Fix: use unaligned pointer accesses for lttng_inline_memcpy

[lttng-ust.git] / src / common / ringbuffer / backend_internal.h

diff --git a/src/common/ringbuffer/backend_internal.h b/src/common/ringbuffer/backend_internal.h
index 9ce9d1405662a150a55737c54746d208115ed2b2..a3303b72c3a86de752ce1f609f48467905c8f286 100644 (file)
--- a/src/common/ringbuffer/backend_internal.h
+++ b/src/common/ringbuffer/backend_internal.h
@@ -205,7 +205,7 @@ int subbuffer_id_check_index(const struct lttng_ust_ring_buffer_config *config,
 
 static inline
 int lib_ring_buffer_backend_get_pages(const struct lttng_ust_ring_buffer_config *config,
-                       struct lttng_ust_ring_buffer_ctx *ctx,
+                       const struct lttng_ust_ring_buffer_ctx *ctx,
                        struct lttng_ust_ring_buffer_backend_pages **backend_pages)
 {
        struct lttng_ust_ring_buffer_ctx_private *ctx_private = ctx->priv;
@@ -244,7 +244,7 @@ static inline
 struct lttng_ust_ring_buffer_backend_pages *
        lib_ring_buffer_get_backend_pages_from_ctx(
                const struct lttng_ust_ring_buffer_config *config __attribute__((unused)),
-               struct lttng_ust_ring_buffer_ctx *ctx)
+               const struct lttng_ust_ring_buffer_ctx *ctx)
 {
        return ctx->priv->backend_pages;
 }
@@ -256,9 +256,7 @@ struct lttng_ust_ring_buffer_backend_pages *
 #ifdef LTTNG_RING_BUFFER_COUNT_EVENTS
 static inline
 void subbuffer_count_record(const struct lttng_ust_ring_buffer_config *config,
-                           const struct lttng_ust_ring_buffer_ctx *ctx,
-                           struct lttng_ust_ring_buffer_backend *bufb,
-                           unsigned long idx, struct lttng_ust_shm_handle *handle)
+                           const struct lttng_ust_ring_buffer_ctx *ctx)
 {
        struct lttng_ust_ring_buffer_backend_pages *backend_pages;
 
@@ -272,10 +270,7 @@ void subbuffer_count_record(const struct lttng_ust_ring_buffer_config *config,
 #else /* LTTNG_RING_BUFFER_COUNT_EVENTS */
 static inline
 void subbuffer_count_record(const struct lttng_ust_ring_buffer_config *config __attribute__((unused)),
-               const struct lttng_ust_ring_buffer_ctx *ctx __attribute__((unused)),
-               struct lttng_ust_ring_buffer_backend *bufb __attribute__((unused)),
-               unsigned long idx __attribute__((unused)),
-               struct lttng_ust_shm_handle *handle __attribute__((unused)))
+               const struct lttng_ust_ring_buffer_ctx *ctx __attribute__((unused)))
 {
 }
 #endif /* #else LTTNG_RING_BUFFER_COUNT_EVENTS */
@@ -600,6 +595,21 @@ int update_read_sb_index(const struct lttng_ust_ring_buffer_config *config,
 #define inline_memcpy(dest, src, n)    memcpy(dest, src, n)
 #endif
 
+#define LOAD_UNALIGNED_INT(type, p) \
+       ({ \
+               struct packed_struct { type __v; } __attribute__((packed)); \
+               (((const struct packed_struct *) (p))->__v); \
+       })
+
+#define STORE_UNALIGNED_INT(type, p, v)        \
+       do { \
+               struct packed_struct { type __v; } __attribute__((packed)); \
+               ((struct packed_struct *) (p))->__v = (v); \
+       } while (0)
+
+/*
+ * Copy from src into dest, assuming unaligned src and dest.
+ */
 static inline
 void lttng_inline_memcpy(void *dest, const void *src,
                unsigned long len)
@@ -613,13 +623,13 @@ void lttng_inline_memcpy(void *dest, const void *src,
                *(uint8_t *) dest = *(const uint8_t *) src;
                break;
        case 2:
-               *(uint16_t *) dest = *(const uint16_t *) src;
+               STORE_UNALIGNED_INT(uint16_t, dest, LOAD_UNALIGNED_INT(uint16_t, src));
                break;
        case 4:
-               *(uint32_t *) dest = *(const uint32_t *) src;
+               STORE_UNALIGNED_INT(uint32_t, dest, LOAD_UNALIGNED_INT(uint32_t, src));
                break;
        case 8:
-               *(uint64_t *) dest = *(const uint64_t *) src;
+               STORE_UNALIGNED_INT(uint64_t, dest, LOAD_UNALIGNED_INT(uint64_t, src));
                break;
        default:
                inline_memcpy(dest, src, len);