[PATCH 1/2] ARM: cpu: setupc: relocate BSS in relocate_to_adr()

[PATCH 1/2] ARM: cpu: setupc: relocate BSS in relocate_to_adr()

[Ahmad Fatoum]

When calling relocate_to_adr(), barebox is copied without BSS to a new
place. The new BSS region is not necessarily zeroed, but setupc()
following relocate_to_adr() will take care of that.

With incoming change to make setupc() idempotent, this will become
problematic as the variable in .data will indicate that the BSS is
zeroed, while the new BSS region isn't actually.

We usually have very little BSS in the PBL, so copying it is not much
more effort, so let's just do that.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
Please apply before "ARM: setup_c: avoid clearing BSS twice"
---
 arch/arm/cpu/setupc_32.S | 4 ++--
 arch/arm/cpu/setupc_64.S | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm/cpu/setupc_32.S b/arch/arm/cpu/setupc_32.S
index 61b8152599f1..c5348353b129 100644
--- a/arch/arm/cpu/setupc_32.S
+++ b/arch/arm/cpu/setupc_32.S
@@ -39,12 +39,12 @@ bss_cleared:
 .section .text.relocate_to_adr
 #ifdef __PBL__
 ENTRY(relocate_to_adr_full)
-	ldr	r2, =__image_end
+	ldr	r2, =__image_end	/* include piggy data */
 	b	1f
 #endif
 
 ENTRY(relocate_to_adr)
-	ldr	r2, =__bss_start
+	ldr	r2, =__bss_stop		/* skip piggy data */
 	b	1f
 
 1:
diff --git a/arch/arm/cpu/setupc_64.S b/arch/arm/cpu/setupc_64.S
index 8fd7f2f9b60f..d5a6c0c43a7b 100644
--- a/arch/arm/cpu/setupc_64.S
+++ b/arch/arm/cpu/setupc_64.S
@@ -40,12 +40,12 @@ bss_cleared:
 					/* x0: target address */
 #ifdef __PBL__
 ENTRY(relocate_to_adr_full)
-	adr_l	x2, __image_end
+	adr_l	x2, __image_end		/* include piggy data */
 	b	1f
 #endif
 
 ENTRY(relocate_to_adr)
-	adr_l	x2, __bss_start
+	adr_l	x2, __bss_stop		/* skip piggy data */
 	b	1f
 
 1:
-- 
2.47.3

[PATCH 2/2] fixup! ARM: setup_c: avoid clearing BSS twice

[Ahmad Fatoum]

ARM: setup_c: ensure 4-byte alignment for bss_cleared

Out of abundance of caution, avoid the variable ending up being
misaligned.

I did not observe this happening.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 arch/arm/cpu/setupc_32.S | 1 +
 arch/arm/cpu/setupc_64.S | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/arm/cpu/setupc_32.S b/arch/arm/cpu/setupc_32.S
index c5348353b129..fadfc28ae155 100644
--- a/arch/arm/cpu/setupc_32.S
+++ b/arch/arm/cpu/setupc_32.S
@@ -27,6 +27,7 @@ ENTRY(setup_c)
 ENDPROC(setup_c)
 
 .section .data.bss_cleared
+.balign 4
 bss_cleared:
 	.word 	0
 
diff --git a/arch/arm/cpu/setupc_64.S b/arch/arm/cpu/setupc_64.S
index d5a6c0c43a7b..a0767c5136e0 100644
--- a/arch/arm/cpu/setupc_64.S
+++ b/arch/arm/cpu/setupc_64.S
@@ -27,6 +27,7 @@ ENTRY(setup_c)
 ENDPROC(setup_c)
 
 .section .data.bss_cleared
+.balign 4
 bss_cleared:
 	.word 	0
 
-- 
2.47.3

Re: [PATCH 1/2] ARM: cpu: setupc: relocate BSS in relocate_to_adr()

[Sascha Hauer]

On Thu, 12 Mar 2026 20:20:42 +0100, Ahmad Fatoum wrote:
> When calling relocate_to_adr(), barebox is copied without BSS to a new
> place. The new BSS region is not necessarily zeroed, but setupc()
> following relocate_to_adr() will take care of that.
> 
> With incoming change to make setupc() idempotent, this will become
> problematic as the variable in .data will indicate that the BSS is
> zeroed, while the new BSS region isn't actually.
> 
> [...]

Applied, thanks!

[1/2] ARM: cpu: setupc: relocate BSS in relocate_to_adr()
      https://git.pengutronix.de/cgit/barebox/commit/?id=d443585bcce6 (link may not be stable)
[2/2] fixup! ARM: setup_c: avoid clearing BSS twice
      (no commit info)

Best regards,
-- 
Sascha Hauer <s.hauer@pengutronix.de>

Re: [PATCH 1/2] ARM: cpu: setupc: relocate BSS in relocate_to_adr()

[Ahmad Fatoum]

Hello Sascha,

On 3/13/26 12:17, Sascha Hauer wrote:
> 
> On Thu, 12 Mar 2026 20:20:42 +0100, Ahmad Fatoum wrote:
>> When calling relocate_to_adr(), barebox is copied without BSS to a new
>> place. The new BSS region is not necessarily zeroed, but setupc()
>> following relocate_to_adr() will take care of that.
>>
>> With incoming change to make setupc() idempotent, this will become
>> problematic as the variable in .data will indicate that the BSS is
>> zeroed, while the new BSS region isn't actually.
>>
>> [...]
> 
> Applied, thanks!
> 
> [1/2] ARM: cpu: setupc: relocate BSS in relocate_to_adr()
>       https://git.pengutronix.de/cgit/barebox/commit/?id=d443585bcce6 (link may not be stable)
> [2/2] fixup! ARM: setup_c: avoid clearing BSS twice

Please reorder "ARM: cpu: setupc: relocate BSS in relocate_to_adr" before "ARM: setup_c: avoid clearing BSS twice" to keep bisection possible without intermittent breakage.

Thanks,
Ahmad

>       (no commit info)
> 
> Best regards,


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