From: Nathan Chancellor <nathan@kernel.org> To: Sami Tolvanen <samitolvanen@google.com> Cc: Kees Cook <keescook@chromium.org>, Catalin Marinas <catalin.marinas@arm.com>, Mark Rutland <mark.rutland@arm.com>, Masahiro Yamada <masahiroy@kernel.org>, Nick Desaulniers <ndesaulniers@google.com>, Will Deacon <will@kernel.org>, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH v2] cfi: Use __builtin_function_start Date: Tue, 5 Apr 2022 15:20:39 -0700 [thread overview] Message-ID: <YkzAtwW4KtZ22ySb@thelio-3990X> (raw) In-Reply-To: <20220405221618.633743-1-samitolvanen@google.com> On Tue, Apr 05, 2022 at 03:16:18PM -0700, Sami Tolvanen wrote: > Clang 14 added support for the __builtin_function_start function, > which allows us to implement the function_nocfi macro without > architecture-specific inline assembly and in a way that also works > with static initializers. > > Change CONFIG_CFI_CLANG to depend on Clang >= 14, define > function_nocfi using __builtin_function_start, and remove the arm64 > inline assembly implementation. > > Link: https://github.com/llvm/llvm-project/commit/ec2e26eaf63558934f5b73a6e530edc453cf9508 > Link: https://github.com/ClangBuiltLinux/linux/issues/1353 > Signed-off-by: Sami Tolvanen <samitolvanen@google.com> > Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > Reviewed-by: Mark Rutland <mark.rutland@arm.com> > Tested-by: Mark Rutland <mark.rutland@arm.com> > Acked-by: Will Deacon <will@kernel.org> # arm64 Reviewed-by: Nathan Chancellor <nathan@kernel.org> > --- > v2: > - Changed CFI_CLANG to depend on Clang 14 instead of > __builtin_function_start. > - Squashed all three patches into one. > > --- > arch/Kconfig | 5 +---- > arch/arm64/include/asm/compiler.h | 16 ---------------- > include/linux/compiler-clang.h | 10 ++++++++++ > 3 files changed, 11 insertions(+), 20 deletions(-) > > diff --git a/arch/Kconfig b/arch/Kconfig > index 29b0167c088b..c1627bce4a3a 100644 > --- a/arch/Kconfig > +++ b/arch/Kconfig > @@ -723,10 +723,7 @@ config ARCH_SUPPORTS_CFI_CLANG > config CFI_CLANG > bool "Use Clang's Control Flow Integrity (CFI)" > depends on LTO_CLANG && ARCH_SUPPORTS_CFI_CLANG > - # Clang >= 12: > - # - https://bugs.llvm.org/show_bug.cgi?id=46258 > - # - https://bugs.llvm.org/show_bug.cgi?id=47479 > - depends on CLANG_VERSION >= 120000 > + depends on CLANG_VERSION >= 140000 > select KALLSYMS > help > This option enables Clang’s forward-edge Control Flow Integrity > diff --git a/arch/arm64/include/asm/compiler.h b/arch/arm64/include/asm/compiler.h > index dc3ea4080e2e..6fb2e6bcc392 100644 > --- a/arch/arm64/include/asm/compiler.h > +++ b/arch/arm64/include/asm/compiler.h > @@ -23,20 +23,4 @@ > #define __builtin_return_address(val) \ > (void *)(ptrauth_clear_pac((unsigned long)__builtin_return_address(val))) > > -#ifdef CONFIG_CFI_CLANG > -/* > - * With CONFIG_CFI_CLANG, the compiler replaces function address > - * references with the address of the function's CFI jump table > - * entry. The function_nocfi macro always returns the address of the > - * actual function instead. > - */ > -#define function_nocfi(x) ({ \ > - void *addr; \ > - asm("adrp %0, " __stringify(x) "\n\t" \ > - "add %0, %0, :lo12:" __stringify(x) \ > - : "=r" (addr)); \ > - addr; \ > -}) > -#endif > - > #endif /* __ASM_COMPILER_H */ > diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h > index babb1347148c..c84fec767445 100644 > --- a/include/linux/compiler-clang.h > +++ b/include/linux/compiler-clang.h > @@ -69,6 +69,16 @@ > #define __nocfi __attribute__((__no_sanitize__("cfi"))) > #define __cficanonical __attribute__((__cfi_canonical_jump_table__)) > > +#if defined(CONFIG_CFI_CLANG) > +/* > + * With CONFIG_CFI_CLANG, the compiler replaces function address > + * references with the address of the function's CFI jump table > + * entry. The function_nocfi macro always returns the address of the > + * actual function instead. > + */ > +#define function_nocfi(x) __builtin_function_start(x) > +#endif > + > /* > * Turn individual warnings and errors on and off locally, depending > * on version. > -- > 2.35.1.1094.g7c7d902a7c-goog >
WARNING: multiple messages have this Message-ID (diff)
From: Nathan Chancellor <nathan@kernel.org> To: Sami Tolvanen <samitolvanen@google.com> Cc: Kees Cook <keescook@chromium.org>, Catalin Marinas <catalin.marinas@arm.com>, Mark Rutland <mark.rutland@arm.com>, Masahiro Yamada <masahiroy@kernel.org>, Nick Desaulniers <ndesaulniers@google.com>, Will Deacon <will@kernel.org>, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH v2] cfi: Use __builtin_function_start Date: Tue, 5 Apr 2022 15:20:39 -0700 [thread overview] Message-ID: <YkzAtwW4KtZ22ySb@thelio-3990X> (raw) In-Reply-To: <20220405221618.633743-1-samitolvanen@google.com> On Tue, Apr 05, 2022 at 03:16:18PM -0700, Sami Tolvanen wrote: > Clang 14 added support for the __builtin_function_start function, > which allows us to implement the function_nocfi macro without > architecture-specific inline assembly and in a way that also works > with static initializers. > > Change CONFIG_CFI_CLANG to depend on Clang >= 14, define > function_nocfi using __builtin_function_start, and remove the arm64 > inline assembly implementation. > > Link: https://github.com/llvm/llvm-project/commit/ec2e26eaf63558934f5b73a6e530edc453cf9508 > Link: https://github.com/ClangBuiltLinux/linux/issues/1353 > Signed-off-by: Sami Tolvanen <samitolvanen@google.com> > Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > Reviewed-by: Mark Rutland <mark.rutland@arm.com> > Tested-by: Mark Rutland <mark.rutland@arm.com> > Acked-by: Will Deacon <will@kernel.org> # arm64 Reviewed-by: Nathan Chancellor <nathan@kernel.org> > --- > v2: > - Changed CFI_CLANG to depend on Clang 14 instead of > __builtin_function_start. > - Squashed all three patches into one. > > --- > arch/Kconfig | 5 +---- > arch/arm64/include/asm/compiler.h | 16 ---------------- > include/linux/compiler-clang.h | 10 ++++++++++ > 3 files changed, 11 insertions(+), 20 deletions(-) > > diff --git a/arch/Kconfig b/arch/Kconfig > index 29b0167c088b..c1627bce4a3a 100644 > --- a/arch/Kconfig > +++ b/arch/Kconfig > @@ -723,10 +723,7 @@ config ARCH_SUPPORTS_CFI_CLANG > config CFI_CLANG > bool "Use Clang's Control Flow Integrity (CFI)" > depends on LTO_CLANG && ARCH_SUPPORTS_CFI_CLANG > - # Clang >= 12: > - # - https://bugs.llvm.org/show_bug.cgi?id=46258 > - # - https://bugs.llvm.org/show_bug.cgi?id=47479 > - depends on CLANG_VERSION >= 120000 > + depends on CLANG_VERSION >= 140000 > select KALLSYMS > help > This option enables Clang’s forward-edge Control Flow Integrity > diff --git a/arch/arm64/include/asm/compiler.h b/arch/arm64/include/asm/compiler.h > index dc3ea4080e2e..6fb2e6bcc392 100644 > --- a/arch/arm64/include/asm/compiler.h > +++ b/arch/arm64/include/asm/compiler.h > @@ -23,20 +23,4 @@ > #define __builtin_return_address(val) \ > (void *)(ptrauth_clear_pac((unsigned long)__builtin_return_address(val))) > > -#ifdef CONFIG_CFI_CLANG > -/* > - * With CONFIG_CFI_CLANG, the compiler replaces function address > - * references with the address of the function's CFI jump table > - * entry. The function_nocfi macro always returns the address of the > - * actual function instead. > - */ > -#define function_nocfi(x) ({ \ > - void *addr; \ > - asm("adrp %0, " __stringify(x) "\n\t" \ > - "add %0, %0, :lo12:" __stringify(x) \ > - : "=r" (addr)); \ > - addr; \ > -}) > -#endif > - > #endif /* __ASM_COMPILER_H */ > diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h > index babb1347148c..c84fec767445 100644 > --- a/include/linux/compiler-clang.h > +++ b/include/linux/compiler-clang.h > @@ -69,6 +69,16 @@ > #define __nocfi __attribute__((__no_sanitize__("cfi"))) > #define __cficanonical __attribute__((__cfi_canonical_jump_table__)) > > +#if defined(CONFIG_CFI_CLANG) > +/* > + * With CONFIG_CFI_CLANG, the compiler replaces function address > + * references with the address of the function's CFI jump table > + * entry. The function_nocfi macro always returns the address of the > + * actual function instead. > + */ > +#define function_nocfi(x) __builtin_function_start(x) > +#endif > + > /* > * Turn individual warnings and errors on and off locally, depending > * on version. > -- > 2.35.1.1094.g7c7d902a7c-goog > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2022-04-05 22:20 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-04-05 22:16 [PATCH v2] cfi: Use __builtin_function_start Sami Tolvanen 2022-04-05 22:16 ` Sami Tolvanen 2022-04-05 22:20 ` Nathan Chancellor [this message] 2022-04-05 22:20 ` Nathan Chancellor 2022-04-13 19:26 ` Kees Cook 2022-04-13 19:26 ` Kees Cook
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