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4cb28db99b
qemu/target/arm/arm-semi.c
Alex Bennée 4cb28db99b target/arm: fixup some of the commentary for arm-semi 
This cleans up a number of the block comments to fit the proper style.
While we are at it we also reference the official specification and
document what the return register value can be.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
2019-05-28 10:28:50 +01:00

678 lines
21 KiB
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/*
* Arm "Angel" semihosting syscalls
*
* Copyright (c) 2005, 2007 CodeSourcery.
* Copyright (c) 2019 Linaro
* Written by Paul Brook.
*
* 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://static.docs.arm.com/100863/0200/semihosting.pdf
*/
#include "qemu/osdep.h"
#include "cpu.h"
#include "hw/semihosting/semihost.h"
#ifdef CONFIG_USER_ONLY
#include "qemu.h"
#define ARM_ANGEL_HEAP_SIZE (128 * 1024 * 1024)
#else
#include "qemu-common.h"
#include "exec/gdbstub.h"
#include "qemu/cutils.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_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
/* 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
#define GDB_O_RDONLY 0x000
#define GDB_O_WRONLY 0x001
#define GDB_O_RDWR 0x002
#define GDB_O_APPEND 0x008
#define GDB_O_CREAT 0x200
#define GDB_O_TRUNC 0x400
#define GDB_O_BINARY 0
static int gdb_open_modeflags[12] = {
GDB_O_RDONLY,
GDB_O_RDONLY | GDB_O_BINARY,
GDB_O_RDWR,
GDB_O_RDWR | GDB_O_BINARY,
GDB_O_WRONLY | GDB_O_CREAT | GDB_O_TRUNC,
GDB_O_WRONLY | GDB_O_CREAT | GDB_O_TRUNC | GDB_O_BINARY,
GDB_O_RDWR | GDB_O_CREAT | GDB_O_TRUNC,
GDB_O_RDWR | GDB_O_CREAT | GDB_O_TRUNC | GDB_O_BINARY,
GDB_O_WRONLY | GDB_O_CREAT | GDB_O_APPEND,
GDB_O_WRONLY | GDB_O_CREAT | GDB_O_APPEND | GDB_O_BINARY,
GDB_O_RDWR | GDB_O_CREAT | GDB_O_APPEND,
GDB_O_RDWR | GDB_O_CREAT | GDB_O_APPEND | GDB_O_BINARY
};
static int open_modeflags[12] = {
O_RDONLY,
O_RDONLY | O_BINARY,
O_RDWR,
O_RDWR | O_BINARY,
O_WRONLY | O_CREAT | O_TRUNC,
O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
O_RDWR | O_CREAT | O_TRUNC,
O_RDWR | O_CREAT | O_TRUNC | O_BINARY,
O_WRONLY | O_CREAT | O_APPEND,
O_WRONLY | O_CREAT | O_APPEND | O_BINARY,
O_RDWR | O_CREAT | O_APPEND,
O_RDWR | O_CREAT | O_APPEND | O_BINARY
};
#ifdef CONFIG_USER_ONLY
static inline uint32_t set_swi_errno(TaskState *ts, uint32_t code)
{
if (code == (uint32_t)-1)
ts->swi_errno = errno;
return code;
}
#else
static inline uint32_t set_swi_errno(CPUARMState *env, uint32_t code)
{
return code;
}
#include "exec/softmmu-semi.h"
#endif
static target_ulong arm_semi_syscall_len;
#if !defined(CONFIG_USER_ONLY)
static target_ulong syscall_err;
#endif
static void arm_semi_cb(CPUState *cs, target_ulong ret, target_ulong err)
{
ARMCPU *cpu = ARM_CPU(cs);
CPUARMState *env = &cpu->env;
#ifdef CONFIG_USER_ONLY
TaskState *ts = cs->opaque;
#endif
target_ulong reg0 = is_a64(env) ? env->xregs[0] : env->regs[0];
if (ret == (target_ulong)-1) {
#ifdef CONFIG_USER_ONLY
ts->swi_errno = err;
#else
syscall_err = err;
#endif
reg0 = ret;
} else {
/* Fixup syscalls that use nonstardard return conventions. */
switch (reg0) {
case TARGET_SYS_WRITE:
case TARGET_SYS_READ:
reg0 = arm_semi_syscall_len - ret;
break;
case TARGET_SYS_SEEK:
reg0 = 0;
break;
default:
reg0 = ret;
break;
}
}
if (is_a64(env)) {
env->xregs[0] = reg0;
} else {
env->regs[0] = reg0;
}
}
static target_ulong arm_flen_buf(ARMCPU *cpu)
{
/* 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.
*/
CPUARMState *env = &cpu->env;
target_ulong sp;
if (is_a64(env)) {
sp = env->xregs[31];
} else {
sp = env->regs[13];
}
return sp - 64;
}
static void arm_semi_flen_cb(CPUState *cs, target_ulong ret, target_ulong err)
{
ARMCPU *cpu = ARM_CPU(cs);
CPUARMState *env = &cpu->env;
/* The size is always stored in big-endian order, extract
the value. We assume the size always fit in 32 bits. */
uint32_t size;
cpu_memory_rw_debug(cs, arm_flen_buf(cpu) + 32, (uint8_t *)&size, 4, 0);
size = be32_to_cpu(size);
if (is_a64(env)) {
env->xregs[0] = size;
} else {
env->regs[0] = size;
}
#ifdef CONFIG_USER_ONLY
((TaskState *)cs->opaque)->swi_errno = err;
#else
syscall_err = err;
#endif
}
static target_ulong arm_gdb_syscall(ARMCPU *cpu, gdb_syscall_complete_cb cb,
const char *fmt, ...)
{
va_list va;
CPUARMState *env = &cpu->env;
va_start(va, fmt);
gdb_do_syscallv(cb, fmt, va);
va_end(va);
/* FIXME: we are implicitly relying on the syscall completing
* before this point, which is not guaranteed. We should
* put in an explicit synchronization between this and
* the callback function.
*/
return is_a64(env) ? env->xregs[0] : env->regs[0];
}
/* Read the input value from the argument block; fail the semihosting
* call if the memory read fails.
*/
#define GET_ARG(n) do { \
if (is_a64(env)) { \
if (get_user_u64(arg ## n, args + (n) * 8)) { \
return -1; \
} \
} else { \
if (get_user_u32(arg ## n, args + (n) * 4)) { \
return -1; \
} \
} \
} while (0)
#define SET_ARG(n, val) \
(is_a64(env) ? \
put_user_u64(val, args + (n) * 8) : \
put_user_u32(val, args + (n) * 4))
/*
* 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. We use 0xdeadbeef as the return value
* when there isn't a defined return value for the call.
*/
target_ulong do_arm_semihosting(CPUARMState *env)
{
ARMCPU *cpu = arm_env_get_cpu(env);
CPUState *cs = CPU(cpu);
target_ulong args;
target_ulong arg0, arg1, arg2, arg3;
char * s;
int nr;
uint32_t ret;
uint32_t len;
#ifdef CONFIG_USER_ONLY
TaskState *ts = cs->opaque;
#else
CPUARMState *ts = env;
#endif
if (is_a64(env)) {
/* Note that the syscall number is in W0, not X0 */
nr = env->xregs[0] & 0xffffffffU;
args = env->xregs[1];
} else {
nr = env->regs[0];
args = env->regs[1];
}
switch (nr) {
case TARGET_SYS_OPEN:
GET_ARG(0);
GET_ARG(1);
GET_ARG(2);
s = lock_user_string(arg0);
if (!s) {
/* FIXME - should this error code be -TARGET_EFAULT ? */
return (uint32_t)-1;
}
if (arg1 >= 12) {
unlock_user(s, arg0, 0);
return (uint32_t)-1;
}
if (strcmp(s, ":tt") == 0) {
int result_fileno = arg1 < 4 ? STDIN_FILENO : STDOUT_FILENO;
unlock_user(s, arg0, 0);
return result_fileno;
}
if (use_gdb_syscalls()) {
ret = arm_gdb_syscall(cpu, arm_semi_cb, "open,%s,%x,1a4", arg0,
(int)arg2+1, gdb_open_modeflags[arg1]);
} else {
ret = set_swi_errno(ts, open(s, open_modeflags[arg1], 0644));
}
unlock_user(s, arg0, 0);
return ret;
case TARGET_SYS_CLOSE:
GET_ARG(0);
if (use_gdb_syscalls()) {
return arm_gdb_syscall(cpu, arm_semi_cb, "close,%x", arg0);
} else {
return set_swi_errno(ts, close(arg0));
}
case TARGET_SYS_WRITEC:
{
char c;
if (get_user_u8(c, args))
/* FIXME - should this error code be -TARGET_EFAULT ? */
return (uint32_t)-1;
/* Write to debug console. stderr is near enough. */
if (use_gdb_syscalls()) {
return arm_gdb_syscall(cpu, arm_semi_cb, "write,2,%x,1", args);
} else {
return write(STDERR_FILENO, &c, 1);
}
}
case TARGET_SYS_WRITE0:
if (!(s = lock_user_string(args)))
/* FIXME - should this error code be -TARGET_EFAULT ? */
return (uint32_t)-1;
len = strlen(s);
if (use_gdb_syscalls()) {
return arm_gdb_syscall(cpu, arm_semi_cb, "write,2,%x,%x",
args, len);
} else {
ret = write(STDERR_FILENO, s, len);
}
unlock_user(s, args, 0);
return ret;
case TARGET_SYS_WRITE:
GET_ARG(0);
GET_ARG(1);
GET_ARG(2);
len = arg2;
if (use_gdb_syscalls()) {
arm_semi_syscall_len = len;
return arm_gdb_syscall(cpu, arm_semi_cb, "write,%x,%x,%x",
arg0, arg1, len);
} else {
s = lock_user(VERIFY_READ, arg1, len, 1);
if (!s) {
/* FIXME - should this error code be -TARGET_EFAULT ? */
return (uint32_t)-1;
}
ret = set_swi_errno(ts, write(arg0, s, len));
unlock_user(s, arg1, 0);
if (ret == (uint32_t)-1)
return -1;
return len - ret;
}
case TARGET_SYS_READ:
GET_ARG(0);
GET_ARG(1);
GET_ARG(2);
len = arg2;
if (use_gdb_syscalls()) {
arm_semi_syscall_len = len;
return arm_gdb_syscall(cpu, arm_semi_cb, "read,%x,%x,%x",
arg0, arg1, len);
} else {
s = lock_user(VERIFY_WRITE, arg1, len, 0);
if (!s) {
/* FIXME - should this error code be -TARGET_EFAULT ? */
return (uint32_t)-1;
}
do {
ret = set_swi_errno(ts, read(arg0, s, len));
} while (ret == -1 && errno == EINTR);
unlock_user(s, arg1, len);
if (ret == (uint32_t)-1)
return -1;
return len - ret;
}
case TARGET_SYS_READC:
/* XXX: Read from debug console. Not implemented. */
return 0;
case TARGET_SYS_ISTTY:
GET_ARG(0);
if (use_gdb_syscalls()) {
return arm_gdb_syscall(cpu, arm_semi_cb, "isatty,%x", arg0);
} else {
return isatty(arg0);
}
case TARGET_SYS_SEEK:
GET_ARG(0);
GET_ARG(1);
if (use_gdb_syscalls()) {
return arm_gdb_syscall(cpu, arm_semi_cb, "lseek,%x,%x,0",
arg0, arg1);
} else {
ret = set_swi_errno(ts, lseek(arg0, arg1, SEEK_SET));
if (ret == (uint32_t)-1)
return -1;
return 0;
}
case TARGET_SYS_FLEN:
GET_ARG(0);
if (use_gdb_syscalls()) {
return arm_gdb_syscall(cpu, arm_semi_flen_cb, "fstat,%x,%x",
arg0, arm_flen_buf(cpu));
} else {
struct stat buf;
ret = set_swi_errno(ts, fstat(arg0, &buf));
if (ret == (uint32_t)-1)
return -1;
return buf.st_size;
}
case TARGET_SYS_TMPNAM:
/* XXX: Not implemented. */
return -1;
case TARGET_SYS_REMOVE:
GET_ARG(0);
GET_ARG(1);
if (use_gdb_syscalls()) {
ret = arm_gdb_syscall(cpu, arm_semi_cb, "unlink,%s",
arg0, (int)arg1+1);
} else {
s = lock_user_string(arg0);
if (!s) {
/* FIXME - should this error code be -TARGET_EFAULT ? */
return (uint32_t)-1;
}
ret = set_swi_errno(ts, remove(s));
unlock_user(s, arg0, 0);
}
return ret;
case TARGET_SYS_RENAME:
GET_ARG(0);
GET_ARG(1);
GET_ARG(2);
GET_ARG(3);
if (use_gdb_syscalls()) {
return arm_gdb_syscall(cpu, arm_semi_cb, "rename,%s,%s",
arg0, (int)arg1+1, arg2, (int)arg3+1);
} else {
char *s2;
s = lock_user_string(arg0);
s2 = lock_user_string(arg2);
if (!s || !s2)
/* FIXME - should this error code be -TARGET_EFAULT ? */
ret = (uint32_t)-1;
else
ret = set_swi_errno(ts, rename(s, s2));
if (s2)
unlock_user(s2, arg2, 0);
if (s)
unlock_user(s, arg0, 0);
return ret;
}
case TARGET_SYS_CLOCK:
return clock() / (CLOCKS_PER_SEC / 100);
case TARGET_SYS_TIME:
return set_swi_errno(ts, time(NULL));
case TARGET_SYS_SYSTEM:
GET_ARG(0);
GET_ARG(1);
if (use_gdb_syscalls()) {
return arm_gdb_syscall(cpu, arm_semi_cb, "system,%s",
arg0, (int)arg1+1);
} else {
s = lock_user_string(arg0);
if (!s) {
/* FIXME - should this error code be -TARGET_EFAULT ? */
return (uint32_t)-1;
}
ret = set_swi_errno(ts, system(s));
unlock_user(s, arg0, 0);
return ret;
}
case TARGET_SYS_ERRNO:
#ifdef CONFIG_USER_ONLY
return ts->swi_errno;
#else
return syscall_err;
#endif
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;
#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->arg_end - ts->info->arg_start;
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. */
return -1;
}
/* Adjust the command-line length. */
if (SET_ARG(1, output_size - 1)) {
/* Couldn't write back to argument block */
return -1;
}
/* Lock the buffer on the ARM side. */
output_buffer = lock_user(VERIFY_WRITE, arg0, output_size, 0);
if (!output_buffer) {
return -1;
}
/* 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_start,
output_size)) {
status = -1;
goto out;
}
/* 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);
return status;
}
case TARGET_SYS_HEAPINFO:
{
target_ulong retvals[4];
target_ulong limit;
int i;
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 + ARM_ANGEL_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
limit = ram_size;
/* TODO: Make this use the limit of the loaded application. */
retvals[0] = limit / 2;
retvals[1] = limit;
retvals[2] = limit; /* Stack base */
retvals[3] = 0; /* Stack limit. */
#endif
for (i = 0; i < ARRAY_SIZE(retvals); i++) {
bool fail;
if (is_a64(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 */
return -1;
}
}
return 0;
}
case TARGET_SYS_EXIT:
if (is_a64(env)) {
/*
* The A64 version of this call takes a parameter block,
* so the application-exit type can return a subcode which
* is the exit status code from the application.
*/
GET_ARG(0);
GET_ARG(1);
if (arg0 == ADP_Stopped_ApplicationExit) {
ret = arg1;
} else {
ret = 1;
}
} else {
/*
* ARM specifies only Stopped_ApplicationExit as normal
* exit, everything else is considered an error
*/
ret = (args == ADP_Stopped_ApplicationExit) ? 0 : 1;
}
gdb_exit(env, ret);
exit(ret);
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 (is_a64(env)) {
return 0;
}
/* fall through -- invalid for A32/T32 */
default:
fprintf(stderr, "qemu: Unsupported SemiHosting SWI 0x%02x\n", nr);
cpu_dump_state(cs, stderr, 0);
abort();
}
}
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