Merge branch 'cow' into net

Conflicts:
	.gitignore
	Makefile
	conf/lab.mk
	kernel/defs.h
	kernel/syscall.c
	kernel/vm.c
	user/pingpong.c
	user/user.h
	user/usys.pl

1 files changed, 11 insertions, 0 deletions

diff --git a/kernel/riscv.h b/kernel/riscv.h
index 20a01db..7d6eb6e 100644
--- a/kernel/riscv.h
+++ b/kernel/riscv.h
@@ -327,6 +327,15 @@ sfence_vma()
   asm volatile("sfence.vma zero, zero");
 }
 
+// read the frame pointer of currently executing func
+static inline uint64
+r_fp()
+{
+  uint64 x;
+  asm volatile("mv %0, s0" : "=r" (x) );
+  return x;
+}
+
 typedef uint64 pte_t;
 typedef uint64 *pagetable_t; // 512 PTEs
 
@@ -343,6 +352,8 @@ typedef uint64 *pagetable_t; // 512 PTEs
 #define PTE_W (1L << 2)
 #define PTE_X (1L << 3)
 #define PTE_U (1L << 4) // user can access
+#define PTE_A (1L << 6) // riscv access bit                      
+#define PTE_C (1L << 8) // RSW low bit, use it to mark whether a page is COW
 
 // shift a physical address to the right place for a PTE.
 #define PA2PTE(pa) ((((uint64)pa) >> 12) << 10)