From e6c904489a6018f44c3b00c9eacc4742887b1f83 Mon Sep 17 00:00:00 2001 From: Stephen Warren Date: Tue, 19 Dec 2017 18:30:36 -0700 Subject: ARMv8: Allow dynamic early stack pointer U-Boot typically uses a hard-coded value for the stack pointer before relocation. Implement option SYS_INIT_SP_BSS_OFFSET 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. Signed-off-by: Stephen Warren Signed-off-by: Tom Warren --- arch/arm/lib/crt0_64.S | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/arm/lib') diff --git a/arch/arm/lib/crt0_64.S b/arch/arm/lib/crt0_64.S index 9cb70552fe..a181283e0f 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 -- cgit v1.2.1