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-rw-r--r--arch/arm64/kernel/Makefile2
-rw-r--r--arch/arm64/kernel/alternative.c64
-rw-r--r--arch/arm64/kernel/smp.c2
-rw-r--r--arch/arm64/kernel/vmlinux.lds.S11
4 files changed, 78 insertions, 1 deletions
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)