From 1b895c8371ef970ea2e556d3e122c1eac871ff70 Mon Sep 17 00:00:00 2001
From: David Karoly <karolyd577@gmail.com>
Date: Tue, 22 Feb 2022 18:17:03 +0100
Subject: [PATCH] kernel/arm: implement syscall handler

Change-Id: I75f2fb7808f55a460835276ca66cce8a26e8403d
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4980
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: X512 <danger_mail@list.ru>
Reviewed-by: Fredrik Holmqvist <fredrik.holmqvist@gmail.com>
---
 src/system/kernel/arch/arm/arch_exceptions.S | 30 ++++++++++++++--
 src/system/kernel/arch/arm/arch_int.cpp      | 36 +++++++++++++++++++-
 2 files changed, 62 insertions(+), 4 deletions(-)

diff --git a/src/system/kernel/arch/arm/arch_exceptions.S b/src/system/kernel/arch/arm/arch_exceptions.S
index 42ff0bb533..a7a792dc3e 100644
--- a/src/system/kernel/arch/arm/arch_exceptions.S
+++ b/src/system/kernel/arch/arm/arch_exceptions.S
@@ -1,5 +1,5 @@
 /*
- * Copyright 2012, Haiku Inc. All rights reserved.
+ * Copyright 2012-2022, Haiku Inc. All rights reserved.
  * Distributed under the terms of the MIT License.
  *
  * Authors:
@@ -52,6 +52,30 @@
 	ldmia	sp, {sp, lr, pc}^			/* Restore lr and exit */
 .endm
 
+/* The following two macros are adapted from the two macros above, taken from FreeBSD. */
+
+.macro	PUSHFRAMEINSWI
+	str		lr, [sp, #-4]!				/* Push the return address */
+	sub		sp, sp, #(4*17)				/* Adjust the stack pointer */
+	stmia	sp, {r0-r12}				/* Store the general purpose registers */
+	add		r0, sp, #(4*13)				/* Adjust the stack pointer */
+	stmia	r0, {r13-r14}^				/* Store the user mode sp and lr registers */
+	mrs		r0, spsr					/* Store the SPSR */
+	str		r0, [sp, #-4]!
+	mov		r0, #0						/* Fill in svc mode sp and lr with zeroes */
+	str		r0, [sp, #(4*16)]
+	str		r0, [sp, #(4*17)]
+.endm
+
+.macro	PULLFRAMEINSWIANDEXIT
+	ldr		r0, [sp], #4				/* Get SPSR from stack */
+	msr		spsr, r0
+	ldmia	sp, {r0-r14}^				/* Restore user mode registers */
+	add		sp, sp, #(4*17)				/* Adjust the stack pointer */
+	ldr		lr, [sp], #4				/* Pull the return address */
+	movs	pc, lr						/* Return to user mode */
+.endm
+
 .text
 
 .globl _vectors_start
@@ -137,12 +161,12 @@ FUNCTION_END(arm_undefined)
 
 
 FUNCTION(arm_syscall):
-	PUSHFRAMEINSVC
+	PUSHFRAMEINSWI
 
 	mov	r0, sp
 	bl	arch_arm_syscall
 
-	PULLFRAMEFROMSVCANDEXIT
+	PULLFRAMEINSWIANDEXIT
 FUNCTION_END(arm_syscall)
 
 
diff --git a/src/system/kernel/arch/arm/arch_int.cpp b/src/system/kernel/arch/arm/arch_int.cpp
index 00be3be99a..1fde42b741 100644
--- a/src/system/kernel/arch/arm/arch_int.cpp
+++ b/src/system/kernel/arch/arm/arch_int.cpp
@@ -21,7 +21,9 @@
 #include <device_manager.h>
 #include <kscheduler.h>
 #include <interrupt_controller.h>
+#include <ksyscalls.h>
 #include <smp.h>
+#include <syscall_numbers.h>
 #include <thread.h>
 #include <timer.h>
 #include <util/AutoLock.h>
@@ -30,6 +32,7 @@
 #include <vm/vm.h>
 #include <vm/vm_priv.h>
 #include <vm/VMAddressSpace.h>
+#include <algorithm>
 #include <string.h>
 
 #include <drivers/bus/FDT.h>
@@ -236,8 +239,39 @@ arch_arm_undefined(struct iframe *iframe)
 extern "C" void
 arch_arm_syscall(struct iframe *iframe)
 {
+#ifdef TRACE_ARCH_INT
 	print_iframe("Software interrupt", iframe);
-	IFrameScope scope(iframe); // push/pop iframe
+#endif
+
+	uint32_t syscall = *(uint32_t *)(iframe->pc-4) & 0x00ffffff;
+	TRACE(("syscall number: %d\n", syscall));
+
+	uint32_t args[20];
+	if (syscall < kSyscallCount) {
+		TRACE(("syscall(%s,%d)\n",
+			kExtendedSyscallInfos[syscall].name,
+			kExtendedSyscallInfos[syscall].parameter_count));
+
+		int argSize = kSyscallInfos[syscall].parameter_size;
+		memcpy(args, &iframe->r0, std::min<int>(argSize, 4 * sizeof(uint32)));
+		if (argSize > 4 * sizeof(uint32)) {
+			status_t res = user_memcpy(&args[4], (void *)iframe->usr_sp,
+				(argSize - 4 * sizeof(uint32)));
+			if (res < B_OK) {
+				dprintf("can't read syscall arguments on user stack\n");
+				iframe->r0 = res;
+				return;
+			}
+		}
+	}
+
+	enable_interrupts();
+
+	uint64 returnValue = 0;
+	syscall_dispatcher(syscall, (void*)args, &returnValue);
+
+	TRACE(("returning %" B_PRId64 "\n", returnValue));
+	iframe->r0 = returnValue;
 }