From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 718D2C433F5 for ; Mon, 4 Oct 2021 13:00:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 59C7C61B44 for ; Mon, 4 Oct 2021 13:00:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233891AbhJDNCc (ORCPT ); Mon, 4 Oct 2021 09:02:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:60646 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233638AbhJDNBB (ORCPT ); Mon, 4 Oct 2021 09:01:01 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6654761373; Mon, 4 Oct 2021 12:58:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1633352297; bh=nRMFoo3HxI4phZvJtWxIoMmTmeWDnMZOzkC1N3o7H+g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EX0U0JZ/5GL75bCcXs4XVsglbXxqwtmDax1/rEc/bXgfoTjgbD16QBuiO488D8r98 LItZcb8PecXEY7eELf8xLsCyX8fPWHhcipIXBVf35ph7G9zdtSsvsIglCX5xpIX+sC EkDO+mj/OxsLsyuMuWEKi1WLpt4VSpHKmagqEP68= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexander Sverdlin , Russell King , Florian Fainelli Subject: [PATCH 4.9 51/57] ARM: 9079/1: ftrace: Add MODULE_PLTS support Date: Mon, 4 Oct 2021 14:52:35 +0200 Message-Id: <20211004125030.562670629@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20211004125028.940212411@linuxfoundation.org> References: <20211004125028.940212411@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Alex Sverdlin commit 79f32b221b18c15a98507b101ef4beb52444cc6f upstream Teach ftrace_make_call() and ftrace_make_nop() about PLTs. Teach PLT code about FTRACE and all its callbacks. Otherwise the following might happen: ------------[ cut here ]------------ WARNING: CPU: 14 PID: 2265 at .../arch/arm/kernel/insn.c:14 __arm_gen_branch+0x83/0x8c() ... Hardware name: LSI Axxia AXM55XX [] (unwind_backtrace) from [] (show_stack+0x11/0x14) [] (show_stack) from [] (dump_stack+0x81/0xa8) [] (dump_stack) from [] (warn_slowpath_common+0x69/0x90) [] (warn_slowpath_common) from [] (warn_slowpath_null+0x17/0x1c) [] (warn_slowpath_null) from [] (__arm_gen_branch+0x83/0x8c) [] (__arm_gen_branch) from [] (ftrace_make_nop+0xf/0x24) [] (ftrace_make_nop) from [] (ftrace_process_locs+0x27b/0x3e8) [] (ftrace_process_locs) from [] (load_module+0x11e9/0x1a44) [] (load_module) from [] (SyS_finit_module+0x59/0x84) [] (SyS_finit_module) from [] (ret_fast_syscall+0x1/0x18) ---[ end trace e1b64ced7a89adcc ]--- ------------[ cut here ]------------ WARNING: CPU: 14 PID: 2265 at .../kernel/trace/ftrace.c:1979 ftrace_bug+0x1b1/0x234() ... Hardware name: LSI Axxia AXM55XX [] (unwind_backtrace) from [] (show_stack+0x11/0x14) [] (show_stack) from [] (dump_stack+0x81/0xa8) [] (dump_stack) from [] (warn_slowpath_common+0x69/0x90) [] (warn_slowpath_common) from [] (warn_slowpath_null+0x17/0x1c) [] (warn_slowpath_null) from [] (ftrace_bug+0x1b1/0x234) [] (ftrace_bug) from [] (ftrace_process_locs+0x285/0x3e8) [] (ftrace_process_locs) from [] (load_module+0x11e9/0x1a44) [] (load_module) from [] (SyS_finit_module+0x59/0x84) [] (SyS_finit_module) from [] (ret_fast_syscall+0x1/0x18) ---[ end trace e1b64ced7a89adcd ]--- ftrace failed to modify [] 0xe9ef7006 actual: 02:f0:3b:fa ftrace record flags: 0 (0) expected tramp: c0314265 Signed-off-by: Alexander Sverdlin Signed-off-by: Russell King Signed-off-by: Florian Fainelli Signed-off-by: Greg Kroah-Hartman --- arch/arm/include/asm/ftrace.h | 3 ++ arch/arm/include/asm/module.h | 1 arch/arm/kernel/ftrace.c | 45 +++++++++++++++++++++++++++++++++++------- arch/arm/kernel/module-plts.c | 44 +++++++++++++++++++++++++++++++++++++---- 4 files changed, 82 insertions(+), 11 deletions(-) --- a/arch/arm/include/asm/ftrace.h +++ b/arch/arm/include/asm/ftrace.h @@ -14,6 +14,9 @@ struct dyn_arch_ftrace { #ifdef CONFIG_OLD_MCOUNT bool old_mcount; #endif +#ifdef CONFIG_ARM_MODULE_PLTS + struct module *mod; +#endif }; static inline unsigned long ftrace_call_adjust(unsigned long addr) --- a/arch/arm/include/asm/module.h +++ b/arch/arm/include/asm/module.h @@ -29,6 +29,7 @@ struct plt_entries { struct mod_plt_sec { struct elf32_shdr *plt; + struct plt_entries *plt_ent; int plt_count; }; --- a/arch/arm/kernel/ftrace.c +++ b/arch/arm/kernel/ftrace.c @@ -95,9 +95,10 @@ int ftrace_arch_code_modify_post_process return 0; } -static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr) +static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr, + bool warn) { - return arm_gen_branch_link(pc, addr, true); + return arm_gen_branch_link(pc, addr, warn); } static int ftrace_modify_code(unsigned long pc, unsigned long old, @@ -136,14 +137,14 @@ int ftrace_update_ftrace_func(ftrace_fun int ret; pc = (unsigned long)&ftrace_call; - new = ftrace_call_replace(pc, (unsigned long)func); + new = ftrace_call_replace(pc, (unsigned long)func, true); ret = ftrace_modify_code(pc, 0, new, false); #ifdef CONFIG_OLD_MCOUNT if (!ret) { pc = (unsigned long)&ftrace_call_old; - new = ftrace_call_replace(pc, (unsigned long)func); + new = ftrace_call_replace(pc, (unsigned long)func, true); ret = ftrace_modify_code(pc, 0, new, false); } @@ -156,9 +157,21 @@ int ftrace_make_call(struct dyn_ftrace * { unsigned long new, old; unsigned long ip = rec->ip; + unsigned long aaddr = adjust_address(rec, addr); + struct module *mod = NULL; + +#ifdef CONFIG_ARM_MODULE_PLTS + mod = rec->arch.mod; +#endif old = ftrace_nop_replace(rec); - new = ftrace_call_replace(ip, adjust_address(rec, addr)); + new = ftrace_call_replace(ip, aaddr, !mod); +#ifdef CONFIG_ARM_MODULE_PLTS + if (!new && mod) { + aaddr = get_module_plt(mod, ip, aaddr); + new = ftrace_call_replace(ip, aaddr, true); + } +#endif return ftrace_modify_code(rec->ip, old, new, true); } @@ -166,12 +179,29 @@ int ftrace_make_call(struct dyn_ftrace * int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) { + unsigned long aaddr = adjust_address(rec, addr); unsigned long ip = rec->ip; unsigned long old; unsigned long new; int ret; - old = ftrace_call_replace(ip, adjust_address(rec, addr)); +#ifdef CONFIG_ARM_MODULE_PLTS + /* mod is only supplied during module loading */ + if (!mod) + mod = rec->arch.mod; + else + rec->arch.mod = mod; +#endif + + old = ftrace_call_replace(ip, aaddr, + !IS_ENABLED(CONFIG_ARM_MODULE_PLTS) || !mod); +#ifdef CONFIG_ARM_MODULE_PLTS + if (!old && mod) { + aaddr = get_module_plt(mod, ip, aaddr); + old = ftrace_call_replace(ip, aaddr, true); + } +#endif + new = ftrace_nop_replace(rec); ret = ftrace_modify_code(ip, old, new, true); @@ -179,7 +209,8 @@ int ftrace_make_nop(struct module *mod, if (ret == -EINVAL && addr == MCOUNT_ADDR) { rec->arch.old_mcount = true; - old = ftrace_call_replace(ip, adjust_address(rec, addr)); + old = ftrace_call_replace(ip, adjust_address(rec, addr), + !IS_ENABLED(CONFIG_ARM_MODULE_PLTS) || !mod); new = ftrace_nop_replace(rec); ret = ftrace_modify_code(ip, old, new, true); } --- a/arch/arm/kernel/module-plts.c +++ b/arch/arm/kernel/module-plts.c @@ -7,6 +7,7 @@ */ #include +#include #include #include #include @@ -22,19 +23,52 @@ (PLT_ENT_STRIDE - 8)) #endif +static const u32 fixed_plts[] = { +#ifdef CONFIG_FUNCTION_TRACER + FTRACE_ADDR, + MCOUNT_ADDR, +#endif +}; + static bool in_init(const struct module *mod, unsigned long loc) { return loc - (u32)mod->init_layout.base < mod->init_layout.size; } +static void prealloc_fixed(struct mod_plt_sec *pltsec, struct plt_entries *plt) +{ + int i; + + if (!ARRAY_SIZE(fixed_plts) || pltsec->plt_count) + return; + pltsec->plt_count = ARRAY_SIZE(fixed_plts); + + for (i = 0; i < ARRAY_SIZE(plt->ldr); ++i) + plt->ldr[i] = PLT_ENT_LDR; + + BUILD_BUG_ON(sizeof(fixed_plts) > sizeof(plt->lit)); + memcpy(plt->lit, fixed_plts, sizeof(fixed_plts)); +} + u32 get_module_plt(struct module *mod, unsigned long loc, Elf32_Addr val) { struct mod_plt_sec *pltsec = !in_init(mod, loc) ? &mod->arch.core : &mod->arch.init; + struct plt_entries *plt; + int idx; + + /* cache the address, ELF header is available only during module load */ + if (!pltsec->plt_ent) + pltsec->plt_ent = (struct plt_entries *)pltsec->plt->sh_addr; + plt = pltsec->plt_ent; - struct plt_entries *plt = (struct plt_entries *)pltsec->plt->sh_addr; - int idx = 0; + prealloc_fixed(pltsec, plt); + + for (idx = 0; idx < ARRAY_SIZE(fixed_plts); ++idx) + if (plt->lit[idx] == val) + return (u32)&plt->ldr[idx]; + idx = 0; /* * Look for an existing entry pointing to 'val'. Given that the * relocations are sorted, this will be the last entry we allocated. @@ -182,8 +216,8 @@ static unsigned int count_plts(const Elf int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, char *secstrings, struct module *mod) { - unsigned long core_plts = 0; - unsigned long init_plts = 0; + unsigned long core_plts = ARRAY_SIZE(fixed_plts); + unsigned long init_plts = ARRAY_SIZE(fixed_plts); Elf32_Shdr *s, *sechdrs_end = sechdrs + ehdr->e_shnum; Elf32_Sym *syms = NULL; @@ -238,6 +272,7 @@ int module_frob_arch_sections(Elf_Ehdr * mod->arch.core.plt->sh_size = round_up(core_plts * PLT_ENT_SIZE, sizeof(struct plt_entries)); mod->arch.core.plt_count = 0; + mod->arch.core.plt_ent = NULL; mod->arch.init.plt->sh_type = SHT_NOBITS; mod->arch.init.plt->sh_flags = SHF_EXECINSTR | SHF_ALLOC; @@ -245,6 +280,7 @@ int module_frob_arch_sections(Elf_Ehdr * mod->arch.init.plt->sh_size = round_up(init_plts * PLT_ENT_SIZE, sizeof(struct plt_entries)); mod->arch.init.plt_count = 0; + mod->arch.init.plt_ent = NULL; pr_debug("%s: plt=%x, init.plt=%x\n", __func__, mod->arch.core.plt->sh_size, mod->arch.init.plt->sh_size);