kernel: fork syscall

kernel-src/arch/x86-64/syscall.asm

@@ -10,6 +10,7 @@ extern syscall_write
 extern syscall_getpid
 extern syscall_fstat
 extern syscall_fstatat
+extern syscall_fork
 syscalltab:
 dq syscall_print
 dq syscall_mmap
@@ -22,7 +23,8 @@ dq syscall_write
 dq syscall_getpid
 dq syscall_fstat
 dq syscall_fstatat
-syscallcount equ 11
+dq syscall_fork
+syscallcount equ 12
 section .text
 global arch_syscall_entry
 ; on entry:
@@ -49,7 +51,7 @@ arch_syscall_entry:
 
 	; push context
 	push qword 0x1b ; user SS
-	push qword rcx
+	push qword rcx  ; user RSP
 	add qword [rsp], 8 ; correct the old stack pointer to before the return address push
 	push r11     ; rflags is stored in r11
 	push qword 0x23 ; user CS
@@ -89,6 +91,7 @@ arch_syscall_entry:
 	mov rdx, rsi
 	mov rsi, rdi
 	mov rdi, rsp
+	add rdi, 8 ; context pointer is after r9 argument
 	sti
 
 	cmp rax, syscallcount

kernel-src/sys/syscalls/fork.c

@@ -0,0 +1,63 @@
+#include <kernel/syscalls.h>
+#include <kernel/scheduler.h>
+#include <errno.h>
+#include <kernel/file.h>
+#include <kernel/interrupt.h>
+
+#include <logging.h>
+syscallret_t syscall_fork(context_t *ctx) {
+	syscallret_t ret = {
+		.ret = -1,
+		.errno = 0
+	};
+
+	proc_t *proc = _cpu()->thread->proc;
+	proc_t *nproc = sched_newproc();
+	if (nproc == NULL) {
+		ret.errno = ENOMEM;
+		goto cleanup;
+	}
+
+	thread_t *nthread = sched_newthread((void *)CTX_IP(ctx), 16 * PAGE_SIZE, 1, nproc, (void *)CTX_SP(ctx));
+	if (nthread == NULL) {
+		ret.errno = ENOMEM;
+		goto cleanup;
+	}
+
+	nthread->vmmctx = vmm_fork(_cpu()->thread->vmmctx);
+
+	if (nthread->vmmctx == NULL) {
+		ret.errno = ENOMEM;
+		goto cleanup;
+	}
+
+	ret.errno = fd_clone(nproc);
+	if (ret.errno)
+		goto cleanup;
+
+	bool intstate = interrupt_set(false);
+	spinlock_acquire(&proc->lock);
+
+	nproc->parent = proc;
+	nproc->sibling = proc->child;
+	proc->child = nproc;
+
+	spinlock_release(&proc->lock);
+	interrupt_set(intstate);
+
+	nproc->umask = _cpu()->thread->proc->umask;
+	nproc->root = sched_getroot();
+	nproc->cwd = sched_getcwd();
+
+	ARCH_CONTEXT_THREADSAVE(nthread, ctx);
+
+	CTX_RET(&nthread->context) = 0;
+	CTX_ERRNO(&nthread->context) = 0;
+
+	ret.ret = nproc->pid;
+
+	sched_queue(nthread);
+
+	cleanup:
+	return ret;
+}

patches/mlibc/jinx-working-patch.patch

@@ -133,10 +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..dc6bd0e
+index 0000000..3961e7f
 --- /dev/null
 +++ mlibc-workdir/sysdeps/astral/generic/generic.cpp
-@@ -0,0 +1,178 @@
+@@ -0,0 +1,185 @@
 +#include <bits/ensure.h>
 +#include <mlibc/debug.hpp>
 +#include <mlibc/all-sysdeps.hpp>
@@ -200,6 +200,13 @@ index 0000000..dc6bd0e
 +		return 0;
 +	}
 +
++	int sys_fork(pid_t *pid) {
++		long ret = 0;
++		long error = syscall(SYSCALL_FORK, &ret);
++		*pid = ret;
++		return error;
++	}
++
 +	int sys_stat(fsfd_target fsfdt, int fd, const char *path, int flags, struct stat *statbuf) {
 +		long ret;
 +		switch (fsfdt) {
@@ -334,10 +341,10 @@ 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..fde482a
+index 0000000..16c462d
 --- /dev/null
 +++ mlibc-workdir/sysdeps/astral/include/astral/syscall.h
-@@ -0,0 +1,34 @@
+@@ -0,0 +1,35 @@
 +#ifndef _SYSCALL_H_INCLUDE
 +#define _SYSCALL_H_INCLUDE
 +
@@ -352,6 +359,7 @@ index 0000000..fde482a
 +#define SYSCALL_GETPID 8
 +#define SYSCALL_FSTAT 9
 +#define SYSCALL_FSTATAT 10
++#define SYSCALL_FORK 11
 +
 +#include <stddef.h>
 +#include <stdint.h>