Fix: ensure power of 2 check handles 64-bit size_t entirely
[lttng-modules.git] / lib / ringbuffer / ring_buffer_backend.c
index a9513d1c07e3072fc9e6f6dcd5418554a1af8255..f18ccc1a59c6f1972c5110b64a2341883fa6fe0c 100644 (file)
@@ -155,7 +155,7 @@ pages_error:
 int lib_ring_buffer_backend_create(struct lib_ring_buffer_backend *bufb,
                                   struct channel_backend *chanb, int cpu)
 {
-       const struct lib_ring_buffer_config *config = chanb->config;
+       const struct lib_ring_buffer_config *config = &chanb->config;
 
        bufb->chan = container_of(chanb, struct channel, backend);
        bufb->cpu = cpu;
@@ -187,7 +187,7 @@ void lib_ring_buffer_backend_free(struct lib_ring_buffer_backend *bufb)
 void lib_ring_buffer_backend_reset(struct lib_ring_buffer_backend *bufb)
 {
        struct channel_backend *chanb = &bufb->chan->backend;
-       const struct lib_ring_buffer_config *config = chanb->config;
+       const struct lib_ring_buffer_config *config = &chanb->config;
        unsigned long num_subbuf_alloc;
        unsigned int i;
 
@@ -221,7 +221,7 @@ void lib_ring_buffer_backend_reset(struct lib_ring_buffer_backend *bufb)
 void channel_backend_reset(struct channel_backend *chanb)
 {
        struct channel *chan = container_of(chanb, struct channel, backend);
-       const struct lib_ring_buffer_config *config = chanb->config;
+       const struct lib_ring_buffer_config *config = &chanb->config;
 
        /*
         * Don't reset buf_size, subbuf_size, subbuf_size_order,
@@ -248,7 +248,7 @@ int __cpuinit lib_ring_buffer_cpu_hp_callback(struct notifier_block *nb,
        unsigned int cpu = (unsigned long)hcpu;
        struct channel_backend *chanb = container_of(nb, struct channel_backend,
                                                     cpu_hp_notifier);
-       const struct lib_ring_buffer_config *config = chanb->config;
+       const struct lib_ring_buffer_config *config = &chanb->config;
        struct lib_ring_buffer *buf;
        int ret;
 
@@ -307,18 +307,18 @@ int channel_backend_init(struct channel_backend *chanb,
        if (!name)
                return -EPERM;
 
-       if (!(subbuf_size && num_subbuf))
-               return -EPERM;
-
        /* Check that the subbuffer size is larger than a page. */
        if (subbuf_size < PAGE_SIZE)
                return -EINVAL;
 
        /*
-        * Make sure the number of subbuffers and subbuffer size are power of 2.
+        * Make sure the number of subbuffers and subbuffer size are
+        * power of 2 and nonzero.
         */
-       CHAN_WARN_ON(chanb, hweight32(subbuf_size) != 1);
-       CHAN_WARN_ON(chanb, hweight32(num_subbuf) != 1);
+       if (!subbuf_size || (subbuf_size & (subbuf_size - 1)))
+               return -EINVAL;
+       if (!num_subbuf || (num_subbuf & (num_subbuf - 1)))
+               return -EINVAL;
 
        ret = subbuffer_id_check_index(config, num_subbuf);
        if (ret)
@@ -334,7 +334,7 @@ int channel_backend_init(struct channel_backend *chanb,
                        (config->mode == RING_BUFFER_OVERWRITE) ? 1 : 0;
        chanb->num_subbuf = num_subbuf;
        strlcpy(chanb->name, name, NAME_MAX);
-       chanb->config = config;
+       memcpy(&chanb->config, config, sizeof(chanb->config));
 
        if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
                if (!zalloc_cpumask_var(&chanb->cpumask, GFP_KERNEL))
@@ -421,7 +421,7 @@ free_cpumask:
  */
 void channel_backend_unregister_notifiers(struct channel_backend *chanb)
 {
-       const struct lib_ring_buffer_config *config = chanb->config;
+       const struct lib_ring_buffer_config *config = &chanb->config;
 
        if (config->alloc == RING_BUFFER_ALLOC_PER_CPU)
                unregister_hotcpu_notifier(&chanb->cpu_hp_notifier);
@@ -435,7 +435,7 @@ void channel_backend_unregister_notifiers(struct channel_backend *chanb)
  */
 void channel_backend_free(struct channel_backend *chanb)
 {
-       const struct lib_ring_buffer_config *config = chanb->config;
+       const struct lib_ring_buffer_config *config = &chanb->config;
        unsigned int i;
 
        if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
@@ -469,7 +469,7 @@ void _lib_ring_buffer_write(struct lib_ring_buffer_backend *bufb, size_t offset,
                            const void *src, size_t len, ssize_t pagecpy)
 {
        struct channel_backend *chanb = &bufb->chan->backend;
-       const struct lib_ring_buffer_config *config = chanb->config;
+       const struct lib_ring_buffer_config *config = &chanb->config;
        size_t sbidx, index;
        struct lib_ring_buffer_backend_pages *rpages;
        unsigned long sb_bindex, id;
@@ -501,6 +501,107 @@ void _lib_ring_buffer_write(struct lib_ring_buffer_backend *bufb, size_t offset,
 }
 EXPORT_SYMBOL_GPL(_lib_ring_buffer_write);
 
+
+/**
+ * lib_ring_buffer_memset - write len bytes of c to a ring_buffer buffer.
+ * @bufb : buffer backend
+ * @offset : offset within the buffer
+ * @c : the byte to write
+ * @len : length to write
+ * @pagecpy : page size copied so far
+ */
+void _lib_ring_buffer_memset(struct lib_ring_buffer_backend *bufb,
+                            size_t offset,
+                            int c, size_t len, ssize_t pagecpy)
+{
+       struct channel_backend *chanb = &bufb->chan->backend;
+       const struct lib_ring_buffer_config *config = &chanb->config;
+       size_t sbidx, index;
+       struct lib_ring_buffer_backend_pages *rpages;
+       unsigned long sb_bindex, id;
+
+       do {
+               len -= pagecpy;
+               offset += pagecpy;
+               sbidx = offset >> chanb->subbuf_size_order;
+               index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
+
+               /*
+                * Underlying layer should never ask for writes across
+                * subbuffers.
+                */
+               CHAN_WARN_ON(chanb, offset >= chanb->buf_size);
+
+               pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK));
+               id = bufb->buf_wsb[sbidx].id;
+               sb_bindex = subbuffer_id_get_index(config, id);
+               rpages = bufb->array[sb_bindex];
+               CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE
+                            && subbuffer_id_is_noref(config, id));
+               lib_ring_buffer_do_memset(rpages->p[index].virt
+                                         + (offset & ~PAGE_MASK),
+                                         c, pagecpy);
+       } while (unlikely(len != pagecpy));
+}
+EXPORT_SYMBOL_GPL(_lib_ring_buffer_memset);
+
+
+/**
+ * lib_ring_buffer_copy_from_user - write user data to a ring_buffer buffer.
+ * @bufb : buffer backend
+ * @offset : offset within the buffer
+ * @src : source address
+ * @len : length to write
+ * @pagecpy : page size copied so far
+ *
+ * This function deals with userspace pointers, it should never be called
+ * directly without having the src pointer checked with access_ok()
+ * previously.
+ */
+void _lib_ring_buffer_copy_from_user(struct lib_ring_buffer_backend *bufb,
+                                     size_t offset,
+                                     const void __user *src, size_t len,
+                                     ssize_t pagecpy)
+{
+       struct channel_backend *chanb = &bufb->chan->backend;
+       const struct lib_ring_buffer_config *config = &chanb->config;
+       size_t sbidx, index;
+       struct lib_ring_buffer_backend_pages *rpages;
+       unsigned long sb_bindex, id;
+       int ret;
+
+       do {
+               len -= pagecpy;
+               src += pagecpy;
+               offset += pagecpy;
+               sbidx = offset >> chanb->subbuf_size_order;
+               index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
+
+               /*
+                * Underlying layer should never ask for writes across
+                * subbuffers.
+                */
+               CHAN_WARN_ON(chanb, offset >= chanb->buf_size);
+
+               pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK));
+               id = bufb->buf_wsb[sbidx].id;
+               sb_bindex = subbuffer_id_get_index(config, id);
+               rpages = bufb->array[sb_bindex];
+               CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE
+                               && subbuffer_id_is_noref(config, id));
+               ret = lib_ring_buffer_do_copy_from_user(rpages->p[index].virt
+                                                       + (offset & ~PAGE_MASK),
+                                                       src, pagecpy) != 0;
+               if (ret > 0) {
+                       offset += (pagecpy - ret);
+                       len -= (pagecpy - ret);
+                       _lib_ring_buffer_memset(bufb, offset, 0, len, 0);
+                       break; /* stop copy */
+               }
+       } while (unlikely(len != pagecpy));
+}
+EXPORT_SYMBOL_GPL(_lib_ring_buffer_copy_from_user);
+
 /**
  * lib_ring_buffer_read - read data from ring_buffer_buffer.
  * @bufb : buffer backend
@@ -515,7 +616,7 @@ size_t lib_ring_buffer_read(struct lib_ring_buffer_backend *bufb, size_t offset,
                            void *dest, size_t len)
 {
        struct channel_backend *chanb = &bufb->chan->backend;
-       const struct lib_ring_buffer_config *config = chanb->config;
+       const struct lib_ring_buffer_config *config = &chanb->config;
        size_t index;
        ssize_t pagecpy, orig_len;
        struct lib_ring_buffer_backend_pages *rpages;
@@ -567,7 +668,7 @@ int __lib_ring_buffer_copy_to_user(struct lib_ring_buffer_backend *bufb,
                                   size_t offset, void __user *dest, size_t len)
 {
        struct channel_backend *chanb = &bufb->chan->backend;
-       const struct lib_ring_buffer_config *config = chanb->config;
+       const struct lib_ring_buffer_config *config = &chanb->config;
        size_t index;
        ssize_t pagecpy;
        struct lib_ring_buffer_backend_pages *rpages;
@@ -618,7 +719,7 @@ int lib_ring_buffer_read_cstr(struct lib_ring_buffer_backend *bufb, size_t offse
                              void *dest, size_t len)
 {
        struct channel_backend *chanb = &bufb->chan->backend;
-       const struct lib_ring_buffer_config *config = chanb->config;
+       const struct lib_ring_buffer_config *config = &chanb->config;
        size_t index;
        ssize_t pagecpy, pagelen, strpagelen, orig_offset;
        char *str;
@@ -676,7 +777,7 @@ struct page **lib_ring_buffer_read_get_page(struct lib_ring_buffer_backend *bufb
        size_t index;
        struct lib_ring_buffer_backend_pages *rpages;
        struct channel_backend *chanb = &bufb->chan->backend;
-       const struct lib_ring_buffer_config *config = chanb->config;
+       const struct lib_ring_buffer_config *config = &chanb->config;
        unsigned long sb_bindex, id;
 
        offset &= chanb->buf_size - 1;
@@ -707,7 +808,7 @@ void *lib_ring_buffer_read_offset_address(struct lib_ring_buffer_backend *bufb,
        size_t index;
        struct lib_ring_buffer_backend_pages *rpages;
        struct channel_backend *chanb = &bufb->chan->backend;
-       const struct lib_ring_buffer_config *config = chanb->config;
+       const struct lib_ring_buffer_config *config = &chanb->config;
        unsigned long sb_bindex, id;
 
        offset &= chanb->buf_size - 1;
@@ -737,7 +838,7 @@ void *lib_ring_buffer_offset_address(struct lib_ring_buffer_backend *bufb,
        size_t sbidx, index;
        struct lib_ring_buffer_backend_pages *rpages;
        struct channel_backend *chanb = &bufb->chan->backend;
-       const struct lib_ring_buffer_config *config = chanb->config;
+       const struct lib_ring_buffer_config *config = &chanb->config;
        unsigned long sb_bindex, id;
 
        offset &= chanb->buf_size - 1;
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