Implement syscalls, hello world from userspace

kernel/hal/x86_64/cpu.c

@@ -1,14 +1,28 @@
 #include <stdint.h>
 #include <stddef.h>
+#include "cpu.h"
+#include "vmm.h"
+#include "pmm/pmm.h"
+#include "hal/hal.h"
+#include "bootinfo/bootinfo.h"
+
+LocalCpuData HAL_CPUS[HAL_CPUS_MAX];
 
 uint64_t hal_cpu_rdmsr(uint32_t id) {
   uint32_t lo, hi;
-  asm volatile("rdmsr" : "=m"(lo), "=d"(hi) : "c"(id));
+  asm volatile("rdmsr" : "=a"(lo), "=d"(hi) : "c"(id));
   return ((uint64_t)lo) | ((uint64_t)hi << 32);
 }
 
 uint64_t hal_cpu_wrmsr(uint32_t id, uint64_t val) {
-  uint32_t lo = val & 0xffffffff, hi = (val >> 32) & 0xffffffff;
-  asm volatile("wrmsr" :: "a"(lo), "d"(hi), "c"(id) : "memory");
+  uint32_t lo = val & 0xFFFFFFFF;
+  uint32_t hi = val >> 32;
+  asm volatile("wrmsr" :: "c"(id), "a"(lo), "d"(hi));
   return val;
 }
+
+void hal_cpu_init(uint32_t cpu) {
+  void *addr = pmm_alloc(16) + (16 * HAL_PAGE_SIZE);
+  HAL_CPUS[cpu].syscall_kstack = (uint64_t *)VIRT(addr);
+  HAL_CPUS[cpu].kcr3 = hal_vmm_current_cr3();
+}

kernel/hal/x86_64/cpu.h

@@ -1,11 +1,36 @@
 #ifndef HAL_CPU_H_
 #define HAL_CPU_H_
 
+#include <stdint.h>
+#include "compiler/attr.h"
+#include "vmm.h"
+#include "intr.h"
+
+#define HAL_CPUS_MAX 0xff
+
+#define HAL_CPU_EFER    0xC0000080
+
+#define HAL_CPU_STAR    0xC0000081
+#define HAL_CPU_LSTAR   0xC0000082
+#define HAL_CPU_CSTAR   0xC0000083
+#define HAL_CPU_SFMASK  0xC0000084
+
 #define HAL_CPU_FSBASE  0xC0000100
 #define HAL_CPU_GSBASE  0xC0000101
 #define HAL_CPU_KGSBASE 0xC0000102
 
+typedef struct {
+  uint64_t *syscall_kstack;
+  uint64_t *syscall_ustack;
+  PgTable *kcr3;
+  PgTable *pcr3;
+  IntrStackFrame *frame;
+} PACKED LocalCpuData;
+
 uint64_t hal_cpu_rdmsr(uint32_t id);
 uint64_t hal_cpu_wrmsr(uint32_t id, uint64_t val);
+void hal_cpu_init(uint32_t cpu);
+
+extern LocalCpuData HAL_CPUS[HAL_CPUS_MAX];
 
 #endif // HAL_CPU_H_

kernel/hal/x86_64/hal.c

@@ -9,6 +9,7 @@
 #include "pic.h"
 #include "apic.h"
 #include "pit.h"
+#include "syscall.h"
 
 void hal_init(void) {
   if (!serial_init()) {
@@ -32,6 +33,7 @@ void hal_init_withmalloc(void) {
   pit_init();
   ioapic_setentry(IOAPIC, acpi_remapirq(0x00), INTR_TIMER);
   hal_intr_disable();
+  hal_syscall_init();
 }
 
 void hal_wait(uint32_t ms) {

kernel/hal/x86_64/intr.c

@@ -133,7 +133,7 @@ void intr_dumpframe(IntrStackFrame *frame) {
   asm volatile("mov %%cr3, %0" : "=r"(cr3));
   uint64_t cr4;
   asm volatile("mov %%cr4, %0" : "=r"(cr4));
-  kprintf_unsafe("rax=%016lx rcx=%016lx rdx=%016lx\n"
+  kprintf("rax=%016lx rcx=%016lx rdx=%016lx\n"
           "rsi=%016lx rdi=%016lx r8 =%016lx\n"
           "r9 =%016lx r10=%016lx r11=%016lx\n"
           "rip=%016lx rfl=%016lx rsp=%016lx\n"
@@ -150,11 +150,14 @@ void intr_dumpframe(IntrStackFrame *frame) {
 }
 
 void intr_handleintr(IntrStackFrame *frame) {
-  if (frame->trapnum >= 0 && frame->trapnum <= 31) {
-    // EXCEPTION
-    kprintf_unsafe("ERROR %s, 0x%lX\n", exceptions[frame->trapnum], frame->errnum);
+  if (frame->trapnum <= 31) {
+    if (frame->trapnum == 14 && frame->errnum & 0x4) {
+      proc_killself();
+      proc_sched((void *)frame);
+    }
+    kprintf("ERROR %s, 0x%lX\n", exceptions[frame->trapnum], frame->errnum);
     intr_dumpframe(frame);
-    hal_hang();  
+    hal_hang();
   } else if (frame->trapnum >= 32 && frame->trapnum <= 47) {
     if (frame->trapnum == INTR_TIMER) {
       io_out8(PIC2_CMD, 0x20);

kernel/hal/x86_64/intr.h

@@ -17,6 +17,7 @@ typedef struct {
   uint64_t r10;
   uint64_t r9;
   uint64_t r8;
+  uint64_t rbp;
   uint64_t rdi;
   uint64_t rsi;
   uint64_t rdx;

kernel/hal/x86_64/intr0.S

@@ -215,4 +215,3 @@ intr_vec46:
 intr_vec47: 
   _vecintr_plain_save 47
   _vecintr_bodygen
-

kernel/hal/x86_64/regs.S

@@ -4,6 +4,7 @@
   push %rdx
   push %rsi
   push %rdi
+  push %rbp
   push %r8
   push %r9
   push %r10
@@ -23,6 +24,7 @@
   pop %r10
   pop %r9
   pop %r8
+  pop %rbp
   pop %rdi
   pop %rsi
   pop %rdx

kernel/hal/x86_64/syscall.c

@@ -0,0 +1,43 @@
+#include <stdint.h>
+#include "syscall.h"
+#include "cpu.h"
+#include "intr.h"
+#include "syscall/syscall.h"
+#include "proc/proc.h"
+#include "kprintf.h"
+#include "errors.h"
+
+extern void hal_enable_syscallentry(void);
+extern void hal_syscallentry(void);
+
+void hal_syscalldispatch(IntrStackFrame *frame) {
+  uint64_t sysnum = frame->regs.rax;
+  if (sysnum < SYSCALLS_MAX) {
+    SyscallFn fn = SYSCALL_TABLE[sysnum];
+    if (fn == NULL) {
+      frame->regs.rax = E_BADSYSCALL;
+      return;
+    }
+    int32_t ret = fn(frame->regs.rdi, frame->regs.rsi, frame->regs.rdx,
+                     frame->regs.r10, frame->regs.r8,  frame->regs.r9);
+
+    if (sysnum == SYS_QUITPROC) {
+      proc_sched((void *)frame);
+    }
+    frame->regs.rax = *(uint64_t *)&ret;
+  }
+}
+
+void hal_syscall_init(void) {
+  hal_cpu_init(0);
+  LocalCpuData *lcd = &HAL_CPUS[0];
+
+  hal_cpu_wrmsr(HAL_CPU_EFER, hal_cpu_rdmsr(HAL_CPU_EFER) | 0x1);
+  hal_enable_syscallentry();
+
+  hal_cpu_wrmsr(HAL_CPU_GSBASE, (uint64_t)lcd);
+  hal_cpu_wrmsr(HAL_CPU_KGSBASE, (uint64_t)lcd);
+  hal_cpu_wrmsr(HAL_CPU_SFMASK, (uint64_t)0);
+
+  hal_cpu_wrmsr(HAL_CPU_LSTAR, (uint64_t)&hal_syscallentry);
+}

kernel/hal/x86_64/syscall.h

@@ -0,0 +1,6 @@
+#ifndef HAL_SYSCALL_H_
+#define HAL_SYSCALL_H_
+
+void hal_syscall_init(void);
+
+#endif // HAL_SYSCALL_H_

kernel/hal/x86_64/syscall0.S

@@ -0,0 +1,48 @@
+#include "regs.S"
+
+.extern hal_syscalldispatch
+
+.global hal_enable_syscallentry
+hal_enable_syscallentry:
+  movq $0xC0000080, %rcx
+  rdmsr
+  or $0x1, %eax
+  wrmsr
+  movq $0xC0000081, %rcx
+  rdmsr
+  movl $0x180008, %edx
+  wrmsr
+  ret
+
+.global hal_syscallentry
+hal_syscallentry:
+  cli
+  swapgs
+
+  movq %rsp, %gs:0x8
+  movq %gs:0x0, %rsp
+
+  pushq $0x23
+  pushq %gs:0x8
+
+  swapgs
+
+  pushq %r11
+  pushq $0x1b
+  pushq %rcx
+
+  _push_regs
+
+  mov %rsp, %rdi
+  mov $0x0, %rbp
+
+  call hal_syscalldispatch
+  cli
+
+  _pop_regs
+
+  popq %rcx
+  add $0x8, %rsp
+  popq %r11
+  popq %rsp
+  sysret