[lld-macho] Implement -segprot
Addresses llvm.org/PR49405.
Reviewed By: #lld-macho, oontvoo
Differential Revision: https://reviews.llvm.org/D99389
GitOrigin-RevId: a43f588e0128bfb5ba10f6dbe7069e55bfa5ec51
diff --git a/MachO/Config.h b/MachO/Config.h
index 810ae7b..c629c84 100644
--- a/MachO/Config.h
+++ b/MachO/Config.h
@@ -50,6 +50,12 @@
dynamic_lookup,
};
+struct SegmentProtection {
+ llvm::StringRef name;
+ uint32_t maxProt;
+ uint32_t initProt;
+};
+
class SymbolPatterns {
public:
// GlobPattern can also match literals,
@@ -104,6 +110,9 @@
std::vector<llvm::StringRef> frameworkSearchPaths;
std::vector<llvm::StringRef> runtimePaths;
std::vector<Symbol *> explicitUndefineds;
+ // There are typically very few custom segmentProtections, so use a vector
+ // instead of a map.
+ std::vector<SegmentProtection> segmentProtections;
llvm::DenseMap<llvm::StringRef, SymbolPriorityEntry> priorities;
SectionRenameMap sectionRenameMap;
diff --git a/MachO/Driver.cpp b/MachO/Driver.cpp
index d262ad5..96f8195 100644
--- a/MachO/Driver.cpp
+++ b/MachO/Driver.cpp
@@ -724,6 +724,29 @@
return version.rawValue();
}
+static uint32_t parseProtection(StringRef protStr) {
+ uint32_t prot = 0;
+ for (char c : protStr) {
+ switch (c) {
+ case 'r':
+ prot |= VM_PROT_READ;
+ break;
+ case 'w':
+ prot |= VM_PROT_WRITE;
+ break;
+ case 'x':
+ prot |= VM_PROT_EXECUTE;
+ break;
+ case '-':
+ break;
+ default:
+ error("unknown -segprot letter '" + Twine(c) + "' in " + protStr);
+ return 0;
+ }
+ }
+ return prot;
+}
+
void SymbolPatterns::clear() {
literals.clear();
globs.clear();
@@ -966,6 +989,18 @@
validName(arg->getValue(1));
}
+ for (const Arg *arg : args.filtered(OPT_segprot)) {
+ StringRef segName = arg->getValue(0);
+ uint32_t maxProt = parseProtection(arg->getValue(1));
+ uint32_t initProt = parseProtection(arg->getValue(2));
+ if (maxProt != initProt && config->target.Arch != AK_i386)
+ error("invalid argument '" + arg->getAsString(args) +
+ "': max and init must be the same for non-i386 archs");
+ if (segName == segment_names::linkEdit)
+ error("-segprot cannot be used to change __LINKEDIT's protections");
+ config->segmentProtections.push_back({segName, maxProt, initProt});
+ }
+
handleSymbolPatterns(args, config->exportedSymbols, OPT_exported_symbol,
OPT_exported_symbols_list);
handleSymbolPatterns(args, config->unexportedSymbols, OPT_unexported_symbol,
diff --git a/MachO/Options.td b/MachO/Options.td
index da2c53e..6a963ff 100644
--- a/MachO/Options.td
+++ b/MachO/Options.td
@@ -772,8 +772,7 @@
Group<grp_rare>;
def segprot : MultiArg<["-"], "segprot", 3>,
MetaVarName<"<segment> <max> <init>">,
- HelpText<"Specifies the <max> and <init> virtual memory protection of <segment> as r/w/x/-seg_addr_table path Specify hex base addresses and dylib install names on successive lines in <path>. This option is obsolete">,
- Flags<[HelpHidden]>,
+ HelpText<"Specifies the <max> and <init> virtual memory protection of <segment> as r/w/x/-seg_addr_table path">,
Group<grp_rare>;
def segs_read_write_addr : Separate<["-"], "segs_read_write_addr">,
MetaVarName<"<address>">,
diff --git a/MachO/OutputSegment.cpp b/MachO/OutputSegment.cpp
index edfc474..71da2ef 100644
--- a/MachO/OutputSegment.cpp
+++ b/MachO/OutputSegment.cpp
@@ -21,6 +21,12 @@
using namespace lld::macho;
static uint32_t initProt(StringRef name) {
+ auto it = find_if(
+ config->segmentProtections,
+ [&](const SegmentProtection &segprot) { return segprot.name == name; });
+ if (it != config->segmentProtections.end())
+ return it->initProt;
+
if (name == segment_names::text)
return VM_PROT_READ | VM_PROT_EXECUTE;
if (name == segment_names::pageZero)
diff --git a/test/MachO/segprot.s b/test/MachO/segprot.s
new file mode 100644
index 0000000..a4e91d1
--- /dev/null
+++ b/test/MachO/segprot.s
@@ -0,0 +1,48 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %s -o %t.o
+
+## Make sure the option parser doesn't think --x and -w are flags.
+# RUN: %lld -dylib -o %t %t.o -segprot FOO rwx xwr -segprot BAR --x --x -segprot BAZ -w -w
+# RUN: llvm-readobj --macho-segment %t | FileCheck %s
+
+# CHECK: Name: FOO
+# CHECK-NEXT: Size:
+# CHECK-NEXT: vmaddr:
+# CHECK-NEXT: vmsize:
+# CHECK-NEXT: fileoff:
+# CHECK-NEXT: filesize:
+# CHECK-NEXT: maxprot: rwx
+# CHECK-NEXT: initprot: rwx
+
+# CHECK: Name: BAR
+# CHECK-NEXT: Size:
+# CHECK-NEXT: vmaddr:
+# CHECK-NEXT: vmsize:
+# CHECK-NEXT: fileoff:
+# CHECK-NEXT: filesize:
+# CHECK-NEXT: maxprot: --x
+# CHECK-NEXT: initprot: --x
+
+# CHECK: Name: BAZ
+# CHECK-NEXT: Size:
+# CHECK-NEXT: vmaddr:
+# CHECK-NEXT: vmsize:
+# CHECK-NEXT: fileoff:
+# CHECK-NEXT: filesize:
+# CHECK-NEXT: maxprot: -w-
+# CHECK-NEXT: initprot: -w-
+
+# RUN: not %lld -dylib -o /dev/null %t.o -segprot FOO rwx rw 2>&1 | FileCheck %s --check-prefix=MISMATCH
+# RUN: not %lld -dylib -o /dev/null %t.o -segprot __LINKEDIT rwx rwx 2>&1 | FileCheck %s --check-prefix=NO-LINKEDIT
+# RUN: not %lld -dylib -o /dev/null %t.o -segprot FOO uhh wat 2>&1 | FileCheck %s --check-prefix=MISPARSE
+# RUN: not %lld -dylib -o /dev/null %t.o -segprot FOO rwx 2>&1 | FileCheck %s --check-prefix=MISSING
+
+# MISMATCH: error: invalid argument '-segprot FOO rwx rw': max and init must be the same for non-i386 archs
+# NO-LINKEDIT: error: -segprot cannot be used to change __LINKEDIT's protections
+# MISPARSE: error: unknown -segprot letter 'u' in uhh
+# MISPARSE: error: unknown -segprot letter 'a' in wat
+# MISSING: error: -segprot: missing argument
+
+.section FOO,foo
+.section BAR,bar
+.section BAZ,baz
