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 17B6F3D74 for ; Mon, 21 Nov 2022 12:44:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7CC11C433C1; Mon, 21 Nov 2022 12:44:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1669034687; bh=0q0Psi7fyKyo3QGbCxCqGfT4LqjyRduaugNxMpHWhUg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cHhjglSSR2v2ezqZoR59nGnAV5V9KnJ/yiQgRkcgkjHAdvcLdogKkvdAItiKW3YPA eSOLWPih4NrEI6p1/C+xc8otXYWCwvtpXyYNuLzdowL2ycEd9moppgzWKr/hNPN1bU indnmdYP02BIUPGZalQKVH2a2TZarnSCM1EjYFG0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Josh Poimboeuf , "Peter Zijlstra (Intel)" , Borislav Petkov , Thadeu Lima de Souza Cascardo , Suleiman Souhlal Subject: [PATCH 4.19 20/34] x86/speculation: Fix RSB filling with CONFIG_RETPOLINE=n Date: Mon, 21 Nov 2022 13:43:42 +0100 Message-Id: <20221121124151.615281027@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221121124150.886779344@linuxfoundation.org> References: <20221121124150.886779344@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Josh Poimboeuf commit b2620facef4889fefcbf2e87284f34dcd4189bce upstream. If a kernel is built with CONFIG_RETPOLINE=n, but the user still wants to mitigate Spectre v2 using IBRS or eIBRS, the RSB filling will be silently disabled. There's nothing retpoline-specific about RSB buffer filling. Remove the CONFIG_RETPOLINE guards around it. Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Borislav Petkov Signed-off-by: Thadeu Lima de Souza Cascardo Signed-off-by: Suleiman Souhlal Signed-off-by: Greg Kroah-Hartman --- arch/x86/entry/entry_32.S | 2 -- arch/x86/entry/entry_64.S | 2 -- arch/x86/include/asm/nospec-branch.h | 2 -- 3 files changed, 6 deletions(-) --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -643,7 +643,6 @@ ENTRY(__switch_to_asm) movl %ebx, PER_CPU_VAR(stack_canary)+stack_canary_offset #endif -#ifdef CONFIG_RETPOLINE /* * When switching from a shallower to a deeper call stack * the RSB may either underflow or use entries populated @@ -652,7 +651,6 @@ ENTRY(__switch_to_asm) * speculative execution to prevent attack. */ FILL_RETURN_BUFFER %ebx, RSB_CLEAR_LOOPS, X86_FEATURE_RSB_CTXSW -#endif /* restore callee-saved registers */ popfl --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -367,7 +367,6 @@ ENTRY(__switch_to_asm) movq %rbx, PER_CPU_VAR(irq_stack_union)+stack_canary_offset #endif -#ifdef CONFIG_RETPOLINE /* * When switching from a shallower to a deeper call stack * the RSB may either underflow or use entries populated @@ -376,7 +375,6 @@ ENTRY(__switch_to_asm) * speculative execution to prevent attack. */ FILL_RETURN_BUFFER %r12, RSB_CLEAR_LOOPS, X86_FEATURE_RSB_CTXSW -#endif /* restore callee-saved registers */ popfq --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -159,11 +159,9 @@ * monstrosity above, manually. */ .macro FILL_RETURN_BUFFER reg:req nr:req ftr:req -#ifdef CONFIG_RETPOLINE ALTERNATIVE "jmp .Lskip_rsb_\@", "", \ftr __FILL_RETURN_BUFFER(\reg,\nr,%_ASM_SP) .Lskip_rsb_\@: -#endif .endm #else /* __ASSEMBLY__ */