env: trap and page fault filter mechanism (riscv#40)

Certain tests (particularly negative) may require a fault to occur. However in order to pass the tests, page fault and traps must return back to the tests. This patch add support for page fault and trap filtering in env. Signed-off-by: Deepak Gupta <[email protected]>
Timmmm · Feb 2, 2023 · 982f93f · 982f93f
1 parent 34a1175
commit 982f93f
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Showing 3 changed files with 27 additions and 0 deletions.
diff --git a/p/riscv_test.h b/p/riscv_test.h
@@ -153,6 +153,8 @@
 #define EXTRA_TVEC_MACHINE
 #define EXTRA_INIT
 #define EXTRA_INIT_TIMER
+#define FILTER_TRAP
+#define FILTER_PAGE_FAULT
 
 #define INTERRUPT_HANDLER j other_exception /* No interrupts should occur */
 

diff --git a/v/riscv_test.h b/v/riscv_test.h
@@ -24,6 +24,16 @@
 extra_boot:                                                             \
         EXTRA_INIT                                                      \
         ret;                                                            \
+.global trap_filter;                                                    \
+trap_filter:                                                            \
+        FILTER_TRAP                                                     \
+        li a0, 0;                                                       \
+        ret;                                                            \
+.global pf_filter;                                                      \
+pf_filter:                                                              \
+        FILTER_PAGE_FAULT                                               \
+        li a0, 0;                                                       \
+        ret;                                                            \
         .global userstart;                                              \
 userstart:                                                              \
         init

diff --git a/v/vm.c b/v/vm.c
@@ -136,8 +136,14 @@ static void evict(unsigned long addr)
   }
 }
 
+extern int pf_filter(uintptr_t addr, uintptr_t *pte, int *copy);
+extern int trap_filter(trapframe_t *tf);
+
 void handle_fault(uintptr_t addr, uintptr_t cause)
 {
+  uintptr_t filter_encodings = 0;
+  int copy_page = 1;
+
   assert(addr >= PGSIZE && addr < MAX_TEST_PAGES * PGSIZE);
   addr = addr/PGSIZE*PGSIZE;
 
@@ -159,6 +165,11 @@ void handle_fault(uintptr_t addr, uintptr_t cause)
     freelist_tail = 0;
 
   uintptr_t new_pte = (node->addr >> PGSHIFT << PTE_PPN_SHIFT) | PTE_V | PTE_U | PTE_R | PTE_W | PTE_X;
+
+  if (pf_filter(addr, &filter_encodings, &copy_page)) {
+      new_pte = (node->addr >> PGSHIFT << PTE_PPN_SHIFT) | filter_encodings;
+  }
+
   user_llpt[addr/PGSIZE] = new_pte | PTE_A | PTE_D;
   flush_page(addr);
 
@@ -177,6 +188,10 @@ void handle_fault(uintptr_t addr, uintptr_t cause)
 
 void handle_trap(trapframe_t* tf)
 {
+  if (trap_filter(tf)) {
+    pop_tf(tf);
+  }
+
   if (tf->cause == CAUSE_USER_ECALL)
   {
     int n = tf->gpr[10];