1 files changed, 134 insertions, 0 deletions
diff --git a/src/tools/gdbjit.c b/src/tools/gdbjit.c
new file mode 100644
index 00000000..d91c4c05
--- /dev/null
+++ b/src/tools/gdbjit.c
@@ -0,0 +1,134 @@
+#ifdef GDBJIT
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <elf.h>
+#include <errno.h>
+#include "gdbjit.h"
+#include "dynablock.h"
+#include "debug.h"
+
+
+/* GDB JIT Compilation Interface -----------------------------------------------
+ * https://sourceware.org/gdb/current/onlinedocs/gdb.html/JIT-Interface.html
+ */
+
+enum {
+    GDBJIT_NOACTION = 0,
+    GDBJIT_REGISTER,
+    GDBJIT_UNREGISTER
+};
+
+typedef struct gdbjit_code_entry_s {
+    struct gdbjit_code_entry_s* next_entry;
+    struct gdbjit_code_entry_s* prev_entry;
+    const char* symfile_addr;
+    uint64_t symfile_size;
+} gdbjit_code_entry_t;
+
+typedef struct gdbjit_descriptor_s {
+    uint32_t version;
+    uint32_t action_flag;
+    gdbjit_code_entry_t* relevant_entry;
+    gdbjit_code_entry_t* first_entry;
+} gdbjit_descriptor_t;
+
+/* GDB puts a breakpoint in this function. This can't be optimized out. */
+void __attribute__((noinline)) __jit_debug_register_code()
+{
+    asm volatile("" ::: "memory");
+};
+
+/* Make sure to specify the version statically, because the debugger may check
+ * the version before we can set it.
+ */
+gdbjit_descriptor_t __jit_debug_descriptor = { 1, GDBJIT_NOACTION, NULL, NULL };
+
+/* --------------------------------------------------------------------------- */
+
+void GdbJITNewBlock(gdbjit_block_t* block, GDB_CORE_ADDR start, GDB_CORE_ADDR end)
+{
+    if (!block)
+        return;
+
+    memset(block, 0, sizeof(gdbjit_block_t));
+
+    strcpy(block->filename, "/tmp/box64gdbjit-XXXXXX.S");
+    int fd = mkstemps(block->filename, 2);
+    block->file = fdopen(fd, "w");
+
+    block->start = start;
+    block->end = end;
+    block->alloced = block->nlines = 0;
+}
+
+static size_t GdbJITLinesAvailable(gdbjit_block_t* block)
+{
+    if (!block)
+        return 0;
+
+    return block->alloced > block->nlines;
+}
+
+#define GDBJIT_LINES_MAX_PREALLOC 64
+
+static gdbjit_block_t* GdbJITMakeRoom(gdbjit_block_t* block)
+{
+    if (!block) return NULL;
+
+    if (!GdbJITLinesAvailable(block)) {
+        size_t new_size = block->alloced + GDBJIT_LINES_MAX_PREALLOC;
+        block = box_realloc(block, sizeof(gdbjit_block_t) + new_size * sizeof(struct gdb_line_mapping));
+        if (!block) return NULL;
+        block->alloced = new_size;
+    }
+    return block;
+}
+
+gdbjit_block_t* GdbJITBlockAddLine(gdbjit_block_t* block, GDB_CORE_ADDR addr, const char* line)
+{
+    block->nlines++;
+    block = GdbJITMakeRoom(block);
+    if (!block) return NULL;
+
+    block->lines[block->nlines-1].pc = addr;
+    block->lines[block->nlines-1].line = block->nlines;
+    fprintf(block->file, "%s\n", line);
+    fflush(block->file);
+    return block;
+}
+
+void GdbJITBlockReady(gdbjit_block_t* block)
+{
+    if (!block) return;
+
+    if (block->nlines == 0) {
+        fclose(block->file);
+        box_free(block);
+        return;
+    }
+
+    gdbjit_code_entry_t* entry = (gdbjit_code_entry_t*)box_malloc(sizeof(gdbjit_code_entry_t));
+    if (!entry) {
+        fclose(block->file);
+        box_free(block);
+        return;
+    }
+
+    fclose(block->file);
+
+    entry->symfile_addr = (const char*)block;
+    entry->symfile_size = sizeof(gdbjit_block_t) + block->nlines * sizeof(struct gdb_line_mapping);
+
+    if (__jit_debug_descriptor.first_entry) {
+        __jit_debug_descriptor.relevant_entry->next_entry = entry;
+        entry->prev_entry = __jit_debug_descriptor.relevant_entry;
+    } else {
+        __jit_debug_descriptor.first_entry = entry;
+    }
+
+    __jit_debug_descriptor.relevant_entry = entry;
+    __jit_debug_descriptor.action_flag = GDBJIT_REGISTER;
+    __jit_debug_register_code();
+}
+#endif