From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from EUR02-AM5-obe.outbound.protection.outlook.com (mail-eopbgr00128.outbound.protection.outlook.com [40.107.0.128]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3znyC65p4zzF1lF for ; Sat, 24 Feb 2018 04:00:18 +1100 (AEDT) From: Alexander Sverdlin To: Steven Rostedt , Ingo Molnar , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Alexander Sverdlin , Russell King , Catalin Marinas , Will Deacon , Steven Miao , Tony Luck , Fenghua Yu , James Hogan , Michal Simek , Ralf Baechle , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Martin Schwidefsky , Heiko Carstens , Yoshinori Sato , Rich Felker , "David S. Miller" , Chris Metcalf , Thomas Gleixner , "H. Peter Anvin" , x86@kernel.org, adi-buildroot-devel@lists.sourceforge.net, linux-ia64@vger.kernel.org, linux-metag@vger.kernel.org, linux-mips@linux-mips.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org Subject: [PATCH 3/3] ftrace: Add MODULE_PLTS support Date: Fri, 23 Feb 2018 17:58:49 +0100 Message-Id: <20180223165849.16388-4-alexander.sverdlin@nokia.com> In-Reply-To: <20180223165849.16388-1-alexander.sverdlin@nokia.com> References: <20180223165849.16388-1-alexander.sverdlin@nokia.com> MIME-Version: 1.0 Content-Type: text/plain List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 --- arch/arm/include/asm/module.h | 1 + arch/arm/kernel/ftrace.c | 70 ++++++++++++++++++++++++++++++++++++------- arch/arm/kernel/module-plts.c | 53 ++++++++++++++++++++++++-------- 3 files changed, 101 insertions(+), 23 deletions(-) diff --git a/arch/arm/include/asm/module.h b/arch/arm/include/asm/module.h index 6996405..e3d7a51 100644 --- a/arch/arm/include/asm/module.h +++ b/arch/arm/include/asm/module.h @@ -30,6 +30,7 @@ struct plt_entries { struct mod_plt_sec { struct elf32_shdr *plt; + struct plt_entries *plt_ent; int plt_count; }; diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c index be20adc..0a0da25 100644 --- a/arch/arm/kernel/ftrace.c +++ b/arch/arm/kernel/ftrace.c @@ -98,6 +98,19 @@ int ftrace_arch_code_modify_post_process(void) static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr) { + s32 offset = addr - pc; + s32 blim = 0xfe000008; + s32 flim = 0x02000004; + + if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) { + blim = 0xff000004; + flim = 0x01000002; + } + + if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS) && + (offset < blim || offset > flim)) + return 0; + return arm_gen_branch_link(pc, addr); } @@ -167,10 +180,27 @@ int ftrace_make_call(struct module *mod, struct dyn_ftrace *rec, { unsigned long new, old; unsigned long ip = rec->ip; + unsigned long aaddr = adjust_address(rec, addr); old = ftrace_nop_replace(rec); - new = ftrace_call_replace(ip, adjust_address(rec, addr)); + new = ftrace_call_replace(ip, aaddr); + +#ifdef CONFIG_ARM_MODULE_PLTS + if (!new) { + /* + * mod is only supplied during module loading, later we have to + * search for it + */ + if (!mod) + mod = __module_address(ip); + + if (mod) { + aaddr = get_module_plt(mod, ip, aaddr); + new = ftrace_call_replace(ip, aaddr); + } + } +#endif return ftrace_modify_code(rec->ip, old, new, true); } @@ -200,20 +230,40 @@ int ftrace_make_nop(struct module *mod, unsigned long new; int ret; - old = ftrace_call_replace(ip, adjust_address(rec, addr)); - new = ftrace_nop_replace(rec); - ret = ftrace_modify_code(ip, old, new, true); - -#ifdef CONFIG_OLD_MCOUNT - if (ret == -EINVAL && addr == MCOUNT_ADDR) { - rec->arch.old_mcount = true; + for (;;) { + unsigned long aaddr = adjust_address(rec, addr); + + old = ftrace_call_replace(ip, aaddr); + +#ifdef CONFIG_ARM_MODULE_PLTS + if (!old) { + /* + * mod is only supplied during module loading, later we + * have to search for it + */ + if (!mod) + mod = __module_address(ip); + + if (mod) { + aaddr = get_module_plt(mod, ip, aaddr); + old = ftrace_call_replace(ip, aaddr); + } + } +#endif - old = ftrace_call_replace(ip, adjust_address(rec, addr)); new = ftrace_nop_replace(rec); ret = ftrace_modify_code(ip, old, new, true); - } + +#ifdef CONFIG_OLD_MCOUNT + if (ret == -EINVAL && !rec->arch.old_mcount) { + rec->arch.old_mcount = true; + continue; + } #endif + break; + } + return ret; } diff --git a/arch/arm/kernel/module-plts.c b/arch/arm/kernel/module-plts.c index f272711..a216256 100644 --- a/arch/arm/kernel/module-plts.c +++ b/arch/arm/kernel/module-plts.c @@ -7,6 +7,7 @@ */ #include +#include #include #include #include @@ -22,6 +23,15 @@ (PLT_ENT_STRIDE - 8)) #endif +static u32 fixed_plts[] = { + FTRACE_ADDR, + MCOUNT_ADDR, +#ifdef CONFIG_OLD_MCOUNT + (unsigned long)ftrace_caller_old, + (unsigned long)mcount, +#endif +}; + static bool in_init(const struct module *mod, unsigned long loc) { return loc - (u32)mod->init_layout.base < mod->init_layout.size; @@ -31,26 +41,43 @@ 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; + int idx; + struct plt_entries *plt; + + /* Pre-allocate entries in the first plt */ + if (!pltsec->plt_count) { + plt = (struct plt_entries *)pltsec->plt->sh_addr; + for (idx = 0; idx < ARRAY_SIZE(plt->ldr); ++idx) + plt->ldr[idx] = PLT_ENT_LDR; + memcpy(plt->lit, fixed_plts, sizeof(fixed_plts)); + pltsec->plt_count = ARRAY_SIZE(fixed_plts); + /* + * cache the address, + * ELF header is available only during module load + */ + pltsec->plt_ent = plt; + } + plt = pltsec->plt_ent; - struct plt_entries *plt = (struct plt_entries *)pltsec->plt->sh_addr; - int idx = 0; + idx = ARRAY_SIZE(fixed_plts); + while (idx) + if (plt->lit[--idx] == val) + return (u32)&plt->ldr[idx]; /* * Look for an existing entry pointing to 'val'. Given that the * relocations are sorted, this will be the last entry we allocated. * (if one exists). */ - if (pltsec->plt_count > 0) { - plt += (pltsec->plt_count - 1) / PLT_ENT_COUNT; - idx = (pltsec->plt_count - 1) % PLT_ENT_COUNT; + plt += (pltsec->plt_count - 1) / PLT_ENT_COUNT; + idx = (pltsec->plt_count - 1) % PLT_ENT_COUNT; - if (plt->lit[idx] == val) - return (u32)&plt->ldr[idx]; + if (plt->lit[idx] == val) + return (u32)&plt->ldr[idx]; - idx = (idx + 1) % PLT_ENT_COUNT; - if (!idx) - plt++; - } + idx = (idx + 1) % PLT_ENT_COUNT; + if (!idx) + plt++; pltsec->plt_count++; BUG_ON(pltsec->plt_count * PLT_ENT_SIZE > pltsec->plt->sh_size); @@ -182,8 +209,8 @@ static unsigned int count_plts(const Elf32_Sym *syms, Elf32_Addr base, 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; -- 2.4.6