On 08.10.2016 12:58, Marek Olšák wrote:
From: Marek Olšák <[email protected]>
It would be useful to hook this up with Valgrind and address sanitizer.
Some drivers already do that; basically, there are macros
VALGRIND_MAKE_MEM_{NOACCESS, UNDEFINED, DEFINED} in valgrind/memcheck.h,
and similarly address sanitizer has
__asan_{poison,unpoison}_memory_region intrinsics.
The linear_size_chunks can serve as red zones helping to catch array
overflows.
This doesn't necessarily have to be in the same commit, but it would be
good to do it soon.
---
src/util/ralloc.c | 355 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
src/util/ralloc.h | 84 ++++++++++++-
2 files changed, 435 insertions(+), 4 deletions(-)
diff --git a/src/util/ralloc.c b/src/util/ralloc.c
index bf21ac3..a8e660f 100644
--- a/src/util/ralloc.c
+++ b/src/util/ralloc.c
@@ -522,10 +522,365 @@ ralloc_vasprintf_rewrite_tail(char **str, size_t *start,
const char *fmt,
ptr = resize(*str, *start + new_length + 1);
if (unlikely(ptr == NULL))
return false;
vsnprintf(ptr + *start, new_length + 1, fmt, args);
*str = ptr;
*start += new_length;
return true;
}
+
+/***************************************************************************
+ * Linear allocator for short-lived allocations.
+ ***************************************************************************
+ *
+ * The allocator consists of a parent node (2K buffer), which requires
+ * a ralloc parent, and child nodes (allocations). Child nodes can't be freed
+ * directly, because the parent doesn't track them. You have to release
+ * the parent node in order to release all its children.
+ *
+ * The allocator uses a fixed-sized buffer with a monotonically increasing
+ * offset after each allocation. If the buffer is all used, another buffer
+ * is allocated, sharing the same ralloc parent, so all buffers are at
+ * the same level in the ralloc hierarchy.
+ *
+ * The linear parent node is always the first buffer and keeps track of all
+ * other buffers.
+ */
+
+#define ALIGN(x, y) (((x) + (y) - 1) & ~((y) - 1))
Please rename this to ALIGN_POT or similar.
+#define MIN_LINEAR_BUFSIZE 2048
+#define LMAGIC 0x87b9c7d3
+
+struct linear_header {
+#ifdef DEBUG
+ unsigned magic; /* for debugging */
+#endif
+ unsigned offset; /* points to the first unused byte in the buffer */
+ unsigned size; /* size of the buffer */
+ void *ralloc_parent; /* new buffers will use this */
+ struct linear_header *next; /* next buffer if we have more */
+ struct linear_header *latest; /* the only buffer that has free space */
+
+ /* After this structure, the buffer begins.
+ * Each suballocation consists of linear_size_chunk as its header followed
+ * by the suballocation, so it goes:
+ *
+ * - linear_size_chunk
+ * - allocated space
+ * - linear_size_chunk
+ * - allocated space
+ * etc.
+ *
+ * linear_size_chunk is only needed by linear_realloc.
+ */
+};
+
+struct linear_size_chunk {
+ unsigned size; /* for realloc */
+ unsigned _padding;
+};
+
+typedef struct linear_header linear_header;
+typedef struct linear_size_chunk linear_size_chunk;
+
+#define LINEAR_PARENT_TO_HEADER(parent) \
+ (linear_header*) \
+ ((char*)(parent) - sizeof(linear_size_chunk) - sizeof(linear_header))
+
+/* Allocate the linear buffer with its header. */
+static linear_header *
+create_linear_node(void *ralloc_ctx, unsigned min_size)
+{
+ linear_header *node;
+
+ min_size += sizeof(linear_size_chunk);
+
+ if (likely(min_size < MIN_LINEAR_BUFSIZE))
+ min_size = MIN_LINEAR_BUFSIZE;
+
+ node = ralloc_size(ralloc_ctx, sizeof(linear_header) + min_size);
+ if (unlikely(!node))
+ return NULL;
+
+#ifdef DEBUG
+ node->magic = LMAGIC;
+#endif
+ node->offset = 0;
+ node->size = min_size;
+ node->ralloc_parent = ralloc_ctx;
+ node->next = NULL;
+ node->latest = node;
+ return node;
+}
+
+void *
+linear_alloc_child(void *parent, unsigned size)
+{
+ linear_header *first = LINEAR_PARENT_TO_HEADER(parent);
+ linear_header *latest = first->latest;
+ linear_header *new_node;
+ linear_size_chunk *ptr;
+ unsigned full_size;
+
+ assert(first->magic == LMAGIC);
+ assert(!latest->next);
+
+ size = ALIGN(size, 8);
sizeof(size_t) instead of 8? In a similar vein, you could use size_t in
linear_size_chunk.
+ full_size = sizeof(linear_size_chunk) + size;
+
+ if (likely(latest->offset + full_size <= latest->size)) {
+alloc:
Please avoid the goto by inverting the logic here.
+ ptr = (linear_size_chunk *)((char*)&latest[1] + latest->offset);
+ ptr->size = size;
+ latest->offset += full_size;
+ return &ptr[1];
+ }
+
+ /* allocate a new node */
+ new_node = create_linear_node(latest->ralloc_parent, size);
+ if (unlikely(!new_node))
+ return NULL;
+
+ first->latest = new_node;
+ latest->latest = new_node;
+ latest->next = new_node;
+ latest = new_node;
+
+ goto alloc;
+}
+
+void *
+linear_alloc_parent(void *ralloc_ctx, unsigned size)
+{
+ linear_header *node;
+
+ if (unlikely(!ralloc_ctx))
+ return NULL;
+
+ size = ALIGN(size, 8);
+
+ node = create_linear_node(ralloc_ctx, size);
+ if (unlikely(!node))
+ return NULL;
+
+ return linear_alloc_child((char*)node +
+ sizeof(linear_header) +
+ sizeof(linear_size_chunk), size);
+}
+
+void *
+linear_zalloc_child(void *parent, unsigned size)
+{
+ void *ptr = linear_alloc_child(parent, size);
+
+ if (likely(ptr))
+ memset(ptr, 0, size);
+ return ptr;
+}
+
+void *
+linear_zalloc_parent(void *parent, unsigned size)
+{
+ void *ptr = linear_alloc_parent(parent, size);
+
+ if (likely(ptr))
+ memset(ptr, 0, size);
+ return ptr;
+}
+
+void
+linear_free_parent(void *ptr)
+{
+ linear_header *node;
+
+ if (unlikely(!ptr))
+ return;
+
+ node = LINEAR_PARENT_TO_HEADER(ptr);
+ assert(node->magic == LMAGIC);
+
+ while (node) {
+ void *ptr = node;
+
+ node = node->next;
+ ralloc_free(ptr);
+ }
+}
+
+void
+ralloc_steal_linear_parent(void *new_ralloc_ctx, void *ptr)
+{
+ linear_header *node;
+
+ if (unlikely(!ptr))
+ return;
+
+ node = LINEAR_PARENT_TO_HEADER(ptr);
+ assert(node->magic == LMAGIC);
+
+ while (node) {
+ ralloc_steal(new_ralloc_ctx, node);
+ node->ralloc_parent = new_ralloc_ctx;
+ node = node->next;
+ }
+}
+
+void *
+ralloc_parent_of_linear_parent(void *ptr)
+{
+ linear_header *node = LINEAR_PARENT_TO_HEADER(ptr);
+ assert(node->magic == LMAGIC);
+ return node->ralloc_parent;
+}
+
+void *
+linear_realloc(void *parent, void *old, unsigned new_size)
+{
+ size_t old_size = 0;
+ ralloc_header *new_ptr;
+
+ new_ptr = linear_alloc_child(parent, new_size);
+
+ if (unlikely(!old))
+ return new_ptr;
+
+ old_size = ((linear_size_chunk*)old)[-1].size;
+
+ if (likely(new_ptr && old_size))
+ memcpy(new_ptr, old, old_size > new_size ? new_size : old_size);
Use MIN2.
Nicolai
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