1 files changed, 310 insertions, 0 deletions
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
new file mode 100644
index 000000000..a0b6d1e38
--- /dev/null
+++ b/arch/arm/kernel/ftrace.c
@@ -0,0 +1,310 @@
+/*
+ * 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>
+#include <asm/stacktrace.h>
+#include <asm/patch.h>
+
+/*
+ * The compiler emitted profiling hook consists of
+ *
+ *   PUSH    {LR}
+ *   BL	     __gnu_mcount_nc
+ *
+ * To turn this combined sequence into a NOP, we need to restore the value of
+ * SP before the PUSH. Let's use an ADD rather than a POP into LR, as LR is not
+ * modified anyway, and reloading LR from memory is highly likely to be less
+ * efficient.
+ */
+#ifdef CONFIG_THUMB2_KERNEL
+#define	NOP		0xf10d0d04	/* add.w sp, sp, #4 */
+#else
+#define	NOP		0xe28dd004	/* add   sp, sp, #4 */
+#endif
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+static int __ftrace_modify_code(void *data)
+{
+	int *command = data;
+
+	ftrace_modify_all_code(*command);
+
+	return 0;
+}
+
+void arch_ftrace_update_code(int command)
+{
+	stop_machine(__ftrace_modify_code, &command, NULL);
+}
+
+static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
+{
+	return NOP;
+}
+
+void ftrace_caller_from_init(void);
+void ftrace_regs_caller_from_init(void);
+
+static unsigned long __ref adjust_address(struct dyn_ftrace *rec,
+					  unsigned long addr)
+{
+	if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE) ||
+	    system_state >= SYSTEM_FREEING_INITMEM ||
+	    likely(!is_kernel_inittext(rec->ip)))
+		return addr;
+	if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) ||
+	    addr == (unsigned long)&ftrace_caller)
+		return (unsigned long)&ftrace_caller_from_init;
+	return (unsigned long)&ftrace_regs_caller_from_init;
+}
+
+void ftrace_arch_code_modify_prepare(void)
+{
+}
+
+void ftrace_arch_code_modify_post_process(void)
+{
+	/* Make sure any TLB misses during machine stop are cleared. */
+	flush_tlb_all();
+}
+
+static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr,
+					 bool warn)
+{
+	return arm_gen_branch_link(pc, addr, warn);
+}
+
+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);
+	else
+		old = __opcode_to_mem_arm(old);
+
+	if (validate) {
+		if (copy_from_kernel_nofault(&replaced, (void *)pc,
+				MCOUNT_INSN_SIZE))
+			return -EFAULT;
+
+		if (replaced != old)
+			return -EINVAL;
+	}
+
+	__patch_text((void *)pc, new);
+
+	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, true);
+
+	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, true);
+
+		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;
+	unsigned long aaddr = adjust_address(rec, addr);
+	struct module *mod = NULL;
+
+#ifdef CONFIG_ARM_MODULE_PLTS
+	mod = rec->arch.mod;
+#endif
+
+	old = ftrace_nop_replace(rec);
+
+	new = ftrace_call_replace(ip, aaddr, !mod);
+#ifdef CONFIG_ARM_MODULE_PLTS
+	if (!new && mod) {
+		aaddr = get_module_plt(mod, ip, aaddr);
+		new = ftrace_call_replace(ip, aaddr, true);
+	}
+#endif
+
+	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), true);
+
+	new = ftrace_call_replace(ip, adjust_address(rec, addr), true);
+
+	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 aaddr = adjust_address(rec, addr);
+	unsigned long ip = rec->ip;
+	unsigned long old;
+	unsigned long new;
+	int ret;
+
+#ifdef CONFIG_ARM_MODULE_PLTS
+	/* mod is only supplied during module loading */
+	if (!mod)
+		mod = rec->arch.mod;
+	else
+		rec->arch.mod = mod;
+#endif
+
+	old = ftrace_call_replace(ip, aaddr,
+				  !IS_ENABLED(CONFIG_ARM_MODULE_PLTS) || !mod);
+#ifdef CONFIG_ARM_MODULE_PLTS
+	if (!old && mod) {
+		aaddr = get_module_plt(mod, ip, aaddr);
+		old = ftrace_call_replace(ip, aaddr, true);
+	}
+#endif
+
+	new = ftrace_nop_replace(rec);
+	/*
+	 * Locations in .init.text may call __gnu_mcount_mc via a linker
+	 * emitted veneer if they are too far away from its implementation, and
+	 * so validation may fail spuriously in such cases. Let's work around
+	 * this by omitting those from validation.
+	 */
+	ret = ftrace_modify_code(ip, old, new, !is_kernel_inittext(ip));
+
+	return ret;
+}
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+asmlinkage
+void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
+			   unsigned long frame_pointer,
+			   unsigned long stack_pointer)
+{
+	unsigned long return_hooker = (unsigned long) &return_to_handler;
+	unsigned long old;
+
+	if (unlikely(atomic_read(&current->tracing_graph_pause)))
+		return;
+
+	if (IS_ENABLED(CONFIG_UNWINDER_FRAME_POINTER)) {
+		/* FP points one word below parent's top of stack */
+		frame_pointer += 4;
+	} else {
+		struct stackframe frame = {
+			.fp = frame_pointer,
+			.sp = stack_pointer,
+			.lr = self_addr,
+			.pc = self_addr,
+		};
+		if (unwind_frame(&frame) < 0)
+			return;
+		if (frame.lr != self_addr)
+			parent = frame.lr_addr;
+		frame_pointer = frame.sp;
+	}
+
+	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 = arm_gen_nop();
+	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
+
+
+	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 */