[lld] cfeb25c - [lld][AArch64] Add support for GCS (#90732)
via llvm-commits
llvm-commits at lists.llvm.org
Tue May 21 09:34:21 PDT 2024
Author: John Brawn
Date: 2024-05-21T17:34:17+01:00
New Revision: cfeb25cd7e92d5e854aa92034f18da2e5fa3e27a
URL: https://github.com/llvm/llvm-project/commit/cfeb25cd7e92d5e854aa92034f18da2e5fa3e27a
DIFF: https://github.com/llvm/llvm-project/commit/cfeb25cd7e92d5e854aa92034f18da2e5fa3e27a.diff
LOG: [lld][AArch64] Add support for GCS (#90732)
This adds the -z gcs and -z gcs-report options, which behave similarly
to -z shtk and -z cet-report, except that -z gcs accepts a parameter:
* -z gcs=implicit is the default behaviour, where the GCS bit is
inferred from the input objects.
* -z gcs=never clears the GCS bit, ignoring the input objects.
* -z gcs=always sets the GCS bit, ignoring the input objects.
This is so that there's a means of explicitly disabling GCS even when
all input objects have the GCS bit set.
Added:
lld/test/ELF/aarch64-feature-gcs.s
Modified:
lld/ELF/Config.h
lld/ELF/Driver.cpp
Removed:
################################################################################
diff --git a/lld/ELF/Config.h b/lld/ELF/Config.h
index dbb81412453af..f0dfe7f377de0 100644
--- a/lld/ELF/Config.h
+++ b/lld/ELF/Config.h
@@ -102,6 +102,9 @@ enum class GnuStackKind { None, Exec, NoExec };
// For --lto=
enum LtoKind : uint8_t {UnifiedThin, UnifiedRegular, Default};
+// For -z gcs=
+enum class GcsPolicy { Implicit, Never, Always };
+
struct SymbolVersion {
llvm::StringRef name;
bool isExternCpp;
@@ -188,6 +191,7 @@ struct Config {
StringRef zBtiReport = "none";
StringRef zCetReport = "none";
StringRef zPauthReport = "none";
+ StringRef zGcsReport = "none";
bool ltoBBAddrMap;
llvm::StringRef ltoBasicBlockSections;
std::pair<llvm::StringRef, llvm::StringRef> thinLTOObjectSuffixReplace;
@@ -341,6 +345,7 @@ struct Config {
UnresolvedPolicy unresolvedSymbols;
UnresolvedPolicy unresolvedSymbolsInShlib;
Target2Policy target2;
+ GcsPolicy zGcs;
bool power10Stubs;
ARMVFPArgKind armVFPArgs = ARMVFPArgKind::Default;
BuildIdKind buildId = BuildIdKind::None;
diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index 028cdcc83d2fb..ddc574a11314b 100644
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -466,6 +466,10 @@ static void checkOptions() {
error("-z bti-report only supported on AArch64");
if (config->zPauthReport != "none")
error("-z pauth-report only supported on AArch64");
+ if (config->zGcsReport != "none")
+ error("-z gcs-report only supported on AArch64");
+ if (config->zGcs != GcsPolicy::Implicit)
+ error("-z gcs only supported on AArch64");
}
if (config->emachine != EM_386 && config->emachine != EM_X86_64 &&
@@ -560,6 +564,25 @@ static uint8_t getZStartStopVisibility(opt::InputArgList &args) {
return ret;
}
+static GcsPolicy getZGcs(opt::InputArgList &args) {
+ GcsPolicy ret = GcsPolicy::Implicit;
+ for (auto *arg : args.filtered(OPT_z)) {
+ std::pair<StringRef, StringRef> kv = StringRef(arg->getValue()).split('=');
+ if (kv.first == "gcs") {
+ arg->claim();
+ if (kv.second == "implicit")
+ ret = GcsPolicy::Implicit;
+ else if (kv.second == "never")
+ ret = GcsPolicy::Never;
+ else if (kv.second == "always")
+ ret = GcsPolicy::Always;
+ else
+ error("unknown -z gcs= value: " + kv.second);
+ }
+ }
+ return ret;
+}
+
// Report a warning for an unknown -z option.
static void checkZOptions(opt::InputArgList &args) {
// This function is called before getTarget(), when certain options are not
@@ -1438,6 +1461,7 @@ static void readConfigs(opt::InputArgList &args) {
config->zCopyreloc = getZFlag(args, "copyreloc", "nocopyreloc", true);
config->zForceBti = hasZOption(args, "force-bti");
config->zForceIbt = hasZOption(args, "force-ibt");
+ config->zGcs = getZGcs(args);
config->zGlobal = hasZOption(args, "global");
config->zGnustack = getZGnuStack(args);
config->zHazardplt = hasZOption(args, "hazardplt");
@@ -1510,6 +1534,7 @@ static void readConfigs(opt::InputArgList &args) {
auto reports = {std::make_pair("bti-report", &config->zBtiReport),
std::make_pair("cet-report", &config->zCetReport),
+ std::make_pair("gcs-report", &config->zGcsReport),
std::make_pair("pauth-report", &config->zPauthReport)};
for (opt::Arg *arg : args.filtered(OPT_z)) {
std::pair<StringRef, StringRef> option =
@@ -2677,6 +2702,11 @@ static void readSecurityNotes() {
toString(f) + ": -z bti-report: file does not have "
"GNU_PROPERTY_AARCH64_FEATURE_1_BTI property");
+ checkAndReportMissingFeature(
+ config->zGcsReport, features, GNU_PROPERTY_AARCH64_FEATURE_1_GCS,
+ toString(f) + ": -z gcs-report: file does not have "
+ "GNU_PROPERTY_AARCH64_FEATURE_1_GCS property");
+
checkAndReportMissingFeature(
config->zCetReport, features, GNU_PROPERTY_X86_FEATURE_1_IBT,
toString(f) + ": -z cet-report: file does not have "
@@ -2729,6 +2759,12 @@ static void readSecurityNotes() {
// Force enable Shadow Stack.
if (config->zShstk)
config->andFeatures |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
+
+ // Force enable/disable GCS
+ if (config->zGcs == GcsPolicy::Always)
+ config->andFeatures |= GNU_PROPERTY_AARCH64_FEATURE_1_GCS;
+ else if (config->zGcs == GcsPolicy::Never)
+ config->andFeatures &= ~GNU_PROPERTY_AARCH64_FEATURE_1_GCS;
}
static void initSectionsAndLocalSyms(ELFFileBase *file, bool ignoreComdats) {
diff --git a/lld/test/ELF/aarch64-feature-gcs.s b/lld/test/ELF/aarch64-feature-gcs.s
new file mode 100644
index 0000000000000..7a08673dbb7e6
--- /dev/null
+++ b/lld/test/ELF/aarch64-feature-gcs.s
@@ -0,0 +1,134 @@
+# REQUIRES: aarch64
+# RUN: rm -rf %t && split-file %s %t && cd %t
+# RUN: llvm-mc -filetype=obj -triple=aarch64-linux-gnu func1-gcs.s -o func1-gcs.o
+# RUN: llvm-mc -filetype=obj -triple=aarch64-linux-gnu func2.s -o func2.o
+# RUN: llvm-mc -filetype=obj -triple=aarch64-linux-gnu func2-gcs.s -o func2-gcs.o
+# RUN: llvm-mc -filetype=obj -triple=aarch64-linux-gnu func3.s -o func3.o
+# RUN: llvm-mc -filetype=obj -triple=aarch64-linux-gnu func3-gcs.s -o func3-gcs.o
+
+## GCS should be enabled when it's enabled in all inputs or when it's forced on.
+
+# RUN: ld.lld func1-gcs.o func2-gcs.o func3-gcs.o -o gcs
+# RUN: llvm-readelf -n gcs | FileCheck --check-prefix GCS %s
+# RUN: ld.lld func1-gcs.o func3-gcs.o --shared -o gcs.so
+# RUN: llvm-readelf -n gcs.so | FileCheck --check-prefix GCS %s
+# RUN: ld.lld func1-gcs.o func2.o func3-gcs.o -o force-gcs -z gcs=always
+# RUN: llvm-readelf -n force-gcs | FileCheck --check-prefix GCS %s
+# RUN: ld.lld func2-gcs.o func3.o --shared -o force-gcs.so -z gcs=always
+# RUN: llvm-readelf -n force-gcs.so | FileCheck --check-prefix GCS %s
+# RUN: ld.lld func2-gcs.o func3.o --shared -o force-gcs2.so -z gcs=never -z gcs=always
+# RUN: llvm-readelf -n force-gcs2.so | FileCheck --check-prefix GCS %s
+
+# GCS: Properties: aarch64 feature: GCS
+
+## GCS should not be enabled if it's not enabled in at least one input.
+
+# RUN: ld.lld func1-gcs.o func2.o func3-gcs.o -o no-gcs
+# RUN: llvm-readelf -n no-gcs | count 0
+# RUN: ld.lld func2-gcs.o func3.o --shared -o no-gcs.so
+
+## GCS should be disabled with gcs=never, even if GCS is present in all inputs.
+
+# RUN: ld.lld func1-gcs.o func2-gcs.o func3-gcs.o -z gcs=never -o never-gcs
+# RUN: llvm-readelf -n never-gcs | count 0
+# RUN: ld.lld func1-gcs.o func2-gcs.o func3-gcs.o -z gcs=always -z gcs=never -o never-gcs2
+# RUN: llvm-readelf -n never-gcs2 | count 0
+
+## gcs-report should report any input files that don't have the gcs property.
+
+# RUN: ld.lld func1-gcs.o func2.o func3-gcs.o -o /dev/null -z gcs-report=warning 2>&1 | FileCheck --check-prefix=REPORT-WARN %s
+# RUN: ld.lld func1-gcs.o func2.o func3-gcs.o -o /dev/null -z gcs-report=warning -z gcs=always 2>&1 | FileCheck --check-prefix=REPORT-WARN %s
+# RUN: ld.lld func1-gcs.o func2.o func3-gcs.o -o /dev/null -z gcs-report=warning -z gcs=never 2>&1 | FileCheck --check-prefix=REPORT-WARN %s
+# RUN: not ld.lld func2-gcs.o func3.o --shared -o /dev/null -z gcs-report=error 2>&1 | FileCheck --check-prefix=REPORT-ERROR %s
+# RUN: not ld.lld func2-gcs.o func3.o --shared -o /dev/null -z gcs-report=error -z gcs=always 2>&1 | FileCheck --check-prefix=REPORT-ERROR %s
+# RUN: not ld.lld func2-gcs.o func3.o --shared -o /dev/null -z gcs-report=error -z gcs=never 2>&1 | FileCheck --check-prefix=REPORT-ERROR %s
+# RUN: ld.lld func1-gcs.o func2-gcs.o func3-gcs.o -o /dev/null -z gcs-report=warning 2>&1 | count 0
+# RUN: ld.lld func1-gcs.o func2-gcs.o func3-gcs.o -o /dev/null -z gcs-report=warning -z gcs=always 2>&1 | count 0
+# RUN: ld.lld func1-gcs.o func2-gcs.o func3-gcs.o -o /dev/null -z gcs-report=warning -z gcs=never 2>&1 | count 0
+
+# REPORT-WARN: warning: func2.o: -z gcs-report: file does not have GNU_PROPERTY_AARCH64_FEATURE_1_GCS property
+# REPORT-ERROR: error: func3.o: -z gcs-report: file does not have GNU_PROPERTY_AARCH64_FEATURE_1_GCS property
+
+## An invalid gcs option should give an error
+# RUN: not ld.lld func1-gcs.o func2-gcs.o func3-gcs.o -z gcs=nonsense 2>&1 | FileCheck --check-prefix=INVALID %s
+
+# INVALID: error: unknown -z gcs= value: nonsense
+
+#--- func1-gcs.s
+.section ".note.gnu.property", "a"
+.long 4
+.long 0x10
+.long 0x5
+.asciz "GNU"
+
+.long 0xc0000000 // GNU_PROPERTY_AARCH64_FEATURE_1_AND
+.long 4
+.long 4 // GNU_PROPERTY_AARCH64_FEATURE_1_GCS
+.long 0
+
+.text
+.globl _start
+.type func1,%function
+func1:
+ bl func2
+ ret
+
+#--- func2.s
+
+.text
+.globl func2
+.type func2, at function
+func2:
+ .globl func3
+ .type func3, @function
+ bl func3
+ ret
+
+#--- func2-gcs.s
+
+.section ".note.gnu.property", "a"
+.long 4
+.long 0x10
+.long 0x5
+.asciz "GNU"
+
+.long 0xc0000000 // GNU_PROPERTY_AARCH64_FEATURE_1_AND
+.long 4
+.long 4 // GNU_PROPERTY_AARCH64_FEATURE_1_GCS
+.long 0
+
+.text
+.globl func2
+.type func2, at function
+func2:
+ .globl func3
+ .type func3, @function
+ bl func3
+ ret
+
+#--- func3.s
+
+.text
+.globl func3
+.type func3, at function
+func3:
+ ret
+
+#--- func3-gcs.s
+
+.section ".note.gnu.property", "a"
+.long 4
+.long 0x10
+.long 0x5
+.asciz "GNU"
+
+.long 0xc0000000 // GNU_PROPERTY_AARCH64_FEATURE_1_AND
+.long 4
+.long 4 // GNU_PROPERTY_AARCH64_FEATURE_1_GCS
+.long 0
+
+.text
+.globl func3
+.type func3, at function
+func3:
+ ret
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