[libunwind] 09d4929 - [libunwind] Bare-metal DWARF: set dso_base to 0

Ryan Prichard via cfe-commits cfe-commits at lists.llvm.org
Wed Sep 9 15:43:49 PDT 2020


Author: Ryan Prichard
Date: 2020-09-09T15:43:35-07:00
New Revision: 09d492902f178f60b3ab986360eadde9b5c8d359

URL: https://github.com/llvm/llvm-project/commit/09d492902f178f60b3ab986360eadde9b5c8d359
DIFF: https://github.com/llvm/llvm-project/commit/09d492902f178f60b3ab986360eadde9b5c8d359.diff

LOG: [libunwind] Bare-metal DWARF: set dso_base to 0

Previously, DwarfFDECache::findFDE used 0 as a special value meaning
"search the entire cache, including dynamically-registered FDEs".
Switch this special value to -1, which doesn't make sense as a DSO
base.

Fixes PR47335.

Reviewed By: compnerd, #libunwind

Differential Revision: https://reviews.llvm.org/D86748

Added: 
    

Modified: 
    libunwind/src/AddressSpace.hpp
    libunwind/src/UnwindCursor.hpp

Removed: 
    


################################################################################
diff  --git a/libunwind/src/AddressSpace.hpp b/libunwind/src/AddressSpace.hpp
index cc298c9bbb83..eccc2153c697 100644
--- a/libunwind/src/AddressSpace.hpp
+++ b/libunwind/src/AddressSpace.hpp
@@ -518,6 +518,7 @@ inline bool LocalAddressSpace::findUnwindSections(pint_t targetAddr,
     return true;
   }
 #elif defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND) && defined(_LIBUNWIND_IS_BAREMETAL)
+  info.dso_base = 0;
   // Bare metal is statically linked, so no need to ask the dynamic loader
   info.dwarf_section_length = (uintptr_t)(&__eh_frame_end - &__eh_frame_start);
   info.dwarf_section =        (uintptr_t)(&__eh_frame_start);

diff  --git a/libunwind/src/UnwindCursor.hpp b/libunwind/src/UnwindCursor.hpp
index e6a36764fc79..206b5e398321 100644
--- a/libunwind/src/UnwindCursor.hpp
+++ b/libunwind/src/UnwindCursor.hpp
@@ -81,6 +81,7 @@ template <typename A>
 class _LIBUNWIND_HIDDEN DwarfFDECache {
   typedef typename A::pint_t pint_t;
 public:
+  static constexpr pint_t kSearchAll = static_cast<pint_t>(-1);
   static pint_t findFDE(pint_t mh, pint_t pc);
   static void add(pint_t mh, pint_t ip_start, pint_t ip_end, pint_t fde);
   static void removeAllIn(pint_t mh);
@@ -138,7 +139,7 @@ typename A::pint_t DwarfFDECache<A>::findFDE(pint_t mh, pint_t pc) {
   pint_t result = 0;
   _LIBUNWIND_LOG_IF_FALSE(_lock.lock_shared());
   for (entry *p = _buffer; p < _bufferUsed; ++p) {
-    if ((mh == p->mh) || (mh == 0)) {
+    if ((mh == p->mh) || (mh == kSearchAll)) {
       if ((p->ip_start <= pc) && (pc < p->ip_end)) {
         result = p->fde;
         break;
@@ -1945,7 +1946,8 @@ void UnwindCursor<A, R>::setInfoBasedOnIPRegister(bool isReturnAddress) {
 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
   // There is no static unwind info for this pc. Look to see if an FDE was
   // dynamically registered for it.
-  pint_t cachedFDE = DwarfFDECache<A>::findFDE(0, pc);
+  pint_t cachedFDE = DwarfFDECache<A>::findFDE(DwarfFDECache<A>::kSearchAll,
+                                               pc);
   if (cachedFDE != 0) {
     typename CFI_Parser<A>::FDE_Info fdeInfo;
     typename CFI_Parser<A>::CIE_Info cieInfo;


        


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