Hi, all
I found a bug on AARCH64 platform about clean .bss section after relocating.
In crt0_64.S, it use instruction 'ldr' to load the start/stop
address of BSS after relocating. My testing shows that
__bss_start loaded successfuly, but 'x1 <= __bss_end' got the
address _BEFORE_ allocating.
If I swap the two instruction sequence, the result is swapped
also. But neither code can gives the right result of those two
addesses _AFTER_ relocation.
my patch use 'adr' instead of 'ldr', seems OK for my RK3568 chip.
--
Brock Zheng <[email protected]>
郑 祎
北京中科腾越科技发展有限公司
北京市 海淀区 东北旺西路8号 中关村软件园27号院 千方大厦A座2层 (邮编:100193)
>From 799060d6d373236951afa9d3e571b36fc9e9d026 Mon Sep 17 00:00:00 2001
From: Brock Zheng <[email protected]>
Date: Sun, 29 Jun 2025 12:34:17 +0800
Subject: [PATCH] arm64: fix up .bss section cleaning after relocating
__bss_start/__bss_end is not loaded correctly by instruction 'ldr'
using 'adr' instead. Seems OK on RK3568 SoC.
---
arch/arm/lib/crt0_64.S | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/arm/lib/crt0_64.S b/arch/arm/lib/crt0_64.S
index 30950ddaf9b..b45c1b65dc4 100644
--- a/arch/arm/lib/crt0_64.S
+++ b/arch/arm/lib/crt0_64.S
@@ -158,8 +158,8 @@ relocation_return:
/*
* Clear BSS section
*/
- ldr x0, =__bss_start /* this is auto-relocated! */
- ldr x1, =__bss_end /* this is auto-relocated! */
+ adr x0, __bss_start /* this is auto-relocated! */
+ adr x1, __bss_end /* this is auto-relocated! */
clear_loop:
str xzr, [x0], #8
cmp x0, x1
--
2.50.0
