l4/pkg/plr/server/src/fault_handlers/pagefault.cc

   1 /*
   2  * pagefault.cc --
   3  *
   4  *     Implementation of page fault handling.
   5  *
   6  * (c) 2011-2012 Björn Döbel <doebel@os.inf.tu-dresden.de>,
   7  *     economic rights: Technische Universität Dresden (Germany)
   8  * This file is part of TUD:OS and distributed under the terms of the
   9  * GNU General Public License 2.
  10  * Please see the COPYING-GPL-2 file for details.
  11  */
  12
  13 #include "../constants.h"
  14 #include "../log"
  15 #include "../exceptions"
  16 #include "../memory"
  17 #include "../emulation"
  18 #include "../app_loading"
  19 #include "../locking.h"
  20 #include "../configuration"
  21
  22 #include "observers.h"
  23
  24 #include <l4/sys/kdebug.h>
  25 #include <l4/util/bitops.h>
  26
  27 extern l4_addr_t __libc_l4_gettime;
  28
  29 static int pf_write  = 0; // statistical counter
  30 static int pf_mapped = 0; // statistical counter
  31 static int pf_kip    = 0; // statistical counter
  32
  33 #define MSG() DEBUGf(Romain::Log::Memory) << "[" << i->id() << "] "
  34 #define MSGt(t) DEBUGf(Romain::Log::Faults) << "[" << t->vcpu() << "] "
  35
  36 /*****************************************************************
  37  *                  Page Fault Handling                          *
  38  *****************************************************************/
  39 DEFINE_EMPTY_STARTUP(PageFaultObserver)
  40
  41 void Romain::PageFaultObserver::status() const
  42 {
  43         INFO() << "Page faults so far: mapped " << pf_mapped << " write emu "
  44                << pf_write << " kip " << pf_kip;
  45 }
  46
  47 Romain::Observer::ObserverReturnVal
  48 Romain::PageFaultObserver::notify(Romain::App_instance *i, Romain::App_thread *t,
  49                                   Romain::Thread_group* tg, Romain::App_model *a)
  50 {
  51         if (!t->vcpu()->is_page_fault_entry())
  52                 return Romain::Observer::Ignored;
  53
  54         if (t->unhandled_pf()) {
  55                 enter_kdebug("unhandled pf");
  56         }
  57
  58         L4vcpu::Vcpu *vcpu = t->vcpu();
  59
  60         bool write_pf = vcpu->r()->err & 0x2;
  61         l4_addr_t pfa = vcpu->r()->pfa;
  62
  63         MSGt(t) << (write_pf ? "\033[31mwrite\033[0m" : "\033[34;1mread\033[0m")
  64               << " page fault @ 0x" << std::hex << pfa;
  65
  66         Romain::Region_map::Base::Node n = a->rm()->find(pfa);
  67         MSGt(t) << "rm_find(" << std::hex << pfa << ") = " << n;
  68         if (n) {
  69                 a->rm()->lazy_map_region(n, i->id());
  70
  71                 /*
  72                  * Lazily establish region handlers for replicas
  73                  */
  74                 MSGt(t) << "[" << std::hex
  75                         << n->second.local_region(i->id()).start() << " - "
  76                         << n->second.local_region(i->id()).end() << "] ==> "
  77                         << "[" << n->first.start() << " - "
  78                         << n->first.end() << "]";
  79                 MSGt(t) << "   DS " << std::hex <<  n->second.memory(i->id()).cap();
  80
  81                 if (write_pf && (always_readonly() ||
  82                                 (n->second.writable() == Romain::Region_handler::Read_only_emulate_write))) {
  83                         ++pf_write;
  84                         /* XXX: can we use a static object here instead? */
  85                         AppModelAddressTranslator *aat = new AppModelAddressTranslator(a, i);
  86                         Romain::WriteEmulator(vcpu, aat).emulate();
  87                         delete aat;
  88                         // writes are emulated, no need to map here at all
  89                         // -> XXX actually, we could also map() here, because if the client
  90                         //        writes to memory, it's most probably going to read this
  91                         //        data at a later point in time, too
  92
  93                         /*
  94                          * For emulated operations single-stepping won't work, because
  95                          * the real instruction is never executed in the target AS. Therefore,
  96                          * we need to inject a "virtual" INT1 into the manager here.
  97                          */
  98                         if (t->vcpu()->r()->flags & TrapFlag)
  99                                 t->set_pending_trap(1);
 100                 } else {
 101                         ++pf_mapped;
 102
 103                         l4_addr_t offset_in_region = l4_trunc_page(pfa - n->first.start());
 104                         MSGt(t) << "offs in region: " << std::hex << offset_in_region;
 105
 106                         // set flags properly, only check ro(), because else we'd already ended
 107                         // up in the emulation branch above
 108                         unsigned pageflags           = n->second.is_ro() ? L4_FPAGE_RO : L4_FPAGE_RW;
 109                         unsigned map_size            = L4_PAGESIZE;
 110                         unsigned size_left_in_region = n->first.end() - (n->first.start() + offset_in_region);
 111
 112 #if 0
 113 #define MAX_MAP_SHIFT 0
 114                         for (unsigned x = 1; x < MAX_MAP_SHIFT; ++x) {
 115                                 if (size_left_in_region >= (1 << (L4_PAGESHIFT + x)))
 116                                         map_size *= 2;
 117                         }
 118 #undef MAX_MAP_SHIFT
 119 #endif
 120
 121                         i->map(n->second.local_region(i->id()).start() + offset_in_region, // local addr
 122                                    n->first.start() + offset_in_region,                        // remote addr
 123                                    pageflags, map_size);
 124                 }
 125
 126         } else if ((a->prog_info()->kip <= pfa) && (pfa < a->prog_info()->kip + L4_PAGESIZE)) {
 127             ++pf_kip;
 128             MSGt(t) << "KIP access ";
 129             /* XXX ??? */
 130                 MSGt(t) << std::hex << __libc_l4_gettime << " " <<  *(l4_addr_t*)__libc_l4_gettime;
 131             t->set_unhandled_pf();
 132         } else {
 133                 ERROR() << "Unhandled page fault @ address 0x" << std::hex << pfa
 134                         << " PC @ 0x" << vcpu->r()->ip;
 135                 t->set_unhandled_pf();
 136         }
 137
 138         /*
 139          * XXX: For now, tell the manager to let all instances perform their fault handling
 140          *      independently. In fact, we could however also handle all faults upon first
 141          *      occurrence and return Replicatable here.
 142          */
 143         MSGt(t) << "Page faults so far: mapped " << pf_mapped << " write emu " << pf_write << " kip " << pf_kip;
 144
 145         return Romain::Observer::Finished;
 146 }
 147
 148
 149 Romain::PageFaultObserver::PageFaultObserver()
 150 {
 151         char const *ro = ConfigStringValue("general:page_fault_handling");
 152
 153         if (ro && (strcmp(ro, "ro") == 0)) {
 154                 _readonly = true;
 155         } else {
 156                 _readonly = false;
 157         }
 158 }