[PATCH 2/5] arm64: PIE: Allow fixed stack pointer
Andre Przywara
andre.przywara at arm.com
Thu Sep 24 02:17:12 CEST 2020
Currently selecting CONFIG_POSITION_INDEPENDENT also forces us to use an
initial stack pointer address relative to the load address. This makes
some sense, assuming there is some usable memory nearby.
However if U-Boot is started from some kind of ROM, a stack pointer
nearby will probably also end up in ROM, which is not very helpful.
Allow CONFIG_INIT_SP_RELATIVE to be turned off by a board's config, to
be able to select a fixed stack pointer, for instance in known good
DRAM.
This will help QEMU utilising PIE, when it's loaded to (Flash-)ROM.
Signed-off-by: Andre Przywara <andre.przywara at arm.com>
---
Verified all boards using CONFIG_POSITION_INDEPENDENT to generate the
same .config, before and after this patch.
Cheers,
Andre
arch/arm/Kconfig | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 80702c23d34..d079e1930fc 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -12,7 +12,6 @@ config ARM64
if ARM64
config POSITION_INDEPENDENT
bool "Generate position-independent pre-relocation code"
- select INIT_SP_RELATIVE
help
U-Boot expects to be linked to a specific hard-coded address, and to
be loaded to and run from that address. This option lifts that
@@ -23,6 +22,7 @@ config POSITION_INDEPENDENT
config INIT_SP_RELATIVE
bool "Specify the early stack pointer relative to the .bss section"
+ default y if POSITION_INDEPENDENT
help
U-Boot typically uses a hard-coded value for the stack pointer
before relocation. Enable this option to instead calculate the
--
2.17.5
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