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lldb/COFF: Create a separate "section" for the file header

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In an attempt to ensure that every part of the module's memory image is
accounted for, D56537 created a special "container section" spanning the
entire image. While that seemed reasonable at the time (and it still
mostly does), it did create a problem of what to put as the "file size"
of the section, because the image is not continuous on disk, as we
generally assume (which is why I put zero there). Additionally, this
arrangement makes it unclear what kind of permissions should be assigned
to that section (which is what my next patch does).

To get around these, this patch partially reverts D56537, and goes back
to top-level sections. Instead, what I do is create a new "section" for
the object file header, which is also being loaded into memory, though
its not considered to be a section in the strictest sense. This makes it
possible to correctly assign file size section, and we can later assign
permissions to it as well.

Reviewers: amccarth, mstorsjo

Subscribers: lldb-commits

Differential Revision: https://reviews.llvm.org/D69100
This commit is contained in:
Pavel Labath
2019-10-25 21:44:46 +00:00
parent 4c0251da14
commit 73a7a55c0e
3 changed files with 45 additions and 38 deletions
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25
lldb/source/Plugins/ObjectFile/PECOFF/ObjectFilePECOFF.cpp
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@@ -790,13 +790,15 @@ void ObjectFilePECOFF::CreateSections(SectionList &unified_section_list) {
if (module_sp) {
std::lock_guard<std::recursive_mutex> guard(module_sp->GetMutex());
SectionSP image_sp = std::make_shared<Section>(
module_sp, this, ~user_id_t(0), ConstString(), eSectionTypeContainer,
m_coff_header_opt.image_base, m_coff_header_opt.image_size,
/*file_offset*/ 0, /*file_size*/ 0, m_coff_header_opt.sect_alignment,
SectionSP header_sp = std::make_shared<Section>(
module_sp, this, ~user_id_t(0), ConstString("PECOFF header"),
eSectionTypeOther, m_coff_header_opt.image_base,
m_coff_header_opt.header_size,
/*file_offset*/ 0, m_coff_header_opt.header_size,
m_coff_header_opt.sect_alignment,
/*flags*/ 0);
m_sections_up->AddSection(image_sp);
unified_section_list.AddSection(image_sp);
m_sections_up->AddSection(header_sp);
unified_section_list.AddSection(header_sp);
const uint32_t nsects = m_sect_headers.size();
ModuleSP module_sp(GetModule());
@@ -901,15 +903,15 @@ void ObjectFilePECOFF::CreateSections(SectionList &unified_section_list) {
}
SectionSP section_sp(new Section(
image_sp, // Parent section
module_sp, // Module to which this section belongs
this, // Object file to which this section belongs
idx + 1, // Section ID is the 1 based section index.
const_sect_name, // Name of this section
section_type,
m_sect_headers[idx].vmaddr, // File VM address == addresses as
// they are found in the object file
m_sect_headers[idx].vmsize, // VM size in bytes of this section
m_coff_header_opt.image_base +
m_sect_headers[idx].vmaddr, // File VM address == addresses as
// they are found in the object file
m_sect_headers[idx].vmsize, // VM size in bytes of this section
m_sect_headers[idx]
.offset, // Offset to the data for this section in the file
m_sect_headers[idx]
@@ -917,7 +919,8 @@ void ObjectFilePECOFF::CreateSections(SectionList &unified_section_list) {
m_coff_header_opt.sect_alignment, // Section alignment
m_sect_headers[idx].flags)); // Flags for this section
image_sp->GetChildren().AddSection(std::move(section_sp));
m_sections_up->AddSection(section_sp);
unified_section_list.AddSection(section_sp);
}
}
}