Merge tag 'objtool-core-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool updates from Ingo Molnar:
 "There are a lot of objtool changes in this cycle, all across the map:

   - Speed up objtool significantly, especially when there are large
     number of sections

   - Improve objtool's understanding of special instructions such as
     IRET, to reduce the number of annotations required

   - Implement 'noinstr' validation

   - Do baby steps for non-x86 objtool use

   - Simplify/fix retpoline decoding

   - Add vmlinux validation

   - Improve documentation

   - Fix various bugs and apply smaller cleanups"

* tag 'objtool-core-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (54 commits)
  objtool: Enable compilation of objtool for all architectures
  objtool: Move struct objtool_file into arch-independent header
  objtool: Exit successfully when requesting help
  objtool: Add check_kcov_mode() to the uaccess safelist
  samples/ftrace: Fix asm function ELF annotations
  objtool: optimize add_dead_ends for split sections
  objtool: use gelf_getsymshndx to handle >64k sections
  objtool: Allow no-op CFI ops in alternatives
  x86/retpoline: Fix retpoline unwind
  x86: Change {JMP,CALL}_NOSPEC argument
  x86: Simplify retpoline declaration
  x86/speculation: Change FILL_RETURN_BUFFER to work with objtool
  objtool: Add support for intra-function calls
  objtool: Move the IRET hack into the arch decoder
  objtool: Remove INSN_STACK
  objtool: Make handle_insn_ops() unconditional
  objtool: Rework allocating stack_ops on decode
  objtool: UNWIND_HINT_RET_OFFSET should not check registers
  objtool: is_fentry_call() crashes if call has no destination
  x86,smap: Fix smap_{save,restore}() alternatives
  ...

3 files changed, 33 insertions, 27 deletions

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index b0e641793be4..c84d28e90a58 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -282,7 +282,8 @@ static inline void tramp_free(void *tramp) { }
 
 /* Defined as markers to the end of the ftrace default trampolines */
 extern void ftrace_regs_caller_end(void);
-extern void ftrace_epilogue(void);
+extern void ftrace_regs_caller_ret(void);
+extern void ftrace_caller_end(void);
 extern void ftrace_caller_op_ptr(void);
 extern void ftrace_regs_caller_op_ptr(void);
 
@@ -334,7 +335,7 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
 		call_offset = (unsigned long)ftrace_regs_call;
 	} else {
 		start_offset = (unsigned long)ftrace_caller;
-		end_offset = (unsigned long)ftrace_epilogue;
+		end_offset = (unsigned long)ftrace_caller_end;
 		op_offset = (unsigned long)ftrace_caller_op_ptr;
 		call_offset = (unsigned long)ftrace_call;
 	}
@@ -366,6 +367,13 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
 	if (WARN_ON(ret < 0))
 		goto fail;
 
+	if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) {
+		ip = trampoline + (ftrace_regs_caller_ret - ftrace_regs_caller);
+		ret = probe_kernel_read(ip, (void *)retq, RET_SIZE);
+		if (WARN_ON(ret < 0))
+			goto fail;
+	}
+
 	/*
 	 * The address of the ftrace_ops that is used for this trampoline
 	 * is stored at the end of the trampoline. This will be used to
@@ -433,7 +441,7 @@ void set_ftrace_ops_ro(void)
 			end_offset = (unsigned long)ftrace_regs_caller_end;
 		} else {
 			start_offset = (unsigned long)ftrace_caller;
-			end_offset = (unsigned long)ftrace_epilogue;
+			end_offset = (unsigned long)ftrace_caller_end;
 		}
 		size = end_offset - start_offset;
 		size = size + RET_SIZE + sizeof(void *);
diff --git a/arch/x86/kernel/ftrace_32.S b/arch/x86/kernel/ftrace_32.S
index e8a9f8370112..e405fe1a8bf4 100644
--- a/arch/x86/kernel/ftrace_32.S
+++ b/arch/x86/kernel/ftrace_32.S
@@ -189,5 +189,5 @@ return_to_handler:
 	movl	%eax, %ecx
 	popl	%edx
 	popl	%eax
-	JMP_NOSPEC %ecx
+	JMP_NOSPEC ecx
 #endif
diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S
index 369e61faacfe..aa5d28aeb31e 100644
--- a/arch/x86/kernel/ftrace_64.S
+++ b/arch/x86/kernel/ftrace_64.S
@@ -23,7 +23,7 @@
 #endif /* CONFIG_FRAME_POINTER */
 
 /* Size of stack used to save mcount regs in save_mcount_regs */
-#define MCOUNT_REG_SIZE		(SS+8 + MCOUNT_FRAME_SIZE)
+#define MCOUNT_REG_SIZE		(FRAME_SIZE + MCOUNT_FRAME_SIZE)
 
 /*
  * gcc -pg option adds a call to 'mcount' in most functions.
@@ -77,7 +77,7 @@
 	/*
 	 * We add enough stack to save all regs.
 	 */
-	subq $(MCOUNT_REG_SIZE - MCOUNT_FRAME_SIZE), %rsp
+	subq $(FRAME_SIZE), %rsp
 	movq %rax, RAX(%rsp)
 	movq %rcx, RCX(%rsp)
 	movq %rdx, RDX(%rsp)
@@ -157,8 +157,12 @@ SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL)
 	 * think twice before adding any new code or changing the
 	 * layout here.
 	 */
-SYM_INNER_LABEL(ftrace_epilogue, SYM_L_GLOBAL)
+SYM_INNER_LABEL(ftrace_caller_end, SYM_L_GLOBAL)
 
+	jmp ftrace_epilogue
+SYM_FUNC_END(ftrace_caller);
+
+SYM_FUNC_START(ftrace_epilogue)
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 SYM_INNER_LABEL(ftrace_graph_call, SYM_L_GLOBAL)
 	jmp ftrace_stub
@@ -170,14 +174,12 @@ SYM_INNER_LABEL(ftrace_graph_call, SYM_L_GLOBAL)
  */
 SYM_INNER_LABEL_ALIGN(ftrace_stub, SYM_L_WEAK)
 	retq
-SYM_FUNC_END(ftrace_caller)
+SYM_FUNC_END(ftrace_epilogue)
 
 SYM_FUNC_START(ftrace_regs_caller)
 	/* Save the current flags before any operations that can change them */
 	pushfq
 
-	UNWIND_HINT_SAVE
-
 	/* added 8 bytes to save flags */
 	save_mcount_regs 8
 	/* save_mcount_regs fills in first two parameters */
@@ -233,10 +235,13 @@ SYM_INNER_LABEL(ftrace_regs_call, SYM_L_GLOBAL)
 	movq ORIG_RAX(%rsp), %rax
 	movq %rax, MCOUNT_REG_SIZE-8(%rsp)
 
-	/* If ORIG_RAX is anything but zero, make this a call to that */
+	/*
+	 * If ORIG_RAX is anything but zero, make this a call to that.
+	 * See arch_ftrace_set_direct_caller().
+	 */
 	movq ORIG_RAX(%rsp), %rax
-	cmpq	$0, %rax
-	je	1f
+	testq	%rax, %rax
+	jz	1f
 
 	/* Swap the flags with orig_rax */
 	movq MCOUNT_REG_SIZE(%rsp), %rdi
@@ -244,20 +249,14 @@ SYM_INNER_LABEL(ftrace_regs_call, SYM_L_GLOBAL)
 	movq %rax, MCOUNT_REG_SIZE(%rsp)
 
 	restore_mcount_regs 8
+	/* Restore flags */
+	popfq
 
-	jmp	2f
+SYM_INNER_LABEL(ftrace_regs_caller_ret, SYM_L_GLOBAL);
+	UNWIND_HINT_RET_OFFSET
+	jmp	ftrace_epilogue
 
 1:	restore_mcount_regs
-
-
-2:
-	/*
-	 * The stack layout is nondetermistic here, depending on which path was
-	 * taken.  This confuses objtool and ORC, rightfully so.  For now,
-	 * pretend the stack always looks like the non-direct case.
-	 */
-	UNWIND_HINT_RESTORE
-
 	/* Restore flags */
 	popfq
 
@@ -268,7 +267,6 @@ SYM_INNER_LABEL(ftrace_regs_call, SYM_L_GLOBAL)
 	 * to the return.
 	 */
 SYM_INNER_LABEL(ftrace_regs_caller_end, SYM_L_GLOBAL)
-
 	jmp ftrace_epilogue
 
 SYM_FUNC_END(ftrace_regs_caller)
@@ -303,7 +301,7 @@ trace:
 	 * function tracing is enabled.
 	 */
 	movq ftrace_trace_function, %r8
-	CALL_NOSPEC %r8
+	CALL_NOSPEC r8
 	restore_mcount_regs
 
 	jmp fgraph_trace
@@ -340,6 +338,6 @@ SYM_CODE_START(return_to_handler)
 	movq 8(%rsp), %rdx
 	movq (%rsp), %rax
 	addq $24, %rsp
-	JMP_NOSPEC %rdi
+	JMP_NOSPEC rdi
 SYM_CODE_END(return_to_handler)
 #endif