5647 - experimental support for swapping OS

1 files changed, 68 insertions, 0 deletions

diff --git a/049init.linux b/049init.linux
new file mode 100644
index 00000000..4dcb77be
--- /dev/null
+++ b/049init.linux
@@ -0,0 +1,68 @@
+# Some OS-specific preliminaries for Linux.
+
+# Memory layout
+#
+#          0 - 0x08047ffff - reserved for the kernel
+# 0x08048000 - 0xbffffffff - available for user programs
+# 0xc0000000 - 0xfffffffff - reserved for the kernel
+== code 0x09000000
+== data 0x0a000000
+
+# Syscalls
+#
+# We don't have libc, so we need to know Linux's precise syscall layout.
+== code
+
+# http://man7.org/linux/man-pages/man2/exit.2.html
+syscall_exit:  # status/ebx : int
+    b8/copy-to-eax 1/imm32
+    cd/syscall 0x80/imm8
+
+# http://man7.org/linux/man-pages/man2/read.2.html
+syscall_read:  # fd/ebx : int, buf/ecx : address, size/edx : int -> nbytes-or-error/eax : int
+    b8/copy-to-eax 3/imm32
+    cd/syscall 0x80/imm8
+    c3/return
+
+# http://man7.org/linux/man-pages/man2/write.2.html
+syscall_write:  # fd/ebx : int, buf/ecx : address, size/edx : int -> nbytes-or-error/eax : int
+    b8/copy-to-eax 4/imm32
+    cd/syscall 0x80/imm8
+    c3/return
+
+# http://man7.org/linux/man-pages/man2/open.2.html
+syscall_open:  # filename/ebx : (address null-terminated-string), flags/ecx : int -> fd-or-error/eax : int
+    b8/copy-to-eax 5/imm32
+    cd/syscall 0x80/imm8
+    c3/return
+
+# http://man7.org/linux/man-pages/man2/close.2.html
+syscall_close:  # fd/ebx : int -> status/eax
+    b8/copy-to-eax 6/imm32
+    cd/syscall 0x80/imm8
+    c3/return
+
+# http://man7.org/linux/man-pages/man2/creat.2.html
+syscall_creat:  # filename/ebx : (address null-terminated-string) -> fd-or-error/eax : int
+    b8/copy-to-eax 8/imm32
+    cd/syscall 0x80/imm8
+    c3/return
+
+# http://man7.org/linux/man-pages/man2/unlink.2.html
+syscall_unlink:  # filename/ebx : (address null-terminated-string) -> status/eax : int
+    b8/copy-to-eax 0xa/imm32
+    cd/syscall 0x80/imm8
+    c3/return
+
+# http://man7.org/linux/man-pages/man2/rename.2.html
+syscall_rename:  # source/ebx : (address null-terminated-string), dest/ecx : (address null-terminated-string) -> status/eax : int
+    b8/copy-to-eax 0x26/imm32
+    cd/syscall 0x80/imm8
+    c3/return
+
+# https://github.com/torvalds/linux/blob/fa121bb3fed6313b1f0af23952301e06cf6d32ed/mm/nommu.c#L1352
+syscall_mmap:  # arg/ebx : (address mmap_arg_struct) -> status/eax : int
+    # the important thing: ebx+4 contains the 32-bit size to be allocated
+    b8/copy-to-eax 0x5a/imm32
+    cd/syscall 0x80/imm8
+    c3/return