[lldb][debugserver] Read/write SME registers on arm64 (#119171)

lldb/source/Plugins/Architecture/AArch64/ArchitectureAArch64.cpp

@@ -100,6 +100,25 @@ bool ArchitectureAArch64::ReconfigureRegisterInfo(DynamicRegisterInfo &reg_info,
     if (reg_value != fail_value && reg_value <= 32)
       svg_reg_value = reg_value;
   }
+  if (!svg_reg_value) {
+    const RegisterInfo *darwin_svg_reg_info = reg_info.GetRegisterInfo("svl");
+    if (darwin_svg_reg_info) {
+      uint32_t svg_reg_num = darwin_svg_reg_info->kinds[eRegisterKindLLDB];
+      uint64_t reg_value =
+          reg_context.ReadRegisterAsUnsigned(svg_reg_num, fail_value);
+      // UpdateARM64SVERegistersInfos and UpdateARM64SMERegistersInfos
+      // expect the number of 8-byte granules; darwin provides number of
+      // bytes.
+      if (reg_value != fail_value && reg_value <= 256) {
+        svg_reg_value = reg_value / 8;
+        // Apple hardware only implements Streaming SVE mode, so
+        // the non-streaming Vector Length is not reported by the
+        // kernel. Set both svg and vg to this svl value.
+        if (!vg_reg_value)
+          vg_reg_value = reg_value / 8;
+      }
+    }
+  }
 
   if (!vg_reg_value && !svg_reg_value)
     return false;

lldb/test/API/commands/register/register/register_command/TestRegisters.py

@@ -21,6 +21,24 @@ def tearDown(self):
         self.dbg.GetSelectedTarget().GetProcess().Destroy()
         TestBase.tearDown(self)
 
+    # on macOS, detect if the current machine is arm64 and supports SME
+    def get_sme_available(self):
+        if self.getArchitecture() != "arm64":
+            return None
+        try:
+            sysctl_output = subprocess.check_output(
+                ["sysctl", "hw.optional.arm.FEAT_SME"]
+            ).decode("utf-8")
+        except subprocess.CalledProcessError:
+            return None
+        m = re.match(r"hw\.optional\.arm\.FEAT_SME: (\w+)", sysctl_output)
+        if m:
+            if int(m.group(1)) == 1:
+                return True
+            else:
+                return False
+        return None
+
     @skipIfiOSSimulator
     @skipIf(archs=no_match(["amd64", "arm", "i386", "x86_64"]))
     @expectedFailureAll(oslist=["freebsd", "netbsd"], bugnumber="llvm.org/pr48371")
@@ -32,11 +50,19 @@ def test_register_commands(self):
         # verify that logging does not assert
         self.log_enable("registers")
 
+        error_str_matched = False
+        if self.get_sme_available() and self.platformIsDarwin():
+            # On Darwin AArch64 SME machines, we will have unavailable
+            # registers when not in Streaming SVE Mode/SME, so
+            # `register read -a` will report that some registers
+            # could not be read.  This is expected.
+            error_str_matched = True
+
         self.expect(
             "register read -a",
             MISSING_EXPECTED_REGISTERS,
             substrs=["registers were unavailable"],
-            matching=False,
+            matching=error_str_matched,
         )
 
         all_registers = self.res.GetOutput()
@@ -60,7 +86,7 @@ def test_register_commands(self):
                 self.runCmd("register read q15")  # may be available
 
         self.expect(
-            "register read -s 4", substrs=["invalid register set index: 4"], error=True
+            "register read -s 8", substrs=["invalid register set index: 8"], error=True
         )
 
     @skipIfiOSSimulator

lldb/test/API/macosx/sme-registers/Makefile

@@ -0,0 +1,5 @@
+C_SOURCES := main.c
+
+CFLAGS_EXTRAS := -mcpu=apple-m4
+
+include Makefile.rules

lldb/test/API/macosx/sme-registers/TestSMERegistersDarwin.py

@@ -0,0 +1,217 @@
+import lldb
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+import lldbsuite.test.lldbutil as lldbutil
+import os
+
+
+class TestSMERegistersDarwin(TestBase):
+    NO_DEBUG_INFO_TESTCASE = True
+    mydir = TestBase.compute_mydir(__file__)
+
+    @skipIfRemote
+    @skipUnlessDarwin
+    @skipUnlessFeature("hw.optional.arm.FEAT_SME")
+    @skipUnlessFeature("hw.optional.arm.FEAT_SME2")
+    # thread_set_state/thread_get_state only avail in macOS 15.4+
+    @skipIf(macos_version=["<", "15.4"])
+    def test(self):
+        """Test that we can read the contents of the SME/SVE registers on Darwin"""
+        self.build()
+        (target, process, thread, bkpt) = lldbutil.run_to_source_breakpoint(
+            self, "break before sme", lldb.SBFileSpec("main.c")
+        )
+        frame = thread.GetFrameAtIndex(0)
+        self.assertTrue(frame.IsValid())
+
+        self.assertTrue(
+            target.BreakpointCreateBySourceRegex(
+                "break while sme", lldb.SBFileSpec("main.c")
+            ).IsValid()
+        )
+        self.assertTrue(
+            target.BreakpointCreateBySourceRegex(
+                "break after sme", lldb.SBFileSpec("main.c")
+            ).IsValid()
+        )
+
+        if self.TraceOn():
+            self.runCmd("reg read -a")
+
+        self.assertTrue(frame.register["svl"].GetError().Fail())
+        self.assertTrue(frame.register["z0"].GetError().Fail())
+        self.assertTrue(frame.register["p0"].GetError().Fail())
+        self.assertTrue(frame.register["za"].GetError().Fail())
+        self.assertTrue(frame.register["zt0"].GetError().Fail())
+
+        process.Continue()
+        frame = thread.GetFrameAtIndex(0)
+        self.assertEqual(thread.GetStopReason(), lldb.eStopReasonBreakpoint)
+
+        # Now in SME enabled mode
+        self.assertTrue(frame.register["svl"].GetError().Success())
+        self.assertTrue(frame.register["z0"].GetError().Success())
+        self.assertTrue(frame.register["p0"].GetError().Success())
+        self.assertTrue(frame.register["za"].GetError().Success())
+        self.assertTrue(frame.register["zt0"].GetError().Success())
+
+        # SSVE and SME modes should be enabled (reflecting PSTATE.SM and PSTATE.ZA)
+        svcr = frame.register["svcr"]
+        self.assertEqual(svcr.GetValueAsUnsigned(), 3)
+
+        svl_reg = frame.register["svl"]
+        svl = svl_reg.GetValueAsUnsigned()
+
+        z0 = frame.register["z0"]
+        self.assertEqual(z0.GetNumChildren(), svl)
+        self.assertEqual(z0.GetChildAtIndex(0).GetValueAsUnsigned(), 0x1)
+        self.assertEqual(z0.GetChildAtIndex(svl - 1).GetValueAsUnsigned(), 0x1)
+
+        z31 = frame.register["z31"]
+        self.assertEqual(z31.GetNumChildren(), svl)
+        self.assertEqual(z31.GetChildAtIndex(0).GetValueAsUnsigned(), 32)
+        self.assertEqual(z31.GetChildAtIndex(svl - 1).GetValueAsUnsigned(), 32)
+
+        p0 = frame.register["p0"]
+        self.assertEqual(p0.GetNumChildren(), svl / 8)
+        self.assertEqual(p0.GetChildAtIndex(0).GetValueAsUnsigned(), 0xFF)
+        self.assertEqual(
+            p0.GetChildAtIndex(p0.GetNumChildren() - 1).GetValueAsUnsigned(), 0xFF
+        )
+
+        p15 = frame.register["p15"]
+        self.assertEqual(p15.GetNumChildren(), svl / 8)
+        self.assertEqual(p15.GetChildAtIndex(0).GetValueAsUnsigned(), 0xFF)
+        self.assertEqual(
+            p15.GetChildAtIndex(p15.GetNumChildren() - 1).GetValueAsUnsigned(), 0xFF
+        )
+
+        za = frame.register["za"]
+        self.assertEqual(za.GetNumChildren(), (svl * svl))
+        za_0 = za.GetChildAtIndex(0)
+        self.assertEqual(za_0.GetValueAsUnsigned(), 4)
+        za_final = za.GetChildAtIndex(za.GetNumChildren() - 1)
+        self.assertEqual(za_final.GetValueAsUnsigned(), 67)
+
+        zt0 = frame.register["zt0"]
+        self.assertEqual(zt0.GetNumChildren(), 64)
+        zt0_0 = zt0.GetChildAtIndex(0)
+        self.assertEqual(zt0_0.GetValueAsUnsigned(), 0)
+        zt0_final = zt0.GetChildAtIndex(63)
+        self.assertEqual(zt0_final.GetValueAsUnsigned(), 63)
+
+        # Modify all of the registers, instruction step, confirm that the
+        # registers have the new values.  Without the instruction step, it's
+        # possible debugserver or lldb could lie about the write succeeding.
+
+        z0_old_values = []
+        z0_new_values = []
+        z0_new_str = '"{'
+        for i in range(svl):
+            z0_old_values.append(z0.GetChildAtIndex(i).GetValueAsUnsigned())
+            z0_new_values.append(z0_old_values[i] + 5)
+            z0_new_str = z0_new_str + ("0x%02x " % z0_new_values[i])
+        z0_new_str = z0_new_str + '}"'
+        self.runCmd("reg write z0 %s" % z0_new_str)
+
+        z31_old_values = []
+        z31_new_values = []
+        z31_new_str = '"{'
+        for i in range(svl):
+            z31_old_values.append(z31.GetChildAtIndex(i).GetValueAsUnsigned())
+            z31_new_values.append(z31_old_values[i] + 3)
+            z31_new_str = z31_new_str + ("0x%02x " % z31_new_values[i])
+        z31_new_str = z31_new_str + '}"'
+        self.runCmd("reg write z31 %s" % z31_new_str)
+
+        p0_old_values = []
+        p0_new_values = []
+        p0_new_str = '"{'
+        for i in range(int(svl / 8)):
+            p0_old_values.append(p0.GetChildAtIndex(i).GetValueAsUnsigned())
+            p0_new_values.append(p0_old_values[i] - 5)
+            p0_new_str = p0_new_str + ("0x%02x " % p0_new_values[i])
+        p0_new_str = p0_new_str + '}"'
+        self.runCmd("reg write p0 %s" % p0_new_str)
+
+        p15_old_values = []
+        p15_new_values = []
+        p15_new_str = '"{'
+        for i in range(int(svl / 8)):
+            p15_old_values.append(p15.GetChildAtIndex(i).GetValueAsUnsigned())
+            p15_new_values.append(p15_old_values[i] - 8)
+            p15_new_str = p15_new_str + ("0x%02x " % p15_new_values[i])
+        p15_new_str = p15_new_str + '}"'
+        self.runCmd("reg write p15 %s" % p15_new_str)
+
+        za_old_values = []
+        za_new_values = []
+        za_new_str = '"{'
+        for i in range(svl * svl):
+            za_old_values.append(za.GetChildAtIndex(i).GetValueAsUnsigned())
+            za_new_values.append(za_old_values[i] + 7)
+            za_new_str = za_new_str + ("0x%02x " % za_new_values[i])
+        za_new_str = za_new_str + '}"'
+        self.runCmd("reg write za %s" % za_new_str)
+
+        zt0_old_values = []
+        zt0_new_values = []
+        zt0_new_str = '"{'
+        for i in range(64):
+            zt0_old_values.append(zt0.GetChildAtIndex(i).GetValueAsUnsigned())
+            zt0_new_values.append(zt0_old_values[i] + 2)
+            zt0_new_str = zt0_new_str + ("0x%02x " % zt0_new_values[i])
+        zt0_new_str = zt0_new_str + '}"'
+        self.runCmd("reg write zt0 %s" % zt0_new_str)
+
+        thread.StepInstruction(False)
+        frame = thread.GetFrameAtIndex(0)
+
+        if self.TraceOn():
+            self.runCmd("reg read -a")
+
+        z0 = frame.register["z0"]
+        for i in range(z0.GetNumChildren()):
+            self.assertEqual(
+                z0_new_values[i], z0.GetChildAtIndex(i).GetValueAsUnsigned()
+            )
+
+        z31 = frame.register["z31"]
+        for i in range(z31.GetNumChildren()):
+            self.assertEqual(
+                z31_new_values[i], z31.GetChildAtIndex(i).GetValueAsUnsigned()
+            )
+
+        p0 = frame.register["p0"]
+        for i in range(p0.GetNumChildren()):
+            self.assertEqual(
+                p0_new_values[i], p0.GetChildAtIndex(i).GetValueAsUnsigned()
+            )
+
+        p15 = frame.register["p15"]
+        for i in range(p15.GetNumChildren()):
+            self.assertEqual(
+                p15_new_values[i], p15.GetChildAtIndex(i).GetValueAsUnsigned()
+            )
+
+        za = frame.register["za"]
+        for i in range(za.GetNumChildren()):
+            self.assertEqual(
+                za_new_values[i], za.GetChildAtIndex(i).GetValueAsUnsigned()
+            )
+
+        zt0 = frame.register["zt0"]
+        for i in range(zt0.GetNumChildren()):
+            self.assertEqual(
+                zt0_new_values[i], zt0.GetChildAtIndex(i).GetValueAsUnsigned()
+            )
+
+        process.Continue()
+        frame = thread.GetFrameAtIndex(0)
+        self.assertEqual(thread.GetStopReason(), lldb.eStopReasonBreakpoint)
+
+        self.assertTrue(frame.register["svl"].GetError().Fail())
+        self.assertTrue(frame.register["z0"].GetError().Fail())
+        self.assertTrue(frame.register["p0"].GetError().Fail())
+        self.assertTrue(frame.register["za"].GetError().Fail())
+        self.assertTrue(frame.register["zt0"].GetError().Fail())