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genode/repos/base-nova/src/core/pager.cc
Alexander Boettcher 9ab593e1b5 nova: provide system_control cap per cpu 
Issue #5009
2023-10-04 13:22:07 +02:00

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/*
* \brief Pager framework
* \author Norman Feske
* \author Sebastian Sumpf
* \author Alexander Boettcher
* \date 2010-01-25
*/
/*
* Copyright (C) 2010-2020 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU Affero General Public License version 3.
*/
/* Genode includes */
#include <rm_session/rm_session.h>
/* base-internal includes */
#include <base/internal/native_thread.h>
/* core includes */
#include <pager.h>
#include <platform.h>
#include <platform_thread.h>
#include <imprint_badge.h>
#include <cpu_thread_component.h>
#include <core_env.h>
/* NOVA includes */
#include <nova/syscalls.h>
#include <nova_util.h> /* map_local */
#include <nova/capability_space.h>
static bool verbose_oom = false;
using namespace Core;
using namespace Nova;
/**
* Pager threads - one thread per CPU
*/
struct Pager_thread: public Thread
{
Pager_thread(Affinity::Location location)
: Thread(Cpu_session::Weight::DEFAULT_WEIGHT, "pager", 2 * 4096, location)
{
/* creates local EC */
Thread::start();
reinterpret_cast<Nova::Utcb *>(Thread::utcb())->crd_xlt = Obj_crd(0, ~0UL);
}
void entry() override { }
};
enum { PAGER_CPUS = Core::Platform::MAX_SUPPORTED_CPUS };
static Constructible<Pager_thread> pager_threads[PAGER_CPUS];
static Pager_thread &pager_thread(Affinity::Location location,
Core::Platform &platform)
{
unsigned const pager_index = platform.pager_index(location);
unsigned const kernel_cpu_id = platform.kernel_cpu_id(location);
if (kernel_hip().is_cpu_enabled(kernel_cpu_id) &&
pager_index < PAGER_CPUS && pager_threads[pager_index].constructed())
return *pager_threads[pager_index];
warning("invalid CPU parameter used in pager object: ",
pager_index, "->", kernel_cpu_id, " location=",
location.xpos(), "x", location.ypos(), " ",
location.width(), "x", location.height());
throw Invalid_thread();
}
/**
* Utility for the formatted output of page-fault information
*/
struct Page_fault_info
{
char const * const pd;
char const * const thread;
unsigned const cpu;
addr_t const ip, addr, sp;
uint8_t const pf_type;
Page_fault_info(char const *pd, char const *thread, unsigned cpu,
addr_t ip, addr_t addr, addr_t sp, unsigned type)
:
pd(pd), thread(thread), cpu(cpu), ip(ip), addr(addr),
sp(sp), pf_type((uint8_t)type)
{ }
void print(Genode::Output &out) const
{
Genode::print(out, "pd='", pd, "' "
"thread='", thread, "' "
"cpu=", cpu, " "
"ip=", Hex(ip), " "
"address=", Hex(addr), " "
"stack pointer=", Hex(sp), " "
"qualifiers=", Hex(pf_type), " ",
pf_type & Ipc_pager::ERR_I ? "I" : "i",
pf_type & Ipc_pager::ERR_R ? "R" : "r",
pf_type & Ipc_pager::ERR_U ? "U" : "u",
pf_type & Ipc_pager::ERR_W ? "W" : "w",
pf_type & Ipc_pager::ERR_P ? "P" : "p");
}
};
void Pager_object::_page_fault_handler(Pager_object &obj)
{
Thread &myself = *Thread::myself();
Utcb &utcb = *reinterpret_cast<Utcb *>(myself.utcb());
Ipc_pager ipc_pager(utcb, obj.pd_sel(), platform_specific().core_pd_sel());
/* potential request to ask for EC cap or signal SM cap */
if (utcb.msg_words() == 1)
_invoke_handler(obj);
/*
* obj.pager() (pager thread) may issue a signal to the remote region
* handler thread which may respond via wake_up() (ep thread) before
* we are done here - we have to lock the whole page lookup procedure
*/
obj._state_lock.acquire();
obj._state.thread.ip = ipc_pager.fault_ip();
obj._state.thread.sp = 0;
obj._state.thread.trapno = PT_SEL_PAGE_FAULT;
obj._state.block();
obj._state.block_pause_sm();
/* lookup fault address and decide what to do */
unsigned error = (obj.pager(ipc_pager) == Pager_object::Pager_result::STOP);
/* don't open receive window for pager threads */
if (utcb.crd_rcv.value())
nova_die();
if (!error && ipc_pager.syscall_result() != Nova::NOVA_OK) {
/* something went wrong - by default don't answer the page fault */
error = 4;
/* dst pd has not enough kernel quota ? - try to recover */
if (ipc_pager.syscall_result() == Nova::NOVA_PD_OOM) {
uint8_t res = obj.handle_oom();
if (res == Nova::NOVA_PD_OOM) {
obj._state.unblock_pause_sm();
obj._state.unblock();
obj._state_lock.release();
/* block until revoke is due */
ipc_pager.reply_and_wait_for_fault(obj.sel_sm_block_oom());
} else if (res == Nova::NOVA_OK)
/* succeeded to recover - continue normally */
error = 0;
}
}
/* good case - found a valid region which is mappable */
if (!error) {
obj._state.unblock_pause_sm();
obj._state.unblock();
obj._state_lock.release();
ipc_pager.reply_and_wait_for_fault();
}
char const * const client_thread = obj.client_thread();
char const * const client_pd = obj.client_pd();
unsigned const cpu_id = platform_specific().pager_index(myself.affinity());
Page_fault_info const fault_info(client_pd, client_thread, cpu_id,
ipc_pager.fault_ip(),
ipc_pager.fault_addr(),
ipc_pager.sp(),
(uint8_t)ipc_pager.fault_type());
obj._state_lock.release();
/* block the faulting thread until region manager is done */
ipc_pager.reply_and_wait_for_fault(obj.sel_sm_block_pause());
}
void Pager_object::exception(uint8_t exit_id)
{
Thread &myself = *Thread::myself();
Utcb &utcb = *reinterpret_cast<Utcb *>(myself.utcb());
if (exit_id > PT_SEL_PARENT)
nova_die();
addr_t const fault_ip = utcb.ip;
addr_t const fault_sp = utcb.sp;
addr_t const fault_bp = utcb.bp;
uint8_t res = 0xFF;
addr_t mtd = 0;
_state_lock.acquire();
/* remember exception type for Cpu_session::state() calls */
_state.thread.trapno = exit_id;
if (_exception_sigh.valid()) {
_state.submit_signal();
res = _unsynchronized_client_recall(true);
}
if (res != NOVA_OK) {
/* nobody handles this exception - so thread will be stopped finally */
_state.mark_dead();
unsigned const cpu_id = platform_specific().pager_index(myself.affinity());
warning("unresolvable exception ", exit_id, ", "
"pd '", client_pd(), "', "
"thread '", client_thread(), "', "
"cpu ", cpu_id, ", "
"ip=", Hex(fault_ip), " "
"sp=", Hex(fault_sp), " "
"bp=", Hex(fault_bp), " ",
res == 0xFF ? "no signal handler"
: (res == NOVA_OK ? "" : "recall failed"));
Nova::revoke(Obj_crd(exc_pt_sel_client(), NUM_INITIAL_PT_LOG2));
enum { TRAP_BREAKPOINT = 3 };
if (exit_id == TRAP_BREAKPOINT) {
utcb.ip = fault_ip - 1;
mtd = Mtd::EIP;
}
}
_state_lock.release();
utcb.set_msg_word(0);
utcb.mtd = mtd;
reply(myself.stack_top());
}
bool Pager_object::_migrate_thread()
{
bool const valid_migrate = (_state.migrate() && _badge);
if (!valid_migrate)
return false;
_state.reset_migrate();
try {
/* revoke all exception portals pointing to current pager */
Platform_thread &thread = *reinterpret_cast<Platform_thread *>(_badge);
Nova::revoke(Obj_crd(_selectors, 2));
/* revoke all exception portals selectors */
Nova::revoke(Obj_crd(exc_pt_sel_client()+0x00, 4));
Nova::revoke(Obj_crd(exc_pt_sel_client()+0x10, 3));
Nova::revoke(Obj_crd(exc_pt_sel_client()+0x18, 1));
Nova::revoke(Obj_crd(exc_pt_sel_client()+0x1f, 0));
/* re-create portals bound to pager on new target CPU */
_location = _next_location;
_exceptions = Exception_handlers(*this);
_construct_pager();
/* map all exception portals to thread pd */
thread.prepare_migration();
/* syscall to migrate */
unsigned const migrate_to = platform_specific().kernel_cpu_id(_location);
uint8_t res = syscall_retry(*this, [&]() {
return ec_ctrl(EC_MIGRATE, _state.sel_client_ec, migrate_to,
Obj_crd(EC_SEL_THREAD, 0, Obj_crd::RIGHT_EC_RECALL));
});
if (res == Nova::NOVA_OK)
thread.finalize_migration(_location);
return true;
} catch (...) {
return false;
}
}
void Pager_object::_recall_handler(Pager_object &obj)
{
Thread &myself = *Thread::myself();
Utcb &utcb = *reinterpret_cast<Utcb *>(myself.utcb());
/* acquire mutex */
obj._state_lock.acquire();
/* check for migration */
if (obj._migrate_thread()) {
/* release mutex */
obj._state_lock.release();
utcb.set_msg_word(0);
utcb.mtd = 0;
reply(myself.stack_top());
}
if (obj._state.modified) {
obj._copy_state_to_utcb(utcb);
obj._state.modified = false;
} else
utcb.mtd = 0;
/* switch on/off single step */
bool singlestep_state = obj._state.thread.eflags & 0x100UL;
if (obj._state.singlestep() && !singlestep_state) {
utcb.flags |= 0x100UL;
utcb.mtd |= Mtd::EFL;
} else if (!obj._state.singlestep() && singlestep_state) {
utcb.flags &= ~0x100UL;
utcb.mtd |= Mtd::EFL;
}
/* deliver signal if it was requested */
if (obj._state.to_submit())
obj.submit_exception_signal();
/* block until Cpu_session()::resume() respectively wake_up() call */
unsigned long sm = 0;
if (obj._state.blocked()) {
sm = obj.sel_sm_block_pause();
obj._state.block_pause_sm();
}
obj._state_lock.release();
utcb.set_msg_word(0);
reply(myself.stack_top(), sm);
}
void Pager_object::_startup_handler(Pager_object &obj)
{
Thread &myself = *Thread::myself();
Utcb &utcb = *reinterpret_cast<Utcb *>(myself.utcb());
utcb.ip = obj._initial_eip;
utcb.sp = obj._initial_esp;
utcb.mtd = Mtd::EIP | Mtd::ESP;
if (obj._state.singlestep()) {
utcb.flags = 0x100UL;
utcb.mtd |= Mtd::EFL;
}
obj._state.unblock();
utcb.set_msg_word(0);
reply(myself.stack_top());
}
void Pager_object::_invoke_handler(Pager_object &obj)
{
Thread &myself = *Thread::myself();
Utcb &utcb = *reinterpret_cast<Utcb *>(myself.utcb());
/* receive window must be closed - otherwise implementation bug */
if (utcb.crd_rcv.value())
nova_die();
/* if protocol is violated ignore request */
if (utcb.msg_words() != 1) {
utcb.mtd = 0;
utcb.set_msg_word(0);
reply(myself.stack_top());
}
addr_t const event = utcb.msg()[0];
/* check for translated pager portals - required for vCPU in remote PDs */
if (utcb.msg_items() == 1 && utcb.msg_words() == 1 && event == 0xaffe) {
Nova::Utcb::Item const &item = *utcb.get_item(0);
Nova::Crd const cap(item.crd);
/* valid item which got translated ? */
if (!cap.is_null() && !item.is_del()) {
Rpc_entrypoint &e = core_env().entrypoint();
e.apply(cap.base(),
[&] (Cpu_thread_component *source) {
if (!source)
return;
Platform_thread &p = source->platform_thread();
addr_t const sel_exc_base = p.remote_vcpu();
if (sel_exc_base == Native_thread::INVALID_INDEX)
return;
/* delegate VM-exit portals */
map_vcpu_portals(p.pager(), sel_exc_base, sel_exc_base,
utcb, obj.pd_sel());
/* delegate portal to contact pager */
map_pagefault_portal(obj, p.pager().exc_pt_sel_client(),
sel_exc_base, obj.pd_sel(), utcb);
});
}
utcb.mtd = 0;
utcb.set_msg_word(0);
reply(myself.stack_top());
}
utcb.mtd = 0;
utcb.set_msg_word(0);
/* native ec cap requested */
if (event == ~0UL) {
/**
* Return native EC cap with specific rights mask set.
* If the cap is mapped the kernel will demote the
* rights of the EC as specified by the rights mask.
*
* The cap is supposed to be returned to clients,
* which they have to use as argument to identify
* the thread to which they want attach portals.
*
* The demotion by the kernel during the map operation
* takes care that the EC cap itself contains
* no usable rights for the clients.
*/
bool res = utcb.append_item(Obj_crd(obj._state.sel_client_ec, 0,
Obj_crd::RIGHT_EC_RECALL), 0);
(void)res;
}
/* semaphore for signaling thread is requested, reuse PT_SEL_STARTUP. */
if (event == ~0UL - 1) {
/* create semaphore only once */
if (!obj._state.has_signal_sm()) {
revoke(Obj_crd(obj.exc_pt_sel_client() + PT_SEL_STARTUP, 0));
bool res = Nova::create_sm(obj.exc_pt_sel_client() + PT_SEL_STARTUP,
platform_specific().core_pd_sel(), 0);
if (res != Nova::NOVA_OK)
reply(myself.stack_top());
obj._state.mark_signal_sm();
}
bool res = utcb.append_item(Obj_crd(obj.exc_pt_sel_client() +
PT_SEL_STARTUP, 0), 0);
(void)res;
}
reply(myself.stack_top());
}
void Pager_object::wake_up()
{
Mutex::Guard _state_lock_guard(_state_lock);
if (!_state.blocked())
return;
_state.thread.exception = false;
_state.unblock();
if (_state.blocked_pause_sm()) {
uint8_t res = sm_ctrl(sel_sm_block_pause(), SEMAPHORE_UP);
if (res == NOVA_OK)
_state.unblock_pause_sm();
else
warning("canceling blocked client failed (thread sm)");
}
}
uint8_t Pager_object::client_recall(bool get_state_and_block)
{
Mutex::Guard _state_lock_guard(_state_lock);
return _unsynchronized_client_recall(get_state_and_block);
}
uint8_t Pager_object::_unsynchronized_client_recall(bool get_state_and_block)
{
enum { STATE_REQUESTED = 1UL, STATE_INVALID = ~0UL };
uint8_t res = ec_ctrl(EC_RECALL, _state.sel_client_ec,
get_state_and_block ? STATE_REQUESTED : STATE_INVALID);
if (res != NOVA_OK)
return res;
if (get_state_and_block) {
Utcb &utcb = *reinterpret_cast<Utcb *>(Thread::myself()->utcb());
_copy_state_from_utcb(utcb);
_state.block();
}
return res;
}
void Pager_object::cleanup_call()
{
_state.mark_dissolved();
/* revoke ec and sc cap of client before the sm cap */
if (_state.sel_client_ec != Native_thread::INVALID_INDEX)
revoke(Obj_crd(_state.sel_client_ec, 2));
/* revoke all portals handling the client. */
revoke(Obj_crd(exc_pt_sel_client(), NUM_INITIAL_PT_LOG2));
Utcb &utcb = *reinterpret_cast<Utcb *>(Thread::myself()->utcb());
utcb.set_msg_word(0);
utcb.mtd = 0;
if (uint8_t res = call(sel_pt_cleanup()))
error(&utcb, " - cleanup call to pager failed res=", res);
}
void Pager_object::print(Output &out) const
{
Platform_thread const * const faulter = reinterpret_cast<Platform_thread *>(_badge);
Genode::print(out, "pager_object: pd='",
faulter ? faulter->pd_name() : "unknown", "' thread='",
faulter ? faulter->name() : "unknown", "'");
}
static uint8_t create_portal(addr_t pt, addr_t pd, addr_t ec, Mtd mtd,
addr_t eip, Pager_object * oom_handler)
{
uint8_t res = syscall_retry(*oom_handler,
[&]() { return create_pt(pt, pd, ec, mtd, eip); });
if (res != NOVA_OK)
return res;
addr_t const badge_localname = reinterpret_cast<addr_t>(oom_handler);
res = pt_ctrl(pt, badge_localname);
if (res == NOVA_OK)
revoke(Obj_crd(pt, 0, Obj_crd::RIGHT_PT_CTRL));
else
revoke(Obj_crd(pt, 0));
return res;
}
/************************
** Exception handlers **
************************/
template <uint8_t EV>
void Exception_handlers::register_handler(Pager_object &obj, Mtd mtd,
void (* __attribute__((regparm(1))) func)(Pager_object &))
{
addr_t const ec_sel = pager_thread(obj.location(), platform_specific()).native_thread().ec_sel;
/* compiler generates instance of exception entry if not specified */
addr_t entry = func ? (addr_t)func : (addr_t)(&_handler<EV>);
uint8_t res = create_portal(obj.exc_pt_sel_client() + EV,
platform_specific().core_pd_sel(), ec_sel, mtd, entry, &obj);
if (res != Nova::NOVA_OK)
throw Invalid_thread();
}
template <uint8_t EV>
void Exception_handlers::_handler(Pager_object &obj)
{
obj.exception(EV);
}
Exception_handlers::Exception_handlers(Pager_object &obj)
{
Mtd const mtd (Mtd::EBSD | Mtd::ESP | Mtd::EIP);
register_handler<0>(obj, mtd);
register_handler<1>(obj, mtd);
register_handler<2>(obj, mtd);
register_handler<3>(obj, mtd);
register_handler<4>(obj, mtd);
register_handler<5>(obj, mtd);
register_handler<6>(obj, mtd);
register_handler<7>(obj, mtd);
register_handler<8>(obj, mtd);
register_handler<9>(obj, mtd);
register_handler<10>(obj, mtd);
register_handler<11>(obj, mtd);
register_handler<12>(obj, mtd);
register_handler<13>(obj, mtd);
register_handler<15>(obj, mtd);
register_handler<16>(obj, mtd);
register_handler<17>(obj, mtd);
register_handler<18>(obj, mtd);
register_handler<19>(obj, mtd);
register_handler<20>(obj, mtd);
register_handler<21>(obj, mtd);
register_handler<22>(obj, mtd);
register_handler<23>(obj, mtd);
register_handler<24>(obj, mtd);
register_handler<25>(obj, mtd);
}
/******************
** Pager object **
******************/
void Pager_object::_construct_pager()
{
addr_t const pd_sel = platform_specific().core_pd_sel();
addr_t const ec_sel = pager_thread(_location, platform_specific()).native_thread().ec_sel;
/* create portal for page-fault handler - 14 */
_exceptions.register_handler<14>(*this, Mtd::QUAL | Mtd::ESP | Mtd::EIP,
_page_fault_handler);
/* create portal for recall handler */
Mtd const mtd_recall(Mtd::ESP | Mtd::EIP | Mtd::ACDB | Mtd::EFL |
Mtd::EBSD | Mtd::FSGS);
_exceptions.register_handler<PT_SEL_RECALL>(*this, mtd_recall,
_recall_handler);
/* create portal for final cleanup call used during destruction */
uint8_t res = create_portal(sel_pt_cleanup(), pd_sel, ec_sel, Mtd(0),
reinterpret_cast<addr_t>(_invoke_handler),
this);
if (res != Nova::NOVA_OK) {
error("could not create pager cleanup portal, error=", res);
throw Invalid_thread();
}
/* semaphore used to block paged thread during recall */
res = Nova::create_sm(sel_sm_block_pause(), pd_sel, 0);
if (res != Nova::NOVA_OK) {
throw Invalid_thread();
}
/* semaphore used to block paged thread during OOM memory revoke */
res = Nova::create_sm(sel_sm_block_oom(), pd_sel, 0);
if (res != Nova::NOVA_OK) {
throw Invalid_thread();
}
}
Pager_object::Pager_object(Cpu_session_capability cpu_session_cap,
Thread_capability thread_cap, unsigned long badge,
Affinity::Location location, Session_label const &,
Cpu_session::Name const &)
:
_badge(badge),
_selectors(cap_map().insert(2)),
_client_exc_pt_sel(cap_map().insert(NUM_INITIAL_PT_LOG2)),
_cpu_session_cap(cpu_session_cap), _thread_cap(thread_cap),
_location(location),
_exceptions(*this),
_pd_target(Native_thread::INVALID_INDEX)
{
_state._status = 0;
_state.modified = false;
_state.sel_client_ec = Native_thread::INVALID_INDEX;
_state.block();
if (Native_thread::INVALID_INDEX == _selectors ||
Native_thread::INVALID_INDEX == _client_exc_pt_sel)
throw Invalid_thread();
_construct_pager();
/* create portal for startup handler */
Mtd const mtd_startup(Mtd::ESP | Mtd::EIP);
_exceptions.register_handler<PT_SEL_STARTUP>(*this, mtd_startup,
_startup_handler);
/*
* Create semaphore required for Genode locking. It can be later on
* requested by the thread the same way as all exception portals.
*/
addr_t const pd_sel = platform_specific().core_pd_sel();
uint8_t const res = Nova::create_sm(exc_pt_sel_client() + SM_SEL_EC,
pd_sel, 0);
if (res != Nova::NOVA_OK)
throw Invalid_thread();
}
void Pager_object::migrate(Affinity::Location location)
{
Mutex::Guard _state_lock_guard(_state_lock);
if (_state.blocked())
return;
if (location.xpos() == _location.xpos() &&
location.ypos() == _location.ypos())
return;
/* initiate migration by recall handler */
bool const just_recall = false;
uint8_t const res = _unsynchronized_client_recall(just_recall);
if (res == Nova::NOVA_OK) {
_next_location = location;
_state.request_migrate();
}
}
Pager_object::~Pager_object()
{
/* sanity check that object got dissolved already - otherwise bug */
if (!_state.dissolved())
nova_die();
/* revoke portal used for the cleanup call and sm cap for blocking state */
revoke(Obj_crd(_selectors, 2));
cap_map().remove(_selectors, 2, false);
cap_map().remove(exc_pt_sel_client(), NUM_INITIAL_PT_LOG2, false);
}
uint8_t Pager_object::handle_oom(addr_t transfer_from,
char const * src_pd, char const * src_thread,
enum Pager_object::Policy policy)
{
return handle_oom(transfer_from, pd_sel(), src_pd, src_thread, policy,
sel_sm_block_oom(), client_pd(), client_thread());
}
uint8_t Pager_object::handle_oom(addr_t pd_from, addr_t pd_to,
char const * src_pd, char const * src_thread,
Policy policy, addr_t sm_notify,
char const * dst_pd, char const * dst_thread)
{
addr_t const core_pd_sel = platform_specific().core_pd_sel();
enum { QUOTA_TRANSFER_PAGES = 2 };
if (pd_from == SRC_CORE_PD)
pd_from = core_pd_sel;
/* request current kernel quota usage of target pd */
addr_t limit_before = 0, usage_before = 0;
Nova::pd_ctrl_debug(pd_to, limit_before, usage_before);
if (verbose_oom) {
addr_t limit_source = 0, usage_source = 0;
/* request current kernel quota usage of source pd */
Nova::pd_ctrl_debug(pd_from, limit_source, usage_source);
log("oom - '", dst_pd, "':'", dst_thread, "' "
"(", usage_before, "/", limit_before, ") - "
"transfer ", (long)QUOTA_TRANSFER_PAGES, " pages "
"from '", src_pd, "':'", src_thread, "' "
"(", usage_source, "/", limit_source, ")");
}
uint8_t res = Nova::NOVA_PD_OOM;
if (pd_from != pd_to) {
/* upgrade quota */
uint8_t res = Nova::pd_ctrl(pd_from, Pd_op::TRANSFER_QUOTA,
pd_to, QUOTA_TRANSFER_PAGES);
if (res == Nova::NOVA_OK)
return res;
}
/* retry upgrade using core quota if policy permits */
if (policy == UPGRADE_PREFER_SRC_TO_DST) {
if (pd_from != core_pd_sel) {
res = Nova::pd_ctrl(core_pd_sel, Pd_op::TRANSFER_QUOTA,
pd_to, QUOTA_TRANSFER_PAGES);
if (res == Nova::NOVA_OK)
return res;
}
}
warning("kernel memory quota upgrade failed - trigger memory free up for "
"causing '", dst_pd, "':'", dst_thread, "' - "
"donator is '", src_pd, "':'", src_thread, "', "
"policy=", (int)policy);
/* if nothing helps try to revoke memory */
enum { REMOTE_REVOKE = true, PD_SELF = true };
Mem_crd crd_all(0, ~0U, Rights(true, true, true));
Nova::revoke(crd_all, PD_SELF, REMOTE_REVOKE, pd_to, sm_notify);
/* re-request current kernel quota usage of target pd */
addr_t limit_after = 0, usage_after = 0;
Nova::pd_ctrl_debug(pd_to, limit_after, usage_after);
/* if we could free up memory we continue */
if (usage_after < usage_before)
return Nova::NOVA_OK;
/*
* There is still the chance that memory gets freed up, but one has to
* wait until RCU period is over. If we are in the pager code, we can
* instruct the kernel to block the faulting client thread during the reply
* syscall. If we are in a normal (non-pagefault) RPC service call,
* we can't block. The caller of this function can decide based on
* the return value what to do and whether blocking is ok.
*/
return Nova::NOVA_PD_OOM;
}
void Pager_object::_oom_handler(addr_t pager_dst, addr_t pager_src,
addr_t reason)
{
if (sizeof(void *) == 4) {
/* On 32 bit edx and ecx as second and third regparm parameter is not
* available. It is used by the kernel internally to store ip/sp.
*/
asm volatile ("" : "=D" (pager_src));
asm volatile ("" : "=S" (reason));
}
Thread &myself = *Thread::myself();
Utcb &utcb = *reinterpret_cast<Utcb *>(myself.utcb());
Pager_object &obj_dst = *reinterpret_cast<Pager_object *>(pager_dst);
Pager_object &obj_src = *reinterpret_cast<Pager_object *>(pager_src);
/* Policy used if the Process of the paged thread runs out of memory */
enum Policy policy = Policy::UPGRADE_CORE_TO_DST;
/* check assertions - cases that should not happen on Genode@Nova */
enum { NO_OOM_PT = 0UL };
/* all relevant (user) threads should have a OOM PT */
bool assert = pager_dst == NO_OOM_PT;
/*
* This pager thread does solely reply to IPC calls - it should never
* cause OOM during the sending phase of a IPC.
*/
assert |= ((reason & (SELF | SEND)) == (SELF | SEND));
/*
* This pager thread should never send words (untyped items) - it just
* answers page faults by typed items (memory mappings).
*/
assert |= utcb.msg_words();
if (assert) {
error("unknown OOM case - stop core pager thread");
utcb.set_msg_word(0);
reply(myself.stack_top(), myself.native_thread().exc_pt_sel + Nova::SM_SEL_EC);
}
/* be strict in case of the -strict- STOP policy - stop causing thread */
if (policy == STOP) {
error("PD has insufficient kernel memory left - stop thread");
utcb.set_msg_word(0);
reply(myself.stack_top(), obj_dst.sel_sm_block_pause());
}
char const * src_pd = "core";
char const * src_thread = "pager";
addr_t transfer_from = SRC_CORE_PD;
switch (pager_src) {
case SRC_PD_UNKNOWN:
/* should not happen on Genode - we create and know every PD in core */
error("Unknown PD has insufficient kernel memory left - stop thread");
utcb.set_msg_word(0);
reply(myself.stack_top(), myself.native_thread().exc_pt_sel + Nova::SM_SEL_EC);
case SRC_CORE_PD:
/* core PD -> other PD, which has insufficient kernel resources */
if (!(reason & SELF)) {
/* case that src thread != this thread in core */
src_thread = "unknown";
utcb.set_msg_word(0);
}
transfer_from = platform_specific().core_pd_sel();
break;
default:
/* non core PD -> non core PD */
utcb.set_msg_word(0);
if (pager_src == pager_dst || policy == UPGRADE_CORE_TO_DST)
transfer_from = platform_specific().core_pd_sel();
else {
/* delegation of items between different PDs */
src_pd = obj_src.client_pd();
src_thread = obj_src.client_thread();
transfer_from = obj_src.pd_sel();
}
}
uint8_t res = obj_dst.handle_oom(transfer_from, src_pd, src_thread, policy);
if (res == Nova::NOVA_OK)
/* handling succeeded - continue with original IPC */
reply(myself.stack_top());
/* transfer nothing */
utcb.set_msg_word(0);
if (res != Nova::NOVA_PD_OOM)
error("upgrading kernel memory failed, policy ", (int)policy, ", "
"error ", (int)res, " - stop thread finally");
/* else: caller will get blocked until RCU period is over */
/* block caller in semaphore */
reply(myself.stack_top(), obj_dst.sel_sm_block_oom());
}
addr_t Pager_object::create_oom_portal()
{
try {
addr_t const pt_oom = sel_oom_portal();
addr_t const core_pd_sel = platform_specific().core_pd_sel();
Pager_thread &thread = pager_thread(_location, platform_specific());
addr_t const ec_sel = thread.native_thread().ec_sel;
uint8_t res = create_portal(pt_oom, core_pd_sel, ec_sel, Mtd(0),
reinterpret_cast<addr_t>(_oom_handler),
this);
if (res == Nova::NOVA_OK)
return pt_oom;
} catch (...) { }
error("creating portal for out of memory notification failed");
return 0;
}
const char * Pager_object::client_thread() const
{
Platform_thread * client = reinterpret_cast<Platform_thread *>(_badge);
return client ? client->name() : "unknown";
}
const char * Pager_object::client_pd() const
{
Platform_thread * client = reinterpret_cast<Platform_thread *>(_badge);
return client ? client->pd_name() : "unknown";
}
/**********************
** Pager entrypoint **
**********************/
Pager_entrypoint::Pager_entrypoint(Rpc_cap_factory &)
{
/* sanity check for pager threads */
if (kernel_hip().cpu_max() > PAGER_CPUS) {
error("kernel supports more CPUs (", kernel_hip().cpu_max(), ") "
"than Genode (", (unsigned)PAGER_CPUS, ")");
nova_die();
}
/* detect enabled CPUs and create per CPU a pager thread */
platform_specific().for_each_location([&](Affinity::Location &location) {
unsigned const pager_index = platform_specific().pager_index(location);
unsigned const kernel_cpu_id = platform_specific().kernel_cpu_id(location);
if (!kernel_hip().is_cpu_enabled(kernel_cpu_id))
return;
pager_threads[pager_index].construct(location);
});
}
void Pager_entrypoint::dissolve(Pager_object &obj)
{
/* take care that no faults are in-flight */
obj.cleanup_call();
}
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