->ramsize = size;
}
/* search exhaustively for largest RAM */
return false;
}
static LayoutInfo common_semi_find_bases(CPUState *cs)
{
FlatView *fv;
LayoutInfo info = { 0, 0, 0, 0 };
RCU_READ_LOCK_GUARD();
fv = address_space_to_flatview(cs->as);
flatview_for_each_range(fv, find_ram_cb, &info);
/*
* If we have found the RAM lets iterate through the ROM blobs to
* work out the best place for the remainder of RAM and split it
* equally between stack and heap.
*/
if (info.rambase || info.ramsize > 0) {
RomGap gap = rom_find_largest_gap_between(info.rambase, info.ramsize);
info.heapbase = gap.base;
info.heaplimit = gap.base + gap.size;
}
return info;
}
#endif
#include "common-semi-target.h"
/*
* Read the input value from the argument block; fail the semihosting
* call if the memory read fails. Eventually we could use a generic
* CPUState helper function here.
* Note that GET_ARG() handles memory access errors by jumping to
* do_fault, so must be used as the first thing done in handling a
* semihosting call, to avoid accidentally leaking allocated resources.
* SET_ARG(), since it unavoidably happens late, instead returns an
* error indication (0 on success, non-0 for error) which the caller
* should check.
*/
#define GET_ARG(n) do { \
if (is_64bit_semihosting(env)) { \
if (get_user_u64(arg ## n, args + (n) * 8)) { \
goto do_fault; \
} \
} else { \
if (get_user_u32(arg ## n, args + (n) * 4)) { \
goto do_fault; \
} \
} \
} while (0)
#define SET_ARG(n, val) \
(is_64bit_semihosting(env) ? \
put_user_u64(val, args + (n) * 8) : \
put_user_u32(val, args + (n) * 4))
/*
* The semihosting API has no concept of its errno being thread-safe,
* as the API design predates SMP CPUs and was intended as a simple
* real-hardware set of debug functionality. For QEMU, we make the
* errno be per-thread in linux-user mode; in softmmu it is a simple
* global, and we assume that the guest takes care of avoiding any races.
*/
#ifndef CONFIG_USER_ONLY
static target_ulong syscall_err;
#include "semihosting/softmmu-uaccess.h"
#endif
static inline uint32_t get_swi_errno(CPUState *cs)
{
#ifdef CONFIG_USER_ONLY
TaskState *ts = cs->opaque;
return ts->swi_errno;
#else
return syscall_err;
#endif
}
static void common_semi_cb(CPUState *cs, uint64_t ret, int err)
{
if (err) {
#ifdef CONFIG_USER_ONLY
TaskState *ts = cs->opaque;
ts->swi_errno = err;
#else
syscall_err = err;
#endif
}
common_semi_set_ret(cs, ret);
}
/*
* Use 0xdeadbeef as the return value when there isn't a defined
* return value for the call.
*/
static void common_semi_dead_cb(CPUState *cs, uint64_t ret, int err)
{
common_semi_set_ret(cs, 0xdeadbeef);
}
/*
* SYS_READ and SYS_WRITE always return the number of bytes not read/written.
* There is no error condition, other than returning the original length.
*/
static void common_semi_rw_cb(CPUState *cs, uint64_t ret, int err)
{
/* Recover the original length from the third argument. */
CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
target_ulong args = common_semi_arg(cs, 1);
target_ulong arg2;
GET_ARG(2);
if (err) {
do_fault:
ret = 0; /* error: no bytes transmitted */
}
common_semi_set_ret(cs, arg2 - ret);
}
/*
* Convert from Posix ret+errno to Arm SYS_ISTTY return values.
* With gdbstub, err is only ever set for protocol errors to EIO.
*/
static void common_semi_istty_cb(CPUState *cs, uint64_t ret, int err)
{
if (err) {
ret = (err == ENOTTY ? 0 : -1);
}
common_semi_cb(cs, ret, err);
}
/*
* SYS_SEEK returns 0 on success, not the resulting offset.
*/
static void common_semi_seek_cb(CPUState *cs, uint64_t ret, int err)
{
if (!err) {
ret = 0;
}
common_semi_cb(cs, ret, err);
}
/*
* Return an address in target memory of 64 bytes where the remote
* gdb should write its stat struct. (The format of this structure
* is defined by GDB's remote protocol and is not target-specific.)
* We put this on the guest's stack just below SP.
*/
static target_ulong common_semi_flen_buf(CPUState *cs)
{
target_ulong sp = common_semi_stack_bottom(cs);
return sp - 64;
}
static void
common_semi_flen_fstat_cb(CPUState *cs, uint64_t ret, int err)
{
if (!err) {
/* The size is always stored in big-endian order, extract the value. */
uint64_t size;
if (cpu_memory_rw_debug(cs, common_semi_flen_buf(cs) +
offsetof(struct gdb_stat, gdb_st_size),
&size, 8, 0)) {
ret = -1, err = EFAULT;
} else {
size = be64_to_cpu(size);
if (ret != size) {
ret = -1, err = EOVERFLOW;
}
}
}
common_semi_cb(cs, ret, err);
}
static void
common_semi_readc_cb(CPUState *cs, uint64_t ret, int err)
{
if (!err) {
CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
uint8_t ch;
if (get_user_u8(ch, common_semi_stack_bottom(cs) - 1)) {
ret = -1, err = EFAULT;
} else {
ret = ch;
}
}
common_semi_cb(cs, ret, err);
}
#define SHFB_MAGIC_0 0x53
#define SHFB_MAGIC_1 0x48
#define SHFB_MAGIC_2 0x46
#define SHFB_MAGIC_3 0x42
/* Feature bits reportable in feature byte 0 */
#define SH_EXT_EXIT_EXTENDED (1 << 0)
#define SH_EXT_STDOUT_STDERR (1 << 1)
static const uint8_t featurefile_data[] = {
SHFB_MAGIC_0,
SHFB_MAGIC_1,
SHFB_MAGIC_2,
SHFB_MAGIC_3,
SH_EXT_EXIT_EXTENDED | SH_EXT_STDOUT_STDERR, /* Feature byte 0 */
};
/*
* Do a semihosting call.
*
* The specification always says that the "return register" either
* returns a specific value or is corrupted, so we don't need to
* report to our caller whether we are returning a value or trying to
* leave the register unchanged.
*/
void do_common_semihosting(CPUState *cs)
{
CPUArchState *env = cs->env_ptr;
target_ulong args;
target_ulong arg0, arg1, arg2, arg3;
target_ulong ul_ret;
char * s;
int nr;
uint32_t ret;
int64_t elapsed;
nr = common_semi_arg(cs, 0) & 0xffffffffU;
args = common_semi_arg(cs, 1);
switch (nr) {
case TARGET_SYS_OPEN:
{
int ret, err = 0;
int hostfd;
GET_ARG(0);
GET_ARG(1);
GET_ARG(2);
s = lock_user_string(arg0);
if (!s) {
goto do_fault;
}
if (arg1 >= 12) {
unlock_user(s, arg0, 0);
common_semi_cb(cs, -1, EINVAL);
break;
}
if (strcmp(s, ":tt") == 0) {
/*
* We implement SH_EXT_STDOUT_STDERR, so:
* open for read == stdin
* open for write == stdout
* open for append == stderr
*/
if (arg1 < 4) {
hostfd = STDIN_FILENO;
} else if (arg1 < 8) {
hostfd = STDOUT_FILENO;
} else {
hostfd = STDERR_FILENO;
}
ret = alloc_guestfd();
associate_guestfd(ret, hostfd);
} else if (strcmp(s, ":semihosting-features") == 0) {
/* We must fail opens for modes other than 0 ('r') or 1 ('rb') */
if (arg1 != 0 && arg1 != 1) {
ret = -1;
err = EACCES;
} else {
ret = alloc_guestfd();
staticfile_guestfd(ret, featurefile_data,
sizeof(featurefile_data));
}
} else {
unlock_user(s, arg0, 0);
semihost_sys_open(cs, common_semi_cb, arg0, arg2 + 1,
gdb_open_modeflags[arg1], 0644);
break;
}
unlock_user(s, arg0, 0);
common_semi_cb(cs, ret, err);
break;
}
case TARGET_SYS_CLOSE:
GET_ARG(0);
semihost_sys_close(cs, common_semi_cb, arg0);
break;
case TARGET_SYS_WRITEC:
/*
* FIXME: the byte to be written is in a target_ulong slot,
* which means this is wrong for a big-endian guest.
*/
semihost_sys_write_gf(cs, common_semi_dead_cb,
&console_out_gf, args, 1);
break;
case TARGET_SYS_WRITE0:
{
ssize_t len = target_strlen(args);
if (len < 0) {
common_semi_dead_cb(cs, -1, EFAULT);
} else {
semihost_sys_write_gf(cs, common_semi_dead_cb,
&console_out_gf, args, len);
}
}
break;
case TARGET_SYS_WRITE:
GET_ARG(0);
GET_ARG(1);
GET_ARG(2);
semihost_sys_write(cs, common_semi_rw_cb, arg0, arg1, arg2);
break;
case TARGET_SYS_READ:
GET_ARG(0);
GET_ARG(1);
GET_ARG(2);
semihost_sys_read(cs, common_semi_rw_cb, arg0, arg1, arg2);
break;
case TARGET_SYS_READC:
semihost_sys_read_gf(cs, common_semi_readc_cb, &console_in_gf,
common_semi_stack_bottom(cs) - 1, 1);
break;
case TARGET_SYS_ISERROR:
GET_ARG(0);
common_semi_set_ret(cs, (target_long)arg0 < 0);
break;
case TARGET_SYS_ISTTY:
GET_ARG(0);
semihost_sys_isatty(cs, common_semi_istty_cb, arg0);
break;
case TARGET_SYS_SEEK:
GET_ARG(0);
GET_ARG(1);
semihost_sys_lseek(cs, common_semi_seek_cb, arg0, arg1, GDB_SEEK_SET);
break;
case TARGET_SYS_FLEN:
GET_ARG(0);
semihost_sys_flen(cs, common_semi_flen_fstat_cb, common_semi_cb,
arg0, common_semi_flen_buf(cs));
break;
case TARGET_SYS_TMPNAM:
{
int len;
char *p;
GET_ARG(0);
GET_ARG(1);
GET_ARG(2);
len = asprintf(&s, "/tmp/qemu-%x%02x", getpid(), (int)arg1 & 0xff);
if (len < 0) {
common_semi_set_ret(cs, -1);
break;
}
/* Allow for trailing NUL */
len++;
/* Make sure there's enough space in the buffer */
if (len > arg2) {
free(s);
common_semi_set_ret(cs, -1);
break;
}
p = lock_user(VERIFY_WRITE, arg0, len, 0);
if (!p) {
free(s);
goto do_fault;
}
memcpy(p, s, len);
unlock_user(p, arg0, len);
free(s);
common_semi_set_ret(cs, 0);
break;
}
case TARGET_SYS_REMOVE:
GET_ARG(0);
GET_ARG(1);
semihost_sys_remove(cs, common_semi_cb, arg0, arg1 + 1);
break;
case TARGET_SYS_RENAME:
GET_ARG(0);
GET_ARG(1);
GET_ARG(2);
GET_ARG(3);
semihost_sys_rename(cs, common_semi_cb, arg0, arg1 + 1, arg2, arg3 + 1);
break;
case TARGET_SYS_CLOCK:
common_semi_set_ret(cs, clock() / (CLOCKS_PER_SEC / 100));
break;
case TARGET_SYS_TIME:
ul_ret = time(NULL);
common_semi_cb(cs, ul_ret, ul_ret == -1 ? errno : 0);
break;
case TARGET_SYS_SYSTEM:
GET_ARG(0);
GET_ARG(1);
semihost_sys_system(cs, common_semi_cb, arg0, arg1 + 1);
break;
case TARGET_SYS_ERRNO:
common_semi_set_ret(cs, get_swi_errno(cs));
break;
case TARGET_SYS_GET_CMDLINE:
{
/* Build a command-line from the original argv.
*
* The inputs are:
* * arg0, pointer to a buffer of at least the size
* specified in arg1.
* * arg1, size of the buffer pointed to by arg0 in
* bytes.
*
* The outputs are:
* * arg0, pointer to null-terminated string of the
* command line.
* * arg1, length of the string pointed to by arg0.
*/
char *output_buffer;
size_t input_size;
size_t output_size;
int status = 0;
#if !defined(CONFIG_USER_ONLY)
const char *cmdline;
#else
TaskState *ts = cs->opaque;
#endif
GET_ARG(0);
GET_ARG(1);
input_size = arg1;
/* Compute the size of the output string. */
#if !defined(CONFIG_USER_ONLY)
cmdline = semihosting_get_cmdline();
if (cmdline == NULL) {
cmdline = ""; /* Default to an empty line. */
}
output_size = strlen(cmdline) + 1; /* Count terminating 0. */
#else
unsigned int i;
output_size = ts->info->env_strings - ts->info->arg_strings;
if (!output_size) {
/*
* We special-case the "empty command line" case (argc==0).
* Just provide the terminating 0.
*/
output_size = 1;
}
#endif
if (output_size > input_size) {
/* Not enough space to store command-line arguments. */
common_semi_cb(cs, -1, E2BIG);
break;
}
/* Adjust the command-line length. */
if (SET_ARG(1, output_size - 1)) {
/* Couldn't write back to argument block */
goto do_fault;
}
/* Lock the buffer on the ARM side. */
output_buffer = lock_user(VERIFY_WRITE, arg0, output_size, 0);
if (!output_buffer) {
goto do_fault;
}
/* Copy the command-line arguments. */
#if !defined(CONFIG_USER_ONLY)
pstrcpy(output_buffer, output_size, cmdline);
#else
if (output_size == 1) {
/* Empty command-line. */
output_buffer[0] = '\0';
goto out;
}
if (copy_from_user(output_buffer, ts->info->arg_strings,
output_size)) {
unlock_user(output_buffer, arg0, 0);
goto do_fault;
}
/* Separate arguments by white spaces. */
for (i = 0; i < output_size - 1; i++) {
if (output_buffer[i] == 0) {
output_buffer[i] = ' ';
}
}
out:
#endif
/* Unlock the buffer on the ARM side. */
unlock_user(output_buffer, arg0, output_size);
common_semi_cb(cs, status, 0);
}
break;
case TARGET_SYS_HEAPINFO:
{
target_ulong retvals[4];
int i;
#ifdef CONFIG_USER_ONLY
TaskState *ts = cs->opaque;
target_ulong limit;
#else
LayoutInfo info = common_semi_find_bases(cs);
#endif
GET_ARG(0);
#ifdef CONFIG_USER_ONLY
/*
* Some C libraries assume the heap immediately follows .bss, so
* allocate it using sbrk.
*/
if (!ts->heap_limit) {
abi_ulong ret;
ts->heap_base = do_brk(0);
limit = ts->heap_base + COMMON_SEMI_HEAP_SIZE;
/* Try a big heap, and reduce the size if that fails. */
for (;;) {
ret = do_brk(limit);
if (ret >= limit) {
break;
}
limit = (ts->heap_base >> 1) + (limit >> 1);
}
ts->heap_limit = limit;
}
retvals[0] = ts->heap_base;
retvals[1] = ts->heap_limit;
retvals[2] = ts->stack_base;
retvals[3] = 0; /* Stack limit. */
#else
retvals[0] = info.heapbase; /* Heap Base */
retvals[1] = info.heaplimit; /* Heap Limit */
retvals[2] = info.heaplimit; /* Stack base */
retvals[3] = info.heapbase; /* Stack limit. */
#endif
for (i = 0; i < ARRAY_SIZE(retvals); i++) {
bool fail;
if (is_64bit_semihosting(env)) {
fail = put_user_u64(retvals[i], arg0 + i * 8);
} else {
fail = put_user_u32(retvals[i], arg0 + i * 4);
}
if (fail) {
/* Couldn't write back to argument block */
goto do_fault;
}
}
common_semi_set_ret(cs, 0);
}
break;
case TARGET_SYS_EXIT:
case TARGET_SYS_EXIT_EXTENDED:
if (common_semi_sys_exit_extended(cs, nr)) {
/*
* The A64 version of SYS_EXIT takes a parameter block,
* so the application-exit type can return a subcode which
* is the exit status code from the application.
* SYS_EXIT_EXTENDED is an a new-in-v2.0 optional function
* which allows A32/T32 guests to also provide a status code.
*/
GET_ARG(0);
GET_ARG(1);
if (arg0 == ADP_Stopped_ApplicationExit) {
ret = arg1;
} else {
ret = 1;
}
} else {
/*
* The A32/T32 version of SYS_EXIT specifies only
* Stopped_ApplicationExit as normal exit, but does not
* allow the guest to specify the exit status code.
* Everything else is considered an error.
*/
ret = (args == ADP_Stopped_ApplicationExit) ? 0 : 1;
}
gdb_exit(ret);
exit(ret);
case TARGET_SYS_ELAPSED:
elapsed = get_clock() - clock_start;
if (sizeof(target_ulong) == 8) {
if (SET_ARG(0, elapsed)) {
goto do_fault;
}
} else {
if (SET_ARG(0, (uint32_t) elapsed) ||
SET_ARG(1, (uint32_t) (elapsed >> 32))) {
goto do_fault;
}
}
common_semi_set_ret(cs, 0);
break;
case TARGET_SYS_TICKFREQ:
/* qemu always uses nsec */
common_semi_set_ret(cs, 1000000000);
break;
case TARGET_SYS_SYNCCACHE:
/*
* Clean the D-cache and invalidate the I-cache for the specified
* virtual address range. This is a nop for us since we don't
* implement caches. This is only present on A64.
*/
if (common_semi_has_synccache(env)) {
common_semi_set_ret(cs, 0);
break;
}
/* fall through */
default:
fprintf(stderr, "qemu: Unsupported SemiHosting SWI 0x%02x\n", nr);
cpu_dump_state(cs, stderr, 0);
abort();
do_fault:
common_semi_cb(cs, -1, EFAULT);
break;
}
}
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