diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/include/asm/alternative-asm.h | 16 | ||||
| -rw-r--r-- | arch/arm64/include/asm/alternative.h | 43 | ||||
| -rw-r--r-- | arch/arm64/kernel/Makefile | 2 | ||||
| -rw-r--r-- | arch/arm64/kernel/alternative.c | 64 | ||||
| -rw-r--r-- | arch/arm64/kernel/smp.c | 2 | ||||
| -rw-r--r-- | arch/arm64/kernel/vmlinux.lds.S | 11 | ||||
| -rw-r--r-- | arch/arm64/mm/init.c | 2 |
7 files changed, 139 insertions, 1 deletions
diff --git a/arch/arm64/include/asm/alternative-asm.h b/arch/arm64/include/asm/alternative-asm.h new file mode 100644 index 000000000000..5ee9340459b8 --- /dev/null +++ b/arch/arm64/include/asm/alternative-asm.h @@ -0,0 +1,16 @@ +#ifndef __ASM_ALTERNATIVE_ASM_H +#define __ASM_ALTERNATIVE_ASM_H + +#ifdef __ASSEMBLY__ + +.macro altinstruction_entry orig_offset alt_offset feature orig_len alt_len + .word \orig_offset - . + .word \alt_offset - . + .hword \feature + .byte \orig_len + .byte \alt_len +.endm + +#endif /* __ASSEMBLY__ */ + +#endif /* __ASM_ALTERNATIVE_ASM_H */ diff --git a/arch/arm64/include/asm/alternative.h b/arch/arm64/include/asm/alternative.h new file mode 100644 index 000000000000..f6d206e7f9e9 --- /dev/null +++ b/arch/arm64/include/asm/alternative.h @@ -0,0 +1,43 @@ +#ifndef __ASM_ALTERNATIVE_H +#define __ASM_ALTERNATIVE_H + +#include <linux/types.h> +#include <linux/stddef.h> +#include <linux/stringify.h> + +struct alt_instr { + s32 orig_offset; /* offset to original instruction */ + s32 alt_offset; /* offset to replacement instruction */ + u16 cpufeature; /* cpufeature bit set for replacement */ + u8 orig_len; /* size of original instruction(s) */ + u8 alt_len; /* size of new instruction(s), <= orig_len */ +}; + +void apply_alternatives(void); +void free_alternatives_memory(void); + +#define ALTINSTR_ENTRY(feature) \ + " .word 661b - .\n" /* label */ \ + " .word 663f - .\n" /* new instruction */ \ + " .hword " __stringify(feature) "\n" /* feature bit */ \ + " .byte 662b-661b\n" /* source len */ \ + " .byte 664f-663f\n" /* replacement len */ + +/* alternative assembly primitive: */ +#define ALTERNATIVE(oldinstr, newinstr, feature) \ + "661:\n\t" \ + oldinstr "\n" \ + "662:\n" \ + ".pushsection .altinstructions,\"a\"\n" \ + ALTINSTR_ENTRY(feature) \ + ".popsection\n" \ + ".pushsection .altinstr_replacement, \"a\"\n" \ + "663:\n\t" \ + newinstr "\n" \ + "664:\n\t" \ + ".popsection\n\t" \ + ".if ((664b-663b) != (662b-661b))\n\t" \ + " .error \"Alternatives instruction length mismatch\"\n\t"\ + ".endif\n" + +#endif /* __ASM_ALTERNATIVE_H */ diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index b36ebd0aacbb..591a65dc5c9b 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -16,7 +16,7 @@ arm64-obj-y := cputable.o debug-monitors.o entry.o irq.o fpsimd.o \ entry-fpsimd.o process.o ptrace.o setup.o signal.o \ sys.o stacktrace.o time.o traps.o io.o vdso.o \ hyp-stub.o psci.o cpu_ops.o insn.o return_address.o \ - cpuinfo.o + cpuinfo.o alternative.o arm64-obj-$(CONFIG_COMPAT) += sys32.o kuser32.o signal32.o \ sys_compat.o \ diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c new file mode 100644 index 000000000000..1a3badab800a --- /dev/null +++ b/arch/arm64/kernel/alternative.c @@ -0,0 +1,64 @@ +/* + * alternative runtime patching + * inspired by the x86 version + * + * Copyright (C) 2014 ARM 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. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#define pr_fmt(fmt) "alternatives: " fmt + +#include <linux/init.h> +#include <linux/cpu.h> +#include <asm/cacheflush.h> +#include <asm/alternative.h> +#include <asm/cpufeature.h> +#include <linux/stop_machine.h> + +extern struct alt_instr __alt_instructions[], __alt_instructions_end[]; + +static int __apply_alternatives(void *dummy) +{ + struct alt_instr *alt; + u8 *origptr, *replptr; + + for (alt = __alt_instructions; alt < __alt_instructions_end; alt++) { + if (!cpus_have_cap(alt->cpufeature)) + continue; + + BUG_ON(alt->alt_len > alt->orig_len); + + pr_info_once("patching kernel code\n"); + + origptr = (u8 *)&alt->orig_offset + alt->orig_offset; + replptr = (u8 *)&alt->alt_offset + alt->alt_offset; + memcpy(origptr, replptr, alt->alt_len); + flush_icache_range((uintptr_t)origptr, + (uintptr_t)(origptr + alt->alt_len)); + } + + return 0; +} + +void apply_alternatives(void) +{ + /* better not try code patching on a live SMP system */ + stop_machine(__apply_alternatives, NULL, NULL); +} + +void free_alternatives_memory(void) +{ + free_reserved_area(__alt_instructions, __alt_instructions_end, + 0, "alternatives"); +} diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index b06d1d90ee8c..0ef87896e4ae 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -37,6 +37,7 @@ #include <linux/of.h> #include <linux/irq_work.h> +#include <asm/alternative.h> #include <asm/atomic.h> #include <asm/cacheflush.h> #include <asm/cpu.h> @@ -309,6 +310,7 @@ void cpu_die(void) void __init smp_cpus_done(unsigned int max_cpus) { pr_info("SMP: Total of %d processors activated.\n", num_online_cpus()); + apply_alternatives(); } void __init smp_prepare_boot_cpu(void) diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index 4596f46d0244..3236727be2b9 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -116,6 +116,17 @@ SECTIONS . = ALIGN(PAGE_SIZE); __init_end = .; + . = ALIGN(4); + .altinstructions : { + __alt_instructions = .; + *(.altinstructions) + __alt_instructions_end = .; + } + .altinstr_replacement : { + *(.altinstr_replacement) + } + + . = ALIGN(PAGE_SIZE); _data = .; _sdata = .; RW_DATA_SECTION(64, PAGE_SIZE, THREAD_SIZE) diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 494297c698ca..bac492c12fcc 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -39,6 +39,7 @@ #include <asm/setup.h> #include <asm/sizes.h> #include <asm/tlb.h> +#include <asm/alternative.h> #include "mm.h" @@ -325,6 +326,7 @@ void __init mem_init(void) void free_initmem(void) { free_initmem_default(0); + free_alternatives_memory(); } #ifdef CONFIG_BLK_DEV_INITRD |