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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /arch/arm64/kernel/alternative.c
Initial import
Diffstat (limited to 'arch/arm64/kernel/alternative.c')
-rw-r--r--arch/arm64/kernel/alternative.c85
1 files changed, 85 insertions, 0 deletions
diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c
new file mode 100644
index 000000000..28f8365ed
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+++ b/arch/arm64/kernel/alternative.c
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+/*
+ * 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[];
+
+struct alt_region {
+ struct alt_instr *begin;
+ struct alt_instr *end;
+};
+
+static int __apply_alternatives(void *alt_region)
+{
+ struct alt_instr *alt;
+ struct alt_region *region = alt_region;
+ u8 *origptr, *replptr;
+
+ for (alt = region->begin; alt < region->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_all(void)
+{
+ struct alt_region region = {
+ .begin = __alt_instructions,
+ .end = __alt_instructions_end,
+ };
+
+ /* better not try code patching on a live SMP system */
+ stop_machine(__apply_alternatives, &region, NULL);
+}
+
+void apply_alternatives(void *start, size_t length)
+{
+ struct alt_region region = {
+ .begin = start,
+ .end = start + length,
+ };
+
+ __apply_alternatives(&region);
+}
+
+void free_alternatives_memory(void)
+{
+ free_reserved_area(__alt_instructions, __alt_instructions_end,
+ 0, "alternatives");
+}