如何在启动汇编阶段打印寄存器内容

diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index bdb5ec3..bac8bca 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -106,6 +106,7 @@ pe_header:
         * current RELR displacement
         */
 ENTRY(stext)
+ bl cl_added_proc
        bl preserve_boot_args
        bl el2_setup                       // Drop to EL1, w0=cpu_boot_mode
        adrp    x23, __PHYS_OFFSET
@@ -940,6 +941,47 @@ __relocate_kernel:
 ENDPROC(__relocate_kernel)
 #endif

+#define __UART_BUF 0x9000000
+cl_added_proc:
+ mrs     x14, sctlr_el1//-->
+ bic     x10, x14,#1
+ msr     sctlr_el1, x10
+ mov x15, #__UART_BUF
+ mov x9, #0x5b //[
+ str x9,[x15]
+
+
+ mov x13, #60
+9:
+ // ldr     x15, =0x5051525354555657 //for test
+ mov x15, x0
+ //
+ lsr x9, x15, x13
+ and x9, x9, #0xf
+ add x9, x9, 0x30
+ cmp x9, #0x39  //assic 9
+ b.le 10f
+ add x9, x9, #7
+10: mov x15, #__UART_BUF
+ str x9,[x15]
+ sub x13, x13, #4
+ cmp x13, #0
+ b.ge 9b
+
+
+
+ mov x9, #0x5d  //]
+ mov x15, #__UART_BUF
+ str x9,[x15]
+
+ mov x9, #0x0a  //
+ mov x15, #__UART_BUF
+ str x9,[x15]
+ msr     sctlr_el1, x14
+ ret
+ //<--cl_added
+ENDPROC(cl_added_proc)
+
 __primary_switch:
 #ifdef CONFIG_RANDOMIZE_BASE
        mov x19, x0                         // preserve new SCTLR_EL1 value
@@ -947,6 +989,27 @@ __primary_switch:
 #endif

        adrp    x1, init_pg_dir
+
+//===>
+ mov x19, x0
+
+ mrs     x0, CurrentEL
+ bl cl_added_proc
+ mrs x0, sctlr_el1
+ bl cl_added_proc
+ mrs x0, tcr_el1
+ bl cl_added_proc
+ mrs x0, ttbr0_el1
+ bl cl_added_proc
+ mrs x0, ttbr1_el1
+ bl cl_added_proc
+ mrs x0, VBAR_EL1
+ bl cl_added_proc
+ //mrs x0, VBAR_EL2
+ //bl cl_added_proc
+
+ mov x0, x19
+//<===
        bl __enable_mmu
 #ifdef CONFIG_RELOCATABLE