From patchwork Wed Jun 7 16:55:26 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Naveen N Rao X-Patchwork-Id: 1791838 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org (client-ip=2404:9400:2:0:216:3eff:fee1:b9f1; helo=lists.ozlabs.org; envelope-from=linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org; receiver=) Authentication-Results: legolas.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=nQgX/P16; dkim-atps=neutral Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2404:9400:2:0:216:3eff:fee1:b9f1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-384) server-digest SHA384) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4QbtsP115xz20Q8 for ; Thu, 8 Jun 2023 03:01:13 +1000 (AEST) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4QbtsP07Tjz3dtF for ; Thu, 8 Jun 2023 03:01:13 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=nQgX/P16; dkim-atps=neutral X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=2604:1380:4641:c500::1; helo=dfw.source.kernel.org; envelope-from=naveen@kernel.org; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=nQgX/P16; dkim-atps=neutral Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4Qbtr44Wg0z3dtM for ; Thu, 8 Jun 2023 03:00:04 +1000 (AEST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id A8CE964017; Wed, 7 Jun 2023 17:00:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 975ECC433D2; Wed, 7 Jun 2023 16:59:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1686157199; bh=elimukr1tAjj5cZi3vE0CMCZ4dYVSpWrsdSSpurSXXw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nQgX/P16vhzJFYo4YXrCOCGM81YTv9FbQzUZpR8ie/NIYqMhIENWLeRyhnSwey9+O sdoiJq7dGcN6JheDcav+eAbx9qq+pAdMUML6v64jmLhtJsBhC+U/9GnyjMbLMG1kfU jegZGvam8F7jCa5U4H82KmjQ5BdsANd2zRLqLUtArapjP/ziWKf6Hk8UqFtQQDq3UI a7DsLaJEEZDnKnwi9XslZaIVPiTNveFVx28hUpoDNlnI8FVQiJ246QSg1IF035iQ2U /K7uZb5a7xn1ZGFe899pa0eCFVJIaHq6uUoDKXzM/VqDkU6zO/Ak+9qsKVA+WGr2np ZWH8+jMPuGsFw== From: Naveen N Rao To: Subject: [RFC PATCH 11/15] powerpc/ftrace: Simplify ftrace_make_call() Date: Wed, 7 Jun 2023 22:25:26 +0530 Message-Id: <401740584309ef3498a166e01dd928546df2133f.1686151854.git.naveen@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: References: MIME-Version: 1.0 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Steven Rostedt , Nicholas Piggin Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" Now that we validate the ftrace location during initialization in ftrace_init_nop(), we can simplify ftrace_make_call() to replace the nop without worrying about the instructions surrounding the ftrace location. Note that we continue to ensure that we have a nop at the ftrace location before patching it. Signed-off-by: Naveen N Rao --- arch/powerpc/kernel/trace/ftrace.c | 187 +++++------------------------ 1 file changed, 31 insertions(+), 156 deletions(-) diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c index 67773cd14da71a..8d5d91b8ae85a0 100644 --- a/arch/powerpc/kernel/trace/ftrace.c +++ b/arch/powerpc/kernel/trace/ftrace.c @@ -129,162 +129,6 @@ static unsigned long find_ftrace_tramp(unsigned long ip) return 0; } -#ifdef CONFIG_MODULES -/* - * Examine the existing instructions for __ftrace_make_call. - * They should effectively be a NOP, and follow formal constraints, - * depending on the ABI. Return false if they don't. - */ -static bool expected_nop_sequence(void *ip, ppc_inst_t op0, ppc_inst_t op1) -{ - if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS)) - return ppc_inst_equal(op0, ppc_inst(PPC_RAW_NOP())); - else - return ppc_inst_equal(op0, ppc_inst(PPC_RAW_BRANCH(8))) && - ppc_inst_equal(op1, ppc_inst(PPC_INST_LD_TOC)); -} - -static int -__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) -{ - ppc_inst_t op[2]; - void *ip = (void *)rec->ip; - unsigned long entry, ptr, tramp; - struct module *mod = rec->arch.mod; - - /* read where this goes */ - if (copy_inst_from_kernel_nofault(op, ip)) - return -EFAULT; - - if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && - copy_inst_from_kernel_nofault(op + 1, ip + 4)) - return -EFAULT; - - if (!expected_nop_sequence(ip, op[0], op[1])) { - pr_err("Unexpected call sequence at %p: %08lx %08lx\n", ip, - ppc_inst_as_ulong(op[0]), ppc_inst_as_ulong(op[1])); - return -EINVAL; - } - - /* If we never set up ftrace trampoline(s), then bail */ - if (!mod->arch.tramp || - (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !mod->arch.tramp_regs)) { - pr_err("No ftrace trampoline\n"); - return -EINVAL; - } - - if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && rec->flags & FTRACE_FL_REGS) - tramp = mod->arch.tramp_regs; - else - tramp = mod->arch.tramp; - - if (module_trampoline_target(mod, tramp, &ptr)) { - pr_err("Failed to get trampoline target\n"); - return -EFAULT; - } - - pr_devel("trampoline target %lx", ptr); - - entry = ppc_global_function_entry((void *)addr); - /* This should match what was called */ - if (ptr != entry) { - pr_err("addr %lx does not match expected %lx\n", ptr, entry); - return -EINVAL; - } - - if (patch_branch(ip, tramp, BRANCH_SET_LINK)) { - pr_err("REL24 out of range!\n"); - return -EINVAL; - } - - return 0; -} -#else -static int __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) -{ - return 0; -} -#endif /* CONFIG_MODULES */ - -static int __ftrace_make_call_kernel(struct dyn_ftrace *rec, unsigned long addr) -{ - ppc_inst_t op; - void *ip = (void *)rec->ip; - unsigned long tramp, entry, ptr; - - /* Make sure we're being asked to patch branch to a known ftrace addr */ - entry = ppc_global_function_entry((void *)ftrace_caller); - ptr = ppc_global_function_entry((void *)addr); - - if (ptr != entry && IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS)) - entry = ppc_global_function_entry((void *)ftrace_regs_caller); - - if (ptr != entry) { - pr_err("Unknown ftrace addr to patch: %ps\n", (void *)ptr); - return -EINVAL; - } - - /* Make sure we have a nop */ - if (copy_inst_from_kernel_nofault(&op, ip)) { - pr_err("Unable to read ftrace location %p\n", ip); - return -EFAULT; - } - - if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_NOP()))) { - pr_err("Unexpected call sequence at %p: %08lx\n", - ip, ppc_inst_as_ulong(op)); - return -EINVAL; - } - - tramp = find_ftrace_tramp((unsigned long)ip); - if (!tramp) { - pr_err("No ftrace trampolines reachable from %ps\n", ip); - return -EINVAL; - } - - if (patch_branch(ip, tramp, BRANCH_SET_LINK)) { - pr_err("Error patching branch to ftrace tramp!\n"); - return -EINVAL; - } - - return 0; -} - -int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) -{ - unsigned long ip = rec->ip; - ppc_inst_t old, new; - - /* - * If the calling address is more that 24 bits away, - * then we had to use a trampoline to make the call. - * Otherwise just update the call site. - */ - if (test_24bit_addr(ip, addr)) { - /* within range */ - old = ppc_inst(PPC_RAW_NOP()); - new = ftrace_call_replace(ip, addr, 1); - return ftrace_modify_code(ip, old, new); - } else if (core_kernel_text(ip)) { - return __ftrace_make_call_kernel(rec, addr); - } else if (!IS_ENABLED(CONFIG_MODULES)) { - /* We should not get here without modules */ - return -EINVAL; - } - - /* - * Out of range jumps are called from modules. - * Being that we are converting from nop, it had better - * already have a module defined. - */ - if (!rec->arch.mod) { - pr_err("No module loaded\n"); - return -EINVAL; - } - - return __ftrace_make_call(rec, addr); -} - #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS #ifdef CONFIG_MODULES static int @@ -419,6 +263,37 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, } #endif +int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) +{ + unsigned long tramp, ip = rec->ip; + ppc_inst_t old, new; + struct module *mod; + + old = ppc_inst(PPC_RAW_NOP()); + if (is_offset_in_branch_range(addr - ip)) { + /* Within range */ + new = ftrace_create_branch_inst(ip, addr, 1); + return ftrace_modify_code(ip, old, new); + } else if (core_kernel_text(ip)) { + /* We would be branching to one of our ftrace tramps */ + tramp = find_ftrace_tramp(ip); + if (!tramp) { + pr_err("0x%lx: No ftrace trampolines reachable\n", ip); + return -EINVAL; + } + new = ftrace_create_branch_inst(ip, tramp, 1); + return ftrace_modify_code(ip, old, new); + } else if (IS_ENABLED(CONFIG_MODULES)) { + /* Module code would be going to one of the module stubs */ + mod = rec->arch.mod; + tramp = (addr == (unsigned long)ftrace_caller ? mod->arch.tramp : mod->arch.tramp_regs); + new = ftrace_create_branch_inst(ip, tramp, 1); + return ftrace_modify_code(ip, old, new); + } + + return -EINVAL; +} + int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) { unsigned long tramp, ip = rec->ip;