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Re: [PATCH] gold: Get alignment of uncompressed section from ch_addralign
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Binutils <binutils at sourceware dot org>
- Cc: Cary Coutant <ccoutant at gmail dot com>
- Date: Thu, 29 Nov 2018 09:52:13 -0800
- Subject: Re: [PATCH] gold: Get alignment of uncompressed section from ch_addralign
- References: <20181129133852.19103-1-hjl.tools@gmail.com>
On Thu, Nov 29, 2018 at 5:39 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> The ELF compression header has a field (ch_addralign) that is set to
> the alignment of the uncompressed section. This way the section itself
> can have a different alignment than the decompressed section. Update
> decompress_input_section to get alignment of the decompressed section
> and use it when merging decompressed strings.
>
> PR binutils/23919
> * compressed_output.cc (decompress_input_section): Add a palign
> argument and store ch_addralign in *palign if it isn't NULL.
> * compressed_output.h (decompress_input_section): Add a palign
> argument and default it to NULL.
> * merge.cc (Output_merge_string<Char_type>::do_add_input_section):
> Get addralign from decompress_input_section.
> * object.cc (Object::decompressed_section_contents): Add a palign
> argument and pass it to decompress_input_section.
> * object.h (Object::decompressed_section_contents): Add a palign
> argument and default it to NULL.
This is the updated patch.
--
H.J.
From 1e6a34d7a4e012dacbf0a618810091b5a47c976e Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Thu, 29 Nov 2018 05:29:04 -0800
Subject: [PATCH] gold: Get alignment of uncompressed section from ch_addralign
The ELF compression header has a field (ch_addralign) that is set to
the alignment of the uncompressed section. This way the section itself
can have a different alignment than the decompressed section. Update
decompress_input_section to get alignment of the decompressed section
and use it when merging decompressed strings.
PR binutils/23919
* merge.cc (Output_merge_string<Char_type>::do_add_input_section):
Get addralign from decompressed_section_contents.
* object.cc (build_compressed_section_map): Set info.addralign.
(Object::decompressed_section_contents): Add a palign
argument and store p->second.addralign in *palign if it isn't
NULL.
* object.h (Compressed_section_info): Add addralign.
(section_is_compressed): Add a palign argument, default it
to NULL, store p->second.addralign in *palign if it isn't NULL.
(Object::decompressed_section_contents): Likewise.
* output.cc (Output_section::add_input_section): Get addralign
from section_is_compressed.
---
gold/merge.cc | 8 +++++---
gold/object.cc | 11 +++++++++--
gold/object.h | 8 ++++++--
gold/output.cc | 11 ++++++-----
4 files changed, 26 insertions(+), 12 deletions(-)
diff --git a/gold/merge.cc b/gold/merge.cc
index de00ee9ae9..d7de11789f 100644
--- a/gold/merge.cc
+++ b/gold/merge.cc
@@ -440,9 +440,11 @@ Output_merge_string<Char_type>::do_add_input_section(Relobj* object,
{
section_size_type sec_len;
bool is_new;
+ uint64_t addralign = this->addralign();
const unsigned char* pdata = object->decompressed_section_contents(shndx,
&sec_len,
- &is_new);
+ &is_new,
+ &addralign);
const Char_type* p = reinterpret_cast<const Char_type*>(pdata);
const Char_type* pend = p + sec_len / sizeof(Char_type);
@@ -494,7 +496,7 @@ Output_merge_string<Char_type>::do_add_input_section(Relobj* object,
// aligned, so each string within the section must retain the same
// modulo.
uintptr_t init_align_modulo = (reinterpret_cast<uintptr_t>(pdata)
- & (this->addralign() - 1));
+ & (addralign - 1));
bool has_misaligned_strings = false;
while (p < pend)
@@ -503,7 +505,7 @@ Output_merge_string<Char_type>::do_add_input_section(Relobj* object,
// Within merge input section each string must be aligned.
if (len != 0
- && ((reinterpret_cast<uintptr_t>(p) & (this->addralign() - 1))
+ && ((reinterpret_cast<uintptr_t>(p) & (addralign - 1))
!= init_align_modulo))
has_misaligned_strings = true;
diff --git a/gold/object.cc b/gold/object.cc
index cbeddb9158..473ca4688e 100644
--- a/gold/object.cc
+++ b/gold/object.cc
@@ -751,11 +751,13 @@ build_compressed_section_map(
const unsigned char* contents =
obj->section_contents(i, &len, false);
uint64_t uncompressed_size;
+ Compressed_section_info info;
if (is_zcompressed)
{
// Skip over the ".zdebug" prefix.
name += 7;
uncompressed_size = get_uncompressed_size(contents, len);
+ info.addralign = shdr.get_sh_flags();
}
else
{
@@ -763,8 +765,8 @@ build_compressed_section_map(
name += 6;
elfcpp::Chdr<size, big_endian> chdr(contents);
uncompressed_size = chdr.get_ch_size();
+ info.addralign = chdr.get_ch_addralign();
}
- Compressed_section_info info;
info.size = convert_to_section_size_type(uncompressed_size);
info.flag = shdr.get_sh_flags();
info.contents = NULL;
@@ -3064,7 +3066,8 @@ const unsigned char*
Object::decompressed_section_contents(
unsigned int shndx,
section_size_type* plen,
- bool* is_new)
+ bool* is_new,
+ uint64_t *palign)
{
section_size_type buffer_size;
const unsigned char* buffer = this->do_section_contents(shndx, &buffer_size,
@@ -3091,6 +3094,8 @@ Object::decompressed_section_contents(
{
*plen = uncompressed_size;
*is_new = false;
+ if (palign != NULL)
+ *palign = p->second.addralign;
return p->second.contents;
}
@@ -3112,6 +3117,8 @@ Object::decompressed_section_contents(
// once in this pass.
*plen = uncompressed_size;
*is_new = true;
+ if (palign != NULL)
+ *palign = p->second.addralign;
return uncompressed_data;
}
diff --git a/gold/object.h b/gold/object.h
index 0b786a5471..5574cfbd7c 100644
--- a/gold/object.h
+++ b/gold/object.h
@@ -373,6 +373,7 @@ struct Compressed_section_info
{
section_size_type size;
elfcpp::Elf_Xword flag;
+ uint64_t addralign;
const unsigned char* contents;
};
typedef std::map<unsigned int, Compressed_section_info> Compressed_section_map;
@@ -808,7 +809,8 @@ class Object
bool
section_is_compressed(unsigned int shndx,
- section_size_type* uncompressed_size) const
+ section_size_type* uncompressed_size,
+ elfcpp::Elf_Xword *palign = NULL) const
{
if (this->compressed_sections_ == NULL)
return false;
@@ -818,6 +820,8 @@ class Object
{
if (uncompressed_size != NULL)
*uncompressed_size = p->second.size;
+ if (palign != NULL)
+ *palign = p->second.addralign;
return true;
}
return false;
@@ -828,7 +832,7 @@ class Object
// by the caller.
const unsigned char*
decompressed_section_contents(unsigned int shndx, section_size_type* plen,
- bool* is_cached);
+ bool* is_cached, uint64_t *palign = NULL);
// Discard any buffers of decompressed sections. This is done
// at the end of the Add_symbols task.
diff --git a/gold/output.cc b/gold/output.cc
index 8c71f0217c..24db722214 100644
--- a/gold/output.cc
+++ b/gold/output.cc
@@ -2448,7 +2448,13 @@ Output_section::add_input_section(Layout* layout,
unsigned int reloc_shndx,
bool have_sections_script)
{
+ section_size_type input_section_size = shdr.get_sh_size();
+ section_size_type uncompressed_size;
elfcpp::Elf_Xword addralign = shdr.get_sh_addralign();
+ if (object->section_is_compressed(shndx, &uncompressed_size,
+ &addralign))
+ input_section_size = uncompressed_size;
+
if ((addralign & (addralign - 1)) != 0)
{
object->error(_("invalid alignment %lu for section \"%s\""),
@@ -2498,11 +2504,6 @@ Output_section::add_input_section(Layout* layout,
}
}
- section_size_type input_section_size = shdr.get_sh_size();
- section_size_type uncompressed_size;
- if (object->section_is_compressed(shndx, &uncompressed_size))
- input_section_size = uncompressed_size;
-
off_t offset_in_section;
if (this->has_fixed_layout())
--
2.19.1