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Resurrect libunwind patches (#45189)
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Fixes #44499

(cherry picked from commit f18324c)
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@fxcoudert @KristofferC
fxcoudert authored and KristofferC committed May 18, 2022
1 parent 3dfa74d commit 43ba8ae
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179 changes: 179 additions & 0 deletions deps/patches/llvm-libunwind-force-dwarf.patch
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Original file line number Diff line number Diff line change
@@ -0,0 +1,179 @@
An updated version of this libosxunwind commit:

Author: Keno Fischer <kfischer@college.harvard.edu>
Date: Tue Aug 27 15:01:22 2013 -0400

Add option to step with DWARF

---
diff -pur a/libunwind/include/libunwind.h b/libunwind/include/libunwind.h
--- a/libunwind/include/libunwind.h 2021-06-28 18:23:38.000000000 +0200
+++ b/libunwind/include/libunwind.h 2022-05-04 18:44:24.000000000 +0200
@@ -108,6 +108,7 @@ extern "C" {

extern int unw_getcontext(unw_context_t *) LIBUNWIND_AVAIL;
extern int unw_init_local(unw_cursor_t *, unw_context_t *) LIBUNWIND_AVAIL;
+extern int unw_init_local_dwarf(unw_cursor_t *, unw_context_t *) LIBUNWIND_AVAIL;
extern int unw_step(unw_cursor_t *) LIBUNWIND_AVAIL;
extern int unw_get_reg(unw_cursor_t *, unw_regnum_t, unw_word_t *) LIBUNWIND_AVAIL;
extern int unw_get_fpreg(unw_cursor_t *, unw_regnum_t, unw_fpreg_t *) LIBUNWIND_AVAIL;
Only in b/libunwind/include: libunwind.h.orig
diff -pur a/libunwind/src/UnwindCursor.hpp b/libunwind/src/UnwindCursor.hpp
--- a/libunwind/src/UnwindCursor.hpp 2021-06-28 18:23:38.000000000 +0200
+++ b/libunwind/src/UnwindCursor.hpp 2022-05-04 18:45:11.000000000 +0200
@@ -437,6 +437,9 @@ public:
virtual bool isSignalFrame() {
_LIBUNWIND_ABORT("isSignalFrame not implemented");
}
+ virtual void setForceDWARF(bool) {
+ _LIBUNWIND_ABORT("setForceDWARF not implemented");
+ }
virtual bool getFunctionName(char *, size_t, unw_word_t *) {
_LIBUNWIND_ABORT("getFunctionName not implemented");
}
@@ -894,6 +897,7 @@ public:
virtual void getInfo(unw_proc_info_t *);
virtual void jumpto();
virtual bool isSignalFrame();
+ virtual void setForceDWARF(bool force);
virtual bool getFunctionName(char *buf, size_t len, unw_word_t *off);
virtual void setInfoBasedOnIPRegister(bool isReturnAddress = false);
virtual const char *getRegisterName(int num);
@@ -963,7 +967,7 @@ private:
const UnwindInfoSections &sects);
int stepWithCompactEncoding() {
#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
- if ( compactSaysUseDwarf() )
+ if ( _forceDwarf || compactSaysUseDwarf() )
return stepWithDwarfFDE();
#endif
R dummy;
@@ -1198,6 +1202,7 @@ private:
unw_proc_info_t _info;
bool _unwindInfoMissing;
bool _isSignalFrame;
+ bool _forceDwarf;
#if defined(_LIBUNWIND_TARGET_LINUX) && defined(_LIBUNWIND_TARGET_AARCH64)
bool _isSigReturn = false;
#endif
@@ -1207,7 +1212,7 @@ private:
template <typename A, typename R>
UnwindCursor<A, R>::UnwindCursor(unw_context_t *context, A &as)
: _addressSpace(as), _registers(context), _unwindInfoMissing(false),
- _isSignalFrame(false) {
+ _isSignalFrame(false), _forceDwarf(false) {
static_assert((check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit),
"UnwindCursor<> does not fit in unw_cursor_t");
static_assert((alignof(UnwindCursor<A, R>) <= alignof(unw_cursor_t)),
@@ -1217,7 +1222,8 @@ UnwindCursor<A, R>::UnwindCursor(unw_con

template <typename A, typename R>
UnwindCursor<A, R>::UnwindCursor(A &as, void *)
- : _addressSpace(as), _unwindInfoMissing(false), _isSignalFrame(false) {
+ : _addressSpace(as), _unwindInfoMissing(false), _isSignalFrame(false),
+ _forceDwarf(false) {
memset(&_info, 0, sizeof(_info));
// FIXME
// fill in _registers from thread arg
@@ -1273,6 +1279,10 @@ template <typename A, typename R> bool U
return _isSignalFrame;
}

+template <typename A, typename R> void UnwindCursor<A, R>::setForceDWARF(bool force) {
+ _forceDwarf = force;
+}
+
#endif // defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)

#if defined(_LIBUNWIND_ARM_EHABI)
@@ -1941,7 +1951,13 @@ void UnwindCursor<A, R>::setInfoBasedOnI
// record that we have no unwind info.
if (_info.format == 0)
_unwindInfoMissing = true;
+ #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
+ if (!(_forceDwarf || compactSaysUseDwarf(&dwarfOffset)))
+ return;
+ #else
return;
+ #endif
+
}
}
#endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
diff -pur a/libunwind/src/libunwind.cpp b/libunwind/src/libunwind.cpp
--- a/libunwind/src/libunwind.cpp 2021-06-28 18:23:38.000000000 +0200
+++ b/libunwind/src/libunwind.cpp 2022-05-04 18:44:24.000000000 +0200
@@ -71,6 +71,7 @@ _LIBUNWIND_HIDDEN int __unw_init_local(u
new (reinterpret_cast<UnwindCursor<LocalAddressSpace, REGISTER_KIND> *>(cursor))
UnwindCursor<LocalAddressSpace, REGISTER_KIND>(
context, LocalAddressSpace::sThisAddressSpace);
+ static_assert(sizeof(unw_cursor_t) >= sizeof(UnwindCursor<LocalAddressSpace,REGISTER_KIND>), "libunwind header outdated");
#undef REGISTER_KIND
AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
co->setInfoBasedOnIPRegister();
@@ -79,6 +80,54 @@ _LIBUNWIND_HIDDEN int __unw_init_local(u
}
_LIBUNWIND_WEAK_ALIAS(__unw_init_local, unw_init_local)

+_LIBUNWIND_HIDDEN int __unw_init_local_dwarf(unw_cursor_t *cursor,
+ unw_context_t *context) {
+ _LIBUNWIND_TRACE_API("__unw_init_local_dwarf(cursor=%p, context=%p)",
+ static_cast<void *>(cursor),
+ static_cast<void *>(context));
+#if defined(__i386__)
+# define REGISTER_KIND Registers_x86
+#elif defined(__x86_64__)
+# define REGISTER_KIND Registers_x86_64
+#elif defined(__powerpc64__)
+# define REGISTER_KIND Registers_ppc64
+#elif defined(__ppc__)
+# define REGISTER_KIND Registers_ppc
+#elif defined(__aarch64__)
+# define REGISTER_KIND Registers_arm64
+#elif defined(__arm__)
+# define REGISTER_KIND Registers_arm
+#elif defined(__or1k__)
+# define REGISTER_KIND Registers_or1k
+#elif defined(__hexagon__)
+# define REGISTER_KIND Registers_hexagon
+#elif defined(__mips__) && defined(_ABIO32) && _MIPS_SIM == _ABIO32
+# define REGISTER_KIND Registers_mips_o32
+#elif defined(__mips64)
+# define REGISTER_KIND Registers_mips_newabi
+#elif defined(__mips__)
+# warning The MIPS architecture is not supported with this ABI and environment!
+#elif defined(__sparc__)
+# define REGISTER_KIND Registers_sparc
+#elif defined(__riscv) && __riscv_xlen == 64
+# define REGISTER_KIND Registers_riscv
+#else
+# error Architecture not supported
+#endif
+ // Use "placement new" to allocate UnwindCursor in the cursor buffer.
+ new (reinterpret_cast<UnwindCursor<LocalAddressSpace, REGISTER_KIND> *>(cursor))
+ UnwindCursor<LocalAddressSpace, REGISTER_KIND>(
+ context, LocalAddressSpace::sThisAddressSpace);
+ static_assert(sizeof(unw_cursor_t) >= sizeof(UnwindCursor<LocalAddressSpace,REGISTER_KIND>), "libunwind header outdated");
+#undef REGISTER_KIND
+ AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
+ co->setForceDWARF(true);
+ co->setInfoBasedOnIPRegister();
+
+ return UNW_ESUCCESS;
+}
+_LIBUNWIND_WEAK_ALIAS(__unw_init_local_dwarf, unw_init_local_dwarf)
+
/// Get value of specified register at cursor position in stack frame.
_LIBUNWIND_HIDDEN int __unw_get_reg(unw_cursor_t *cursor, unw_regnum_t regNum,
unw_word_t *value) {
diff -pur a/libunwind/src/libunwind_ext.h b/libunwind/src/libunwind_ext.h
--- a/libunwind/src/libunwind_ext.h 2021-06-28 18:23:38.000000000 +0200
+++ b/libunwind/src/libunwind_ext.h 2022-05-04 18:44:24.000000000 +0200
@@ -25,6 +25,7 @@ extern "C" {

extern int __unw_getcontext(unw_context_t *);
extern int __unw_init_local(unw_cursor_t *, unw_context_t *);
+extern int __unw_init_local_dwarf(unw_cursor_t *, unw_context_t *);
extern int __unw_step(unw_cursor_t *);
extern int __unw_get_reg(unw_cursor_t *, unw_regnum_t, unw_word_t *);
extern int __unw_get_fpreg(unw_cursor_t *, unw_regnum_t, unw_fpreg_t *);
107 changes: 107 additions & 0 deletions deps/patches/llvm-libunwind-freebsd-libgcc-api-compat.patch
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@@ -0,0 +1,107 @@
Modification of the following patch in the FreeBSD source tree, which
includes LLVM libunwind in contrib/llvm-project/libunwind.

From 9f287522cec9feac040d7cb845a440a8f6b7b90e Mon Sep 17 00:00:00 2001
From: Dimitry Andric <dim@FreeBSD.org>
Date: Sun, 2 Aug 2020 18:12:14 +0000
Subject: [PATCH] Reapply r310365 (by emaste):

libunwind: make __{de,}register_frame compatible with libgcc API

The libgcc __register_frame and __deregister_frame functions take a
pointer to a set of FDE/CIEs, terminated by an entry where length is 0.

In Apple's libunwind implementation the pointer is taken to be to a
single FDE. I suspect this was just an Apple bug, compensated by Apple-
specific code in LLVM.

See lib/ExecutionEngine/RuntimeDyld/RTDyldMemoryManager.cpp and
http://lists.llvm.org/pipermail/llvm-dev/2013-April/061737.html
for more detail.

This change is based on the LLVM RTDyldMemoryManager.cpp. It should
later be changed to be alignment-safe.

Reported by: dim
Reviewed by: dim
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D8869

Reapply r351610:

Update libunwind custom frame register and deregister functions for
FreeBSD: use the new doubly underscored names for unw_add_dynamic_fde
and unw_remove_dynamic_fde.

NOTE: this should be upstreamed...
---
.../libunwind/src/UnwindLevel1-gcc-ext.c | 42 ++++++++++++++++++-
1 file changed, 41 insertions(+), 1 deletion(-)

diff --git a/libunwind/src/UnwindLevel1-gcc-ext.c b/libunwind/src/UnwindLevel1-gcc-ext.c
index 310b836d129e5..30f9cabf241f2 100644
--- a/libunwind/src/UnwindLevel1-gcc-ext.c
+++ b/libunwind/src/UnwindLevel1-gcc-ext.c
@@ -234,6 +234,46 @@ _LIBUNWIND_EXPORT uintptr_t _Unwind_GetIPInfo(struct _Unwind_Context *context,

#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)

+#if defined(__FreeBSD__)
+
+// Based on LLVM's lib/ExecutionEngine/RuntimeDyld/RTDyldMemoryManager.cpp
+// and XXX should be fixed to be alignment-safe.
+static void processFDE(const char *addr, bool isDeregister) {
+ uint64_t length;
+ while ((length = *((const uint32_t *)addr)) != 0) {
+ const char *p = addr + 4;
+ if (length == 0xffffffff) {
+ length = *((const uint64_t *)p);
+ p += 8;
+ }
+ uint32_t offset = *((const uint32_t *)p);
+ if (offset != 0) {
+ if (isDeregister)
+ __unw_remove_dynamic_fde((unw_word_t)(uintptr_t)addr);
+ else
+ __unw_add_dynamic_fde((unw_word_t)(uintptr_t)addr);
+ }
+ addr = p + length;
+ }
+}
+
+/// Called by programs with dynamic code generators that want to register
+/// dynamically generated FDEs, with a libgcc-compatible API.
+
+_LIBUNWIND_EXPORT void __register_frame(const void *addr) {
+ _LIBUNWIND_TRACE_API("__register_frame(%p)", addr);
+ processFDE(addr, false);
+}
+
+/// Called by programs with dynamic code generators that want to unregister
+/// dynamically generated FDEs, with a libgcc-compatible API.
+_LIBUNWIND_EXPORT void __deregister_frame(const void *addr) {
+ _LIBUNWIND_TRACE_API("__deregister_frame(%p)", addr);
+ processFDE(addr, true);
+}
+
+#else // defined(__FreeBSD__)
+
/// Called by programs with dynamic code generators that want
/// to register a dynamically generated FDE.
/// This function has existed on Mac OS X since 10.4, but
@@ -243,7 +283,6 @@ _LIBUNWIND_EXPORT void __register_frame(const void *fde) {
__unw_add_dynamic_fde((unw_word_t)(uintptr_t)fde);
}

-
/// Called by programs with dynamic code generators that want
/// to unregister a dynamically generated FDE.
/// This function has existed on Mac OS X since 10.4, but
@@ -253,6 +292,7 @@ _LIBUNWIND_EXPORT void __deregister_frame(const void *fde) {
__unw_remove_dynamic_fde((unw_word_t)(uintptr_t)fde);
}

+#endif // defined(__FreeBSD__)

// The following register/deregister functions are gcc extensions.
// They have existed on Mac OS X, but have never worked because Mac OS X
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