From 935e887746227322222835cd002ec486f9f31402 Mon Sep 17 00:00:00 2001 From: Ian Lance Taylor Date: Thu, 14 Feb 2008 02:40:15 +0000 Subject: [PATCH] Align FDE and CIE lengths as needed. --- gold/ehframe.cc | 58 ++++++++++++++++++++++++++++++++++++++++++--------------- gold/ehframe.h | 14 ++++++++------ 2 files changed, 51 insertions(+), 21 deletions(-) diff --git a/gold/ehframe.cc b/gold/ehframe.cc index 80fd859..8306f51 100644 --- a/gold/ehframe.cc +++ b/gold/ehframe.cc @@ -336,21 +336,28 @@ Eh_frame_hdr::get_fde_addresses(Output_file* of, // Write the FDE to OVIEW starting at OFFSET. CIE_OFFSET is the // offset of the CIE in OVIEW. FDE_ENCODING is the encoding, from the -// CIE. Record the FDE pc for EH_FRAME_HDR. Return the new offset. +// CIE. ADDRALIGN is the required alignment. Record the FDE pc for +// EH_FRAME_HDR. Return the new offset. template section_offset_type Fde::write(unsigned char* oview, section_offset_type offset, - section_offset_type cie_offset, unsigned char fde_encoding, - Eh_frame_hdr* eh_frame_hdr) + unsigned int addralign, section_offset_type cie_offset, + unsigned char fde_encoding, Eh_frame_hdr* eh_frame_hdr) { + gold_assert((offset & (addralign - 1)) == 0); + size_t length = this->contents_.length(); + // We add 8 when getting the aligned length to account for the + // length word and the CIE offset. + size_t aligned_full_length = align_address(length + 8, addralign); + // Write the length of the FDE as a 32-bit word. The length word // does not include the four bytes of the length word itself, but it // does include the offset to the CIE. elfcpp::Swap<32, big_endian>::writeval(oview + offset, - length + 4); + aligned_full_length - 4); // Write the offset to the CIE as a 32-bit word. This is the // difference between the address of the offset word itself and the @@ -363,11 +370,14 @@ Fde::write(unsigned char* oview, section_offset_type offset, // will later be applied to the FDE data. memcpy(oview + offset + 8, this->contents_.data(), length); + if (aligned_full_length > length + 8) + memset(oview + offset + length + 8, 0, aligned_full_length - (length + 8)); + // Tell the exception frame header about this FDE. if (eh_frame_hdr != NULL) eh_frame_hdr->record_fde(offset, fde_encoding); - return offset + length + 8; + return offset + aligned_full_length; } // Class Cie. @@ -390,13 +400,15 @@ Cie::set_output_offset(section_offset_type output_offset, Merge_map* merge_map) { size_t length = this->contents_.length(); - gold_assert((length & (addralign - 1)) == 0); + // Add 4 for length and 4 for zero CIE identifier tag. length += 8; merge_map->add_mapping(this->object_, this->shndx_, this->input_offset_, length, output_offset); + length = align_address(length, addralign); + for (std::vector::const_iterator p = this->fdes_.begin(); p != this->fdes_.end(); ++p) @@ -404,7 +416,7 @@ Cie::set_output_offset(section_offset_type output_offset, (*p)->add_mapping(output_offset + length, merge_map); size_t fde_length = (*p)->length(); - gold_assert((fde_length & (addralign - 1)) == 0); + fde_length = align_address(fde_length, addralign); length += fde_length; } @@ -412,35 +424,48 @@ Cie::set_output_offset(section_offset_type output_offset, } // Write the CIE to OVIEW starting at OFFSET. EH_FRAME_HDR is for FDE -// recording. Return the new offset. +// recording. Round up the bytes to ADDRALIGN. Return the new +// offset. template section_offset_type Cie::write(unsigned char* oview, section_offset_type offset, - Eh_frame_hdr* eh_frame_hdr) + unsigned int addralign, Eh_frame_hdr* eh_frame_hdr) { + gold_assert((offset & (addralign - 1)) == 0); + section_offset_type cie_offset = offset; size_t length = this->contents_.length(); + // We add 8 when getting the aligned length to account for the + // length word and the CIE tag. + size_t aligned_full_length = align_address(length + 8, addralign); + // Write the length of the CIE as a 32-bit word. The length word // does not include the four bytes of the length word itself. - elfcpp::Swap<32, big_endian>::writeval(oview + offset, length + 4); + elfcpp::Swap<32, big_endian>::writeval(oview + offset, + aligned_full_length - 4); // Write the tag which marks this as a CIE: a 32-bit zero. elfcpp::Swap<32, big_endian>::writeval(oview + offset + 4, 0); // Write out the CIE data. memcpy(oview + offset + 8, this->contents_.data(), length); - offset += length + 8; + + if (aligned_full_length > length + 8) + memset(oview + offset + length + 8, 0, aligned_full_length - (length + 8)); + + offset += aligned_full_length; // Write out the associated FDEs. unsigned char fde_encoding = this->fde_encoding_; for (std::vector::const_iterator p = this->fdes_.begin(); p != this->fdes_.end(); ++p) - offset = (*p)->write(oview, offset, cie_offset, - fde_encoding, eh_frame_hdr); + offset = (*p)->write(oview, offset, addralign, + cie_offset, fde_encoding, + eh_frame_hdr); return offset; } @@ -1100,16 +1125,19 @@ template void Eh_frame::do_sized_write(unsigned char* oview) { + unsigned int addralign = this->addralign(); section_offset_type o = 0; for (Unmergeable_cie_offsets::iterator p = this->unmergeable_cie_offsets_.begin(); p != this->unmergeable_cie_offsets_.end(); ++p) - o = (*p)->write(oview, o, this->eh_frame_hdr_); + o = (*p)->write(oview, o, addralign, + this->eh_frame_hdr_); for (Cie_offsets::iterator p = this->cie_offsets_.begin(); p != this->cie_offsets_.end(); ++p) - o = (*p)->write(oview, o, this->eh_frame_hdr_); + o = (*p)->write(oview, o, addralign, + this->eh_frame_hdr_); } #ifdef HAVE_TARGET_32_LITTLE diff --git a/gold/ehframe.h b/gold/ehframe.h index 2f45b23..cf3b738 100644 --- a/gold/ehframe.h +++ b/gold/ehframe.h @@ -184,13 +184,14 @@ class Fde } // Write the FDE to OVIEW starting at OFFSET. FDE_ENCODING is the - // encoding, from the CIE. Record the FDE in EH_FRAME_HDR. Return - // the new offset. + // encoding, from the CIE. Round up the bytes to ADDRALIGN if + // necessary. Record the FDE in EH_FRAME_HDR. Return the new + // offset. template section_offset_type write(unsigned char* oview, section_offset_type offset, - section_offset_type cie_offset, unsigned char fde_encoding, - Eh_frame_hdr* eh_frame_hdr); + unsigned int addralign, section_offset_type cie_offset, + unsigned char fde_encoding, Eh_frame_hdr* eh_frame_hdr); private: // The object in which this FDE was seen. @@ -253,11 +254,12 @@ class Cie Merge_map*); // Write the CIE to OVIEW starting at OFFSET. EH_FRAME_HDR is the - // exception frame header for FDE recording. Return the new offset. + // exception frame header for FDE recording. Round up the bytes to + // ADDRALIGN. Return the new offset. template section_offset_type write(unsigned char* oview, section_offset_type offset, - Eh_frame_hdr* eh_frame_hdr); + unsigned int addralign, Eh_frame_hdr* eh_frame_hdr); friend bool operator<(const Cie&, const Cie&); friend bool operator==(const Cie&, const Cie&); -- 2.7.4