Fix: Filter bytecode alloc buffer size must be a power of 2
[lttng-tools.git] / src / lib / lttng-ctl / filter / filter-visitor-generate-bytecode.c
index 36d35c558727e6df654a55b3bebc1bee4fb069de..71da21c8a5108a8f0114aa9389c16d92bc54240a 100644 (file)
@@ -38,6 +38,45 @@ static
 int recursive_visit_gen_bytecode(struct filter_parser_ctx *ctx,
                struct ir_op *node);
 
+static inline int fls(unsigned int x)
+{
+       int r = 32;
+
+       if (!x)
+               return 0;
+       if (!(x & 0xFFFF0000U)) {
+               x <<= 16;
+               r -= 16;
+       }
+       if (!(x & 0xFF000000U)) {
+               x <<= 8;
+               r -= 8;
+       }
+       if (!(x & 0xF0000000U)) {
+               x <<= 4;
+               r -= 4;
+       }
+       if (!(x & 0xC0000000U)) {
+               x <<= 2;
+               r -= 2;
+       }
+       if (!(x & 0x80000000U)) {
+               x <<= 1;
+               r -= 1;
+       }
+       return r;
+}
+
+static inline int get_count_order(unsigned int count)
+{
+       int order;
+
+       order = fls(count) - 1;
+       if (count & (count - 1))
+               order++;
+       return order;
+}
+
 static
 int bytecode_init(struct lttng_filter_bytecode_alloc **fb)
 {
@@ -58,7 +97,7 @@ int32_t bytecode_reserve(struct lttng_filter_bytecode_alloc **fb, uint32_t align
 
        if ((*fb)->b.len + padding + len > (*fb)->alloc_len) {
                uint32_t new_len =
-                       max_t(uint32_t, (*fb)->b.len + padding + len,
+                       max_t(uint32_t, 1U << get_count_order((*fb)->b.len + padding + len),
                                (*fb)->alloc_len << 1);
                uint32_t old_len = (*fb)->alloc_len;
 
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