[debug] Set PMP to create bad address

Author: lz-bro

debug/gdbserver.py

@@ -278,6 +278,9 @@ def test(self):
 class MemTestReadInvalid(SimpleMemoryTest):
     def test(self):
         bad_address = self.hart.bad_address
+        if self.target.support_set_pmp_deny:
+            self.set_pmp_deny(bad_address)
+            self.gdb.command("monitor riscv set_mem_access progbuf abstract")
         good_address = self.hart.ram + 0x80
 
         self.write_nop_program(2)
@@ -293,6 +296,10 @@ def test(self):
         self.gdb.stepi()    # Don't let gdb cache register read
         assertEqual(self.gdb.p(f"*((int*)0x{good_address:x})"), 0xabcdef)
         assertEqual(self.gdb.p("$s0"), 0x12345678)
+        if self.target.support_set_pmp_deny:
+            self.reset_pmp_deny()
+            self.gdb.command("monitor riscv set_mem_access progbuf sysbus "
+                             "abstract")
 
 #class MemTestWriteInvalid(SimpleMemoryTest):
 #    def test(self):
@@ -2182,6 +2189,9 @@ def test(self):
         # Set fox to a bad pointer so we'll get a load access exception later.
         # Use NULL if a known-bad address is not provided.
         bad_address = self.hart.bad_address or 0
+        if self.target.support_set_pmp_deny:
+            self.set_pmp_deny(bad_address)
+            self.gdb.command("monitor riscv set_mem_access progbuf abstract")
         self.gdb.p(f"fox=(char*)0x{bad_address:08x}")
         output = self.gdb.c()
         # We should not be at handle_trap
@@ -2190,6 +2200,10 @@ def test(self):
         # actual exception handler.
         assertIn("breakpoint", output)
         assertIn("trap_entry", self.gdb.where())
+        if self.target.support_set_pmp_deny:
+            self.reset_pmp_deny()
+            self.gdb.command("monitor riscv set_mem_access progbuf sysbus "
+                             "abstract")
 
 class IcountTest(DebugTest):
     compile_args = ("programs/infinite_loop.S", )

debug/targets.py

@@ -141,6 +141,9 @@ class Target:
     # Instruction count limit
     icount_limit = 4
 
+    # Support set_pmp_deny to create invalid addresses.
+    support_set_pmp_deny = False
+
     # Internal variables:
     directory = None
     temporary_files = []

debug/testlib.py

@@ -1485,6 +1485,22 @@ def parkOtherHarts(self, symbol=None):
         self.gdb.select_hart(self.hart)
         self.gdb.command(f"monitor targets {self.hart.id}")
 
+    def set_pmp_deny(self, address, size=4 * 1024):
+        # Enable physical memory protection, no permission to access specific
+        # address range (default 4KB).
+        self.gdb.p("$mseccfg=0x4")  # RLB
+        self.gdb.p("$pmpcfg0=0x98") # L, NAPOT, !R, !W, !X
+        self.gdb.p("$pmpaddr0="
+                       f"0x{((address >> 2) | ((size - 1) >> 3)):x}")
+        # PMP changes require an sfence.vma, 0x12000073 is sfence.vma
+        self.gdb.command("monitor riscv exec_progbuf 0x12000073")
+
+    def reset_pmp_deny(self):
+        self.gdb.p("$pmpcfg0=0")
+        self.gdb.p("$pmpaddr0=0")
+        # PMP changes require an sfence.vma, 0x12000073 is sfence.vma
+        self.gdb.command("monitor riscv exec_progbuf 0x12000073")
+
     def disable_pmp(self):
         # Disable physical memory protection by allowing U mode access to all
         # memory.