forked from luck/tmp_suning_uos_patched
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
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@ -444,10 +444,6 @@ config RETPOLINE
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branches. Requires a compiler with -mindirect-branch=thunk-extern
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support for full protection. The kernel may run slower.
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Without compiler support, at least indirect branches in assembler
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code are eliminated. Since this includes the syscall entry path,
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it is not entirely pointless.
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config INTEL_RDT
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bool "Intel Resource Director Technology support"
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depends on X86 && CPU_SUP_INTEL
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@ -220,9 +220,10 @@ KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
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# Avoid indirect branches in kernel to deal with Spectre
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ifdef CONFIG_RETPOLINE
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ifneq ($(RETPOLINE_CFLAGS),)
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KBUILD_CFLAGS += $(RETPOLINE_CFLAGS) -DRETPOLINE
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ifeq ($(RETPOLINE_CFLAGS),)
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$(error You are building kernel with non-retpoline compiler, please update your compiler.)
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endif
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KBUILD_CFLAGS += $(RETPOLINE_CFLAGS)
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endif
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archscripts: scripts_basic
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@ -162,11 +162,12 @@
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_ASM_PTR " 999b\n\t" \
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".popsection\n\t"
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#if defined(CONFIG_X86_64) && defined(RETPOLINE)
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#ifdef CONFIG_RETPOLINE
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#ifdef CONFIG_X86_64
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/*
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* Since the inline asm uses the %V modifier which is only in newer GCC,
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* the 64-bit one is dependent on RETPOLINE not CONFIG_RETPOLINE.
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* Inline asm uses the %V modifier which is only in newer GCC
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* which is ensured when CONFIG_RETPOLINE is defined.
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*/
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# define CALL_NOSPEC \
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ANNOTATE_NOSPEC_ALTERNATIVE \
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@ -181,7 +182,7 @@
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X86_FEATURE_RETPOLINE_AMD)
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# define THUNK_TARGET(addr) [thunk_target] "r" (addr)
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#elif defined(CONFIG_X86_32) && defined(CONFIG_RETPOLINE)
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#else /* CONFIG_X86_32 */
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/*
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* For i386 we use the original ret-equivalent retpoline, because
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* otherwise we'll run out of registers. We don't care about CET
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@ -211,6 +212,7 @@
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X86_FEATURE_RETPOLINE_AMD)
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# define THUNK_TARGET(addr) [thunk_target] "rm" (addr)
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#endif
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#else /* No retpoline for C / inline asm */
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# define CALL_NOSPEC "call *%[thunk_target]\n"
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# define THUNK_TARGET(addr) [thunk_target] "rm" (addr)
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@ -252,7 +252,7 @@ static void __init spec2_print_if_secure(const char *reason)
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static inline bool retp_compiler(void)
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{
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return __is_defined(RETPOLINE);
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return __is_defined(CONFIG_RETPOLINE);
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}
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static inline bool match_option(const char *arg, int arglen, const char *opt)
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@ -236,10 +236,8 @@ ifdef CONFIG_GCOV_KERNEL
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objtool_args += --no-unreachable
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endif
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ifdef CONFIG_RETPOLINE
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ifneq ($(RETPOLINE_CFLAGS),)
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objtool_args += --retpoline
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endif
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endif
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ifdef CONFIG_MODVERSIONS
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