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-rw-r--r--src/EHHeaderParser.hpp161
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diff --git a/src/EHHeaderParser.hpp b/src/EHHeaderParser.hpp
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+//===------------------------- EHHeaderParser.hpp -------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//
+// Parses ELF .eh_frame_hdr sections.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef __EHHEADERPARSER_HPP__
+#define __EHHEADERPARSER_HPP__
+
+#include "libunwind.h"
+
+#include "AddressSpace.hpp"
+#include "DwarfParser.hpp"
+
+namespace libunwind {
+
+/// \brief EHHeaderParser does basic parsing of an ELF .eh_frame_hdr section.
+///
+/// See DWARF spec for details:
+/// http://refspecs.linuxbase.org/LSB_3.1.0/LSB-Core-generic/LSB-Core-generic/ehframechpt.html
+///
+template <typename A> class EHHeaderParser {
+public:
+ typedef typename A::pint_t pint_t;
+
+ /// Information encoded in the EH frame header.
+ struct EHHeaderInfo {
+ pint_t eh_frame_ptr;
+ size_t fde_count;
+ pint_t table;
+ uint8_t table_enc;
+ };
+
+ static void decodeEHHdr(A &addressSpace, pint_t ehHdrStart, pint_t ehHdrEnd,
+ EHHeaderInfo &ehHdrInfo);
+ static bool findFDE(A &addressSpace, pint_t pc, pint_t ehHdrStart,
+ uint32_t sectionLength,
+ typename CFI_Parser<A>::FDE_Info *fdeInfo,
+ typename CFI_Parser<A>::CIE_Info *cieInfo);
+
+private:
+ static bool decodeTableEntry(A &addressSpace, pint_t &tableEntry,
+ pint_t ehHdrStart, pint_t ehHdrEnd,
+ uint8_t tableEnc,
+ typename CFI_Parser<A>::FDE_Info *fdeInfo,
+ typename CFI_Parser<A>::CIE_Info *cieInfo);
+ static size_t getTableEntrySize(uint8_t tableEnc);
+};
+
+template <typename A>
+void EHHeaderParser<A>::decodeEHHdr(A &addressSpace, pint_t ehHdrStart,
+ pint_t ehHdrEnd, EHHeaderInfo &ehHdrInfo) {
+ pint_t p = ehHdrStart;
+ uint8_t version = addressSpace.get8(p++);
+ if (version != 1)
+ _LIBUNWIND_ABORT("Unsupported .eh_frame_hdr version");
+
+ uint8_t eh_frame_ptr_enc = addressSpace.get8(p++);
+ uint8_t fde_count_enc = addressSpace.get8(p++);
+ ehHdrInfo.table_enc = addressSpace.get8(p++);
+
+ ehHdrInfo.eh_frame_ptr =
+ addressSpace.getEncodedP(p, ehHdrEnd, eh_frame_ptr_enc, ehHdrStart);
+ ehHdrInfo.fde_count =
+ addressSpace.getEncodedP(p, ehHdrEnd, fde_count_enc, ehHdrStart);
+ ehHdrInfo.table = p;
+}
+
+template <typename A>
+bool EHHeaderParser<A>::decodeTableEntry(
+ A &addressSpace, pint_t &tableEntry, pint_t ehHdrStart, pint_t ehHdrEnd,
+ uint8_t tableEnc, typename CFI_Parser<A>::FDE_Info *fdeInfo,
+ typename CFI_Parser<A>::CIE_Info *cieInfo) {
+ // Have to decode the whole FDE for the PC range anyway, so just throw away
+ // the PC start.
+ addressSpace.getEncodedP(tableEntry, ehHdrEnd, tableEnc, ehHdrStart);
+ pint_t fde =
+ addressSpace.getEncodedP(tableEntry, ehHdrEnd, tableEnc, ehHdrStart);
+ const char *message =
+ CFI_Parser<A>::decodeFDE(addressSpace, fde, fdeInfo, cieInfo);
+ if (message != NULL) {
+ _LIBUNWIND_DEBUG_LOG("EHHeaderParser::decodeTableEntry: bad fde: %s\n",
+ message);
+ return false;
+ }
+
+ return true;
+}
+
+template <typename A>
+bool EHHeaderParser<A>::findFDE(A &addressSpace, pint_t pc, pint_t ehHdrStart,
+ uint32_t sectionLength,
+ typename CFI_Parser<A>::FDE_Info *fdeInfo,
+ typename CFI_Parser<A>::CIE_Info *cieInfo) {
+ pint_t ehHdrEnd = ehHdrStart + sectionLength;
+
+ EHHeaderParser<A>::EHHeaderInfo hdrInfo;
+ EHHeaderParser<A>::decodeEHHdr(addressSpace, ehHdrStart, ehHdrEnd, hdrInfo);
+
+ size_t tableEntrySize = getTableEntrySize(hdrInfo.table_enc);
+ pint_t tableEntry;
+
+ size_t low = 0;
+ for (size_t len = hdrInfo.fde_count; len > 1;) {
+ size_t mid = low + (len / 2);
+ tableEntry = hdrInfo.table + mid * tableEntrySize;
+ pint_t start = addressSpace.getEncodedP(tableEntry, ehHdrEnd,
+ hdrInfo.table_enc, ehHdrStart);
+
+ if (start == pc) {
+ low = mid;
+ break;
+ } else if (start < pc) {
+ low = mid;
+ len -= (len / 2);
+ } else {
+ len /= 2;
+ }
+ }
+
+ tableEntry = hdrInfo.table + low * tableEntrySize;
+ if (decodeTableEntry(addressSpace, tableEntry, ehHdrStart, ehHdrEnd,
+ hdrInfo.table_enc, fdeInfo, cieInfo)) {
+ if (pc >= fdeInfo->pcStart && pc < fdeInfo->pcEnd)
+ return true;
+ }
+
+ return false;
+}
+
+template <typename A>
+size_t EHHeaderParser<A>::getTableEntrySize(uint8_t tableEnc) {
+ switch (tableEnc & 0x0f) {
+ case DW_EH_PE_sdata2:
+ case DW_EH_PE_udata2:
+ return 4;
+ case DW_EH_PE_sdata4:
+ case DW_EH_PE_udata4:
+ return 8;
+ case DW_EH_PE_sdata8:
+ case DW_EH_PE_udata8:
+ return 16;
+ case DW_EH_PE_sleb128:
+ case DW_EH_PE_uleb128:
+ _LIBUNWIND_ABORT("Can't binary search on variable length encoded data.");
+ case DW_EH_PE_omit:
+ return 0;
+ default:
+ _LIBUNWIND_ABORT("Unknown DWARF encoding for search table.");
+ }
+}
+
+}
+
+#endif