arm64: entry-ftrace.S: avoid open-coded {adr,ldr}_l

mrutland-arm · wildea01 · commit 829d2bd13392 · 2017-01-17T17:41:19.000Z
Some places in the kernel open-code sequences using ADRP for a symbol
another instruction using a :lo12: relocation for that same symbol.
These sequences are easy to get wrong, and more painful to read than is
necessary. For these reasons, it is preferable to use the
{adr,ldr,str}_l macros for these cases.

This patch makes use of these in entry-ftrace.S, removing open-coded
sequences using adrp. This results in a minor code change, since a
temporary register is not used when generating the address for some
symbols, but this is fine, as the value of the temporary register is not
used elsewhere.

Signed-off-by: Mark Rutland &lt;mark.rutland@arm.com&gt;
Reviewed-by: Ard Biesheuvel &lt;ard.biesheuvel@linaro.org&gt;
Cc: AKASHI Takahiro &lt;takahiro.akashi@linaro.org&gt;
Cc: Ard Biesheuvel &lt;ard.biesheuvel@linaro.org&gt;
Cc: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Cc: Will Deacon &lt;will.deacon@arm.com&gt;
Signed-off-by: Will Deacon &lt;will.deacon@arm.com&gt;
diff --git a/arch/arm64/kernel/entry-ftrace.S b/arch/arm64/kernel/entry-ftrace.S
@@ -98,8 +98,7 @@
 ENTRY(_mcount)
 	mcount_enter
 
-	adrp	x0, ftrace_trace_function
-	ldr	x2, [x0, #:lo12:ftrace_trace_function]
+	ldr_l	x2, ftrace_trace_function
 	adr	x0, ftrace_stub
 	cmp	x0, x2			// if (ftrace_trace_function
 	b.eq	skip_ftrace_call	//     != ftrace_stub) {
@@ -115,15 +114,12 @@ skip_ftrace_call:			//   return;
 	mcount_exit			//   return;
 					// }
 skip_ftrace_call:
-	adrp	x1, ftrace_graph_return
-	ldr	x2, [x1, #:lo12:ftrace_graph_return]
+	ldr_l	x2, ftrace_graph_return
 	cmp	x0, x2			//   if ((ftrace_graph_return
 	b.ne	ftrace_graph_caller	//        != ftrace_stub)
 
-	adrp	x1, ftrace_graph_entry	//     || (ftrace_graph_entry
-	adrp	x0, ftrace_graph_entry_stub //     != ftrace_graph_entry_stub))
-	ldr	x2, [x1, #:lo12:ftrace_graph_entry]
-	add	x0, x0, #:lo12:ftrace_graph_entry_stub
+	ldr_l	x2, ftrace_graph_entry	//     || (ftrace_graph_entry
+	adr_l	x0, ftrace_graph_entry_stub //     != ftrace_graph_entry_stub))
 	cmp	x0, x2
 	b.ne	ftrace_graph_caller	//     ftrace_graph_caller();
 
