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-rw-r--r--arch/arm/kernel/patch.c75
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 0000000..07314af
--- /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);
+ }
+}