ARM: i.MX8M: atf: mark ATF start functions as __noreturn

The early exit in imx8m_atf_load_bl31 doesn't serve any real purpose.
If a too big TF-A ends up being loaded we shouldn't return, but
just panic outright, so the user fixes their barebox build.

Change the WARN_ON to a BUG_ON() and then mark all callers of this
function as __noreturn to document their purpose and to guide
optimization.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.barebox.org/20220816073056.45694-1-a.fatoum@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

3 files changed, 22 insertions, 23 deletions

diff --git a/arch/arm/mach-imx/atf.c b/arch/arm/mach-imx/atf.c
index a4c6582830..df23dbfc0e 100644
--- a/arch/arm/mach-imx/atf.c
+++ b/arch/arm/mach-imx/atf.c
@@ -35,12 +35,11 @@
  *
  */
 
-static void imx8m_atf_load_bl31(const void *fw, size_t fw_size, void *atf_dest)
+static __noreturn void imx8m_atf_load_bl31(const void *fw, size_t fw_size, void *atf_dest)
 {
 	void __noreturn (*bl31)(void) = atf_dest;
 
-	if (WARN_ON(fw_size > MX8M_ATF_BL31_SIZE_LIMIT))
-		return;
+	BUG_ON(fw_size > MX8M_ATF_BL31_SIZE_LIMIT);
 
 	memcpy(bl31, fw, fw_size);
 
@@ -48,29 +47,30 @@ static void imx8m_atf_load_bl31(const void *fw, size_t fw_size, void *atf_dest)
 		     "r" (atf_dest - 16) :
 		     "cc");
 	bl31();
+	__builtin_unreachable();
 }
 
-void imx8mm_atf_load_bl31(const void *fw, size_t fw_size)
+__noreturn void imx8mm_atf_load_bl31(const void *fw, size_t fw_size)
 {
 	imx8m_atf_load_bl31(fw, fw_size, (void *)MX8MM_ATF_BL31_BASE_ADDR);
 }
 
-void imx8mn_atf_load_bl31(const void *fw, size_t fw_size)
+__noreturn void imx8mn_atf_load_bl31(const void *fw, size_t fw_size)
 {
 	imx8m_atf_load_bl31(fw, fw_size, (void *)MX8MN_ATF_BL31_BASE_ADDR);
 }
 
-void imx8mp_atf_load_bl31(const void *fw, size_t fw_size)
+__noreturn void imx8mp_atf_load_bl31(const void *fw, size_t fw_size)
 {
 	imx8m_atf_load_bl31(fw, fw_size, (void *)MX8MP_ATF_BL31_BASE_ADDR);
 }
 
-void imx8mq_atf_load_bl31(const void *fw, size_t fw_size)
+__noreturn void imx8mq_atf_load_bl31(const void *fw, size_t fw_size)
 {
 	imx8m_atf_load_bl31(fw, fw_size, (void *)MX8MQ_ATF_BL31_BASE_ADDR);
 }
 
-void imx8mm_load_and_start_image_via_tfa(void)
+__noreturn void imx8mm_load_and_start_image_via_tfa(void)
 {
 	size_t bl31_size;
 	const u8 *bl31;
@@ -126,11 +126,9 @@ void imx8mm_load_and_start_image_via_tfa(void)
 	get_builtin_firmware(imx8mm_bl31_bin, &bl31, &bl31_size);
 
 	imx8mm_atf_load_bl31(bl31, bl31_size);
-
-	/* not reached */
 }
 
-void imx8mp_load_and_start_image_via_tfa(void)
+__noreturn void imx8mp_load_and_start_image_via_tfa(void)
 {
 	size_t bl31_size;
 	const u8 *bl31;
@@ -165,11 +163,9 @@ void imx8mp_load_and_start_image_via_tfa(void)
 	get_builtin_firmware(imx8mp_bl31_bin, &bl31, &bl31_size);
 
 	imx8mp_atf_load_bl31(bl31, bl31_size);
-
-	/* not reached */
 }
 
-void imx8mn_load_and_start_image_via_tfa(void)
+__noreturn void imx8mn_load_and_start_image_via_tfa(void)
 {
 	size_t bl31_size;
 	const u8 *bl31;
@@ -204,6 +200,4 @@ void imx8mn_load_and_start_image_via_tfa(void)
 	get_builtin_firmware(imx8mn_bl31_bin, &bl31, &bl31_size);
 
 	imx8mn_atf_load_bl31(bl31, bl31_size);
-
-	/* not reached */
 }
diff --git a/arch/arm/mach-imx/include/mach/atf.h b/arch/arm/mach-imx/include/mach/atf.h
index bc400ddbad..ca54bb5fbf 100644
--- a/arch/arm/mach-imx/include/mach/atf.h
+++ b/arch/arm/mach-imx/include/mach/atf.h
@@ -4,6 +4,8 @@
 #define __IMX_ATF_H__
 
 #include <linux/sizes.h>
+#include <linux/compiler.h>
+#include <linux/types.h>
 #include <asm/system.h>
 
 #define MX8M_ATF_BL31_SIZE_LIMIT	SZ_64K
@@ -16,9 +18,9 @@
 #define MX8MM_ATF_BL33_BASE_ADDR	MX8M_ATF_BL33_BASE_ADDR
 #define MX8MQ_ATF_BL33_BASE_ADDR	MX8M_ATF_BL33_BASE_ADDR
 
-void imx8mm_atf_load_bl31(const void *fw, size_t fw_size);
-void imx8mn_atf_load_bl31(const void *fw, size_t fw_size);
-void imx8mp_atf_load_bl31(const void *fw, size_t fw_size);
-void imx8mq_atf_load_bl31(const void *fw, size_t fw_size);
+void __noreturn imx8mm_atf_load_bl31(const void *fw, size_t fw_size);
+void __noreturn imx8mn_atf_load_bl31(const void *fw, size_t fw_size);
+void __noreturn imx8mp_atf_load_bl31(const void *fw, size_t fw_size);
+void __noreturn imx8mq_atf_load_bl31(const void *fw, size_t fw_size);
 
 #endif
diff --git a/arch/arm/mach-imx/include/mach/xload.h b/arch/arm/mach-imx/include/mach/xload.h
index 3090c9c83b..fe43d25026 100644
--- a/arch/arm/mach-imx/include/mach/xload.h
+++ b/arch/arm/mach-imx/include/mach/xload.h
@@ -3,6 +3,9 @@
 #ifndef __MACH_XLOAD_H
 #define __MACH_XLOAD_H
 
+#include <linux/compiler.h>
+#include <linux/types.h>
+
 int imx53_nand_start_image(void);
 int imx6_spi_load_image(int instance, unsigned int flash_offset, void *buf, int len);
 int imx6_spi_start_image(int instance);
@@ -13,9 +16,9 @@ int imx8m_esdhc_load_image(int instance, bool start);
 int imx8mn_esdhc_load_image(int instance, bool start);
 int imx8mp_esdhc_load_image(int instance, bool start);
 
-void imx8mm_load_and_start_image_via_tfa(void);
-void imx8mn_load_and_start_image_via_tfa(void);
-void imx8mp_load_and_start_image_via_tfa(void);
+void __noreturn imx8mm_load_and_start_image_via_tfa(void);
+void __noreturn imx8mn_load_and_start_image_via_tfa(void);
+void __noreturn imx8mp_load_and_start_image_via_tfa(void);
 
 int imx_image_size(void);
 int piggydata_size(void);