examples: fix building on arm64

Commit f9886bc60f42 ("Added arm64 assembly for examples/api crt0") tried to
add arm64 support to the examples but crt0.S does not even build for
qemu_arm64_defconfig with CONFIG_API=y, CONFIG_EXAMPLES=y:

    examples/api/crt0.S: Assembler messages:
    examples/api/crt0.S:32: Error:
        expected a register at operand 1 -- `ldr ip,=search_hint'
    examples/api/crt0.S:33: Error:
        unexpected register type at operand 1 -- `str sp,[ip]'
    make[2]: *** [scripts/Makefile.build:292: examples/api/crt0.o] Error 1

Do not define _start twice.
Use valid register names.
Move syscall_ptr and search_hint to the data section to avoid an invalid
relocation.

Fixes: f9886bc60f42 ("Added arm64 assembly for examples/api crt0")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>

diff --git a/examples/api/crt0.S b/examples/api/crt0.S
index 06f6d1f9ad4dcac05d16eeedb3044a03c9c14075..f1b88ed8a3dc8ae3fb7c72cd195ef771417095b2 100644 (file)
--- a/examples/api/crt0.S
+++ b/examples/api/crt0.S
@@ -24,7 +24,7 @@ syscall:
        mtctr   %r11
        bctr
 
-#elif defined(CONFIG_ARM)
+#elif defined(CONFIG_ARM) && !defined(CONFIG_ARM64)
 
        .text
        .globl _start
@@ -33,26 +33,27 @@ _start:
        str     sp, [ip]
        b       main
 
-#elif defined(CONFIG_ARM64)
-
-              .text
-              .globl _start
-_start:
-              ldr           ip0, =search_hint
-              str           sp_el2, [ip0]
-              b             main
 
-
-              .globl syscall
+       .globl syscall
 syscall:
-              ldr           ip0, =syscall_ptr
-              ldr           pc_el2, [ip0]
+       ldr     ip, =syscall_ptr
+       ldr     pc, [ip]
 
+#elif defined(CONFIG_ARM64)
+
+       .text
+       .globl _start
+_start:
+       ldr     x17, =search_hint
+       mov     x16, sp
+       str     x16, [x17]
+       b       main
 
        .globl syscall
 syscall:
-       ldr     ip, =syscall_ptr
-       ldr     pc, [ip]
+       ldr     x16, =syscall_ptr
+       ldr     x16, [x16]
+       br      x16
 
 #elif defined(CONFIG_MIPS)
 #include <asm/asm.h>
@@ -83,6 +84,8 @@ return_addr:
 #error No support for this arch!
 #endif
 
+.section .data
+
        .globl syscall_ptr
 syscall_ptr:
        .align  8
@@ -90,4 +93,4 @@ syscall_ptr:
 
        .globl search_hint
 search_hint:
-       .long   0
+       .long   0