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X-Microsoft-Antispam-Message-Info: J3SFLmv6NPbHx6iETxxurtJdY/Nx1cNWxBqQruEpUuSP1fHQLEPNgcnp8ZyM4zgQMtPPB+hyKgP8YXqwCMVQ4KHwQ8f2L7jHSD8Oa3qijvs00ModJW21r+UT8mdphD0NT8oSJo/ZdwSCQ5mmrbCgQircaR5Us2icVKqL+umDced73HGAgNIShznzzQhQ5DX/pJuTdO63YBZzeQ0XdmjNZjHJ/h8V+5bLHSjVyprv4KCdBYAaXaZH2Spx/69/Tzeu4Y6NYjWPUw1ro+bZgqCursMmvQ7La9v3emNClNg4FOY2YqUauLO6oH+SMo4tAUGrwfI607ieZM01xZQ4xp4t0L5F7Z/q7s6irUBHo3Zpyfs1UDXpwsoOd/mafqKxZ/cj9Xhm7n1CcuiT3uQumpH6mb5tqfq0/aCd4irANK0RjDkF7jKhLw4nMWDy8icEj9fM X-MS-Exchange-AntiSpam-MessageData: +GeGbF2ZuZrzqo0oOO6RsSIrI2EZDcJVQGp/TCgWAlst1701OrDhq+Cplrq+fnTN9XWPCqQGBn8rkMCcDrbkrTkzNjpPZ1xClklny+lEbd428JQ8wWd6U/VMhHQEiZttm5AJHLDUnsbGq7LoZbu60Q== X-OriginatorOrg: nokia.com X-MS-Exchange-CrossTenant-Network-Message-Id: bc84eef7-e7aa-4167-ef83-08d7b3b34715 X-MS-Exchange-CrossTenant-OriginalArrivalTime: 17 Feb 2020 14:11:27.0551 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 5d471751-9675-428d-917b-70f44f9630b0 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: gzQ3U1e2tBEdvOowLxvPtgVyNzyUakbzkhSOijZoUUwIXXEHnzrWr4/ko2xfoMpGgXHrOTIlEc08R5qgOBeEDnnVt/WX0y1lmPxnh0hdW48= X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR07MB5056 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200217_061134_340676_C9DF8D4F X-CRM114-Status: GOOD ( 15.71 ) X-Spam-Score: 3.6 (+++) X-Spam-Report: SpamAssassin version 3.4.3 on bombadil.infradead.org summary: Content analysis details: (3.6 points) pts rule name description ---- ---------------------- -------------------------------------------------- 3.6 RCVD_IN_SBL_CSS RBL: Received via a relay in Spamhaus SBL-CSS [131.228.32.181 listed in zen.spamhaus.org] -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [40.107.20.98 listed in list.dnswl.org] -0.0 SPF_HELO_PASS SPF: HELO matches SPF record -0.0 SPF_PASS SPF: sender matches SPF record 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 0.0 MSGID_FROM_MTA_HEADER Message-Id was added by a relay -0.0 DKIMWL_WL_HIGH DKIMwl.org - Whitelisted High sender X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Ard Biesheuvel , linux-kernel@vger.kernel.org, Steven Rostedt , Russell King , Ingo Molnar , Alexander Sverdlin Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org From: Alexander Sverdlin 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/ftrace.h | 3 +++ arch/arm/include/asm/module.h | 1 + arch/arm/kernel/ftrace.c | 46 +++++++++++++++++++++++++++++++++++++++++-- arch/arm/kernel/module-plts.c | 44 +++++++++++++++++++++++++++++++++++++---- 4 files changed, 88 insertions(+), 6 deletions(-) diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h index 48ec1d0..a4dbac0 100644 --- a/arch/arm/include/asm/ftrace.h +++ b/arch/arm/include/asm/ftrace.h @@ -15,6 +15,9 @@ extern void __gnu_mcount_nc(void); #ifdef CONFIG_DYNAMIC_FTRACE struct dyn_arch_ftrace { +#ifdef CONFIG_ARM_MODULE_PLTS + struct module *mod; +#endif }; static inline unsigned long ftrace_call_adjust(unsigned long addr) diff --git a/arch/arm/include/asm/module.h b/arch/arm/include/asm/module.h index 78e4c16..961fedb 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 10499d4..75830e5 100644 --- a/arch/arm/kernel/ftrace.c +++ b/arch/arm/kernel/ftrace.c @@ -70,6 +70,19 @@ 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); } @@ -123,10 +136,22 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) { 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) { + struct module *mod = rec->arch.mod; + + 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); } @@ -151,12 +176,29 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, 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); + +#ifdef CONFIG_ARM_MODULE_PLTS + if (!old && mod) { + aaddr = get_module_plt(mod, ip, aaddr); + old = ftrace_call_replace(ip, aaddr); + } +#endif + new = ftrace_nop_replace(rec); ret = ftrace_modify_code(ip, old, new, true); diff --git a/arch/arm/kernel/module-plts.c b/arch/arm/kernel/module-plts.c index d330e9e..a0524ad 100644 --- a/arch/arm/kernel/module-plts.c +++ b/arch/arm/kernel/module-plts.c @@ -4,6 +4,7 @@ */ #include +#include #include #include #include @@ -20,19 +21,52 @@ (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. @@ -180,8 +214,8 @@ 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; @@ -236,6 +270,7 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, 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; @@ -243,6 +278,7 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, 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);