System calls support

src/boot/bootstrap.s

@@ -223,6 +223,7 @@ x64_entry:
   call _ZN10Interrupts4initEv
   call _ZN3SMP4initEv
   call _ZN13ModuleManager4initEv
+  call _ZN7Syscall5setupEv
   mov %rsp, %rbp
   jmp _ZN14ProcessManager12process_loopEv
 

src/platform/include/syscall.hpp

@@ -0,0 +1,25 @@
+//    PhoeniX OS System calls subsystem
+//    Copyright (C) 2013  PhoeniX
+//
+//    This program is free software: you can redistribute it and/or modify
+//    it under the terms of the GNU General Public License as published by
+//    the Free Software Foundation, either version 3 of the License, or
+//    (at your option) any later version.
+//
+//    This program is distributed in the hope that it will be useful,
+//    but WITHOUT ANY WARRANTY; without even the implied warranty of
+//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//    GNU General Public License for more details.
+//
+//    You should have received a copy of the GNU General Public License
+//    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#pragma once
+#include "kernlib.hpp"
+
+class Syscall {
+ public:
+  static void setup();
+ private:
+  static void wrapper();
+};

src/platform/smp.cpp

@@ -17,6 +17,7 @@
 #include "kernlib.hpp"
 #include "acpi.hpp"
 #include "processmanager.hpp"
+#include "syscall.hpp"
 
 class SMP {
  private:
@@ -31,6 +32,7 @@ Mutex SMP::startupMutex;
 void SMP::setup() {
   Interrupts::loadVector();
   ACPI::getController()->activateCPU();
+  Syscall::setup();
   startupMutex.lock();
   startupMutex.release();
 }

src/platform/syscall.cpp

@@ -0,0 +1,48 @@
+//    PhoeniX OS System calls subsystem
+//    Copyright (C) 2013  PhoeniX
+//
+//    This program is free software: you can redistribute it and/or modify
+//    it under the terms of the GNU General Public License as published by
+//    the Free Software Foundation, either version 3 of the License, or
+//    (at your option) any later version.
+//
+//    This program is distributed in the hope that it will be useful,
+//    but WITHOUT ANY WARRANTY; without even the implied warranty of
+//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//    GNU General Public License for more details.
+//
+//    You should have received a copy of the GNU General Public License
+//    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#include "syscall.hpp"
+
+static const uint32_t MSR_EFER = 0xC0000080;
+static const uint32_t MSR_STAR = 0xC0000081;
+static const uint32_t MSR_LSTAR = 0xC0000082;
+static const uint64_t MSR_EFER_SCE = 1 << 0;
+static const uint16_t KERNEL_CS = 8;
+static const uint16_t USER_CS = 24;
+
+static inline void wrmsr(uint32_t msr_id, uint64_t msr_value) {
+  asm volatile("wrmsr"::"c"(msr_id), "A"(msr_value), "d"(msr_value >> 32));
+}
+
+static inline uint64_t rdmsr(uint32_t msr_id) {
+  uint64_t msr_hi, msr_lo;
+  asm volatile("rdmsr":"=A"(msr_lo), "=d"(msr_hi):"c"(msr_id));
+  return (msr_hi << 32) | msr_lo;
+}
+
+void __attribute((naked)) Syscall::wrapper() {
+  asm volatile(
+      "sysretq;"
+  );
+}
+
+void Syscall::setup() {
+  wrmsr(MSR_STAR,
+      ((uint64_t)USER_CS) << 48 |
+      ((uint64_t)KERNEL_CS) << 32);
+  wrmsr(MSR_LSTAR, (uintptr_t)wrapper);
+  wrmsr(MSR_EFER, rdmsr(MSR_EFER) | MSR_EFER_SCE);
+}

src/process/process.cpp

@@ -150,7 +150,10 @@ uintptr_t Process::linkLibrary(const char* funcname) {
   ptr = addSection(SectionTypeCode, 0x100);
 
   // TODO: actual link
-  uint8_t _stub[] = {0xc3};  // RET
+  uint8_t _stub[] = {
+    0x0f, 0x05,  // SYSCALL
+    0xc3         // RET
+  };
   writeData(ptr, _stub, sizeof(_stub));
   addSymbol(funcname, ptr);
 
@@ -240,10 +243,13 @@ void Process::startup() {
       addPage(page, reinterpret_cast<void*>(page), 5);
     }
   }
-  uintptr_t handler;
+  uintptr_t handler, sc_wrapper;
   asm volatile("lea __interrupt_wrap(%%rip), %q0":"=r"(handler));
+  asm volatile("lea _ZN7Syscall7wrapperEv(%%rip), %q0":"=r"(sc_wrapper));
   handler &= KB4;
+  sc_wrapper &= KB4;
   addPage(handler, reinterpret_cast<void*>(handler), 5);
+  addPage(sc_wrapper, reinterpret_cast<void*>(sc_wrapper), 5);
   GDT_ENT *gdt_ent = reinterpret_cast<GDT_ENT*>(
       (uintptr_t)gdt.addr + 8 * 3);
   GDT_ENT *gdt_top = reinterpret_cast<GDT_ENT*>(