v4.19.13 snapshot.
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
new file mode 100644
index 0000000..ee673c0
--- /dev/null
+++ b/arch/arm/kernel/ftrace.c
@@ -0,0 +1,298 @@
+/*
+ * Dynamic function tracing support.
+ *
+ * Copyright (C) 2008 Abhishek Sagar <sagar.abhishek@gmail.com>
+ * Copyright (C) 2010 Rabin Vincent <rabin@rab.in>
+ *
+ * For licencing details, see COPYING.
+ *
+ * Defines low-level handling of mcount calls when the kernel
+ * is compiled with the -pg flag. When using dynamic ftrace, the
+ * mcount call-sites get patched with NOP till they are enabled.
+ * All code mutation routines here are called under stop_machine().
+ */
+
+#include <linux/ftrace.h>
+#include <linux/uaccess.h>
+#include <linux/module.h>
+#include <linux/stop_machine.h>
+
+#include <asm/cacheflush.h>
+#include <asm/opcodes.h>
+#include <asm/ftrace.h>
+#include <asm/insn.h>
+#include <asm/set_memory.h>
+
+#ifdef CONFIG_THUMB2_KERNEL
+#define NOP 0xf85deb04 /* pop.w {lr} */
+#else
+#define NOP 0xe8bd4000 /* pop {lr} */
+#endif
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+static int __ftrace_modify_code(void *data)
+{
+ int *command = data;
+
+ set_kernel_text_rw();
+ ftrace_modify_all_code(*command);
+ set_kernel_text_ro();
+
+ return 0;
+}
+
+void arch_ftrace_update_code(int command)
+{
+ stop_machine(__ftrace_modify_code, &command, NULL);
+}
+
+#ifdef CONFIG_OLD_MCOUNT
+#define OLD_MCOUNT_ADDR ((unsigned long) mcount)
+#define OLD_FTRACE_ADDR ((unsigned long) ftrace_caller_old)
+
+#define OLD_NOP 0xe1a00000 /* mov r0, r0 */
+
+static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
+{
+ return rec->arch.old_mcount ? OLD_NOP : NOP;
+}
+
+static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
+{
+ if (!rec->arch.old_mcount)
+ return addr;
+
+ if (addr == MCOUNT_ADDR)
+ addr = OLD_MCOUNT_ADDR;
+ else if (addr == FTRACE_ADDR)
+ addr = OLD_FTRACE_ADDR;
+
+ return addr;
+}
+#else
+static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
+{
+ return NOP;
+}
+
+static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
+{
+ return addr;
+}
+#endif
+
+int ftrace_arch_code_modify_prepare(void)
+{
+ set_all_modules_text_rw();
+ return 0;
+}
+
+int ftrace_arch_code_modify_post_process(void)
+{
+ set_all_modules_text_ro();
+ /* Make sure any TLB misses during machine stop are cleared. */
+ flush_tlb_all();
+ return 0;
+}
+
+static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
+{
+ return arm_gen_branch_link(pc, addr);
+}
+
+static int ftrace_modify_code(unsigned long pc, unsigned long old,
+ unsigned long new, bool validate)
+{
+ unsigned long replaced;
+
+ if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
+ old = __opcode_to_mem_thumb32(old);
+ new = __opcode_to_mem_thumb32(new);
+ } else {
+ old = __opcode_to_mem_arm(old);
+ new = __opcode_to_mem_arm(new);
+ }
+
+ if (validate) {
+ if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE))
+ return -EFAULT;
+
+ if (replaced != old)
+ return -EINVAL;
+ }
+
+ if (probe_kernel_write((void *)pc, &new, MCOUNT_INSN_SIZE))
+ return -EPERM;
+
+ flush_icache_range(pc, pc + MCOUNT_INSN_SIZE);
+
+ return 0;
+}
+
+int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+ unsigned long pc;
+ unsigned long new;
+ int ret;
+
+ pc = (unsigned long)&ftrace_call;
+ new = ftrace_call_replace(pc, (unsigned long)func);
+
+ ret = ftrace_modify_code(pc, 0, new, false);
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+ if (!ret) {
+ pc = (unsigned long)&ftrace_regs_call;
+ new = ftrace_call_replace(pc, (unsigned long)func);
+
+ ret = ftrace_modify_code(pc, 0, new, false);
+ }
+#endif
+
+#ifdef CONFIG_OLD_MCOUNT
+ if (!ret) {
+ pc = (unsigned long)&ftrace_call_old;
+ new = ftrace_call_replace(pc, (unsigned long)func);
+
+ ret = ftrace_modify_code(pc, 0, new, false);
+ }
+#endif
+
+ return ret;
+}
+
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+ unsigned long new, old;
+ unsigned long ip = rec->ip;
+
+ old = ftrace_nop_replace(rec);
+
+ new = ftrace_call_replace(ip, adjust_address(rec, addr));
+
+ return ftrace_modify_code(rec->ip, old, new, true);
+}
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+
+int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
+ unsigned long addr)
+{
+ unsigned long new, old;
+ unsigned long ip = rec->ip;
+
+ old = ftrace_call_replace(ip, adjust_address(rec, old_addr));
+
+ new = ftrace_call_replace(ip, adjust_address(rec, addr));
+
+ return ftrace_modify_code(rec->ip, old, new, true);
+}
+
+#endif
+
+int ftrace_make_nop(struct module *mod,
+ struct dyn_ftrace *rec, unsigned long addr)
+{
+ unsigned long ip = rec->ip;
+ unsigned long old;
+ unsigned long new;
+ int ret;
+
+ old = ftrace_call_replace(ip, adjust_address(rec, addr));
+ new = ftrace_nop_replace(rec);
+ ret = ftrace_modify_code(ip, old, new, true);
+
+#ifdef CONFIG_OLD_MCOUNT
+ if (ret == -EINVAL && addr == MCOUNT_ADDR) {
+ rec->arch.old_mcount = true;
+
+ old = ftrace_call_replace(ip, adjust_address(rec, addr));
+ new = ftrace_nop_replace(rec);
+ ret = ftrace_modify_code(ip, old, new, true);
+ }
+#endif
+
+ return ret;
+}
+
+int __init ftrace_dyn_arch_init(void)
+{
+ return 0;
+}
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
+ unsigned long frame_pointer)
+{
+ unsigned long return_hooker = (unsigned long) &return_to_handler;
+ unsigned long old;
+
+ if (unlikely(atomic_read(¤t->tracing_graph_pause)))
+ return;
+
+ old = *parent;
+ *parent = return_hooker;
+
+ if (function_graph_enter(old, self_addr, frame_pointer, NULL))
+ *parent = old;
+}
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+extern unsigned long ftrace_graph_call;
+extern unsigned long ftrace_graph_call_old;
+extern void ftrace_graph_caller_old(void);
+extern unsigned long ftrace_graph_regs_call;
+extern void ftrace_graph_regs_caller(void);
+
+static int __ftrace_modify_caller(unsigned long *callsite,
+ void (*func) (void), bool enable)
+{
+ unsigned long caller_fn = (unsigned long) func;
+ unsigned long pc = (unsigned long) callsite;
+ unsigned long branch = arm_gen_branch(pc, caller_fn);
+ unsigned long nop = 0xe1a00000; /* mov r0, r0 */
+ unsigned long old = enable ? nop : branch;
+ unsigned long new = enable ? branch : nop;
+
+ return ftrace_modify_code(pc, old, new, true);
+}
+
+static int ftrace_modify_graph_caller(bool enable)
+{
+ int ret;
+
+ ret = __ftrace_modify_caller(&ftrace_graph_call,
+ ftrace_graph_caller,
+ enable);
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+ if (!ret)
+ ret = __ftrace_modify_caller(&ftrace_graph_regs_call,
+ ftrace_graph_regs_caller,
+ enable);
+#endif
+
+
+#ifdef CONFIG_OLD_MCOUNT
+ if (!ret)
+ ret = __ftrace_modify_caller(&ftrace_graph_call_old,
+ ftrace_graph_caller_old,
+ enable);
+#endif
+
+ return ret;
+}
+
+int ftrace_enable_ftrace_graph_caller(void)
+{
+ return ftrace_modify_graph_caller(true);
+}
+
+int ftrace_disable_ftrace_graph_caller(void)
+{
+ return ftrace_modify_graph_caller(false);
+}
+#endif /* CONFIG_DYNAMIC_FTRACE */
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */