x86-64 syscalls

A program here runs as a Linux program, so everything outside its own memory happens through syscall. Put the call number in rax, the arguments in rdi, rsi, rdx, r10, r8 and r9, and read the result from rax. A result between -1 and -4095 is an error code. rcx and r11 do not survive the call.

The ones to start with

1 - write waits

Writes rdx bytes from the buffer at rsi to the file descriptor in rdi, and returns how many it wrote. Descriptor 1 is standard output and 2 is standard error, so this is how a program prints.

rdi

file descriptor

rsi

buffer (read by the kernel)

rdx

byte count

0 - read waits

Reads up to rdx bytes from the file descriptor in rdi into the buffer at rsi, and returns how many it read. Descriptor 0 is standard input, so this is how a program reads what was typed. A return of 0 means end of input.

rdi

file descriptor

rsi

buffer (written by the kernel)

rdx

byte count

60 - exit

Ends the program with the status in rdi. It never returns, and a program that reaches the end of its code without calling it runs into whatever bytes follow.

rdi

status

231 - exit_group

Ends every thread of the program with the status in rdi. For a program with one thread it is exit.

rdi

status

2 - open waits

Opens the path at rdi with the flags in rsi and, when creating, the mode in rdx. Returns a file descriptor.

rdi

path

rsi

open flags

rdx

mode

3 - close waits

Closes the file descriptor in rdi.

rdi

file descriptor

8 - lseek

Moves the read and write position of the descriptor in rdi to the offset in rsi, interpreted according to rdx, and returns the new position.

rdi

file descriptor

rsi

offset

rdx

whence

5 - fstat

Fills the structure at rsi with what is known about the descriptor in rdi, including its size.

rdi

file descriptor

rsi

o_stat

12 - brk

Moves the end of the data segment to the address in rdi, which is the oldest way to ask for more memory. Called with 0 it returns where the segment currently ends.

rdi

value

9 - mmap

Maps memory: the length in rsi, the protection in rdx, the flags in r10. An anonymous private mapping is how a program asks for a block of memory it can write to.

rdi

pointer

rsi

size

rdx

protection flags

r10

mapping flags

file descriptor

offset

11 - munmap

Unmaps the mapping of rsi bytes at the address in rdi.

rdi

pointer

rsi

size

35 - nanosleep waits

Sleeps for the interval at rdi, a pair of seconds and nanoseconds.

rdi

i_time

rsi

o_time

228 - clock_gettime

Writes the time of the clock named in rdi into the structure at rsi.

rdi

clock

rsi

timespec

39 - getpid

Returns the process id.

Everything this emulator implements

Those syscalls are what the emulator implements, anything missing returns -ENOSYS.

rax	Call	Arguments
4	stat	rdi pathrsi o_stat
6	lstat	rdi pathrsi o_stat
7	poll	rdi valuersi valuerdx value
10	mprotect	rdi pointerrsi sizerdx protection flags
13	rt_sigaction	rdi signalrsi i_handrdx o_handr10 byte count
14	rt_sigprocmask	rdi sighowrsi i_sigsetrdx o_sigsetr10 byte count
16	ioctl	rdi valuersi valuerdx value
17	pread	rdi file descriptorrsi buffer (written by the kernel)rdx byte countr10 offset
18	pwrite	rdi file descriptorrsi buffer (read by the kernel)rdx byte countr10 offset
19	readv	rdi file descriptorrsi iovec array (written)rdx byte count
20	writev	rdi file descriptorrsi iovec array (read)rdx byte count
21	access	rdi pathrsi accmode
22	pipe	rdi o_pfds
23	select	rdi intrsi io_fdsetrdx io_fdsetr10 io_fdsetr8 io_timev
24	sched_yield
25	mremap	rdi valuersi valuerdx valuer10 valuer8 value
26	msync	rdi valuersi valuerdx value
28	madvise	rdi valuersi valuerdx value
32	dup	rdi file descriptor
33	dup2	rdi file descriptorrsi int
34	pause
36	getitimer	rdi valuersi value
37	alarm	rdi int
38	setitimer	rdi valuersi valuerdx value
40	sendfile	rdi valuersi valuerdx valuer10 value
41	socket	rdi familyrsi socktyperdx int
42	connect	rdi file descriptorrsi i_addrrdx addrlen
43	accept	rdi file descriptorrsi o_addrrdx long
44	sendto	rdi file descriptorrsi buffer (read by the kernel)rdx sizer10 intr8 i_addrr9 addrlen
45	recvfrom	rdi file descriptorrsi buffer (written by the kernel)rdx sizer10 intr8 o_addrr9 long
46	sendmsg	rdi valuersi valuerdx value
47	recvmsg	rdi valuersi valuerdx value
48	shutdown	rdi valuersi value
49	bind	rdi file descriptorrsi i_addrrdx addrlen
50	listen	rdi file descriptorrsi un
51	getsockname	rdi file descriptorrsi o_addrrdx long
52	getpeername	rdi file descriptorrsi o_addrrdx long
53	socketpair	rdi familyrsi socktyperdx intr10 o_pfds
54	setsockopt	rdi valuersi valuerdx valuer10 valuer8 value
55	getsockopt	rdi valuersi valuerdx valuer10 valuer8 value
56	clone	rdi cloneflagsrsi pointerrdx pointerr10 pointerr8 pointerr9 pointer
57	fork
58	vfork
59	execve	rdi valuersi valuerdx value
61	wait4	rdi process idrsi o_wstatusrdx waitflagsr10 o_rusage
62	kill	rdi process idrsi signal
63	uname	rdi value
72	fcntl	rdi file descriptorrsi wat_fcntlrdx un
73	flock	rdi valuersi value
74	fsync	rdi file descriptor
75	fdatasync	rdi file descriptor
76	truncate	rdi stringrsi offset
77	ftruncate	rdi file descriptorrsi offset
79	getcwd	rdi buffer (written by the kernel)rsi byte count
80	chdir	rdi path
81	fchdir	rdi file descriptor
82	rename	rdi pathrsi path
83	mkdir	rdi pathrsi mode
84	rmdir	rdi path
85	creat	rdi pathrsi mode
86	link	rdi pathrsi path
87	unlink	rdi path
88	symlink	rdi pathrsi path
89	readlink	rdi pathrsi buffer (written by the kernel)rdx byte count
90	chmod	rdi pathrsi mode
91	fchmod	rdi file descriptorrsi uid
92	chown	rdi pathrsi uidrdx gid
93	fchown	rdi file descriptorrsi uidrdx gid
94	lchown	rdi pathrsi uidrdx gid
95	umask	rdi mode
96	gettimeofday	rdi valuersi value
97	getrlimit	rdi resourcersi o_rlimit
98	getrusage	rdi valuersi value
99	sysinfo	rdi value
100	times	rdi value
102	getuid
104	getgid
105	setuid	rdi uid
106	setgid	rdi gid
107	geteuid
108	getegid
109	setpgid	rdi valuersi value
110	getppid
111	getpgrp
112	setsid
113	setreuid	rdi uidrsi uid
114	setregid	rdi gidrsi gid
115	getgroups	rdi valuersi value
116	setgroups	rdi valuersi value
117	setresuid	rdi uidrsi uidrdx uid
118	getresuid	rdi valuersi valuerdx value
119	setresgid	rdi gidrsi gidrdx gid
120	getresgid	rdi valuersi valuerdx value
121	getpgid	rdi process id
124	getsid	rdi value
127	rt_sigpending	rdi value
130	rt_sigsuspend	rdi i_sigsetrsi byte count
131	sigaltstack	rdi valuersi value
132	utime	rdi valuersi value
133	mknod	rdi valuersi valuerdx value
137	statfs	rdi valuersi value
138	fstatfs	rdi valuersi value
140	getpriority	rdi valuersi value
141	setpriority	rdi valuersi valuerdx value
142	sched_set_param	rdi valuersi value
143	sched_get_param	rdi valuersi value
144	sched_set_scheduler	rdi valuersi valuerdx value
145	sched_get_scheduler	rdi value
146	sched_get_priority_max	rdi value
147	sched_get_priority_min	rdi value
157	prctl	rdi valuersi valuerdx valuer10 valuer8 value
158	arch_prctl	rdi valuersi value
160	setrlimit	rdi resourcersi i_rlimit
161	chroot	rdi path
162	sync
165	mount	rdi stringrsi stringrdx msflagsr10 pointerr8 un
186	gettid
200	tkill	rdi process idrsi signal
202	futex	rdi valuersi valuerdx valuer10 valuer8 valuer9 value
203	sched_set_affinity	rdi valuersi valuerdx value
204	sched_get_affinity	rdi valuersi valuerdx value
213	epoll_create	rdi value
217	getdents	rdi valuersi valuerdx value
218	set_tid_address	rdi value
221	fadvise	rdi valuersi valuerdx valuer10 value
227	clock_settime	rdi valuersi value
229	clock_getres	rdi valuersi value
230	clock_nanosleep	rdi clockrsi intrdx i_timer10 o_time
232	epoll_wait	rdi valuersi valuerdx valuer10 value
233	epoll_ctl	rdi valuersi valuerdx valuer10 value
234	tgkill	rdi valuersi valuerdx value
235	utimes	rdi valuersi value
257	openat	rdi directory descriptorrsi stringrdx open flagsr10 mode
258	mkdirat	rdi directory descriptorrsi pathrdx mode
259	mknodat	rdi valuersi valuerdx valuer10 value
260	fchownat	rdi directory descriptorrsi pathrdx uidr10 gidr8 atflags
261	futimesat	rdi valuersi valuerdx value
262	fstatat	rdi directory descriptorrsi pathrdx o_statr10 atflags
263	unlinkat	rdi directory descriptorrsi pathrdx atflags
264	renameat	rdi directory descriptorrsi pathrdx directory descriptorr10 path
265	linkat	rdi directory descriptorrsi pathrdx directory descriptorr10 pathr8 atflags
266	symlinkat	rdi pathrsi directory descriptorrdx path
267	readlinkat	rdi directory descriptorrsi stringrdx buffer (written by the kernel)r10 byte count
268	fchmodat	rdi directory descriptorrsi pathrdx mode
269	faccessat	rdi directory descriptorrsi pathrdx accmode
270	pselect6	rdi valuersi valuerdx valuer10 valuer8 valuer9 value
271	ppoll	rdi valuersi valuerdx valuer10 valuer8 value
273	set_robust_list	rdi valuersi value
274	get_robust_list	rdi valuersi valuerdx value
280	utimensat	rdi directory descriptorrsi pathrdx o_time2r10 atflags
281	epoll_pwait	rdi valuersi valuerdx valuer10 valuer8 valuer9 value
288	accept4	rdi file descriptorrsi o_addrrdx longr10 sockflags
291	epoll_create1	rdi value
292	dup3	rdi file descriptorrsi intrdx open flags
293	pipe2	rdi o_pfdsrsi open flags
295	preadv	rdi file descriptorrsi iovec array (written)rdx byte countr10 offset
296	pwritev	rdi file descriptorrsi iovec array (read)rdx byte countr10 offset
299	recvmmsg	rdi valuersi valuerdx valuer10 valuer8 value
302	prlimit	rdi process idrsi resourcerdx i_rlimitr10 o_rlimit
307	sendmmsg	rdi valuersi valuerdx valuer10 value
316	renameat2	rdi directory descriptorrsi pathrdx directory descriptorr10 pathr8 atflags
318	getrandom	rdi buffer (written by the kernel)rsi byte countrdx int
327	preadv2	rdi file descriptorrsi iovec array (written)rdx byte countr10 offsetr8 int
328	pwritev2	rdi file descriptorrsi iovec array (read)rdx byte countr10 offsetr8 int
436	close_range	rdi valuersi valuerdx value
439	faccessat2	rdi directory descriptorrsi pathrdx accmoder10 atflags
441	epoll_pwait2	rdi valuersi valuerdx valuer10 valuer8 valuer9 value