From 1effe3b9ac0bb1a819f6ae5ebb8438e60b77f9a2 Mon Sep 17 00:00:00 2001
From: Aleksa Vuckovic <aleksav013@gmail.com>
Date: Wed, 7 Sep 2022 22:10:02 +0200
Subject: syscall

---
 kernel/src/cpu/tss.c           |  1 -
 kernel/src/main.c              |  2 +-
 kernel/src/sys/syscall.S       |  0
 kernel/src/sys/syscall.c       |  9 +++++++++
 kernel/src/sys/syscall_asm.S   | 40 ++++++++++++++++++++++++++++++++++++++++
 kernel/src/sys/userspace.c     |  4 +++-
 kernel/src/sys/userspace_asm.S |  5 +++++
 7 files changed, 58 insertions(+), 3 deletions(-)
 delete mode 100644 kernel/src/sys/syscall.S
 create mode 100644 kernel/src/sys/syscall.c
 create mode 100644 kernel/src/sys/syscall_asm.S

(limited to 'kernel/src')

diff --git a/kernel/src/cpu/tss.c b/kernel/src/cpu/tss.c
index 843c114..a1224f6 100644
--- a/kernel/src/cpu/tss.c
+++ b/kernel/src/cpu/tss.c
@@ -18,5 +18,4 @@ void init_tss()
 	tss.rsp0_high = (uint32_t)(stack >> 32);
 
 	load_tss();
-	printf("rsp0 addr in tss: 0x%x\n", stack);
 }
diff --git a/kernel/src/main.c b/kernel/src/main.c
index 4b0d62a..03e0168 100644
--- a/kernel/src/main.c
+++ b/kernel/src/main.c
@@ -25,8 +25,8 @@ int kernel_main(mb2_tag_header* multiboot_bootinfo, uint32_t multiboot_magic)
 	init_timer(TICKS_PER_SECOND);
 	init_idt();
 	init_heap();
-	read_mb2(multiboot_bootinfo, multiboot_magic);
 	init_tss();
+	read_mb2(multiboot_bootinfo, multiboot_magic);
 //	disc_init();
 //	ext2_init();
 //	ls(path_to_inode("/"));
diff --git a/kernel/src/sys/syscall.S b/kernel/src/sys/syscall.S
deleted file mode 100644
index e69de29..0000000
diff --git a/kernel/src/sys/syscall.c b/kernel/src/sys/syscall.c
new file mode 100644
index 0000000..7f0e492
--- /dev/null
+++ b/kernel/src/sys/syscall.c
@@ -0,0 +1,9 @@
+#include <libk/stdio.h>
+#include <syscall.h>
+
+void syscall_handler()
+{
+	uint64_t rax;
+	__asm__ volatile ("mov %%rax, %0;" : "=r"(rax) : :);
+	printf("syscall invoked with rax=0x%x\n", rax);
+}
diff --git a/kernel/src/sys/syscall_asm.S b/kernel/src/sys/syscall_asm.S
new file mode 100644
index 0000000..a9942ca
--- /dev/null
+++ b/kernel/src/sys/syscall_asm.S
@@ -0,0 +1,40 @@
+.extern syscall_handler
+
+.macro pushall
+	push %rax
+	push %rcx
+	push %rdx
+	push %rsi
+	push %rdi
+	push %r8
+	push %r9
+	push %r10
+	push %r11
+	pushfq
+.endm
+
+.macro popall
+	popfq
+	pop %r11
+	pop %r10
+	pop %r9
+	pop %r8
+	pop %rdi
+	pop %rsi
+	pop %rdx
+	pop %rcx
+	pop %rax
+.endm
+
+.global __syscall
+__syscall:
+	pushq %rcx
+	pushq %r11
+
+	pushall
+	call syscall_handler
+	popall
+
+	popfq
+	popq %rcx
+	sysretq
diff --git a/kernel/src/sys/userspace.c b/kernel/src/sys/userspace.c
index 4add4d5..111180a 100644
--- a/kernel/src/sys/userspace.c
+++ b/kernel/src/sys/userspace.c
@@ -3,7 +3,9 @@
 
 void begin_userspace()
 {
+	__asm__ volatile ("mov $0x1, %rax; syscall;");
+	__asm__ volatile ("mov $0x11, %rax; syscall;");
+	__asm__ volatile ("mov $0x111, %rax; syscall;");
 	while(true) {
-
 	}
 }
diff --git a/kernel/src/sys/userspace_asm.S b/kernel/src/sys/userspace_asm.S
index c722df0..5817a8c 100644
--- a/kernel/src/sys/userspace_asm.S
+++ b/kernel/src/sys/userspace_asm.S
@@ -1,6 +1,7 @@
 .text
 
 .extern begin_userspace
+.extern syscall_handler
 
 .global jump_userspace
 jump_userspace:
@@ -11,6 +12,10 @@ jump_userspace:
 	mov %ax, %gs
 
 	mov $0xc0000082, %rcx
+	movabs $__syscall, %rax
+	shr $32, %rax
+	mov %eax, %edx
+	movabs $__syscall, %rax
 	wrmsr
 	mov $0xc0000080, %rcx
 	rdmsr
-- 
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