[lld] b616262 - [LLD][ELF][AArch64] Change the semantics of -z pac-plt.
Daniel Kiss via llvm-commits
llvm-commits at lists.llvm.org
Tue Feb 18 00:57:04 PST 2020
Author: Daniel Kiss
Date: 2020-02-18T09:56:57+01:00
New Revision: b6162622c054fa74a7f2588df00059475f112212
URL: https://github.com/llvm/llvm-project/commit/b6162622c054fa74a7f2588df00059475f112212
DIFF: https://github.com/llvm/llvm-project/commit/b6162622c054fa74a7f2588df00059475f112212.diff
LOG: [LLD][ELF][AArch64] Change the semantics of -z pac-plt.
Summary:
Generate PAC protected plt only when "-z pac-plt" is passed to the
linker. GNU toolchain generates when it is explicitly requested[1].
When pac-plt is requested then set the GNU_PROPERTY_AARCH64_FEATURE_1_PAC
note even when not all function compiled with PAC but issue a warning.
Harmonizing the warning style for BTI/PAC/IBT.
Generate BTI protected PLT if case of "-z force-bti".
[1] https://www.sourceware.org/ml/binutils/2019-03/msg00021.html
Reviewers: peter.smith, espindola, MaskRay, grimar
Reviewed By: peter.smith, MaskRay
Subscribers: tatyana-krasnukha, emaste, arichardson, kristof.beyls, MaskRay, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D74537
Added:
Modified:
lld/ELF/Arch/AArch64.cpp
lld/ELF/Driver.cpp
lld/ELF/SyntheticSections.cpp
lld/test/ELF/aarch64-feature-bti.s
lld/test/ELF/aarch64-feature-btipac.s
lld/test/ELF/aarch64-feature-pac.s
Removed:
################################################################################
diff --git a/lld/ELF/Arch/AArch64.cpp b/lld/ELF/Arch/AArch64.cpp
index 72317070ff96..324516314d03 100644
--- a/lld/ELF/Arch/AArch64.cpp
+++ b/lld/ELF/Arch/AArch64.cpp
@@ -601,8 +601,10 @@ AArch64BtiPac::AArch64BtiPac() {
// the function in an executable being taken by a shared library.
// FIXME: There is a potential optimization to omit the BTI if we detect
// that the address of the PLT entry isn't taken.
+ // The PAC PLT entries require dynamic loader support and this isn't known
+ // from properties in the objects, so we use the command line flag.
btiEntry = btiHeader && !config->shared;
- pacEntry = (config->andFeatures & GNU_PROPERTY_AARCH64_FEATURE_1_PAC);
+ pacEntry = config->zPacPlt;
if (btiEntry || pacEntry) {
pltEntrySize = 24;
diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index 021895aa4e97..06512e2689ae 100644
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -1736,7 +1736,8 @@ template <class ELFT> static uint32_t getAndFeatures() {
for (InputFile *f : objectFiles) {
uint32_t features = cast<ObjFile<ELFT>>(f)->andFeatures;
if (config->zForceBti && !(features & GNU_PROPERTY_AARCH64_FEATURE_1_BTI)) {
- warn(toString(f) + ": -z force-bti: file does not have BTI property");
+ warn(toString(f) + ": -z force-bti: file does not have "
+ "GNU_PROPERTY_AARCH64_FEATURE_1_BTI property");
features |= GNU_PROPERTY_AARCH64_FEATURE_1_BTI;
} else if (config->zForceIbt &&
!(features & GNU_PROPERTY_X86_FEATURE_1_IBT)) {
@@ -1744,13 +1745,14 @@ template <class ELFT> static uint32_t getAndFeatures() {
"GNU_PROPERTY_X86_FEATURE_1_IBT property");
features |= GNU_PROPERTY_X86_FEATURE_1_IBT;
}
+ if (config->zPacPlt && !(features & GNU_PROPERTY_AARCH64_FEATURE_1_PAC)) {
+ warn(toString(f) + ": -z pac-plt: file does not have "
+ "GNU_PROPERTY_AARCH64_FEATURE_1_PAC property");
+ features |= GNU_PROPERTY_AARCH64_FEATURE_1_PAC;
+ }
ret &= features;
}
- // Force enable pointer authentication Plt, we don't warn in this case as
- // this does not require support in the object for correctness.
- if (config->zPacPlt)
- ret |= GNU_PROPERTY_AARCH64_FEATURE_1_PAC;
// Force enable Shadow Stack.
if (config->zShstk)
ret |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
diff --git a/lld/ELF/SyntheticSections.cpp b/lld/ELF/SyntheticSections.cpp
index 3a0251c90692..8fede224b56d 100644
--- a/lld/ELF/SyntheticSections.cpp
+++ b/lld/ELF/SyntheticSections.cpp
@@ -1401,7 +1401,7 @@ template <class ELFT> void DynamicSection<ELFT>::finalizeContents() {
if (config->emachine == EM_AARCH64) {
if (config->andFeatures & GNU_PROPERTY_AARCH64_FEATURE_1_BTI)
addInt(DT_AARCH64_BTI_PLT, 0);
- if (config->andFeatures & GNU_PROPERTY_AARCH64_FEATURE_1_PAC)
+ if (config->zPacPlt)
addInt(DT_AARCH64_PAC_PLT, 0);
}
diff --git a/lld/test/ELF/aarch64-feature-bti.s b/lld/test/ELF/aarch64-feature-bti.s
index cbaf17b4d960..e1a7f516c135 100644
--- a/lld/test/ELF/aarch64-feature-bti.s
+++ b/lld/test/ELF/aarch64-feature-bti.s
@@ -174,7 +174,7 @@
# RUN: ld.lld %t.o %t2.o -z force-bti %t.so -o %tforcebti.exe 2>&1 | FileCheck --check-prefix=FORCE-WARN %s
-# FORCE-WARN: aarch64-feature-bti.s.tmp2.o: -z force-bti: file does not have BTI property
+# FORCE-WARN: aarch64-feature-bti.s.tmp2.o: -z force-bti: file does not have GNU_PROPERTY_AARCH64_FEATURE_1_BTI property
# RUN: llvm-readelf -n %tforcebti.exe | FileCheck --check-prefix=BTIPROP %s
diff --git a/lld/test/ELF/aarch64-feature-btipac.s b/lld/test/ELF/aarch64-feature-btipac.s
index 17f8487f4d3f..f41412cd3ccd 100644
--- a/lld/test/ELF/aarch64-feature-btipac.s
+++ b/lld/test/ELF/aarch64-feature-btipac.s
@@ -25,32 +25,30 @@
# BTIPACSO-NEXT: 10360: bti c
# BTIPACSO-NEXT: stp x16, x30, [sp, #-16]!
# BTIPACSO-NEXT: adrp x16, #131072
-# BTIPACSO-NEXT: ldr x17, [x16, #1160]
-# BTIPACSO-NEXT: add x16, x16, #1160
+# BTIPACSO-NEXT: ldr x17, [x16, #1136]
+# BTIPACSO-NEXT: add x16, x16, #1136
# BTIPACSO-NEXT: br x17
# BTIPACSO-NEXT: nop
# BTIPACSO-NEXT: nop
# BTIPACSO: 0000000000010380 func3 at plt:
# BTIPACSO-NEXT: 10380: adrp x16, #131072
-# BTIPACSO-NEXT: ldr x17, [x16, #1168]
-# BTIPACSO-NEXT: add x16, x16, #1168
-# BTIPACSO-NEXT: autia1716
+# BTIPACSO-NEXT: ldr x17, [x16, #1144]
+# BTIPACSO-NEXT: add x16, x16, #1144
# BTIPACSO-NEXT: br x17
-# BTIPACSO-NEXT: nop
# BTIPACPROP: Properties: aarch64 feature: BTI, PAC
# BTIPACDYN: 0x0000000070000001 (AARCH64_BTI_PLT)
-# BTIPACDYN: 0x0000000070000003 (AARCH64_PAC_PLT)
+# BTIPACDYN-NOT: 0x0000000070000003 (AARCH64_PAC_PLT)
## Make an executable with both BTI and PAC properties. Expect:
## PLT[0] bti c as first instruction
-## PLT[n] bti n as first instruction, autia1716 before br x17
+## PLT[n] bti n as first instruction
# RUN: ld.lld %t.o %t3btipac.o %t.so -o %t.exe
# RUN: llvm-readelf -n %t.exe | FileCheck --check-prefix=BTIPACPROP %s
# RUN: llvm-objdump -d -mattr=+v8.5a --no-show-raw-insn %t.exe | FileCheck --check-prefix BTIPACEX %s
-# RUN: llvm-readelf --dynamic-table %t.exe | FileCheck --check-prefix BTIPACDYN %s
+# RUN: llvm-readelf --dynamic-table %t.exe | FileCheck --check-prefix BTIPACDYNEX %s
# BTIPACEX: Disassembly of section .text:
# BTIPACEX: 0000000000210370 func1:
@@ -64,19 +62,21 @@
# BTIPACEX-NEXT: 210380: bti c
# BTIPACEX-NEXT: stp x16, x30, [sp, #-16]!
# BTIPACEX-NEXT: adrp x16, #131072
-# BTIPACEX-NEXT: ldr x17, [x16, #1208]
-# BTIPACEX-NEXT: add x16, x16, #1208
+# BTIPACEX-NEXT: ldr x17, [x16, #1192]
+# BTIPACEX-NEXT: add x16, x16, #1192
# BTIPACEX-NEXT: br x17
# BTIPACEX-NEXT: nop
# BTIPACEX-NEXT: nop
# BTIPACEX: 00000000002103a0 func2 at plt:
# BTIPACEX-NEXT: 2103a0: bti c
# BTIPACEX-NEXT: adrp x16, #131072
-# BTIPACEX-NEXT: ldr x17, [x16, #1216]
-# BTIPACEX-NEXT: add x16, x16, #1216
-# BTIPACEX-NEXT: autia1716
+# BTIPACEX-NEXT: ldr x17, [x16, #1200]
+# BTIPACEX-NEXT: add x16, x16, #1200
# BTIPACEX-NEXT: br x17
+# BTIPACDYNEX: 0x0000000070000001 (AARCH64_BTI_PLT)
+# BTIPACDYNEX-NOT: 0x0000000070000003 (AARCH64_PAC_PLT)
+
## Check that combinations of BTI+PAC with 0 properties results in standard PLT
# RUN: ld.lld %t.o %t3.o %t.so -o %t.exe
@@ -112,14 +112,17 @@
## Check that combination of -z pac-plt and -z force-bti warns for the file that
## doesn't contain the BTI property, but generates PAC and BTI PLT sequences.
## The -z pac-plt doesn't warn as it is not required for correctness.
+## Expect:
+## PLT[0] bti c as first instruction
+## PLT[n] bti n as first instruction, autia1716 before br x17
# RUN: ld.lld %t.o %t3.o %t.so -z pac-plt -z force-bti -o %t.exe 2>&1 | FileCheck --check-prefix=FORCE-WARN %s
-# FORCE-WARN: aarch64-feature-btipac.s.tmp3.o: -z force-bti: file does not have BTI property
+# FORCE-WARN: aarch64-feature-btipac.s.tmp3.o: -z force-bti: file does not have GNU_PROPERTY_AARCH64_FEATURE_1_BTI property
# RUN: llvm-readelf -n %t.exe | FileCheck --check-prefix=BTIPACPROP %s
-# RUN: llvm-objdump -d -mattr=+v8.5a --no-show-raw-insn %t.exe | FileCheck --check-prefix BTIPACEX %s
-# RUN: llvm-readelf --dynamic-table %t.exe | FileCheck --check-prefix BTIPACDYN %s
+# RUN: llvm-objdump -d -mattr=+v8.5a --no-show-raw-insn %t.exe | FileCheck --check-prefix BTIPACEX2 %s
+# RUN: llvm-readelf --dynamic-table %t.exe | FileCheck --check-prefix BTIPACDYN2 %s
.section ".note.gnu.property", "a"
.long 4
.long 0x10
@@ -140,3 +143,31 @@ func1:
.globl func3
.type func3,%function
ret
+
+# BTIPACEX2: Disassembly of section .text:
+# BTIPACEX2: 0000000000210370 func1:
+# BTIPACEX2-NEXT: 210370: bl #48 <func2 at plt>
+# BTIPACEX2-NEXT: ret
+# BTIPACEX2-NEXT: ret
+# BTIPACEX2: 000000000021037c func3:
+# BTIPACEX2-NEXT: 21037c: ret
+# BTIPACEX2: Disassembly of section .plt:
+# BTIPACEX2: 0000000000210380 .plt:
+# BTIPACEX2-NEXT: 210380: bti c
+# BTIPACEX2-NEXT: stp x16, x30, [sp, #-16]!
+# BTIPACEX2-NEXT: adrp x16, #131072
+# BTIPACEX2-NEXT: ldr x17, [x16, #1208]
+# BTIPACEX2-NEXT: add x16, x16, #1208
+# BTIPACEX2-NEXT: br x17
+# BTIPACEX2-NEXT: nop
+# BTIPACEX2-NEXT: nop
+# BTIPACEX2: 00000000002103a0 func2 at plt:
+# BTIPACEX2-NEXT: 2103a0: bti c
+# BTIPACEX2-NEXT: adrp x16, #131072
+# BTIPACEX2-NEXT: ldr x17, [x16, #1216]
+# BTIPACEX2-NEXT: add x16, x16, #1216
+# BTIPACEX2-NEXT: autia1716
+# BTIPACEX2-NEXT: br x17
+
+# BTIPACDYN2: 0x0000000070000001 (AARCH64_BTI_PLT)
+# BTIPACDYN2-NEXT: 0x0000000070000003 (AARCH64_PAC_PLT)
\ No newline at end of file
diff --git a/lld/test/ELF/aarch64-feature-pac.s b/lld/test/ELF/aarch64-feature-pac.s
index 41c6cb69742a..9dd6129396f6 100644
--- a/lld/test/ELF/aarch64-feature-pac.s
+++ b/lld/test/ELF/aarch64-feature-pac.s
@@ -32,6 +32,10 @@
# NOPAC-NEXT: add x16, x16, #968
# NOPAC-NEXT: br x17
+# SOGOTPLT: Hex dump of section '.got.plt':
+# SOGOTPLT-NEXT: 0x000303b0 00000000 00000000 00000000 00000000
+# SOGOTPLT-NEXT: 0x000303c0 00000000 00000000 d0020100 00000000
+
# NOPACDYN-NOT: 0x0000000070000001 (AARCH64_BTI_PLT)
# NOPACDYN-NOT: 0x0000000070000003 (AARCH64_PAC_PLT)
@@ -41,9 +45,7 @@
# RUN: llvm-readelf -x .got.plt %t.so | FileCheck --check-prefix SOGOTPLT2 %s
# RUN: llvm-readelf --dynamic-table %t.so | FileCheck --check-prefix PACDYN %s
-## PAC has no effect on PLT[0], for PLT[N] autia1716 is used to authenticate
-## the address in x17 (context in x16) before branching to it. The dynamic
-## loader is responsible for calling pacia1716 on the entry.
+## PAC has no effect on PLT[0], for PLT[N].
# PACSO: 0000000000010348 func2:
# PACSO-NEXT: 10348: bl #56 <func3 at plt>
# PACSO-NEXT: ret
@@ -53,32 +55,26 @@
# PACSO: 0000000000010360 .plt:
# PACSO-NEXT: 10360: stp x16, x30, [sp, #-16]!
# PACSO-NEXT: adrp x16, #131072
-# PACSO-NEXT: ldr x17, [x16, #1144]
-# PACSO-NEXT: add x16, x16, #1144
+# PACSO-NEXT: ldr x17, [x16, #1120]
+# PACSO-NEXT: add x16, x16, #1120
# PACSO-NEXT: br x17
# PACSO-NEXT: nop
# PACSO-NEXT: nop
# PACSO-NEXT: nop
# PACSO: 0000000000010380 func3 at plt:
# PACSO-NEXT: 10380: adrp x16, #131072
-# PACSO-NEXT: ldr x17, [x16, #1152]
-# PACSO-NEXT: add x16, x16, #1152
-# PACSO-NEXT: autia1716
+# PACSO-NEXT: ldr x17, [x16, #1128]
+# PACSO-NEXT: add x16, x16, #1128
# PACSO-NEXT: br x17
-# PACSO-NEXT: nop
-
-# SOGOTPLT: Hex dump of section '.got.plt':
-# SOGOTPLT-NEXT: 0x000303b0 00000000 00000000 00000000 00000000
-# SOGOTPLT-NEXT: 0x000303c0 00000000 00000000 d0020100 00000000
# SOGOTPLT2: Hex dump of section '.got.plt':
-# SOGOTPLT2-NEXT: 0x00030468 00000000 00000000 00000000 00000000
-# SOGOTPLT2-NEXT: 0x00030478 00000000 00000000 60030100 00000000
+# SOGOTPLT2-NEXT: 0x00030450 00000000 00000000 00000000 00000000
+# SOGOTPLT2-NEXT: 0x00030460 00000000 00000000 60030100 00000000
# PACPROP: Properties: aarch64 feature: PAC
# PACDYN-NOT: 0x0000000070000001 (AARCH64_BTI_PLT)
-# PACDYN: 0x0000000070000003 (AARCH64_PAC_PLT)
+# PACDYN-NOT: 0x0000000070000003 (AARCH64_PAC_PLT)
## Turn on PAC entries with the -z pac-plt command line option. There are no
## warnings in this case as the choice to use PAC in PLT entries is orthogonal
@@ -87,7 +83,7 @@
# RUN: ld.lld %t.o %t2.o -z pac-plt %t.so -o %tpacplt.exe
# RUN: llvm-readelf -n %tpacplt.exe | FileCheck --check-prefix=PACPROP %s
-# RUN: llvm-readelf --dynamic-table %tpacplt.exe | FileCheck --check-prefix PACDYN %s
+# RUN: llvm-readelf --dynamic-table %tpacplt.exe | FileCheck --check-prefix PACDYN2 %s
# RUN: llvm-objdump -d -mattr=+v8.3a --no-show-raw-insn %tpacplt.exe | FileCheck --check-prefix PACPLT %s
# PACPLT: Disassembly of section .text:
@@ -114,6 +110,9 @@
# PACPLT-NEXT: br x17
# PACPLT-NEXT: nop
+# PACDYN2-NOT: 0x0000000070000001 (AARCH64_BTI_PLT)
+# PACDYN2: 0x0000000070000003 (AARCH64_PAC_PLT)
+
.section ".note.gnu.property", "a"
.long 4
.long 0x10
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