[binutils-gdb] Add x86-64 support for Indirect Branch Tracking (IBT).
Cary Coutant
ccoutant@sourceware.org
Sat Jun 23 07:14:00 GMT 2018
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=750ea5ed38abbda8a6f25e276bff3dfc8e4ce0ee
commit 750ea5ed38abbda8a6f25e276bff3dfc8e4ce0ee
Author: Cary Coutant <ccoutant@gmail.com>
Date: Fri Jun 22 17:28:05 2018 -0700
Add x86-64 support for Indirect Branch Tracking (IBT).
gold/
PR gold/22915
* x86_64.cc (Output_data_plt_x86_64_ibt): New class.
(Target_x86_64::do_make_data_plt): (All instantiations) Check for
IBT feature bit and create IBT PLTs.
Diff:
---
gold/ChangeLog | 7 +
gold/x86_64.cc | 494 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 497 insertions(+), 4 deletions(-)
diff --git a/gold/ChangeLog b/gold/ChangeLog
index f4c6f0a..88ee9a5 100644
--- a/gold/ChangeLog
+++ b/gold/ChangeLog
@@ -1,3 +1,10 @@
+2018-06-23 Cary Coutant <ccoutant@gmail.com>
+
+ PR gold/22915
+ * x86_64.cc (Output_data_plt_x86_64_ibt): New class.
+ (Target_x86_64::do_make_data_plt): (All instantiations) Check for
+ IBT feature bit and create IBT PLTs.
+
2018-06-22 Cary Coutant <ccoutant@gmail.com>
PR gold/22914
diff --git a/gold/x86_64.cc b/gold/x86_64.cc
index a27f84d..9b72597 100644
--- a/gold/x86_64.cc
+++ b/gold/x86_64.cc
@@ -542,6 +542,121 @@ class Output_data_plt_x86_64_bnd : public Output_data_plt_x86_64<64>
static const unsigned char plt_eh_frame_fde[plt_eh_frame_fde_size];
};
+// We use this PLT when Indirect Branch Tracking (IBT) is enabled.
+
+template <int size>
+class Output_data_plt_x86_64_ibt : public Output_data_plt_x86_64<size>
+{
+ public:
+ Output_data_plt_x86_64_ibt(Layout* layout,
+ Output_data_got<64, false>* got,
+ Output_data_got_plt_x86_64* got_plt,
+ Output_data_space* got_irelative)
+ : Output_data_plt_x86_64<size>(layout, plt_entry_size,
+ got, got_plt, got_irelative),
+ aplt_offset_(0)
+ { }
+
+ Output_data_plt_x86_64_ibt(Layout* layout,
+ Output_data_got<64, false>* got,
+ Output_data_got_plt_x86_64* got_plt,
+ Output_data_space* got_irelative,
+ unsigned int plt_count)
+ : Output_data_plt_x86_64<size>(layout, plt_entry_size,
+ got, got_plt, got_irelative,
+ plt_count),
+ aplt_offset_(0)
+ { }
+
+ protected:
+ virtual unsigned int
+ do_get_plt_entry_size() const
+ { return plt_entry_size; }
+
+ // Return the PLT address to use for a global symbol.
+ uint64_t
+ do_address_for_global(const Symbol*);
+
+ // Return the PLT address to use for a local symbol.
+ uint64_t
+ do_address_for_local(const Relobj*, unsigned int symndx);
+
+ virtual void
+ do_add_eh_frame(Layout* layout)
+ {
+ layout->add_eh_frame_for_plt(this,
+ this->plt_eh_frame_cie,
+ this->plt_eh_frame_cie_size,
+ plt_eh_frame_fde,
+ plt_eh_frame_fde_size);
+ }
+
+ virtual void
+ do_fill_first_plt_entry(unsigned char* pov,
+ typename elfcpp::Elf_types<size>::Elf_Addr got_addr,
+ typename elfcpp::Elf_types<size>::Elf_Addr plt_addr);
+
+ virtual unsigned int
+ do_fill_plt_entry(unsigned char* pov,
+ typename elfcpp::Elf_types<size>::Elf_Addr got_address,
+ typename elfcpp::Elf_types<size>::Elf_Addr plt_address,
+ unsigned int got_offset,
+ unsigned int plt_offset,
+ unsigned int plt_index);
+
+ virtual void
+ do_fill_tlsdesc_entry(unsigned char* pov,
+ typename elfcpp::Elf_types<size>::Elf_Addr got_address,
+ typename elfcpp::Elf_types<size>::Elf_Addr plt_address,
+ typename elfcpp::Elf_types<size>::Elf_Addr got_base,
+ unsigned int tlsdesc_got_offset,
+ unsigned int plt_offset);
+
+ void
+ fill_aplt_entry(unsigned char* pov,
+ typename elfcpp::Elf_types<size>::Elf_Addr got_address,
+ typename elfcpp::Elf_types<size>::Elf_Addr plt_address,
+ unsigned int got_offset,
+ unsigned int plt_offset,
+ unsigned int plt_index);
+
+ private:
+ // Set the final size.
+ void
+ set_final_data_size();
+
+ // Write out the BND PLT data.
+ void
+ do_write(Output_file*);
+
+ // Offset of the Additional PLT (if using -z bndplt).
+ unsigned int aplt_offset_;
+
+ // The size of an entry in the PLT.
+ static const int plt_entry_size = 16;
+
+ // The size of an entry in the additional PLT.
+ static const int aplt_entry_size = 16;
+
+ // The first entry in the PLT.
+ // From the AMD64 ABI: "Unlike Intel386 ABI, this ABI uses the same
+ // procedure linkage table for both programs and shared objects."
+ static const unsigned char first_plt_entry[plt_entry_size];
+
+ // Other entries in the PLT for an executable.
+ static const unsigned char plt_entry[plt_entry_size];
+
+ // Entries in the additional PLT.
+ static const unsigned char aplt_entry[aplt_entry_size];
+
+ // The reserved TLSDESC entry in the PLT for an executable.
+ static const unsigned char tlsdesc_plt_entry[plt_entry_size];
+
+ // The .eh_frame unwind information for the PLT.
+ static const int plt_eh_frame_fde_size = 32;
+ static const unsigned char plt_eh_frame_fde[plt_eh_frame_fde_size];
+};
+
template<int size>
class Lazy_view
{
@@ -2101,6 +2216,242 @@ Output_data_plt_x86_64_bnd::do_fill_tlsdesc_entry(
+ 13)));
}
+// Return the APLT address to use for a global symbol (for IBT).
+
+template<int size>
+uint64_t
+Output_data_plt_x86_64_ibt<size>::do_address_for_global(const Symbol* gsym)
+{
+ uint64_t offset = this->aplt_offset_;
+ // Convert the PLT offset into an APLT offset.
+ unsigned int plt_offset = gsym->plt_offset();
+ if (gsym->type() == elfcpp::STT_GNU_IFUNC
+ && gsym->can_use_relative_reloc(false))
+ offset += this->regular_count() * aplt_entry_size;
+ else
+ plt_offset -= plt_entry_size;
+ plt_offset = plt_offset / (plt_entry_size / aplt_entry_size);
+ return this->address() + offset + plt_offset;
+}
+
+// Return the PLT address to use for a local symbol. These are always
+// IRELATIVE relocs.
+
+template<int size>
+uint64_t
+Output_data_plt_x86_64_ibt<size>::do_address_for_local(const Relobj* object,
+ unsigned int r_sym)
+{
+ // Convert the PLT offset into an APLT offset.
+ unsigned int plt_offset = ((object->local_plt_offset(r_sym) - plt_entry_size)
+ / (plt_entry_size / aplt_entry_size));
+ return (this->address()
+ + this->aplt_offset_
+ + this->regular_count() * aplt_entry_size
+ + plt_offset);
+}
+
+// Set the final size.
+
+template<int size>
+void
+Output_data_plt_x86_64_ibt<size>::set_final_data_size()
+{
+ // Number of regular and IFUNC PLT entries.
+ unsigned int count = this->entry_count();
+ // Count the first entry and the TLSDESC entry, if present.
+ unsigned int extra = this->has_tlsdesc_entry() ? 2 : 1;
+ unsigned int plt_size = (count + extra) * plt_entry_size;
+ // Offset of the APLT.
+ this->aplt_offset_ = plt_size;
+ // Size of the APLT.
+ plt_size += count * aplt_entry_size;
+ this->set_data_size(plt_size);
+}
+
+// The first entry in the IBT PLT.
+
+template<>
+const unsigned char
+Output_data_plt_x86_64_ibt<32>::first_plt_entry[plt_entry_size] =
+{
+ // MPX isn't supported for x32, so we don't need the BND prefix.
+ // From AMD64 ABI Draft 0.98, page 76
+ 0xff, 0x35, // pushq contents of memory address
+ 0, 0, 0, 0, // replaced with address of .got + 8
+ 0xff, 0x25, // jmp indirect
+ 0, 0, 0, 0, // replaced with address of .got + 16
+ 0x90, 0x90, 0x90, 0x90 // noop (x4)
+};
+
+template<>
+const unsigned char
+Output_data_plt_x86_64_ibt<64>::first_plt_entry[plt_entry_size] =
+{
+ // Use the BND prefix so that IBT is compatible with MPX.
+ 0xff, 0x35, // pushq contents of memory address
+ 0, 0, 0, 0, // replaced with address of .got + 8
+ 0xf2, 0xff, 0x25, // bnd jmp indirect
+ 0, 0, 0, 0, // replaced with address of .got + 16
+ 0x0f, 0x1f, 0x00 // nop
+};
+
+template<int size>
+void
+Output_data_plt_x86_64_ibt<size>::do_fill_first_plt_entry(
+ unsigned char* pov,
+ typename elfcpp::Elf_types<size>::Elf_Addr got_address,
+ typename elfcpp::Elf_types<size>::Elf_Addr plt_address)
+{
+ // Offsets to the addresses needing relocation.
+ const unsigned int roff1 = 2;
+ const unsigned int roff2 = (size == 32) ? 8 : 9;
+
+ memcpy(pov, first_plt_entry, plt_entry_size);
+ // We do a jmp relative to the PC at the end of this instruction.
+ elfcpp::Swap_unaligned<32, false>::writeval(pov + roff1,
+ (got_address + 8
+ - (plt_address + roff1 + 4)));
+ elfcpp::Swap<32, false>::writeval(pov + roff2,
+ (got_address + 16
+ - (plt_address + roff2 + 4)));
+}
+
+// Subsequent entries in the IBT PLT.
+
+template<>
+const unsigned char
+Output_data_plt_x86_64_ibt<32>::plt_entry[plt_entry_size] =
+{
+ // From AMD64 ABI Draft 1.0-rc1, Chapter 13.
+ 0xf3, 0x0f, 0x1e, 0xfa, // endbr64
+ 0x68, // pushq immediate
+ 0, 0, 0, 0, // replaced with offset into relocation table
+ 0xe9, // jmpq relative
+ 0, 0, 0, 0, // replaced with offset to start of .plt
+ 0x90, 0x90 // nop
+};
+
+template<>
+const unsigned char
+Output_data_plt_x86_64_ibt<64>::plt_entry[plt_entry_size] =
+{
+ // From AMD64 ABI Draft 1.0-rc1, Chapter 13.
+ 0xf3, 0x0f, 0x1e, 0xfa, // endbr64
+ 0x68, // pushq immediate
+ 0, 0, 0, 0, // replaced with offset into relocation table
+ 0xf2, 0xe9, // bnd jmpq relative
+ 0, 0, 0, 0, // replaced with offset to start of .plt
+ 0x90 // nop
+};
+
+// Entries in the IBT Additional PLT.
+
+template<>
+const unsigned char
+Output_data_plt_x86_64_ibt<32>::aplt_entry[aplt_entry_size] =
+{
+ // From AMD64 ABI Draft 1.0-rc1, Chapter 13.
+ 0xf3, 0x0f, 0x1e, 0xfa, // endbr64
+ 0xff, 0x25, // jmpq indirect
+ 0, 0, 0, 0, // replaced with address of symbol in .got
+ 0x0f, 0x1f, 0x04, 0x00, // nop
+ 0x90, 0x90 // nop
+};
+
+template<>
+const unsigned char
+Output_data_plt_x86_64_ibt<64>::aplt_entry[aplt_entry_size] =
+{
+ // From AMD64 ABI Draft 1.0-rc1, Chapter 13.
+ 0xf3, 0x0f, 0x1e, 0xfa, // endbr64
+ 0xf2, 0xff, 0x25, // bnd jmpq indirect
+ 0, 0, 0, 0, // replaced with address of symbol in .got
+ 0x0f, 0x1f, 0x04, 0x00, // nop
+ 0x90, // nop
+};
+
+template<int size>
+unsigned int
+Output_data_plt_x86_64_ibt<size>::do_fill_plt_entry(
+ unsigned char* pov,
+ typename elfcpp::Elf_types<size>::Elf_Addr,
+ typename elfcpp::Elf_types<size>::Elf_Addr,
+ unsigned int,
+ unsigned int plt_offset,
+ unsigned int plt_index)
+{
+ // Offsets to the addresses needing relocation.
+ const unsigned int roff1 = 5;
+ const unsigned int roff2 = (size == 32) ? 10 : 11;
+
+ memcpy(pov, plt_entry, plt_entry_size);
+ elfcpp::Swap_unaligned<32, false>::writeval(pov + roff1, plt_index);
+ elfcpp::Swap<32, false>::writeval(pov + roff2, -(plt_offset + roff2 + 4));
+ return 0;
+}
+
+template<int size>
+void
+Output_data_plt_x86_64_ibt<size>::fill_aplt_entry(
+ unsigned char* pov,
+ typename elfcpp::Elf_types<size>::Elf_Addr got_address,
+ typename elfcpp::Elf_types<size>::Elf_Addr plt_address,
+ unsigned int got_offset,
+ unsigned int plt_offset,
+ unsigned int plt_index)
+{
+ // Offset to the address needing relocation.
+ const unsigned int roff = (size == 32) ? 6 : 7;
+
+ // Check PC-relative offset overflow in PLT entry.
+ uint64_t plt_got_pcrel_offset = (got_address + got_offset
+ - (plt_address + plt_offset + roff + 4));
+ if (Bits<32>::has_overflow(plt_got_pcrel_offset))
+ gold_error(_("PC-relative offset overflow in APLT entry %d"),
+ plt_index + 1);
+
+ memcpy(pov, aplt_entry, aplt_entry_size);
+ elfcpp::Swap_unaligned<32, false>::writeval(pov + roff, plt_got_pcrel_offset);
+}
+
+// The reserved TLSDESC entry in the IBT PLT for an executable.
+
+template<int size>
+const unsigned char
+Output_data_plt_x86_64_ibt<size>::tlsdesc_plt_entry[plt_entry_size] =
+{
+ // From Alexandre Oliva, "Thread-Local Storage Descriptors for IA32
+ // and AMD64/EM64T", Version 0.9.4 (2005-10-10).
+ 0xff, 0x35, // pushq x(%rip)
+ 0, 0, 0, 0, // replaced with address of linkmap GOT entry (at PLTGOT + 8)
+ 0xf2, 0xff, 0x25, // jmpq *y(%rip)
+ 0, 0, 0, 0, // replaced with offset of reserved TLSDESC_GOT entry
+ 0x0f, 0x1f, 0 // nop
+};
+
+template<int size>
+void
+Output_data_plt_x86_64_ibt<size>::do_fill_tlsdesc_entry(
+ unsigned char* pov,
+ typename elfcpp::Elf_types<size>::Elf_Addr got_address,
+ typename elfcpp::Elf_types<size>::Elf_Addr plt_address,
+ typename elfcpp::Elf_types<size>::Elf_Addr got_base,
+ unsigned int tlsdesc_got_offset,
+ unsigned int plt_offset)
+{
+ memcpy(pov, tlsdesc_plt_entry, plt_entry_size);
+ elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
+ (got_address + 8
+ - (plt_address + plt_offset
+ + 6)));
+ elfcpp::Swap_unaligned<32, false>::writeval(pov + 9,
+ (got_base
+ + tlsdesc_got_offset
+ - (plt_address + plt_offset
+ + 13)));
+}
+
// The .eh_frame unwind information for the PLT.
template<int size>
@@ -2179,6 +2530,35 @@ Output_data_plt_x86_64_bnd::plt_eh_frame_fde[plt_eh_frame_fde_size] =
elfcpp::DW_CFA_nop
};
+// The .eh_frame unwind information for the BND PLT.
+template<int size>
+const unsigned char
+Output_data_plt_x86_64_ibt<size>::plt_eh_frame_fde[plt_eh_frame_fde_size] =
+{
+ 0, 0, 0, 0, // Replaced with offset to .plt.
+ 0, 0, 0, 0, // Replaced with size of .plt.
+ 0, // Augmentation size.
+ elfcpp::DW_CFA_def_cfa_offset, 16, // DW_CFA_def_cfa_offset: 16.
+ elfcpp::DW_CFA_advance_loc + 6, // Advance 6 to __PLT__ + 6.
+ elfcpp::DW_CFA_def_cfa_offset, 24, // DW_CFA_def_cfa_offset: 24.
+ elfcpp::DW_CFA_advance_loc + 10, // Advance 10 to __PLT__ + 16.
+ elfcpp::DW_CFA_def_cfa_expression, // DW_CFA_def_cfa_expression.
+ 11, // Block length.
+ elfcpp::DW_OP_breg7, 8, // Push %rsp + 8.
+ elfcpp::DW_OP_breg16, 0, // Push %rip.
+ elfcpp::DW_OP_lit15, // Push 0xf.
+ elfcpp::DW_OP_and, // & (%rip & 0xf).
+ elfcpp::DW_OP_lit9, // Push 9.
+ elfcpp::DW_OP_ge, // >= ((%rip & 0xf) >= 9)
+ elfcpp::DW_OP_lit3, // Push 3.
+ elfcpp::DW_OP_shl, // << (((%rip & 0xf) >= 9) << 3)
+ elfcpp::DW_OP_plus, // + ((((%rip&0xf)>=9)<<3)+%rsp+8
+ elfcpp::DW_CFA_nop, // Align to 32 bytes.
+ elfcpp::DW_CFA_nop,
+ elfcpp::DW_CFA_nop,
+ elfcpp::DW_CFA_nop
+};
+
// Write out the PLT. This uses the hand-coded instructions above,
// and adjusts them as needed. This is specified by the AMD64 ABI.
@@ -2340,7 +2720,102 @@ Output_data_plt_x86_64_bnd::do_write(Output_file* of)
plt_offset += aplt_entry_size,
got_offset += 8)
{
+ // Set and adjust the APLT entry.
+ this->fill_aplt_entry(pov, got_address, plt_address, got_offset,
+ plt_offset, plt_index);
+ }
+
+ gold_assert(static_cast<section_size_type>(pov - oview) == oview_size);
+ gold_assert(static_cast<section_size_type>(got_pov - got_view) == got_size);
+
+ of->write_output_view(offset, oview_size, oview);
+ of->write_output_view(got_file_offset, got_size, got_view);
+}
+
+// Write out the IBT PLT.
+
+template<int size>
+void
+Output_data_plt_x86_64_ibt<size>::do_write(Output_file* of)
+{
+ const off_t offset = this->offset();
+ const section_size_type oview_size =
+ convert_to_section_size_type(this->data_size());
+ unsigned char* const oview = of->get_output_view(offset, oview_size);
+
+ Output_data_got<64, false>* got = this->got();
+ Output_data_got_plt_x86_64* got_plt = this->got_plt();
+ Output_data_space* got_irelative = this->got_irelative();
+
+ const off_t got_file_offset = got_plt->offset();
+ gold_assert(parameters->incremental_update()
+ || (got_file_offset + got_plt->data_size()
+ == got_irelative->offset()));
+ const section_size_type got_size =
+ convert_to_section_size_type(got_plt->data_size()
+ + got_irelative->data_size());
+ unsigned char* const got_view = of->get_output_view(got_file_offset,
+ got_size);
+
+ unsigned char* pov = oview;
+
+ // The base address of the .plt section.
+ elfcpp::Elf_types<64>::Elf_Addr plt_address = this->address();
+ // The base address of the .got section.
+ elfcpp::Elf_types<64>::Elf_Addr got_base = got->address();
+ // The base address of the PLT portion of the .got section,
+ // which is where the GOT pointer will point, and where the
+ // three reserved GOT entries are located.
+ elfcpp::Elf_types<64>::Elf_Addr got_address = got_plt->address();
+
+ this->fill_first_plt_entry(pov, got_address, plt_address);
+ pov += plt_entry_size;
+
+ // The first three entries in the GOT are reserved, and are written
+ // by Output_data_got_plt_x86_64::do_write.
+ unsigned char* got_pov = got_view + 24;
+
+ unsigned int plt_offset = plt_entry_size;
+ unsigned int got_offset = 24;
+ const unsigned int count = this->entry_count();
+ for (unsigned int plt_index = 0;
+ plt_index < count;
+ ++plt_index,
+ pov += plt_entry_size,
+ got_pov += 8,
+ plt_offset += plt_entry_size,
+ got_offset += 8)
+ {
// Set and adjust the PLT entry itself.
+ unsigned int lazy_offset = this->fill_plt_entry(pov,
+ got_address, plt_address,
+ got_offset, plt_offset,
+ plt_index);
+
+ // Set the entry in the GOT.
+ elfcpp::Swap<64, false>::writeval(got_pov,
+ plt_address + plt_offset + lazy_offset);
+ }
+
+ if (this->has_tlsdesc_entry())
+ {
+ // Set and adjust the reserved TLSDESC PLT entry.
+ unsigned int tlsdesc_got_offset = this->get_tlsdesc_got_offset();
+ this->fill_tlsdesc_entry(pov, got_address, plt_address, got_base,
+ tlsdesc_got_offset, plt_offset);
+ pov += this->get_plt_entry_size();
+ }
+
+ // Write the additional PLT.
+ got_offset = 24;
+ for (unsigned int plt_index = 0;
+ plt_index < count;
+ ++plt_index,
+ pov += aplt_entry_size,
+ plt_offset += aplt_entry_size,
+ got_offset += 8)
+ {
+ // Set and adjust the APLT entry.
this->fill_aplt_entry(pov, got_address, plt_address, got_offset,
plt_offset, plt_index);
}
@@ -2388,6 +2863,9 @@ Target_x86_64<32>::do_make_data_plt(Layout* layout,
Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative)
{
+ if (this->feature_1_ & elfcpp::GNU_PROPERTY_X86_FEATURE_1_IBT)
+ return new Output_data_plt_x86_64_ibt<32>(layout, got, got_plt,
+ got_irelative);
return new Output_data_plt_x86_64_standard<32>(layout, got, got_plt,
got_irelative);
}
@@ -2399,7 +2877,10 @@ Target_x86_64<64>::do_make_data_plt(Layout* layout,
Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative)
{
- if (parameters->options().bndplt())
+ if (this->feature_1_ & elfcpp::GNU_PROPERTY_X86_FEATURE_1_IBT)
+ return new Output_data_plt_x86_64_ibt<64>(layout, got, got_plt,
+ got_irelative);
+ else if (parameters->options().bndplt())
return new Output_data_plt_x86_64_bnd(layout, got, got_plt,
got_irelative);
else
@@ -2415,9 +2896,11 @@ Target_x86_64<32>::do_make_data_plt(Layout* layout,
Output_data_space* got_irelative,
unsigned int plt_count)
{
+ if (this->feature_1_ & elfcpp::GNU_PROPERTY_X86_FEATURE_1_IBT)
+ return new Output_data_plt_x86_64_ibt<32>(layout, got, got_plt,
+ got_irelative, plt_count);
return new Output_data_plt_x86_64_standard<32>(layout, got, got_plt,
- got_irelative,
- plt_count);
+ got_irelative, plt_count);
}
template<>
@@ -2428,7 +2911,10 @@ Target_x86_64<64>::do_make_data_plt(Layout* layout,
Output_data_space* got_irelative,
unsigned int plt_count)
{
- if (parameters->options().bndplt())
+ if (this->feature_1_ & elfcpp::GNU_PROPERTY_X86_FEATURE_1_IBT)
+ return new Output_data_plt_x86_64_ibt<64>(layout, got, got_plt,
+ got_irelative, plt_count);
+ else if (parameters->options().bndplt())
return new Output_data_plt_x86_64_bnd(layout, got, got_plt,
got_irelative, plt_count);
else
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