From mboxrd@z Thu Jan 1 00:00:00 1970 From: ard.biesheuvel@linaro.org (Ard Biesheuvel) Date: Fri, 18 Sep 2015 17:39:59 +0200 Subject: [PATCH v1 1/2] arm64: introduce infrastructure for emitting veneers at module reloc time In-Reply-To: <1442590800-14645-1-git-send-email-ard.biesheuvel@linaro.org> References: <1442590800-14645-1-git-send-email-ard.biesheuvel@linaro.org> Message-ID: <1442590800-14645-2-git-send-email-ard.biesheuvel@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Introduce a framework for arm64 that allows errata fixups to be implemented by replacing problematic instruction sequences with calls into veneers that are generated on the fly. This is based on the module PLT support for ARM. Signed-off-by: Ard Biesheuvel --- arch/arm64/Kconfig | 3 + arch/arm64/include/asm/module.h | 11 ++ arch/arm64/kernel/Makefile | 1 + arch/arm64/kernel/mod_veneers.c | 105 ++++++++++++++++++++ 4 files changed, 120 insertions(+) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 7d95663c0160..b591aac06fed 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -68,6 +68,7 @@ config ARM64 select HAVE_GENERIC_DMA_COHERENT select HAVE_HW_BREAKPOINT if PERF_EVENTS select HAVE_MEMBLOCK + select HAVE_MOD_ARCH_SPECIFIC if ARM64_MOD_VENEERS select HAVE_PATA_PLATFORM select HAVE_PERF_EVENTS select HAVE_PERF_REGS @@ -333,6 +334,8 @@ config ARM64_ERRATUM_845719 endmenu +config ARM64_MOD_VENEERS + bool choice prompt "Page size" diff --git a/arch/arm64/include/asm/module.h b/arch/arm64/include/asm/module.h index e80e232b730e..d9ce63386e33 100644 --- a/arch/arm64/include/asm/module.h +++ b/arch/arm64/include/asm/module.h @@ -20,4 +20,15 @@ #define MODULE_ARCH_VERMAGIC "aarch64" +#ifdef CONFIG_HAVE_MOD_ARCH_SPECIFIC +struct mod_arch_specific { +#ifdef CONFIG_ARM64_MOD_VENEERS + struct veneer_section { + int sec_index; + unsigned int sec_offset; + } core, init; +#endif +}; +#endif + #endif /* __ASM_MODULE_H */ diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 22dc9bc781be..29eb0c8c33a8 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -25,6 +25,7 @@ arm64-obj-$(CONFIG_COMPAT) += sys32.o kuser32.o signal32.o \ ../../arm/kernel/opcodes.o arm64-obj-$(CONFIG_FUNCTION_TRACER) += ftrace.o entry-ftrace.o arm64-obj-$(CONFIG_MODULES) += arm64ksyms.o module.o +arm64-obj-$(CONFIG_ARM64_MOD_VENEERS) += mod_veneers.o arm64-obj-$(CONFIG_PERF_EVENTS) += perf_regs.o perf_callchain.o arm64-obj-$(CONFIG_HW_PERF_EVENTS) += perf_event.o arm64-obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o diff --git a/arch/arm64/kernel/mod_veneers.c b/arch/arm64/kernel/mod_veneers.c new file mode 100644 index 000000000000..9649c4f305bd --- /dev/null +++ b/arch/arm64/kernel/mod_veneers.c @@ -0,0 +1,105 @@ +/* + * Copyright (C) 2015 Linaro Ltd. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include +#include +#include + +static bool in_init(const struct module *mod, u64 addr) +{ + return addr - (u64)mod->module_init < mod->init_size; +} + +static void *alloc_veneer(struct module *mod, u64 loc, int size, + Elf64_Shdr *sechdrs) +{ + struct veneer_section *vs; + void *ret; + + if (in_init(mod, loc) && mod->arch.init.sec_index != -1) + vs = &mod->arch.init; + else + vs = &mod->arch.core; + + ret = (void*)sechdrs[vs->sec_index].sh_addr + vs->sec_offset; + vs->sec_offset += size; + + return ret; +} + +/* estimate the maximum size of the veneer for this relocation */ +static unsigned long get_veneers_size(Elf64_Addr base, const Elf64_Rela *rel, + int num) +{ + unsigned long ret = 0; + int i; + + for (i = 0; i < num; i++) + switch (ELF64_R_TYPE(rel[i].r_info)) { + } + return ret; +} + +int module_frob_arch_sections(Elf64_Ehdr *ehdr, Elf64_Shdr *sechdrs, + char *secstrings, struct module *mod) +{ + unsigned long core_veneers_maxsize = 0, init_veneers_maxsize = 0; + int core_sec_idx = -1, init_sec_idx = -1; + int i; + + /* find the .text and .init.text sections */ + for (i = 0; i < ehdr->e_shnum; i++) { + const char *sec_name = secstrings + sechdrs[i].sh_name; + + if (strcmp(sec_name, ".text") == 0) + core_sec_idx = i; + else if (strcmp(sec_name, ".init.text") == 0) + init_sec_idx = i; + + if (core_sec_idx != -1 && init_sec_idx != -1) + break; + } + + for (i = 0; i < ehdr->e_shnum; i++) { + Elf64_Shdr *s = &sechdrs[i]; + Elf64_Rela *rels = (void *)ehdr + s->sh_offset; + int numrels = s->sh_size / sizeof(Elf64_Rela); + Elf64_Shdr *dstsec = sechdrs + s->sh_info; + + if (s->sh_type != SHT_RELA) + continue; + + if (strstr(secstrings + s->sh_name, ".init")) + init_veneers_maxsize += get_veneers_size( + dstsec->sh_addr, rels, numrels); + else + core_veneers_maxsize += get_veneers_size( + dstsec->sh_addr, rels, numrels); + } + + if (init_sec_idx == -1 && init_veneers_maxsize > 0) + core_veneers_maxsize += init_veneers_maxsize; + + if (core_sec_idx == -1 && core_veneers_maxsize > 0) { + pr_err("%s: .text section missing\n", mod->name); + return -ENOEXEC; + } + + mod->arch.core.sec_index = core_sec_idx; + mod->arch.core.sec_offset = sechdrs[core_sec_idx].sh_size; + sechdrs[core_sec_idx].sh_size += core_veneers_maxsize; + + mod->arch.init.sec_index = init_sec_idx; + if (init_sec_idx != -1) { + mod->arch.init.sec_offset = sechdrs[init_sec_idx].sh_size; + sechdrs[init_sec_idx].sh_size += init_veneers_maxsize; + } + pr_debug("module %s: core_veneers_maxsize == %lu, init_veneers_maxsize == %lu\n", + mod->name, core_veneers_maxsize, init_veneers_maxsize); + return 0; +} -- 1.9.1