[llvm-branch-commits] [llvm] cefe687 - [llvm-objcopy][COFF] Fix section name encoding
Tom Stellard via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Tue Feb 22 11:19:16 PST 2022
Author: Nicolas Miller
Date: 2022-02-22T11:11:28-08:00
New Revision: cefe6876d6e55ee8d544ab98216251ddd35ee7a9
URL: https://github.com/llvm/llvm-project/commit/cefe6876d6e55ee8d544ab98216251ddd35ee7a9
DIFF: https://github.com/llvm/llvm-project/commit/cefe6876d6e55ee8d544ab98216251ddd35ee7a9.diff
LOG: [llvm-objcopy][COFF] Fix section name encoding
The section name encoding for `llvm-objcopy` had two main issues, the
first is that the size used for the `snprintf` in the original code is
incorrect because `snprintf` adds a null byte, so this code was only
able to encode offsets of 6 digits - `/`, `\0` and 6 digits of the
offset - rather than the 7 digits it should support.
And the second part is that it didn't support the base64 encoding for
offsets larger than 7 digits.
This issue specifically showed up when using the `clang-offload-bundler`
with a binary containing a lot of symbols/sections, since it uses
`llvm-objcopy` to add the sections containing the offload code.
Reviewed By: jhenderson
Differential Revision: https://reviews.llvm.org/D118692
(cherry picked from commit ddf528b7a092fd24647d7c6186ece7392c92de92)
Added:
llvm/test/tools/llvm-objcopy/COFF/section-name-encoding.s
Modified:
llvm/tools/llvm-objcopy/CMakeLists.txt
llvm/tools/llvm-objcopy/COFF/Writer.cpp
llvm/tools/llvm-objcopy/COFF/Writer.h
Removed:
################################################################################
diff --git a/llvm/test/tools/llvm-objcopy/COFF/section-name-encoding.s b/llvm/test/tools/llvm-objcopy/COFF/section-name-encoding.s
new file mode 100644
index 000000000000..bd8b7c1bcf96
--- /dev/null
+++ b/llvm/test/tools/llvm-objcopy/COFF/section-name-encoding.s
@@ -0,0 +1,95 @@
+## Check that COFF section names of sections added by llvm-objcopy are properly
+## encoded.
+##
+## Encodings for
diff erent name lengths and string table index:
+## [0, 8]: raw name
+## (8, 999999]: base 10 string table index (/9999999)
+## (999999, 0xFFFFFFFF]: base 64 string table index (##AAAAAA)
+##
+## Note: the names in the string table will be sorted in reverse
+## lexicographical order. Use a suffix letter (z, y, x, ...) to
+## get the preferred ordering of names in the test.
+##
+# REQUIRES: x86-registered-target
+##
+# RUN: echo DEADBEEF > %t.sec
+# RUN: llvm-mc -triple x86_64-pc-win32 -filetype=obj %s -o %t.obj
+# RUN: llvm-objcopy --add-section=s1234567=%t.sec \
+# RUN: --add-section=s1234567z=%t.sec \
+# RUN: --add-section=sevendigitx=%t.sec \
+# RUN: --add-section=doubleslashv=%t.sec \
+# RUN: %t.obj %t
+# RUN: llvm-readobj --sections %t | FileCheck %s
+
+## Raw encoding
+
+# CHECK: Section {
+# CHECK: Number: 14
+# CHECK: Name: s1234567 (73 31 32 33 34 35 36 37)
+# CHECK: }
+
+## Base 10 encoding with a small offset, section name at the beginning of the
+## string table.
+
+## /4
+##
+# CHECK: Section {
+# CHECK: Number: 15
+# CHECK: Name: s1234567z (2F 34 00 00 00 00 00 00)
+# CHECK: }
+
+## Base 10 encoding with a 7 digit offset, section name after the y padding in
+## the string table.
+
+## /1000029 == 4 + 10 + (5 * (2 + (20 * 10 * 1000) + 1))
+## v | | v ~~~~~~~~~~~~~~ v
+## table size v v "p0" y pad NULL separator
+## "s1234567z\0" # of pad sections
+##
+# CHECK: Section {
+# CHECK: Number: 16
+# CHECK: Name: sevendigitx (2F 31 30 30 30 30 32 39)
+# CHECK: }
+
+## Base 64 encoding, section name after the w padding in the string table.
+
+## //AAmJa4 == 1000029 + 12 + (5 * (2 + (9 * 20 * 10 * 1000) + 1)) == 38*64^3 + 9*64^2 + 26*64 + 56
+## v | | v ~~~~~~~~~~~~~~~~~~ v
+## sevendigitx offset v v "p0" w pad NULL separator
+## "sevendigitx\0" # of pad sections
+##
+## "2F 2F 41 41 6D 4A 61 34" is "//AAmJa4", which decodes to "0 0 38 9 26 56".
+##
+# CHECK: Section {
+# CHECK: Number: 17
+# CHECK: Name: doubleslashv (2F 2F 41 41 6D 4A 61 34)
+# CHECK: }
+
+## Generate padding sections to increase the string table size to at least
+## 1,000,000 bytes.
+.macro pad_sections2 pad
+ ## 10x \pad
+ .section p0\pad\pad\pad\pad\pad\pad\pad\pad\pad\pad; .long 1
+ .section p1\pad\pad\pad\pad\pad\pad\pad\pad\pad\pad; .long 1
+ .section p2\pad\pad\pad\pad\pad\pad\pad\pad\pad\pad; .long 1
+ .section p3\pad\pad\pad\pad\pad\pad\pad\pad\pad\pad; .long 1
+ .section p4\pad\pad\pad\pad\pad\pad\pad\pad\pad\pad; .long 1
+.endm
+
+.macro pad_sections pad
+ ## 20x \pad
+ pad_sections2 \pad\pad\pad\pad\pad\pad\pad\pad\pad\pad\pad\pad\pad\pad\pad\pad\pad\pad\pad\pad
+.endm
+
+## 1000x 'y'
+pad_sections yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy
+
+## Generate padding sections to increase the string table size to at least
+## 10,000,000 bytes.
+.macro pad_sections_ex pad
+ ## 9x \pad
+ pad_sections \pad\pad\pad\pad\pad\pad\pad\pad\pad
+.endm
+
+## 1000x 'w'
+pad_sections_ex wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww
diff --git a/llvm/tools/llvm-objcopy/CMakeLists.txt b/llvm/tools/llvm-objcopy/CMakeLists.txt
index d14d2135f5db..94d897d75944 100644
--- a/llvm/tools/llvm-objcopy/CMakeLists.txt
+++ b/llvm/tools/llvm-objcopy/CMakeLists.txt
@@ -3,6 +3,7 @@ set(LLVM_LINK_COMPONENTS
Option
Support
MC
+ BinaryFormat
)
set(LLVM_TARGET_DEFINITIONS ObjcopyOpts.td)
diff --git a/llvm/tools/llvm-objcopy/COFF/Writer.cpp b/llvm/tools/llvm-objcopy/COFF/Writer.cpp
index cbd0e4261238..fcbfef96d860 100644
--- a/llvm/tools/llvm-objcopy/COFF/Writer.cpp
+++ b/llvm/tools/llvm-objcopy/COFF/Writer.cpp
@@ -116,7 +116,7 @@ void COFFWriter::layoutSections() {
}
}
-size_t COFFWriter::finalizeStringTable() {
+Expected<size_t> COFFWriter::finalizeStringTable() {
for (const auto &S : Obj.getSections())
if (S.Name.size() > COFF::NameSize)
StrTabBuilder.add(S.Name);
@@ -129,11 +129,16 @@ size_t COFFWriter::finalizeStringTable() {
for (auto &S : Obj.getMutableSections()) {
memset(S.Header.Name, 0, sizeof(S.Header.Name));
- if (S.Name.size() > COFF::NameSize) {
- snprintf(S.Header.Name, sizeof(S.Header.Name), "/%d",
- (int)StrTabBuilder.getOffset(S.Name));
- } else {
+ if (S.Name.size() <= COFF::NameSize) {
+ // Short names can go in the field directly.
memcpy(S.Header.Name, S.Name.data(), S.Name.size());
+ } else {
+ // Offset of the section name in the string table.
+ size_t Offset = StrTabBuilder.getOffset(S.Name);
+ if (!COFF::encodeSectionName(S.Header.Name, Offset))
+ return createStringError(object_error::invalid_section_index,
+ "COFF string table is greater than 64GB, "
+ "unable to encode section name offset");
}
}
for (auto &S : Obj.getMutableSymbols()) {
@@ -219,7 +224,11 @@ Error COFFWriter::finalize(bool IsBigObj) {
Obj.PeHeader.CheckSum = 0;
}
- size_t StrTabSize = finalizeStringTable();
+ Expected<size_t> StrTabSizeOrErr = finalizeStringTable();
+ if (!StrTabSizeOrErr)
+ return StrTabSizeOrErr.takeError();
+
+ size_t StrTabSize = *StrTabSizeOrErr;
size_t PointerToSymbolTable = FileSize;
// StrTabSize <= 4 is the size of an empty string table, only consisting
diff --git a/llvm/tools/llvm-objcopy/COFF/Writer.h b/llvm/tools/llvm-objcopy/COFF/Writer.h
index eed43b3e5814..5758aadb5439 100644
--- a/llvm/tools/llvm-objcopy/COFF/Writer.h
+++ b/llvm/tools/llvm-objcopy/COFF/Writer.h
@@ -35,7 +35,7 @@ class COFFWriter {
Error finalizeRelocTargets();
Error finalizeSymbolContents();
void layoutSections();
- size_t finalizeStringTable();
+ Expected<size_t> finalizeStringTable();
Error finalize(bool IsBigObj);
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