81 lines
6.2 KiB
Markdown
81 lines
6.2 KiB
Markdown
# SysABI
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Syscalls are a way for programms to communicate with the kernel.
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To perform a syscall, you need to populate the following registers:
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| Register | Value |
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|----------|-----------------|
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| rax | The syscalls ID |
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| rdi | Argument 1 |
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| rsi | Argument 2 |
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| rdx | Argument 3 |
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| rcx | Argument 4 |
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---
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The following calls should be implemented to some degree in noxos 1.0.
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# Categories
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## Files
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| ID | Name | Description | Arg1 | Arg2 | Arg3 | Arg4 | Result | Status |
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|--------|--------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------|--------|------|-------------|--------|-------------|
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| 0x0101 | `nx_fopen` | Opens the file at the _len_ bytes long path _path_ and writes a file descriptor to the referenced file into _fd_ (which needs to be a pointer). | path | len | *fd | | status | Implemented |
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| 0x0102 | `nx_fclose` | Closes the file which is indicated by descriptor _fd_. This should always be called, otherwise the OS will have to unload files without knowledge of usage. | fd | | | | status | Implemented |
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| 0x0103 | `nx_fread` | Reads at most _n_ bytes from a file given as descriptor _fd_ and at a specific position _offset_ into a given memory region _mem_. | fd | offset | mem | n | status | Implemented |
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| 0x0104 | `nx_fwrite` | Writes _n_ bytes from a given memory region _mem_ into the file referenced by _fd_ at the given position _offset_, not inserting but either overwriting existing content or appending to the file. | fd | offset | mem | n | status | Implemented |
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| 0x0105 | `nx_fdelete` | Completely delete the file or folder at a given path _path_, which is _len_ bytes long. | path | len | | | status | Implemented |
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| 0x0106 | `nx_flist` | List all files and/or directories at the _len_ bytes long path _path_ and write their NULL-separated names into _mem_. When _mem_ is NULL, _needed_mem_ (which needs to be a pointer to an 32-bit integer) is filled with the appropriate value. | path | len | mem | *needed_mem | status | Implemented |
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| 0x0107 | `nx_finfo` | Writes the information about the files attribute _attr_ into mem. Types of attributes are described below. | fd | attr | mem | | status | N/A |
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**Note:** The _len_ argument of paths isn't used at the moment, rather than using _len_, _path_ needs to be Null-Terminated.
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## Memory
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| ID | Name | Description | Arg1 | Arg2 | Arg3 | Arg4 | Result | Status |
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|--------|-------------|-------------------------------------------------------------------------------------------------------------------------------------------------|------|------|-------|------|--------|-------------|
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| 0x0201 | `nx_mmap` | Maps _n_ 4KB pages to address _addr_. You can provide a bitmap of flags with the _flags_ argument. Which flags can be used, is described below. | addr | n | flags | | status | Implemented |
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| 0x0202 | `nx_munmap` | Unmaps _n_ 4KB pages at address _addr_. | addr | n | | | status | Implemented |
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## Processes
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| ID | Name | Description | Arg1 | Arg2 | Arg3 | Arg4 | Result | Status |
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|-----|------|-------------|------|------|------|------|--------|--------|
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## Runtime / Dynamic Linker
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| ID | Name | Description | Arg1 | Arg2 | Arg3 | Arg4 | Result | Status |
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|-----|------|-------------|------|------|------|------|--------|--------|
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## Compatibility & Safety
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| ID | Name | Description | Arg1 | Arg2 | Arg3 | Arg4 | Result | Status |
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|-----|------|-------------|------|------|------|------|--------|--------|
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## Kernel
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The kernel syscalls can only be called from the kernels main process [link to processing article needed].
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If another process calls them, they will just return without doing anything.
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| ID | Name | Description | Arg1 | Arg2 | Arg3 | Arg4 | Result | Status |
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|-----|------|-------------|------|------|------|------|--------|--------|
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---
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## Appendixes
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### Types of file attributes
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| ID | Name | Description | Data Type | Status |
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|-----|---------------|--------------------------------------------|-----------|--------|
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| 0 | `permissions` | Who has what permission to access the file | uint16_t | N/A |
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| 1 | `size` | The files size in bytes | uint64_t | N/A |
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### Memory mapping flags
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| Bit | Name | Description |
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|-----|-----------|-------------------------------------------|
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| 0 | `write` | Enables write access to the mapped pages. |
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| 1 | `no_exec` | Prevents execution of the mapped pages. |
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