1 files changed, 113 insertions, 103 deletions

diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index 5617932a83df..845acf9ce21e 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -22,11 +22,24 @@
 #include <asm/ftrace.h>
 #include <asm/insn.h>
 #include <asm/set_memory.h>
+#include <asm/stacktrace.h>
+#include <asm/text-patching.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		0xf85deb04	/* pop.w {lr} */
+#define	NOP		0xf10d0d04	/* add.w sp, sp, #4 */
 #else
-#define	NOP		0xe8bd4000	/* pop {lr} */
+#define	NOP		0xe28dd004	/* add   sp, sp, #4 */
 #endif
 
 #ifdef CONFIG_DYNAMIC_FTRACE
@@ -35,9 +48,7 @@ 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;
 }
@@ -47,58 +58,41 @@ 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)
+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)
 {
-	return 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;
 }
-#endif
 
-int ftrace_arch_code_modify_prepare(void)
+void ftrace_arch_code_modify_prepare(void)
 {
-	set_all_modules_text_rw();
-	return 0;
 }
 
-int ftrace_arch_code_modify_post_process(void)
+void 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)
+static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr,
+					 bool warn)
 {
-	return arm_gen_branch_link(pc, addr);
+	return arm_gen_branch_link(pc, addr, warn);
 }
 
 static int ftrace_modify_code(unsigned long pc, unsigned long old,
@@ -106,26 +100,21 @@ static int ftrace_modify_code(unsigned long pc, unsigned long old,
 {
 	unsigned long replaced;
 
-	if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
+	if (IS_ENABLED(CONFIG_THUMB2_KERNEL))
 		old = __opcode_to_mem_thumb32(old);
-		new = __opcode_to_mem_thumb32(new);
-	} else {
+	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))
+		if (copy_from_kernel_nofault(&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);
+	__patch_text((void *)pc, new);
 
 	return 0;
 }
@@ -137,23 +126,14 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
 	int ret;
 
 	pc = (unsigned long)&ftrace_call;
-	new = ftrace_call_replace(pc, (unsigned long)func);
+	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);
-
-		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);
+		new = ftrace_call_replace(pc, (unsigned long)func, true);
 
 		ret = ftrace_modify_code(pc, 0, new, false);
 	}
@@ -166,10 +146,22 @@ 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, adjust_address(rec, addr));
+	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);
 }
@@ -182,9 +174,9 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
 	unsigned long new, old;
 	unsigned long ip = rec->ip;
 
-	old = ftrace_call_replace(ip, adjust_address(rec, old_addr));
+	old = ftrace_call_replace(ip, adjust_address(rec, old_addr), true);
 
-	new = ftrace_call_replace(ip, adjust_address(rec, addr));
+	new = ftrace_call_replace(ip, adjust_address(rec, addr), true);
 
 	return ftrace_modify_code(rec->ip, old, new, true);
 }
@@ -194,64 +186,89 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
 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;
 
-	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;
+#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, adjust_address(rec, addr));
-		new = ftrace_nop_replace(rec);
-		ret = ftrace_modify_code(ip, old, new, true);
+	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
 
-	return ret;
-}
+	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));
 
-int __init ftrace_dyn_arch_init(void)
-{
-	return 0;
+	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 frame_pointer,
+			   unsigned long stack_pointer)
 {
 	unsigned long return_hooker = (unsigned long) &return_to_handler;
-	struct ftrace_graph_ent trace;
 	unsigned long old;
-	int err;
 
 	if (unlikely(atomic_read(&current->tracing_graph_pause)))
+err_out:
 		return;
 
+	if (IS_ENABLED(CONFIG_UNWINDER_FRAME_POINTER)) {
+		/*
+		 * Usually, the stack frames are contiguous in memory but cases
+		 * have been observed where the next stack frame does not live
+		 * at 'frame_pointer + 4' as this code used to assume.
+		 *
+		 * Instead, dereference the field in the stack frame that
+		 * stores the SP of the calling frame: to avoid unbounded
+		 * recursion, this cannot involve any ftrace instrumented
+		 * functions, so use the __get_kernel_nofault() primitive
+		 * directly.
+		 */
+		__get_kernel_nofault(&frame_pointer,
+				     (unsigned long *)(frame_pointer - 8),
+				     unsigned long, err_out);
+	} 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;
 
-	trace.func = self_addr;
-	trace.depth = current->curr_ret_stack + 1;
-
-	/* Only trace if the calling function expects to */
-	if (!ftrace_graph_entry(&trace)) {
-		*parent = old;
-		return;
-	}
-
-	err = ftrace_push_return_trace(old, self_addr, &trace.depth,
-				       frame_pointer, NULL);
-	if (err == -EBUSY) {
+	if (function_graph_enter(old, self_addr, frame_pointer, NULL))
 		*parent = old;
-		return;
-	}
 }
 
 #ifdef CONFIG_DYNAMIC_FTRACE
@@ -267,7 +284,7 @@ static int __ftrace_modify_caller(unsigned long *callsite,
 	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 nop = arm_gen_nop();
 	unsigned long old = enable ? nop : branch;
 	unsigned long new = enable ? branch : nop;
 
@@ -290,13 +307,6 @@ static int ftrace_modify_graph_caller(bool enable)
 #endif
 
 
-#ifdef CONFIG_OLD_MCOUNT
-	if (!ret)
-		ret = __ftrace_modify_caller(&ftrace_graph_call_old,
-					     ftrace_graph_caller_old,
-					     enable);
-#endif
-
 	return ret;
 }