From 0b0184de760cfc27155658d71e75eb4d3b1e53b8 Mon Sep 17 00:00:00 2001
From: Matheus <matheusuky@gmail.com>
Date: Wed, 10 May 2023 21:20:31 -0300
Subject: [PATCH] kernel: archctl syscall

---
 kernel-src/arch/x86-64/archctl.c       | 28 +++++++++++++++++++++
 kernel-src/arch/x86-64/syscall.asm     |  4 ++-
 patches/mlibc/jinx-working-patch.patch | 35 +++++++++++++++++++++-----
 3 files changed, 60 insertions(+), 7 deletions(-)
 create mode 100644 kernel-src/arch/x86-64/archctl.c

diff --git a/kernel-src/arch/x86-64/archctl.c b/kernel-src/arch/x86-64/archctl.c
new file mode 100644
index 00000000..26ba5f3e
--- /dev/null
+++ b/kernel-src/arch/x86-64/archctl.c
@@ -0,0 +1,28 @@
+#include <kernel/syscalls.h>
+#include <arch/msr.h>
+#include <errno.h>
+
+#define ARCH_CTL_GSBASE 0
+#define ARCH_CTL_FSBASE 1
+
+syscallret_t syscall_archctl(context_t *context, int func, void *arg) {
+	syscallret_t ret = {
+		.errno = 0,
+		.ret = 0
+	};
+
+	switch (func) {
+		case ARCH_CTL_GSBASE:
+			// kernelgsbase because it will be switched out to user
+			wrmsr(MSR_KERNELGSBASE, (uint64_t)arg);
+			break;
+		case ARCH_CTL_FSBASE:
+			wrmsr(MSR_FSBASE, (uint64_t)arg);
+			break;
+		default:
+			ret.errno = EINVAL;
+			break;
+	}
+
+	return ret;
+}
diff --git a/kernel-src/arch/x86-64/syscall.asm b/kernel-src/arch/x86-64/syscall.asm
index 99ba7391..1046d6a6 100644
--- a/kernel-src/arch/x86-64/syscall.asm
+++ b/kernel-src/arch/x86-64/syscall.asm
@@ -5,6 +5,7 @@ extern syscall_openat
 extern syscall_read
 extern syscall_seek
 extern syscall_close
+extern syscall_archctl
 syscalltab:
 dq syscall_print
 dq syscall_mmap
@@ -12,7 +13,8 @@ dq syscall_openat
 dq syscall_read
 dq syscall_seek
 dq syscall_close
-syscallcount equ 6
+dq syscall_archctl
+syscallcount equ 7
 section .text
 global arch_syscall_entry
 ; on entry:
diff --git a/patches/mlibc/jinx-working-patch.patch b/patches/mlibc/jinx-working-patch.patch
index e25f861d..fce6eb03 100644
--- a/patches/mlibc/jinx-working-patch.patch
+++ b/patches/mlibc/jinx-working-patch.patch
@@ -71,7 +71,27 @@ index 0000000..0a0a4a0
 +
 diff --git mlibc-workdir/sysdeps/astral/generic/astral.cpp mlibc-workdir/sysdeps/astral/generic/astral.cpp
 new file mode 100644
-index 0000000..e69de29
+index 0000000..7d5b1e3
+--- /dev/null
++++ mlibc-workdir/sysdeps/astral/generic/astral.cpp
+@@ -0,0 +1,17 @@
++#include <astral/archctl.h>
++#include <errno.h>
++
++#define ARCH_CTL_GSBASE 0
++#define ARCH_CTL_FSBASE 1
++
++#ifndef MLIBC_BUILDING_RTDL
++
++int syscall_archctl(int func, void *arg) {
++	long ret;
++	long error = syscall(SYSCALL_ARCHCTL, &ret, func, (uint64_t)arg);
++	if (error)
++		errno = error;
++	return error ? -1 : ret;
++}
++
++#endif
 diff --git mlibc-workdir/sysdeps/astral/generic/entry.cpp mlibc-workdir/sysdeps/astral/generic/entry.cpp
 new file mode 100644
 index 0000000..e5b087a
@@ -113,10 +133,10 @@ index 0000000..e5b087a
 +
 diff --git mlibc-workdir/sysdeps/astral/generic/generic.cpp mlibc-workdir/sysdeps/astral/generic/generic.cpp
 new file mode 100644
-index 0000000..0f88fe5
+index 0000000..1bf8c55
 --- /dev/null
 +++ mlibc-workdir/sysdeps/astral/generic/generic.cpp
-@@ -0,0 +1,152 @@
+@@ -0,0 +1,154 @@
 +#include <bits/ensure.h>
 +#include <mlibc/debug.hpp>
 +#include <mlibc/all-sysdeps.hpp>
@@ -197,7 +217,8 @@ index 0000000..0f88fe5
 +	}
 +
 +	int sys_tcb_set(void *pointer) {
-+		return ENOSYS;
++		long r;
++		return syscall(SYSCALL_ARCHCTL, &r, ARCH_CTL_FSBASE, (uint64_t)pointer);
 +	}
 +
 +	int sys_futex_wait(int *pointer, int expected, const struct timespec *time) {
@@ -236,6 +257,7 @@ index 0000000..0f88fe5
 +	int sys_write(int fd, const void *buff, size_t count, ssize_t *bytes_written) {
 +		return ENOSYS;
 +	}
++
 +	int sys_seek(int fd, off_t offset, int whence, off_t *new_offset) {
 +		long ret = 0;
 +		long error = syscall(SYSCALL_SEEK, &ret, fd, offset, whence);
@@ -288,10 +310,10 @@ index 0000000..990eca0
 +#endif
 diff --git mlibc-workdir/sysdeps/astral/include/astral/syscall.h mlibc-workdir/sysdeps/astral/include/astral/syscall.h
 new file mode 100644
-index 0000000..bb2e40d
+index 0000000..2d4b960
 --- /dev/null
 +++ mlibc-workdir/sysdeps/astral/include/astral/syscall.h
-@@ -0,0 +1,29 @@
+@@ -0,0 +1,30 @@
 +#ifndef _SYSCALL_H_INCLUDE
 +#define _SYSCALL_H_INCLUDE
 +
@@ -301,6 +323,7 @@ index 0000000..bb2e40d
 +#define SYSCALL_READ 3
 +#define SYSCALL_SEEK 4
 +#define SYSCALL_CLOSE 5
++#define SYSCALL_ARCHCTL 6
 +
 +#include <stddef.h>
 +#include <stdint.h>