diff options
| author | Zhenzhong Duan <zhenzhong.duan@oracle.com> | 2018-11-02 01:45:41 -0700 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-11-28 11:57:03 +0100 |
| commit | 4cd24de3a0980bf3100c9dcb08ef65ca7c31af48 (patch) | |
| tree | e8358f10ec5689cdda1d7ad33491c607d15766c6 /arch | |
| parent | 2e6e902d185027f8e3cb8b7305238f7e35d6a436 (diff) | |
x86/retpoline: Make CONFIG_RETPOLINE depend on compiler support
Since retpoline capable compilers are widely available, make
CONFIG_RETPOLINE hard depend on the compiler capability.
Break the build when CONFIG_RETPOLINE is enabled and the compiler does not
support it. Emit an error message in that case:
"arch/x86/Makefile:226: *** You are building kernel with non-retpoline
compiler, please update your compiler.. Stop."
[dwmw: Fail the build with non-retpoline compiler]
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Borislav Petkov <bp@suse.de>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: <srinivas.eeda@oracle.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/cca0cb20-f9e2-4094-840b-fb0f8810cd34@default
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/Kconfig | 4 | ||||
| -rw-r--r-- | arch/x86/Makefile | 5 | ||||
| -rw-r--r-- | arch/x86/include/asm/nospec-branch.h | 10 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/bugs.c | 2 |
4 files changed, 10 insertions, 11 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 9d734f3c8234..b5286ad2a982 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -444,10 +444,6 @@ config RETPOLINE branches. Requires a compiler with -mindirect-branch=thunk-extern support for full protection. The kernel may run slower. - Without compiler support, at least indirect branches in assembler - code are eliminated. Since this includes the syscall entry path, - it is not entirely pointless. - config INTEL_RDT bool "Intel Resource Director Technology support" depends on X86 && CPU_SUP_INTEL diff --git a/arch/x86/Makefile b/arch/x86/Makefile index 88398fdf8129..f5d7f4134524 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -220,9 +220,10 @@ KBUILD_CFLAGS += -fno-asynchronous-unwind-tables # Avoid indirect branches in kernel to deal with Spectre ifdef CONFIG_RETPOLINE -ifneq ($(RETPOLINE_CFLAGS),) - KBUILD_CFLAGS += $(RETPOLINE_CFLAGS) -DRETPOLINE +ifeq ($(RETPOLINE_CFLAGS),) + $(error You are building kernel with non-retpoline compiler, please update your compiler.) endif + KBUILD_CFLAGS += $(RETPOLINE_CFLAGS) endif archscripts: scripts_basic diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index 80dc14422495..8b09cbb2d52c 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -162,11 +162,12 @@ _ASM_PTR " 999b\n\t" \ ".popsection\n\t" -#if defined(CONFIG_X86_64) && defined(RETPOLINE) +#ifdef CONFIG_RETPOLINE +#ifdef CONFIG_X86_64 /* - * Since the inline asm uses the %V modifier which is only in newer GCC, - * the 64-bit one is dependent on RETPOLINE not CONFIG_RETPOLINE. + * Inline asm uses the %V modifier which is only in newer GCC + * which is ensured when CONFIG_RETPOLINE is defined. */ # define CALL_NOSPEC \ ANNOTATE_NOSPEC_ALTERNATIVE \ @@ -181,7 +182,7 @@ X86_FEATURE_RETPOLINE_AMD) # define THUNK_TARGET(addr) [thunk_target] "r" (addr) -#elif defined(CONFIG_X86_32) && defined(CONFIG_RETPOLINE) +#else /* CONFIG_X86_32 */ /* * For i386 we use the original ret-equivalent retpoline, because * otherwise we'll run out of registers. We don't care about CET @@ -211,6 +212,7 @@ X86_FEATURE_RETPOLINE_AMD) # define THUNK_TARGET(addr) [thunk_target] "rm" (addr) +#endif #else /* No retpoline for C / inline asm */ # define CALL_NOSPEC "call *%[thunk_target]\n" # define THUNK_TARGET(addr) [thunk_target] "rm" (addr) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index c37e66e493bf..d0108fb6e4dd 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -252,7 +252,7 @@ static void __init spec2_print_if_secure(const char *reason) static inline bool retp_compiler(void) { - return __is_defined(RETPOLINE); + return __is_defined(CONFIG_RETPOLINE); } static inline bool match_option(const char *arg, int arglen, const char *opt) |