WIP towards ECALL interface for SBI

bbl/bbl.c

@@ -9,68 +9,22 @@
 static kernel_elf_info info;
 static volatile int elf_loaded;
 
-static void supervisor_vm_init()
+void boot_other_hart()
 {
-  uintptr_t highest_va = DRAM_BASE - first_free_paddr;
-  mem_size = MIN(mem_size, highest_va - info.first_user_vaddr) & -MEGAPAGE_SIZE;
-
-  pte_t* sbi_pt = (pte_t*)(info.first_vaddr_after_user + info.load_offset);
-  memset(sbi_pt, 0, RISCV_PGSIZE);
-  pte_t* middle_pt = (void*)sbi_pt + RISCV_PGSIZE;
-#if __riscv_xlen == 32
-  size_t num_middle_pts = 1;
-  pte_t* root_pt = middle_pt;
-  memset(root_pt, 0, RISCV_PGSIZE);
-#else
-  size_t num_middle_pts = (-info.first_user_vaddr - 1) / GIGAPAGE_SIZE + 1;
-  pte_t* root_pt = (void*)middle_pt + num_middle_pts * RISCV_PGSIZE;
-  memset(middle_pt, 0, (num_middle_pts + 1) * RISCV_PGSIZE);
-  for (size_t i = 0; i < num_middle_pts; i++)
-    root_pt[(1<<RISCV_PGLEVEL_BITS)-num_middle_pts+i] = ptd_create(((uintptr_t)middle_pt >> RISCV_PGSHIFT) + i);
-#endif
-
-  for (uintptr_t vaddr = info.first_user_vaddr, paddr = vaddr + info.load_offset, end = info.first_vaddr_after_user;
-       paddr < DRAM_BASE + mem_size; vaddr += MEGAPAGE_SIZE, paddr += MEGAPAGE_SIZE) {
-    int l2_shift = RISCV_PGLEVEL_BITS + RISCV_PGSHIFT;
-    size_t l2_idx = (info.first_user_vaddr >> l2_shift) & ((1 << RISCV_PGLEVEL_BITS)-1);
-    l2_idx += ((vaddr - info.first_user_vaddr) >> l2_shift);
-    middle_pt[l2_idx] = pte_create(paddr >> RISCV_PGSHIFT, PTE_G | PTE_R | PTE_W | PTE_X);
-  }
-
-  // map SBI at top of vaddr space
-  extern char _sbi_end;
-  uintptr_t num_sbi_pages = ((uintptr_t)&_sbi_end - DRAM_BASE - 1) / RISCV_PGSIZE + 1;
-  assert(num_sbi_pages <= (1 << RISCV_PGLEVEL_BITS));
-  for (uintptr_t i = 0; i < num_sbi_pages; i++) {
-    uintptr_t idx = (1 << RISCV_PGLEVEL_BITS) - num_sbi_pages + i;
-    sbi_pt[idx] = pte_create((DRAM_BASE / RISCV_PGSIZE) + i, PTE_G | PTE_R | PTE_X);
-  }
-  pte_t* sbi_pte = middle_pt + ((num_middle_pts << RISCV_PGLEVEL_BITS)-1);
-  assert(!*sbi_pte);
-  *sbi_pte = ptd_create((uintptr_t)sbi_pt >> RISCV_PGSHIFT);
-
+  while (!elf_loaded)
+    ;
   mb();
-  root_page_table = root_pt;
-  write_csr(sptbr, ((uintptr_t)root_pt >> RISCV_PGSHIFT) | SPTBR_MODE);
+  enter_supervisor_mode((void *)info.entry + info.load_offset, read_csr(mhartid), 0);
 }
 
 void boot_loader()
 {
   extern char _payload_start, _payload_end;
   load_kernel_elf(&_payload_start, &_payload_end - &_payload_start, &info);
-  supervisor_vm_init();
 #ifdef PK_ENABLE_LOGO
   print_logo();
 #endif
   mb();
   elf_loaded = 1;
-  enter_supervisor_mode((void *)info.entry, 0);
-}
-
-void boot_other_hart()
-{
-  while (!elf_loaded)
-    ;
-  mb();
-  enter_supervisor_mode((void *)info.entry, 0);
+  boot_other_hart();
 }

dummy_payload/dummy_entry.S

@@ -0,0 +1,22 @@
+#include "mcall.h"
+
+  .section ".text.init"
+  .globl _start
+_start:
+  la s0, str
+1:
+  lbu a0, (s0)
+  beqz a0, 1f
+  li a7, MCALL_CONSOLE_PUTCHAR
+  ecall
+  add s0, s0, 1
+  j 1b
+
+1:
+  li a7, MCALL_SHUTDOWN
+  ecall
+
+  .data
+str:
+  .asciz "This is bbl's dummy_payload.  To boot a real kernel, reconfigure\n\
+bbl with the flag --with-payload=PATH, then rebuild bbl.\n"

dummy_payload/dummy_payload.c

@@ -1,21 +0,0 @@
-#include <stdint.h>
-#include "sbi.h"
-
-asm (".globl _start\n\
-  _start: la sp, stack\n\
-  j entry\n\
-  .pushsection .rodata\n\
-  .align 4\n\
-  .skip 4096\n\
-  stack:\n\
-  .popsection");
-
-void entry()
-{
-  const char* message =
-"This is bbl's dummy_payload.  To boot a real kernel, reconfigure\n\
-bbl with the flag --with-payload=PATH, then rebuild bbl.\n";
-  while (*message)
-    sbi_console_putchar(*message++);
-  sbi_shutdown();
-}

dummy_payload/dummy_payload.lds

@@ -1,3 +1,7 @@
+ENTRY(_start)
+
 SECTIONS {
   . = -0x80000000;
+
+  .text.init : { *(.text.init) }
 }

dummy_payload/dummy_payload.mk.in

@@ -5,7 +5,7 @@ dummy_payload_hdrs = \
 dummy_payload_c_srcs = \
 
 dummy_payload_asm_srcs = \
-  dummy_sbi.S \
+  dummy_entry.S \
 
 dummy_payload_test_srcs =
 

dummy_payload/dummy_sbi.S

@@ -1 +0,0 @@
-../machine/sbi.S

machine/machine.mk.in

@@ -11,7 +11,6 @@ machine_hdrs = \
   htif.h \
   mcall.h \
   mtrap.h \
-  sbi.h \
   unprivileged_memory.h \
   vm.h \
 
@@ -24,11 +23,8 @@ machine_c_srcs = \
   fp_emulation.c \
   fp_ldst.c \
   misaligned_ldst.c \
-  sbi_impl.c \
   configstring.c \
 
 machine_asm_srcs = \
   mentry.S \
   fp_asm.S \
-  sbi_entry.S \
-  sbi.S \

machine/mcall.h

@@ -1,7 +1,6 @@
 #ifndef _RISCV_MCALL_H
 #define _RISCV_MCALL_H
 
-#define MCALL_HART_ID 0
 #define MCALL_CONSOLE_PUTCHAR 1
 #define MCALL_CONSOLE_GETCHAR 2
 #define MCALL_SEND_IPI 4
@@ -11,10 +10,4 @@
 #define MCALL_REMOTE_SFENCE_VM 8
 #define MCALL_REMOTE_FENCE_I 9
 
-#ifndef __ASSEMBLER__
-
-extern uintptr_t do_mcall(uintptr_t which, ...);
-
-#endif
-
 #endif

machine/minit.c

@@ -141,7 +141,7 @@ void init_other_hart()
   boot_other_hart();
 }
 
-void enter_supervisor_mode(void (*fn)(uintptr_t), uintptr_t stack)
+void enter_supervisor_mode(void (*fn)(uintptr_t), uintptr_t arg0, uintptr_t arg1)
 {
   uintptr_t mstatus = read_csr(mstatus);
   mstatus = INSERT_FIELD(mstatus, MSTATUS_MPP, PRV_S);
@@ -149,7 +149,10 @@ void enter_supervisor_mode(void (*fn)(uintptr_t), uintptr_t stack)
   write_csr(mstatus, mstatus);
   write_csr(mscratch, MACHINE_STACK_TOP() - MENTRY_FRAME_SIZE);
   write_csr(mepc, fn);
-  write_csr(sptbr, ((uintptr_t)root_page_table >> RISCV_PGSHIFT) | SPTBR_MODE);
-  asm volatile ("mv a0, %0; mv sp, %0; mret" : : "r" (stack));
+  write_csr(sptbr, 0);
+
+  register uintptr_t a0 asm ("a0") = arg0;
+  register uintptr_t a1 asm ("a1") = arg1;
+  asm volatile ("mret" : : "r" (a0), "r" (a1));
   __builtin_unreachable();
 }

machine/mtrap.c

@@ -13,11 +13,6 @@ void __attribute__((noreturn)) bad_trap()
   die("machine mode: unhandlable trap %d @ %p", read_csr(mcause), read_csr(mepc));
 }
 
-static uintptr_t mcall_hart_id()
-{
-  return read_const_csr(mhartid);
-}
-
 uintptr_t timer_interrupt()
 {
   // just send the timer interrupt to the supervisor
@@ -156,9 +151,6 @@ void mcall_trap(uintptr_t* regs, uintptr_t mcause, uintptr_t mepc)
   uintptr_t n = regs[17], arg0 = regs[10], arg1 = regs[11], retval;
   switch (n)
   {
-    case MCALL_HART_ID:
-      retval = mcall_hart_id();
-      break;
     case MCALL_CONSOLE_PUTCHAR:
       retval = mcall_console_putchar(arg0);
       break;

machine/mtrap.h

@@ -11,7 +11,6 @@
 
 #ifndef __ASSEMBLER__
 
-#include "sbi.h"
 #include <stdint.h>
 #include <stddef.h>
 
@@ -68,7 +67,7 @@ void putstring(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(); })
 
-void enter_supervisor_mode(void (*fn)(uintptr_t), uintptr_t stack)
+void enter_supervisor_mode(void (*fn)(uintptr_t), uintptr_t arg0, uintptr_t arg1)
   __attribute__((noreturn));
 void boot_loader();
 void boot_other_hart();

machine/sbi.S

@@ -1,15 +0,0 @@
-.globl sbi_hart_id; sbi_hart_id = -2048
-.globl sbi_num_harts; sbi_num_harts = -2032
-.globl sbi_query_memory; sbi_query_memory = -2016
-.globl sbi_console_putchar; sbi_console_putchar = -2000
-.globl sbi_console_getchar; sbi_console_getchar = -1984
-.globl sbi_send_ipi; sbi_send_ipi = -1952
-.globl sbi_clear_ipi; sbi_clear_ipi = -1936
-.globl sbi_timebase; sbi_timebase = -1920
-.globl sbi_shutdown; sbi_shutdown = -1904
-.globl sbi_set_timer; sbi_set_timer = -1888
-.globl sbi_mask_interrupt; sbi_mask_interrupt = -1872
-.globl sbi_unmask_interrupt; sbi_unmask_interrupt = -1856
-.globl sbi_remote_sfence_vm; sbi_remote_sfence_vm = -1840
-.globl sbi_remote_sfence_vm_range; sbi_remote_sfence_vm_range = -1824
-.globl sbi_remote_fence_i; sbi_remote_fence_i = -1808

machine/sbi.h

@@ -1,30 +0,0 @@
-#ifndef _ASM_RISCV_SBI_H
-#define _ASM_RISCV_SBI_H
-
-typedef struct {
-  unsigned long base;
-  unsigned long size;
-  unsigned long node_id;
-} memory_block_info;
-
-unsigned long sbi_query_memory(unsigned long id, memory_block_info *p);
-
-unsigned long sbi_hart_id(void);
-unsigned long sbi_num_harts(void);
-unsigned long sbi_timebase(void);
-void sbi_set_timer(unsigned long long stime_value);
-void sbi_send_ipi(unsigned long hart_id);
-unsigned long sbi_clear_ipi(void);
-void sbi_shutdown(void);
-
-void sbi_console_putchar(unsigned char ch);
-int sbi_console_getchar(void);
-
-void sbi_remote_sfence_vm(unsigned long hart_mask_ptr, unsigned long asid);
-void sbi_remote_sfence_vm_range(unsigned long hart_mask_ptr, unsigned long asid, unsigned long start, unsigned long size);
-void sbi_remote_fence_i(unsigned long hart_mask_ptr);
-
-unsigned long sbi_mask_interrupt(unsigned long which);
-unsigned long sbi_unmask_interrupt(unsigned long which);
-
-#endif

machine/sbi_entry.S

@@ -1,111 +0,0 @@
-#include "encoding.h"
-#include "mcall.h"
-
-  .section .sbi,"ax",@progbits
-  .option norvc
-  .align RISCV_PGSHIFT
-  .globl sbi_base
-sbi_base:
-
-  # TODO: figure out something better to do with this space.  It's not
-  # protected from the OS, so beware.
-  .skip RISCV_PGSIZE - 2048
-
-  # hart_id
-  .align 4
-  li a7, MCALL_HART_ID
-  ecall
-  ret
-
-  # num_harts
-  .align 4
-  lw a0, num_harts
-  ret
-
-  # query_memory
-  .align 4
-  tail __sbi_query_memory
-
-  # console_putchar
-  .align 4
-  li a7, MCALL_CONSOLE_PUTCHAR
-  ecall
-  ret
-
-  # console_getchar
-  .align 4
-  li a7, MCALL_CONSOLE_GETCHAR
-  ecall
-  ret
-
-  # empty
-  .align 4
-  unimp
-
-  # send ipi
-  .align 4
-  li a7, MCALL_SEND_IPI
-  ecall
-  ret
-
-  # clear ipi
-  .align 4
-  li a7, MCALL_CLEAR_IPI
-  ecall
-  ret
-
-  # timebase
-  .align 4
-  li a0, 10000000 # or, you know, we could provide the correct answer
-  ret
-
-  # shutdown
-  .align 4
-  li a7, MCALL_SHUTDOWN
-  ecall
-
-  # set_timer
-  .align 4
-  li a7, MCALL_SET_TIMER
-  ecall
-  ret
-
-  # mask_interrupt
-  .align 4
-  tail __sbi_mask_interrupt
-
-  # unmask_interrupt
-  .align 4
-  tail __sbi_unmask_interrupt
-
-  # remote_sfence_vm
-  .align 4
-  li a7, MCALL_REMOTE_SFENCE_VM
-  ecall
-  ret
-
-  # remote_sfence_vm_range
-  .align 4
-  li a7, MCALL_REMOTE_SFENCE_VM
-  ecall
-  ret
-
-  # remote_fence_i
-  .align 4
-  li a7, MCALL_REMOTE_FENCE_I
-  ecall
-  ret
-
-  # end of SBI trampolines
-
-  .globl do_mcall
-do_mcall:
-  mv a7, a0
-  mv a0, a1
-  mv a1, a2
-  ecall
-  ret
-
-  .align RISCV_PGSHIFT
-  .globl _sbi_end
-_sbi_end:

machine/sbi_impl.c

@@ -1,33 +0,0 @@
-#include "mtrap.h"
-#include "sbi.h"
-
-uintptr_t __sbi_query_memory(uintptr_t id, memory_block_info *p)
-{
-  if (id == 0) {
-    p->base = first_free_paddr;
-    p->size = mem_size + DRAM_BASE - p->base;
-    return 0;
-  }
-
-  return -1;
-}
-
-#define LOW_IRQ_OK(n) ((n) == IRQ_S_SOFT || (n) == IRQ_S_TIMER)
-
-uintptr_t __sbi_mask_interrupt(uintptr_t which)
-{
-  if (!LOW_IRQ_OK(which))
-    return -1;
-
-  clear_csr(sie, 1UL << which);
-  return 0;
-}
-
-uintptr_t __sbi_unmask_interrupt(uintptr_t which)
-{
-  if (!LOW_IRQ_OK(which))
-    return -1;
-
-  set_csr(sie, 1UL << which);
-  return 0;
-}

pk/frontend.c

@@ -3,7 +3,6 @@
 #include "pk.h"
 #include "atomic.h"
 #include "frontend.h"
-#include "sbi.h"
 #include "syscall.h"
 #include "htif.h"
 #include <stdint.h>

pk/pk.c

@@ -162,7 +162,7 @@ void boot_loader()
   write_csr(sie, 0);
 
   file_init();
-  enter_supervisor_mode(rest_of_boot_loader, pk_vm_init());
+  enter_supervisor_mode(rest_of_boot_loader, pk_vm_init(), 0);
 }
 
 void boot_other_hart()