gems-kernel/source/THIRDPARTY/xnu/bsd/kern/kern_overrides.c
2024-06-03 11:29:39 -05:00

297 lines
9.7 KiB
C

/*
* Copyright (c) 2013 Apple Computer, Inc. All rights reserved.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. The rights granted to you under the License
* may not be used to create, or enable the creation or redistribution of,
* unlawful or unlicensed copies of an Apple operating system, or to
* circumvent, violate, or enable the circumvention or violation of, any
* terms of an Apple operating system software license agreement.
*
* Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/proc_internal.h>
#include <sys/proc.h>
#include <sys/kauth.h>
#include <sys/unistd.h>
#include <sys/priv.h>
#include <mach/mach_types.h>
#include <mach/vm_param.h>
#include <kern/task.h>
#include <kern/locks.h>
#include <kern/assert.h>
#include <kern/sched_prim.h>
#include <sys/kern_overrides.h>
#include <sys/bsdtask_info.h>
#include <sys/kdebug.h>
#include <sys/sysproto.h>
#include <sys/msgbuf.h>
#include <sys/kern_memorystatus.h>
/* Mutex for global system override state */
static LCK_GRP_DECLARE(sys_override_mtx_grp, "system_override");
static LCK_MTX_DECLARE(sys_override_lock, &sys_override_mtx_grp);
/*
* Assertion counts for system properties (add new ones for each new mechanism)
*
* The assertion count management for system overrides is as follows:
*
* - All assertion counts are protected by the sys_override_lock.
*
* - Each caller of system_override() increments the assertion count for the
* mechanism it specified in the flags. The caller then blocks for the
* timeout specified in the system call.
*
* - At the end of the timeout, the caller thread wakes up and decrements the
* assertion count for the mechanism it originally took an assertion on.
*
* - If another caller calls the system_override() to disable the override
* for a mechanism, it simply disables the mechanism without changing any
* assertion counts. That way, the assertion counts are properly balanced.
*
* One thing to note is that a SYS_OVERRIDE_DISABLE disables the overrides
* for a mechanism irrespective of how many clients requested that override.
* That makes the implementation simpler and avoids keeping a lot of process
* specific state in the kernel.
*
*/
static int64_t io_throttle_assert_cnt;
static int64_t cpu_throttle_assert_cnt;
static int64_t fast_jetsam_assert_cnt;
/* Wait Channel for system override */
static uint64_t sys_override_wait;
/* Helper routines */
static void system_override_begin(uint64_t flags);
static void system_override_end(uint64_t flags);
static void system_override_abort(uint64_t flags);
static void system_override_callouts(uint64_t flags, boolean_t enable_override);
static __attribute__((noinline)) int PROCESS_OVERRIDING_SYSTEM_DEFAULTS(uint64_t timeout);
/* system call implementation */
int
system_override(__unused struct proc *p, struct system_override_args * uap, __unused int32_t *retval)
{
uint64_t timeout = uap->timeout;
uint64_t flags = uap->flags;
int error = 0;
/* Check credentials for caller. Only entitled processes are allowed to make this call. */
if ((error = priv_check_cred(kauth_cred_get(), PRIV_SYSTEM_OVERRIDE, 0))) {
goto out;
}
/* Check to see if sane flags are specified. */
if ((flags & ~SYS_OVERRIDE_FLAGS_MASK) != 0) {
error = EINVAL;
goto out;
}
lck_mtx_lock(&sys_override_lock);
if (flags & SYS_OVERRIDE_DISABLE) {
flags &= ~SYS_OVERRIDE_DISABLE;
system_override_abort(flags);
} else {
system_override_begin(flags);
error = PROCESS_OVERRIDING_SYSTEM_DEFAULTS(timeout);
system_override_end(flags);
}
lck_mtx_unlock(&sys_override_lock);
out:
return error;
}
/*
* Helper routines for enabling/disabling system overrides for various mechanisms.
* These routines should be called with the sys_override_lock held. Each subsystem
* which is hooked into the override service provides two routines:
*
* - void sys_override_foo_init(void);
* Routine to initialize the subsystem or the data needed for the override to work.
* This routine is optional and if a subsystem needs it, it should be invoked from
* init_system_override().
*
* - void sys_override_foo(boolean_t enable_override);
* Routine to enable/disable the override mechanism for that subsystem. A value of
* true indicates that the mechanism should be overridden and the special behavior
* should begin. A false value indicates that the subsystem should return to default
* behavior. This routine is mandatory and should be invoked as part of the helper
* routines if the flags passed in the syscall match the subsystem. Also, this
* routine should preferably be idempotent.
*/
static void
system_override_callouts(uint64_t flags, boolean_t enable_override)
{
switch (flags) {
case SYS_OVERRIDE_IO_THROTTLE:
if (enable_override) {
KERNEL_DEBUG_CONSTANT(FSDBG_CODE(DBG_THROTTLE, IO_THROTTLE_DISABLE) | DBG_FUNC_START,
proc_getpid(current_proc()), 0, 0, 0, 0);
} else {
KERNEL_DEBUG_CONSTANT(FSDBG_CODE(DBG_THROTTLE, IO_THROTTLE_DISABLE) | DBG_FUNC_END,
proc_getpid(current_proc()), 0, 0, 0, 0);
}
sys_override_io_throttle(enable_override);
break;
case SYS_OVERRIDE_CPU_THROTTLE:
if (enable_override) {
KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_CPU_THROTTLE_DISABLE) | DBG_FUNC_START,
proc_getpid(current_proc()), 0, 0, 0, 0);
} else {
KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_CPU_THROTTLE_DISABLE) | DBG_FUNC_END,
proc_getpid(current_proc()), 0, 0, 0, 0);
}
sys_override_cpu_throttle(enable_override);
break;
case SYS_OVERRIDE_FAST_JETSAM:
if (enable_override) {
KERNEL_DEBUG_CONSTANT(BSDDBG_CODE(DBG_BSD_MEMSTAT, BSD_MEMSTAT_FAST_JETSAM) | DBG_FUNC_START,
proc_getpid(current_proc()), 0, 0, 0, 0);
} else {
KERNEL_DEBUG_CONSTANT(BSDDBG_CODE(DBG_BSD_MEMSTAT, BSD_MEMSTAT_FAST_JETSAM) | DBG_FUNC_END,
proc_getpid(current_proc()), 0, 0, 0, 0);
}
#if CONFIG_JETSAM
memorystatus_fast_jetsam_override(enable_override);
#endif /* CONFIG_JETSAM */
break;
default:
panic("Unknown option to system_override_callouts(): %llu", flags);
}
}
/*
* system_override_begin(uint64_t flags)
*
* Routine to start a system override if the assertion count
* transitions from 0->1 for a specified mechanism.
*/
static void
system_override_begin(uint64_t flags)
{
lck_mtx_assert(&sys_override_lock, LCK_MTX_ASSERT_OWNED);
if (flags & SYS_OVERRIDE_IO_THROTTLE) {
if (io_throttle_assert_cnt == 0) {
system_override_callouts(SYS_OVERRIDE_IO_THROTTLE, true);
}
io_throttle_assert_cnt++;
}
if (flags & SYS_OVERRIDE_CPU_THROTTLE) {
if (cpu_throttle_assert_cnt == 0) {
system_override_callouts(SYS_OVERRIDE_CPU_THROTTLE, true);
}
cpu_throttle_assert_cnt++;
}
if (flags & SYS_OVERRIDE_FAST_JETSAM) {
if (fast_jetsam_assert_cnt == 0) {
system_override_callouts(SYS_OVERRIDE_FAST_JETSAM, true);
}
fast_jetsam_assert_cnt++;
}
}
/*
* system_override_end(uint64_t flags)
*
* Routine to end a system override if the assertion count
* transitions from 1->0 for a specified mechanism.
*/
static void
system_override_end(uint64_t flags)
{
lck_mtx_assert(&sys_override_lock, LCK_MTX_ASSERT_OWNED);
if (flags & SYS_OVERRIDE_IO_THROTTLE) {
assert(io_throttle_assert_cnt > 0);
io_throttle_assert_cnt--;
if (io_throttle_assert_cnt == 0) {
system_override_callouts(SYS_OVERRIDE_IO_THROTTLE, false);
}
}
if (flags & SYS_OVERRIDE_CPU_THROTTLE) {
assert(cpu_throttle_assert_cnt > 0);
cpu_throttle_assert_cnt--;
if (cpu_throttle_assert_cnt == 0) {
system_override_callouts(SYS_OVERRIDE_CPU_THROTTLE, false);
}
}
if (flags & SYS_OVERRIDE_FAST_JETSAM) {
assert(fast_jetsam_assert_cnt > 0);
fast_jetsam_assert_cnt--;
if (fast_jetsam_assert_cnt == 0) {
system_override_callouts(SYS_OVERRIDE_FAST_JETSAM, false);
}
}
}
/*
* system_override_abort(uint64_t flags)
*
* Routine to abort a system override (if one was active)
* irrespective of the assertion counts and number of blocked
* requestors.
*/
static void
system_override_abort(uint64_t flags)
{
lck_mtx_assert(&sys_override_lock, LCK_MTX_ASSERT_OWNED);
if ((flags & SYS_OVERRIDE_IO_THROTTLE) && (io_throttle_assert_cnt > 0)) {
system_override_callouts(SYS_OVERRIDE_IO_THROTTLE, false);
}
if ((flags & SYS_OVERRIDE_CPU_THROTTLE) && (cpu_throttle_assert_cnt > 0)) {
system_override_callouts(SYS_OVERRIDE_CPU_THROTTLE, false);
}
if ((flags & SYS_OVERRIDE_FAST_JETSAM) && (fast_jetsam_assert_cnt > 0)) {
system_override_callouts(SYS_OVERRIDE_FAST_JETSAM, false);
}
}
static __attribute__((noinline)) int
PROCESS_OVERRIDING_SYSTEM_DEFAULTS(uint64_t timeout)
{
struct timespec ts;
ts.tv_sec = timeout / NSEC_PER_SEC;
ts.tv_nsec = timeout - ((long)ts.tv_sec * NSEC_PER_SEC);
int error = msleep((caddr_t)&sys_override_wait, &sys_override_lock, PRIBIO | PCATCH, "system_override", &ts);
/* msleep returns EWOULDBLOCK if timeout expires, treat that as success */
return (error == EWOULDBLOCK) ? 0 : error;
}