1 //===--------------------- UnwindLevel1-gcc-ext.c -------------------------===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
8 // Implements gcc extensions to the C++ ABI Exception Handling Level 1.
10 //===----------------------------------------------------------------------===//
20 #include "libunwind_ext.h"
21 #include "libunwind.h"
22 #include "Unwind-EHABI.h"
25 #if defined(_LIBUNWIND_BUILD_ZERO_COST_APIS)
27 #if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
28 #define private_1 private_[0]
31 /// Called by __cxa_rethrow().
32 _LIBUNWIND_EXPORT _Unwind_Reason_Code
33 _Unwind_Resume_or_Rethrow(_Unwind_Exception *exception_object) {
34 #if defined(_LIBUNWIND_ARM_EHABI)
35 _LIBUNWIND_TRACE_API("_Unwind_Resume_or_Rethrow(ex_obj=%p), private_1=%ld",
36 (void *)exception_object,
37 (long)exception_object->unwinder_cache.reserved1);
39 _LIBUNWIND_TRACE_API("_Unwind_Resume_or_Rethrow(ex_obj=%p), private_1=%" PRIdPTR,
40 (void *)exception_object,
41 (intptr_t)exception_object->private_1);
44 #if defined(_LIBUNWIND_ARM_EHABI)
45 // _Unwind_RaiseException on EHABI will always set the reserved1 field to 0,
46 // which is in the same position as private_1 below.
47 return _Unwind_RaiseException(exception_object);
49 // If this is non-forced and a stopping place was found, then this is a
51 // Call _Unwind_RaiseException() as if this was a new exception
52 if (exception_object->private_1 == 0) {
53 return _Unwind_RaiseException(exception_object);
54 // Will return if there is no catch clause, so that __cxa_rethrow can call
58 // Call through to _Unwind_Resume() which distiguishes between forced and
59 // regular exceptions.
60 _Unwind_Resume(exception_object);
61 _LIBUNWIND_ABORT("_Unwind_Resume_or_Rethrow() called _Unwind_RaiseException()"
62 " which unexpectedly returned");
67 /// Called by personality handler during phase 2 to get base address for data
68 /// relative encodings.
69 _LIBUNWIND_EXPORT uintptr_t
70 _Unwind_GetDataRelBase(struct _Unwind_Context *context) {
72 _LIBUNWIND_TRACE_API("_Unwind_GetDataRelBase(context=%p)", (void *)context);
73 _LIBUNWIND_ABORT("_Unwind_GetDataRelBase() not implemented");
77 /// Called by personality handler during phase 2 to get base address for text
78 /// relative encodings.
79 _LIBUNWIND_EXPORT uintptr_t
80 _Unwind_GetTextRelBase(struct _Unwind_Context *context) {
82 _LIBUNWIND_TRACE_API("_Unwind_GetTextRelBase(context=%p)", (void *)context);
83 _LIBUNWIND_ABORT("_Unwind_GetTextRelBase() not implemented");
87 /// Scans unwind information to find the function that contains the
88 /// specified code address "pc".
89 _LIBUNWIND_EXPORT void *_Unwind_FindEnclosingFunction(void *pc) {
90 _LIBUNWIND_TRACE_API("_Unwind_FindEnclosingFunction(pc=%p)", pc);
91 // This is slow, but works.
92 // We create an unwind cursor then alter the IP to be pc
96 __unw_getcontext(&uc);
97 __unw_init_local(&cursor, &uc);
98 __unw_set_reg(&cursor, UNW_REG_IP, (unw_word_t)(intptr_t)pc);
99 if (__unw_get_proc_info(&cursor, &info) == UNW_ESUCCESS)
100 return (void *)(intptr_t) info.start_ip;
105 /// Walk every frame and call trace function at each one. If trace function
106 /// returns anything other than _URC_NO_REASON, then walk is terminated.
107 _LIBUNWIND_EXPORT _Unwind_Reason_Code
108 _Unwind_Backtrace(_Unwind_Trace_Fn callback, void *ref) {
111 __unw_getcontext(&uc);
112 __unw_init_local(&cursor, &uc);
114 _LIBUNWIND_TRACE_API("_Unwind_Backtrace(callback=%p)",
115 (void *)(uintptr_t)callback);
117 #if defined(_LIBUNWIND_ARM_EHABI)
118 // Create a mock exception object for force unwinding.
119 _Unwind_Exception ex;
120 memset(&ex, '\0', sizeof(ex));
121 ex.exception_class = 0x434C4E47554E5700; // CLNGUNW\0
126 _Unwind_Reason_Code result;
128 #if !defined(_LIBUNWIND_ARM_EHABI)
129 // ask libunwind to get next frame (skip over first frame which is
130 // _Unwind_Backtrace())
131 if (__unw_step(&cursor) <= 0) {
132 _LIBUNWIND_TRACE_UNWINDING(" _backtrace: ended because cursor reached "
133 "bottom of stack, returning %d",
135 return _URC_END_OF_STACK;
138 // Get the information for this frame.
139 unw_proc_info_t frameInfo;
140 if (__unw_get_proc_info(&cursor, &frameInfo) != UNW_ESUCCESS) {
141 return _URC_END_OF_STACK;
144 // Update the pr_cache in the mock exception object.
145 const uint32_t* unwindInfo = (uint32_t *) frameInfo.unwind_info;
146 ex.pr_cache.fnstart = frameInfo.start_ip;
147 ex.pr_cache.ehtp = (_Unwind_EHT_Header *) unwindInfo;
148 ex.pr_cache.additional= frameInfo.flags;
150 struct _Unwind_Context *context = (struct _Unwind_Context *)&cursor;
151 // Get and call the personality function to unwind the frame.
152 __personality_routine handler = (__personality_routine) frameInfo.handler;
153 if (handler == NULL) {
154 return _URC_END_OF_STACK;
156 if (handler(_US_VIRTUAL_UNWIND_FRAME | _US_FORCE_UNWIND, &ex, context) !=
157 _URC_CONTINUE_UNWIND) {
158 return _URC_END_OF_STACK;
160 #endif // defined(_LIBUNWIND_ARM_EHABI)
163 if (_LIBUNWIND_TRACING_UNWINDING) {
164 char functionName[512];
165 unw_proc_info_t frame;
167 __unw_get_proc_name(&cursor, functionName, 512, &offset);
168 __unw_get_proc_info(&cursor, &frame);
169 _LIBUNWIND_TRACE_UNWINDING(
170 " _backtrace: start_ip=0x%" PRIxPTR ", func=%s, lsda=0x%" PRIxPTR ", context=%p",
171 frame.start_ip, functionName, frame.lsda,
175 // call trace function with this frame
176 result = (*callback)((struct _Unwind_Context *)(&cursor), ref);
177 if (result != _URC_NO_REASON) {
178 _LIBUNWIND_TRACE_UNWINDING(
179 " _backtrace: ended because callback returned %d", result);
185 /* Preserve legacy libgcc (pre r318024) ARM ABI mistake */
186 __sym_compat(_Unwind_Backtrace, _Unwind_Backtrace, GCC_3.3);
190 /// Find DWARF unwind info for an address 'pc' in some function.
191 _LIBUNWIND_EXPORT const void *_Unwind_Find_FDE(const void *pc,
192 struct dwarf_eh_bases *bases) {
193 // This is slow, but works.
194 // We create an unwind cursor then alter the IP to be pc
197 unw_proc_info_t info;
198 __unw_getcontext(&uc);
199 __unw_init_local(&cursor, &uc);
200 __unw_set_reg(&cursor, UNW_REG_IP, (unw_word_t)(intptr_t)pc);
201 __unw_get_proc_info(&cursor, &info);
202 bases->tbase = (uintptr_t)info.extra;
203 bases->dbase = 0; // dbase not used on Mac OS X
204 bases->func = (uintptr_t)info.start_ip;
205 _LIBUNWIND_TRACE_API("_Unwind_Find_FDE(pc=%p) => %p", pc,
206 (void *)(intptr_t) info.unwind_info);
207 return (void *)(intptr_t) info.unwind_info;
210 /// Returns the CFA (call frame area, or stack pointer at start of function)
211 /// for the current context.
212 _LIBUNWIND_EXPORT uintptr_t _Unwind_GetCFA(struct _Unwind_Context *context) {
213 unw_cursor_t *cursor = (unw_cursor_t *)context;
215 __unw_get_reg(cursor, UNW_REG_SP, &result);
216 _LIBUNWIND_TRACE_API("_Unwind_GetCFA(context=%p) => 0x%" PRIxPTR,
217 (void *)context, result);
218 return (uintptr_t)result;
222 /// Called by personality handler during phase 2 to get instruction pointer.
223 /// ipBefore is a boolean that says if IP is already adjusted to be the call
224 /// site address. Normally IP is the return address.
225 _LIBUNWIND_EXPORT uintptr_t _Unwind_GetIPInfo(struct _Unwind_Context *context,
227 _LIBUNWIND_TRACE_API("_Unwind_GetIPInfo(context=%p)", (void *)context);
228 int isSignalFrame = __unw_is_signal_frame((unw_cursor_t *)context);
229 // Negative means some kind of error (probably UNW_ENOINFO), but we have no
230 // good way to report that, and this maintains backward compatibility with the
231 // implementation that hard-coded zero in every case, even signal frames.
232 if (isSignalFrame <= 0)
236 return _Unwind_GetIP(context);
239 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
241 #if defined(__FreeBSD__)
243 // Based on LLVM's lib/ExecutionEngine/RuntimeDyld/RTDyldMemoryManager.cpp
244 // and XXX should be fixed to be alignment-safe.
245 static void processFDE(const char *addr, bool isDeregister) {
247 while ((length = *((const uint32_t *)addr)) != 0) {
248 const char *p = addr + 4;
249 if (length == 0xffffffff) {
250 length = *((const uint64_t *)p);
253 uint32_t offset = *((const uint32_t *)p);
256 __unw_remove_dynamic_fde((unw_word_t)(uintptr_t)addr);
258 __unw_add_dynamic_fde((unw_word_t)(uintptr_t)addr);
264 /// Called by programs with dynamic code generators that want to register
265 /// dynamically generated FDEs, with a libgcc-compatible API.
267 _LIBUNWIND_EXPORT void __register_frame(const void *addr) {
268 _LIBUNWIND_TRACE_API("__register_frame(%p)", addr);
269 processFDE(addr, false);
272 /// Called by programs with dynamic code generators that want to unregister
273 /// dynamically generated FDEs, with a libgcc-compatible API.
274 _LIBUNWIND_EXPORT void __deregister_frame(const void *addr) {
275 _LIBUNWIND_TRACE_API("__deregister_frame(%p)", addr);
276 processFDE(addr, true);
279 #else // defined(__FreeBSD__)
281 /// Called by programs with dynamic code generators that want
282 /// to register a dynamically generated FDE.
283 /// This function has existed on Mac OS X since 10.4, but
284 /// was broken until 10.6.
285 _LIBUNWIND_EXPORT void __register_frame(const void *fde) {
286 _LIBUNWIND_TRACE_API("__register_frame(%p)", fde);
287 __unw_add_dynamic_fde((unw_word_t)(uintptr_t)fde);
290 /// Called by programs with dynamic code generators that want
291 /// to unregister a dynamically generated FDE.
292 /// This function has existed on Mac OS X since 10.4, but
293 /// was broken until 10.6.
294 _LIBUNWIND_EXPORT void __deregister_frame(const void *fde) {
295 _LIBUNWIND_TRACE_API("__deregister_frame(%p)", fde);
296 __unw_remove_dynamic_fde((unw_word_t)(uintptr_t)fde);
299 #endif // defined(__FreeBSD__)
301 // The following register/deregister functions are gcc extensions.
302 // They have existed on Mac OS X, but have never worked because Mac OS X
303 // before 10.6 used keymgr to track known FDEs, but these functions
304 // never got updated to use keymgr.
305 // For now, we implement these as do-nothing functions to keep any existing
306 // applications working. We also add the not in 10.6 symbol so that nwe
307 // application won't be able to use them.
309 #if defined(_LIBUNWIND_SUPPORT_FRAME_APIS)
310 _LIBUNWIND_EXPORT void __register_frame_info_bases(const void *fde, void *ob,
311 void *tb, void *db) {
316 _LIBUNWIND_TRACE_API("__register_frame_info_bases(%p,%p, %p, %p)",
318 // do nothing, this function never worked in Mac OS X
321 _LIBUNWIND_EXPORT void __register_frame_info(const void *fde, void *ob) {
324 _LIBUNWIND_TRACE_API("__register_frame_info(%p, %p)", fde, ob);
325 // do nothing, this function never worked in Mac OS X
328 _LIBUNWIND_EXPORT void __register_frame_info_table_bases(const void *fde,
335 _LIBUNWIND_TRACE_API("__register_frame_info_table_bases"
336 "(%p,%p, %p, %p)", fde, ob, tb, db);
337 // do nothing, this function never worked in Mac OS X
340 _LIBUNWIND_EXPORT void __register_frame_info_table(const void *fde, void *ob) {
343 _LIBUNWIND_TRACE_API("__register_frame_info_table(%p, %p)", fde, ob);
344 // do nothing, this function never worked in Mac OS X
347 _LIBUNWIND_EXPORT void __register_frame_table(const void *fde) {
349 _LIBUNWIND_TRACE_API("__register_frame_table(%p)", fde);
350 // do nothing, this function never worked in Mac OS X
353 _LIBUNWIND_EXPORT void *__deregister_frame_info(const void *fde) {
355 _LIBUNWIND_TRACE_API("__deregister_frame_info(%p)", fde);
356 // do nothing, this function never worked in Mac OS X
360 _LIBUNWIND_EXPORT void *__deregister_frame_info_bases(const void *fde) {
362 _LIBUNWIND_TRACE_API("__deregister_frame_info_bases(%p)", fde);
363 // do nothing, this function never worked in Mac OS X
366 #endif // defined(_LIBUNWIND_SUPPORT_FRAME_APIS)
368 #endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
370 #endif // defined(_LIBUNWIND_BUILD_ZERO_COST_APIS)