[lld] [lld][MachO] Support for -interposable (PR #131813)
John Holdsworth via llvm-commits
llvm-commits at lists.llvm.org
Fri Mar 21 09:02:48 PDT 2025
https://github.com/johnno1962 updated https://github.com/llvm/llvm-project/pull/131813
>From 4235b44c0ba46a237d48839ffa1b216e2a3b18bb Mon Sep 17 00:00:00 2001
From: John Holdsworth <github at johnholdsworth.com>
Date: Tue, 18 Mar 2025 17:31:40 +0100
Subject: [PATCH 1/5] [lld][MachO] Support for -interposable
---
lld/MachO/Config.h | 1 +
lld/MachO/Driver.cpp | 1 +
lld/MachO/Options.td | 7 +++----
lld/MachO/SymbolTable.cpp | 6 +++---
4 files changed, 8 insertions(+), 7 deletions(-)
diff --git a/lld/MachO/Config.h b/lld/MachO/Config.h
index f8dcc84e4ee1b..629fa2bfd0cb3 100644
--- a/lld/MachO/Config.h
+++ b/lld/MachO/Config.h
@@ -183,6 +183,7 @@ struct Configuration {
bool deadStripDylibs = false;
bool demangle = false;
bool deadStrip = false;
+ bool interposable = false;
bool errorForArchMismatch = false;
bool ignoreAutoLink = false;
// ld64 allows invalid auto link options as long as the link succeeds. LLD
diff --git a/lld/MachO/Driver.cpp b/lld/MachO/Driver.cpp
index 4f6c9b4ddc798..a335b5750b3de 100644
--- a/lld/MachO/Driver.cpp
+++ b/lld/MachO/Driver.cpp
@@ -1676,6 +1676,7 @@ bool link(ArrayRef<const char *> argsArr, llvm::raw_ostream &stdoutOS,
// Must be set before any InputSections and Symbols are created.
config->deadStrip = args.hasArg(OPT_dead_strip);
+ config->interposable = args.hasArg(OPT_interposable);
config->systemLibraryRoots = getSystemLibraryRoots(args);
if (const char *path = getReproduceOption(args)) {
diff --git a/lld/MachO/Options.td b/lld/MachO/Options.td
index 9001e85582c12..43d4266bdca06 100644
--- a/lld/MachO/Options.td
+++ b/lld/MachO/Options.td
@@ -390,6 +390,9 @@ def grp_opts : OptionGroup<"opts">, HelpText<"OPTIMIZATIONS">;
def dead_strip : Flag<["-"], "dead_strip">,
HelpText<"Remove unreachable functions and data">,
Group<grp_opts>;
+def interposable : Flag<["-"], "interposable">,
+ HelpText<"Indirects access to all to exported symbols in a dylib">,
+ Group<grp_rare>;
def order_file : Separate<["-"], "order_file">,
MetaVarName<"<file>">,
HelpText<"Layout functions and data according to specification in <file>">,
@@ -873,10 +876,6 @@ def setuid_safe : Flag<["-"], "setuid_safe">,
HelpText<"Set the MH_SETUID_SAFE bit in the mach-o header">,
Flags<[HelpHidden]>,
Group<grp_rare>;
-def interposable : Flag<["-"], "interposable">,
- HelpText<"Indirects access to all to exported symbols in a dylib">,
- Flags<[HelpHidden]>,
- Group<grp_rare>;
def multi_module : Flag<["-"], "multi_module">,
Alias<interposable>,
HelpText<"Alias for -interposable">,
diff --git a/lld/MachO/SymbolTable.cpp b/lld/MachO/SymbolTable.cpp
index a61e60a944fb4..ad48e909903b5 100644
--- a/lld/MachO/SymbolTable.cpp
+++ b/lld/MachO/SymbolTable.cpp
@@ -203,9 +203,9 @@ Defined *SymbolTable::addDefined(StringRef name, InputFile *file,
}
// With -flat_namespace, all extern symbols in dylibs are interposable.
- // FIXME: Add support for `-interposable` (PR53680).
- bool interposable = config->namespaceKind == NamespaceKind::flat &&
- config->outputType != MachO::MH_EXECUTE &&
+ bool interposable = ((config->namespaceKind == NamespaceKind::flat &&
+ config->outputType != MachO::MH_EXECUTE) ||
+ config->interposable) &&
!isPrivateExtern;
Defined *defined = replaceSymbol<Defined>(
s, name, file, isec, value, size, isWeakDef, /*isExternal=*/true,
>From 838c1546845078e9b71cdfe005b6e07c50b233eb Mon Sep 17 00:00:00 2001
From: John Holdsworth <github at johnholdsworth.com>
Date: Tue, 18 Mar 2025 19:41:21 +0100
Subject: [PATCH 2/5] Test for lld -interposable option.
---
lld/MachO/Options.td | 2 +-
lld/test/MachO/interposable.s | 34 ++++++++++++++++++++++++++++++++++
2 files changed, 35 insertions(+), 1 deletion(-)
create mode 100644 lld/test/MachO/interposable.s
diff --git a/lld/MachO/Options.td b/lld/MachO/Options.td
index 43d4266bdca06..9b35e02d8baba 100644
--- a/lld/MachO/Options.td
+++ b/lld/MachO/Options.td
@@ -392,7 +392,7 @@ def dead_strip : Flag<["-"], "dead_strip">,
Group<grp_opts>;
def interposable : Flag<["-"], "interposable">,
HelpText<"Indirects access to all to exported symbols in a dylib">,
- Group<grp_rare>;
+ Group<grp_opts>;
def order_file : Separate<["-"], "order_file">,
MetaVarName<"<file>">,
HelpText<"Layout functions and data according to specification in <file>">,
diff --git a/lld/test/MachO/interposable.s b/lld/test/MachO/interposable.s
new file mode 100644
index 0000000000000..344af2fe0bb14
--- /dev/null
+++ b/lld/test/MachO/interposable.s
@@ -0,0 +1,34 @@
+
+# RUN: rm -rf %t; split-file %s %t
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/2.s -o %t/2.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/3.s -o %t/3.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/main.s -o %t/main.o
+
+# RUN: %lld -interposable -lSystem -o %t/main %t/main.o %t/2.o %t/3.o
+# RUN: llvm-objdump --macho --lazy-bind %t/main | FileCheck %s --check-prefix BUNDLE-OBJ
+# BUNDLE-OBJ: segment section address dylib symbol
+# BUNDLE-OBJ: __DATA __la_symbol_ptr 0x{{[0-9a-f]*}} flat-namespace _main
+# BUNDLE-OBJ: __DATA __la_symbol_ptr 0x{{[0-9a-f]*}} flat-namespace my_func
+
+#--- 2.s
+# my_lib: This contains the exported function
+.globl my_func
+my_func:
+ retq
+
+#--- 3.s
+# my_user.s: This is the user/caller of the
+# exported function
+.text
+my_user:
+ callq my_func()
+ retq
+
+#--- main.s
+# main.s: dummy exec/main loads the exported function.
+# This is basically a way to say `my_user` should get
+# `my_func` from this executable.
+.globl _main
+.text
+ _main:
+ retq
>From 72e7e23ebfc4a3bdf1f588d0bcccd52f96a1f736 Mon Sep 17 00:00:00 2001
From: John Holdsworth <github at johnholdsworth.com>
Date: Wed, 19 Mar 2025 17:33:12 +0100
Subject: [PATCH 3/5] No longer .dylib only.
---
lld/MachO/Options.td | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lld/MachO/Options.td b/lld/MachO/Options.td
index 9b35e02d8baba..095de7e93660a 100644
--- a/lld/MachO/Options.td
+++ b/lld/MachO/Options.td
@@ -391,7 +391,7 @@ def dead_strip : Flag<["-"], "dead_strip">,
HelpText<"Remove unreachable functions and data">,
Group<grp_opts>;
def interposable : Flag<["-"], "interposable">,
- HelpText<"Indirects access to all to exported symbols in a dylib">,
+ HelpText<"Indirects access to all exported symbols in an image">,
Group<grp_opts>;
def order_file : Separate<["-"], "order_file">,
MetaVarName<"<file>">,
>From 8652346160e248d21d15714d3e8f00018f20c8ca Mon Sep 17 00:00:00 2001
From: John Holdsworth <github at johnholdsworth.com>
Date: Wed, 19 Mar 2025 18:12:02 +0100
Subject: [PATCH 4/5] Tweak test.
---
lld/test/MachO/interposable.s | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/lld/test/MachO/interposable.s b/lld/test/MachO/interposable.s
index 344af2fe0bb14..99e778522e0fe 100644
--- a/lld/test/MachO/interposable.s
+++ b/lld/test/MachO/interposable.s
@@ -7,8 +7,9 @@
# RUN: %lld -interposable -lSystem -o %t/main %t/main.o %t/2.o %t/3.o
# RUN: llvm-objdump --macho --lazy-bind %t/main | FileCheck %s --check-prefix BUNDLE-OBJ
# BUNDLE-OBJ: segment section address dylib symbol
-# BUNDLE-OBJ: __DATA __la_symbol_ptr 0x{{[0-9a-f]*}} flat-namespace _main
-# BUNDLE-OBJ: __DATA __la_symbol_ptr 0x{{[0-9a-f]*}} flat-namespace my_func
+# BUNDLE-OBJ-NEXT: __DATA __la_symbol_ptr 0x[[#%x,]] flat-namespace _main
+# BUNDLE-OBJ: __DATA __la_symbol_ptr 0x[[#%x,]] flat-namespace my_func
+# BUNDLE-OBJ-EMPTY:
#--- 2.s
# my_lib: This contains the exported function
>From e6b529e3d9e0caf411836748982a6d77ca0402a1 Mon Sep 17 00:00:00 2001
From: John Holdsworth <github at johnholdsworth.com>
Date: Fri, 21 Mar 2025 17:02:31 +0100
Subject: [PATCH 5/5] Check non-interposed.
---
lld/test/MachO/interposable.s | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/lld/test/MachO/interposable.s b/lld/test/MachO/interposable.s
index 99e778522e0fe..17d199322429b 100644
--- a/lld/test/MachO/interposable.s
+++ b/lld/test/MachO/interposable.s
@@ -4,12 +4,17 @@
# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/3.s -o %t/3.o
# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/main.s -o %t/main.o
+# RUN: %lld -lSystem -o %t/main %t/main.o %t/2.o %t/3.o
+# RUN: llvm-objdump --macho --lazy-bind %t/main | FileCheck %s --check-prefix BASE-OBJ
+# BASE-OBJ: segment section address dylib symbol
+# BASE-OBJ-EMPTY:
+
# RUN: %lld -interposable -lSystem -o %t/main %t/main.o %t/2.o %t/3.o
-# RUN: llvm-objdump --macho --lazy-bind %t/main | FileCheck %s --check-prefix BUNDLE-OBJ
-# BUNDLE-OBJ: segment section address dylib symbol
-# BUNDLE-OBJ-NEXT: __DATA __la_symbol_ptr 0x[[#%x,]] flat-namespace _main
-# BUNDLE-OBJ: __DATA __la_symbol_ptr 0x[[#%x,]] flat-namespace my_func
-# BUNDLE-OBJ-EMPTY:
+# RUN: llvm-objdump --macho --lazy-bind %t/main | FileCheck %s --check-prefix INTER-OBJ
+# INTER-OBJ: segment section address dylib symbol
+# INTER-OBJ-NEXT: __DATA __la_symbol_ptr 0x[[#%x,]] flat-namespace _main
+# INTER-OBJ: __DATA __la_symbol_ptr 0x[[#%x,]] flat-namespace my_func
+# INTER-OBJ-EMPTY:
#--- 2.s
# my_lib: This contains the exported function
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