pe32: tls refactoring
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László Molnár
-137
@@ -162,143 +162,6 @@ int PackW32Pe::readFileHeader()
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return super::readFileHeader();
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}
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//new: processTLS moved to p_w32pe.cpp for TLS callback support
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/*************************************************************************
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// TLS handling
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**************************************************************************/
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// thanks for theowl for providing me some docs, so that now I understand
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// what I'm doing here :)
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// 1999-10-17: this was tricky to find:
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// when the fixup records and the tls area are on the same page, then
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// the tls area is not relocated, because the relocation is done by
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// the virtual memory manager only for pages which are not yet loaded.
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// of course it was impossible to debug this ;-)
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#define TLS_CB_ALIGNMENT 4u // alignment of tls callbacks
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__packed_struct(tls)
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LE32 datastart; // VA tls init data start
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LE32 dataend; // VA tls init data end
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LE32 tlsindex; // VA tls index
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LE32 callbacks; // VA tls callbacks
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char _[8]; // zero init, characteristics
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__packed_struct_end()
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void PackW32Pe::processTls(Interval *iv) // pass 1
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{
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COMPILE_TIME_ASSERT(sizeof(tls) == 24)
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COMPILE_TIME_ASSERT_ALIGNED1(tls)
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if ((sotls = ALIGN_UP(IDSIZE(PEDIR_TLS),4)) == 0)
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return;
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const tls * const tlsp = (const tls*) (ibuf + IDADDR(PEDIR_TLS));
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// note: TLS callbacks are not implemented in Windows 95/98/ME
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if (tlsp->callbacks)
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{
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if (tlsp->callbacks < ih.imagebase)
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throwCantPack("invalid TLS callback");
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else if (tlsp->callbacks - ih.imagebase + 4 >= ih.imagesize)
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throwCantPack("invalid TLS callback");
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unsigned v = get_le32(ibuf + tlsp->callbacks - ih.imagebase);
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//NEW: TLS callback support - Stefan Widmann
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if(v != 0)
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{
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//count number of callbacks, just for information string - Stefan Widmann
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unsigned num_callbacks = 0;
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unsigned callback_offset = 0;
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while(get_le32(ibuf + tlsp->callbacks - ih.imagebase + callback_offset))
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{
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//increment number of callbacks
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num_callbacks++;
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//increment pointer by 4
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callback_offset += 4;
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}
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info("TLS: %u callback(s) found, adding TLS callback handler", num_callbacks);
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//set flag to include necessary sections in loader
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use_tls_callbacks = true;
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//define linker symbols
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tlscb_ptr = tlsp->callbacks;
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}
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}
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const unsigned tlsdatastart = tlsp->datastart - ih.imagebase;
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const unsigned tlsdataend = tlsp->dataend - ih.imagebase;
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// now some ugly stuff: find the relocation entries in the tls data area
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unsigned pos,type;
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Reloc rel(ibuf + IDADDR(PEDIR_RELOC),IDSIZE(PEDIR_RELOC));
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while (rel.next(pos,type))
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if (pos >= tlsdatastart && pos < tlsdataend)
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iv->add(pos,type);
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sotls = sizeof(tls) + tlsdataend - tlsdatastart;
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// if TLS callbacks are used, we need two more DWORDS at the end of the TLS
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// ... and those dwords should be correctly aligned
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if (use_tls_callbacks)
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sotls = ALIGN_UP(sotls, TLS_CB_ALIGNMENT) + 8;
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// the PE loader wants this stuff uncompressed
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otls = new upx_byte[sotls];
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memset(otls,0,sotls);
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memcpy(otls,ibuf + IDADDR(PEDIR_TLS),sizeof(tls));
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// WARNING: this can acces data in BSS
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memcpy(otls + sizeof(tls),ibuf + tlsdatastart,sotls - sizeof(tls));
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tlsindex = tlsp->tlsindex - ih.imagebase;
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//NEW: subtract two dwords if TLS callbacks are used - Stefan Widmann
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info("TLS: %u bytes tls data and %u relocations added",sotls - (unsigned) sizeof(tls) - (use_tls_callbacks ? 8 : 0),iv->ivnum);
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// makes sure tls index is zero after decompression
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if (tlsindex && tlsindex < ih.imagesize)
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set_le32(ibuf + tlsindex, 0);
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}
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void PackW32Pe::processTls(Reloc *rel,const Interval *iv,unsigned newaddr) // pass 2
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{
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if (sotls == 0)
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return;
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// add new relocation entries
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unsigned ic;
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//NEW: if TLS callbacks are used, relocate the VA of the callback chain, too - Stefan Widmann
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for (ic = 0; ic < (use_tls_callbacks ? 16u : 12u); ic += 4)
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rel->add(newaddr + ic,3);
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tls * const tlsp = (tls*) otls;
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// now the relocation entries in the tls data area
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for (ic = 0; ic < iv->ivnum; ic += 4)
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{
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void *p = otls + iv->ivarr[ic].start - (tlsp->datastart - ih.imagebase) + sizeof(tls);
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unsigned kc = get_le32(p);
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if (kc < tlsp->dataend && kc >= tlsp->datastart)
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{
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kc += newaddr + sizeof(tls) - tlsp->datastart;
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set_le32(p,kc + ih.imagebase);
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rel->add(kc,iv->ivarr[ic].len);
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}
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else
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rel->add(kc - ih.imagebase,iv->ivarr[ic].len);
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}
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const unsigned tls_data_size = tlsp->dataend - tlsp->datastart;
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tlsp->datastart = newaddr + sizeof(tls) + ih.imagebase;
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tlsp->dataend = tlsp->datastart + tls_data_size;
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//NEW: if we have TLS callbacks to handle, we create a pointer to the new callback chain - Stefan Widmann
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tlsp->callbacks = (use_tls_callbacks ? newaddr + sotls + ih.imagebase - 8 : 0);
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if(use_tls_callbacks)
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{
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//set handler offset
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set_le32(otls + sotls - 8, tls_handler_offset + ih.imagebase);
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//add relocation for TLS handler offset
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rel->add(newaddr + sotls - 8, 3);
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}
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}
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/*************************************************************************
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// Load Configuration handling
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**************************************************************************/
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