#include <os/atomic_private.h>
#include <kern/cpu_data.h>
#include <kern/kalloc.h>
#include <kern/simple_lock.h> // hw_wait_while_equals
#include <libkern/libkern.h>
#include <sys/sysctl.h>
#include "ubsan.h"
static const size_t ubsan_log_size = 2048;
struct ubsan_violation ubsan_log[ubsan_log_size];
_Atomic size_t ubsan_log_head = 0;
_Atomic size_t ubsan_log_tail = 0;
_Atomic size_t ubsan_log_next = 0;
static const bool ubsan_logging = true;
static inline size_t
next_entry(size_t x)
{
return (x + 1) % ubsan_log_size;
}
void
ubsan_log_append(struct ubsan_violation *violation)
{
if (!ubsan_logging) {
return;
}
size_t i, e, n;
disable_preemption();
os_atomic_rmw_loop(&ubsan_log_next, i, n, relaxed, {
n = next_entry(i);
if (n == os_atomic_load(&ubsan_log_tail, acquire)) {
enable_preemption();
return;
}
});
ubsan_log[i] = *violation;
os_atomic_thread_fence(release);
again:
os_atomic_rmw_loop(&ubsan_log_head, e, n, relaxed, {
if (e != i) {
os_atomic_rmw_loop_give_up({
hw_wait_while_equals((void **)&ubsan_log_head, (void *)e);
goto again;
});
}
});
enable_preemption();
}
static int
sysctl_ubsan_log_dump SYSCTL_HANDLER_ARGS
{
#pragma unused(oidp, arg1, arg2)
const size_t sz = ubsan_log_size * 256;
size_t head, tail;
head = os_atomic_load(&ubsan_log_head, relaxed);
os_atomic_thread_fence(seq_cst);
tail = os_atomic_load(&ubsan_log_tail, relaxed);
char *buf;
size_t n = 0;
int err;
if (tail == head) {
return 0;
}
buf = kheap_alloc(KHEAP_TEMP, sz, Z_WAITOK | Z_ZERO);
if (!buf) {
return 0;
}
for (size_t i = tail; i != head; i = next_entry(i)) {
n += ubsan_format(&ubsan_log[i], buf + n, sz - n);
}
err = SYSCTL_OUT(req, buf, n);
kheap_free(KHEAP_TEMP, buf, sz);
return err;
}
static int
sysctl_ubsan_log_entries SYSCTL_HANDLER_ARGS
{
#pragma unused(oidp, arg1, arg2)
int ch, err, val;
size_t head, tail;
size_t nentries;
head = os_atomic_load(&ubsan_log_head, relaxed);
os_atomic_thread_fence(seq_cst);
tail = os_atomic_load(&ubsan_log_tail, relaxed);
if (head >= tail) {
nentries = head - tail;
} else {
nentries = ubsan_log_size - (tail - head + 1);
}
err = sysctl_io_number(req, nentries, sizeof(nentries), &val, &ch);
if (err == 0 && ch) {
if (val != 0) {
err = EINVAL;
} else {
os_atomic_store(&ubsan_log_tail, head, relaxed);
}
}
return err;
}
SYSCTL_DECL(ubsan);
SYSCTL_NODE(_kern, OID_AUTO, ubsan, CTLFLAG_RW | CTLFLAG_LOCKED, 0, "");
SYSCTL_COMPAT_UINT(_kern_ubsan, OID_AUTO, logsize, CTLFLAG_RD, NULL, (unsigned)ubsan_log_size, "");
SYSCTL_PROC(_kern_ubsan, OID_AUTO, logentries,
CTLTYPE_INT | CTLFLAG_RW,
0, 0, sysctl_ubsan_log_entries, "I", "");
SYSCTL_PROC(_kern_ubsan, OID_AUTO, log,
CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MASKED,
0, 0, sysctl_ubsan_log_dump, "A", "");