From patchwork Sun Jul 19 15:50:33 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oscar Carter X-Patchwork-Id: 11672499 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4A755913 for ; Sun, 19 Jul 2020 15:52:15 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 7B7FA207EA for ; Sun, 19 Jul 2020 15:52:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=gmx.net header.i=@gmx.net header.b="dl9Qv6LY" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7B7FA207EA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=gmx.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-19395-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 11371 invoked by uid 550); 19 Jul 2020 15:52:10 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 11295 invoked from network); 19 Jul 2020 15:52:10 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1595173888; bh=N+UeP24eqVRjJpemOD2oTkwdHQmg8hfH9M861ui7lqc=; h=X-UI-Sender-Class:From:To:Cc:Subject:Date:In-Reply-To:References; b=dl9Qv6LYCoziMGrFyKXiJ98zjZduLijQGDv8AUlVyG2XYMNKbyCIzB3ZU9MIN8TWC wX0hb0X9KeR3RnLe4C2UMu7Z37kTBb0I5h5ABte1hdHrlKT98KrbAHE4JhmdsI+zju uRYM4Oa01/jk3J1cNjAxf1bVCkAvBUd+Nk51pbRo= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c From: Oscar Carter To: Steven Rostedt , Ingo Molnar , Kees Cook Cc: Oscar Carter , linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com, Jann Horn Subject: [PATCH v2 2/2] kernel/trace: Remove function callback casts Date: Sun, 19 Jul 2020 17:50:33 +0200 Message-Id: <20200719155033.24201-3-oscar.carter@gmx.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200719155033.24201-1-oscar.carter@gmx.com> References: <20200719155033.24201-1-oscar.carter@gmx.com> MIME-Version: 1.0 X-Provags-ID: V03:K1:yMLosVOVnTKjix38LbWzPsQaGdmB29CtaF2TTr1A9omeTBF3BUz ydqpg8sqfwZOnZwTkLl5iCEmMpusAAzkxpTlDAUTdo5iDEw5sH4XLsaGqm0lZ9pU/sMfEUG +2yMMw9pxfZYU5VoiKlxUf8sN5+WWgypIKJTPBr7Poz8TwnnwaNh/oX7m2TxnUdhj990rLQ CeyAxe4nR4uGMJqZbuI6A== X-Spam-Flag: NO X-UI-Out-Filterresults: notjunk:1;V03:K0:LdEQnRocgaA=:nSFO6IKDyDnCxNWHZorvAR BKP7FQFRcf4ATCdiommHAote0u+awdGJh6DzY4ep15XlBSULgWzdoZNyM/hcfAgaFszEw0c44 BMHLdOEHyZau9Zr6k8jgBsWrIQlQdjUoWj1f0iG8jKesizrNKsij3PvexG52Ejcd+UW31qkBk ZGdGL1ZjlhYtypfkWOeNIKUJ9l1i3rvze4wp0xbevyj+YUtlsvwSUtow8YIruOs5E5i3rbu/3 GYIrSvuaRPQ3D8ckL5UG9yQcm/ZElaaRiBNWo2JZTdxpa5dIWA068yG/9Plo9S8I7KA8Jvov0 G71gwJFxx+24M8Qk17M32esMG4kCQXDMj3ow8ycng7SxenRYgXW8O+kOloj4EQk1cHZvt8zfP 1Ok0sRMnHonR2k+GIJkAc8kyfGk2Ro+JKSIsyJeHPZYAL/20GdrRhcCncq8jvfXhPGGcjOipZ bONO+En/2r7ioS1FaRz9D+jKjHeECKt4LZsydYvoHWxCXzmrzHe61+DhvFz+Q7C9c0ESakdys li/eVxQ/DHwYdnX0X/81fPUoCjxxfkOfvIgkQKQfUVU0KyGWTBOCtAWxEAX15AIuEu/XZb0du vCOfQ3YaaEQfG73DyFmrxVccS9jbGXEdiNGDz7yxzUgJ2c3LICkGwQ2gB6i0tCglAWn+a2udB ABTl9aAGV6TEMuz6hFb0KajWvtRAeYWlfDT08UOyBiaxKsP9U5O0i2eN75Me4OMdHUri7Q5rw C8Uv3yW+hF7kwVayXDHMyIJaUjD5cx6G4pMw4zOWjvIeM2J20BI6+AhBNOmCDEmaujED5ZXEw uIM7emRkwo64K3vbflZbbtujLBVawdDxTTyTMBWftKuosZ283DwNrXao8R78qIWXxgBt6ff47 6C4lGHJZE54lDIGQOqgPidP7qVcczejAcXc0fAH+JpJG+GFIQFbQvrRSi4AnZi2hXvcPGifPI IQb0rpy1OcW4uWVmCc0Lmeq7UDzFnAm8vHfANtAftHJyjmUu2VmkhZftWxKxEIn5umuk9YOC/ oCpBl2l0l9o2i/g8ejI9NtklLxuLkg1ElIcmqBjXRNS0LjdFmNqc/UJqeFVIhg1S88Sz1XmFw SUUWkEHmN0DpRu9/tus74AhNcaT7AXC64hss2XG8VEATk76t7CsOaaeEChxlR5Ve946MFh0tr oFznsBP73HcIwX664soZySaVU54FE9hfxz7z9BcKB1rGSpTVN5COcUreQjoV9bzdrQpfIgHZ6 p6CpBJuXPEzPZ1z168MKlFnfqg/sr+n3UM4Zr6Q== In an effort to enable -Wcast-function-type in the top-level Makefile to support Control Flow Integrity builds, there are the need to remove all the function callback casts. ftrace_ops_list_func() can no longer be defined as ftrace_ops_no_ops(). The reason for ftrace_ops_no_ops() is to use that when an architecture calls ftrace_ops_list_func() with only two parameters (called from assembly). And to make sure there's no C side-effects, those archs call ftrace_ops_no_ops() which only has two parameters, as the function ftrace_ops_list_func() has four parameters. This patch removes the no longer needed function ftrace_ops_no_ops() and all the function callback casts using the previous defined ftrace_func union and the two function helpers called ftrace_set_ufunc() and ftrace_same_address_ufunc(). Signed-off-by: Oscar Carter --- kernel/trace/ftrace.c | 48 ++++++++++++++++++++++++++----------------- 1 file changed, 29 insertions(+), 19 deletions(-) -- 2.20.1 diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index fd8fbb422860..124ccf914657 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -143,9 +143,7 @@ static inline bool ftrace_same_address_ufunc(union ftrace_func *ufunc, return (ufunc->ops == func); } #else -/* See comment below, where ftrace_ops_list_func is defined */ -static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip); -#define ftrace_ops_list_func ((ftrace_func_t)ftrace_ops_no_ops) +static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip); static inline void ftrace_set_ufunc(union ftrace_func *ufunc, ftrace_func_no_ops_t func) @@ -198,22 +196,29 @@ static void ftrace_sync_ipi(void *data) smp_rmb(); } -static ftrace_func_t ftrace_ops_get_list_func(struct ftrace_ops *ops) +static union ftrace_func ftrace_ops_get_list_func(struct ftrace_ops *ops) { + union ftrace_func list_func; + /* * If this is a dynamic, RCU, or per CPU ops, or we force list func, * then it needs to call the list anyway. */ if (ops->flags & (FTRACE_OPS_FL_DYNAMIC | FTRACE_OPS_FL_RCU) || FTRACE_FORCE_LIST_FUNC) - return ftrace_ops_list_func; + ftrace_set_ufunc(&list_func, ftrace_ops_list_func); + else + list_func.ops = ftrace_ops_get_func(ops); - return ftrace_ops_get_func(ops); + return list_func; } static void update_ftrace_function(void) { - ftrace_func_t func; + union ftrace_func func; +#ifndef CONFIG_DYNAMIC_FTRACE + union ftrace_func tmp; +#endif /* * Prepare the ftrace_ops that the arch callback will use. @@ -225,7 +230,7 @@ static void update_ftrace_function(void) /* If there's no ftrace_ops registered, just call the stub function */ if (set_function_trace_op == &ftrace_list_end) { - func = ftrace_stub; + func.ops = ftrace_stub; /* * If we are at the end of the list and this ops is @@ -239,21 +244,21 @@ static void update_ftrace_function(void) } else { /* Just use the default ftrace_ops */ set_function_trace_op = &ftrace_list_end; - func = ftrace_ops_list_func; + ftrace_set_ufunc(&func, ftrace_ops_list_func); } update_function_graph_func(); /* If there's no change, then do nothing more here */ - if (ftrace_trace_function == func) + if (ftrace_trace_function == func.ops) return; /* * If we are using the list function, it doesn't care * about the function_trace_ops. */ - if (func == ftrace_ops_list_func) { - ftrace_trace_function = func; + if (ftrace_same_address_ufunc(&func, ftrace_ops_list_func)) { + ftrace_trace_function = func.ops; /* * Don't even bother setting function_trace_ops, * it would be racy to do so anyway. @@ -272,7 +277,9 @@ static void update_ftrace_function(void) * function we want, albeit indirectly, but it handles the * ftrace_ops and doesn't depend on function_trace_op. */ - ftrace_trace_function = ftrace_ops_list_func; + ftrace_set_ufunc(&tmp, ftrace_ops_list_func); + ftrace_trace_function = tmp.ops; + /* * Make sure all CPUs see this. Yes this is slow, but static * tracing is slow and nasty to have enabled. @@ -287,7 +294,7 @@ static void update_ftrace_function(void) /* OK, we are all set to update the ftrace_trace_function now! */ #endif /* !CONFIG_DYNAMIC_FTRACE */ - ftrace_trace_function = func; + ftrace_trace_function = func.ops; } static void add_ftrace_ops(struct ftrace_ops __rcu **list, @@ -2680,6 +2687,7 @@ void ftrace_modify_all_code(int command) int update = command & FTRACE_UPDATE_TRACE_FUNC; int mod_flags = 0; int err = 0; + union ftrace_func func; if (command & FTRACE_MAY_SLEEP) mod_flags = FTRACE_MODIFY_MAY_SLEEP_FL; @@ -2695,7 +2703,8 @@ void ftrace_modify_all_code(int command) * traced. */ if (update) { - err = ftrace_update_ftrace_func(ftrace_ops_list_func); + ftrace_set_ufunc(&func, ftrace_ops_list_func); + err = ftrace_update_ftrace_func(func.ops); if (FTRACE_WARN_ON(err)) return; } @@ -2705,7 +2714,9 @@ void ftrace_modify_all_code(int command) else if (command & FTRACE_DISABLE_CALLS) ftrace_replace_code(mod_flags); - if (update && ftrace_trace_function != ftrace_ops_list_func) { + ftrace_set_ufunc(&func, ftrace_ops_list_func); + + if (update && ftrace_trace_function != func.ops) { function_trace_op = set_function_trace_op; smp_wmb(); /* If irqs are disabled, we are in stop machine */ @@ -6890,14 +6901,13 @@ static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip, { __ftrace_ops_list_func(ip, parent_ip, NULL, regs); } -NOKPROBE_SYMBOL(ftrace_ops_list_func); #else -static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip) +static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip) { __ftrace_ops_list_func(ip, parent_ip, NULL, NULL); } -NOKPROBE_SYMBOL(ftrace_ops_no_ops); #endif +NOKPROBE_SYMBOL(ftrace_ops_list_func); /* * If there's only one function registered but it does not support