From 263770649df83141b55bbb9b154e41de7b9ce9dc Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Mon, 4 Mar 2024 13:17:03 +0000 Subject: [PATCH] FROMLIST: rust: add flags for shadow call stack sanitizer Add flags to support the shadow call stack sanitizer, both in the dynamic and non-dynamic modes. Right now, the compiler will emit the warning "unknown feature specified for `-Ctarget-feature`: `reserve-x18`". However, the compiler still passes it to the codegen backend, so the flag will work just fine. Once rustc starts recognizing the flag (or provides another way to enable the feature), it will stop emitting this warning. See [1] for the relevant issue. Currently, the compiler thinks that the aarch64-unknown-none target doesn't support -Zsanitizer=shadow-call-stack, so the build will fail if you enable shadow call stack in non-dynamic mode. However, I still think it is reasonable to add the flag now, as it will at least fail the build when using an invalid configuration, until the Rust compiler is fixed to list -Zsanitizer=shadow-call-stack as supported for the target. See [2] for the feature request to add this. I have tested this change with Rust Binder on an Android device using CONFIG_DYNAMIC_SCS. Without the -Ctarget-feature=+reserve-x18 flag, the phone crashes immediately on boot, and with the flag, the phone appears to work normally. This contains a TODO to add the -Zuse-sync-unwind=n flag. The flag defaults to n, so it isn't a problem today, but the flag is unstable, so the default could change in a future compiler release. Link: https://github.com/rust-lang/rust/issues/121970 [1] Link: https://github.com/rust-lang/rust/issues/121972 [2] Signed-off-by: Alice Ryhl Bug: 328033850 Link: https://lore.kernel.org/rust-for-linux/20240305-shadow-call-stack-v2-1-c7b4a3f4d616@google.com/ Change-Id: Ia55287e1ed6da2d5d8d3d6414f2d9a0fc7d23e81 Signed-off-by: Alice Ryhl --- Makefile | 1 + arch/arm64/Makefile | 4 ++++ 2 files changed, 5 insertions(+) diff --git a/Makefile b/Makefile index 34b68bd1df01..604d992ad6ec 100644 --- a/Makefile +++ b/Makefile @@ -952,6 +952,7 @@ ifdef CONFIG_SHADOW_CALL_STACK ifndef CONFIG_DYNAMIC_SCS CC_FLAGS_SCS := -fsanitize=shadow-call-stack KBUILD_CFLAGS += $(CC_FLAGS_SCS) +KBUILD_RUSTFLAGS += -Zsanitizer=shadow-call-stack endif export CC_FLAGS_SCS endif diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index c6209c7f7d5e..03211b41aa15 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -48,9 +48,12 @@ KBUILD_AFLAGS += $(call cc-option,-mabi=lp64) ifneq ($(CONFIG_UNWIND_TABLES),y) KBUILD_CFLAGS += -fno-asynchronous-unwind-tables -fno-unwind-tables KBUILD_AFLAGS += -fno-asynchronous-unwind-tables -fno-unwind-tables +KBUILD_RUSTFLAGS += -Cforce-unwind-tables=n else KBUILD_CFLAGS += -fasynchronous-unwind-tables KBUILD_AFLAGS += -fasynchronous-unwind-tables +# TODO: Pass -Zuse-sync-unwind=n once we upgrade to Rust 1.77.0 +KBUILD_RUSTFLAGS += -Cforce-unwind-tables=y endif ifeq ($(CONFIG_STACKPROTECTOR_PER_TASK),y) @@ -103,6 +106,7 @@ endif ifeq ($(CONFIG_SHADOW_CALL_STACK), y) KBUILD_CFLAGS += -ffixed-x18 +KBUILD_RUSTFLAGS += -Ctarget-feature=+reserve-x18 endif ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)