Hello!
I also have this issue!
I believe it's a kernel flag to allow read/write of dev/mem
Anyway of changing that without compiling a custom kernel?
Strace log
root@orangepi5-plus:~# strace gpio readall
execve("/usr/local/bin/gpio", ["gpio", "readall"], 0xffffd664ff88 /* 21 vars */) = 0
brk(NULL) = 0xaaaac110a000
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xffff8f698000
faccessat(AT_FDCWD, "/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
newfstatat(3, "", {st_mode=S_IFREG|0644, st_size=99325, ...}, AT_EMPTY_PATH) = 0
mmap(NULL, 99325, PROT_READ, MAP_PRIVATE, 3, 0) = 0xffff8f64b000
close(3) = 0
openat(AT_FDCWD, "/usr/local/lib/libwiringPi.so", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0\267\0\1\0\0\0\0\0\0\0\0\0\0\0"..., 832) = 832
newfstatat(3, "", {st_mode=S_IFREG|0755, st_size=154496, ...}, AT_EMPTY_PATH) = 0
mmap(NULL, 266552, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xffff8f609000
mmap(0xffff8f610000, 201016, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0) = 0xffff8f610000
munmap(0xffff8f609000, 28672) = 0
munmap(0xffff8f642000, 33080) = 0
mprotect(0xffff8f627000, 61440, PROT_NONE) = 0
mmap(0xffff8f636000, 40960, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x16000) = 0xffff8f636000
mmap(0xffff8f640000, 4408, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xffff8f640000
close(3) = 0
openat(AT_FDCWD, "/usr/local/lib/libwiringPiDev.so", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0\267\0\1\0\0\0\0\0\0\0\0\0\0\0"..., 832) = 832
newfstatat(3, "", {st_mode=S_IFREG|0755, st_size=37016, ...}, AT_EMPTY_PATH) = 0
mmap(NULL, 167040, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xffff8f5e7000
mmap(0xffff8f5f0000, 101504, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0) = 0xffff8f5f0000
munmap(0xffff8f5e7000, 36864) = 0
munmap(0xffff8f609000, 27776) = 0
mprotect(0xffff8f5f6000, 61440, PROT_NONE) = 0
mmap(0xffff8f605000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x5000) = 0xffff8f605000
mmap(0xffff8f607000, 7296, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xffff8f607000
close(3) = 0
openat(AT_FDCWD, "/lib/aarch64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0\267\0\1\0\0\0\340u\2\0\0\0\0\0"..., 832) = 832
newfstatat(3, "", {st_mode=S_IFREG|0644, st_size=1641496, ...}, AT_EMPTY_PATH) = 0
mmap(NULL, 1810024, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xffff8f436000
mmap(0xffff8f440000, 1744488, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0) = 0xffff8f440000
munmap(0xffff8f436000, 40960) = 0
munmap(0xffff8f5ea000, 24168) = 0
mprotect(0xffff8f5c9000, 61440, PROT_NONE) = 0
mmap(0xffff8f5d8000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x188000) = 0xffff8f5d8000
mmap(0xffff8f5de000, 48744, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xffff8f5de000
close(3) = 0
openat(AT_FDCWD, "/lib/aarch64-linux-gnu/libm.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0\267\0\1\0\0\0\0\0\0\0\0\0\0\0"..., 832) = 832
newfstatat(3, "", {st_mode=S_IFREG|0644, st_size=551064, ...}, AT_EMPTY_PATH) = 0
mmap(NULL, 680048, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xffff8f399000
mmap(0xffff8f3a0000, 614512, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0) = 0xffff8f3a0000
munmap(0xffff8f399000, 28672) = 0
munmap(0xffff8f437000, 32880) = 0
mprotect(0xffff8f426000, 61440, PROT_NONE) = 0
mmap(0xffff8f435000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x85000) = 0xffff8f435000
close(3) = 0
openat(AT_FDCWD, "/lib/aarch64-linux-gnu/libcrypt.so.1", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0\267\0\1\0\0\0\20\25\0\0\0\0\0\0"..., 832) = 832
newfstatat(3, "", {st_mode=S_IFREG|0644, st_size=186296, ...}, AT_EMPTY_PATH) = 0
mmap(NULL, 348512, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xffff8f34a000
mmap(0xffff8f350000, 282976, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0) = 0xffff8f350000
munmap(0xffff8f34a000, 24576) = 0
munmap(0xffff8f396000, 37216) = 0
mprotect(0xffff8f37d000, 61440, PROT_NONE) = 0
mmap(0xffff8f38c000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x2c000) = 0xffff8f38c000
mmap(0xffff8f38e000, 29024, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xffff8f38e000
close(3) = 0
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xffff8f696000
set_tid_address(0xffff8f696b10) = 11233
set_robust_list(0xffff8f696b20, 24) = 0
rseq(0xffff8f6971e0, 0x20, 0, 0xd428bc00) = 0
mprotect(0xffff8f5d8000, 16384, PROT_READ) = 0
mprotect(0xffff8f38c000, 4096, PROT_READ) = 0
mprotect(0xffff8f435000, 4096, PROT_READ) = 0
mprotect(0xffff8f605000, 4096, PROT_READ) = 0
mprotect(0xffff8f636000, 4096, PROT_READ) = 0
mprotect(0xaaaaab06d000, 4096, PROT_READ) = 0
mprotect(0xffff8f69d000, 8192, PROT_READ) = 0
prlimit64(0, RLIMIT_STACK, NULL, {rlim_cur=8192*1024, rlim_max=RLIM64_INFINITY}) = 0
munmap(0xffff8f64b000, 99325) = 0
geteuid() = 0
getrandom("\x97\x05\x6a\x79\xe5\x03\x78\xac", 8, GRND_NONBLOCK) = 8
brk(NULL) = 0xaaaac110a000
brk(0xaaaac112b000) = 0xaaaac112b000
openat(AT_FDCWD, "/etc/orangepi-release", O_RDONLY) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/etc/armbian-release", O_RDONLY) = 3
newfstatat(3, "", {st_mode=S_IFREG|0644, st_size=464, ...}, AT_EMPTY_PATH) = 0
read(3, "# PLEASE DO NOT EDIT THIS FILE\nB"..., 4096) = 464
close(3) = 0
openat(AT_FDCWD, "/dev/mem", O_RDWR|O_SYNC|O_CLOEXEC) = 3 #ERROS HERE -dan
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_SHARED, 3, 0x300b000) = -1 EPERM (Operation not permitted)
write(2, "wiringPiSetup: mmap (GPIO) faile"..., 59wiringPiSetup: mmap (GPIO) failed: Operation not permitted
) = 59
exit_group(1) = ?
+++ exited with 1 +++
