Disentangle PK and BBL a bit

21 files changed, 226 insertions, 218 deletions

diff --git a/pk/bbl.c b/pk/bbl.c
index dc6e1ea..031fa08 100644
--- a/pk/bbl.c
+++ b/pk/bbl.c
@@ -1,4 +1,5 @@
-#include "pk.h"
+#include "boot.h"
+#include "mtrap.h"
 #include "vm.h"
 #include "config.h"
 
@@ -15,7 +16,7 @@ static void enter_entry_point()
 void run_loaded_program(struct mainvars* args)
 {
   if (!current.is_supervisor)
-    panic("bbl can't run user binaries; try using pk instead");
+    die("bbl can't run user binaries; try using pk instead");
 
   supervisor_vm_init();
 #ifdef PK_ENABLE_LOGO
diff --git a/pk/bits.h b/pk/bits.h
index 9947351..10f9df3 100644
--- a/pk/bits.h
+++ b/pk/bits.h
@@ -4,6 +4,12 @@
 #define likely(x) __builtin_expect((x), 1)
 #define unlikely(x) __builtin_expect((x), 0)
 
+#define ROUNDUP(a, b) ((((a)-1)/(b)+1)*(b))
+#define ROUNDDOWN(a, b) ((a)/(b)*(b))
+
+#define EXTRACT_FIELD(val, which) (((val) & (which)) / ((which) & ~((which)-1)))
+#define INSERT_FIELD(val, which, fieldval) (((val) & ~(which)) | ((fieldval) * ((which) & ~((which)-1))))
+
 #define CONST_POPCOUNT2(x) ((((x) >> 0) & 1) + (((x) >> 1) & 1))
 #define CONST_POPCOUNT4(x) (CONST_POPCOUNT2(x) + CONST_POPCOUNT2((x)>>2))
 #define CONST_POPCOUNT8(x) (CONST_POPCOUNT4(x) + CONST_POPCOUNT4((x)>>4))
diff --git a/pk/boot.h b/pk/boot.h
new file mode 100644
index 0000000..d0d97d6
--- /dev/null
+++ b/pk/boot.h
@@ -0,0 +1,47 @@
+// See LICENSE for license details.
+
+#ifndef _BOOT_H
+#define _BOOT_H
+
+#ifndef __ASSEMBLER__
+
+#include <stdint.h>
+#include <stddef.h>
+
+struct mainvars {
+  uint64_t argc;
+  uint64_t argv[127]; // this space is shared with the arg strings themselves
+};
+
+typedef struct {
+  int phent;
+  int phnum;
+  int is_supervisor;
+  size_t phdr;
+  size_t phdr_size;
+  size_t first_free_paddr;
+  size_t first_user_vaddr;
+  size_t first_vaddr_after_user;
+  size_t bias;
+  size_t entry;
+  size_t brk_min;
+  size_t brk;
+  size_t brk_max;
+  size_t mmap_max;
+  size_t stack_bottom;
+  size_t stack_top;
+  size_t t0;
+} elf_info;
+
+extern elf_info current;
+
+void prepare_supervisor_mode();
+void run_loaded_program(struct mainvars*);
+void boot_loader();
+void boot_other_hart();
+void load_elf(const char* fn, elf_info* info);
+void print_logo();
+
+#endif // !__ASSEMBLER__
+
+#endif
diff --git a/pk/configstring.c b/pk/configstring.c
index 288d211..847cd4d 100644
--- a/pk/configstring.c
+++ b/pk/configstring.c
@@ -1,5 +1,6 @@
 #include "encoding.h"
 #include "mtrap.h"
+#include <stdio.h>
 
 static const char* skip_whitespace(const char* str)
 {
@@ -163,11 +164,10 @@ static long get_sint(query_result res)
 static void query_mem(const char* config_string)
 {
   query_result res = query_config_string(config_string, "ram{0{addr");
-  kassert(res.start);
+  assert(res.start);
   uintptr_t base = get_uint(res);
   res = query_config_string(config_string, "ram{0{size");
   mem_size = get_uint(res);
-  debug_printk("at %p, found %d MiB of memory\n", base, (int)(mem_size >> 20));
 }
 
 static void query_harts(const char* config_string)
@@ -182,18 +182,19 @@ static void query_harts(const char* config_string)
       csr_t* base = (csr_t*)get_uint(res);
       uintptr_t hart_id = base[CSR_MHARTID];
       hls_init(hart_id, base);
-      debug_printk("at %p, found hart %ld\n", base, hart_id);
-      kassert(num_harts++ == hart_id);
+      num_harts++;
+      assert(hart_id == num_harts-1);
     }
     if (!hart)
       break;
   }
+  assert(num_harts);
+  assert(num_harts <= MAX_HARTS);
 }
 
 void parse_config_string()
 {
   const char* s = (const char*)read_csr(mcfgaddr);
-  debug_printk("%s\n", s);
   query_mem(s);
   query_harts(s);
 }
diff --git a/pk/console.c b/pk/console.c
index 097842b..de7f0a8 100644
--- a/pk/console.c
+++ b/pk/console.c
@@ -3,91 +3,6 @@
 #include "frontend.h"
 #include <stdint.h>
 #include <stdarg.h>
-#include <stdbool.h>
-#include <string.h>
-
-int vsnprintf(char* out, size_t n, const char* s, va_list vl)
-{
-  bool format = false;
-  bool longarg = false;
-  size_t pos = 0;
-  for( ; *s; s++)
-  {
-    if(format)
-    {
-      switch(*s)
-      {
-        case 'l':
-          longarg = true;
-          break;
-        case 'p':
-          longarg = true;
-          if (++pos < n) out[pos-1] = '0';
-          if (++pos < n) out[pos-1] = 'x';
-        case 'x':
-        {
-          long num = longarg ? va_arg(vl, long) : va_arg(vl, int);
-          for(int i = 2*(longarg ? sizeof(long) : sizeof(int))-1; i >= 0; i--) {
-            int d = (num >> (4*i)) & 0xF;
-            if (++pos < n) out[pos-1] = (d < 10 ? '0'+d : 'a'+d-10);
-          }
-          longarg = false;
-          format = false;
-          break;
-        }
-        case 'd':
-        {
-          long num = longarg ? va_arg(vl, long) : va_arg(vl, int);
-          if (num < 0) {
-            num = -num;
-            if (++pos < n) out[pos-1] = '-';
-          }
-          long digits = 1;
-          for (long nn = num; nn /= 10; digits++)
-            ;
-          for (int i = digits-1; i >= 0; i--) {
-            if (pos + i + 1 < n) out[pos + i] = '0' + (num % 10);
-            num /= 10;
-          }
-          pos += digits;
-          longarg = false;
-          format = false;
-          break;
-        }
-        case 's':
-        {
-          const char* s2 = va_arg(vl, const char*);
-          while (*s2) {
-            if (++pos < n)
-              out[pos-1] = *s2;
-            s2++;
-          }
-          longarg = false;
-          format = false;
-          break;
-        }
-        case 'c':
-        {
-          if (++pos < n) out[pos-1] = (char)va_arg(vl,int);
-          longarg = false;
-          format = false;
-          break;
-        }
-        default:
-          panic("bad fmt");
-      }
-    }
-    else if(*s == '%')
-      format = true;
-    else
-      if (++pos < n) out[pos-1] = *s;
-  }
-  if (pos < n)
-    out[pos] = 0;
-  else if (n)
-    out[n-1] = 0;
-  return pos;
-}
 
 static void vprintk(const char* s, va_list vl)
 {
@@ -106,15 +21,6 @@ void printk(const char* s, ...)
   va_end(vl);
 }
 
-int snprintf(char* out, size_t n, const char* s, ...)
-{
-  va_list vl;
-  va_start(vl, s);
-  int res = vsnprintf(out, n, s, vl);
-  va_end(vl);
-  return res;
-}
-
 void dump_tf(trapframe_t* tf)
 {
   static const char* regnames[] = {
@@ -141,7 +47,7 @@ void do_panic(const char* s, ...)
   va_start(vl, s);
 
   vprintk(s, vl);
-  die(-1);
+  shutdown(-1);
 
   va_end(vl);
 }
diff --git a/pk/elf.c b/pk/elf.c
index 5f7210c..7dc783a 100644
--- a/pk/elf.c
+++ b/pk/elf.c
@@ -1,8 +1,9 @@
 // See LICENSE for license details.
 
 #include "file.h"
-#include "pk.h"
 #include "vm.h"
+#include "mtrap.h"
+#include "boot.h"
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <elf.h>
@@ -87,7 +88,7 @@ void load_elf(const char* fn, elf_info* info)
   if (IS_ELF64(eh64))
   {
 #ifndef __riscv64
-    panic("can't run 64-bit ELF on 32-bit arch");
+    die("can't run 64-bit ELF on 32-bit arch");
 #endif
     Elf64_Ehdr* eh;
     Elf64_Phdr* ph;
@@ -96,7 +97,7 @@ void load_elf(const char* fn, elf_info* info)
   else if (IS_ELF32(eh64))
   {
 #ifdef __riscv64
-    panic("can't run 32-bit ELF on 64-bit arch");
+    die("can't run 32-bit ELF on 64-bit arch");
 #endif
     Elf32_Ehdr* eh;
     Elf32_Phdr* ph;
@@ -113,5 +114,5 @@ void load_elf(const char* fn, elf_info* info)
   return;
 
 fail:
-    panic("couldn't open ELF program: %s!", fn);
+    die("couldn't open ELF program: %s!", fn);
 }
diff --git a/pk/emulation.c b/pk/emulation.c
index 4943e0d..c454962 100644
--- a/pk/emulation.c
+++ b/pk/emulation.c
@@ -151,7 +151,7 @@ void misaligned_store_trap(uintptr_t* regs, uintptr_t mcause, uintptr_t mepc)
     return truly_illegal_insn(regs, mcause, mepc, mstatus, insn);
 
   uintptr_t addr = GET_RS1(insn, regs) + IMM_S(insn);
-  for (size_t i = 0; i < len; i++)
+  for (int i = 0; i < len; i++)
     store_uint8_t((void *)(addr + i), val.bytes[i], mepc);
 
   write_csr(mepc, mepc + 4);
diff --git a/pk/frontend.c b/pk/frontend.c
index 5055a28..f0e629f 100644
--- a/pk/frontend.c
+++ b/pk/frontend.c
@@ -32,7 +32,7 @@ long frontend_syscall(long n, long a0, long a1, long a2, long a3, long a4, long
   return ret;
 }
 
-void die(int code)
+void shutdown(int code)
 {
   frontend_syscall(SYS_exit, code, 0, 0, 0, 0, 0, 0);
   while (1);
diff --git a/pk/frontend.h b/pk/frontend.h
index ea5d244..2cf5f81 100644
--- a/pk/frontend.h
+++ b/pk/frontend.h
@@ -18,7 +18,7 @@
 #define FROMHOST_CMD(fromhost_value) ((uint64_t)(fromhost_value) << 8 >> 56)
 #define FROMHOST_DATA(fromhost_value) ((uint64_t)(fromhost_value) << 16 >> 16)
 
-void die(int) __attribute__((noreturn));
+void shutdown(int) __attribute__((noreturn));
 long frontend_syscall(long n, long a0, long a1, long a2, long a3, long a4, long a5, long a6);
 
 struct frontend_stat {
diff --git a/pk/init.c b/pk/init.c
index 57f5fca..6a459f9 100644
--- a/pk/init.c
+++ b/pk/init.c
@@ -1,6 +1,7 @@
 // See LICENSE for license details.
 
 #include "pk.h"
+#include "boot.h"
 #include "file.h"
 #include "vm.h"
 #include "frontend.h"
@@ -43,7 +44,7 @@ static void handle_option(const char* s)
   }
 }
 
-struct mainvars* parse_args(struct mainvars* args)
+static struct mainvars* parse_args(struct mainvars* args)
 {
   long r = frontend_syscall(SYS_getmainvars, (uintptr_t)args, sizeof(*args), 0, 0, 0, 0, 0);
   kassert(r == 0);
@@ -56,8 +57,11 @@ struct mainvars* parse_args(struct mainvars* args)
   return (struct mainvars*)&args->argv[a0-1];
 }
 
-void boot_loader(struct mainvars* args)
+void boot_loader()
 {
+  struct mainvars arg_buffer;
+  struct mainvars *args = parse_args(&arg_buffer);
+
   // load program named by argv[0]
   long phdrs[128];
   current.phdr = (uintptr_t)phdrs;
diff --git a/pk/minit.c b/pk/minit.c
index 42cdfe8..ad9598b 100644
--- a/pk/minit.c
+++ b/pk/minit.c
@@ -1,23 +1,20 @@
 #include "vm.h"
 #include "mtrap.h"
 #include "fp_emulation.h"
+#include "boot.h"
 
 uintptr_t mem_size;
 uint32_t num_harts;
 
 static void mstatus_init()
 {
-  if (!supports_extension('S'))
-    panic("supervisor support is required");
-
   uintptr_t ms = 0;
   ms = INSERT_FIELD(ms, MSTATUS_VM, VM_CHOICE);
   ms = INSERT_FIELD(ms, MSTATUS_FS, 1);
   write_csr(mstatus, ms);
-  ms = read_csr(mstatus);
 
-  if (EXTRACT_FIELD(ms, MSTATUS_VM) != VM_CHOICE)
-    have_vm = 0;
+  ms = read_csr(mstatus);
+  assert(EXTRACT_FIELD(ms, MSTATUS_VM) == VM_CHOICE);
 
   write_csr(mtimecmp, 0);
   clear_csr(mip, MIP_MSIP);
@@ -40,35 +37,23 @@ static void delegate_traps()
 
   write_csr(mideleg, interrupts);
   write_csr(medeleg, exceptions);
-  kassert(read_csr(mideleg) == interrupts);
-  kassert(read_csr(medeleg) == exceptions);
-}
-
-static void memory_init()
-{
-  if (mem_size == 0)
-    panic("could not determine memory capacity");
-
-  if ((intptr_t)mem_size < 0)
-    mem_size = INTPTR_MIN;
-
-  if (num_harts == 0)
-    panic("could not determine number of harts");
+  assert(read_csr(mideleg) == interrupts);
+  assert(read_csr(medeleg) == exceptions);
 }
 
 static void fp_init()
 {
-  kassert(read_csr(mstatus) & MSTATUS_FS);
+  assert(read_csr(mstatus) & MSTATUS_FS);
 
 #ifdef __riscv_hard_float
   if (!supports_extension('D'))
-    panic("FPU not found; recompile pk with -msoft-float");
+    die("FPU not found; recompile pk with -msoft-float");
   for (int i = 0; i < 32; i++)
     init_fp_reg(i);
   write_csr(fcsr, 0);
 #else
   if (supports_extension('D'))
-    panic("FPU unexpectedly found; recompile pk without -msoft-float");
+    die("FPU unexpectedly found; recompile with -mhard-float");
 #endif
 }
 
@@ -93,13 +78,8 @@ void init_first_hart()
 
   memset(HLS(), 0, sizeof(*HLS()));
   parse_config_string();
-
-  struct mainvars arg_buffer;
-  struct mainvars *args = parse_args(&arg_buffer);
-
-  memory_init();
   vm_init();
-  boot_loader(args);
+  boot_loader();
 }
 
 void init_other_hart()
@@ -113,7 +93,7 @@ void init_other_hart()
   write_csr(sptbr, (uintptr_t)root_page_table >> RISCV_PGSHIFT);
 
   // make sure hart 0 has discovered us
-  kassert(HLS()->csrs != NULL);
+  assert(HLS()->csrs != NULL);
 
   boot_other_hart();
 }
diff --git a/pk/mtrap.c b/pk/mtrap.c
index 52b85d8..b64360e 100644
--- a/pk/mtrap.c
+++ b/pk/mtrap.c
@@ -3,10 +3,12 @@
 #include "mcall.h"
 #include "vm.h"
 #include <errno.h>
+#include <stdarg.h>
+#include <stdio.h>
 
 void __attribute__((noreturn)) bad_trap()
 {
-  panic("machine mode: unhandlable trap %d @ %p", read_csr(mcause), read_csr(mepc));
+  die("machine mode: unhandlable trap %d @ %p", read_csr(mcause), read_csr(mepc));
 }
 
 static uintptr_t mcall_hart_id()
@@ -17,14 +19,15 @@ static uintptr_t mcall_hart_id()
 static void request_htif_keyboard_interrupt()
 {
   uintptr_t old_tohost = swap_csr(mtohost, TOHOST_CMD(1, 0, 0));
-  kassert(old_tohost == 0);
+  assert(old_tohost == 0);
 }
 
 void htif_interrupt()
 {
-  // we should only be interrupted by keypresses
   uintptr_t fromhost = swap_csr(mfromhost, 0);
-  kassert(FROMHOST_DEV(fromhost) == 1 && FROMHOST_CMD(fromhost) == 0);
+  // we should only be interrupted by keypresses
+  if (!(FROMHOST_DEV(fromhost) == 1 && FROMHOST_CMD(fromhost) == 0))
+    die("unexpected htif interrupt");
   HLS()->console_ibuf = 1 + (uint8_t)FROMHOST_DATA(fromhost);
   set_csr(mip, MIP_SSIP);
 }
@@ -59,6 +62,12 @@ static uintptr_t mcall_htif_syscall(uintptr_t magic_mem)
   return 0;
 }
 
+void poweroff()
+{
+  while (1)
+    write_csr(mtohost, 1);
+}
+
 void printm(const char* s, ...)
 {
   char buf[256];
@@ -116,9 +125,7 @@ static uintptr_t mcall_clear_ipi()
 
 static uintptr_t mcall_shutdown()
 {
-  while (1)
-    write_csr(mtohost, 1);
-  return 0;
+  poweroff();
 }
 
 static uintptr_t mcall_set_timer(unsigned long long when)
@@ -153,12 +160,10 @@ void software_interrupt()
 
 static void send_ipi_many(uintptr_t* pmask, int event)
 {
-  kassert(MAX_HARTS <= 8 * sizeof(*pmask));
+  _Static_assert(MAX_HARTS <= 8 * sizeof(*pmask), "# harts > uintptr_t bits");
   uintptr_t mask = -1;
-  if (pmask) {
-    kassert(supervisor_paddr_valid((uintptr_t)pmask, sizeof(uintptr_t)));
+  if (pmask)
     mask = *pmask;
-  }
 
   // send IPIs to everyone
   for (ssize_t i = num_harts-1; i >= 0; i--)
@@ -238,7 +243,6 @@ void redirect_trap(uintptr_t epc, uintptr_t mstatus)
 
   uintptr_t prev_priv = EXTRACT_FIELD(mstatus, MSTATUS_MPP);
   uintptr_t prev_ie = EXTRACT_FIELD(mstatus, MSTATUS_MPIE);
-  kassert(prev_priv <= PRV_S);
   mstatus = INSERT_FIELD(mstatus, MSTATUS_SPP, prev_priv);
   mstatus = INSERT_FIELD(mstatus, MSTATUS_SPIE, prev_ie);
   mstatus = INSERT_FIELD(mstatus, MSTATUS_MPP, PRV_S);
diff --git a/pk/mtrap.h b/pk/mtrap.h
index fe44c58..b6ea1df 100644
--- a/pk/mtrap.h
+++ b/pk/mtrap.h
@@ -1,13 +1,19 @@
 #ifndef _PK_MTRAP_H
 #define _PK_MTRAP_H
 
-#include "pk.h"
 #include "bits.h"
 #include "encoding.h"
 
+#ifdef __riscv_atomic
+# define MAX_HARTS 8 // arbitrary
+#else
+# define MAX_HARTS 1
+#endif
+
 #ifndef __ASSEMBLER__
 
 #include "sbi.h"
+#include <stdint.h>
 
 #define read_const_csr(reg) ({ unsigned long __tmp; \
   asm ("csrr %0, " #reg : "=r"(__tmp)); \
@@ -23,6 +29,9 @@ static inline int xlen()
   return read_const_csr(misa) < 0 ? 64 : 32;
 }
 
+extern uintptr_t mem_size;
+extern uint32_t num_harts;
+
 typedef uintptr_t csr_t; // TODO this might become uint128_t for RV128
 
 typedef struct {
@@ -53,7 +62,12 @@ void hls_init(uint32_t hart_id, csr_t* csrs);
 #define HLS() ((hls_t*)(MACHINE_STACK_TOP() - HLS_SIZE))
 #define OTHER_HLS(id) ((hls_t*)((void*)HLS() + RISCV_PGSIZE * ((id) - read_const_csr(mhartid))))
 
-#define printk printm
+void parse_config_string();
+void poweroff(void) __attribute((noreturn));
+void printm(const char* s, ...);
+#define assert(x) ({ if (!(x)) die("assertion failed: %s", #x); })
+#define die(str, ...) ({ printm("%s:%d: " str "\n", __FILE__, __LINE__, ##__VA_ARGS__); poweroff(); })
+#define printk(...) die("printk")
 
 #endif // !__ASSEMBLER__
 
diff --git a/pk/pk.c b/pk/pk.c
index d3f6b3e..8a0e588 100644
--- a/pk/pk.c
+++ b/pk/pk.c
@@ -1,4 +1,5 @@
 #include "pk.h"
+#include "boot.h"
 #include "vm.h"
 #include "elf.h"
 
diff --git a/pk/pk.h b/pk/pk.h
index 917b841..280ad6a 100644
--- a/pk/pk.h
+++ b/pk/pk.h
@@ -3,16 +3,8 @@
 #ifndef _PK_H
 #define _PK_H
 
-#ifdef __riscv_atomic
-# define MAX_HARTS 8 // arbitrary
-#else
-# define MAX_HARTS 1
-#endif
-
 #ifndef __ASSEMBLER__
 
-#define debug_printk(s, ...) //printk(s, __VA_ARGS__)
-
 #include "encoding.h"
 #include <stdint.h>
 #include <string.h>
@@ -28,11 +20,6 @@ typedef struct
   long insn;
 } trapframe_t;
 
-struct mainvars {
-  uint64_t argc;
-  uint64_t argv[127]; // this space is shared with the arg strings themselves
-};
-
 #define panic(s,...) do { do_panic(s"\n", ##__VA_ARGS__); } while(0)
 #define kassert(cond) do { if(!(cond)) kassert_fail(""#cond); } while(0)
 void do_panic(const char* s, ...) __attribute__((noreturn));
@@ -41,18 +28,12 @@ void kassert_fail(const char* s) __attribute__((noreturn));
 #define MIN(a, b) ((a) < (b) ? (a) : (b))
 #define CLAMP(a, lo, hi) MIN(MAX(a, lo), hi)
 
-#define EXTRACT_FIELD(val, which) (((val) & (which)) / ((which) & ~((which)-1)))
-#define INSERT_FIELD(val, which, fieldval) (((val) & ~(which)) | ((fieldval) * ((which) & ~((which)-1))))
-
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-extern uintptr_t mem_size;
 extern int have_vm;
-extern uint32_t num_harts;
 
-struct mainvars* parse_args(struct mainvars*);
 void printk(const char* s, ...);
 void printm(const char* s, ...);
 int vsnprintf(char* out, size_t n, const char* s, va_list vl);
@@ -60,42 +41,12 @@ int snprintf(char* out, size_t n, const char* s, ...);
 void init_tf(trapframe_t*, long pc, long sp);
 void start_user(trapframe_t* tf) __attribute__((noreturn));
 void dump_tf(trapframe_t*);
-void print_logo();
 
 void unhandled_trap(trapframe_t*);
 void handle_misaligned_load(trapframe_t*);
 void handle_misaligned_store(trapframe_t*);
 void handle_fault_load(trapframe_t*);
 void handle_fault_store(trapframe_t*);
-void prepare_supervisor_mode();
-void boot_loader(struct mainvars*);
-void run_loaded_program(struct mainvars*);
-void parse_config_string();
-void boot_other_hart();
-
-typedef struct {
-  int phent;
-  int phnum;
-  int is_supervisor;
-  size_t phdr;
-  size_t phdr_size;
-  size_t first_free_paddr;
-  size_t first_user_vaddr;
-  size_t first_vaddr_after_user;
-  size_t bias;
-  size_t entry;
-  size_t brk_min;
-  size_t brk;
-  size_t brk_max;
-  size_t mmap_max;
-  size_t stack_bottom;
-  size_t stack_top;
-  size_t t0;
-} elf_info;
-
-extern elf_info current;
-
-void load_elf(const char* fn, elf_info* info);
 
 static inline int insn_len(long insn)
 {
@@ -120,7 +71,4 @@ static inline void wfi()
 
 #endif // !__ASSEMBLER__
 
-#define ROUNDUP(a, b) ((((a)-1)/(b)+1)*(b))
-#define ROUNDDOWN(a, b) ((a)/(b)*(b))
-
 #endif
diff --git a/pk/pk.mk.in b/pk/pk.mk.in
index 0189666..78f826e 100644
--- a/pk/pk.mk.in
+++ b/pk/pk.mk.in
@@ -4,6 +4,7 @@ pk_subproject_deps = \
 pk_hdrs = \
 	atomic.h \
 	bits.h \
+	boot.h \
 	elf.h \
 	emulation.h \
 	encoding.h \
@@ -19,6 +20,7 @@ pk_hdrs = \
 	vm.h \
 
 pk_c_srcs = \
+	snprintf.c \
 	mtrap.c \
 	minit.c \
 	emulation.c \
diff --git a/pk/sbi_impl.c b/pk/sbi_impl.c
index bd352fe..4af0cd4 100644
--- a/pk/sbi_impl.c
+++ b/pk/sbi_impl.c
@@ -1,9 +1,6 @@
-#include "pk.h"
-#include "vm.h"
-#include "frontend.h"
+#include "mtrap.h"
 #include "sbi.h"
-#include "mcall.h"
-#include <errno.h>
+#include "boot.h"
 
 uintptr_t __sbi_query_memory(uintptr_t id, memory_block_info *p)
 {
diff --git a/pk/snprintf.c b/pk/snprintf.c
new file mode 100644
index 0000000..1544a6c
--- /dev/null
+++ b/pk/snprintf.c
@@ -0,0 +1,98 @@
+// See LICENSE for license details.
+
+#include <stdint.h>
+#include <string.h>
+#include <stdarg.h>
+#include <stdbool.h>
+
+int vsnprintf(char* out, size_t n, const char* s, va_list vl)
+{
+  bool format = false;
+  bool longarg = false;
+  size_t pos = 0;
+  for( ; *s; s++)
+  {
+    if(format)
+    {
+      switch(*s)
+      {
+        case 'l':
+          longarg = true;
+          break;
+        case 'p':
+          longarg = true;
+          if (++pos < n) out[pos-1] = '0';
+          if (++pos < n) out[pos-1] = 'x';
+        case 'x':
+        {
+          long num = longarg ? va_arg(vl, long) : va_arg(vl, int);
+          for(int i = 2*(longarg ? sizeof(long) : sizeof(int))-1; i >= 0; i--) {
+            int d = (num >> (4*i)) & 0xF;
+            if (++pos < n) out[pos-1] = (d < 10 ? '0'+d : 'a'+d-10);
+          }
+          longarg = false;
+          format = false;
+          break;
+        }
+        case 'd':
+        {
+          long num = longarg ? va_arg(vl, long) : va_arg(vl, int);
+          if (num < 0) {
+            num = -num;
+            if (++pos < n) out[pos-1] = '-';
+          }
+          long digits = 1;
+          for (long nn = num; nn /= 10; digits++)
+            ;
+          for (int i = digits-1; i >= 0; i--) {
+            if (pos + i + 1 < n) out[pos + i] = '0' + (num % 10);
+            num /= 10;
+          }
+          pos += digits;
+          longarg = false;
+          format = false;
+          break;
+        }
+        case 's':
+        {
+          const char* s2 = va_arg(vl, const char*);
+          while (*s2) {
+            if (++pos < n)
+              out[pos-1] = *s2;
+            s2++;
+          }
+          longarg = false;
+          format = false;
+          break;
+        }
+        case 'c':
+        {
+          if (++pos < n) out[pos-1] = (char)va_arg(vl,int);
+          longarg = false;
+          format = false;
+          break;
+        }
+        default:
+          break;
+      }
+    }
+    else if(*s == '%')
+      format = true;
+    else
+      if (++pos < n) out[pos-1] = *s;
+  }
+  if (pos < n)
+    out[pos] = 0;
+  else if (n)
+    out[n-1] = 0;
+  return pos;
+}
+
+int snprintf(char* out, size_t n, const char* s, ...)
+{
+  va_list vl;
+  va_start(vl, s);
+  int res = vsnprintf(out, n, s, vl);
+  va_end(vl);
+  return res;
+}
diff --git a/pk/syscall.c b/pk/syscall.c
index 6af78ee..17112d8 100644
--- a/pk/syscall.c
+++ b/pk/syscall.c
@@ -5,6 +5,7 @@
 #include "file.h"
 #include "frontend.h"
 #include "vm.h"
+#include "boot.h"
 #include <string.h>
 #include <errno.h>
 
@@ -41,7 +42,7 @@ void sys_exit(int code)
     }
   }
 
-  die(code);
+  shutdown(code);
 }
 
 ssize_t sys_read(int fd, char* buf, size_t n)
diff --git a/pk/vm.c b/pk/vm.c
index 3f5cb30..c29434d 100644
--- a/pk/vm.c
+++ b/pk/vm.c
@@ -2,6 +2,8 @@
 #include "file.h"
 #include "atomic.h"
 #include "pk.h"
+#include "boot.h"
+#include "mtrap.h"
 #include <stdint.h>
 #include <errno.h>
 
diff --git a/pk/vm.h b/pk/vm.h
index 4a24e56..c05a1ce 100644
--- a/pk/vm.h
+++ b/pk/vm.h
@@ -28,11 +28,6 @@
 #define MAP_POPULATE 0x8000
 #define MREMAP_FIXED 0x2
 
-#define supervisor_paddr_valid(start, length) \
-  ((uintptr_t)(start) >= current.first_user_vaddr + current.bias \
-   && (uintptr_t)(start) + (length) < mem_size \
-   && (uintptr_t)(start) + (length) >= (uintptr_t)(start))
-
 void vm_init();
 void supervisor_vm_init();
 uintptr_t pk_vm_init();