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Revert libunwind change to fix backtrace segfault on aarch64

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Revert commit 22b615a96593 from llvm git (by Daniel Kiss):

  [libunwind] Support for leaf function unwinding.

  Unwinding leaf function is useful in cases when the backtrace finds a
  leaf function for example when it caused a signal.
  This patch also add the support for the DW_CFA_undefined because it marks
  the end of the frames.

  Ryan Prichard provided code for the tests.

  Reviewed By: #libunwind, mstorsjo

  Differential Revision: https://reviews.llvm.org/D83573

  Reland with limit the test to the x86_64-linux target.

Bisection has shown that this particular upstream commit causes programs
using backtrace(3) on aarch64 to segfault. This affects the lang/rust
port, for instance. Until we can upstream to fix this problem, revert
the commit for now.

Reported by:	mikael
PR:		256864
This commit is contained in:
Dimitry Andric 2021-07-03 00:35:42 +02:00
parent b3dc6f137b
commit 5866c369e4
2 changed files with 2 additions and 10 deletions
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9
contrib/llvm-project/libunwind/src/DwarfInstructions.hpp
View File

@ -93,8 +93,7 @@ typename A::pint_t DwarfInstructions<A, R>::getSavedRegister(
case CFI_Parser<A>::kRegisterInRegister:
return registers.getRegister((int)savedReg.value);
case CFI_Parser<A>::kRegisterUndefined:
return 0;
case CFI_Parser<A>::kRegisterUnused:
case CFI_Parser<A>::kRegisterOffsetFromCFA:
// FIX ME
@ -118,7 +117,6 @@ double DwarfInstructions<A, R>::getSavedFloatRegister(
case CFI_Parser<A>::kRegisterIsExpression:
case CFI_Parser<A>::kRegisterUnused:
case CFI_Parser<A>::kRegisterUndefined:
case CFI_Parser<A>::kRegisterOffsetFromCFA:
case CFI_Parser<A>::kRegisterInRegister:
// FIX ME
@ -142,7 +140,6 @@ v128 DwarfInstructions<A, R>::getSavedVectorRegister(
case CFI_Parser<A>::kRegisterIsExpression:
case CFI_Parser<A>::kRegisterUnused:
case CFI_Parser<A>::kRegisterUndefined:
case CFI_Parser<A>::kRegisterOffsetFromCFA:
case CFI_Parser<A>::kRegisterInRegister:
// FIX ME
@ -193,10 +190,6 @@ int DwarfInstructions<A, R>::stepWithDwarf(A &addressSpace, pint_t pc,
prolog.savedRegisters[i]));
else
return UNW_EBADREG;
} else if (i == (int)cieInfo.returnAddressRegister) {
// Leaf function keeps the return address in register and there is no
// explicit intructions how to restore it.
returnAddress = registers.getRegister(cieInfo.returnAddressRegister);
}
}

3
contrib/llvm-project/libunwind/src/DwarfParser.hpp
View File

@ -69,7 +69,6 @@ public:
};
enum RegisterSavedWhere {
kRegisterUnused,
kRegisterUndefined,
kRegisterInCFA,
kRegisterOffsetFromCFA,
kRegisterInRegister,
@ -503,7 +502,7 @@ bool CFI_Parser<A>::parseFDEInstructions(A &addressSpace,
"malformed DW_CFA_undefined DWARF unwind, reg too big");
return false;
}
results->setRegisterLocation(reg, kRegisterUndefined, initialState);
results->setRegisterLocation(reg, kRegisterUnused, initialState);
_LIBUNWIND_TRACE_DWARF("DW_CFA_undefined(reg=%" PRIu64 ")\n", reg);
break;
case DW_CFA_same_value: