[PATCH] armv8: Skip PIE in SPL due to load alignment fault.

[PATCH] armv8: Skip PIE in SPL due to load alignment fault.

[Kevin Chen]

When PIE is enabled in start.S, u-boot/-spl use __rel_dyn_start
and _rel_dyn_end symbol to be loaded to and executed at a
different address than it was linked at.

u-boot-spl.lds is used in SPL build, but relocation information
section(.rela*) were discarded.
In line number 80 in arch/arm/cpu/armv8/u-boot-spl.lds
 /DISCARD/ : { *(.rela*) }

If PIE enabled in SPL, __rel_dyn_start which is defined as
.rel_dyn_start in sections.c will be apended to the end of
.bss section.

In our ASPEED case, size of .bss section would let .rel_dyn_start
without 8-byte alignment, leading to alignment fault when
executing ldp instuction in pie_fix_loop.

Signed-off-by: Kevin Chen <kevin_chen@aspeedtech.com>
---
 arch/arm/cpu/armv8/start.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/cpu/armv8/start.S b/arch/arm/cpu/armv8/start.S
index f3ea858577..6cc1d26e5e 100644
--- a/arch/arm/cpu/armv8/start.S
+++ b/arch/arm/cpu/armv8/start.S
@@ -58,7 +58,7 @@ reset:
 .globl	save_boot_params_ret
 save_boot_params_ret:
 
-#if CONFIG_POSITION_INDEPENDENT
+#if CONFIG_POSITION_INDEPENDENT && !defined(CONFIG_SPL_BUILD)
 	/* Verify that we're 4K aligned.  */
 	adr	x0, _start
 	ands	x0, x0, #0xfff
-- 
2.41.0

Re: [PATCH] armv8: Skip PIE in SPL due to load alignment fault.

[Tom Rini]

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On Thu, Aug 03, 2023 at 04:12:18PM +0800, Kevin Chen wrote:

> When PIE is enabled in start.S, u-boot/-spl use __rel_dyn_start
> and _rel_dyn_end symbol to be loaded to and executed at a
> different address than it was linked at.
> 
> u-boot-spl.lds is used in SPL build, but relocation information
> section(.rela*) were discarded.
> In line number 80 in arch/arm/cpu/armv8/u-boot-spl.lds
>  /DISCARD/ : { *(.rela*) }
> 
> If PIE enabled in SPL, __rel_dyn_start which is defined as
> .rel_dyn_start in sections.c will be apended to the end of
> .bss section.
> 
> In our ASPEED case, size of .bss section would let .rel_dyn_start
> without 8-byte alignment, leading to alignment fault when
> executing ldp instuction in pie_fix_loop.
> 
> Signed-off-by: Kevin Chen <kevin_chen@aspeedtech.com>

Applied to u-boot/next, thanks!

-- 
Tom

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