From 23ab37ad78673166a8300584d177ace77fca5101 Mon Sep 17 00:00:00 2001
From: "Wesley W. Terpstra" <wesley@sifive.com>
Date: Wed, 22 Mar 2017 14:35:13 -0700
Subject: SBI: a0+a1 hold hartid+dtb pointer between boot loader stages

---
 bbl/bbl.c        |  8 ++++----
 machine/mentry.S | 27 ++++++++++++++-------------
 machine/minit.c  | 16 +++++++---------
 machine/mtrap.h  |  4 ++--
 pk/pk.c          |  6 +++---
 5 files changed, 30 insertions(+), 31 deletions(-)

diff --git a/bbl/bbl.c b/bbl/bbl.c
index 9553ddb..3550c9a 100644
--- a/bbl/bbl.c
+++ b/bbl/bbl.c
@@ -8,17 +8,17 @@
 
 static const void* entry_point;
 
-void boot_other_hart()
+void boot_other_hart(uintptr_t dtb)
 {
   const void* entry;
   do {
     entry = entry_point;
     mb();
   } while (!entry);
-  enter_supervisor_mode(entry, read_csr(mhartid), 0);
+  enter_supervisor_mode(entry, read_csr(mhartid), dtb);
 }
 
-void boot_loader()
+void boot_loader(uintptr_t dtb)
 {
   extern char _payload_start;
 #ifdef PK_ENABLE_LOGO
@@ -26,5 +26,5 @@ void boot_loader()
 #endif
   mb();
   entry_point = &_payload_start;
-  boot_other_hart();
+  boot_other_hart(dtb);
 }
diff --git a/machine/mentry.S b/machine/mentry.S
index 01db536..9ce3257 100644
--- a/machine/mentry.S
+++ b/machine/mentry.S
@@ -217,8 +217,9 @@ do_reset:
   li x7, 0
   li x8, 0
   li x9, 0
-  li x10, 0
-  li x11, 0
+// save a0 and a1; arguments from previous boot loader stage:
+//  li x10, 0
+//  li x11, 0
   li x12, 0
   li x13, 0
   li x14, 0
@@ -249,28 +250,28 @@ do_reset:
 
   la sp, stacks + RISCV_PGSIZE - MENTRY_FRAME_SIZE
 
-  csrr a0, mhartid
-  slli a1, a0, RISCV_PGSHIFT
-  add sp, sp, a1
+  csrr a3, mhartid
+  slli a2, a3, RISCV_PGSHIFT
+  add sp, sp, a2
 
-  beqz a0, init_first_hart
+  beqz a3, init_first_hart
 
   # set MSIE bit to receive IPI
-  li a1, MIP_MSIP
-  csrw mie, a1
+  li a2, MIP_MSIP
+  csrw mie, a2
 
 .LmultiHart:
 #if MAX_HARTS > 1
   # wait for an IPI to signal that it's safe to boot
   wfi
-  csrr a1, mip
-  andi a1, a1, MIP_MSIP
-  beqz a1, .LmultiHart
+  csrr a2, mip
+  andi a2, a2, MIP_MSIP
+  beqz a2, .LmultiHart
 
   # make sure our hart id is within a valid range
   fence
-  li a1, MAX_HARTS
-  bltu a0, a1, init_other_hart
+  li a2, MAX_HARTS
+  bltu a3, a2, init_other_hart
 #endif
   wfi
   j .LmultiHart
diff --git a/machine/minit.c b/machine/minit.c
index 2616f19..f02f205 100644
--- a/machine/minit.c
+++ b/machine/minit.c
@@ -72,8 +72,6 @@ hls_t* hls_init(uintptr_t id)
   return hls;
 }
 
-#define DTB 0x1014
-
 static void memory_init()
 {
   mem_size = mem_size / MEGAPAGE_SIZE * MEGAPAGE_SIZE;
@@ -122,27 +120,27 @@ static void hart_plic_init()
   *HLS()->plic_s_thresh = 0;
 }
 
-void init_first_hart()
+void init_first_hart(uintptr_t hartid, uintptr_t dtb)
 {
   hart_init();
   hls_init(0); // this might get called again from parse_config_string
 
-  query_mem(DTB);
-  query_harts(DTB);
-  query_clint(DTB);
+  query_mem(dtb);
+  query_harts(dtb);
+  query_clint(dtb);
 
   plic_init();
   hart_plic_init();
   //prci_test();
   memory_init();
-  boot_loader();
+  boot_loader(dtb);
 }
 
-void init_other_hart()
+void init_other_hart(uintptr_t hartid, uintptr_t dtb)
 {
   hart_init();
   hart_plic_init();
-  boot_other_hart();
+  boot_other_hart(dtb);
 }
 
 void enter_supervisor_mode(void (*fn)(uintptr_t), uintptr_t arg0, uintptr_t arg1)
diff --git a/machine/mtrap.h b/machine/mtrap.h
index 2f0fc69..e8dfc49 100644
--- a/machine/mtrap.h
+++ b/machine/mtrap.h
@@ -64,8 +64,8 @@ void putstring(const char* s);
 
 void enter_supervisor_mode(void (*fn)(uintptr_t), uintptr_t arg0, uintptr_t arg1)
   __attribute__((noreturn));
-void boot_loader();
-void boot_other_hart();
+void boot_loader(uintptr_t dtb);
+void boot_other_hart(uintptr_t dtb);
 
 static inline void wfi()
 {
diff --git a/pk/pk.c b/pk/pk.c
index c0b6407..1a2e540 100644
--- a/pk/pk.c
+++ b/pk/pk.c
@@ -154,7 +154,7 @@ static void rest_of_boot_loader(uintptr_t kstack_top)
   run_loaded_program(argc, args.argv, kstack_top);
 }
 
-void boot_loader()
+void boot_loader(uintptr_t dtb)
 {
   extern char trap_entry;
   write_csr(stvec, &trap_entry);
@@ -163,10 +163,10 @@ void boot_loader()
   set_csr(sstatus, SSTATUS_SUM);
 
   file_init();
-  enter_supervisor_mode(rest_of_boot_loader, pk_vm_init(), 0);
+  enter_supervisor_mode(rest_of_boot_loader, pk_vm_init(), dtb);
 }
 
-void boot_other_hart()
+void boot_other_hart(uintptr_t dtb)
 {
   // stall all harts besides hart 0
   while (1)
-- 
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