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/*
* Copyright (c) 2008 Jiri Svoboda
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/** @addtogroup generic
* @{
*/
/**
* @file
* @brief Udebug operations.
*
* Udebug operations on tasks and threads are implemented here. The
* functions defined here are called from the udebug_ipc module
* when servicing udebug IPC messages.
*/
#include <debug.h>
#include <proc/task.h>
#include <proc/thread.h>
#include <arch.h>
#include <errno.h>
#include <syscall/copy.h>
#include <ipc/ipc.h>
#include <udebug/udebug.h>
#include <udebug/udebug_ops.h>
/**
* Prepare a thread for a debugging operation.
*
* Simply put, return thread t with t->udebug.lock held,
* but only if it verifies all conditions.
*
* Specifically, verifies that thread t exists, is a userspace thread,
* and belongs to the current task (TASK). Verifies, that the thread
* is (or is not) go according to being_go (typically false).
* It also locks t->udebug.lock, making sure that t->udebug.active
* is true - that the thread is in a valid debugging session.
*
* With this verified and the t->udebug.lock mutex held, it is ensured
* that the thread cannot leave the debugging session, let alone cease
* to exist.
*
* In this function, holding the TASK->udebug.lock mutex prevents the
* thread from leaving the debugging session, while relaxing from
* the t->lock spinlock to the t->udebug.lock mutex.
*
* @param t Pointer, need not at all be valid.
* @param being_go Required thread state.
*
* Returns EOK if all went well, or an error code otherwise.
*/
static int _thread_op_begin(thread_t *t, bool being_go)
{
task_id_t taskid;
ipl_t ipl;
taskid = TASK->taskid;
mutex_lock(&TASK->udebug.lock);
/* thread_exists() must be called with threads_lock held */
ipl = interrupts_disable();
spinlock_lock(&threads_lock);
if (!thread_exists(t)) {
spinlock_unlock(&threads_lock);
interrupts_restore(ipl);
mutex_unlock(&TASK->udebug.lock);
return ENOENT;
}
/* t->lock is enough to ensure the thread's existence */
spinlock_lock(&t->lock);
spinlock_unlock(&threads_lock);
/* Verify that 't' is a userspace thread. */
if ((t->flags & THREAD_FLAG_USPACE) == 0) {
/* It's not, deny its existence */
spinlock_unlock(&t->lock);
interrupts_restore(ipl);
mutex_unlock(&TASK->udebug.lock);
return ENOENT;
}
/* Verify debugging state. */
if (t->udebug.active != true) {
/* Not in debugging session or undesired GO state */
spinlock_unlock(&t->lock);
interrupts_restore(ipl);
mutex_unlock(&TASK->udebug.lock);
return ENOENT;
}
/*
* Since the thread has active == true, TASK->udebug.lock
* is enough to ensure its existence and that active remains
* true.
*/
spinlock_unlock(&t->lock);
interrupts_restore(ipl);
/* Only mutex TASK->udebug.lock left. */
/* Now verify that the thread belongs to the current task. */
if (t->task != TASK) {
/* No such thread belonging this task*/
mutex_unlock(&TASK->udebug.lock);
return ENOENT;
}
/*
* Now we need to grab the thread's debug lock for synchronization
* of the threads stoppability/stop state.
*/
mutex_lock(&t->udebug.lock);
/* The big task mutex is no longer needed. */
mutex_unlock(&TASK->udebug.lock);
if (t->udebug.go != being_go) {
/* Not in debugging session or undesired GO state. */
mutex_unlock(&t->udebug.lock);
return EINVAL;
}
/* Only t->udebug.lock left. */
return EOK; /* All went well. */
}
/** End debugging operation on a thread. */
static void _thread_op_end(thread_t *t)
{
mutex_unlock(&t->udebug.lock);
}
/** Begin debugging the current task.
*
* Initiates a debugging session for the current task (and its threads).
* When the debugging session has started a reply will be sent to the
* UDEBUG_BEGIN call. This may happen immediately in this function if
* all the threads in this task are stoppable at the moment and in this
* case the function returns 1.
*
* Otherwise the function returns 0 and the reply will be sent as soon as
* all the threads become stoppable (i.e. they can be considered stopped).
*
* @param call The BEGIN call we are servicing.
* @return 0 (OK, but not done yet), 1 (done) or negative error code.
*/
int udebug_begin(call_t *call)
{
int reply;
thread_t *t;
link_t *cur;
LOG("udebug_begin()\n");
mutex_lock(&TASK->udebug.lock);
LOG("debugging task %llu\n", TASK->taskid);
if (TASK->udebug.dt_state != UDEBUG_TS_INACTIVE) {
mutex_unlock(&TASK->udebug.lock);
LOG("udebug_begin(): busy error\n");
return EBUSY;
}
TASK->udebug.dt_state = UDEBUG_TS_BEGINNING;
TASK->udebug.begin_call = call;
TASK->udebug.debugger = call->sender;
if (TASK->udebug.not_stoppable_count == 0) {
TASK->udebug.dt_state = UDEBUG_TS_ACTIVE;
TASK->udebug.begin_call = NULL;
reply = 1; /* immediate reply */
} else {
reply = 0; /* no reply */
}
/* Set udebug.active on all of the task's userspace threads. */
for (cur = TASK->th_head.next; cur != &TASK->th_head; cur = cur->next) {
t = list_get_instance(cur, thread_t, th_link);
mutex_lock(&t->udebug.lock);
if ((t->flags & THREAD_FLAG_USPACE) != 0)
t->udebug.active = true;
mutex_unlock(&t->udebug.lock);
}
mutex_unlock(&TASK->udebug.lock);
LOG("udebug_begin() done (%s)\n",
reply ? "reply" : "stoppability wait");
return reply;
}
/** Finish debugging the current task.
*
* Closes the debugging session for the current task.
* @return Zero on success or negative error code.
*/
int udebug_end(void)
{
int rc;
LOG("udebug_end()\n");
mutex_lock(&TASK->udebug.lock);
LOG("task %" PRIu64 "\n", TASK->taskid);
rc = udebug_task_cleanup(TASK);
mutex_unlock(&TASK->udebug.lock);
return rc;
}
/** Set the event mask.
*
* Sets the event mask that determines which events are enabled.
*
* @param mask Or combination of events that should be enabled.
* @return Zero on success or negative error code.
*/
int udebug_set_evmask(udebug_evmask_t mask)
{
LOG("udebug_set_mask()\n");
mutex_lock(&TASK->udebug.lock);
if (TASK->udebug.dt_state != UDEBUG_TS_ACTIVE) {
mutex_unlock(&TASK->udebug.lock);
LOG("udebug_set_mask(): not active debuging session\n");
return EINVAL;
}
TASK->udebug.evmask = mask;
mutex_unlock(&TASK->udebug.lock);
return 0;
}
/** Give thread GO.
*
* Upon recieving a go message, the thread is given GO. Being GO
* means the thread is allowed to execute userspace code (until
* a debugging event or STOP occurs, at which point the thread loses GO.
*
* @param t The thread to operate on (unlocked and need not be valid).
* @param call The GO call that we are servicing.
*/
int udebug_go(thread_t *t, call_t *call)
{
int rc;
/* On success, this will lock t->udebug.lock. */
rc = _thread_op_begin(t, false);
if (rc != EOK) {
return rc;
}
t->udebug.go_call = call;
t->udebug.go = true;
t->udebug.cur_event = 0; /* none */
/*
* Neither t's lock nor threads_lock may be held during wakeup.
*/
waitq_wakeup(&t->udebug.go_wq, WAKEUP_FIRST);
_thread_op_end(t);
return 0;
}
/** Stop a thread (i.e. take its GO away)
*
* Generates a STOP event as soon as the thread becomes stoppable (i.e.
* can be considered stopped).
*
* @param t The thread to operate on (unlocked and need not be valid).
* @param call The GO call that we are servicing.
*/
int udebug_stop(thread_t *t, call_t *call)
{
int rc;
LOG("udebug_stop()\n");
/*
* On success, this will lock t->udebug.lock. Note that this makes sure
* the thread is not stopped.
*/
rc = _thread_op_begin(t, true);
if (rc != EOK) {
return rc;
}
/* Take GO away from the thread. */
t->udebug.go = false;
if (t->udebug.stoppable != true) {
/* Answer will be sent when the thread becomes stoppable. */
_thread_op_end(t);
return 0;
}
/*
* Answer GO call.
*/
LOG("udebug_stop - answering go call\n");
/* Make sure nobody takes this call away from us. */
call = t->udebug.go_call;
t->udebug.go_call = NULL;
IPC_SET_RETVAL(call->data, 0);
IPC_SET_ARG1(call->data, UDEBUG_EVENT_STOP);
LOG("udebug_stop/ipc_answer\n");
THREAD->udebug.cur_event = UDEBUG_EVENT_STOP;
_thread_op_end(t);
mutex_lock(&TASK->udebug.lock);
ipc_answer(&TASK->answerbox, call);
mutex_unlock(&TASK->udebug.lock);
LOG("udebog_stop/done\n");
return 0;
}
/** Read the list of userspace threads in the current task.
*
* The list takes the form of a sequence of thread hashes (i.e. the pointers
* to thread structures). A buffer of size @a buf_size is allocated and
* a pointer to it written to @a buffer. The sequence of hashes is written
* into this buffer.
*
* If the sequence is longer than @a buf_size bytes, only as much hashes
* as can fit are copied. The number of thread hashes copied is stored
* in @a n.
*
* The rationale for having @a buf_size is that this function is only
* used for servicing the THREAD_READ message, which always specifies
* a maximum size for the userspace buffer.
*
* @param buffer The buffer for storing thread hashes.
* @param buf_size Buffer size in bytes.
* @param n The actual number of hashes copied will be stored here.
*/
int udebug_thread_read(void **buffer, size_t buf_size, size_t *n)
{
thread_t *t;
link_t *cur;
unative_t tid;
unsigned copied_ids;
ipl_t ipl;
unative_t *id_buffer;
int flags;
size_t max_ids;
LOG("udebug_thread_read()\n");
/* Allocate a buffer to hold thread IDs */
id_buffer = malloc(buf_size, 0);
mutex_lock(&TASK->udebug.lock);
/* Verify task state */
if (TASK->udebug.dt_state != UDEBUG_TS_ACTIVE) {
mutex_unlock(&TASK->udebug.lock);
return EINVAL;
}
ipl = interrupts_disable();
spinlock_lock(&TASK->lock);
/* Copy down the thread IDs */
max_ids = buf_size / sizeof(unative_t);
copied_ids = 0;
/* FIXME: make sure the thread isn't past debug shutdown... */
for (cur = TASK->th_head.next; cur != &TASK->th_head; cur = cur->next) {
/* Do not write past end of buffer */
if (copied_ids >= max_ids) break;
t = list_get_instance(cur, thread_t, th_link);
spinlock_lock(&t->lock);
flags = t->flags;
spinlock_unlock(&t->lock);
/* Not interested in kernel threads. */
if ((flags & THREAD_FLAG_USPACE) != 0) {
/* Using thread struct pointer as identification hash */
tid = (unative_t) t;
id_buffer[copied_ids++] = tid;
}
}
spinlock_unlock(&TASK->lock);
interrupts_restore(ipl);
mutex_unlock(&TASK->udebug.lock);
*buffer = id_buffer;
*n = copied_ids * sizeof(unative_t);
return 0;
}
/** Read the arguments of a system call.
*
* The arguments of the system call being being executed are copied
* to an allocated buffer and a pointer to it is written to @a buffer.
* The size of the buffer is exactly such that it can hold the maximum number
* of system-call arguments.
*
* Unless the thread is currently blocked in a SYSCALL_B or SYSCALL_E event,
* this function will fail with an EINVAL error code.
*
* @param buffer The buffer for storing thread hashes.
*/
int udebug_args_read(thread_t *t, void **buffer)
{
int rc;
unative_t *arg_buffer;
/* Prepare a buffer to hold the arguments. */
arg_buffer = malloc(6 * sizeof(unative_t), 0);
/* On success, this will lock t->udebug.lock. */
rc = _thread_op_begin(t, false);
if (rc != EOK) {
return rc;
}
/* Additionally we need to verify that we are inside a syscall. */
if (t->udebug.cur_event != UDEBUG_EVENT_SYSCALL_B &&
t->udebug.cur_event != UDEBUG_EVENT_SYSCALL_E) {
_thread_op_end(t);
return EINVAL;
}
/* Copy to a local buffer before releasing the lock. */
memcpy(arg_buffer, t->udebug.syscall_args, 6 * sizeof(unative_t));
_thread_op_end(t);
*buffer = arg_buffer;
return 0;
}
/** Read the memory of the debugged task.
*
* Reads @a n bytes from the address space of the debugged task, starting
* from @a uspace_addr. The bytes are copied into an allocated buffer
* and a pointer to it is written into @a buffer.
*
* @param uspace_addr Address from where to start reading.
* @param n Number of bytes to read.
* @param buffer For storing a pointer to the allocated buffer.
*/
int udebug_mem_read(unative_t uspace_addr, size_t n, void **buffer)
{
void *data_buffer;
int rc;
/* Verify task state */
mutex_lock(&TASK->udebug.lock);
if (TASK->udebug.dt_state != UDEBUG_TS_ACTIVE) {
mutex_unlock(&TASK->udebug.lock);
return EBUSY;
}
data_buffer = malloc(n, 0);
/* NOTE: this is not strictly from a syscall... but that shouldn't
* be a problem */
rc = copy_from_uspace(data_buffer, (void *)uspace_addr, n);
mutex_unlock(&TASK->udebug.lock);
if (rc != 0) return rc;
*buffer = data_buffer;
return 0;
}
/** @}
*/