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Pack relocations for Android API >= 28 #117624

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Dec 4, 2024
Merged

Pack relocations for Android API >= 28 #117624

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90e21e8
Add no-rosegment by default for API < 29.
hiraditya Nov 25, 2024
df367ed
Pack relocations for Android API >= 28
hiraditya Nov 25, 2024
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18 changes: 18 additions & 0 deletions clang/lib/Driver/ToolChains/Linux.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -256,6 +256,24 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
ExtraOpts.push_back("-z");
ExtraOpts.push_back("max-page-size=16384");
}
if (Triple.isAndroidVersionLT(29)) {
// https://github.com/android/ndk/issues/1196
// The unwinder used by the crash handler on versions of Android prior to
// API 29 did not correctly handle binaries built with rosegment, which is
// enabled by default for LLD. Android only supports LLD, so it's not an
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The NDK only provides LLD, but one can still use another linker via -fuse-ld, and this breaks that use case. And yes, there are people doing that.

// issue that this flag is not accepted by other linkers.
ExtraOpts.push_back("--no-rosegment");
}
if (!Triple.isAndroidVersionLT(28)) {
// Android supports relr packing starting with API 28 and had its own
// flavor (--pack-dyn-relocs=android) starting in API 23.
// TODO: It's possible to use both with --pack-dyn-relocs=android+relr,
// but we need to gather some data on the impact of that form before we
// can know if it's a good default.
// On the other hand, relr should always be an improvement.
ExtraOpts.push_back("--use-android-relr-tags");
ExtraOpts.push_back("--pack-dyn-relocs=relr");
}
}

if (GCCInstallation.getParentLibPath().contains("opt/rh/"))
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30 changes: 30 additions & 0 deletions clang/test/Driver/linux-ld.c
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Expand Up @@ -940,6 +940,36 @@
// CHECK-ANDROID-HASH-STYLE-M: "{{.*}}ld{{(.exe)?}}"
// CHECK-ANDROID-HASH-STYLE-M: "--hash-style=gnu"

// Check that we pass --no-rosegment for pre-29 Android versions and do not for
// 29+.
// RUN: %clang %s -### -o %t.o 2>&1 \
// RUN: --target=armv7-linux-android28 \
// RUN: | FileCheck --check-prefix=CHECK-ANDROID-ROSEGMENT-28 %s
// CHECK-ANDROID-ROSEGMENT-28: "{{.*}}ld{{(.exe)?}}"
// CHECK-ANDROID-ROSEGMENT-28: "--no-rosegment"
//
// RUN: %clang %s -### -o %t.o 2>&1 \
// RUN: --target=armv7-linux-android29 \
// RUN: | FileCheck --check-prefix=CHECK-ANDROID-ROSEGMENT-29 %s
// CHECK-ANDROID-ROSEGMENT-29: "{{.*}}ld{{(.exe)?}}"
// CHECK-ANDROID-ROSEGMENT-29-NOT: "--no-rosegment"

// Check that we pass --pack-dyn-relocs=relr for API 28+ and not before.
// RUN: %clang %s -### -o %t.o 2>&1 \
// RUN: --target=armv7-linux-android27 \
// RUN: | FileCheck --check-prefix=CHECK-ANDROID-RELR-27 %s
// CHECK-ANDROID-RELR-27: "{{.*}}ld{{(.exe)?}}"
// CHECK-ANDROID-RELR-27-NOT: "--pack-dyn-relocs=relr"
// CHECK-ANDROID-RELR-27-NOT: "--pack-dyn-relocs=android+relr"
//
// RUN: %clang %s -### -o %t.o 2>&1 \
// RUN: --target=armv7-linux-android28 \
// RUN: | FileCheck --check-prefix=CHECK-ANDROID-RELR-28 %s
// CHECK-ANDROID-RELR-28: "{{.*}}ld{{(.exe)?}}"
// CHECK-ANDROID-RELR-28: "--use-android-relr-tags"
// CHECK-ANDROID-RELR-28: "--pack-dyn-relocs=relr"
// CHECK-ANDROID-RELR-28-NOT: "--pack-dyn-relocs=android+relr"

// RUN: %clang -### %s -no-pie 2>&1 --target=mips64-linux-gnuabin32 \
// RUN: | FileCheck --check-prefix=CHECK-MIPS64EL-GNUABIN32 %s
// CHECK-MIPS64EL-GNUABIN32: "{{.*}}ld{{(.exe)?}}"
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