minix/lib/libblockdriver/trace.c

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/* This file implements block level tracing support. */
#include <minix/drivers.h>
#include <minix/blockdriver_mt.h>
#include <minix/btrace.h>
#include <sys/ioc_block.h>
#include <minix/minlib.h>
#include <assert.h>
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#include "const.h"
#include "trace.h"
#define NO_TRACEDEV ((dev_t) -1)
#define NO_TIME ((u32_t) -1)
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static int trace_enabled = FALSE;
static dev_t trace_dev = NO_TRACEDEV;
static btrace_entry *trace_buf = NULL;
static size_t trace_size = 0;
static size_t trace_pos;
static size_t trace_next;
static u64_t trace_tsc;
/* Pointers to in-progress trace entries for each thread (all worker threads,
* plus one for the main thread). Each pointer is set to NULL whenever no
* operation is currently being traced for that thread, for whatever reason.
*/
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static btrace_entry *trace_ptr[MAX_THREADS + 1] = { NULL };
/*===========================================================================*
* trace_gettime *
*===========================================================================*/
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static u32_t trace_gettime(void)
{
/* Return the current time, in microseconds since the start of the trace.
*/
u64_t tsc;
assert(trace_enabled);
read_tsc_64(&tsc);
tsc = sub64(tsc, trace_tsc);
return tsc_64_to_micros(tsc);
}
/*===========================================================================*
* trace_ctl *
*===========================================================================*/
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int trace_ctl(dev_t minor, unsigned int request, endpoint_t endpt,
cp_grant_id_t grant)
{
/* Process a block trace control request.
*/
size_t size;
int r, ctl, entries;
switch (request) {
case BIOCTRACEBUF:
/* The size cannot be changed when tracing is enabled. */
if (trace_enabled) return EBUSY;
/* Copy in the requested size. */
if ((r = sys_safecopyfrom(endpt, grant, 0, (vir_bytes) &size,
sizeof(size))) != OK)
return r;
if (size >= INT_MAX / sizeof(btrace_entry)) return EINVAL;
/* The size can only be set or reset, not changed. */
if (size > 0 && trace_size > 0) return EBUSY;
/* Allocate or free a buffer for tracing data. For future multi-device
* tracing support, the buffer is associated with a minor device.
*/
if (size == 0) {
if (trace_dev == NO_TRACEDEV) return OK;
if (trace_dev != minor) return EINVAL;
free(trace_buf);
trace_dev = NO_TRACEDEV;
} else {
if ((trace_buf = malloc(size * sizeof(btrace_entry))) == NULL)
return errno;
trace_dev = minor;
}
trace_size = size;
trace_pos = 0;
trace_next = 0;
return OK;
case BIOCTRACECTL:
/* We can only start/stop tracing if the given device has a trace
* buffer associated with it.
*/
if (trace_dev != minor) return EINVAL;
/* Copy in the request code. */
if ((r = sys_safecopyfrom(endpt, grant, 0, (vir_bytes) &ctl,
sizeof(ctl))) != OK)
return r;
/* Start or stop tracing. */
switch (ctl) {
case BTCTL_START:
if (trace_enabled) return EBUSY;
read_tsc_64(&trace_tsc);
trace_enabled = TRUE;
break;
case BTCTL_STOP:
if (!trace_enabled) return EINVAL;
trace_enabled = FALSE;
/* Cancel all ongoing trace operations. */
memset(trace_ptr, 0, sizeof(trace_ptr));
break;
default:
return EINVAL;
}
return OK;
case BIOCTRACEGET:
/* We can only retrieve tracing entries if the given device has a trace
* buffer associated with it.
*/
if (trace_dev != minor) return EINVAL;
if (trace_enabled) return EBUSY;
/* How much can we copy out? */
entries = MIN(trace_pos - trace_next,
_MINIX_IOCTL_SIZE_BIG(request) / sizeof(btrace_entry));
if (entries == 0)
return 0;
if ((r = sys_safecopyto(endpt, grant, 0,
(vir_bytes) &trace_buf[trace_next],
entries * sizeof(btrace_entry))) != OK)
return r;
trace_next += entries;
return entries;
}
return EINVAL;
}
/*===========================================================================*
* trace_start *
*===========================================================================*/
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void trace_start(thread_id_t id, message *m_ptr)
{
/* Start creating a trace entry.
*/
btrace_entry *entry;
int req;
u64_t pos;
size_t size;
int flags;
if (!trace_enabled || trace_dev != m_ptr->BDEV_MINOR) return;
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assert(id >= 0 && id < MAX_THREADS + 1);
if (trace_pos == trace_size)
return;
switch (m_ptr->m_type) {
case BDEV_OPEN: req = BTREQ_OPEN; break;
case BDEV_CLOSE: req = BTREQ_CLOSE; break;
case BDEV_READ: req = BTREQ_READ; break;
case BDEV_WRITE: req = BTREQ_WRITE; break;
case BDEV_GATHER: req = BTREQ_GATHER; break;
case BDEV_SCATTER: req = BTREQ_SCATTER; break;
case BDEV_IOCTL: req = BTREQ_IOCTL; break;
default: return;
}
switch (m_ptr->m_type) {
case BDEV_OPEN:
case BDEV_CLOSE:
pos = cvu64(0);
size = m_ptr->BDEV_ACCESS;
flags = 0;
break;
case BDEV_READ:
case BDEV_WRITE:
case BDEV_GATHER:
case BDEV_SCATTER:
pos = make64(m_ptr->BDEV_POS_LO, m_ptr->BDEV_POS_HI);
size = m_ptr->BDEV_COUNT;
flags = m_ptr->BDEV_FLAGS;
break;
case BDEV_IOCTL:
pos = cvu64(0);
size = m_ptr->BDEV_REQUEST;
flags = 0;
/* Do not log trace control requests. */
switch (size) {
case BIOCTRACEBUF:
case BIOCTRACECTL:
case BIOCTRACEGET:
return;
}
break;
default:
/* Do not log any other messages. */
return;
}
entry = &trace_buf[trace_pos];
entry->request = req;
entry->size = size;
entry->position = pos;
entry->flags = flags;
entry->result = BTRES_INPROGRESS;
entry->start_time = trace_gettime();
entry->finish_time = NO_TIME;
trace_ptr[id] = entry;
trace_pos++;
}
/*===========================================================================*
* trace_setsize *
*===========================================================================*/
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void trace_setsize(thread_id_t id, size_t size)
{
/* Set the current trace entry's actual (byte) size, for vector requests.
*/
btrace_entry *entry;
if (!trace_enabled) return;
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assert(id >= 0 && id < MAX_THREADS + 1);
if ((entry = trace_ptr[id]) == NULL) return;
entry->size = size;
}
/*===========================================================================*
* trace_finish *
*===========================================================================*/
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void trace_finish(thread_id_t id, int result)
{
/* Finish a trace entry.
*/
btrace_entry *entry;
if (!trace_enabled) return;
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assert(id >= 0 && id < MAX_THREADS + 1);
if ((entry = trace_ptr[id]) == NULL) return;
entry->result = result;
entry->finish_time = trace_gettime();
trace_ptr[id] = NULL;
}