/*
* 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 kernel_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 <stdbool.h>
#include <str.h>
#include <syscall/copy.h>
#include <ipc/ipc.h>
#include <udebug/udebug.h>
#include <udebug/udebug_ops.h>
#include <memw.h>
#include <stdlib.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 thread 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 errno_t _thread_op_begin(thread_t *thread, bool being_go)
{
mutex_lock(&TASK->udebug.lock);
thread = thread_try_get(thread);
if (!thread) {
mutex_unlock(&TASK->udebug.lock);
return ENOENT;
}
/* Verify that 'thread' is a userspace thread. */
if (!thread->uspace) {
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(&thread->udebug.lock);
/* Verify debugging state. */
if (thread->udebug.active != true) {
/* Not in debugging session or undesired GO state */
mutex_unlock(&thread->udebug.lock);
mutex_unlock(&TASK->udebug.lock);
return ENOENT;
}
/* Now verify that the thread belongs to the current task. */
if (thread->task != TASK) {
/* No such thread belonging this task */
mutex_unlock(&thread->udebug.lock);
mutex_unlock(&TASK->udebug.lock);
return ENOENT;
}
/* The big task mutex is no longer needed. */
mutex_unlock(&TASK->udebug.lock);
if (thread->udebug.go != being_go) {
/* Not in debugging session or undesired GO state. */
mutex_unlock(&thread->udebug.lock);
return EINVAL;
}
/* Only thread->udebug.lock left. */
return EOK; /* All went well. */
}
/** End debugging operation on a thread. */
static void _thread_op_end(thread_t *thread)
{
mutex_unlock(&thread->udebug.lock);
/* Drop reference from _thread_op_begin() */
thread_put(thread);
}
/** Begin debugging the current task.
*
* Initiates a debugging session for the current task (and its threads).
* When the debugging session has started a reply should 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 sets @a *active to @c true.
*
* Otherwise the function sets @a *active to false and the resonse should
* 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.
* @param active Place to store @c true iff we went directly to active state,
* @c false if we only went to beginning state
*
* @return EOK on success, EBUSY if the task is already has an active
* debugging session.
*/
errno_t udebug_begin(call_t *call, bool *active)
{
LOG("Debugging task %" PRIu64, TASK->taskid);
mutex_lock(&TASK->udebug.lock);
if (TASK->udebug.dt_state != UDEBUG_TS_INACTIVE) {
mutex_unlock(&TASK->udebug.lock);
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;
*active = true; /* directly to active state */
} else
*active = false; /* only in beginning state */
/* Set udebug.active on all of the task's userspace threads. */
list_foreach(TASK->threads, th_link, thread_t, thread) {
mutex_lock(&thread->udebug.lock);
if (thread->uspace) {
thread->udebug.active = true;
mutex_unlock(&thread->udebug.lock);
condvar_broadcast(&thread->udebug.active_cv);
} else
mutex_unlock(&thread->udebug.lock);
}
mutex_unlock(&TASK->udebug.lock);
return EOK;
}
/** Finish debugging the current task.
*
* Closes the debugging session for the current task.
*
* @return Zero on success or an error code.
*
*/
errno_t udebug_end(void)
{
LOG("Task %" PRIu64, TASK->taskid);
mutex_lock(&TASK->udebug.lock);
errno_t 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 an error code.
*
*/
errno_t udebug_set_evmask(udebug_evmask_t mask)
{
LOG("mask = 0x%x", mask);
mutex_lock(&TASK->udebug.lock);
if (TASK->udebug.dt_state != UDEBUG_TS_ACTIVE) {
mutex_unlock(&TASK->udebug.lock);
return EINVAL;
}
TASK->udebug.evmask = mask;
mutex_unlock(&TASK->udebug.lock);
return EOK;
}
/** 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 thread The thread to operate on (unlocked and need not be valid).
* @param call The GO call that we are servicing.
*
*/
errno_t udebug_go(thread_t *thread, call_t *call)
{
/* On success, this will lock thread->udebug.lock. */
errno_t rc = _thread_op_begin(thread, false);
if (rc != EOK)
return rc;
thread->udebug.go_call = call;
thread->udebug.go = true;
thread->udebug.cur_event = 0; /* none */
/*
* Neither thread's lock nor threads_lock may be held during wakeup.
*
*/
waitq_wake_all(&thread->udebug.go_wq);
_thread_op_end(thread);
return EOK;
}
/** 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 thread The thread to operate on (unlocked and need not be valid).
* @param call The GO call that we are servicing.
*
*/
errno_t udebug_stop(thread_t *thread, call_t *call)
{
LOG("udebug_stop()");
/*
* On success, this will lock thread->udebug.lock. Note that this
* makes sure the thread is not stopped.
*
*/
errno_t rc = _thread_op_begin(thread, true);
if (rc != EOK)
return rc;
/* Take GO away from the thread. */
thread->udebug.go = false;
if (thread->udebug.stoppable != true) {
/* Answer will be sent when the thread becomes stoppable. */
_thread_op_end(thread);
return EOK;
}
/*
* Answer GO call.
*
*/
/* Make sure nobody takes this call away from us. */
call = thread->udebug.go_call;
thread->udebug.go_call = NULL;
ipc_set_retval(&call->data, 0);
ipc_set_arg1(&call->data, UDEBUG_EVENT_STOP);
THREAD->udebug.cur_event = UDEBUG_EVENT_STOP;
_thread_op_end(thread);
mutex_lock(&TASK->udebug.lock);
ipc_answer(&TASK->answerbox, call);
mutex_unlock(&TASK->udebug.lock);
return EOK;
}
/** 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 bytes copied is stored in @a stored.
* The total number of thread bytes that could have been saved had there been
* enough space is stored in @a needed.
*
* 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 stored The actual number of bytes copied will be stored here.
* @param needed Total number of hashes that could have been saved.
*
*/
errno_t udebug_thread_read(void **buffer, size_t buf_size, size_t *stored,
size_t *needed)
{
LOG("udebug_thread_read()");
/* Allocate a buffer to hold thread IDs */
sysarg_t *id_buffer = malloc(buf_size + 1);
if (!id_buffer)
return ENOMEM;
mutex_lock(&TASK->udebug.lock);
/* Verify task state */
if (TASK->udebug.dt_state != UDEBUG_TS_ACTIVE) {
mutex_unlock(&TASK->udebug.lock);
free(id_buffer);
return EINVAL;
}
irq_spinlock_lock(&TASK->lock, true);
/* Copy down the thread IDs */
size_t max_ids = buf_size / sizeof(sysarg_t);
size_t copied_ids = 0;
size_t extra_ids = 0;
/* FIXME: make sure the thread isn't past debug shutdown... */
list_foreach(TASK->threads, th_link, thread_t, thread) {
bool uspace = thread->uspace;
/* Not interested in kernel threads. */
if (!uspace)
continue;
if (copied_ids < max_ids) {
/* Using thread struct pointer as identification hash */
id_buffer[copied_ids++] = (sysarg_t) thread;
} else
extra_ids++;
}
irq_spinlock_unlock(&TASK->lock, true);
mutex_unlock(&TASK->udebug.lock);
*buffer = id_buffer;
*stored = copied_ids * sizeof(sysarg_t);
*needed = (copied_ids + extra_ids) * sizeof(sysarg_t);
return EOK;
}
/** Read task name.
*
* Returns task name as non-terminated string in a newly allocated buffer.
* Also returns the size of the data.
*
* @param data Place to store pointer to newly allocated block.
* @param data_size Place to store size of the data.
*
* @return EOK on success, ENOMEM if memory allocation failed.
*
*/
errno_t udebug_name_read(char **data, size_t *data_size)
{
size_t name_size = str_size(TASK->name) + 1;
*data = malloc(name_size);
if (!*data)
return ENOMEM;
*data_size = name_size;
memcpy(*data, TASK->name, name_size);
return EOK;
}
/** 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 thread Thread where call arguments are to be read.
* @param buffer Place to store pointer to new buffer.
*
* @return EOK on success, ENOENT if @a t is invalid, EINVAL
* if thread state is not valid for this operation.
*
*/
errno_t udebug_args_read(thread_t *thread, void **buffer)
{
/* On success, this will lock t->udebug.lock. */
errno_t rc = _thread_op_begin(thread, false);
if (rc != EOK)
return rc;
/* Additionally we need to verify that we are inside a syscall. */
if ((thread->udebug.cur_event != UDEBUG_EVENT_SYSCALL_B) &&
(thread->udebug.cur_event != UDEBUG_EVENT_SYSCALL_E)) {
_thread_op_end(thread);
return EINVAL;
}
/* Prepare a buffer to hold the arguments. */
sysarg_t *arg_buffer = malloc(6 * sizeof(sysarg_t));
if (!arg_buffer) {
_thread_op_end(thread);
return ENOMEM;
}
/* Copy to a local buffer before releasing the lock. */
memcpy(arg_buffer, thread->udebug.syscall_args, 6 * sizeof(sysarg_t));
_thread_op_end(thread);
*buffer = arg_buffer;
return EOK;
}
/** Read the register state of the thread.
*
* The contents of the thread's istate structure are copied to a newly
* allocated buffer and a pointer to it is written to @a buffer. The size of
* the buffer will be sizeof(istate_t).
*
* Currently register state cannot be read if the thread is inside a system
* call (as opposed to an exception). This is an implementation limit.
*
* @param thread Thread whose state is to be read.
* @param buffer Place to store pointer to new buffer.
*
* @return EOK on success, ENOENT if @a t is invalid, EINVAL
* if thread is not in valid state, EBUSY if istate
* is not available.
*
*/
errno_t udebug_regs_read(thread_t *thread, void **buffer)
{
/* On success, this will lock t->udebug.lock */
errno_t rc = _thread_op_begin(thread, false);
if (rc != EOK)
return rc;
istate_t *state = thread->udebug.uspace_state;
if (state == NULL) {
_thread_op_end(thread);
return EBUSY;
}
/* Prepare a buffer to hold the data. */
istate_t *state_buf = malloc(sizeof(istate_t));
if (!state_buf) {
_thread_op_end(thread);
return ENOMEM;
}
/* Copy to the allocated buffer */
memcpy(state_buf, state, sizeof(istate_t));
_thread_op_end(thread);
*buffer = (void *) state_buf;
return EOK;
}
/** 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.
*
*/
errno_t udebug_mem_read(uspace_addr_t uspace_addr, size_t n, void **buffer)
{
/* Verify task state */
mutex_lock(&TASK->udebug.lock);
if (TASK->udebug.dt_state != UDEBUG_TS_ACTIVE) {
mutex_unlock(&TASK->udebug.lock);
return EBUSY;
}
void *data_buffer = malloc(n);
if (!data_buffer) {
mutex_unlock(&TASK->udebug.lock);
return ENOMEM;
}
/*
* NOTE: this is not strictly from a syscall... but that shouldn't
* be a problem
*
*/
errno_t rc = copy_from_uspace(data_buffer, uspace_addr, n);
mutex_unlock(&TASK->udebug.lock);
if (rc != EOK)
return rc;
*buffer = data_buffer;
return EOK;
}
/** @}
*/