[PATCH v2 2/2] ARM: setup_c: avoid clearing BSS twice

[Sascha Hauer]

Add a bss_cleared variable that is set after the first call to
setup_c(). On subsequent calls, the BSS clear is skipped to avoid
wiping already-initialized data.

Co-Authored-By: Claude Opus 4.6 <noreply at anthropic.com>
Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
 arch/arm/cpu/setupc_32.S | 15 +++++++++++++--
 arch/arm/cpu/setupc_64.S | 14 ++++++++++++--
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/arch/arm/cpu/setupc_32.S b/arch/arm/cpu/setupc_32.S
index c2c3f97528..4a5e2f9e96 100644
--- a/arch/arm/cpu/setupc_32.S
+++ b/arch/arm/cpu/setupc_32.S
@@ -7,18 +7,29 @@
 .section .text.setupc
 
 /*
- * setup_c: clear bss
+ * setup_c: clear bss if not yet done
  */
 ENTRY(setup_c)
 	mov	r4, lr
+	ldr	r0, =bss_cleared
+	ldr	r1, [r0]
+	cmp	r1, #0
+	bne	1f			/* skip if already done */
 	ldr	r0, =__bss_start
 	mov	r1, #0
 	ldr	r2, =__bss_stop
 	sub	r2, r2, r0
 	bl	__memset		/* clear bss */
-	ret	r4
+	ldr	r0, =bss_cleared
+	mov	r1, #1
+	str	r1, [r0]		/* mark bss cleared */
+1:	ret	r4
 ENDPROC(setup_c)
 
+.section .data
+bss_cleared:
+	.word 	0
+
 /*
  * void relocate_to_adr(unsigned long targetadr)
  *
diff --git a/arch/arm/cpu/setupc_64.S b/arch/arm/cpu/setupc_64.S
index fd95187a04..caa16d3582 100644
--- a/arch/arm/cpu/setupc_64.S
+++ b/arch/arm/cpu/setupc_64.S
@@ -7,19 +7,29 @@
 .section .text.setupc
 
 /*
- * setup_c: clear bss
+ * setup_c: clear bss if not yet done
  */
 ENTRY(setup_c)
+	adr_l	x0, bss_cleared
+	ldr	w1, [x0]
+	cbnz	w1, 1f			/* skip if already done */
 	mov	x15, x30
 	adr_l	x0, __bss_start
 	mov	x1, #0
 	adr_l	x2, __bss_stop
 	sub	x2, x2, x0
 	bl	__memset		/* clear bss */
+	adr_l	x0, bss_cleared
+	mov	w1, #1
+	str	w1, [x0]		/* mark bss cleared */
 	mov	x30, x15
-	ret
+1:	ret
 ENDPROC(setup_c)
 
+.section .data
+bss_cleared:
+	.word 	0
+
 /*
  * void relocate_to_adr(unsigned long targetadr)
  *

-- 
2.47.3