Signed-off-by: AKASHI Takahiro takahiro.akashi@linaro.org --- arch/arm64/Kconfig | 3 ++ arch/arm64/include/asm/livepatch.h | 38 ++++++++++++++++++++ arch/arm64/kernel/Makefile | 1 + arch/arm64/kernel/livepatch.c | 68 ++++++++++++++++++++++++++++++++++++ 4 files changed, 110 insertions(+) create mode 100644 arch/arm64/include/asm/livepatch.h create mode 100644 arch/arm64/kernel/livepatch.c
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index c3678ed..d4b5bac 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -61,6 +61,7 @@ config ARM64 select HAVE_FUNCTION_GRAPH_TRACER select HAVE_GENERIC_DMA_COHERENT select HAVE_HW_BREAKPOINT if PERF_EVENTS + select HAVE_LIVEPATCH select HAVE_MEMBLOCK select HAVE_PATA_PLATFORM select HAVE_PERF_EVENTS @@ -612,6 +613,8 @@ config SETEND_EMULATION If unsure, say Y endif
+source "kernel/livepatch/Kconfig" + endmenu
menu "Boot options" diff --git a/arch/arm64/include/asm/livepatch.h b/arch/arm64/include/asm/livepatch.h new file mode 100644 index 0000000..590d139 --- /dev/null +++ b/arch/arm64/include/asm/livepatch.h @@ -0,0 +1,38 @@ +/* + * Copyright (C) 2015 Linaro Limited + * Author: AKASHI Takahiro takahiro.akashi@linaro.org + * + * 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. + */ +#ifndef __ASM_LIVEPATCH_H +#define __ASM_LIVEPATCH_H + +#include <linux/module.h> +#include <linux/ftrace.h> + +#ifdef CONFIG_LIVEPATCH +static inline int klp_check_compiler_support(void) +{ + return 0; +} +extern int klp_write_module_reloc(struct module *mod, unsigned long type, + unsigned long loc, unsigned long value); + +extern unsigned long ftrace_lookup_mcount(unsigned long addr); + +static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip) +{ + regs->regs[30] = ip; +} + +static inline unsigned long klp_arch_lookup_mcount(unsigned long addr) +{ + return ftrace_lookup_mcount(addr); +} +#else +#error Live patching support is disabled; check CONFIG_LIVEPATCH +#endif + +#endif /* __ASM_LIVEPATCH_H */ diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 5ee07ee..7614990 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -35,6 +35,7 @@ arm64-obj-$(CONFIG_KGDB) += kgdb.o arm64-obj-$(CONFIG_EFI) += efi.o efi-stub.o efi-entry.o arm64-obj-$(CONFIG_PCI) += pci.o arm64-obj-$(CONFIG_ARMV8_DEPRECATED) += armv8_deprecated.o +arm64-obj-$(CONFIG_LIVEPATCH) += livepatch.o
obj-y += $(arm64-obj-y) vdso/ obj-m += $(arm64-obj-m) diff --git a/arch/arm64/kernel/livepatch.c b/arch/arm64/kernel/livepatch.c new file mode 100644 index 0000000..abe4947 --- /dev/null +++ b/arch/arm64/kernel/livepatch.c @@ -0,0 +1,68 @@ +/* + * livepatch.c - arm64-specific Kernel Live Patching Core + * + * Copyright (C) 2015 Linaro Limited + * Author: AKASHI Takahiro takahiro.akashi@linaro.org + * + * 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 <linux/module.h> +#include <asm/cacheflush.h> +#include <asm/elf.h> +#include <asm/insn.h> +#include <asm/livepatch.h> + +/** + * klp_write_module_reloc() - write a relocation in a module + * @mod: module in which the section to be modified is found + * @type: ELF relocation type (see asm/elf.h) + * @loc: address that the relocation should be written to + * @value: relocation value (sym address + addend) + * + * This function writes a relocation to the specified location for + * a particular module. + */ +int klp_write_module_reloc(struct module *mod, unsigned long type, + unsigned long loc, unsigned long value) +{ + unsigned long core = (unsigned long)mod->module_core; + unsigned long core_ro_size = mod->core_ro_size; + unsigned long core_size = mod->core_size; + bool readonly; + u32 new; + int ret; + + switch (type) { + case R_AARCH64_NONE: + return 0; + case R_AARCH64_CALL26: + break; + default: + /* unsupported relocation type */ + return -EINVAL; + } + + if (loc < core || loc >= core + core_size) + /* loc does not point to any symbol inside the module */ + return -EINVAL; + + if (loc < core + core_ro_size) + readonly = true; + else + readonly = false; + + if (readonly) + set_memory_rw(loc & PAGE_MASK, 1); + + new = aarch64_insn_gen_branch_imm(loc, value, + AARCH64_INSN_BRANCH_NOLINK); + ret = aarch64_insn_patch_text_nosync((void *)loc, new); + + if (readonly) + set_memory_ro(loc & PAGE_MASK, 1); + + return ret; +}