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

   1 /*
   2  * romain_pagefault.cc --
   3  *
   4  *     Implementation of page fault handling.
   5  *
   6  * (c) 2011 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 #define MSG() DEBUGf(Romain::Log::Memory) << "[" << i->id() << "] "
  33
  34 /*****************************************************************
  35  *                  Page Fault Handling                          *
  36  *****************************************************************/
  37 DEFINE_EMPTY_STARTUP(PageFaultObserver)
  38
  39 void Romain::PageFaultObserver::status() const
  40 {
  41         INFO() << "Page faults so far: mapped " << pf_mapped << " write emu "
  42                << pf_write << " kip " << pf_kip;
  43 }
  44
  45 Romain::Observer::ObserverReturnVal
  46 Romain::PageFaultObserver::notify(Romain::App_instance *i, Romain::App_thread *t, Romain::App_model *a)
  47 {
  48         if (!t->vcpu()->is_page_fault_entry())
  49                 return Romain::Observer::Ignored;
  50
  51         if (t->unhandled_pf()) {
  52                 enter_kdebug("unhandled pf");
  53         }
  54
  55         L4vcpu::Vcpu *vcpu = t->vcpu();
  56
  57         bool write_pf = vcpu->r()->err & 0x2;
  58         l4_addr_t pfa = vcpu->r()->pfa;
  59
  60         MSG() << (write_pf ? "\033[31mwrite\033[0m" : "\033[34;1mread\033[0m")
  61               << " page fault @ 0x" << std::hex << pfa;
  62
  63         Romain::Region_map::Base::Node n = a->rm()->find(pfa);
  64         MSG() << "rm_find(" << std::hex << pfa << ") = " << n;
  65         if (n) {
  66                 a->rm()->lazy_map_region(n, i->id());
  67
  68                 /*
  69                  * Lazily establish region handlers for replicas
  70                  */
  71                 MSG() << "[" << std::hex
  72                         << n->second.local_region(i->id()).start() << " - "
  73                         << n->second.local_region(i->id()).end() << "] ==> "
  74                         << "[" << n->first.start() << " - "
  75                         << n->first.end() << "]";
  76                 MSG() << "   DS " << std::hex <<  n->second.memory(i->id()).cap();
  77
  78                 if (write_pf && (always_readonly() ||
  79                                 (n->second.writable() == Romain::Region_handler::Read_only_emulate_write))) {
  80                         ++pf_write;
  81                         Romain::WriteEmulator(vcpu, Romain::AppModelAddressTranslator(a, i)).emulate();
  82                         // writes are emulated, no need to map here at all
  83                         // -> XXX actually, we could also map() here, because if the client
  84                         //        writes to memory, it's most probably going to read this
  85                         //        data at a later point in time, too
  86
  87                         /*
  88                          * For emulated operations single-stepping won't work, because
  89                          * the real instruction is never executed in the target AS. Therefore,
  90                          * we need to inject a "virtual" INT1 into the manager here.
  91                          */
  92                         if (t->vcpu()->r()->flags & TrapFlag)
  93                                 t->set_pending_trap(1);
  94                 } else {
  95                         ++pf_mapped;
  96
  97                         l4_addr_t offset_in_region = l4_trunc_page(pfa - n->first.start());
  98                         MSG() << "offs in region: " << std::hex << offset_in_region;
  99
 100                         // set flags properly, only check ro(), because else we'd already ended
 101                         // up in the emulation branch above
 102                         unsigned pageflags           = n->second.is_ro() ? L4_FPAGE_RO : L4_FPAGE_RW;
 103                         unsigned map_size            = L4_PAGESIZE;
 104                         unsigned size_left_in_region = n->first.end() - (n->first.start() + offset_in_region);
 105
 106 #if 0
 107 #define MAX_MAP_SHIFT 0
 108                         for (unsigned x = 1; x < MAX_MAP_SHIFT; ++x) {
 109                                 if (size_left_in_region >= (1 << (L4_PAGESHIFT + x)))
 110                                         map_size *= 2;
 111                         }
 112 #undef MAX_MAP_SHIFT
 113 #endif
 114
 115                         i->map(n->second.local_region(i->id()).start() + offset_in_region, // local addr
 116                                    n->first.start() + offset_in_region,                        // remote addr
 117                                    pageflags, map_size);
 118                 }
 119
 120         } else if ((a->prog_info()->kip <= pfa) && (pfa < a->prog_info()->kip + L4_PAGESIZE)) {
 121             ++pf_kip;
 122             MSG() << "KIP access ";
 123             /* XXX ??? */
 124                 MSG() << std::hex << __libc_l4_gettime << " " <<  *(l4_addr_t*)__libc_l4_gettime;
 125             t->set_unhandled_pf();
 126         } else {
 127                 ERROR() << "Unhandled page fault @ address 0x" << std::hex << pfa
 128                         << " PC @ 0x" << vcpu->r()->ip;
 129                 t->set_unhandled_pf();
 130         }
 131
 132         /*
 133          * XXX: For now, tell the manager to let all instances perform their fault handling
 134          *      independently. In fact, we could however also handle all faults upon first
 135          *      occurrence and return Replicatable here.
 136          */
 137         MSG() << "Page faults so far: mapped " << pf_mapped << " write emu " << pf_write << " kip " << pf_kip;
 138         return Romain::Observer::Finished;
 139 }
 140
 141
 142 Romain::PageFaultObserver::PageFaultObserver()
 143 {
 144         char const *ro = ConfigStringValue("general:page_fault_handling");
 145
 146         if (ro && (strcmp(ro, "ro") == 0)) {
 147                 _readonly = true;
 148         } else {
 149                 _readonly = false;
 150         }
 151 }