conservatively call sfence.vma before every satp load.

1 files changed, 11 insertions, 0 deletions

diff --git a/kernel/riscv.h b/kernel/riscv.h
index e5c0f64..e35f3bc 100644
--- a/kernel/riscv.h
+++ b/kernel/riscv.h
@@ -312,6 +312,17 @@ r_ra()
   return x;
 }
 
+// tell the machine to finish any previous writes to
+// PTEs, so that a subsequent use of a virtual
+// address or load of the SATP will see those writes.
+// perhaps this also flushes the TLB.
+static inline void
+sfence_vma()
+{
+  // the zero, zero means flush all TLB entries.
+  asm volatile("sfence.vma zero, zero");
+}
+
 
 #define PGSIZE 4096 // bytes per page
 #define PGSHIFT 12  // bits of offset within a page