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[209.132.180.67]) by mx.google.com with ESMTP id c17si1975163pfb.81.2018.12.13.09.33.30; Thu, 13 Dec 2018 09:33:46 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729631AbeLMRbw (ORCPT + 99 others); Thu, 13 Dec 2018 12:31:52 -0500 Received: from foss.arm.com ([217.140.101.70]:39198 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727579AbeLMRbw (ORCPT ); Thu, 13 Dec 2018 12:31:52 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 3CDC61688; Thu, 13 Dec 2018 09:31:51 -0800 (PST) Received: from mail-it1-f169.google.com (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 161CF3FA42; Thu, 13 Dec 2018 09:31:51 -0800 (PST) Received: by mail-it1-f169.google.com with SMTP id o19so4840030itg.5; Thu, 13 Dec 2018 09:31:51 -0800 (PST) X-Gm-Message-State: AA+aEWZHMusabCexaG+c6Uso7XAY1EYGXZs5ZZPLxCH7tt2KGsz4clSs Eb2IiuY7wgHy/YhTgQ1Xi1Tmc6U3p9OoqFTwhvE= X-Received: by 2002:a02:6915:: with SMTP id e21mr24235701jac.142.1544722310115; Thu, 13 Dec 2018 09:31:50 -0800 (PST) MIME-Version: 1.0 References: <20181130162015.83FE767357@newverein.lst.de> In-Reply-To: <20181130162015.83FE767357@newverein.lst.de> From: Amit Daniel Kachhap Date: Thu, 13 Dec 2018 23:01:38 +0530 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v5] arm64: implement ftrace with regs To: duwe@lst.de Cc: Will Deacon , Catalin Marinas , julien.thierry@arm.com, rostedt@goodmis.org, jpoimboe@redhat.com, mingo@redhat.com, Ard Biesheuvel , Arnd Bergmann , takahiro.akashi@linaro.org, LAK , linux-kernel@vger.kernel.org, live-patching@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 30, 2018 at 9:53 PM Torsten Duwe wrote: > > Use -fpatchable-function-entry (gcc8) to add 2 NOPs at the beginning > of each function. Replace the first NOP thus generated with a quick LR > saver (move it to scratch reg x9), so the 2nd replacement insn, the call > to ftrace, does not clobber the value. Ftrace will then generate the > standard stack frames. > > Note that patchable-function-entry in GCC disables IPA-RA, which means > ABI register calling conventions are obeyed *and* scratch registers > such as x9 are available. > > Introduce and handle an ftrace_regs_trampoline for module PLTs, together > with ftrace_trampoline, and double the size of this special section > if .text.ftrace_trampoline is present in the module. Hi Torsten, I was testing your patch and it seems to work fine for function trace. However function graph trace seems broken. Is it work in progress ? or I am missing something. Regards, Amit Daniel > > Signed-off-by: Torsten Duwe > > --- > > As reliable stack traces are still being discussed, here is > dynamic ftrace with regs only, which has a value of its own. > I can see Mark has broken down an earlier version into smaller > patches; just let me know if you prefer that. > > [Changes from v4] > > * include Ard's feedback and pending changes: > - ADR/ADRP veneers > - ftrace_trampolines[2] > - add a .req for fp, just in case > - comment on the pt_regs.stackframe[2] mapping > * include Mark's ftrace cleanup > - GLOBAL() > - prepare_ftrace_return(pc, &lr, fp) > > --- > arch/arm64/Kconfig | 2 > arch/arm64/Makefile | 4 + > arch/arm64/include/asm/assembler.h | 1 > arch/arm64/include/asm/ftrace.h | 13 +++ > arch/arm64/include/asm/module.h | 3 > arch/arm64/kernel/Makefile | 6 - > arch/arm64/kernel/entry-ftrace.S | 130 ++++++++++++++++++++++++++++++++++ > arch/arm64/kernel/ftrace.c | 125 +++++++++++++++++++++++++------- > arch/arm64/kernel/module-plts.c | 3 > arch/arm64/kernel/module.c | 2 > drivers/firmware/efi/libstub/Makefile | 3 > include/asm-generic/vmlinux.lds.h | 1 > include/linux/compiler_types.h | 4 + > 13 files changed, 261 insertions(+), 36 deletions(-) > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -125,6 +125,8 @@ config ARM64 > select HAVE_DEBUG_KMEMLEAK > select HAVE_DMA_CONTIGUOUS > select HAVE_DYNAMIC_FTRACE > + select HAVE_DYNAMIC_FTRACE_WITH_REGS \ > + if $(cc-option,-fpatchable-function-entry=2) > select HAVE_EFFICIENT_UNALIGNED_ACCESS > select HAVE_FTRACE_MCOUNT_RECORD > select HAVE_FUNCTION_TRACER > --- a/arch/arm64/Makefile > +++ b/arch/arm64/Makefile > @@ -79,6 +79,10 @@ ifeq ($(CONFIG_ARM64_MODULE_PLTS),y) > KBUILD_LDFLAGS_MODULE += -T $(srctree)/arch/arm64/kernel/module.lds > endif > > +ifeq ($(CONFIG_DYNAMIC_FTRACE_WITH_REGS),y) > + CC_FLAGS_FTRACE := -fpatchable-function-entry=2 > +endif > + > # Default value > head-y := arch/arm64/kernel/head.o > > --- a/arch/arm64/include/asm/ftrace.h > +++ b/arch/arm64/include/asm/ftrace.h > @@ -17,6 +17,19 @@ > #define MCOUNT_ADDR ((unsigned long)_mcount) > #define MCOUNT_INSN_SIZE AARCH64_INSN_SIZE > > +/* > + * DYNAMIC_FTRACE_WITH_REGS is implemented by adding 2 NOPs at the beginning > + * of each function, with the second NOP actually calling ftrace. In contrary > + * to a classic _mcount call, the call instruction to be modified is thus > + * the second one, and not the only one. > + */ > +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS > +#define ARCH_SUPPORTS_FTRACE_OPS 1 > +#define REC_IP_BRANCH_OFFSET AARCH64_INSN_SIZE > +#else > +#define REC_IP_BRANCH_OFFSET 0 > +#endif > + > #ifndef __ASSEMBLY__ > #include > > --- a/arch/arm64/kernel/Makefile > +++ b/arch/arm64/kernel/Makefile > @@ -7,9 +7,9 @@ CPPFLAGS_vmlinux.lds := -DTEXT_OFFSET=$( > AFLAGS_head.o := -DTEXT_OFFSET=$(TEXT_OFFSET) > CFLAGS_armv8_deprecated.o := -I$(src) > > -CFLAGS_REMOVE_ftrace.o = -pg > -CFLAGS_REMOVE_insn.o = -pg > -CFLAGS_REMOVE_return_address.o = -pg > +CFLAGS_REMOVE_ftrace.o = -pg $(CC_FLAGS_FTRACE) > +CFLAGS_REMOVE_insn.o = -pg $(CC_FLAGS_FTRACE) > +CFLAGS_REMOVE_return_address.o = -pg $(CC_FLAGS_FTRACE) > > # Object file lists. > arm64-obj-y := debug-monitors.o entry.o irq.o fpsimd.o \ > --- a/drivers/firmware/efi/libstub/Makefile > +++ b/drivers/firmware/efi/libstub/Makefile > @@ -13,7 +13,8 @@ cflags-$(CONFIG_X86) += -m$(BITS) -D__K > > # arm64 uses the full KBUILD_CFLAGS so it's necessary to explicitly > # disable the stackleak plugin > -cflags-$(CONFIG_ARM64) := $(subst -pg,,$(KBUILD_CFLAGS)) -fpie \ > +cflags-$(CONFIG_ARM64) := $(filter-out -pg $(CC_FLAGS_FTRACE)\ > + ,$(KBUILD_CFLAGS)) -fpie \ > $(DISABLE_STACKLEAK_PLUGIN) > cflags-$(CONFIG_ARM) := $(subst -pg,,$(KBUILD_CFLAGS)) \ > -fno-builtin -fpic -mno-single-pic-base > --- a/arch/arm64/kernel/entry-ftrace.S > +++ b/arch/arm64/kernel/entry-ftrace.S > @@ -13,6 +13,8 @@ > #include > #include > #include > +#include > +#include > > /* > * Gcc with -pg will put the following code in the beginning of each function: > @@ -122,6 +124,7 @@ skip_ftrace_call: // } > ENDPROC(_mcount) > > #else /* CONFIG_DYNAMIC_FTRACE */ > +#ifndef CONFIG_DYNAMIC_FTRACE_WITH_REGS > /* > * _mcount() is used to build the kernel with -pg option, but all the branch > * instructions to _mcount() are replaced to NOP initially at kernel start up, > @@ -159,6 +162,124 @@ GLOBAL(ftrace_graph_call) // ftrace_gra > > mcount_exit > ENDPROC(ftrace_caller) > +#else /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */ > + > +/* > + * Since no -pg or similar compiler flag is used, there should really be > + * no reference to _mcount; so do not define one. Only some value for > + * MCOUNT_ADDR is needed for comparison. Let it point here to have some > + * sort of magic value that can be recognised when debugging. > + */ > +GLOBAL(_mcount) > + ret /* make it differ from regs caller */ > + > +ENTRY(ftrace_regs_caller) > + /* callee's preliminary stack frame: */ > + stp fp, x9, [sp, #-16]! > + mov fp, sp > + > + /* our stack frame: */ > + stp fp, lr, [sp, #-S_FRAME_SIZE]! > + add x9, sp, #16 /* offset to pt_regs */ > + > + /* along with the _common code below, dump the complete > + * register set for inspection. > + */ > + stp x10, x11, [x9, #S_X10] > + stp x12, x13, [x9, #S_X12] > + stp x14, x15, [x9, #S_X14] > + stp x16, x17, [x9, #S_X16] > + stp x18, x19, [x9, #S_X18] > + stp x20, x21, [x9, #S_X20] > + stp x22, x23, [x9, #S_X22] > + stp x24, x25, [x9, #S_X24] > + stp x26, x27, [x9, #S_X26] > + > + b ftrace_common > +ENDPROC(ftrace_regs_caller) > + > +ENTRY(ftrace_caller) > + /* callee's preliminary stack frame: */ > + stp fp, x9, [sp, #-16]! > + mov fp, sp > + > + /* our stack frame: */ > + stp fp, lr, [sp, #-S_FRAME_SIZE]! > + add x9, sp, #16 /* offset to pt_regs */ > + > +ftrace_common: > + /* > + * At this point we have 2 new stack frames, and x9 pointing > + * at a pt_regs which we can populate as needed. At least the > + * argument registers need to be preserved, see > + * ftrace_common_return below. pt_regs at x9 is layed out so > + * that pt_regs.stackframe[] (last 16 bytes) maps to the > + * preliminary frame we created for the callee. > + */ > + > + /* save function arguments */ > + stp x0, x1, [x9] > + stp x2, x3, [x9, #S_X2] > + stp x4, x5, [x9, #S_X4] > + stp x6, x7, [x9, #S_X6] > + str x8, [x9, #S_X8] > + > + ldr x0, [fp] > + stp x28, x0, [x9, #S_X28] /* FP in pt_regs + "our" x28 */ > + > + /* The program counter just after the ftrace call site */ > + str lr, [x9, #S_PC] > + /* The stack pointer as it was on ftrace_caller entry... */ > + add x28, fp, #16 > + str x28, [x9, #S_SP] > + /* The link Register at callee entry */ > + ldr x28, [fp, 8] > + str x28, [x9, #S_LR] /* to pt_regs.r[30] */ > + > + ldr_l x2, function_trace_op, x0 > + ldr x1, [fp, #8] > + sub x0, lr, #8 /* function entry == IP */ > + mov x3, x9 /* pt_regs are @x9 */ > + > + mov fp, sp > + > +GLOBAL(ftrace_call) > + bl ftrace_stub > + > +#ifdef CONFIG_FUNCTION_GRAPH_TRACER > +GLOBAL(ftrace_graph_call) // ftrace_graph_caller(); > + nop // If enabled, this will be replaced > + // "b ftrace_graph_caller" > +#endif > + > +/* > + * GCC's patchable-function-entry implicitly disables IPA-RA, > + * so all non-argument registers are either scratch / dead > + * or callee-saved (within the ftrace framework). Function > + * arguments of the call we are intercepting right now however > + * need to be preserved in any case. > + */ > +ftrace_common_return: > + add x9, sp, #16 /* advance to pt_regs for restore */ > + > + ldp x0, x1, [x9] > + ldp x2, x3, [x9, #S_X2] > + ldp x4, x5, [x9, #S_X4] > + ldp x6, x7, [x9, #S_X6] > + ldr x8, [x9, #S_X8] > + > + ldp x28, fp, [x9, #S_X28] > + > + ldr lr, [x9, #S_LR] > + ldr x9, [x9, #S_PC] > + /* clean up both frames, ours and callee preliminary */ > + add sp, sp, #S_FRAME_SIZE + 16 > + > + ret x9 > + > +ENDPROC(ftrace_caller) > + > +#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */ > #endif /* CONFIG_DYNAMIC_FTRACE */ > > ENTRY(ftrace_stub) > @@ -176,12 +297,21 @@ ENDPROC(ftrace_stub) > * and run return_to_handler() later on its exit. > */ > ENTRY(ftrace_graph_caller) > +#ifndef CONFIG_DYNAMIC_FTRACE_WITH_REGS > mcount_get_pc x0 // function's pc > mcount_get_lr_addr x1 // pointer to function's saved lr > mcount_get_parent_fp x2 // parent's fp > bl prepare_ftrace_return // prepare_ftrace_return(pc, &lr, fp) > > mcount_exit > +#else > + add x9, sp, #16 /* advance to pt_regs to gather args */ > + ldr x0, [x9, #S_PC] /* pc */ > + add x1, x9, #S_LR /* &lr */ > + ldr x2, [x9, #S_STACKFRAME] /* fp */ > + bl prepare_ftrace_return > + b ftrace_common_return > +#endif > ENDPROC(ftrace_graph_caller) > > /* > --- a/arch/arm64/kernel/ftrace.c > +++ b/arch/arm64/kernel/ftrace.c > @@ -65,18 +65,66 @@ int ftrace_update_ftrace_func(ftrace_fun > return ftrace_modify_code(pc, 0, new, false); > } > > +#ifdef CONFIG_ARM64_MODULE_PLTS > +static int install_ftrace_trampoline(struct module *mod, unsigned long *addr) > +{ > + struct plt_entry trampoline, *mod_trampoline; > + > + /* Iterate over > + * mod->arch.ftrace_trampolines[MOD_ARCH_NR_FTRACE_TRAMPOLINES] > + * The assignment to various ftrace functions happens here. > + */ > + if (*addr == FTRACE_ADDR) > + mod_trampoline = &mod->arch.ftrace_trampolines[0]; > + else if (*addr == FTRACE_REGS_ADDR) > + mod_trampoline = &mod->arch.ftrace_trampolines[1]; > + else > + return -EINVAL; > + > + trampoline = get_plt_entry(*addr, mod_trampoline); > + > + if (!plt_entries_equal(mod_trampoline, &trampoline)) { > + > + /* point the trampoline at our ftrace entry point */ > + module_disable_ro(mod); > + *mod_trampoline = trampoline; > + module_enable_ro(mod, true); > + > + /* update trampoline before patching in the branch */ > + smp_wmb(); > + } > + *addr = (unsigned long)(void *)mod_trampoline; > + > + return 0; > +} > +#endif > + > +/* > + * Ftrace with regs generates the tracer calls as close as possible to > + * the function entry; no stack frame has been set up at that point. > + * In order to make another call e.g to ftrace_caller, the LR must be > + * saved from being overwritten. > + * Between two functions, and with IPA-RA turned off, the scratch registers > + * are available, so move the LR to x9 before calling into ftrace. > + * "mov x9, lr" is officially aliased from "orr x9, xzr, lr". > + */ > +#define QUICK_LR_SAVE aarch64_insn_gen_logical_shifted_reg( \ > + AARCH64_INSN_REG_9, AARCH64_INSN_REG_ZR, \ > + AARCH64_INSN_REG_LR, 0, AARCH64_INSN_VARIANT_64BIT, \ > + AARCH64_INSN_LOGIC_ORR) > + > /* > * Turn on the call to ftrace_caller() in instrumented function > */ > int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) > { > - unsigned long pc = rec->ip; > + unsigned long pc = rec->ip + REC_IP_BRANCH_OFFSET; > + int ret; > u32 old, new; > long offset = (long)pc - (long)addr; > > if (offset < -SZ_128M || offset >= SZ_128M) { > #ifdef CONFIG_ARM64_MODULE_PLTS > - struct plt_entry trampoline; > struct module *mod; > > /* > @@ -96,54 +144,65 @@ int ftrace_make_call(struct dyn_ftrace * > if (WARN_ON(!mod)) > return -EINVAL; > > - /* > - * There is only one ftrace trampoline per module. For now, > - * this is not a problem since on arm64, all dynamic ftrace > - * invocations are routed via ftrace_caller(). This will need > - * to be revisited if support for multiple ftrace entry points > - * is added in the future, but for now, the pr_err() below > - * deals with a theoretical issue only. > - */ > - trampoline = get_plt_entry(addr, mod->arch.ftrace_trampoline); > - if (!plt_entries_equal(mod->arch.ftrace_trampoline, > - &trampoline)) { > - if (!plt_entries_equal(mod->arch.ftrace_trampoline, > - &(struct plt_entry){})) { > - pr_err("ftrace: far branches to multiple entry points unsupported inside a single module\n"); > - return -EINVAL; > - } > - > - /* point the trampoline to our ftrace entry point */ > - module_disable_ro(mod); > - *mod->arch.ftrace_trampoline = trampoline; > - module_enable_ro(mod, true); > - > - /* update trampoline before patching in the branch */ > - smp_wmb(); > + /* Check against our well-known list of ftrace entry points */ > + if (addr == FTRACE_ADDR || addr == FTRACE_REGS_ADDR) { > + ret = install_ftrace_trampoline(mod, &addr); > + if (ret < 0) > + return ret; > } > - addr = (unsigned long)(void *)mod->arch.ftrace_trampoline; > + else > + return -EINVAL; > + > #else /* CONFIG_ARM64_MODULE_PLTS */ > return -EINVAL; > #endif /* CONFIG_ARM64_MODULE_PLTS */ > } > > old = aarch64_insn_gen_nop(); > + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS)) { > + new = QUICK_LR_SAVE; > + ret = ftrace_modify_code(pc - AARCH64_INSN_SIZE, > + old, new, true); > + if (ret) > + return ret; > + } > new = aarch64_insn_gen_branch_imm(pc, addr, AARCH64_INSN_BRANCH_LINK); > > return ftrace_modify_code(pc, old, new, true); > } > > +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS > +int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, > + unsigned long addr) > +{ > + unsigned long pc = rec->ip + REC_IP_BRANCH_OFFSET; > + u32 old, new; > + > + old = aarch64_insn_gen_branch_imm(pc, old_addr, true); > + new = aarch64_insn_gen_branch_imm(pc, addr, true); > + > + return ftrace_modify_code(pc, old, new, true); > +} > +#endif > + > /* > * Turn off the call to ftrace_caller() in instrumented function > */ > int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, > unsigned long addr) > { > - unsigned long pc = rec->ip; > + unsigned long pc = rec->ip + REC_IP_BRANCH_OFFSET; > bool validate = true; > + int ret; > u32 old = 0, new; > long offset = (long)pc - (long)addr; > > + /* -fpatchable-function-entry= does not generate a profiling call > + * initially; the NOPs are already there. > + */ > + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && addr == MCOUNT_ADDR) > + return 0; > + > if (offset < -SZ_128M || offset >= SZ_128M) { > #ifdef CONFIG_ARM64_MODULE_PLTS > u32 replaced; > @@ -188,7 +247,15 @@ int ftrace_make_nop(struct module *mod, > > new = aarch64_insn_gen_nop(); > > - return ftrace_modify_code(pc, old, new, validate); > + ret = ftrace_modify_code(pc, old, new, validate); > + if (ret) > + return ret; > + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS)) { > + old = QUICK_LR_SAVE; > + ret = ftrace_modify_code(pc - AARCH64_INSN_SIZE, > + old, new, true); > + } > + return ret; > } > > void arch_ftrace_update_code(int command) > --- a/include/asm-generic/vmlinux.lds.h > +++ b/include/asm-generic/vmlinux.lds.h > @@ -113,6 +113,7 @@ > #define MCOUNT_REC() . = ALIGN(8); \ > __start_mcount_loc = .; \ > KEEP(*(__mcount_loc)) \ > + KEEP(*(__patchable_function_entries)) \ > __stop_mcount_loc = .; > #else > #define MCOUNT_REC() > --- a/include/linux/compiler_types.h > +++ b/include/linux/compiler_types.h > @@ -223,8 +223,12 @@ struct ftrace_likely_data { > #if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__) > #define notrace __attribute__((hotpatch(0, 0))) > #else > +#if defined(CONFIG_ARM64) && defined(CONFIG_DYNAMIC_FTRACE_WITH_REGS) > +#define notrace __attribute__((patchable_function_entry(0))) > +#else > #define notrace __attribute__((no_instrument_function)) > #endif > +#endif > > /* > * it doesn't make sense on ARM (currently the only user of __naked) > --- a/arch/arm64/include/asm/module.h > +++ b/arch/arm64/include/asm/module.h > @@ -32,7 +32,8 @@ struct mod_arch_specific { > struct mod_plt_sec init; > > /* for CONFIG_DYNAMIC_FTRACE */ > - struct plt_entry *ftrace_trampoline; > + struct plt_entry *ftrace_trampolines; > +#define MOD_ARCH_NR_FTRACE_TRAMPOLINES 2 > }; > #endif > > --- a/arch/arm64/kernel/module.c > +++ b/arch/arm64/kernel/module.c > @@ -451,7 +451,7 @@ int module_finalize(const Elf_Ehdr *hdr, > #ifdef CONFIG_ARM64_MODULE_PLTS > if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE) && > !strcmp(".text.ftrace_trampoline", secstrs + s->sh_name)) > - me->arch.ftrace_trampoline = (void *)s->sh_addr; > + me->arch.ftrace_trampolines = (void *)s->sh_addr; > #endif > } > > --- a/arch/arm64/kernel/module-plts.c > +++ b/arch/arm64/kernel/module-plts.c > @@ -323,7 +323,8 @@ int module_frob_arch_sections(Elf_Ehdr * > tramp->sh_type = SHT_NOBITS; > tramp->sh_flags = SHF_EXECINSTR | SHF_ALLOC; > tramp->sh_addralign = __alignof__(struct plt_entry); > - tramp->sh_size = sizeof(struct plt_entry); > + tramp->sh_size = MOD_ARCH_NR_FTRACE_TRAMPOLINES > + * sizeof(struct plt_entry); > } > > return 0; > --- a/arch/arm64/include/asm/assembler.h > +++ b/arch/arm64/include/asm/assembler.h > @@ -159,6 +159,7 @@ > /* > * Register aliases. > */ > +fp .req x29 // frame pointer > lr .req x30 // link register > > /*