diff mbox series

[10/33] linux-user: Split out brk, close, exit, read, write

Message ID 20180601073050.8054-11-richard.henderson@linaro.org
State New
Headers show
Series linux-user: Begin splitting do_syscall | expand

Commit Message

Richard Henderson June 1, 2018, 7:30 a.m. UTC
These are relatively simple unconditionally defined syscalls.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

---
 linux-user/syscall.c | 198 ++++++++++++++++++++++++-------------------
 1 file changed, 111 insertions(+), 87 deletions(-)

-- 
2.17.0

Comments

Laurent Vivier June 4, 2018, 8:17 p.m. UTC | #1
Le 01/06/2018 à 09:30, Richard Henderson a écrit :
> These are relatively simple unconditionally defined syscalls.

> 

> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

> ---

>  linux-user/syscall.c | 198 ++++++++++++++++++++++++-------------------

>  1 file changed, 111 insertions(+), 87 deletions(-)

> 

> diff --git a/linux-user/syscall.c b/linux-user/syscall.c

> index fc3dc3f40d..b0d268dab7 100644

> --- a/linux-user/syscall.c

> +++ b/linux-user/syscall.c

> @@ -7984,6 +7984,112 @@ IMPL(enosys)

>      return do_unimplemented(num);

>  }

>  

> +IMPL(brk)

> +{

> +    return do_brk(arg1);

> +}

> +

> +IMPL(close)

> +{

> +    if (is_hostfd(arg1)) {

> +        return -TARGET_EBADF;

> +    }

> +    fd_trans_unregister(arg1);

> +    return get_errno(close(arg1));

> +}

> +

> +IMPL(exit)

> +{

> +    CPUState *cpu = ENV_GET_CPU(cpu_env);

> +

> +    /* In old applications this may be used to implement _exit(2).

> +       However in threaded applictions it is used for thread termination,

> +       and _exit_group is used for application termination.

> +       Do thread termination if we have more then one thread.  */

> +    if (block_signals()) {

> +        return -TARGET_ERESTARTSYS;

> +    }

> +

> +    cpu_list_lock();

> +

> +    if (CPU_NEXT(first_cpu)) {

> +        /* Remove the CPU from the list.  */

> +        QTAILQ_REMOVE(&cpus, cpu, node);

> +        cpu_list_unlock();

> +

> +        TaskState *ts = cpu->opaque;

> +        if (ts->child_tidptr) {

> +            put_user_u32(0, ts->child_tidptr);

> +            sys_futex(g2h(ts->child_tidptr), FUTEX_WAKE, INT_MAX,

> +                      NULL, NULL, 0);

> +        }

> +        thread_cpu = NULL;

> +        object_unref(OBJECT(cpu));

> +        g_free(ts);

> +        rcu_unregister_thread();

> +        pthread_exit(NULL);

> +    } else {

> +        cpu_list_unlock();

> +

> +#ifdef TARGET_GPROF

> +        _mcleanup();

> +#endif

> +        gdb_exit(cpu_env, arg1);

> +        _exit(arg1);

> +    }

> +    g_assert_not_reached();

> +}

> +

> +IMPL(read)

> +{

> +    abi_long ret;

> +    char *fn;

> +

> +    if (arg3 == 0) {

> +        return 0;

> +    }

> +    if (is_hostfd(arg1)) {

> +        return -TARGET_EBADF;

> +    }

> +    fn = lock_user(VERIFY_WRITE, arg2, arg3, 0);

> +    if (!fn) {

> +        return -TARGET_EFAULT;

> +    }

> +    ret = get_errno(safe_read(arg1, fn, arg3));

> +    if (ret >= 0 && fd_trans_host_to_target_data(arg1)) {

> +        ret = fd_trans_host_to_target_data(arg1)(fn, ret);

> +    }

> +    unlock_user(fn, arg2, ret);

> +    return ret;

> +}

> +

> +IMPL(write)

> +{

> +    abi_long ret;

> +    char *fn;

> +

> +    if (is_hostfd(arg1)) {

> +        return -TARGET_EBADF;

> +    }

> +    fn = lock_user(VERIFY_READ, arg2, arg3, 1);

> +    if (!fn) {

> +        return -TARGET_EFAULT;

> +    }

> +    if (fd_trans_target_to_host_data(arg1)) {

> +        void *copy = g_malloc(arg3);

> +        memcpy(copy, fn, arg3);

> +        ret = fd_trans_target_to_host_data(arg1)(copy, arg3);

> +        if (ret >= 0) {

> +            ret = get_errno(safe_write(arg1, copy, ret));

> +        }

> +        g_free(copy);

> +    } else {

> +        ret = get_errno(safe_write(arg1, fn, arg3));

> +    }

> +    unlock_user(fn, arg2, ret);

> +    return ret;

> +}

> +

>  /* This is an internal helper for do_syscall so that it is easier

>   * to have a single return point, so that actions, such as logging

>   * of syscall results, can be performed.

> @@ -7999,83 +8105,6 @@ IMPL(everything_else)

>      char *fn;

>  

>      switch(num) {

> -    case TARGET_NR_exit:

> -        /* In old applications this may be used to implement _exit(2).

> -           However in threaded applictions it is used for thread termination,

> -           and _exit_group is used for application termination.

> -           Do thread termination if we have more then one thread.  */

> -

> -        if (block_signals()) {

> -            return -TARGET_ERESTARTSYS;

> -        }

> -

> -        cpu_list_lock();

> -

> -        if (CPU_NEXT(first_cpu)) {

> -            TaskState *ts;

> -

> -            /* Remove the CPU from the list.  */

> -            QTAILQ_REMOVE(&cpus, cpu, node);

> -

> -            cpu_list_unlock();

> -

> -            ts = cpu->opaque;

> -            if (ts->child_tidptr) {

> -                put_user_u32(0, ts->child_tidptr);

> -                sys_futex(g2h(ts->child_tidptr), FUTEX_WAKE, INT_MAX,

> -                          NULL, NULL, 0);

> -            }

> -            thread_cpu = NULL;

> -            object_unref(OBJECT(cpu));

> -            g_free(ts);

> -            rcu_unregister_thread();

> -            pthread_exit(NULL);

> -        }

> -

> -        cpu_list_unlock();

> -#ifdef TARGET_GPROF

> -        _mcleanup();

> -#endif

> -        gdb_exit(cpu_env, arg1);

> -        _exit(arg1);

> -        return 0; /* avoid warning */

> -    case TARGET_NR_read:

> -        if (arg3 == 0) {

> -            return 0;

> -        } else {

> -            if (is_hostfd(arg1)) {

> -                return -TARGET_EBADF;

> -            }

> -            if (!(p = lock_user(VERIFY_WRITE, arg2, arg3, 0)))

> -                return -TARGET_EFAULT;

> -            ret = get_errno(safe_read(arg1, p, arg3));

> -            if (ret >= 0 &&

> -                fd_trans_host_to_target_data(arg1)) {

> -                ret = fd_trans_host_to_target_data(arg1)(p, ret);

> -            }

> -            unlock_user(p, arg2, ret);

> -        }

> -        return ret;

> -    case TARGET_NR_write:

> -        if (is_hostfd(arg1)) {

> -            return -TARGET_EBADF;

> -        }

> -        if (!(p = lock_user(VERIFY_READ, arg2, arg3, 1)))

> -            return -TARGET_EFAULT;

> -        if (fd_trans_target_to_host_data(arg1)) {

> -            void *copy = g_malloc(arg3);

> -            memcpy(copy, p, arg3);

> -            ret = fd_trans_target_to_host_data(arg1)(copy, arg3);

> -            if (ret >= 0) {

> -                ret = get_errno(safe_write(arg1, copy, ret));

> -            }

> -            g_free(copy);

> -        } else {

> -            ret = get_errno(safe_write(arg1, p, arg3));

> -        }

> -        unlock_user(p, arg2, 0);

> -        return ret;

> -

>  #ifdef TARGET_NR_open

>      case TARGET_NR_open:

>          if (!(p = lock_user_string(arg1)))

> @@ -8116,15 +8145,6 @@ IMPL(everything_else)

>          fd_trans_unregister(ret);

>          return ret;

>  #endif

> -    case TARGET_NR_close:

> -        if (is_hostfd(arg1)) {

> -            return -TARGET_EBADF;

> -        }

> -        fd_trans_unregister(arg1);

> -        return get_errno(close(arg1));

> -

> -    case TARGET_NR_brk:

> -        return do_brk(arg1);

>  #ifdef TARGET_NR_fork

>      case TARGET_NR_fork:

>          return get_errno(do_fork(cpu_env, TARGET_SIGCHLD, 0, 0, 0, 0));

> @@ -12894,7 +12914,11 @@ IMPL(everything_else)

>  }

>  

>  static impl_fn * const syscall_table[] = {

> -    impl_everything_else,

> +    [TARGET_NR_brk] = impl_brk,

> +    [TARGET_NR_close] = impl_close,

> +    [TARGET_NR_exit] = impl_exit,

> +    [TARGET_NR_read] = impl_read,

> +    [TARGET_NR_write] = impl_write,

>  };

>  

>  abi_long do_syscall(void *cpu_env, unsigned num, abi_long arg1,

> 


Starting with this patch, this is broken...

For instance with ppc64le target:

qemu: Unsupported syscall: 33
qemu: Unsupported syscall: 33
qemu: Unsupported syscall: 5
qemu: Unsupported syscall: 5
qemu: Unsupported syscall: 5
qemu: Unsupported syscall: 5
qemu: Unsupported syscall: 5
qemu: Unsupported syscall: 5
qemu: Unsupported syscall: 5
qemu: Unsupported syscall: 5
qemu: Unsupported syscall: 5
/bin/uname: error while loading shared libraries: libc.so.6: cannot open
shared object file: Error 38

for instance, for num = TARGET_NR_OPEN:

+    impl_fn *fn = impl_everything_else;

-> fn = impl_everything_else

+    if (num < ARRAY_SIZE(syscall_table)) {
+        fn = syscall_table[num];

-> fn = NULL

+    }
+    if (fn == NULL) {
+        fn = impl_enosys;

-> fn = impl_enosys;

+    }

So all undefined syscall numbers < max(defined syscall numbers) will
call impl_enosys.

You should do

    fn = NULL;
    if (num < ARRAY_SIZE(syscall_table)) {
        fn = syscall_table[num];
    }
    if (fn == NULL) {
        fn = impl_eveything_else;
    }

and the impl_enosys is managed by impl_eveything_else.

You can come back to your initial code when all syscalls are split out
(when you remove the enosys case from everything_else)... otherwise we
will not be able to bisect this part in the future.

Thanks,
Laurent
Richard Henderson June 4, 2018, 9:01 p.m. UTC | #2
On 06/04/2018 01:17 PM, Laurent Vivier wrote:
> Le 01/06/2018 à 09:30, Richard Henderson a écrit :

>> These are relatively simple unconditionally defined syscalls.

>>

>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

>> ---

>>  linux-user/syscall.c | 198 ++++++++++++++++++++++++-------------------

>>  1 file changed, 111 insertions(+), 87 deletions(-)

>>

>> diff --git a/linux-user/syscall.c b/linux-user/syscall.c

>> index fc3dc3f40d..b0d268dab7 100644

>> --- a/linux-user/syscall.c

>> +++ b/linux-user/syscall.c

>> @@ -7984,6 +7984,112 @@ IMPL(enosys)

>>      return do_unimplemented(num);

>>  }

>>  

>> +IMPL(brk)

>> +{

>> +    return do_brk(arg1);

>> +}

>> +

>> +IMPL(close)

>> +{

>> +    if (is_hostfd(arg1)) {

>> +        return -TARGET_EBADF;

>> +    }

>> +    fd_trans_unregister(arg1);

>> +    return get_errno(close(arg1));

>> +}

>> +

>> +IMPL(exit)

>> +{

>> +    CPUState *cpu = ENV_GET_CPU(cpu_env);

>> +

>> +    /* In old applications this may be used to implement _exit(2).

>> +       However in threaded applictions it is used for thread termination,

>> +       and _exit_group is used for application termination.

>> +       Do thread termination if we have more then one thread.  */

>> +    if (block_signals()) {

>> +        return -TARGET_ERESTARTSYS;

>> +    }

>> +

>> +    cpu_list_lock();

>> +

>> +    if (CPU_NEXT(first_cpu)) {

>> +        /* Remove the CPU from the list.  */

>> +        QTAILQ_REMOVE(&cpus, cpu, node);

>> +        cpu_list_unlock();

>> +

>> +        TaskState *ts = cpu->opaque;

>> +        if (ts->child_tidptr) {

>> +            put_user_u32(0, ts->child_tidptr);

>> +            sys_futex(g2h(ts->child_tidptr), FUTEX_WAKE, INT_MAX,

>> +                      NULL, NULL, 0);

>> +        }

>> +        thread_cpu = NULL;

>> +        object_unref(OBJECT(cpu));

>> +        g_free(ts);

>> +        rcu_unregister_thread();

>> +        pthread_exit(NULL);

>> +    } else {

>> +        cpu_list_unlock();

>> +

>> +#ifdef TARGET_GPROF

>> +        _mcleanup();

>> +#endif

>> +        gdb_exit(cpu_env, arg1);

>> +        _exit(arg1);

>> +    }

>> +    g_assert_not_reached();

>> +}

>> +

>> +IMPL(read)

>> +{

>> +    abi_long ret;

>> +    char *fn;

>> +

>> +    if (arg3 == 0) {

>> +        return 0;

>> +    }

>> +    if (is_hostfd(arg1)) {

>> +        return -TARGET_EBADF;

>> +    }

>> +    fn = lock_user(VERIFY_WRITE, arg2, arg3, 0);

>> +    if (!fn) {

>> +        return -TARGET_EFAULT;

>> +    }

>> +    ret = get_errno(safe_read(arg1, fn, arg3));

>> +    if (ret >= 0 && fd_trans_host_to_target_data(arg1)) {

>> +        ret = fd_trans_host_to_target_data(arg1)(fn, ret);

>> +    }

>> +    unlock_user(fn, arg2, ret);

>> +    return ret;

>> +}

>> +

>> +IMPL(write)

>> +{

>> +    abi_long ret;

>> +    char *fn;

>> +

>> +    if (is_hostfd(arg1)) {

>> +        return -TARGET_EBADF;

>> +    }

>> +    fn = lock_user(VERIFY_READ, arg2, arg3, 1);

>> +    if (!fn) {

>> +        return -TARGET_EFAULT;

>> +    }

>> +    if (fd_trans_target_to_host_data(arg1)) {

>> +        void *copy = g_malloc(arg3);

>> +        memcpy(copy, fn, arg3);

>> +        ret = fd_trans_target_to_host_data(arg1)(copy, arg3);

>> +        if (ret >= 0) {

>> +            ret = get_errno(safe_write(arg1, copy, ret));

>> +        }

>> +        g_free(copy);

>> +    } else {

>> +        ret = get_errno(safe_write(arg1, fn, arg3));

>> +    }

>> +    unlock_user(fn, arg2, ret);

>> +    return ret;

>> +}

>> +

>>  /* This is an internal helper for do_syscall so that it is easier

>>   * to have a single return point, so that actions, such as logging

>>   * of syscall results, can be performed.

>> @@ -7999,83 +8105,6 @@ IMPL(everything_else)

>>      char *fn;

>>  

>>      switch(num) {

>> -    case TARGET_NR_exit:

>> -        /* In old applications this may be used to implement _exit(2).

>> -           However in threaded applictions it is used for thread termination,

>> -           and _exit_group is used for application termination.

>> -           Do thread termination if we have more then one thread.  */

>> -

>> -        if (block_signals()) {

>> -            return -TARGET_ERESTARTSYS;

>> -        }

>> -

>> -        cpu_list_lock();

>> -

>> -        if (CPU_NEXT(first_cpu)) {

>> -            TaskState *ts;

>> -

>> -            /* Remove the CPU from the list.  */

>> -            QTAILQ_REMOVE(&cpus, cpu, node);

>> -

>> -            cpu_list_unlock();

>> -

>> -            ts = cpu->opaque;

>> -            if (ts->child_tidptr) {

>> -                put_user_u32(0, ts->child_tidptr);

>> -                sys_futex(g2h(ts->child_tidptr), FUTEX_WAKE, INT_MAX,

>> -                          NULL, NULL, 0);

>> -            }

>> -            thread_cpu = NULL;

>> -            object_unref(OBJECT(cpu));

>> -            g_free(ts);

>> -            rcu_unregister_thread();

>> -            pthread_exit(NULL);

>> -        }

>> -

>> -        cpu_list_unlock();

>> -#ifdef TARGET_GPROF

>> -        _mcleanup();

>> -#endif

>> -        gdb_exit(cpu_env, arg1);

>> -        _exit(arg1);

>> -        return 0; /* avoid warning */

>> -    case TARGET_NR_read:

>> -        if (arg3 == 0) {

>> -            return 0;

>> -        } else {

>> -            if (is_hostfd(arg1)) {

>> -                return -TARGET_EBADF;

>> -            }

>> -            if (!(p = lock_user(VERIFY_WRITE, arg2, arg3, 0)))

>> -                return -TARGET_EFAULT;

>> -            ret = get_errno(safe_read(arg1, p, arg3));

>> -            if (ret >= 0 &&

>> -                fd_trans_host_to_target_data(arg1)) {

>> -                ret = fd_trans_host_to_target_data(arg1)(p, ret);

>> -            }

>> -            unlock_user(p, arg2, ret);

>> -        }

>> -        return ret;

>> -    case TARGET_NR_write:

>> -        if (is_hostfd(arg1)) {

>> -            return -TARGET_EBADF;

>> -        }

>> -        if (!(p = lock_user(VERIFY_READ, arg2, arg3, 1)))

>> -            return -TARGET_EFAULT;

>> -        if (fd_trans_target_to_host_data(arg1)) {

>> -            void *copy = g_malloc(arg3);

>> -            memcpy(copy, p, arg3);

>> -            ret = fd_trans_target_to_host_data(arg1)(copy, arg3);

>> -            if (ret >= 0) {

>> -                ret = get_errno(safe_write(arg1, copy, ret));

>> -            }

>> -            g_free(copy);

>> -        } else {

>> -            ret = get_errno(safe_write(arg1, p, arg3));

>> -        }

>> -        unlock_user(p, arg2, 0);

>> -        return ret;

>> -

>>  #ifdef TARGET_NR_open

>>      case TARGET_NR_open:

>>          if (!(p = lock_user_string(arg1)))

>> @@ -8116,15 +8145,6 @@ IMPL(everything_else)

>>          fd_trans_unregister(ret);

>>          return ret;

>>  #endif

>> -    case TARGET_NR_close:

>> -        if (is_hostfd(arg1)) {

>> -            return -TARGET_EBADF;

>> -        }

>> -        fd_trans_unregister(arg1);

>> -        return get_errno(close(arg1));

>> -

>> -    case TARGET_NR_brk:

>> -        return do_brk(arg1);

>>  #ifdef TARGET_NR_fork

>>      case TARGET_NR_fork:

>>          return get_errno(do_fork(cpu_env, TARGET_SIGCHLD, 0, 0, 0, 0));

>> @@ -12894,7 +12914,11 @@ IMPL(everything_else)

>>  }

>>  

>>  static impl_fn * const syscall_table[] = {

>> -    impl_everything_else,

>> +    [TARGET_NR_brk] = impl_brk,

>> +    [TARGET_NR_close] = impl_close,

>> +    [TARGET_NR_exit] = impl_exit,

>> +    [TARGET_NR_read] = impl_read,

>> +    [TARGET_NR_write] = impl_write,

>>  };

>>  

>>  abi_long do_syscall(void *cpu_env, unsigned num, abi_long arg1,

>>

> 

> Starting with this patch, this is broken...

> 

> For instance with ppc64le target:

> 

> qemu: Unsupported syscall: 33

> qemu: Unsupported syscall: 33

> qemu: Unsupported syscall: 5

> qemu: Unsupported syscall: 5

> qemu: Unsupported syscall: 5

> qemu: Unsupported syscall: 5

> qemu: Unsupported syscall: 5

> qemu: Unsupported syscall: 5

> qemu: Unsupported syscall: 5

> qemu: Unsupported syscall: 5

> qemu: Unsupported syscall: 5

> /bin/uname: error while loading shared libraries: libc.so.6: cannot open

> shared object file: Error 38

> 

> for instance, for num = TARGET_NR_OPEN:

> 

> +    impl_fn *fn = impl_everything_else;

> 

> -> fn = impl_everything_else

> 

> +    if (num < ARRAY_SIZE(syscall_table)) {

> +        fn = syscall_table[num];

> 

> -> fn = NULL

> 

> +    }

> +    if (fn == NULL) {

> +        fn = impl_enosys;

> 

> -> fn = impl_enosys;

> 

> +    }

> 

> So all undefined syscall numbers < max(defined syscall numbers) will

> call impl_enosys.

> 

> You should do

> 

>     fn = NULL;

>     if (num < ARRAY_SIZE(syscall_table)) {

>         fn = syscall_table[num];

>     }

>     if (fn == NULL) {

>         fn = impl_eveything_else;

>     }

> 

> and the impl_enosys is managed by impl_eveything_else.

> 

> You can come back to your initial code when all syscalls are split out

> (when you remove the enosys case from everything_else)... otherwise we

> will not be able to bisect this part in the future.


Ack.  How did my testing not catch this.  Will fix.


r~
diff mbox series

Patch

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index fc3dc3f40d..b0d268dab7 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -7984,6 +7984,112 @@  IMPL(enosys)
     return do_unimplemented(num);
 }
 
+IMPL(brk)
+{
+    return do_brk(arg1);
+}
+
+IMPL(close)
+{
+    if (is_hostfd(arg1)) {
+        return -TARGET_EBADF;
+    }
+    fd_trans_unregister(arg1);
+    return get_errno(close(arg1));
+}
+
+IMPL(exit)
+{
+    CPUState *cpu = ENV_GET_CPU(cpu_env);
+
+    /* In old applications this may be used to implement _exit(2).
+       However in threaded applictions it is used for thread termination,
+       and _exit_group is used for application termination.
+       Do thread termination if we have more then one thread.  */
+    if (block_signals()) {
+        return -TARGET_ERESTARTSYS;
+    }
+
+    cpu_list_lock();
+
+    if (CPU_NEXT(first_cpu)) {
+        /* Remove the CPU from the list.  */
+        QTAILQ_REMOVE(&cpus, cpu, node);
+        cpu_list_unlock();
+
+        TaskState *ts = cpu->opaque;
+        if (ts->child_tidptr) {
+            put_user_u32(0, ts->child_tidptr);
+            sys_futex(g2h(ts->child_tidptr), FUTEX_WAKE, INT_MAX,
+                      NULL, NULL, 0);
+        }
+        thread_cpu = NULL;
+        object_unref(OBJECT(cpu));
+        g_free(ts);
+        rcu_unregister_thread();
+        pthread_exit(NULL);
+    } else {
+        cpu_list_unlock();
+
+#ifdef TARGET_GPROF
+        _mcleanup();
+#endif
+        gdb_exit(cpu_env, arg1);
+        _exit(arg1);
+    }
+    g_assert_not_reached();
+}
+
+IMPL(read)
+{
+    abi_long ret;
+    char *fn;
+
+    if (arg3 == 0) {
+        return 0;
+    }
+    if (is_hostfd(arg1)) {
+        return -TARGET_EBADF;
+    }
+    fn = lock_user(VERIFY_WRITE, arg2, arg3, 0);
+    if (!fn) {
+        return -TARGET_EFAULT;
+    }
+    ret = get_errno(safe_read(arg1, fn, arg3));
+    if (ret >= 0 && fd_trans_host_to_target_data(arg1)) {
+        ret = fd_trans_host_to_target_data(arg1)(fn, ret);
+    }
+    unlock_user(fn, arg2, ret);
+    return ret;
+}
+
+IMPL(write)
+{
+    abi_long ret;
+    char *fn;
+
+    if (is_hostfd(arg1)) {
+        return -TARGET_EBADF;
+    }
+    fn = lock_user(VERIFY_READ, arg2, arg3, 1);
+    if (!fn) {
+        return -TARGET_EFAULT;
+    }
+    if (fd_trans_target_to_host_data(arg1)) {
+        void *copy = g_malloc(arg3);
+        memcpy(copy, fn, arg3);
+        ret = fd_trans_target_to_host_data(arg1)(copy, arg3);
+        if (ret >= 0) {
+            ret = get_errno(safe_write(arg1, copy, ret));
+        }
+        g_free(copy);
+    } else {
+        ret = get_errno(safe_write(arg1, fn, arg3));
+    }
+    unlock_user(fn, arg2, ret);
+    return ret;
+}
+
 /* This is an internal helper for do_syscall so that it is easier
  * to have a single return point, so that actions, such as logging
  * of syscall results, can be performed.
@@ -7999,83 +8105,6 @@  IMPL(everything_else)
     char *fn;
 
     switch(num) {
-    case TARGET_NR_exit:
-        /* In old applications this may be used to implement _exit(2).
-           However in threaded applictions it is used for thread termination,
-           and _exit_group is used for application termination.
-           Do thread termination if we have more then one thread.  */
-
-        if (block_signals()) {
-            return -TARGET_ERESTARTSYS;
-        }
-
-        cpu_list_lock();
-
-        if (CPU_NEXT(first_cpu)) {
-            TaskState *ts;
-
-            /* Remove the CPU from the list.  */
-            QTAILQ_REMOVE(&cpus, cpu, node);
-
-            cpu_list_unlock();
-
-            ts = cpu->opaque;
-            if (ts->child_tidptr) {
-                put_user_u32(0, ts->child_tidptr);
-                sys_futex(g2h(ts->child_tidptr), FUTEX_WAKE, INT_MAX,
-                          NULL, NULL, 0);
-            }
-            thread_cpu = NULL;
-            object_unref(OBJECT(cpu));
-            g_free(ts);
-            rcu_unregister_thread();
-            pthread_exit(NULL);
-        }
-
-        cpu_list_unlock();
-#ifdef TARGET_GPROF
-        _mcleanup();
-#endif
-        gdb_exit(cpu_env, arg1);
-        _exit(arg1);
-        return 0; /* avoid warning */
-    case TARGET_NR_read:
-        if (arg3 == 0) {
-            return 0;
-        } else {
-            if (is_hostfd(arg1)) {
-                return -TARGET_EBADF;
-            }
-            if (!(p = lock_user(VERIFY_WRITE, arg2, arg3, 0)))
-                return -TARGET_EFAULT;
-            ret = get_errno(safe_read(arg1, p, arg3));
-            if (ret >= 0 &&
-                fd_trans_host_to_target_data(arg1)) {
-                ret = fd_trans_host_to_target_data(arg1)(p, ret);
-            }
-            unlock_user(p, arg2, ret);
-        }
-        return ret;
-    case TARGET_NR_write:
-        if (is_hostfd(arg1)) {
-            return -TARGET_EBADF;
-        }
-        if (!(p = lock_user(VERIFY_READ, arg2, arg3, 1)))
-            return -TARGET_EFAULT;
-        if (fd_trans_target_to_host_data(arg1)) {
-            void *copy = g_malloc(arg3);
-            memcpy(copy, p, arg3);
-            ret = fd_trans_target_to_host_data(arg1)(copy, arg3);
-            if (ret >= 0) {
-                ret = get_errno(safe_write(arg1, copy, ret));
-            }
-            g_free(copy);
-        } else {
-            ret = get_errno(safe_write(arg1, p, arg3));
-        }
-        unlock_user(p, arg2, 0);
-        return ret;
-
 #ifdef TARGET_NR_open
     case TARGET_NR_open:
         if (!(p = lock_user_string(arg1)))
@@ -8116,15 +8145,6 @@  IMPL(everything_else)
         fd_trans_unregister(ret);
         return ret;
 #endif
-    case TARGET_NR_close:
-        if (is_hostfd(arg1)) {
-            return -TARGET_EBADF;
-        }
-        fd_trans_unregister(arg1);
-        return get_errno(close(arg1));
-
-    case TARGET_NR_brk:
-        return do_brk(arg1);
 #ifdef TARGET_NR_fork
     case TARGET_NR_fork:
         return get_errno(do_fork(cpu_env, TARGET_SIGCHLD, 0, 0, 0, 0));
@@ -12894,7 +12914,11 @@  IMPL(everything_else)
 }
 
 static impl_fn * const syscall_table[] = {
-    impl_everything_else,
+    [TARGET_NR_brk] = impl_brk,
+    [TARGET_NR_close] = impl_close,
+    [TARGET_NR_exit] = impl_exit,
+    [TARGET_NR_read] = impl_read,
+    [TARGET_NR_write] = impl_write,
 };
 
 abi_long do_syscall(void *cpu_env, unsigned num, abi_long arg1,