Re: [PATCH v2 1/3] ARM: i.MX8M: atf: mark ATF start functions as __noreturn

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On Tue, Aug 16, 2022 at 09:30:54AM +0200, Ahmad Fatoum wrote:
> 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@xxxxxxxxxxxxxx>
> ---
> v1 -> v2:
>   - no change
> ---
>  arch/arm/mach-imx/atf.c                | 26 ++++++++++----------------
>  arch/arm/mach-imx/include/mach/atf.h   | 10 ++++++----
>  arch/arm/mach-imx/include/mach/xload.h |  9 ++++++---
>  3 files changed, 22 insertions(+), 23 deletions(-)

Applied, thanks

Sascha

> 
> diff --git a/arch/arm/mach-imx/atf.c b/arch/arm/mach-imx/atf.c
> index a4c658283006..df23dbfc0e5a 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 bc400ddbad4c..ca54bb5fbf82 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 3090c9c83bd7..fe43d2502632 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);
> -- 
> 2.30.2
> 
> 
> 

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