[PATCH] D49456: [AArch64] Support execute-only LOAD segments.
Ivan Lozano via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Fri Jul 27 11:27:36 PDT 2018
ivanlozano updated this revision to Diff 157720.
ivanlozano marked 6 inline comments as done.
ivanlozano added a comment.
Added a check in finalizeSections() for intermingled data and executable sections. Also moved the computeFlags() check for ExecuteOnly to occur before the SingleRoRx check.
https://reviews.llvm.org/D49456
Files:
ELF/Config.h
ELF/Driver.cpp
ELF/Options.td
ELF/Writer.cpp
test/ELF/execute-only.s
Index: test/ELF/execute-only.s
===================================================================
--- /dev/null
+++ test/ELF/execute-only.s
@@ -0,0 +1,10 @@
+// REQUIRES: aarch64
+
+// RUN: llvm-mc -filetype=obj -triple=aarch64-linux-none %s -o %t.o
+// RUN: ld.lld -Ttext=0xcafe0000 %t.o -o %t.so -shared -execute-only
+// RUN: llvm-readelf -l %t.so | FileCheck %s
+
+// CHECK: LOAD {{.*}} 0x00000000cafe0000 0x000004 0x000004 E 0x{{.*}}
+// CHECK-NOT: LOAD {{.*}} 0x00000000cafe0000 0x000004 0x000004 R E 0x{{.*}}
+
+ br lr
Index: ELF/Writer.cpp
===================================================================
--- ELF/Writer.cpp
+++ ELF/Writer.cpp
@@ -1608,6 +1608,15 @@
if (auto *Sec = dyn_cast<OutputSection>(Base))
OutputSections.push_back(Sec);
+ // Ensure data sections are not mixed with executable sections when
+ // -execute-only is used.
+ if (Config->ExecuteOnly)
+ for (OutputSection *OS : OutputSections)
+ if (OS->Flags & SHF_EXECINSTR)
+ for (InputSection *IS : getInputSections(OS))
+ if (!(IS->Flags & SHF_EXECINSTR))
+ error("-execute-only does not support intermingling data and code");
+
// Prefer command line supplied address over other constraints.
for (OutputSection *Sec : OutputSections) {
auto I = Config->SectionStartMap.find(Sec->Name);
@@ -1766,6 +1775,8 @@
static uint64_t computeFlags(uint64_t Flags) {
if (Config->Omagic)
return PF_R | PF_W | PF_X;
+ if (Config->ExecuteOnly && (Flags & PF_X))
+ return Flags & ~PF_R;
if (Config->SingleRoRx && !(Flags & PF_W))
return Flags | PF_X;
return Flags;
Index: ELF/Options.td
===================================================================
--- ELF/Options.td
+++ ELF/Options.td
@@ -131,6 +131,10 @@
defm exclude_libs: Eq<"exclude-libs", "Exclude static libraries from automatic export">;
+defm execute_only: B<"execute-only",
+ "Do not mark executable sections readable",
+ "Mark executable sections readable (default)">;
+
defm export_dynamic: B<"export-dynamic",
"Put symbols in the dynamic symbol table",
"Do not put symbols in the dynamic symbol table (default)">;
Index: ELF/Driver.cpp
===================================================================
--- ELF/Driver.cpp
+++ ELF/Driver.cpp
@@ -299,6 +299,14 @@
if (Config->Pie)
error("-r and -pie may not be used together");
}
+
+ if (Config->ExecuteOnly) {
+ if (Config->EMachine != EM_AARCH64)
+ error("-execute-only is only supported on AArch64 targets");
+
+ if (Config->SingleRoRx)
+ error("-execute-only and -no-rosegment cannot be used together");
+ }
}
static const char *getReproduceOption(opt::InputArgList &Args) {
@@ -735,6 +743,8 @@
Config->EnableNewDtags =
Args.hasFlag(OPT_enable_new_dtags, OPT_disable_new_dtags, true);
Config->Entry = Args.getLastArgValue(OPT_entry);
+ Config->ExecuteOnly =
+ Args.hasFlag(OPT_execute_only, OPT_no_execute_only, false);
Config->ExportDynamic =
Args.hasFlag(OPT_export_dynamic, OPT_no_export_dynamic, false);
Config->FilterList = args::getStrings(Args, OPT_filter);
Index: ELF/Config.h
===================================================================
--- ELF/Config.h
+++ ELF/Config.h
@@ -130,6 +130,7 @@
bool EhFrameHdr;
bool EmitRelocs;
bool EnableNewDtags;
+ bool ExecuteOnly;
bool ExportDynamic;
bool FixCortexA53Errata843419;
bool GcSections;
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