From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AB6701B374F; Thu, 4 Jul 2024 16:39:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720111151; cv=none; b=q9O05syLJ/k1TsjwrBD73qZtFK4IB+yo9mipKtIn+qpk/OHpOSbH27k80/dPNNqM1/kYgi8I5fI6w/G46/AhFvOMWZQIIkgL5ndJeBW9M70NznWdLJrlEvDry5FWlT4haetaqlQLoPBAMEy3DfvFIRqs+r4OpFNxjn3rZeNpHZc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720111151; c=relaxed/simple; bh=Bs5sRfDrSxaaIvkIerZLN3dXVAr5INLyWGwt4rreui8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=lRNYDasCHLMPfXPWIaoo63LFTibSETVicLn3fBO6cWocuijEid75B+X7bm7KEU5TCVL5RltbYDW7dn10GmAcJBTHyp1EwOScmf46ZXing5jdLtVlcgKf8MOBt3B/TICFzttNZO7fZFlBTHUrA4KBX9n6rPGil5pS8pOm/7rsUXY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WNI0T/Pf; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="WNI0T/Pf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DEF8EC4AF0E; Thu, 4 Jul 2024 16:39:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1720111151; bh=Bs5sRfDrSxaaIvkIerZLN3dXVAr5INLyWGwt4rreui8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=WNI0T/Pffc6B3iSRMiZPlG8zDplMPuzvnoqo0GJ334XC5B2XgSX031T6dBiIB7fuv eCAhTZmTJvoPNopI0xgqtjIPCOBhvjQHSCjQkfpDk5ONQMxD2McfzTsFjK6BBS+COs opCHlYojwbsYmhXsaDZUrfnPC5xX1Y364/AYT7PvYCq6O3bBhsLdVBzNrGJENi+Wth K0jocA5kxTwj15uVdaZp7gJ8h408lZMfqOiLZlUuO3AYbL8u4P7J5CGouOdL+HDR8h WXpVmafGFur+LmEx6Z1Q/MvOHSDWJvJZ2l+xWLIo0CVFWvX7NRDxskKvr7/Zwykx3a Kd9asDK6i+/lA== Date: Thu, 4 Jul 2024 09:39:08 -0700 From: Nathan Chancellor To: Alice Ryhl Cc: Catalin Marinas , Will Deacon , Jamie Cunliffe , Sami Tolvanen , Masahiro Yamada , Nicolas Schier , Ard Biesheuvel , Marc Zyngier , Mark Rutland , Mark Brown , Nick Desaulniers , Kees Cook , Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?iso-8859-1?Q?Bj=F6rn?= Roy Baron , Benno Lossin , Andreas Hindborg , Valentin Obst , linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, rust-for-linux@vger.kernel.org Subject: Re: [PATCH v3 2/2] rust: add flags for shadow call stack sanitizer Message-ID: <20240704163908.GA1394865@thelio-3990X> References: <20240704-shadow-call-stack-v3-0-d11c7a6ebe30@google.com> <20240704-shadow-call-stack-v3-2-d11c7a6ebe30@google.com> Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240704-shadow-call-stack-v3-2-d11c7a6ebe30@google.com> Hi Alice, On Thu, Jul 04, 2024 at 03:07:58PM +0000, Alice Ryhl wrote: > As of rustc 1.80.0, the Rust compiler supports the -Zfixed-x18 flag, so > we can now use Rust with the shadow call stack sanitizer. > > On older versions of Rust, it is possible to use shadow call stack by > passing -Ctarget-feature=+reserve-x18 instead of -Zfixed-x18. However, > this flag emits a warning, so this patch does not add support for that. > > 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. See [2] for the ^ this should be [1]? > feature request to add this. Kconfig is not configured to reject this > configuration because that leads to cyclic Kconfig rules. While it probably does not matter much given Rust for Linux is still "in the works", I think it would be good to avoid these build failures. Perhaps something like this could work (which basically just forces on UNWIND_PATCH_PAC_INTO_SCS when Rust is enabled). diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 5d91259ee7b5..a9f08a2bd1c6 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -89,7 +89,7 @@ config ARM64 select ARCH_SUPPORTS_DEBUG_PAGEALLOC select ARCH_SUPPORTS_HUGETLBFS select ARCH_SUPPORTS_MEMORY_FAILURE - select ARCH_SUPPORTS_SHADOW_CALL_STACK if CC_HAVE_SHADOW_CALL_STACK + select ARCH_SUPPORTS_SHADOW_CALL_STACK if CC_HAVE_SHADOW_CALL_STACK && (!RUST || CAN_UNWIND_PATCH_PAC_INTO_SCS) select ARCH_SUPPORTS_LTO_CLANG if CPU_LITTLE_ENDIAN select ARCH_SUPPORTS_LTO_CLANG_THIN select ARCH_SUPPORTS_CFI_CLANG @@ -2262,12 +2262,16 @@ config STACKPROTECTOR_PER_TASK def_bool y depends on STACKPROTECTOR && CC_HAVE_STACKPROTECTOR_SYSREG -config UNWIND_PATCH_PAC_INTO_SCS - bool "Enable shadow call stack dynamically using code patching" +config CAN_UNWIND_PATCH_PAC_INTO_SCS + def_bool y # needs Clang with https://github.com/llvm/llvm-project/commit/de07cde67b5d205d58690be012106022aea6d2b3 incorporated depends on CC_IS_CLANG && CLANG_VERSION >= 150000 depends on ARM64_PTR_AUTH_KERNEL && CC_HAS_BRANCH_PROT_PAC_RET - depends on SHADOW_CALL_STACK + +config UNWIND_PATCH_PAC_INTO_SCS + bool "Enable shadow call stack dynamically using code patching" if !RUST + depends on SHADOW_CALL_STACK && CAN_UNWIND_PATCH_PAC_INTO_SCS + default y if RUST select UNWIND_TABLES select DYNAMIC_SCS Otherwise, it might be good to wait to enable this until [1] is addressed, but I don't really feel that strongly about it. >From a Kconfig/Kbuild perspective, the rest of the patch seems fine. > Link: https://github.com/rust-lang/rust/issues/121972 [1] > Signed-off-by: Alice Ryhl > --- > Makefile | 1 + > arch/Kconfig | 2 +- > arch/arm64/Makefile | 3 +++ > 3 files changed, 5 insertions(+), 1 deletion(-) > > diff --git a/Makefile b/Makefile > index c11a10c8e710..4ae741601a1c 100644 > --- a/Makefile > +++ b/Makefile > @@ -945,6 +945,7 @@ 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/Kconfig b/arch/Kconfig > index 238448a9cb71..5a6e296df5e6 100644 > --- a/arch/Kconfig > +++ b/arch/Kconfig > @@ -690,7 +690,7 @@ config SHADOW_CALL_STACK > bool "Shadow Call Stack" > depends on ARCH_SUPPORTS_SHADOW_CALL_STACK > depends on DYNAMIC_FTRACE_WITH_ARGS || DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER > - depends on !RUST > + depends on !RUST || RUSTC_VERSION >= 108000 > depends on MMU > help > This option enables the compiler's Shadow Call Stack, which > diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile > index 3f0f35fd5bb7..bbf313ddd700 100644 > --- a/arch/arm64/Makefile > +++ b/arch/arm64/Makefile > @@ -57,9 +57,11 @@ 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 > +KBUILD_RUSTFLAGS += -Cforce-unwind-tables=y -Zuse-sync-unwind=n > endif > > ifeq ($(CONFIG_STACKPROTECTOR_PER_TASK),y) > @@ -114,6 +116,7 @@ endif > > ifeq ($(CONFIG_SHADOW_CALL_STACK), y) > KBUILD_CFLAGS += -ffixed-x18 > +KBUILD_RUSTFLAGS += -Zfixed-x18 > endif > > ifeq ($(CONFIG_CPU_BIG_ENDIAN), y) > > -- > 2.45.2.803.g4e1b14247a-goog >