Multi-console: Deprecate the `finish_console_register` macro

The `finish_console_register` macro is used by the multi console
framework to register the `console_t` driver callbacks. It relied
on weak references to the `ldr` instruction to populate 0 to the
callback in case the driver has not defined the appropriate
function. Use of `ldr` instruction to load absolute address to a
reference makes the binary position dependant. These instructions
should be replaced with adrp/adr instruction for position independant
executable(PIE). But adrp/adr instructions don't work well with weak
references as described in GNU ld bugzilla issue 22589.

This patch defines a new version of `finish_console_register` macro
which can spcify which driver callbacks are valid and deprecates the
old one. If any of the argument is not specified, then the macro
populates 0 for that callback. Hence the functionality of the previous
deprecated macro is preserved. The USE_FINISH_CONSOLE_REG_2 define
is used to select the new variant of...

drivers/arm/pl011/aarch32/pl011_console.S

@@ -6,6 +6,7 @@
 #include <arch.h>
 #include <asm_macros.S>
 #include <assert_macros.S>
+#define USE_FINISH_CONSOLE_REG_2
 #include <console_macros.S>
 #include <pl011.h>
 
@@ -116,7 +117,7 @@ func console_pl011_register
 
 	mov	r0, r4
 	pop	{r4, lr}
-	finish_console_register pl011
+	finish_console_register pl011 putc=1, getc=1, flush=1
 
 register_fail:
 	pop	{r4, pc}

drivers/arm/pl011/aarch64/pl011_console.S

@@ -6,6 +6,7 @@
 #include <arch.h>
 #include <asm_macros.S>
 #include <assert_macros.S>
+#define USE_FINISH_CONSOLE_REG_2
 #include <console_macros.S>
 #include <pl011.h>
 
@@ -110,7 +111,7 @@ func console_pl011_register
 
 	mov	x0, x6
 	mov	x30, x7
-	finish_console_register pl011
+	finish_console_register pl011 putc=1, getc=1, flush=1
 
 register_fail:
 	ret	x7

drivers/cadence/uart/aarch64/cdns_console.S

@@ -7,6 +7,8 @@
 #include <asm_macros.S>
 #include <assert_macros.S>
 #include <cadence/cdns_uart.h>
+#define USE_FINISH_CONSOLE_REG_2
+#include <console_macros.S>
 
 	/*
 	 * "core" functions are low-level implementations that don't require
@@ -77,7 +79,7 @@ func console_cdns_register
 
 	mov	x0, x6
 	mov	x30, v7
-	finish_console_register cdns
+	finish_console_register cdns putc=1, getc=1, flush=1
 
 register_fail:
 	ret	x7

drivers/console/aarch64/skeleton_console.S

@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 #include <asm_macros.S>
+#define USE_FINISH_CONSOLE_REG_2
 #include <console_macros.S>
 
 	/*
@@ -60,8 +61,12 @@ func console_xxx_register
 	 * Keep console_t pointer in x0 for later.
 	 */
 
-	/* Macro to finish up registration and return (needs valid x0 + x30). */
-	finish_console_register xxx
+	/*
+	 * Macro to finish up registration and return (needs valid x0 + x30).
+	 * If any of the argument is unspecified, then the corresponding
+	 * entry in console_t is set to 0.
+	 */
+	finish_console_register xxx putc=1, getc=1, flush=1
 
 	/* Jump here if hardware init fails or parameters are invalid. */
 register_fail:

drivers/coreboot/cbmem_console/aarch64/cbmem_console.S

@@ -6,6 +6,7 @@
 
 #include <asm_macros.S>
 #include <cbmem_console.h>
+#define USE_FINISH_CONSOLE_REG_2
 #include <console_macros.S>
 
 /*
@@ -39,7 +40,7 @@ func console_cbmc_register
 	ldr	w2, [x0]
 	str	w2, [x1, #CONSOLE_T_CBMC_SIZE]
 	mov	x0, x1
-	finish_console_register cbmc
+	finish_console_register cbmc putc=1, flush=1
 endfunc console_cbmc_register
 
 	/* -----------------------------------------------

drivers/ti/uart/aarch64/16550_console.S

@@ -7,6 +7,7 @@
 #include <arch.h>
 #include <asm_macros.S>
 #include <assert_macros.S>
+#define USE_FINISH_CONSOLE_REG_2
 #include <console_macros.S>
 #include <uart_16550.h>
 
@@ -112,7 +113,7 @@ func console_16550_register
 
 	mov	x0, x6
 	mov	x30, x7
-	finish_console_register 16550
+	finish_console_register 16550 putc=1, getc=1, flush=1
 
 register_fail:
 	ret	x7

include/common/aarch32/console_macros.S

@@ -17,6 +17,14 @@
  * with a tail call that will include return to the caller.
  * REQUIRES console_t pointer in x0 and a valid return address in x30.
  */
+/*
+ * The USE_FINISH_CONSOLE_REG_2 guard is introduced to allow selection between
+ * the 2 variants of the finish_console_register macro and will be removed
+ * once the deprecated variant is removed.
+ */
+#ifndef USE_FINISH_CONSOLE_REG_2
+#if !ERROR_DEPRECATED
+	/* This version of the macro is deprecated. Use the new version */
 	.macro	finish_console_register _driver
 	/*
 	 * Add these weak definitions so we will automatically write a 0 if the
@@ -39,5 +47,38 @@
 	str	r1, [r0, #CONSOLE_T_FLAGS]
 	b	console_register
 	.endm
+#endif /* ERROR_DEPRECATED */
+#else /* USE_FINISH_CONSOLE_REG_2 */
+	/* The new version of the macro not using weak references */
+	.macro	finish_console_register _driver, putc=0, getc=0, flush=0
+	/*
+	 * If any of the callback is not specified or set as 0, then the
+	 * corresponding callback entry in console_t is set to 0.
+	 */
+	.ifne \putc
+	  ldr	r1, =console_\_driver\()_putc
+	.else
+	  mov	r1, #0
+	.endif
+	str	r1, [r0, #CONSOLE_T_PUTC]
+
+	.ifne \getc
+	  ldr	r1, =console_\_driver\()_getc
+	.else
+	  mov	r1, #0
+	.endif
+	str	r1, [r0, #CONSOLE_T_GETC]
+
+	.ifne \flush
+	  ldr	r1, =console_\_driver\()_flush
+	.else
+	  mov	r1, #0
+	.endif
+	str	r1, [r0, #CONSOLE_T_FLUSH]
 
+	mov	r1, #(CONSOLE_FLAG_BOOT | CONSOLE_FLAG_CRASH)
+	str	r1, [r0, #CONSOLE_T_FLAGS]
+	b	console_register
+	.endm
+#endif /* USE_FINISH_CONSOLE_REG_2 */
 #endif /* __CONSOLE_MACROS_S__ */

include/common/aarch64/console_macros.S

 /*
- * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -17,6 +17,14 @@
  * with a tail call that will include return to the caller.
  * REQUIRES console_t pointer in x0 and a valid return address in x30.
  */
+/*
+ * The USE_FINISH_CONSOLE_REG_2 guard is introduced to allow selection between
+ * the 2 variants of the finish_console_register macro and will be removed
+ * once the deprecated variant is removed.
+ */
+#ifndef USE_FINISH_CONSOLE_REG_2
+#if !ERROR_DEPRECATED
+	/* This version of the macro is deprecated. Use the new version */
 	.macro	finish_console_register _driver
 	/*
 	 * Add these weak definitions so we will automatically write a 0 if the
@@ -39,5 +47,41 @@
 	str	x1, [x0, #CONSOLE_T_FLAGS]
 	b	console_register
 	.endm
+#endif /* ERROR_DEPRECATED */
+#else /* USE_FINISH_CONSOLE_REG_2 */
+	/* The new version of the macro not using weak references */
+	.macro	finish_console_register _driver, putc=0, getc=0, flush=0
+	/*
+	 * If any of the callback is not specified or set as 0, then the
+	 * corresponding callback entry in console_t is set to 0.
+	 */
+	.ifne \putc
+	  adrp	x1, console_\_driver\()_putc
+	  add	x1, x1, :lo12:console_\_driver\()_putc
+	  str	x1, [x0, #CONSOLE_T_PUTC]
+	.else
+	  str	xzr, [x0, #CONSOLE_T_PUTC]
+	.endif
+
+	.ifne \getc
+	  adrp	x1, console_\_driver\()_getc
+	  add	x1, x1, :lo12:console_\_driver\()_getc
+	  str	x1, [x0, #CONSOLE_T_GETC]
+	.else
+	  str	xzr, [x0, #CONSOLE_T_GETC]
+	.endif
 
+	.ifne \flush
+	  adrp	x1, console_\_driver\()_flush
+	  add	x1, x1, :lo12:console_\_driver\()_flush
+	  str	x1, [x0, #CONSOLE_T_FLUSH]
+	.else
+	  str	xzr, [x0, #CONSOLE_T_FLUSH]
+	.endif
+
+	mov	x1, #(CONSOLE_FLAG_BOOT | CONSOLE_FLAG_CRASH)
+	str	x1, [x0, #CONSOLE_T_FLAGS]
+	b	console_register
+	.endm
+#endif /* USE_FINISH_CONSOLE_REG_2 */
 #endif /* __CONSOLE_MACROS_S__ */

plat/imx/common/lpuart_console.S

@@ -6,6 +6,7 @@
 
 #include <arch.h>
 #include <asm_macros.S>
+#define USE_FINISH_CONSOLE_REG_2
 #include <console_macros.S>
 #include <assert_macros.S>
 #include "imx8_lpuart.h"
@@ -26,7 +27,7 @@ func console_lpuart_register
 
 	mov	x0, x6
 	mov	x30, x7
-	finish_console_register lpuart
+	finish_console_register lpuart putc=1, getc=1
 
 register_fail:
 	ret	x7

plat/layerscape/common/aarch64/ls_console.S

@@ -6,6 +6,7 @@
 
 #include <arch.h>
 #include <asm_macros.S>
+#define USE_FINISH_CONSOLE_REG_2
 #include <console_macros.S>
 #include <assert_macros.S>
 #include "ls_16550.h"
@@ -106,7 +107,7 @@ func console_ls_16550_register
 
 	mov	x0, x6
 	mov	x30, x7
-	finish_console_register ls_16550
+	finish_console_register ls_16550 putc=1, getc=1, flush=1
 
 register_fail:
 	ret	x7