[PATCH v2 3/3] arm64: Add support for larger PIE U-boot
Michal Simek
michal.simek at xilinx.com
Fri Sep 4 15:04:02 CEST 2020
On 04. 09. 20 11:07, Edgar E. Iglesias wrote:
> From: "Edgar E. Iglesias" <edgar.iglesias at xilinx.com>
>
> Linking a U-boot larger than 1MB fails with PIE enabled:
> u-boot/arch/arm/cpu/armv8/start.S:71:(.text+0x3c): relocation
> truncated to fit: R_AARCH64_ADR_PREL_LO21 against symbol `__rel_dyn_end'
> defined in .bss_start section in u-boot.
>
> This extends the supported range by using adrp & add to load symbols
> early while starting up.
>
> Signed-off-by: Edgar E. Iglesias <edgar.iglesias at xilinx.com>
> ---
> arch/arm/cpu/armv8/start.S | 6 ++++--
> arch/arm/lib/crt0_64.S | 3 ++-
> 2 files changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm/cpu/armv8/start.S b/arch/arm/cpu/armv8/start.S
> index 732bc385d4..335783014c 100644
> --- a/arch/arm/cpu/armv8/start.S
> +++ b/arch/arm/cpu/armv8/start.S
> @@ -84,8 +84,10 @@ pie_fixup:
> adr x0, _start /* x0 <- Runtime value of _start */
> ldr x1, _TEXT_BASE /* x1 <- Linked value of _start */
> sub x9, x0, x1 /* x9 <- Run-vs-link offset */
> - adr x2, __rel_dyn_start /* x2 <- Runtime &__rel_dyn_start */
> - adr x3, __rel_dyn_end /* x3 <- Runtime &__rel_dyn_end */
> + adrp x2, __rel_dyn_start /* x2 <- Runtime &__rel_dyn_start */
> + add x2, x2, #:lo12:__rel_dyn_start
> + adrp x3, __rel_dyn_end /* x3 <- Runtime &__rel_dyn_end */
> + add x3, x3, #:lo12:__rel_dyn_end
> pie_fix_loop:
> ldp x0, x1, [x2], #16 /* (x0, x1) <- (Link location, fixup) */
> ldr x4, [x2], #8 /* x4 <- addend */
> diff --git a/arch/arm/lib/crt0_64.S b/arch/arm/lib/crt0_64.S
> index 04afa518ac..f28071a238 100644
> --- a/arch/arm/lib/crt0_64.S
> +++ b/arch/arm/lib/crt0_64.S
> @@ -102,7 +102,8 @@ ENTRY(_main)
> adr lr, relocation_return
> #if CONFIG_POSITION_INDEPENDENT
> /* Add in link-vs-runtime offset */
> - adr x0, _start /* x0 <- Runtime value of _start */
> + adrp x0, _start /* x0 <- Runtime value of _start */
> + add x0, x0, #:lo12:_start
> ldr x9, _TEXT_BASE /* x9 <- Linked value of _start */
> sub x9, x9, x0 /* x9 <- Run-vs-link offset */
> add lr, lr, x9
>
I have tested 21MB and 51MB u-boot and there is need to also patch
__bss_start.
--- a/arch/arm/lib/crt0_64.S
+++ b/arch/arm/lib/crt0_64.S
@@ -73,7 +73,12 @@ ENTRY(_main)
#elif defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK)
ldr x0, =(CONFIG_SPL_STACK)
#elif defined(CONFIG_INIT_SP_RELATIVE)
+#if CONFIG_POSITION_INDEPENDENT
+ adrp x0, __bss_start /* x0 <- Runtime &__bss_start */
+ add x0, x0, #:lo12:__bss_start
+#else
adr x0, __bss_start
+#endif
add x0, x0, #CONFIG_SYS_INIT_SP_BSS_OFFSET
#else
ldr x0, =(CONFIG_SYS_INIT_SP_ADDR)
Thanks,
Michal
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