Skip to content

Commit

Permalink
target/arm/arm-semi: Restrict use of TaskState*
Browse files Browse the repository at this point in the history 
The semihosting code needs accuss to the linux-user only
TaskState pointer so it can set the semihosting errno per-thread
for linux-user mode. At the moment we do this by having some
ifdefs so that we define a 'ts' local in do_arm_semihosting()
which is either a real TaskState * or just a CPUARMState *,
depending on which mode we're compiling for.

This is awkward if we want to refactor do_arm_semihosting()
into other functions which might need to be passed the TaskState.
Restrict usage of the TaskState local by:
 * making set_swi_errno() always take the CPUARMState pointer
   and (for the linux-user version) get TaskState from that
 * creating a new get_swi_errno() which reads the errno
 * having the two semihosting calls which need the TaskState
   for other purposes (SYS_GET_CMDLINE and SYS_HEAPINFO)
   define a variable with scope restricted to just that code

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20190916141544.17540-6-peter.maydell@linaro.org
  • Loading branch information
@pm215
pm215 committed Oct 15, 2019
1 parent 35e9a0a commit 6ed6845
Showing 1 changed file with 63 additions and 48 deletions.
111 changes: 63 additions & 48 deletions target/arm/arm-semi.c
View file
Expand Up @@ -213,26 +213,45 @@ static GuestFD *get_guestfd(int guestfd)
return gf;
}

#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
/*
* 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 "exec/softmmu-semi.h"
#endif

static inline uint32_t set_swi_errno(CPUARMState *env, uint32_t code)
{
if (code == (uint32_t)-1) {
#ifdef CONFIG_USER_ONLY
CPUState *cs = env_cpu(env);
TaskState *ts = cs->opaque;

ts->swi_errno = errno;
#else
syscall_err = errno;
#endif
}
return code;
}

#include "exec/softmmu-semi.h"
static inline uint32_t get_swi_errno(CPUARMState *env)
{
#ifdef CONFIG_USER_ONLY
CPUState *cs = env_cpu(env);
TaskState *ts = cs->opaque;

return ts->swi_errno;
#else
return syscall_err;
#endif
}

static target_ulong arm_semi_syscall_len;

Expand Down Expand Up @@ -379,12 +398,12 @@ static target_ulong arm_gdb_syscall(ARMCPU *cpu, gdb_syscall_complete_cb cb,
if (is_a64(env)) { \
if (get_user_u64(arg ## n, args + (n) * 8)) { \
errno = EFAULT; \
return set_swi_errno(ts, -1); \
return set_swi_errno(env, -1); \
} \
} else { \
if (get_user_u32(arg ## n, args + (n) * 4)) { \
errno = EFAULT; \
return set_swi_errno(ts, -1); \
return set_swi_errno(env, -1); \
} \
} \
} while (0)
Expand Down Expand Up @@ -413,11 +432,6 @@ target_ulong do_arm_semihosting(CPUARMState *env)
int nr;
uint32_t ret;
uint32_t len;
#ifdef CONFIG_USER_ONLY
TaskState *ts = cs->opaque;
#else
CPUARMState *ts = env;
#endif
GuestFD *gf;

if (is_a64(env)) {
Expand All @@ -440,19 +454,19 @@ target_ulong do_arm_semihosting(CPUARMState *env)
s = lock_user_string(arg0);
if (!s) {
errno = EFAULT;
return set_swi_errno(ts, -1);
return set_swi_errno(env, -1);
}
if (arg1 >= 12) {
unlock_user(s, arg0, 0);
errno = EINVAL;
return set_swi_errno(ts, -1);
return set_swi_errno(env, -1);
}

guestfd = alloc_guestfd();
if (guestfd < 0) {
unlock_user(s, arg0, 0);
errno = EMFILE;
return set_swi_errno(ts, -1);
return set_swi_errno(env, -1);
}

if (strcmp(s, ":tt") == 0) {
Expand All @@ -466,7 +480,7 @@ target_ulong do_arm_semihosting(CPUARMState *env)
ret = arm_gdb_syscall(cpu, arm_semi_open_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));
ret = set_swi_errno(env, open(s, open_modeflags[arg1], 0644));
if (ret == (uint32_t)-1) {
dealloc_guestfd(guestfd);
} else {
Expand All @@ -483,13 +497,13 @@ target_ulong do_arm_semihosting(CPUARMState *env)
gf = get_guestfd(arg0);
if (!gf) {
errno = EBADF;
return set_swi_errno(ts, -1);
return set_swi_errno(env, -1);
}

if (use_gdb_syscalls()) {
ret = arm_gdb_syscall(cpu, arm_semi_cb, "close,%x", gf->hostfd);
} else {
ret = set_swi_errno(ts, close(gf->hostfd));
ret = set_swi_errno(env, close(gf->hostfd));
}
dealloc_guestfd(arg0);
return ret;
Expand All @@ -507,7 +521,7 @@ target_ulong do_arm_semihosting(CPUARMState *env)
gf = get_guestfd(arg0);
if (!gf) {
errno = EBADF;
return set_swi_errno(ts, -1);
return set_swi_errno(env, -1);
}

if (use_gdb_syscalls()) {
Expand All @@ -520,7 +534,7 @@ target_ulong do_arm_semihosting(CPUARMState *env)
/* Return bytes not written on error */
return len;
}
ret = set_swi_errno(ts, write(gf->hostfd, s, len));
ret = set_swi_errno(env, write(gf->hostfd, s, len));
unlock_user(s, arg1, 0);
if (ret == (uint32_t)-1) {
ret = 0;
Expand All @@ -537,7 +551,7 @@ target_ulong do_arm_semihosting(CPUARMState *env)
gf = get_guestfd(arg0);
if (!gf) {
errno = EBADF;
return set_swi_errno(ts, -1);
return set_swi_errno(env, -1);
}

if (use_gdb_syscalls()) {
Expand All @@ -551,7 +565,7 @@ target_ulong do_arm_semihosting(CPUARMState *env)
return len;
}
do {
ret = set_swi_errno(ts, read(gf->hostfd, s, len));
ret = set_swi_errno(env, read(gf->hostfd, s, len));
} while (ret == -1 && errno == EINTR);
unlock_user(s, arg1, len);
if (ret == (uint32_t)-1) {
Expand All @@ -569,7 +583,7 @@ target_ulong do_arm_semihosting(CPUARMState *env)
gf = get_guestfd(arg0);
if (!gf) {
errno = EBADF;
return set_swi_errno(ts, -1);
return set_swi_errno(env, -1);
}

if (use_gdb_syscalls()) {
Expand All @@ -584,14 +598,14 @@ target_ulong do_arm_semihosting(CPUARMState *env)
gf = get_guestfd(arg0);
if (!gf) {
errno = EBADF;
return set_swi_errno(ts, -1);
return set_swi_errno(env, -1);
}

if (use_gdb_syscalls()) {
return arm_gdb_syscall(cpu, arm_semi_cb, "lseek,%x,%x,0",
gf->hostfd, arg1);
} else {
ret = set_swi_errno(ts, lseek(gf->hostfd, arg1, SEEK_SET));
ret = set_swi_errno(env, lseek(gf->hostfd, arg1, SEEK_SET));
if (ret == (uint32_t)-1)
return -1;
return 0;
Expand All @@ -602,15 +616,15 @@ target_ulong do_arm_semihosting(CPUARMState *env)
gf = get_guestfd(arg0);
if (!gf) {
errno = EBADF;
return set_swi_errno(ts, -1);
return set_swi_errno(env, -1);
}

if (use_gdb_syscalls()) {
return arm_gdb_syscall(cpu, arm_semi_flen_cb, "fstat,%x,%x",
gf->hostfd, arm_flen_buf(cpu));
} else {
struct stat buf;
ret = set_swi_errno(ts, fstat(gf->hostfd, &buf));
ret = set_swi_errno(env, fstat(gf->hostfd, &buf));
if (ret == (uint32_t)-1)
return -1;
return buf.st_size;
Expand All @@ -628,9 +642,9 @@ target_ulong do_arm_semihosting(CPUARMState *env)
s = lock_user_string(arg0);
if (!s) {
errno = EFAULT;
return set_swi_errno(ts, -1);
return set_swi_errno(env, -1);
}
ret = set_swi_errno(ts, remove(s));
ret = set_swi_errno(env, remove(s));
unlock_user(s, arg0, 0);
}
return ret;
Expand All @@ -648,9 +662,9 @@ target_ulong do_arm_semihosting(CPUARMState *env)
s2 = lock_user_string(arg2);
if (!s || !s2) {
errno = EFAULT;
ret = set_swi_errno(ts, -1);
ret = set_swi_errno(env, -1);
} else {
ret = set_swi_errno(ts, rename(s, s2));
ret = set_swi_errno(env, rename(s, s2));
}
if (s2)
unlock_user(s2, arg2, 0);
Expand All @@ -661,7 +675,7 @@ target_ulong do_arm_semihosting(CPUARMState *env)
case TARGET_SYS_CLOCK:
return clock() / (CLOCKS_PER_SEC / 100);
case TARGET_SYS_TIME:
return set_swi_errno(ts, time(NULL));
return set_swi_errno(env, time(NULL));
case TARGET_SYS_SYSTEM:
GET_ARG(0);
GET_ARG(1);
Expand All @@ -672,18 +686,14 @@ target_ulong do_arm_semihosting(CPUARMState *env)
s = lock_user_string(arg0);
if (!s) {
errno = EFAULT;
return set_swi_errno(ts, -1);
return set_swi_errno(env, -1);
}
ret = set_swi_errno(ts, system(s));
ret = set_swi_errno(env, 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
return get_swi_errno(env);
case TARGET_SYS_GET_CMDLINE:
{
/* Build a command-line from the original argv.
Expand All @@ -706,6 +716,8 @@ target_ulong do_arm_semihosting(CPUARMState *env)
int status = 0;
#if !defined(CONFIG_USER_ONLY)
const char *cmdline;
#else
TaskState *ts = cs->opaque;
#endif
GET_ARG(0);
GET_ARG(1);
Expand Down Expand Up @@ -733,21 +745,21 @@ target_ulong do_arm_semihosting(CPUARMState *env)
if (output_size > input_size) {
/* Not enough space to store command-line arguments. */
errno = E2BIG;
return set_swi_errno(ts, -1);
return set_swi_errno(env, -1);
}

/* Adjust the command-line length. */
if (SET_ARG(1, output_size - 1)) {
/* Couldn't write back to argument block */
errno = EFAULT;
return set_swi_errno(ts, -1);
return set_swi_errno(env, -1);
}

/* Lock the buffer on the ARM side. */
output_buffer = lock_user(VERIFY_WRITE, arg0, output_size, 0);
if (!output_buffer) {
errno = EFAULT;
return set_swi_errno(ts, -1);
return set_swi_errno(env, -1);
}

/* Copy the command-line arguments. */
Expand All @@ -763,7 +775,7 @@ target_ulong do_arm_semihosting(CPUARMState *env)
if (copy_from_user(output_buffer, ts->info->arg_start,
output_size)) {
errno = EFAULT;
status = set_swi_errno(ts, -1);
status = set_swi_errno(env, -1);
goto out;
}

Expand All @@ -785,6 +797,9 @@ target_ulong do_arm_semihosting(CPUARMState *env)
target_ulong retvals[4];
target_ulong limit;
int i;
#ifdef CONFIG_USER_ONLY
TaskState *ts = cs->opaque;
#endif

GET_ARG(0);

Expand Down Expand Up @@ -834,7 +849,7 @@ target_ulong do_arm_semihosting(CPUARMState *env)
if (fail) {
/* Couldn't write back to argument block */
errno = EFAULT;
return set_swi_errno(ts, -1);
return set_swi_errno(env, -1);
}
}
return 0;
Expand Down

0 comments on commit 6ed6845

Please sign in to comment.