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Re: How to insert dynamic code? (continued)
Daniel Jacobowitz wrote:
On Thu, Jul 13, 2006 at 05:06:25PM +0200, jacob navia wrote:
So, what happens when _Unwind_Find_registered_FDE is called? Does it
find the EH data you have registered?
Yes but then it stops there instead of going upwards and finding the catch!
It is as my insertion left the list of registered routines in a bad state.
I will look again at this part (the registering part) and will try to
find out what
is going on.
It sounds to me more like it used your data, and then was left pointing
somewhere garbage, not to the next frame. That is, it sounds like
there's something wrong with your generated unwind tables. That's the
usual cause for unexpected end of stack.
Yeah...
My fault obviously, who else?
Problem is, there are so mny undocumented stuff that I do not see how I
could
avoid making a mistake here.
1) I generate exactly the same code now as gcc:
Prolog:
push %ebp
movq %rsp,%rbp
subq xxx,%rsp
and I do not touch the stack any more. Nothing is pushed, in the "xxx"
is already the stack
space for argument pushing reserved, just as gcc does. This took me 3
weeks to do.
Now, I write my stuff as follows:
1) CIE
2) FDE for function 1
..... 1 fde for each function
3) Empty FDE to zero terminate the stuff.
4) Table of pointers to the CIE, then to the FDE
p = result.FunctionTable; // Starting place, where CIE, then
FDEs are written
p = WriteCIE(p); // Write first the CIE
pFI = DefinedFunctions;
nbOfFunctions=0;
pFdeTable[nbOfFunctions++] = result.FunctionTable;
while (pFI) { // For each function, write the FDE
fde_start = p;
p = Write32(0,p); // reserve place for length field (4
bytes)
p = Write32(p - result.FunctionTable,p); //Write offset
to CIE
symbolP = pFI->FunctionInfo.AssemblerSymbol;
adr = (long long)symbolP->SymbolValue;
adr += (unsigned long long)code_start; // code_start is
the pointer to the Jitted code
p = Write64(adr,p);
p = Write64(pFI->FunctionSize,p); // Write the length in
bytes of the function
*p++ = 0x41;/// Write the opcodes
*p++ = 0x0e; // This opcodes are the same as gcc writes
*p++ = 0x10;
*p++ = 0x86;
*p++ = 0x02;
*p++ = 0x43;
*p++ = 0x0d;
*p++ = 0x06;
p = align8(p);
Write32((p - fde_start)-4,fde_start);// Fix the length
of the FDE
pFdeTable[nbOfFunctions] = fde_start; // Save pointer to
it in table
nbOfFunctions++;
pFI = pFI->Next; // loop
}
The WriteCIE function is this:
static unsigned char *WriteCIE(unsigned char *start)
{
start = Write32(0x14,start);
start = Write32(0,start);
*start++ = 1; // version 1
*start++ = 0; // no augmentation
*start++ = 1;
*start++ = 0x78;
*start++ = 0x10;
*start++ = 0xc;
*start++ = 7;
*start++ = 8;
*start++ = 0x90;
*start++ = 1;
*start++ = 0;
*start++ = 0;
start = Write32(0,start);
return start;
}
I hope this is OK...
jacob