Add .eh_frame_hdr search to Linux unwinder.
This improves the performance of unwinding on DWARF based targets. The 32-bit x86 support for scanning the full eh_frame (CFI_Parser::findFDE) apparently does not work (at least not on Linux). Since the eh_frame_hdr code delegates to that, this still doesn't work for x86 Linux, but it has been tested on x86_64 Linux and aarch64 Android. llvm-svn: 230802
This commit is contained in:
Dan Albert
parent
e3959eb54e
commit
198d366fad
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@ -56,6 +56,9 @@ extern EHTEntry __exidx_start;
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extern EHTEntry __exidx_end;
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#endif // !defined(_LIBUNWIND_IS_BAREMETAL)
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#elif _LIBUNWIND_SUPPORT_DWARF_UNWIND
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#include <link.h>
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#include "EHHeaderParser.hpp"
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#endif // LIBCXXABI_ARM_EHABI
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namespace libunwind {
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@ -132,7 +135,8 @@ public:
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static uint64_t getULEB128(pint_t &addr, pint_t end);
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static int64_t getSLEB128(pint_t &addr, pint_t end);
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pint_t getEncodedP(pint_t &addr, pint_t end, uint8_t encoding);
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pint_t getEncodedP(pint_t &addr, pint_t end, uint8_t encoding,
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pint_t datarelBase = 0);
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bool findFunctionName(pint_t addr, char *buf, size_t bufLen,
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unw_word_t *offset);
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bool findUnwindSections(pint_t targetAddr, UnwindInfoSections &info);
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@ -195,9 +199,9 @@ inline int64_t LocalAddressSpace::getSLEB128(pint_t &addr, pint_t end) {
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return result;
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}
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inline LocalAddressSpace::pint_t LocalAddressSpace::getEncodedP(pint_t &addr,
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pint_t end,
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uint8_t encoding) {
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inline LocalAddressSpace::pint_t
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LocalAddressSpace::getEncodedP(pint_t &addr, pint_t end, uint8_t encoding,
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pint_t datarelBase) {
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pint_t startAddr = addr;
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const uint8_t *p = (uint8_t *)addr;
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pint_t result;
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@ -263,7 +267,12 @@ inline LocalAddressSpace::pint_t LocalAddressSpace::getEncodedP(pint_t &addr,
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_LIBUNWIND_ABORT("DW_EH_PE_textrel pointer encoding not supported");
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break;
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case DW_EH_PE_datarel:
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_LIBUNWIND_ABORT("DW_EH_PE_datarel pointer encoding not supported");
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// DW_EH_PE_datarel is only valid in a few places, so the parameter has a
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// default value of 0, and we abort in the event that someone calls this
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// function with a datarelBase of 0 and DW_EH_PE_datarel encoding.
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if (datarelBase == 0)
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_LIBUNWIND_ABORT("DW_EH_PE_datarel is invalid with a datarelBase of 0");
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result += datarelBase;
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break;
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case DW_EH_PE_funcrel:
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_LIBUNWIND_ABORT("DW_EH_PE_funcrel pointer encoding not supported");
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@ -353,6 +362,64 @@ inline bool LocalAddressSpace::findUnwindSections(pint_t targetAddr,
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info.arm_section, info.arm_section_length);
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if (info.arm_section && info.arm_section_length)
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return true;
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#elif _LIBUNWIND_SUPPORT_DWARF_UNWIND
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#if _LIBUNWIND_SUPPORT_DWARF_INDEX
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struct dl_iterate_cb_data {
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LocalAddressSpace *addressSpace;
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UnwindInfoSections *sects;
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uintptr_t targetAddr;
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};
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dl_iterate_cb_data cb_data = {this, &info, targetAddr};
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int found = dl_iterate_phdr(
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[](struct dl_phdr_info *pinfo, size_t, void *data) -> int {
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auto cbdata = static_cast<dl_iterate_cb_data *>(data);
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size_t object_length;
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bool found_obj = false;
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bool found_hdr = false;
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assert(cbdata);
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assert(cbdata->sects);
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if (cbdata->targetAddr < pinfo->dlpi_addr) {
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return false;
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}
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for (ElfW(Half) i = 0; i < pinfo->dlpi_phnum; i++) {
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const ElfW(Phdr) *phdr = &pinfo->dlpi_phdr[i];
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if (phdr->p_type == PT_LOAD) {
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uintptr_t begin = pinfo->dlpi_addr + phdr->p_vaddr;
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uintptr_t end = begin + phdr->p_memsz;
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if (cbdata->targetAddr >= begin && cbdata->targetAddr < end) {
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cbdata->sects->dso_base = begin;
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object_length = phdr->p_memsz;
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found_obj = true;
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}
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} else if (phdr->p_type == PT_GNU_EH_FRAME) {
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EHHeaderParser<LocalAddressSpace>::EHHeaderInfo hdrInfo;
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uintptr_t eh_frame_hdr_start = pinfo->dlpi_addr + phdr->p_vaddr;
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cbdata->sects->dwarf_index_section = eh_frame_hdr_start;
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cbdata->sects->dwarf_index_section_length = phdr->p_memsz;
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EHHeaderParser<LocalAddressSpace>::decodeEHHdr(
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*cbdata->addressSpace, eh_frame_hdr_start, phdr->p_memsz,
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hdrInfo);
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cbdata->sects->dwarf_section = hdrInfo.eh_frame_ptr;
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found_hdr = true;
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}
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}
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if (found_obj && found_hdr) {
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cbdata->sects->dwarf_section_length = object_length;
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return true;
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} else {
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return false;
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}
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},
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&cb_data);
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return static_cast<bool>(found);
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#else
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#error "_LIBUNWIND_SUPPORT_DWARF_UNWIND requires _LIBUNWIND_SUPPORT_DWARF_INDEX on this platform."
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#endif
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#endif
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return false;
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@ -408,7 +475,8 @@ public:
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pint_t getP(pint_t addr);
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uint64_t getULEB128(pint_t &addr, pint_t end);
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int64_t getSLEB128(pint_t &addr, pint_t end);
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pint_t getEncodedP(pint_t &addr, pint_t end, uint8_t encoding);
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pint_t getEncodedP(pint_t &addr, pint_t end, uint8_t encoding,
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pint_t datarelBase = 0);
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bool findFunctionName(pint_t addr, char *buf, size_t bufLen,
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unw_word_t *offset);
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bool findUnwindSections(pint_t targetAddr, UnwindInfoSections &info);
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@ -0,0 +1,161 @@
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//===------------------------- EHHeaderParser.hpp -------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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//
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//
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// Parses ELF .eh_frame_hdr sections.
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//
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//===----------------------------------------------------------------------===//
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#ifndef __EHHEADERPARSER_HPP__
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#define __EHHEADERPARSER_HPP__
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#include "libunwind.h"
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#include "AddressSpace.hpp"
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#include "DwarfParser.hpp"
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namespace libunwind {
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/// \brief EHHeaderParser does basic parsing of an ELF .eh_frame_hdr section.
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///
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/// See DWARF spec for details:
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/// http://refspecs.linuxbase.org/LSB_3.1.0/LSB-Core-generic/LSB-Core-generic/ehframechpt.html
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///
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template <typename A> class EHHeaderParser {
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public:
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typedef typename A::pint_t pint_t;
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/// Information encoded in the EH frame header.
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struct EHHeaderInfo {
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pint_t eh_frame_ptr;
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size_t fde_count;
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pint_t table;
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uint8_t table_enc;
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};
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static void decodeEHHdr(A &addressSpace, pint_t ehHdrStart, pint_t ehHdrEnd,
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EHHeaderInfo &ehHdrInfo);
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static bool findFDE(A &addressSpace, pint_t pc, pint_t ehHdrStart,
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uint32_t sectionLength,
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typename CFI_Parser<A>::FDE_Info *fdeInfo,
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typename CFI_Parser<A>::CIE_Info *cieInfo);
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private:
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static bool decodeTableEntry(A &addressSpace, pint_t &tableEntry,
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pint_t ehHdrStart, pint_t ehHdrEnd,
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uint8_t tableEnc,
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typename CFI_Parser<A>::FDE_Info *fdeInfo,
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typename CFI_Parser<A>::CIE_Info *cieInfo);
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static size_t getTableEntrySize(uint8_t tableEnc);
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};
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template <typename A>
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void EHHeaderParser<A>::decodeEHHdr(A &addressSpace, pint_t ehHdrStart,
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pint_t ehHdrEnd, EHHeaderInfo &ehHdrInfo) {
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pint_t p = ehHdrStart;
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uint8_t version = addressSpace.get8(p++);
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if (version != 1)
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_LIBUNWIND_ABORT("Unsupported .eh_frame_hdr version");
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uint8_t eh_frame_ptr_enc = addressSpace.get8(p++);
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uint8_t fde_count_enc = addressSpace.get8(p++);
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ehHdrInfo.table_enc = addressSpace.get8(p++);
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ehHdrInfo.eh_frame_ptr =
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addressSpace.getEncodedP(p, ehHdrEnd, eh_frame_ptr_enc, ehHdrStart);
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ehHdrInfo.fde_count =
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addressSpace.getEncodedP(p, ehHdrEnd, fde_count_enc, ehHdrStart);
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ehHdrInfo.table = p;
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}
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template <typename A>
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bool EHHeaderParser<A>::decodeTableEntry(
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A &addressSpace, pint_t &tableEntry, pint_t ehHdrStart, pint_t ehHdrEnd,
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uint8_t tableEnc, typename CFI_Parser<A>::FDE_Info *fdeInfo,
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typename CFI_Parser<A>::CIE_Info *cieInfo) {
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// Have to decode the whole FDE for the PC range anyway, so just throw away
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// the PC start.
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addressSpace.getEncodedP(tableEntry, ehHdrEnd, tableEnc, ehHdrStart);
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pint_t fde =
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addressSpace.getEncodedP(tableEntry, ehHdrEnd, tableEnc, ehHdrStart);
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const char *message =
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CFI_Parser<A>::decodeFDE(addressSpace, fde, fdeInfo, cieInfo);
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if (message != NULL) {
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_LIBUNWIND_DEBUG_LOG("EHHeaderParser::decodeTableEntry: bad fde: %s\n",
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message);
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return false;
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}
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return true;
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}
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template <typename A>
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bool EHHeaderParser<A>::findFDE(A &addressSpace, pint_t pc, pint_t ehHdrStart,
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uint32_t sectionLength,
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typename CFI_Parser<A>::FDE_Info *fdeInfo,
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typename CFI_Parser<A>::CIE_Info *cieInfo) {
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pint_t ehHdrEnd = ehHdrStart + sectionLength;
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EHHeaderParser<A>::EHHeaderInfo hdrInfo;
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EHHeaderParser<A>::decodeEHHdr(addressSpace, ehHdrStart, ehHdrEnd, hdrInfo);
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size_t tableEntrySize = getTableEntrySize(hdrInfo.table_enc);
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pint_t tableEntry;
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size_t low = 0;
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for (size_t len = hdrInfo.fde_count; len > 1;) {
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size_t mid = low + (len / 2);
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tableEntry = hdrInfo.table + mid * tableEntrySize;
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pint_t start = addressSpace.getEncodedP(tableEntry, ehHdrEnd,
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hdrInfo.table_enc, ehHdrStart);
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if (start == pc) {
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low = mid;
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break;
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} else if (start < pc) {
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low = mid;
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len -= (len / 2);
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} else {
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len /= 2;
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}
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}
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tableEntry = hdrInfo.table + low * tableEntrySize;
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if (decodeTableEntry(addressSpace, tableEntry, ehHdrStart, ehHdrEnd,
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hdrInfo.table_enc, fdeInfo, cieInfo)) {
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if (pc >= fdeInfo->pcStart && pc < fdeInfo->pcEnd)
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return true;
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}
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return false;
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}
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template <typename A>
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size_t EHHeaderParser<A>::getTableEntrySize(uint8_t tableEnc) {
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switch (tableEnc & 0x0f) {
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case DW_EH_PE_sdata2:
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case DW_EH_PE_udata2:
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return 4;
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case DW_EH_PE_sdata4:
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case DW_EH_PE_udata4:
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return 8;
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case DW_EH_PE_sdata8:
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case DW_EH_PE_udata8:
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return 16;
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case DW_EH_PE_sleb128:
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case DW_EH_PE_uleb128:
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_LIBUNWIND_ABORT("Can't binary search on variable length encoded data.");
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case DW_EH_PE_omit:
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return 0;
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default:
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_LIBUNWIND_ABORT("Unknown DWARF encoding for search table.");
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}
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}
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}
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#endif
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@ -29,6 +29,7 @@
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#include "CompactUnwinder.hpp"
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#include "config.h"
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#include "DwarfInstructions.hpp"
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#include "EHHeaderParser.hpp"
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#include "libunwind.h"
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#include "Registers.hpp"
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#include "Unwind-EHABI.h"
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@ -829,8 +830,9 @@ bool UnwindCursor<A, R>::getInfoFromDwarfSection(pint_t pc,
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}
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#if _LIBUNWIND_SUPPORT_DWARF_INDEX
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if (!foundFDE && (sects.dwarf_index_section != 0)) {
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// Have eh_frame_hdr section which is index into dwarf section.
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// TO DO: implement index search
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foundFDE = EHHeaderParser<A>::findFDE(
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_addressSpace, pc, sects.dwarf_index_section,
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(uint32_t)sects.dwarf_index_section_length, &fdeInfo, &cieInfo);
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}
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#endif
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if (!foundFDE) {
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@ -83,8 +83,9 @@
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#define _LIBUNWIND_ABORT(msg) assert_rtn(__func__, __FILE__, __LINE__, msg)
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#define _LIBUNWIND_SUPPORT_COMPACT_UNWIND 0
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#define _LIBUNWIND_SUPPORT_DWARF_UNWIND 0
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#define _LIBUNWIND_SUPPORT_DWARF_INDEX 0
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#define _LIBUNWIND_SUPPORT_DWARF_UNWIND !defined(__arm__) || \
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defined(__ARM_DWARF_EH__)
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#define _LIBUNWIND_SUPPORT_DWARF_INDEX _LIBUNWIND_SUPPORT_DWARF_UNWIND
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#endif
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