diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index de323bf..c15acdf 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -19,6 +19,19 @@ config POSITION_INDEPENDENT from almost any address. This logic relies on the relocation information that is embedded into the binary to support U-Boot relocating itself to the top-of-RAM later during execution. + +config SYS_INIT_SP_BSS_OFFSET + int + help + U-Boot typically uses a hard-coded value for the stack pointer + before relocation. Define this option to instead calculate the + initial SP at run-time. This is useful to avoid hard-coding addresses + into U-Boot, so that can be loaded and executed at arbitrary + addresses and thus avoid using arbitrary addresses at runtime. This + option's value is the offset added to &_bss_start in order to + calculate the stack pointer. This offset should be large enough so + that the early malloc region, global data (gd), and early stack usage + do not overlap any appended DTB. endif config STATIC_RELA diff --git a/arch/arm/lib/crt0_64.S b/arch/arm/lib/crt0_64.S index 9cb7055..a181283 100644 --- a/arch/arm/lib/crt0_64.S +++ b/arch/arm/lib/crt0_64.S @@ -73,6 +73,9 @@ ENTRY(_main) ldr x0, =(CONFIG_TPL_STACK) #elif defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK) ldr x0, =(CONFIG_SPL_STACK) +#elif defined(CONFIG_SYS_INIT_SP_BSS_OFFSET) + adr x0, __bss_start + add x0, x0, #CONFIG_SYS_INIT_SP_BSS_OFFSET #else ldr x0, =(CONFIG_SYS_INIT_SP_ADDR) #endif