<html><head><meta http-equiv="Content-Type" content="text/html charset=iso-8859-1"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div>Yaron,</div><div><br></div><div>Each separately linked image (program, DLLs, etc) has its own set of FDEs (in its .eh_frame) section. The method LocalAddressSpace::findUnwindSections() needs to be updated in an OS specific way to: 1) find the image for a given pc value, and 2) find the .eh_frame section bounds for that image.</div><div><br></div><div>-Nick</div><div><br></div><br><div><div>On Oct 30, 2013, at 3:03 PM, Yaron Keren <<a href="mailto:yaron.keren@gmail.com">yaron.keren@gmail.com</a>> wrote:</div><blockquote type="cite"><div dir="rtl"><div dir="ltr">Hi Nick,</div><div dir="ltr"><br></div><div dir="ltr">I looked at the disassembly, unw_getcontext() gets the correct IP into the context and later setInfoBasedOnIPRegister gets it right into "pc". This is OK.!
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<div dir="ltr"> </div><div dir="ltr">The trouble is, the whole address space is nowhere near the fde values. For example, </div><div dir="ltr"><br></div><div dir="ltr"><font face="courier new, monospace">p = 0x66179070 <libunwind::DwarfFDECache<libunwind::LocalAddressSpace>::_initialBuffer></font></div>
<div dir="ltr"><font face="courier new, monospace">pc = 0x6604e7d9</font></div><div dir="ltr"><font face="courier new, monospace">fde = 0x40801c0</font></div><div dir="ltr"><font face="courier new, monospace">p->ip_start = 0x4080010</font></div>
<div dir="ltr"><font face="courier new, monospace">p->ip_end = 0x408010c</font></div><div dir="ltr"><br></div><div dir="ltr">p is consistent with pc and local vars and addresses in unwind.dll (0x66YYYYYY)</div><div dir="ltr">
fde is consistent with the ip ranges and with the caller of unwind.dll (the throwing function) address space (0x40800YY)</div><div dir="ltr"><br></div><div dir="ltr">they live in different memory ranges, the fde addresses are in caller range whereas the unwind addresses are in the DLL range so when it tries to find its IP in the fde tables it can't find.</div>
<div dir="ltr"><br></div><div dir="ltr">It's as if the DLL is supposed to load in other memory range, some linker option required?</div><div dir="ltr"><br></div><div dir="ltr">Yaron</div><div dir="ltr"><br></div></div>
<div class="gmail_extra"><br><br><div class="gmail_quote"><div dir="ltr">2013/10/29 Nick Kledzik <span dir="ltr"><<a href="mailto:kledzik@apple.com" target="_blank">kledzik@apple.com</a>></span></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div class="HOEnZb"><div class="h5"><br>
On Oct 29, 2013, at 12:11 AM, Yaron Keren <<a href="mailto:yaron.keren@gmail.com">yaron.keren@gmail.com</a>> wrote:<br>
<br>
> Hello,<br>
><br>
> I'm trying to make libcxxabi / Unwind work on Windows / MingW 32 bit. Attached is a patch to make it compile without warnings and run without crashing.<br>
><br>
> However the functionality isn't working yet: upon exception, the IP seems to be completely out of range the FDE tables. This may be related to the memory model / compilation options???<br>
</div></div>Take a look at UnwindRegisterRestore.s. When an exception is thrown, unw_getcontext() is called which saves all registers and the return address into a register struct. Then the FDE info is used to step through each frame and modify the register set. At which step is the IP register out of bounds?<br>
<br>
It might be that the C files need to be compiled with -fexceptions so that they have unwind tables.<br>
<span class="HOEnZb"><font color="#888888"><br>
-Nick<br>
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