compiler.h: add __weak macro

Instead of writing out '__attribute__((weak))' use a shorter form.

Change-Id: If418a1d55052780077febd2d8f2089021f414b91
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/25767
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Justin TerAvest <teravest@chromium.org>

src/security/vboot/bootmode.c

@@ -17,6 +17,7 @@
 #include <bootmode.h>
 #include <bootstate.h>
 #include <cbmem.h>
+#include <compiler.h>
 #include <rules.h>
 #include <string.h>
 #include <vb2_api.h>
@@ -141,18 +142,18 @@ int vboot_recovery_mode_enabled(void)
 	return !!vboot_check_recovery_request();
 }
 
-int __attribute__((weak)) clear_recovery_mode_switch(void)
+int __weak clear_recovery_mode_switch(void)
 {
 	// Weak implementation. Nothing to do.
 	return 0;
 }
 
-void __attribute__((weak)) log_recovery_mode_switch(void)
+void __weak log_recovery_mode_switch(void)
 {
 	// Weak implementation. Nothing to do.
 }
 
-int __attribute__((weak)) get_recovery_mode_retrain_switch(void)
+int __weak get_recovery_mode_retrain_switch(void)
 {
 	return 0;
 }
@@ -175,12 +176,12 @@ int vboot_developer_mode_enabled(void)
  * TODO: Create flash protection interface which implements get_write_protect_state.
  * get_recovery_mode_switch should be implemented as default function.
  */
-int __attribute__((weak)) get_write_protect_state(void)
+int __weak get_write_protect_state(void)
 {
 	return 0;
 }
 
-int __attribute__((weak)) get_recovery_mode_switch(void)
+int __weak get_recovery_mode_switch(void)
 {
 	return 0;
 }

src/security/vboot/vboot_common.c

@@ -16,6 +16,7 @@
 #include <boot/coreboot_tables.h>
 #include <boot_device.h>
 #include <cbmem.h>
+#include <compiler.h>
 #include <console/cbmem_console.h>
 #include <console/console.h>
 #include <fmap.h>
@@ -101,7 +102,7 @@ int vboot_handoff_get_recovery_reason(void)
 }
 
 /* ============================ VBOOT REBOOT ============================== */
-void __attribute__((weak)) vboot_platform_prepare_reboot(void)
+void __weak vboot_platform_prepare_reboot(void)
 {
 }
 

src/security/vboot/vboot_logic.c

@@ -17,6 +17,7 @@
 #include <arch/exception.h>
 #include <assert.h>
 #include <bootmode.h>
+#include <compiler.h>
 #include <console/console.h>
 #include <console/vtxprintf.h>
 #include <delay.h>
@@ -95,21 +96,21 @@ int vb2ex_read_resource(struct vb2_context *ctx,
 }
 
 /* No-op stubs that can be overridden by SoCs with hardware crypto support. */
-__attribute__((weak))
+__weak
 int vb2ex_hwcrypto_digest_init(enum vb2_hash_algorithm hash_alg,
 			       uint32_t data_size)
 {
 	return VB2_ERROR_EX_HWCRYPTO_UNSUPPORTED;
 }
 
-__attribute__((weak))
+__weak
 int vb2ex_hwcrypto_digest_extend(const uint8_t *buf, uint32_t size)
 {
 	BUG();	/* Should never get called if init() returned an error. */
 	return VB2_ERROR_UNKNOWN;
 }
 
-__attribute__((weak))
+__weak
 int vb2ex_hwcrypto_digest_finalize(uint8_t *digest, uint32_t digest_size)
 {
 	BUG();	/* Should never get called if init() returned an error. */

src/security/vboot/verstage.c

@@ -15,11 +15,12 @@
 
 #include <arch/exception.h>
 #include <arch/hlt.h>
+#include <compiler.h>
 #include <console/console.h>
 #include <program_loading.h>
 #include <security/vboot/vboot_common.h>
 
-void __attribute__((weak)) verstage_mainboard_init(void)
+void __weak verstage_mainboard_init(void)
 {
 	/* Default empty implementation. */
 }