From 36acd4fce5adbbd6e98f0b0fba52f7b01bb861b4 Mon Sep 17 00:00:00 2001
From: zhangyuan21 <zhangyuan21@xiaomi.com>
Date: Thu, 11 May 2023 22:57:26 +0800
Subject: [PATCH] arch/arm64: .bss initialization using assembly language

The compiler will optimize boot_early_memset to memset,
but memset in libc cannot be used before MMU is enabled.
Therefore, assembly language is used to implement the
initialization of bss to avoid this problem.

Signed-off-by: zhangyuan21 <zhangyuan21@xiaomi.com>
---
 arch/arm64/src/common/arm64_boot.c | 16 -------------
 arch/arm64/src/common/arm64_head.S | 37 ++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 16 deletions(-)

diff --git a/arch/arm64/src/common/arm64_boot.c b/arch/arm64/src/common/arm64_boot.c
index a46fba6390..46f1a7017d 100644
--- a/arch/arm64/src/common/arm64_boot.c
+++ b/arch/arm64/src/common/arm64_boot.c
@@ -174,24 +174,8 @@ void arm64_boot_el1_init(void)
   ARM64_ISB();
 }
 
-/* These simple memset alternatives are necessary
- * as the function at libc is depend on the MMU
- * to be active.
- */
-
-static void boot_early_memset(void *dst, int c, size_t n)
-{
-  uint8_t *d = dst;
-
-  while (n--)
-    {
-      *d++ = c;
-    }
-}
-
 void arm64_boot_primary_c_routine(void)
 {
-  boot_early_memset(_START_BSS, 0, _END_BSS - _START_BSS);
   arm64_chip_boot();
   up_perf_init(NULL);
   nx_start();
diff --git a/arch/arm64/src/common/arm64_head.S b/arch/arm64/src/common/arm64_head.S
index 357fefa410..f90c0d953f 100644
--- a/arch/arm64/src/common/arm64_head.S
+++ b/arch/arm64/src/common/arm64_head.S
@@ -212,6 +212,8 @@ primary_core:
     bl    arm64_earlyprintinit
 #endif
 
+    bl    arm64_data_initialize
+
     PRINT(primary_boot, "- Ready to Boot Primary CPU\r\n")
 
 cpu_boot:
@@ -351,3 +353,38 @@ boot_stage_puts:
 .type boot_low_puts, %function;
 
 #endif /* !CONFIG_ARCH_EARLY_PRINT */
+
+/***************************************************************************
+ * Name: arm64_data_initialize
+ ***************************************************************************/
+
+    .type   arm64_data_initialize, #function
+
+arm64_data_initialize:
+
+    /* Zero BSS */
+
+    adr     x0, .Linitparms
+    ldp     x1, x2, [x0], #8
+
+    mov     x0, #0
+1:
+    cmp     x1, x2
+    bge     2f
+    str     x0, [x1], #8
+    b       1b
+2:
+    ret
+    .size   arm64_data_initialize, . - arm64_data_initialize
+
+/***************************************************************************
+ * Text-section constants
+ ***************************************************************************/
+
+    .data
+    .align  8
+    .type   .Linitparms, %object
+.Linitparms:
+    .quad   _sbss
+    .quad   _ebss
+    .size   .Linitparms, . -.Linitparms