1 files changed, 75 insertions, 0 deletions

diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c
new file mode 100644
index 000000000000..07314af47733
--- /dev/null
+++ b/arch/arm/kernel/patch.c
@@ -0,0 +1,75 @@
+#include <linux/kernel.h>
+#include <linux/kprobes.h>
+#include <linux/stop_machine.h>
+
+#include <asm/cacheflush.h>
+#include <asm/smp_plat.h>
+#include <asm/opcodes.h>
+
+#include "patch.h"
+
+struct patch {
+        void *addr;
+        unsigned int insn;
+};
+
+void __kprobes __patch_text(void *addr, unsigned int insn)
+{
+        bool thumb2 = IS_ENABLED(CONFIG_THUMB2_KERNEL);
+        int size;
+
+        if (thumb2 && __opcode_is_thumb16(insn)) {
+                *(u16 *)addr = __opcode_to_mem_thumb16(insn);
+                size = sizeof(u16);
+        } else if (thumb2 && ((uintptr_t)addr & 2)) {
+                u16 first = __opcode_thumb32_first(insn);
+                u16 second = __opcode_thumb32_second(insn);
+                u16 *addrh = addr;
+
+                addrh[0] = __opcode_to_mem_thumb16(first);
+                addrh[1] = __opcode_to_mem_thumb16(second);
+
+                size = sizeof(u32);
+        } else {
+                if (thumb2)
+                        insn = __opcode_to_mem_thumb32(insn);
+                else
+                        insn = __opcode_to_mem_arm(insn);
+
+                *(u32 *)addr = insn;
+                size = sizeof(u32);
+        }
+
+        flush_icache_range((uintptr_t)(addr),
+                           (uintptr_t)(addr) + size);
+}
+
+static int __kprobes patch_text_stop_machine(void *data)
+{
+        struct patch *patch = data;
+
+        __patch_text(patch->addr, patch->insn);
+
+        return 0;
+}
+
+void __kprobes patch_text(void *addr, unsigned int insn)
+{
+        struct patch patch = {
+                .addr = addr,
+                .insn = insn,
+        };
+
+        if (cache_ops_need_broadcast()) {
+                stop_machine(patch_text_stop_machine, &patch, cpu_online_mask);
+        } else {
+                bool straddles_word = IS_ENABLED(CONFIG_THUMB2_KERNEL)
+                                      && __opcode_is_thumb32(insn)
+                                      && ((uintptr_t)addr & 2);
+
+                if (straddles_word)
+                        stop_machine(patch_text_stop_machine, &patch, NULL);
+                else
+                        __patch_text(addr, insn);
+        }
+}