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Fix DW_CFA_GNU_args_size handling. The primary architecture using this 

opcode is VAX. A function call pushes the number of arguments given onto
the stack and "ret" will pop it automatically. The FDE of the caller
contains the amount of stack space used for arguments (and possibly
extra padding), so unwinding has to compensate for this when "returning"
from a function. This is exactly the case when step() is done. The
existing handling in _Unwind_SetIP no longer makes sense.
This commit is contained in:
joerg 2014-03-20 01:35:45 +00:00
parent 5c08b734f4
commit 1fad0e91e1
2 changed files with 3 additions and 5 deletions
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3
sys/lib/libunwind/UnwindCursor.hpp
View File

@ -61,6 +61,9 @@ public:
this->setInfoBasedOnIPRegister(true);
if (fUnwindInfoMissing)
return UNW_STEP_END;
if (fInfo.extra_args)
setSP(getSP() + fInfo.extra_args);
return UNW_STEP_SUCCESS;
}
__builtin_unreachable();

5
sys/lib/libunwind/libunwind.cxx
View File

@ -288,12 +288,7 @@ void _Unwind_SetIP(struct _Unwind_Context *context, uintptr_t new_value) {
cursor->setIP(new_value);
unw_proc_info_t info;
cursor->getInfo(&info);
uint64_t orgArgSize = info.extra_args;
uint64_t orgFuncStart = info.start_ip;
cursor->setInfoBasedOnIPRegister(false);
// Adjust REG_SP if there was a DW_CFA_GNU_args_size.
if (orgFuncStart == info.start_ip && orgArgSize != 0)
cursor->setSP(cursor->getSP() + orgArgSize);
}
uintptr_t _Unwind_GetRegionStart(struct _Unwind_Context *context) {