// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Cell Broadband Engine OProfile Support
 *
 * (C) Copyright IBM Corporation 2006
 *
 * Author: Maynard Johnson <maynardj@us.ibm.com>
 */

/* The purpose of this file is to handle SPU event task switching
 * and to record SPU context information into the OProfile
 * event buffer.
 *
 * Additionally, the spu_sync_buffer function is provided as a helper
 * for recoding actual SPU program counter samples to the event buffer.
 */
#include <linux/dcookies.h>
#include <linux/kref.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/numa.h>
#include <linux/oprofile.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include "pr_util.h"

#define RELEASE_ALL 9999

static DEFINE_SPINLOCK(buffer_lock);
static DEFINE_SPINLOCK(cache_lock);
static int num_spu_nodes;
static int spu_prof_num_nodes;

struct spu_buffer spu_buff[MAX_NUMNODES * SPUS_PER_NODE];
struct delayed_work spu_work;
static unsigned max_spu_buff;

static void spu_buff_add(unsigned long int value, int spu)
{
        /* spu buff is a circular buffer.  Add entries to the
         * head.  Head is the index to store the next value.
         * The buffer is full when there is one available entry
         * in the queue, i.e. head and tail can't be equal.
         * That way we can tell the difference between the
         * buffer being full versus empty.
         *
         *  ASSUMPTION: the buffer_lock is held when this function
         *             is called to lock the buffer, head and tail.
         */
        int full = 1;

        if (spu_buff[spu].head >= spu_buff[spu].tail) {
                if ((spu_buff[spu].head - spu_buff[spu].tail)
                    <  (max_spu_buff - 1))
                        full = 0;

        } else if (spu_buff[spu].tail > spu_buff[spu].head) {
                if ((spu_buff[spu].tail - spu_buff[spu].head)
                    > 1)
                        full = 0;
        }

        if (!full) {
                spu_buff[spu].buff[spu_buff[spu].head] = value;
                spu_buff[spu].head++;

                if (spu_buff[spu].head >= max_spu_buff)
                        spu_buff[spu].head = 0;
        } else {
                /* From the user's perspective make the SPU buffer
                 * size management/overflow look like we are using
                 * per cpu buffers.  The user uses the same
                 * per cpu parameter to adjust the SPU buffer size.
                 * Increment the sample_lost_overflow to inform
                 * the user the buffer size needs to be increased.
                 */
                oprofile_cpu_buffer_inc_smpl_lost();
        }
}

/* This function copies the per SPU buffers to the
 * OProfile kernel buffer.
 */
static void sync_spu_buff(void)
{
        int spu;
        unsigned long flags;
        int curr_head;

        for (spu = 0; spu < num_spu_nodes; spu++) {
                /* In case there was an issue and the buffer didn't
                 * get created skip it.
                 */
                if (spu_buff[spu].buff == NULL)
                        continue;

                /* Hold the lock to make sure the head/tail
                 * doesn't change while spu_buff_add() is
                 * deciding if the buffer is full or not.
                 * Being a little paranoid.
                 */
                spin_lock_irqsave(&buffer_lock, flags);
                curr_head = spu_buff[spu].head;
                spin_unlock_irqrestore(&buffer_lock, flags);

                /* Transfer the current contents to the kernel buffer.
                 * data can still be added to the head of the buffer.
                 */
                oprofile_put_buff(spu_buff[spu].buff,
                                  spu_buff[spu].tail,
                                  curr_head, max_spu_buff);

                spin_lock_irqsave(&buffer_lock, flags);
                spu_buff[spu].tail = curr_head;
                spin_unlock_irqrestore(&buffer_lock, flags);
        }

}

static void wq_sync_spu_buff(struct work_struct *work)
{
        /* move data from spu buffers to kernel buffer */
        sync_spu_buff();

        /* only reschedule if profiling is not done */
        if (spu_prof_running)
                schedule_delayed_work(&spu_work, DEFAULT_TIMER_EXPIRE);
}

/* Container for caching information about an active SPU task. */
struct cached_info {
        struct vma_to_fileoffset_map *map;
        struct spu *the_spu;    /* needed to access pointer to local_store */
        struct kref cache_ref;
};

static struct cached_info *spu_info[MAX_NUMNODES * 8];

static void destroy_cached_info(struct kref *kref)
{
        struct cached_info *info;

        info = container_of(kref, struct cached_info, cache_ref);
        vma_map_free(info->map);
        kfree(info);
        module_put(THIS_MODULE);
}

/* Return the cached_info for the passed SPU number.
 * ATTENTION:  Callers are responsible for obtaining the
 *             cache_lock if needed prior to invoking this function.
 */
static struct cached_info *get_cached_info(struct spu *the_spu, int spu_num)
{
        struct kref *ref;
        struct cached_info *ret_info;

        if (spu_num >= num_spu_nodes) {
                printk(KERN_ERR "SPU_PROF: "
                       "%s, line %d: Invalid index %d into spu info cache\n",
                       __func__, __LINE__, spu_num);
                ret_info = NULL;
                goto out;
        }
        if (!spu_info[spu_num] && the_spu) {
                ref = spu_get_profile_private_kref(the_spu->ctx);
                if (ref) {
                        spu_info[spu_num] = container_of(ref, struct cached_info, cache_ref);
                        kref_get(&spu_info[spu_num]->cache_ref);
                }
        }

        ret_info = spu_info[spu_num];
 out:
        return ret_info;
}


/* Looks for cached info for the passed spu.  If not found, the
 * cached info is created for the passed spu.
 * Returns 0 for success; otherwise, -1 for error.
 */
static int
prepare_cached_spu_info(struct spu *spu, unsigned long objectId)
{
        unsigned long flags;
        struct vma_to_fileoffset_map *new_map;
        int retval = 0;
        struct cached_info *info;

        /* We won't bother getting cache_lock here since
         * don't do anything with the cached_info that's returned.
         */
        info = get_cached_info(spu, spu->number);

        if (info) {
                pr_debug("Found cached SPU info.\n");
                goto out;
        }

        /* Create cached_info and set spu_info[spu->number] to point to it.
         * spu->number is a system-wide value, not a per-node value.
         */
        info = kzalloc(sizeof(*info), GFP_KERNEL);
        if (!info) {
                printk(KERN_ERR "SPU_PROF: "
                       "%s, line %d: create vma_map failed\n",
                       __func__, __LINE__);
                retval = -ENOMEM;
                goto err_alloc;
        }
        new_map = create_vma_map(spu, objectId);
        if (!new_map) {
                printk(KERN_ERR "SPU_PROF: "
                       "%s, line %d: create vma_map failed\n",
                       __func__, __LINE__);
                retval = -ENOMEM;
                goto err_alloc;
        }

        pr_debug("Created vma_map\n");
        info->map = new_map;
        info->the_spu = spu;
        kref_init(&info->cache_ref);
        spin_lock_irqsave(&cache_lock, flags);
        spu_info[spu->number] = info;
        /* Increment count before passing off ref to SPUFS. */
        kref_get(&info->cache_ref);

        /* We increment the module refcount here since SPUFS is
         * responsible for the final destruction of the cached_info,
         * and it must be able to access the destroy_cached_info()
         * function defined in the OProfile module.  We decrement
         * the module refcount in destroy_cached_info.
         */
        try_module_get(THIS_MODULE);
        spu_set_profile_private_kref(spu->ctx, &info->cache_ref,
                                destroy_cached_info);
        spin_unlock_irqrestore(&cache_lock, flags);
        goto out;

err_alloc:
        kfree(info);
out:
        return retval;
}

/*
 * NOTE:  The caller is responsible for locking the
 *        cache_lock prior to calling this function.
 */
static int release_cached_info(int spu_index)
{
        int index, end;

        if (spu_index == RELEASE_ALL) {
                end = num_spu_nodes;
                index = 0;
        } else {
                if (spu_index >= num_spu_nodes) {
                        printk(KERN_ERR "SPU_PROF: "
                                "%s, line %d: "
                                "Invalid index %d into spu info cache\n",
                                __func__, __LINE__, spu_index);
                        goto out;
                }
                end = spu_index + 1;
                index = spu_index;
        }
        for (; index < end; index++) {
                if (spu_info[index]) {
                        kref_put(&spu_info[index]->cache_ref,
                                 destroy_cached_info);
                        spu_info[index] = NULL;
                }
        }

out:
        return 0;
}

/* The source code for fast_get_dcookie was "borrowed"
 * from drivers/oprofile/buffer_sync.c.
 */

/* Optimisation. We can manage without taking the dcookie sem
 * because we cannot reach this code without at least one
 * dcookie user still being registered (namely, the reader
 * of the event buffer).
 */
static inline unsigned long fast_get_dcookie(const struct path *path)
{
        unsigned long cookie;

        if (path->dentry->d_flags & DCACHE_COOKIE)
                return (unsigned long)path->dentry;
        get_dcookie(path, &cookie);
        return cookie;
}

/* Look up the dcookie for the task's mm->exe_file,
 * which corresponds loosely to "application name". Also, determine
 * the offset for the SPU ELF object.  If computed offset is
 * non-zero, it implies an embedded SPU object; otherwise, it's a
 * separate SPU binary, in which case we retrieve it's dcookie.
 * For the embedded case, we must determine if SPU ELF is embedded
 * in the executable application or another file (i.e., shared lib).
 * If embedded in a shared lib, we must get the dcookie and return
 * that to the caller.
 */
static unsigned long
get_exec_dcookie_and_offset(struct spu *spu, unsigned int *offsetp,
                            unsigned long *spu_bin_dcookie,
                            unsigned long spu_ref)
{
        unsigned long app_cookie = 0;
        unsigned int my_offset = 0;
        struct vm_area_struct *vma;
        struct file *exe_file;
        struct mm_struct *mm = spu->mm;

        if (!mm)
                goto out;

        exe_file = get_mm_exe_file(mm);
        if (exe_file) {
                app_cookie = fast_get_dcookie(&exe_file->f_path);
                pr_debug("got dcookie for %pD\n", exe_file);
                fput(exe_file);
        }

        down_read(&mm->mmap_sem);
        for (vma = mm->mmap; vma; vma = vma->vm_next) {
                if (vma->vm_start > spu_ref || vma->vm_end <= spu_ref)
                        continue;
                my_offset = spu_ref - vma->vm_start;
                if (!vma->vm_file)
                        goto fail_no_image_cookie;

                pr_debug("Found spu ELF at %X(object-id:%lx) for file %pD\n",
                         my_offset, spu_ref, vma->vm_file);
                *offsetp = my_offset;
                break;
        }

        *spu_bin_dcookie = fast_get_dcookie(&vma->vm_file->f_path);
        pr_debug("got dcookie for %pD\n", vma->vm_file);

        up_read(&mm->mmap_sem);

out:
        return app_cookie;

fail_no_image_cookie:
        up_read(&mm->mmap_sem);

        printk(KERN_ERR "SPU_PROF: "
                "%s, line %d: Cannot find dcookie for SPU binary\n",
                __func__, __LINE__);
        goto out;
}



/* This function finds or creates cached context information for the
 * passed SPU and records SPU context information into the OProfile
 * event buffer.
 */
static int process_context_switch(struct spu *spu, unsigned long objectId)
{
        unsigned long flags;
        int retval;
        unsigned int offset = 0;
        unsigned long spu_cookie = 0, app_dcookie;

        retval = prepare_cached_spu_info(spu, objectId);
        if (retval)
                goto out;

        /* Get dcookie first because a mutex_lock is taken in that
         * code path, so interrupts must not be disabled.
         */
        app_dcookie = get_exec_dcookie_and_offset(spu, &offset, &spu_cookie, objectId);
        if (!app_dcookie || !spu_cookie) {
                retval  = -ENOENT;
                goto out;
        }

        /* Record context info in event buffer */
        spin_lock_irqsave(&buffer_lock, flags);
        spu_buff_add(ESCAPE_CODE, spu->number);
        spu_buff_add(SPU_CTX_SWITCH_CODE, spu->number);
        spu_buff_add(spu->number, spu->number);
        spu_buff_add(spu->pid, spu->number);
        spu_buff_add(spu->tgid, spu->number);
        spu_buff_add(app_dcookie, spu->number);
        spu_buff_add(spu_cookie, spu->number);
        spu_buff_add(offset, spu->number);

        /* Set flag to indicate SPU PC data can now be written out.  If
         * the SPU program counter data is seen before an SPU context
         * record is seen, the postprocessing will fail.
         */
        spu_buff[spu->number].ctx_sw_seen = 1;

        spin_unlock_irqrestore(&buffer_lock, flags);
        smp_wmb();      /* insure spu event buffer updates are written */
                        /* don't want entries intermingled... */
out:
        return retval;
}

/*
 * This function is invoked on either a bind_context or unbind_context.
 * If called for an unbind_context, the val arg is 0; otherwise,
 * it is the object-id value for the spu context.
 * The data arg is of type 'struct spu *'.
 */
static int spu_active_notify(struct notifier_block *self, unsigned long val,
                                void *data)
{
        int retval;
        unsigned long flags;
        struct spu *the_spu = data;

        pr_debug("SPU event notification arrived\n");
        if (!val) {
                spin_lock_irqsave(&cache_lock, flags);
                retval = release_cached_info(the_spu->number);
                spin_unlock_irqrestore(&cache_lock, flags);
        } else {
                retval = process_context_switch(the_spu, val);
        }
        return retval;
}

static struct notifier_block spu_active = {
        .notifier_call = spu_active_notify,
};

static int number_of_online_nodes(void)
{
        u32 cpu; u32 tmp;
        int nodes = 0;
        for_each_online_cpu(cpu) {
                tmp = cbe_cpu_to_node(cpu) + 1;
                if (tmp > nodes)
                        nodes++;
        }
        return nodes;
}

static int oprofile_spu_buff_create(void)
{
        int spu;

        max_spu_buff = oprofile_get_cpu_buffer_size();

        for (spu = 0; spu < num_spu_nodes; spu++) {
                /* create circular buffers to store the data in.
                 * use locks to manage accessing the buffers
                 */
                spu_buff[spu].head = 0;
                spu_buff[spu].tail = 0;

                /*
                 * Create a buffer for each SPU.  Can't reliably
                 * create a single buffer for all spus due to not
                 * enough contiguous kernel memory.
                 */

                spu_buff[spu].buff = kzalloc((max_spu_buff
                                              * sizeof(unsigned long)),
                                             GFP_KERNEL);

                if (!spu_buff[spu].buff) {
                        printk(KERN_ERR "SPU_PROF: "
                               "%s, line %d:  oprofile_spu_buff_create "
                       "failed to allocate spu buffer %d.\n",
                               __func__, __LINE__, spu);

                        /* release the spu buffers that have been allocated */
                        while (spu >= 0) {
                                kfree(spu_buff[spu].buff);
                                spu_buff[spu].buff = 0;
                                spu--;
                        }
                        return -ENOMEM;
                }
        }
        return 0;
}

/* The main purpose of this function is to synchronize
 * OProfile with SPUFS by registering to be notified of
 * SPU task switches.
 *
 * NOTE: When profiling SPUs, we must ensure that only
 * spu_sync_start is invoked and not the generic sync_start
 * in drivers/oprofile/oprof.c.  A return value of
 * SKIP_GENERIC_SYNC or SYNC_START_ERROR will
 * accomplish this.
 */
int spu_sync_start(void)
{
        int spu;
        int ret = SKIP_GENERIC_SYNC;
        int register_ret;
        unsigned long flags = 0;

        spu_prof_num_nodes = number_of_online_nodes();
        num_spu_nodes = spu_prof_num_nodes * 8;
        INIT_DELAYED_WORK(&spu_work, wq_sync_spu_buff);

        /* create buffer for storing the SPU data to put in
         * the kernel buffer.
         */
        ret = oprofile_spu_buff_create();
        if (ret)
                goto out;

        spin_lock_irqsave(&buffer_lock, flags);
        for (spu = 0; spu < num_spu_nodes; spu++) {
                spu_buff_add(ESCAPE_CODE, spu);
                spu_buff_add(SPU_PROFILING_CODE, spu);
                spu_buff_add(num_spu_nodes, spu);
        }
        spin_unlock_irqrestore(&buffer_lock, flags);

        for (spu = 0; spu < num_spu_nodes; spu++) {
                spu_buff[spu].ctx_sw_seen = 0;
                spu_buff[spu].last_guard_val = 0;
        }

        /* Register for SPU events  */
        register_ret = spu_switch_event_register(&spu_active);
        if (register_ret) {
                ret = SYNC_START_ERROR;
                goto out;
        }

        pr_debug("spu_sync_start -- running.\n");
out:
        return ret;
}

/* Record SPU program counter samples to the oprofile event buffer. */
void spu_sync_buffer(int spu_num, unsigned int *samples,
                     int num_samples)
{
        unsigned long long file_offset;
        unsigned long flags;
        int i;
        struct vma_to_fileoffset_map *map;
        struct spu *the_spu;
        unsigned long long spu_num_ll = spu_num;
        unsigned long long spu_num_shifted = spu_num_ll << 32;
        struct cached_info *c_info;

        /* We need to obtain the cache_lock here because it's
         * possible that after getting the cached_info, the SPU job
         * corresponding to this cached_info may end, thus resulting
         * in the destruction of the cached_info.
         */
        spin_lock_irqsave(&cache_lock, flags);
        c_info = get_cached_info(NULL, spu_num);
        if (!c_info) {
                /* This legitimately happens when the SPU task ends before all
                 * samples are recorded.
                 * No big deal -- so we just drop a few samples.
                 */
                pr_debug("SPU_PROF: No cached SPU contex "
                          "for SPU #%d. Dropping samples.\n", spu_num);
                goto out;
        }

        map = c_info->map;
        the_spu = c_info->the_spu;
        spin_lock(&buffer_lock);
        for (i = 0; i < num_samples; i++) {
                unsigned int sample = *(samples+i);
                int grd_val = 0;
                file_offset = 0;
                if (sample == 0)
                        continue;
                file_offset = vma_map_lookup( map, sample, the_spu, &grd_val);

                /* If overlays are used by this SPU application, the guard
                 * value is non-zero, indicating which overlay section is in
                 * use.  We need to discard samples taken during the time
                 * period which an overlay occurs (i.e., guard value changes).
                 */
                if (grd_val && grd_val != spu_buff[spu_num].last_guard_val) {
                        spu_buff[spu_num].last_guard_val = grd_val;
                        /* Drop the rest of the samples. */
                        break;
                }

                /* We must ensure that the SPU context switch has been written
                 * out before samples for the SPU.  Otherwise, the SPU context
                 * information is not available and the postprocessing of the
                 * SPU PC will fail with no available anonymous map information.
                 */
                if (spu_buff[spu_num].ctx_sw_seen)
                        spu_buff_add((file_offset | spu_num_shifted),
                                         spu_num);
        }
        spin_unlock(&buffer_lock);
out:
        spin_unlock_irqrestore(&cache_lock, flags);
}


int spu_sync_stop(void)
{
        unsigned long flags = 0;
        int ret;
        int k;

        ret = spu_switch_event_unregister(&spu_active);

        if (ret)
                printk(KERN_ERR "SPU_PROF: "
                       "%s, line %d: spu_switch_event_unregister "      \
                       "returned %d\n",
                       __func__, __LINE__, ret);

        /* flush any remaining data in the per SPU buffers */
        sync_spu_buff();

        spin_lock_irqsave(&cache_lock, flags);
        ret = release_cached_info(RELEASE_ALL);
        spin_unlock_irqrestore(&cache_lock, flags);

        /* remove scheduled work queue item rather then waiting
         * for every queued entry to execute.  Then flush pending
         * system wide buffer to event buffer.
         */
        cancel_delayed_work(&spu_work);

        for (k = 0; k < num_spu_nodes; k++) {
                spu_buff[k].ctx_sw_seen = 0;

                /*
                 * spu_sys_buff will be null if there was a problem
                 * allocating the buffer.  Only delete if it exists.
                 */
                kfree(spu_buff[k].buff);
                spu_buff[k].buff = 0;
        }
        pr_debug("spu_sync_stop -- done.\n");
        return ret;
}