From f3870ce80e6b165a5599592ff98a5767e207aa00 Mon Sep 17 00:00:00 2001
From: jdh8d <jdh8d@git.zephyr-software.com>
Date: Wed, 5 Apr 2017 16:42:48 +0000
Subject: [PATCH] bug fixes and first tested version of eh-rewriting.
---
include/ehwrite.h | 2 +-
src/ehwrite.cpp | 354 +++++++++++++++++++++++++++++++++++-----------
src/elfwrite.cpp | 4 +
3 files changed, 277 insertions(+), 83 deletions(-)
diff --git a/include/ehwrite.h b/include/ehwrite.h
index 8a87636..357b288 100644
--- a/include/ehwrite.h
+++ b/include/ehwrite.h
@@ -68,7 +68,7 @@ class EhWriterImpl_t : public EhWriter_t
public:
LSDArepresentation_t(libIRDB::Instruction_t* insn);
void extend(libIRDB::Instruction_t* insn);
- bool canExtend(libIRDB::Instruction_t* insn) const { (void)insn; return true; }
+ bool canExtend(libIRDB::Instruction_t* insn) const;
bool exists() const { return callsite_table.size() > 0; }
struct call_site_t
diff --git a/src/ehwrite.cpp b/src/ehwrite.cpp
index 542c23a..b7f01d0 100644
--- a/src/ehwrite.cpp
+++ b/src/ehwrite.cpp
@@ -222,6 +222,49 @@ EhWriterImpl_t<ptrsize>::FDErepresentation_t::LSDArepresentation_t::LSDArepresen
extend(insn);
}
+
+
+static const auto RelocsEqual=[](const Relocation_t* a, const Relocation_t* b) -> bool
+{
+ return
+ forward_as_tuple(a->GetType(), a->GetOffset(), a->GetWRT(), a->GetAddend()) ==
+ forward_as_tuple(b->GetType(), b->GetOffset(), b->GetWRT(), b->GetAddend());
+};
+
+template <int ptrsize>
+bool EhWriterImpl_t<ptrsize>::FDErepresentation_t::LSDArepresentation_t::canExtend(Instruction_t* insn) const
+{
+ if(insn->GetEhCallSite() == NULL)
+ return true;
+
+ const auto tt_encoding = insn->GetEhCallSite()->GetTTEncoding();
+ // no type table
+ if(tt_encoding==0xff) // DW_EH_PE_omit
+ {
+ // but there's relocs for the type table,
+ // this is a conflict.
+ if(insn->GetEhCallSite()->GetRelocations().size() > 0 )
+ return false;
+ }
+ assert(tt_encoding==0x3 || tt_encoding==0xff); // DW_EH_PE_udata4 or omit
+ const auto tt_entry_size=4;
+
+ const auto mismatch_tt_entry = find_if(
+ insn->GetEhCallSite()->GetRelocations().begin(),
+ insn->GetEhCallSite()->GetRelocations().end(),
+ [&](const Relocation_t* candidate_reloc)
+ {
+ const auto tt_index=candidate_reloc->GetOffset()/tt_entry_size;
+ if(tt_index>=type_table.size())
+ return false;
+ return !RelocsEqual(candidate_reloc, type_table.at(tt_index));
+ }
+ );
+
+ // return true if we found no mismatches
+ return (mismatch_tt_entry == insn->GetEhCallSite()->GetRelocations().end());
+}
+
template <int ptrsize>
void EhWriterImpl_t<ptrsize>::FDErepresentation_t::LSDArepresentation_t::extend(Instruction_t* insn)
{
@@ -261,11 +304,28 @@ void EhWriterImpl_t<ptrsize>::FDErepresentation_t::LSDArepresentation_t::extend(
// for now, this is the only supported reloc type on a EhCallSite
assert(reloc->GetType()=="type_table_entry");
cs.actions.insert(reloc);
- auto tt_it=find(type_table.begin(),type_table.end(), reloc);
+ auto tt_it=find_if(type_table.begin(),type_table.end(),
+ [reloc](const Relocation_t* candidate) { return RelocsEqual(candidate,reloc); });
if(tt_it==type_table.end())
- type_table.push_back(reloc);
+ {
+ const auto tt_encoding = insn->GetEhCallSite()->GetTTEncoding();
+ assert(tt_encoding==0x3); // DW_EH_PE_udata4
+ const auto tt_entry_size=4;
+ const auto tt_index= reloc->GetOffset()/tt_entry_size;
+ if(tt_index>=type_table.size())
+ type_table.resize(tt_index+1);
+ assert(type_table.at(tt_index)==NULL || RelocsEqual(type_table.at(tt_index),reloc));
+ type_table[tt_index]=reloc;
+ }
}
+ // if the instruction has a cleanup, and there are other entries in the action table
+ // add a NULL to the action table to indicate we need to insert a cleanup indicator.
+ // if the cs.actions.size()==0, then we won't need any action list, and we can just set the "pointer"
+ // to the action table entry to be "NULL"
+ if(insn->GetEhCallSite()->GetHasCleanup() && cs.actions.size()>0)
+ cs.actions.insert(NULL);
+
// non-duplciating insert into the action table
auto at_it=find(action_table.begin(),action_table.end(), cs.actions);
if(at_it==action_table.end())
@@ -298,6 +358,10 @@ bool EhWriterImpl_t<ptrsize>::FDErepresentation_t::canExtend(Instruction_t* insn
if(end_addr + new_fde_thresh < insn_addr)
return false;
+ assert(cie);
+ if(!cie->canSupport(insn))
+ return false; // can't change the CIE.
+
return pgm.canExtend(insn->GetEhProgram()->GetFDEProgram()) &&
lsda.canExtend(insn);
@@ -337,11 +401,11 @@ void EhWriterImpl_t<ptrsize>::BuildFDEs()
insn_in_order[this_pair.second]=this_pair.first;
- // build the fdes (and cies/lsdas for this insn, starting with a null fde in case none exist
+ // build the fdes (and cies/lsdas) for this insn, starting with a null fde in case none exist
auto current_fde=(FDErepresentation_t*)NULL;
auto insns_with_frame=0;
-// for_each instruction in program order
+ // for_each instruction in program order
for(const auto& this_pair : insn_in_order)
{
const auto &this_insn=this_pair.second;
@@ -413,39 +477,142 @@ void EhWriterImpl_t<ptrsize>::GenerateEhOutput()
const auto output_lsda=[&](const FDErepresentation_t* fde, ostream& out, const uint32_t lsda_num) -> void
{
const auto lsda=&fde->lsda;
+ out<<"LSDA"<<dec<<lsda_num<<":"<<endl;
+ if(!lsda->exists())
+ {
+ return;
+ }
+
+ // the encoding of the landing pad is done in two parts:
+ // landing_pad=landing_pad_base+landing_pad_offset.
+ // typically, the landing_pad_base is omitted and the fde->start_addr is used instead.
+ // However, sometimes the fde->start_addr is equal to the landing_pad,
+ // which would make the landing_pad_offset 0.
+ // but a landing_pad offset of 0 indicates no landing pad.
+ // To avoid this situation, we first detect it,
+ // then arbitrarily pick (and encode) a landing_pad_base that's
+ // not equal to any landing paad in the call site list.
+ const auto calc_landing_pad_base=[&]() -> uint64_t
+ {
+ // look for a landing pad that happens to match the fde->start_addr
+ const auto lp_base_conflict_it=find_if(
+ lsda->callsite_table.begin(),
+ lsda->callsite_table.end(),
+ [&](const typename FDErepresentation_t::LSDArepresentation_t::call_site_t& candidate)
+ {
+ if(candidate.landing_pad==NULL)
+ return false;
+ const auto lp_addr=zipr_obj.GetLocationMap()->at(candidate.landing_pad);
+ return (lp_addr==fde->start_addr);
+ });
+
+ // if not found, there's no need to adjust the landing pad base address.
+ if(lp_base_conflict_it==lsda->callsite_table.end())
+ return fde->start_addr;
+
+ // we pick an arbitrary landing_pad base by taking the min of all
+ // landing pads (and the fde_start addr), and subtracting 1.
+ const auto min_cs_entry_it=min_element(
+ lsda->callsite_table.begin(),
+ lsda->callsite_table.end(),
+ [&](const typename FDErepresentation_t::LSDArepresentation_t::call_site_t& a , const typename FDErepresentation_t::LSDArepresentation_t::call_site_t &b)
+ {
+ const auto lp_a=a.landing_pad;
+ const auto lp_b=b.landing_pad;
+ if(lp_a && lp_b)
+ {
+ const auto lp_addr_a=zipr_obj.GetLocationMap()->at(lp_a);
+ const auto lp_addr_b=zipr_obj.GetLocationMap()->at(lp_b);
+ return lp_addr_a<lp_addr_b;
+ }
+ if(!lp_a && lp_b)
+ return false;
+ if(!lp_b && lp_a)
+ return true;
+ return false;
+ });
+ const auto &min_cs_entry=*min_cs_entry_it;
+ const auto min_lp_addr=zipr_obj.GetLocationMap()->at(min_cs_entry.landing_pad);
+ const auto min_addr=min(min_lp_addr,fde->start_addr);
+ return min_addr-1;
+
+ };
+
+ const auto landing_pad_base=calc_landing_pad_base();
- const auto output_action=[&](const set<Relocation_t*> acts, const uint32_t act_num) -> void
+ // how to output actions
+ const auto output_action=[&](const set<Relocation_t*> action_reloc_set, const uint32_t act_num) -> void
{
- const auto zero_it=find_if(acts.begin(), acts.end(), [](const Relocation_t* act) { return act->GetWRT()==NULL; });
- const auto has_zero=(zero_it!=acts.end());
+ // determine if cleanup is requested.
+ const auto cleanup_it=find(action_reloc_set.begin(), action_reloc_set.end(), (Relocation_t*)NULL);
+ const auto has_cleanup=(cleanup_it!=action_reloc_set.end());
+
+ // determine if catch all is requested.
+ const auto catch_all_it=find_if(action_reloc_set.begin(), action_reloc_set.end(),
+ [&](const Relocation_t* reloc) { return reloc && reloc->GetWRT()==NULL; });
+ const auto has_catch_all=(catch_all_it!=action_reloc_set.end());
// counter for the element in this action table entry.
- auto act_entry_num=acts.size()-1;
+ auto act_entry_num=action_reloc_set.size()-1;
- if(has_zero)
+ // sanity
+ if(has_cleanup && has_catch_all)
+ // what?
+ assert(0);
+
+ // emit any cleanup first.
+ if(has_cleanup)
{
- const auto zero_reloc=*zero_it;
- const auto tt_it=find(lsda->type_table.begin(), lsda->type_table.end(), zero_reloc);
+ // has to be first
+ assert(act_entry_num==action_reloc_set.size()-1);
+
+ // output entry.
+ out<<"LSDA"<<dec<<lsda_num<<"_act"<<act_num<<"_start_entry"<<act_entry_num<<":"<<endl;
+ out<<" .uleb128 0 #cleanup"<<endl;
+
+ out<<" .uleb128 0 "<<endl; // always comes last in this action_table set
+ act_entry_num--;
+
+ }
+ if(has_catch_all)
+ {
+ const auto catch_all_reloc=*catch_all_it;
+ const auto tt_it=find_if(lsda->type_table.begin(), lsda->type_table.end(),
+ [&](const Relocation_t* candidate) { return RelocsEqual(candidate, catch_all_reloc); });
assert(tt_it != lsda->type_table.end());
const auto tt_index=tt_it-lsda->type_table.begin();
+
out<<"LSDA"<<dec<<lsda_num<<"_act"<<act_num<<"_start_entry"<<act_entry_num<<":"<<endl;
out<<" .uleb128 "<<dec<<1+tt_index<<endl;
- out<<" .uleb128 0 "<<endl;
+
+ if(act_entry_num==action_reloc_set.size()-1)
+ out<<" .uleb128 0 "<<endl;
+ else
+ out<<" .uleb128 LSDA"<<lsda_num<<"_act"<<act_num<<"_start_entry"<<act_entry_num+1<<" - . "<<endl;
act_entry_num--;
-
}
- for(const auto& act : acts)
+ for(const auto& action_reloc : action_reloc_set)
{
- // do nothing for a
- if(act->GetWRT()==NULL) continue;
+ // indicates has_cleanup -- taken care of specially above.
+ if(action_reloc==NULL)
+ {
+ continue;
+ }
+
+ // which indicates has catch all -- taken care of specially above.
+ if(action_reloc->GetWRT()==NULL)
+ {
+ continue;
+ }
- const auto tt_it=find(lsda->type_table.begin(), lsda->type_table.end(), act);
+ const auto tt_it=find_if(lsda->type_table.begin(), lsda->type_table.end(),
+ [action_reloc](const Relocation_t* candidate) { return RelocsEqual(action_reloc,candidate); } );
assert(tt_it != lsda->type_table.end());
const auto tt_index=tt_it-lsda->type_table.begin();
out<<"LSDA"<<dec<<lsda_num<<"_act"<<act_num<<"_start_entry"<<act_entry_num<<""<<":"<<endl;
out<<" .uleb128 "<<dec<<1+tt_index<<endl;
- if(act_entry_num==acts.size()-1)
+ if(act_entry_num==action_reloc_set.size()-1)
out<<" .uleb128 0 "<<endl;
else
out<<" .uleb128 LSDA"<<lsda_num<<"_act"<<act_num<<"_start_entry"<<act_entry_num+1<<" - . "<<endl;
@@ -469,7 +636,7 @@ void EhWriterImpl_t<ptrsize>::GenerateEhOutput()
{
const auto lp_addr=zipr_obj.GetLocationMap()->at(cs.landing_pad);
out<<" # 3) the landing pad, or 0 if none exists."<<endl;
- out<<" .uleb128 0x"<<hex<<lp_addr<<" - 0x"<<hex<<fde->start_addr<<endl;
+ out<<" .uleb128 0x"<<hex<<lp_addr<<" - 0x"<<hex<<landing_pad_base<<endl;
}
else
{
@@ -479,7 +646,8 @@ void EhWriterImpl_t<ptrsize>::GenerateEhOutput()
if(cs.actions.size() > 0 )
{
out<<" # 4) index into action table + 1 -- 0 indicates unwind only"<<endl;
- out<<" .uleb128 1 + LSDA"<<dec<<lsda_num<<"_act"<<cs.action_table_index<<"_start_entry0 - LSDA"<<dec<<lsda_num<<"_action_tab_start"<<endl;
+ out<<" .uleb128 1 + LSDA"<<dec<<lsda_num<<"_act"
+ <<cs.action_table_index<<"_start_entry0 - LSDA"<<dec<<lsda_num<<"_action_tab_start"<<endl;
}
else
{
@@ -490,68 +658,90 @@ void EhWriterImpl_t<ptrsize>::GenerateEhOutput()
};
- out<<"LSDA"<<dec<<lsda_num<<":"<<endl;
- if(!lsda->exists())
- {
- return;
- }
- out<<""<<endl;
- out<<" # 1) encoding of next field "<<endl;
- out<<" .byte 0xff # DW_EH_PE_omit (0xff)"<<endl;
- out<<""<<endl;
- out<<" # 2) landing pad base, if omitted, use FDE start addr"<<endl;
- out<<" # .<fdebasetype> <fdebase> -- omitted. "<<endl;
- out<<""<<endl;
- out<<" # 3) encoding of type table entries"<<endl;
- out<<" .byte 0x3 # DW_EH_PE_udata4"<<endl;
- out<<""<<endl;
- out<<" # 4) type table pointer -- always a uleb128"<<endl;
- out<<" .uleb128 LSDA"<<lsda_num<<"_type_table_end - LSDA"<<lsda_num<<"_tt_ptr_end"<<endl;
- out<<"LSDA"<<lsda_num<<"_tt_ptr_end:"<<endl;
- out<<""<<endl;
- out<<" # 5) call site table encoding"<<endl;
- out<<" .byte 0x1 # DW_EH_PE_uleb128 "<<endl;
- out<<""<<endl;
- out<<" # 6) the length of the call site table"<<endl;
- out<<" .uleb128 LSDA"<<lsda_num<<"_cs_tab_end-LSDA"<<lsda_num<<"_cs_tab_start"<<endl;
- out<<"LSDA"<<lsda_num<<"_cs_tab_start:"<<endl;
-
-
- // output call site table
- auto cs_num=0;
- for(const auto & cs : lsda->callsite_table)
- {
- output_callsite(cs,cs_num++);
- }
- out<<"LSDA"<<dec<<lsda_num<<"_cs_tab_end:"<<endl;
-
- // output action table
- out<<"LSDA"<<dec<<lsda_num<<"_action_tab_start:"<<endl;
- auto act_num=0;
- for(const auto & act : lsda->action_table)
+ const auto output_header=[&]()
{
- output_action(act,act_num++);
- }
- out<<"LSDA"<<dec<<lsda_num<<"_action_tab_end:"<<endl;
-
+ if(landing_pad_base==fde->start_addr)
+ {
+ out<<" # 1) encoding of next field "<<endl;
+ out<<" .byte 0xff # DW_EH_PE_omit (0xff)"<<endl;
+ out<<""<<endl;
+ out<<" # 2) landing pad base, if omitted, use FDE start addr"<<endl;
+ out<<" # .<fdebasetype> <fdebase> -- omitted. "<<endl;
+ }
+ else
+ {
+ out<<" # 1) encoding of next field "<<endl;
+ out<<" .byte 0x1b # DW_EH_PE_pcrel (0x10) |sdata4 (0xb)"<<endl;
+ out<<""<<endl;
+ out<<" # 2) landing pad base, if omitted, use FDE start addr"<<endl;
+ out<<" .int 0x"<<hex<<landing_pad_base<<"- . # as pcrel|sdata4 . "<<endl;
+ }
+ out<<""<<endl;
+ out<<" # 3) encoding of type table entries"<<endl;
+ out<<" .byte 0x3 # DW_EH_PE_udata4"<<endl;
+ out<<""<<endl;
+ out<<" # 4) type table pointer -- always a uleb128"<<endl;
+ out<<" .uleb128 LSDA"<<lsda_num<<"_type_table_end - LSDA"<<lsda_num<<"_tt_ptr_end"<<endl;
+ out<<"LSDA"<<lsda_num<<"_tt_ptr_end:"<<endl;
+ out<<""<<endl;
+ out<<" # 5) call site table encoding"<<endl;
+ out<<" .byte 0x1 # DW_EH_PE_uleb128 "<<endl;
+ out<<""<<endl;
+ out<<" # 6) the length of the call site table"<<endl;
+ out<<" .uleb128 LSDA"<<lsda_num<<"_cs_tab_end-LSDA"<<lsda_num<<"_cs_tab_start"<<endl;
+ out<<"LSDA"<<lsda_num<<"_cs_tab_start:"<<endl;
+ };
- out<<"LSDA"<<dec<<lsda_num<<"_type_table_start:"<<endl;
- for_each( lsda->type_table.rbegin(), lsda->type_table.rend(), [&](const Relocation_t* reloc)
+ const auto output_call_site_table=[&]()
{
- if(reloc->GetWRT()==NULL)
+ // output call site table
+ auto cs_num=0;
+ for(const auto & cs : lsda->callsite_table)
{
- out<<" .int 0x0"<<endl;
+ output_callsite(cs,cs_num++);
}
- else
+ out<<"LSDA"<<dec<<lsda_num<<"_cs_tab_end:"<<endl;
+ };
+ const auto output_action_table=[&]()
+ {
+ // output action table
+ out<<"LSDA"<<dec<<lsda_num<<"_action_tab_start:"<<endl;
+ auto act_num=0;
+ for(const auto & act : lsda->action_table)
{
- const auto scoop=dynamic_cast<DataScoop_t*>(reloc->GetWRT());
- assert(scoop);
- const auto final_addr=scoop->GetStart()->GetVirtualOffset() + reloc->GetAddend();
- out<<" .int 0x"<<hex<<final_addr<<endl;
-
+ output_action(act,act_num++);
}
- });
- out<<"LSDA"<<dec<<lsda_num<<"_type_table_end:"<<endl;
+ out<<"LSDA"<<dec<<lsda_num<<"_action_tab_end:"<<endl;
+ };
+
+ const auto output_type_table=[&]()
+ {
+ out<<"LSDA"<<dec<<lsda_num<<"_type_table_start:"<<endl;
+ for_each( lsda->type_table.rbegin(), lsda->type_table.rend(), [&](const Relocation_t* reloc)
+ {
+ if(reloc->GetWRT()==NULL)
+ {
+ // indicates a catch all
+ out<<" .int 0x0"<<endl;
+ }
+ else
+ {
+ // indicates a catch of a paritcular type
+ const auto scoop=dynamic_cast<DataScoop_t*>(reloc->GetWRT());
+ assert(scoop);
+ const auto final_addr=scoop->GetStart()->GetVirtualOffset() + reloc->GetAddend();
+ out<<" .int 0x"<<hex<<final_addr<<endl;
+
+ }
+ });
+ out<<"LSDA"<<dec<<lsda_num<<"_type_table_end:"<<endl;
+ };
+
+ output_header();
+ output_call_site_table();
+ output_action_table();
+ output_type_table();
+
};
const auto output_cie=[&](const CIErepresentation_t* cie, ostream& out) -> void
{
@@ -757,17 +947,17 @@ void EhWriterImpl_t<ptrsize>::ScoopifyEhOutput()
auto to_scoop=[&](const string &secname)->void
{
- auto sec=ehframe_exe_elfio.sections[secname];
+ const auto &sec=ehframe_exe_elfio.sections[secname];
// if sec is missing, don't scoopify.
if(sec==NULL) return;
- auto data=string(sec->get_data(), sec->get_size());
- auto start_vo=sec->get_address();
- auto start_addr=new AddressID_t(BaseObj_t::NOT_IN_DATABASE, BaseObj_t::NOT_IN_DATABASE, start_vo);
- auto end_vo=sec->get_address()+sec->get_size()-1;
- auto end_addr=new AddressID_t(BaseObj_t::NOT_IN_DATABASE, BaseObj_t::NOT_IN_DATABASE, end_vo);
- auto new_scoop=new DataScoop_t(BaseObj_t::NOT_IN_DATABASE, secname, start_addr,end_addr,NULL,4,false,data);
+ const auto data=string(sec->get_data(), sec->get_size());
+ const auto start_vo=sec->get_address();
+ const auto start_addr=new AddressID_t(BaseObj_t::NOT_IN_DATABASE, BaseObj_t::NOT_IN_DATABASE, start_vo);
+ const auto end_vo=sec->get_address()+sec->get_size()-1;
+ const auto end_addr=new AddressID_t(BaseObj_t::NOT_IN_DATABASE, BaseObj_t::NOT_IN_DATABASE, end_vo);
+ const auto new_scoop=new DataScoop_t(BaseObj_t::NOT_IN_DATABASE, secname, start_addr,end_addr,NULL,4,false,data);
zipr_obj.GetFileIR()->GetAddresses().insert(start_addr);
zipr_obj.GetFileIR()->GetAddresses().insert(end_addr);
diff --git a/src/elfwrite.cpp b/src/elfwrite.cpp
index b75babd..9eb41ba 100644
--- a/src/elfwrite.cpp
+++ b/src/elfwrite.cpp
@@ -781,6 +781,8 @@ void ElfWriterImpl<T_Elf_Ehdr,T_Elf_Phdr,T_Elf_Addr,T_Elf_Shdr,T_Elf_Sym, T_Elf_
{
fseek(fout,0,SEEK_END);
long cur_file_pos=ftell(fout);
+ fseek(fout,cur_file_pos+1,SEEK_SET);
+ cur_file_pos=ftell(fout);
StringTable_t strtab;
@@ -924,10 +926,12 @@ void ElfWriterImpl<T_Elf_Ehdr,T_Elf_Phdr,T_Elf_Addr,T_Elf_Shdr,T_Elf_Sym, T_Elf_
symtab_shdr. sh_entsize =0;
shdrs.push_back(symtab_shdr);
+ cout<<"Writing strtab at filepos="<<hex<<cur_file_pos<<endl;
strtab.Write(fout);
long shdr_file_pos=ftell(fout);
+ cout<<"Writing section headers at filepos="<<hex<<shdr_file_pos<<endl;
fwrite(shdrs.data(), sizeof(T_Elf_Shdr), shdrs.size(), fout);
new_ehdr.e_shentsize=sizeof(T_Elf_Shdr);
--
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