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semihosting: Split out semihost_sys_read 

Split out the non-ARM specific portions of SYS_READ to a
reusable function.  This handles all GuestFD.  Isolate the
curious ARM-specific return value processing to a new
callback, common_semi_rw_cb.

Note that gdb_do_syscall %x reads target_ulong, not int.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2022-04-28 11:40:41 -07:00
parent 5eadbbfca6
commit af0484b502
3 changed files with 113 additions and 65 deletions
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8
include/semihosting/syscalls.h
View File

@ -18,6 +18,8 @@
* or non-zero (where it should include the terminating zero).
*/
typedef struct GuestFD GuestFD;
void semihost_sys_open(CPUState *cs, gdb_syscall_complete_cb complete,
target_ulong fname, target_ulong fname_len,
int gdb_flags, int mode);
@ -25,4 +27,10 @@ void semihost_sys_open(CPUState *cs, gdb_syscall_complete_cb complete,
void semihost_sys_close(CPUState *cs, gdb_syscall_complete_cb complete,
int fd);
void semihost_sys_read(CPUState *cs, gdb_syscall_complete_cb complete,
int fd, target_ulong buf, target_ulong len);
void semihost_sys_read_gf(CPUState *cs, gdb_syscall_complete_cb complete,
GuestFD *gf, target_ulong buf, target_ulong len);
#endif /* SEMIHOSTING_SYSCALLS_H */

85
semihosting/arm-compat-semi.c
View File

@ -231,7 +231,6 @@ static void common_semi_cb(CPUState *cs, target_ulong ret, target_ulong err)
target_ulong reg0 = common_semi_arg(cs, 0);
switch (reg0) {
case TARGET_SYS_WRITE:
case TARGET_SYS_READ:
ret = common_semi_syscall_len - ret;
break;
case TARGET_SYS_SEEK:
@ -244,6 +243,25 @@ static void common_semi_cb(CPUState *cs, target_ulong ret, target_ulong err)
common_semi_set_ret(cs, ret);
}
/*
* 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, target_ulong ret, target_ulong 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);
}
/*
* Return an address in target memory of 64 bytes where the remote
* gdb should write its stat struct. (The format of this structure
@ -278,8 +296,6 @@ common_semi_flen_cb(CPUState *cs, target_ulong ret, target_ulong err)
*/
typedef void sys_writefn(CPUState *cs, GuestFD *gf,
target_ulong buf, uint32_t len);
typedef void sys_readfn(CPUState *cs, GuestFD *gf,
target_ulong buf, uint32_t len);
typedef void sys_isattyfn(CPUState *cs, GuestFD *gf);
typedef void sys_seekfn(CPUState *cs, GuestFD *gf, target_ulong offset);
typedef void sys_flenfn(CPUState *cs, GuestFD *gf);
@ -302,26 +318,6 @@ static void host_writefn(CPUState *cs, GuestFD *gf,
common_semi_cb(cs, len - ret, 0);
}
static void host_readfn(CPUState *cs, GuestFD *gf,
target_ulong buf, uint32_t len)
{
CPUArchState *env = cs->env_ptr;
uint32_t ret = 0;
char *s = lock_user(VERIFY_WRITE, buf, len, 0);
(void) env; /* Used in arm softmmu lock_user implicitly */
if (s) {
do {
ret = read(gf->hostfd, s, len);
} while (ret == -1 && errno == EINTR);
unlock_user(s, buf, len);
if (ret == (uint32_t)-1) {
ret = 0;
}
}
/* Return bytes not read, on error as well. */
common_semi_cb(cs, len - ret, 0);
}
static void host_isattyfn(CPUState *cs, GuestFD *gf)
{
common_semi_cb(cs, isatty(gf->hostfd), 0);
@ -351,13 +347,6 @@ static void gdb_writefn(CPUState *cs, GuestFD *gf,
gdb_do_syscall(common_semi_cb, "write,%x,%x,%x", gf->hostfd, buf, len);
}
static void gdb_readfn(CPUState *cs, GuestFD *gf,
target_ulong buf, uint32_t len)
{
common_semi_syscall_len = len;
gdb_do_syscall(common_semi_cb, "read,%x,%x,%x", gf->hostfd, buf, len);
}
static void gdb_isattyfn(CPUState *cs, GuestFD *gf)
{
gdb_do_syscall(common_semi_cb, "isatty,%x", gf->hostfd);
@ -398,30 +387,6 @@ static void staticfile_writefn(CPUState *cs, GuestFD *gf,
common_semi_cb(cs, -1, EBADF);
}
static void staticfile_readfn(CPUState *cs, GuestFD *gf,
target_ulong buf, uint32_t len)
{
CPUArchState *env = cs->env_ptr;
uint32_t i = 0;
char *s;
(void) env; /* Used in arm softmmu lock_user implicitly */
s = lock_user(VERIFY_WRITE, buf, len, 0);
if (s) {
for (i = 0; i < len; i++) {
if (gf->staticfile.off >= gf->staticfile.len) {
break;
}
s[i] = gf->staticfile.data[gf->staticfile.off];
gf->staticfile.off++;
}
unlock_user(s, buf, len);
}
/* Return number of bytes not read */
common_semi_cb(cs, len - i, 0);
}
static void staticfile_isattyfn(CPUState *cs, GuestFD *gf)
{
common_semi_cb(cs, 0, 0);
@ -440,7 +405,6 @@ static void staticfile_flenfn(CPUState *cs, GuestFD *gf)
typedef struct GuestFDFunctions {
sys_writefn *writefn;
sys_readfn *readfn;
sys_isattyfn *isattyfn;
sys_seekfn *seekfn;
sys_flenfn *flenfn;
@ -449,21 +413,18 @@ typedef struct GuestFDFunctions {
static const GuestFDFunctions guestfd_fns[] = {
[GuestFDHost] = {
.writefn = host_writefn,
.readfn = host_readfn,
.isattyfn = host_isattyfn,
.seekfn = host_seekfn,
.flenfn = host_flenfn,
},
[GuestFDGDB] = {
.writefn = gdb_writefn,
.readfn = gdb_readfn,
.isattyfn = gdb_isattyfn,
.seekfn = gdb_seekfn,
.flenfn = gdb_flenfn,
},
[GuestFDStatic] = {
.writefn = staticfile_writefn,
.readfn = staticfile_readfn,
.isattyfn = staticfile_isattyfn,
.seekfn = staticfile_seekfn,
.flenfn = staticfile_flenfn,
@ -583,13 +544,7 @@ void do_common_semihosting(CPUState *cs)
GET_ARG(0);
GET_ARG(1);
GET_ARG(2);
len = arg2;
gf = get_guestfd(arg0);
if (!gf) {
goto do_badf;
}
guestfd_fns[gf->type].readfn(cs, gf, arg1, len);
semihost_sys_read(cs, common_semi_rw_cb, arg0, arg1, arg2);
break;
case TARGET_SYS_READC:

85
semihosting/syscalls.c
View File

@ -100,6 +100,13 @@ static void gdb_close(CPUState *cs, gdb_syscall_complete_cb complete,
gdb_do_syscall(complete, "close,%x", (target_ulong)gf->hostfd);
}
static void gdb_read(CPUState *cs, gdb_syscall_complete_cb complete,
GuestFD *gf, target_ulong buf, target_ulong len)
{
gdb_do_syscall(complete, "read,%x,%x,%x",
(target_ulong)gf->hostfd, buf, len);
}
/*
* Host semihosting syscall implementations.
*/
@ -163,6 +170,54 @@ static void host_close(CPUState *cs, gdb_syscall_complete_cb complete,
}
}
static void host_read(CPUState *cs, gdb_syscall_complete_cb complete,
GuestFD *gf, target_ulong buf, target_ulong len)
{
CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
void *ptr = lock_user(VERIFY_WRITE, buf, len, 0);
ssize_t ret;
if (!ptr) {
complete(cs, -1, EFAULT);
return;
}
do {
ret = read(gf->hostfd, ptr, len);
} while (ret == -1 && errno == EINTR);
if (ret == -1) {
complete(cs, -1, errno);
unlock_user(ptr, buf, 0);
} else {
complete(cs, ret, 0);
unlock_user(ptr, buf, ret);
}
}
/*
* Static file semihosting syscall implementations.
*/
static void staticfile_read(CPUState *cs, gdb_syscall_complete_cb complete,
GuestFD *gf, target_ulong buf, target_ulong len)
{
CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
target_ulong rest = gf->staticfile.len - gf->staticfile.off;
void *ptr;
if (len > rest) {
len = rest;
}
ptr = lock_user(VERIFY_WRITE, buf, len, 0);
if (!ptr) {
complete(cs, -1, EFAULT);
return;
}
memcpy(ptr, gf->staticfile.data + gf->staticfile.off, len);
gf->staticfile.off += len;
complete(cs, len, 0);
unlock_user(ptr, buf, len);
}
/*
* Syscall entry points.
*/
@ -201,3 +256,33 @@ void semihost_sys_close(CPUState *cs, gdb_syscall_complete_cb complete, int fd)
}
dealloc_guestfd(fd);
}
void semihost_sys_read_gf(CPUState *cs, gdb_syscall_complete_cb complete,
GuestFD *gf, target_ulong buf, target_ulong len)
{
switch (gf->type) {
case GuestFDGDB:
gdb_read(cs, complete, gf, buf, len);
break;
case GuestFDHost:
host_read(cs, complete, gf, buf, len);
break;
case GuestFDStatic:
staticfile_read(cs, complete, gf, buf, len);
break;
default:
g_assert_not_reached();
}
}
void semihost_sys_read(CPUState *cs, gdb_syscall_complete_cb complete,
int fd, target_ulong buf, target_ulong len)
{
GuestFD *gf = get_guestfd(fd);
if (gf) {
semihost_sys_read_gf(cs, complete, gf, buf, len);
} else {
complete(cs, -1, EBADF);
}
}