core: ldelf: implement separate syscalls for ldelf

Implements a separate syscall handler for ldelf to decouple it from user
TAs and enable using it for all TSs. The calling convention is the same
as for utee_* syscalls. To distinguish between the different SVCs, the
syscall handler pointer is updated before entering ldelf and restored
after returning. The step of opening a system PTA session and invoking
the commands there is eliminated, the necessary functionality is
implemented in the ldelf syscall functions.

Acked-by: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Balint Dobszay <balint.dobszay@arm.com>

1 files changed, 51 insertions, 0 deletions

diff --git a/ldelf/syscalls_a32.S b/ldelf/syscalls_a32.S
new file mode 100644
index 00000000..332fa94c
--- /dev/null
+++ b/ldelf/syscalls_a32.S
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (c) 2014, STMicroelectronics International N.V.
+ * Copyright (c) 2015, Linaro Limited
+ * Copyright (c) 2020, Arm Limited
+ */
+
+#include <asm.S>
+
+	.section .text
+	.balign 4
+	.code 32
+
+	.macro LDELF_SYSCALL name, scn, num_args
+	FUNC \name , :
+
+	.if \num_args > 8
+	.error "Too many arguments for syscall"
+	.endif
+
+	push	{r5-r7, lr}
+UNWIND(	.save	{r5-r7, lr})
+	mov	r7, #(\scn)
+
+	.if \num_args <= 4
+	@ No arguments passed on stack
+	mov	r6, #0
+	.else
+	@ Tell number of arguments passed on the stack
+	mov	r6, #(\num_args - 4)
+	@ Point just before the push (4 registers) above on the first argument
+	add	r5, sp, #(4 * 4)
+	.endif
+
+	svc	#0
+	pop	{r5-r7, pc}
+	END_FUNC \name
+	.endm
+
+	FUNC _ldelf_panic, :
+	push	{r0-r11, lr}
+UNWIND(	.save	{r0-r11, lr})
+	mov	lr, pc
+	push	{lr}
+UNWIND(	.save	{lr})
+	mov	r1, sp
+	bl	__ldelf_panic
+	/* Not reached */
+	END_FUNC _ldelf_panic
+
+#include "syscalls_asm.S"