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release/18.x: [llvm-readobj,ELF] Support --decompress/-z (#82594) #82718

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merged 1 commit into from
Feb 23, 2024

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@llvmbot llvmbot commented Feb 23, 2024

Backport 26d71d9

Requested by: @brad0

@llvmbot llvmbot added this to the LLVM 18.X Release milestone Feb 23, 2024
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llvmbot commented Feb 23, 2024

@emaste What do you think about merging this PR to the release branch?

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llvmbot commented Feb 23, 2024

@llvm/pr-subscribers-llvm-binary-utilities

Author: None (llvmbot)

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Backport 26d71d9

Requested by: @brad0


Full diff: https://github.com/llvm/llvm-project/pull/82718.diff

10 Files Affected:

  • (modified) llvm/docs/CommandGuide/llvm-readelf.rst (+5)
  • (modified) llvm/docs/CommandGuide/llvm-readobj.rst (+5)
  • (added) llvm/test/tools/llvm-readobj/ELF/decompress-zlib-unsupported.test (+32)
  • (added) llvm/test/tools/llvm-readobj/ELF/decompress-zlib.test (+76)
  • (added) llvm/test/tools/llvm-readobj/ELF/decompress-zstd-unsupported.test (+31)
  • (added) llvm/test/tools/llvm-readobj/ELF/decompress-zstd.test (+28)
  • (modified) llvm/tools/llvm-readobj/ObjDumper.cpp (+24-2)
  • (modified) llvm/tools/llvm-readobj/ObjDumper.h (+2-2)
  • (modified) llvm/tools/llvm-readobj/Opts.td (+2)
  • (modified) llvm/tools/llvm-readobj/llvm-readobj.cpp (+4-2)
diff --git a/llvm/docs/CommandGuide/llvm-readelf.rst b/llvm/docs/CommandGuide/llvm-readelf.rst
index 6ee4a5dfb15917..675628fdda45ec 100644
--- a/llvm/docs/CommandGuide/llvm-readelf.rst
+++ b/llvm/docs/CommandGuide/llvm-readelf.rst
@@ -38,6 +38,11 @@ OPTIONS
  Display the contents of the basic block address map section(s), which contain the
  address of each function, along with the relative offset of each basic block.
 
+.. option:: --decompress, -z
+
+  Dump decompressed section content when used with ``-x`` or ``-p``.
+  If the section(s) are not compressed, they are displayed as is.
+
 .. option:: --demangle, -C
 
  Display demangled symbol names in the output.
diff --git a/llvm/docs/CommandGuide/llvm-readobj.rst b/llvm/docs/CommandGuide/llvm-readobj.rst
index cb9232ef5e560a..6d78a038723445 100644
--- a/llvm/docs/CommandGuide/llvm-readobj.rst
+++ b/llvm/docs/CommandGuide/llvm-readobj.rst
@@ -56,6 +56,11 @@ file formats.
 
  Display the address-significance table.
 
+.. option:: --decompress, -z
+
+  Dump decompressed section content when used with ``-x`` or ``-p``.
+  If the section(s) are not compressed, they are displayed as is.
+
 .. option:: --expand-relocs
 
  When used with :option:`--relocs`, display each relocation in an expanded
diff --git a/llvm/test/tools/llvm-readobj/ELF/decompress-zlib-unsupported.test b/llvm/test/tools/llvm-readobj/ELF/decompress-zlib-unsupported.test
new file mode 100644
index 00000000000000..f4c73de7ca6c9d
--- /dev/null
+++ b/llvm/test/tools/llvm-readobj/ELF/decompress-zlib-unsupported.test
@@ -0,0 +1,32 @@
+# UNSUPPORTED: zlib
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-readobj -z -p .a -x .b %t 2>&1 | FileCheck %s -DFILE=%t
+
+# CHECK:      String dump of section '.a':
+# CHECK-NEXT: warning: '[[FILE]]': LLVM was not built with LLVM_ENABLE_ZLIB or did not find zlib at build time
+# CHECK-NEXT: [     0] .
+# CHECK-NEXT: [     8] .
+# CHECK-NEXT: [    10] .
+# CHECK-NEXT: [    18] x.c.
+# CHECK-NEXT: [    1e] .
+# CHECK-NEXT: [    20] .
+# CHECK-NEXT: Hex dump of section '.b':
+# CHECK-NEXT: warning: '[[FILE]]': LLVM was not built with LLVM_ENABLE_ZLIB or did not find zlib at build time
+# CHECK-NEXT: 0x00000000 01000000 00000000 01000000 00000000 ................
+# CHECK-NEXT: 0x00000010 01000000 00000000 789c6304 00000200 ........x.c.....
+# CHECK-NEXT: 0x00000020 02                                  .
+
+--- !ELF
+FileHeader:
+  Class: ELFCLASS64
+  Data:  ELFDATA2LSB
+  Type:  ET_REL
+Sections:
+  - Name: .a
+    Type: SHT_PROGBITS
+    Flags: [SHF_COMPRESSED]
+    Content: 010000000000000001000000000000000100000000000000789c63040000020002
+  - Name: .b
+    Type: SHT_PROGBITS
+    Flags: [SHF_COMPRESSED]
+    Content: 010000000000000001000000000000000100000000000000789c63040000020002
diff --git a/llvm/test/tools/llvm-readobj/ELF/decompress-zlib.test b/llvm/test/tools/llvm-readobj/ELF/decompress-zlib.test
new file mode 100644
index 00000000000000..ea7a8854eb1a0c
--- /dev/null
+++ b/llvm/test/tools/llvm-readobj/ELF/decompress-zlib.test
@@ -0,0 +1,76 @@
+# REQUIRES: zlib
+## Test --decompress/-z.
+
+# RUN: yaml2obj %s -o %t
+
+# RUN: llvm-readelf -z -x .strings -x .not_null_terminated %t | FileCheck %s --check-prefix=HEX
+# RUN: llvm-readobj --decompress -p .strings -p .not_null_terminated %t | FileCheck %s --check-prefix=STR
+
+# HEX:      Hex dump of section '.strings':
+# HEX-NEXT: 0x00000000 68657265 00617265 00736f6d 65007374 here.are.some.st
+# HEX-NEXT: 0x00000010 72696e67 7300                       rings.
+# HEX:      Hex dump of section '.not_null_terminated':
+# HEX-NEXT: 0x00000000 6e6f006e 756c6c                     no.null
+
+# STR:      String dump of section '.strings':
+# STR-NEXT: [ 0] here
+# STR-NEXT: [ 5] are
+# STR-NEXT: [ 9] some
+# STR-NEXT: [ e] strings
+# STR-EMPTY:
+# STR-NEXT: String dump of section '.not_null_terminated':
+# STR-NEXT: [ 0] no
+# STR-NEXT: [ 3] null{{$}}
+# STR-NOT:  {{.}}
+
+# RUN: llvm-readobj -x .strings -p .not_null_terminated %t | FileCheck %s --check-prefix=COMPRESSED
+
+# COMPRESSED:      String dump of section '.not_null_terminated':
+# COMPRESSED-NEXT: [     0] no
+# COMPRESSED-NEXT: [     3] null
+# COMPRESSED-NEXT: Hex dump of section '.strings':
+# COMPRESSED-NEXT: 0x00000000 01000000 00000000 16000000 00000000 ................
+# COMPRESSED-NEXT: 0x00000010 00000000 00000000 789ccb48 2d4a6548 ........x..H-JeH
+# COMPRESSED-NEXT: 0x00000020 04e2e2fc 5c205152 9499975e cc000058 ....\ QR...^...X
+# COMPRESSED-NEXT: 0x00000030 2e079b                              ...
+
+# RUN: llvm-readelf -z -p .invalid1 -x .invalid2 -x .invalid3 %t 2>&1 | FileCheck %s -DFILE=%t --check-prefix=INVALID
+
+# INVALID:      String dump of section '.invalid1':
+# INVALID-NEXT: warning: '[[FILE]]': corrupted compressed section header
+# INVALID-NEXT: [     0] .
+# INVALID-NEXT: Hex dump of section '.invalid2':
+# INVALID-NEXT: warning: '[[FILE]]': zlib error: Z_DATA_ERROR
+# INVALID-NEXT: 0x00000000 01000000 00000000 16000000 00000000 ................
+# INVALID-NEXT: 0x00000010 00000000 00000000 78                ........x
+# INVALID-EMPTY:
+# INVALID-NEXT: Hex dump of section '.invalid3':
+# INVALID-NEXT: warning: '[[FILE]]': unsupported compression type (3)
+# INVALID-NEXT: 0x00000000 03000000 00000000 04000000 00000000 ................
+# INVALID-NEXT: 0x00000010 00000000 00000000 789c6360          ........x.c`
+
+--- !ELF
+FileHeader:
+  Class: ELFCLASS64
+  Data:  ELFDATA2LSB
+  Type:  ET_REL
+Sections:
+  - Name: .strings
+    Type: SHT_PROGBITS
+    Flags: [SHF_COMPRESSED]
+    Content: 010000000000000016000000000000000000000000000000789ccb482d4a654804e2e2fc5c2051529499975ecc0000582e079b
+  - Name: .not_null_terminated
+    Type: SHT_PROGBITS
+    Content: 6e6f006e756c6c
+  - Name: .invalid1
+    Type: SHT_PROGBITS
+    Flags: [SHF_COMPRESSED]
+    Content: 01
+  - Name: .invalid2
+    Type: SHT_PROGBITS
+    Flags: [SHF_COMPRESSED]
+    Content: 01000000000000001600000000000000000000000000000078
+  - Name: .invalid3
+    Type: SHT_PROGBITS
+    Flags: [SHF_COMPRESSED]
+    Content: 030000000000000004000000000000000000000000000000789c6360
diff --git a/llvm/test/tools/llvm-readobj/ELF/decompress-zstd-unsupported.test b/llvm/test/tools/llvm-readobj/ELF/decompress-zstd-unsupported.test
new file mode 100644
index 00000000000000..65da952687f526
--- /dev/null
+++ b/llvm/test/tools/llvm-readobj/ELF/decompress-zstd-unsupported.test
@@ -0,0 +1,31 @@
+# UNSUPPORTED: zstd
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-readobj -z -p .a -x .b %t 2>&1 | FileCheck %s -DFILE=%t
+
+# CHECK:      String dump of section '.a':
+# CHECK-NEXT: warning: '[[FILE]]': LLVM was not built with LLVM_ENABLE_ZSTD or did not find zstd at build time
+# CHECK-NEXT: [     0] .
+# CHECK-NEXT: [     8] .
+# CHECK-NEXT: [    10] .
+# CHECK-NEXT: [    18] (./. ..
+# CHECK-NEXT: [    21] .
+# CHECK-NEXT: Hex dump of section '.b':
+# CHECK-NEXT: warning: '[[FILE]]': LLVM was not built with LLVM_ENABLE_ZSTD or did not find zstd at build time
+# CHECK-NEXT: 0x00000000 02000000 00000000 01000000 00000000 ................
+# CHECK-NEXT: 0x00000010 01000000 00000000 28b52ffd 20010900 ........(./. ...
+# CHECK-NEXT: 0x00000020 0001                                ..
+
+--- !ELF
+FileHeader:
+  Class: ELFCLASS64
+  Data:  ELFDATA2LSB
+  Type:  ET_REL
+Sections:
+  - Name: .a
+    Type: SHT_PROGBITS
+    Flags: [SHF_COMPRESSED]
+    Content: 02000000000000000100000000000000010000000000000028b52ffd200109000001
+  - Name: .b
+    Type: SHT_PROGBITS
+    Flags: [SHF_COMPRESSED]
+    Content: 02000000000000000100000000000000010000000000000028b52ffd200109000001
diff --git a/llvm/test/tools/llvm-readobj/ELF/decompress-zstd.test b/llvm/test/tools/llvm-readobj/ELF/decompress-zstd.test
new file mode 100644
index 00000000000000..519db879b18c17
--- /dev/null
+++ b/llvm/test/tools/llvm-readobj/ELF/decompress-zstd.test
@@ -0,0 +1,28 @@
+# REQUIRES: zstd
+## Test --decompress/-z for zstd.
+
+# RUN: yaml2obj %s -o %t
+
+# RUN: llvm-readelf -z -x .strings %t | FileCheck %s --check-prefix=HEX
+# RUN: llvm-readobj --decompress -p .strings %t | FileCheck %s --check-prefix=STR
+
+# HEX:      Hex dump of section '.strings':
+# HEX-NEXT: 0x00000000 68657265 00617265 00736f6d 65007374 here.are.some.st
+# HEX-NEXT: 0x00000010 72696e67 7300                       rings.
+
+# STR:      String dump of section '.strings':
+# STR-NEXT: [ 0] here
+# STR-NEXT: [ 5] are
+# STR-NEXT: [ 9] some
+# STR-NEXT: [ e] strings
+
+--- !ELF
+FileHeader:
+  Class: ELFCLASS64
+  Data:  ELFDATA2LSB
+  Type:  ET_REL
+Sections:
+  - Name: .strings
+    Type: SHT_PROGBITS
+    Flags: [SHF_COMPRESSED]
+    Content: 02000000000000001600000000000000000000000000000028b52ffd2016b10000686572650061726500736f6d6500737472696e677300
diff --git a/llvm/tools/llvm-readobj/ObjDumper.cpp b/llvm/tools/llvm-readobj/ObjDumper.cpp
index 59060ac217e32f..0d3fea71aafd42 100644
--- a/llvm/tools/llvm-readobj/ObjDumper.cpp
+++ b/llvm/tools/llvm-readobj/ObjDumper.cpp
@@ -14,6 +14,7 @@
 #include "ObjDumper.h"
 #include "llvm-readobj.h"
 #include "llvm/Object/Archive.h"
+#include "llvm/Object/Decompressor.h"
 #include "llvm/Object/ObjectFile.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/FormatVariadic.h"
@@ -142,8 +143,23 @@ getSectionRefsByNameOrIndex(const object::ObjectFile &Obj,
   return Ret;
 }
 
+static void maybeDecompress(const object::ObjectFile &Obj,
+                            StringRef SectionName, StringRef &SectionContent,
+                            SmallString<0> &Out) {
+  Expected<object::Decompressor> Decompressor = object::Decompressor::create(
+      SectionName, SectionContent, Obj.isLittleEndian(), Obj.is64Bit());
+  if (!Decompressor)
+    reportWarning(Decompressor.takeError(), Obj.getFileName());
+  else if (auto Err = Decompressor->resizeAndDecompress(Out))
+    reportWarning(std::move(Err), Obj.getFileName());
+  else
+    SectionContent = Out;
+}
+
 void ObjDumper::printSectionsAsString(const object::ObjectFile &Obj,
-                                      ArrayRef<std::string> Sections) {
+                                      ArrayRef<std::string> Sections,
+                                      bool Decompress) {
+  SmallString<0> Out;
   bool First = true;
   for (object::SectionRef Section :
        getSectionRefsByNameOrIndex(Obj, Sections)) {
@@ -156,12 +172,16 @@ void ObjDumper::printSectionsAsString(const object::ObjectFile &Obj,
 
     StringRef SectionContent =
         unwrapOrError(Obj.getFileName(), Section.getContents());
+    if (Decompress && Section.isCompressed())
+      maybeDecompress(Obj, SectionName, SectionContent, Out);
     printAsStringList(SectionContent);
   }
 }
 
 void ObjDumper::printSectionsAsHex(const object::ObjectFile &Obj,
-                                   ArrayRef<std::string> Sections) {
+                                   ArrayRef<std::string> Sections,
+                                   bool Decompress) {
+  SmallString<0> Out;
   bool First = true;
   for (object::SectionRef Section :
        getSectionRefsByNameOrIndex(Obj, Sections)) {
@@ -174,6 +194,8 @@ void ObjDumper::printSectionsAsHex(const object::ObjectFile &Obj,
 
     StringRef SectionContent =
         unwrapOrError(Obj.getFileName(), Section.getContents());
+    if (Decompress && Section.isCompressed())
+      maybeDecompress(Obj, SectionName, SectionContent, Out);
     const uint8_t *SecContent = SectionContent.bytes_begin();
     const uint8_t *SecEnd = SecContent + SectionContent.size();
 
diff --git a/llvm/tools/llvm-readobj/ObjDumper.h b/llvm/tools/llvm-readobj/ObjDumper.h
index 1d679453581bc8..3958dd3a333332 100644
--- a/llvm/tools/llvm-readobj/ObjDumper.h
+++ b/llvm/tools/llvm-readobj/ObjDumper.h
@@ -175,9 +175,9 @@ class ObjDumper {
   void printAsStringList(StringRef StringContent, size_t StringDataOffset = 0);
 
   void printSectionsAsString(const object::ObjectFile &Obj,
-                             ArrayRef<std::string> Sections);
+                             ArrayRef<std::string> Sections, bool Decompress);
   void printSectionsAsHex(const object::ObjectFile &Obj,
-                          ArrayRef<std::string> Sections);
+                          ArrayRef<std::string> Sections, bool Decompress);
 
   std::function<Error(const Twine &Msg)> WarningHandler;
   void reportUniqueWarning(Error Err) const;
diff --git a/llvm/tools/llvm-readobj/Opts.td b/llvm/tools/llvm-readobj/Opts.td
index e2d93c6ec229e9..018facc278e891 100644
--- a/llvm/tools/llvm-readobj/Opts.td
+++ b/llvm/tools/llvm-readobj/Opts.td
@@ -20,6 +20,7 @@ def all : FF<"all", "Equivalent to setting: --file-header, --program-headers, --
 def arch_specific : FF<"arch-specific", "Display architecture-specific information">;
 def bb_addr_map : FF<"bb-addr-map", "Display the BB address map section">;
 def cg_profile : FF<"cg-profile", "Display call graph profile section">;
+def decompress : FF<"decompress", "Dump decompressed section content when used with -x or -p">;
 defm demangle : BB<"demangle", "Demangle symbol names", "Do not demangle symbol names (default)">;
 def dependent_libraries : FF<"dependent-libraries", "Display the dependent libraries section">;
 def dyn_relocations : FF<"dyn-relocations", "Display the dynamic relocation entries in the file">;
@@ -139,3 +140,4 @@ def : F<"u", "Alias for --unwind">, Alias<unwind>;
 def : F<"X", "Alias for --extra-sym-info">, Alias<extra_sym_info>, Group<grp_elf>;
 def : F<"V", "Alias for --version-info">, Alias<version_info>, Group<grp_elf>;
 def : JoinedOrSeparate<["-"], "x">, Alias<hex_dump_EQ>, HelpText<"Alias for --hex-dump">, MetaVarName<"<name or index>">;
+def : F<"z", "Alias for --decompress">, Alias<decompress>;
diff --git a/llvm/tools/llvm-readobj/llvm-readobj.cpp b/llvm/tools/llvm-readobj/llvm-readobj.cpp
index f9d605d35244bf..979433d69011c3 100644
--- a/llvm/tools/llvm-readobj/llvm-readobj.cpp
+++ b/llvm/tools/llvm-readobj/llvm-readobj.cpp
@@ -97,6 +97,7 @@ static bool ArchSpecificInfo;
 static bool BBAddrMap;
 bool ExpandRelocs;
 static bool CGProfile;
+static bool Decompress;
 bool Demangle;
 static bool DependentLibraries;
 static bool DynRelocs;
@@ -212,6 +213,7 @@ static void parseOptions(const opt::InputArgList &Args) {
   opts::ArchSpecificInfo = Args.hasArg(OPT_arch_specific);
   opts::BBAddrMap = Args.hasArg(OPT_bb_addr_map);
   opts::CGProfile = Args.hasArg(OPT_cg_profile);
+  opts::Decompress = Args.hasArg(OPT_decompress);
   opts::Demangle = Args.hasFlag(OPT_demangle, OPT_no_demangle, false);
   opts::DependentLibraries = Args.hasArg(OPT_dependent_libraries);
   opts::DynRelocs = Args.hasArg(OPT_dyn_relocations);
@@ -439,9 +441,9 @@ static void dumpObject(ObjectFile &Obj, ScopedPrinter &Writer,
     Dumper->printSymbols(opts::Symbols, opts::DynamicSymbols,
                          opts::ExtraSymInfo, SymComp);
   if (!opts::StringDump.empty())
-    Dumper->printSectionsAsString(Obj, opts::StringDump);
+    Dumper->printSectionsAsString(Obj, opts::StringDump, opts::Decompress);
   if (!opts::HexDump.empty())
-    Dumper->printSectionsAsHex(Obj, opts::HexDump);
+    Dumper->printSectionsAsHex(Obj, opts::HexDump, opts::Decompress);
   if (opts::HashTable)
     Dumper->printHashTable();
   if (opts::GnuHashTable)

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LGTM since this helps at least FreeBSD. Does OpenBSD want to try llvm binary utilities?

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brad0 commented Feb 23, 2024

LGTM since this helps at least FreeBSD. Does OpenBSD want to try llvm binary utilities?

We're slowly moving in that direction with sparing use of llvm-objcopy, llvm-objdump and llvm-readelf in some places with a desire for more as we have with ar, ranlib and strip being updated in base.

When a section has the SHF_COMPRESSED flag, -p/-x dump the compressed
content by default. In GNU readelf, if --decompress/-z is specified,
-p/-x will dump the decompressed content. This patch implements the
option.

Close llvm#82507

(cherry picked from commit 26d71d9)
@tstellar tstellar merged commit 4ba68ab into llvm:release/18.x Feb 23, 2024
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4 participants