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 6B51B13B2AC; Tue, 27 Feb 2024 14:06:24 +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=1709042784; cv=none; b=EqUsHfhczbb2rsJDivCyfurkqq39wlGWfCZ/LWiYgoQ50kYSEOQbw0NYncZDfOH4O498EDd0wyY4Fd8Ll+Qt6LI+fChY3x1MIuSRMM24i82M82FkncIqrEmjiG49gpTIWPCwnceYG6GT6MMUAwbwygI7Whk4ZZlXpWIQFI6pmCA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709042784; c=relaxed/simple; bh=tySg+y0VczgHeB287gJyyeWBiVVZUMppCkIkgi9NP4U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=euAgBC2NP/Mi5huEur38LEcDjbADhe3eIehbJdKCGkapFT4PJc1FR7BWs5waxQtofJxgVpwPaFgcVcB1D3bvfncSH6oRRTKKyuzA98UU5vtK/bclrJoz2h2+pbcVbfJ0SqB7dvH0jtlSeWI7NHmYsgPhf5X6mw2aFBcH7MnNch4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ZkFuqjoL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="ZkFuqjoL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EB5CBC433F1; Tue, 27 Feb 2024 14:06:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1709042784; bh=tySg+y0VczgHeB287gJyyeWBiVVZUMppCkIkgi9NP4U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZkFuqjoLWxHfl1DvNItlVIF3OcdLy7wLkttIyg7TwEhq9UHr0G/25+i9tuNVIV3Gc ADrHr3BHAHEi1jT+116jFMNRVMWkpwwZfU6jxnseBFOXWNOMqaHsljeqLGQqQnjAiJ nAiWsE2P5RdfGv3ppzG+fe6NZIkanuHmBy3LoINA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Peter Zijlstra (Intel)" , Thomas Gleixner , "Borislav Petkov (AMD)" Subject: [PATCH 5.15 092/245] x86/returnthunk: Allow different return thunks Date: Tue, 27 Feb 2024 14:24:40 +0100 Message-ID: <20240227131618.213909379@linuxfoundation.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240227131615.098467438@linuxfoundation.org> References: <20240227131615.098467438@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Peter Zijlstra Upstream commit: 770ae1b709528a6a173b5c7b183818ee9b45e376 In preparation for call depth tracking on Intel SKL CPUs, make it possible to patch in a SKL specific return thunk. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20220915111147.680469665@infradead.org Signed-off-by: Borislav Petkov (AMD) Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/nospec-branch.h | 6 ++++++ arch/x86/kernel/alternative.c | 19 ++++++++++++++----- arch/x86/kernel/cpu/bugs.c | 2 ++ arch/x86/kernel/ftrace.c | 2 +- arch/x86/kernel/static_call.c | 2 +- arch/x86/net/bpf_jit_comp.c | 2 +- 6 files changed, 25 insertions(+), 8 deletions(-) --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -207,6 +207,12 @@ extern void srso_alias_untrain_ret(void) extern void entry_untrain_ret(void); extern void entry_ibpb(void); +#ifdef CONFIG_CALL_THUNKS +extern void (*x86_return_thunk)(void); +#else +#define x86_return_thunk (&__x86_return_thunk) +#endif + #ifdef CONFIG_RETPOLINE typedef u8 retpoline_thunk_t[RETPOLINE_THUNK_SIZE]; --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -521,6 +521,11 @@ void __init_or_module noinline apply_ret } #ifdef CONFIG_RETHUNK + +#ifdef CONFIG_CALL_THUNKS +void (*x86_return_thunk)(void) __ro_after_init = &__x86_return_thunk; +#endif + /* * Rewrite the compiler generated return thunk tail-calls. * @@ -536,14 +541,18 @@ static int patch_return(void *addr, stru { int i = 0; - if (cpu_feature_enabled(X86_FEATURE_RETHUNK)) - return -1; - - bytes[i++] = RET_INSN_OPCODE; + if (cpu_feature_enabled(X86_FEATURE_RETHUNK)) { + if (x86_return_thunk == __x86_return_thunk) + return -1; + + i = JMP32_INSN_SIZE; + __text_gen_insn(bytes, JMP32_INSN_OPCODE, addr, x86_return_thunk, i); + } else { + bytes[i++] = RET_INSN_OPCODE; + } for (; i < insn->length;) bytes[i++] = INT3_INSN_OPCODE; - return i; } --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -62,7 +62,9 @@ EXPORT_SYMBOL_GPL(x86_pred_cmd); static DEFINE_MUTEX(spec_ctrl_mutex); +#ifdef CONFIG_CALL_THUNKS void (*x86_return_thunk)(void) __ro_after_init = &__x86_return_thunk; +#endif /* Update SPEC_CTRL MSR and its cached copy unconditionally */ static void update_spec_ctrl(u64 val) --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -368,7 +368,7 @@ create_trampoline(struct ftrace_ops *ops ip = trampoline + size; if (cpu_feature_enabled(X86_FEATURE_RETHUNK)) - __text_gen_insn(ip, JMP32_INSN_OPCODE, ip, &__x86_return_thunk, JMP32_INSN_SIZE); + __text_gen_insn(ip, JMP32_INSN_OPCODE, ip, x86_return_thunk, JMP32_INSN_SIZE); else memcpy(ip, retq, sizeof(retq)); --- a/arch/x86/kernel/static_call.c +++ b/arch/x86/kernel/static_call.c @@ -52,7 +52,7 @@ static void __ref __static_call_transfor case RET: if (cpu_feature_enabled(X86_FEATURE_RETHUNK)) - code = text_gen_insn(JMP32_INSN_OPCODE, insn, &__x86_return_thunk); + code = text_gen_insn(JMP32_INSN_OPCODE, insn, x86_return_thunk); else code = &retinsn; break; --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -411,7 +411,7 @@ static void emit_return(u8 **pprog, u8 * u8 *prog = *pprog; if (cpu_feature_enabled(X86_FEATURE_RETHUNK)) { - emit_jump(&prog, &__x86_return_thunk, ip); + emit_jump(&prog, x86_return_thunk, ip); } else { EMIT1(0xC3); /* ret */ if (IS_ENABLED(CONFIG_SLS))