Kernel: Add exception_code to RegisterDump.

Added the exception_code field to RegisterDump, removing the need
for RegisterDumpWithExceptionCode. To accomplish this, I had to
push a dummy exception code during some interrupt entries to properly
pad out the RegisterDump. Note that we also needed to change some code
in sys$sigreturn to deal with the new RegisterDump layout.

Kernel/Arch/i386/CPU.cpp

@@ -46,6 +46,7 @@ extern "C" void asm_irq_entry();
 asm(
  ".globl asm_irq_entry\n"
  "asm_irq_entry: \n"
+ " pushl $0x0\n"
  " pusha\n"
  " pushw %ds\n"
  " pushw %es\n"
@@ -57,10 +58,11 @@ asm(
  " popw %es\n"
  " popw %ds\n"
  " popa\n"
+ " add $0x4, %esp\n"
  " iret\n");
 
 #define EH_ENTRY(ec) \
- extern "C" void exception_##ec##_handler(RegisterDumpWithExceptionCode&); \
+ extern "C" void exception_##ec##_handler(RegisterDump&); \
  extern "C" void exception_##ec##_entry(); \
  asm( \
  ".globl exception_" #ec "_entry\n" \
@@ -96,6 +98,7 @@ asm(
  asm( \
  ".globl exception_" #ec "_entry\n" \
  "exception_" #ec "_entry: \n" \
+ " pushl $0x0\n" \
  " pusha\n" \
  " pushw %ds\n" \
  " pushw %es\n" \
@@ -118,10 +121,10 @@ asm(
  " popw %es\n" \
  " popw %ds\n" \
  " popa\n" \
+ " add $0x4, %esp\n" \
  " iret\n");
 
-template<typename DumpType>
-static void dump(const DumpType& regs)
+static void dump(const RegisterDump& regs)
 {
  u16 ss;
  u32 esp;
@@ -133,9 +136,7 @@ static void dump(const DumpType& regs)
  esp = regs.esp_if_crossRing;
  }
 
- if constexpr (IsSame<DumpType, RegisterDumpWithExceptionCode>::value) {
- kprintf("exception code: %04x\n", regs.exception_code);
- }
+ kprintf("exception code: %04x\n", regs.exception_code);
  kprintf(" pc=%04x:%08x ds=%04x es=%04x fs=%04x gs=%04x\n", regs.cs, regs.eip, regs.ds, regs.es, regs.fs, regs.gs);
  kprintf(" stk=%04x:%08x\n", ss, esp);
  if (current)
@@ -157,8 +158,7 @@ static void dump(const DumpType& regs)
  }
 }
 
-template<typename RegisterDumpType>
-static void handle_crash(RegisterDumpType& regs, const char* description, int signal)
+static void handle_crash(RegisterDump& regs, const char* description, int signal)
 {
  if (!current) {
  kprintf("%s with !current\n", description);
@@ -195,7 +195,7 @@ void exception_0_handler(RegisterDump& regs)
 }
 
 EH_ENTRY(13);
-void exception_13_handler(RegisterDumpWithExceptionCode& regs)
+void exception_13_handler(RegisterDump& regs)
 {
  handle_crash(regs, "General protection fault", SIGSEGV);
 }
@@ -232,7 +232,7 @@ void exception_7_handler(RegisterDump& regs)
 
 // 14: Page Fault
 EH_ENTRY(14);
-void exception_14_handler(RegisterDumpWithExceptionCode& regs)
+void exception_14_handler(RegisterDump& regs)
 {
  ASSERT(current);
 

Kernel/Arch/i386/CPU.h

@@ -333,29 +333,6 @@ class PageFault {
 };
 
 struct [[gnu::packed]] RegisterDump
-{
- u16 ss;
- u16 gs;
- u16 fs;
- u16 es;
- u16 ds;
- u32 edi;
- u32 esi;
- u32 ebp;
- u32 esp;
- u32 ebx;
- u32 edx;
- u32 ecx;
- u32 eax;
- u32 eip;
- u16 cs;
- u16 __csPadding;
- u32 eflags;
- u32 esp_if_crossRing;
- u16 ss_if_crossRing;
-};
-
-struct [[gnu::packed]] RegisterDumpWithExceptionCode
 {
  u16 ss;
  u16 gs;
@@ -380,6 +357,7 @@ struct [[gnu::packed]] RegisterDumpWithExceptionCode
  u16 ss_if_crossRing;
 };
 
+
 struct [[gnu::aligned(16)]] FPUState
 {
  u8 buffer[512];

Kernel/Arch/i386/PIT.cpp

@@ -12,6 +12,7 @@ extern "C" void timer_interrupt_handler(RegisterDump&);
 asm(
  ".globl timer_interrupt_entry \n"
  "timer_interrupt_entry: \n"
+ " pushl $0x0\n"
  " pusha\n"
  " pushw %ds\n"
  " pushw %es\n"
@@ -34,6 +35,7 @@ asm(
  " popw %es\n"
  " popw %ds\n"
  " popa\n"
+ " add $0x4, %esp\n"
  " iret\n");
 
 static u32 s_ticks_this_second;

Kernel/Process.cpp

@@ -864,9 +864,12 @@ int Process::sys$sigreturn(RegisterDump& registers)
  current->m_signal_mask = *stack_ptr;
  stack_ptr++;
 
- //pop edi, esi, ebp, esp, ebx, edx, ecx, eax and eip
- memcpy(&registers.edi, stack_ptr, 9 * sizeof(u32));
- stack_ptr += 9;
+ //pop edi, esi, ebp, esp, ebx, edx, ecx and eax
+ memcpy(&registers.edi, stack_ptr, 8 * sizeof(u32));
+ stack_ptr += 8;
+
+ registers.eip = *stack_ptr;
+ stack_ptr++;
 
  registers.eflags = *stack_ptr;
  stack_ptr++;

Kernel/Scheduler.cpp

@@ -561,8 +561,8 @@ void Scheduler::timer_tick(RegisterDump& regs)
  outgoing_tss.eflags = regs.eflags;
 
  // Compute process stack pointer.
- // Add 12 for CS, EIP, EFLAGS (interrupt mechanic)
- outgoing_tss.esp = regs.esp + 12;
+ // Add 16 for CS, EIP, EFLAGS, exception code (interrupt mechanic)
+ outgoing_tss.esp = regs.esp + 16;
  outgoing_tss.ss = regs.ss;
 
  if ((outgoing_tss.cs & 3) != 0) {

Kernel/Syscall.cpp

@@ -13,6 +13,7 @@ extern volatile RegisterDump* syscallRegDump;
 asm(
  ".globl syscall_trap_handler \n"
  "syscall_trap_handler:\n"
+ " pushl $0x0\n"
  " pusha\n"
  " pushw %ds\n"
  " pushw %es\n"
@@ -35,6 +36,7 @@ asm(
  " popw %es\n"
  " popw %ds\n"
  " popa\n"
+ " add $0x4, %esp\n"
  " iret\n");
 
 namespace Syscall {