WIP - add tentative libunwind.h

libelfunwind/README.md

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+# libelfunwind
+
+Reproduces the interface of libunwind, and exports a `libunwind.so` binary, so
+that changing `LD_LIBRARY_PATH` makes it possible to use `dwarf-assembly`
+instead of `dwarf` as an unwinding process in eg. `perf`.
+
+## `perf` currently used libunwind features
+
+```
+  # Types
+  unw_accessors_t
+  unw_word_t
+  unw_regnum_t
+  unw_proc_info_t
+  unw_fpreg_t
+  unw_dyn_info_t
+  unw_addr_space_t
+  unw_cursor_t
+
+  # Functions
+  unw_create_addr_space
+  unw_destroy_addr_space
+  unw_flush_cache
+  unw_get_reg
+  unw_init_remote
+  unw_is_signal_frame
+  unw_set_caching_policy
+  unw_step
+```

libelfunwind/libunwind.h

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+/**
+ * This is a custom version of libunwind making use of dwarf-assembly and its
+ * eh_elfs as an unwinding procedure.
+ **/
+
+#include <stdint.h>
+
+struct unw_context_t {};
+struct unw_cursor_t {};
+
+typedef int unw_regnum_t;
+typedef uint64_t unw_word_t;
+
+
+int unw_getcontext(unw_context_t *);
+int unw_init_local(unw_cursor_t *, unw_context_t *);
+// int unw_init_remote(unw_cursor_t *, unw_addr_space_t, void *);
+int unw_step(unw_cursor_t *);
+int unw_get_reg(unw_cursor_t *, unw_regnum_t, unw_word_t *);
+int unw_get_fpreg(unw_cursor_t *, unw_regnum_t, unw_fpreg_t *);
+int unw_set_reg(unw_cursor_t *, unw_regnum_t, unw_word_t);
+int unw_set_fpreg(unw_cursor_t *, unw_regnum_t, unw_fpreg_t);
+int unw_resume(unw_cursor_t *);
+
+unw_addr_space_t unw_local_addr_space;
+unw_addr_space_t unw_create_addr_space(unw_accessors_t, int);
+void unw_destroy_addr_space(unw_addr_space_t);
+unw_accessors_t unw_get_accessors(unw_addr_space_t);
+void unw_flush_cache(unw_addr_space_t, unw_word_t, unw_word_t);
+int unw_set_caching_policy(unw_addr_space_t, unw_caching_policy_t);
+
+const char *unw_regname(unw_regnum_t);
+int unw_get_proc_info(unw_cursor_t *, unw_proc_info_t *);
+int unw_get_save_loc(unw_cursor_t *, int, unw_save_loc_t *);
+int unw_is_fpreg(unw_regnum_t);
+int unw_is_signal_frame(unw_cursor_t *);
+int unw_get_proc_name(unw_cursor_t *, char *, size_t, unw_word_t *);
+
+void _U_dyn_register(unw_dyn_info_t *);
+void _U_dyn_cancel(unw_dyn_info_t *);