Skip to content

[lldb][AArch64][Linux] Add fields for FPCR register #71694

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Nov 9, 2023

Conversation

DavidSpickett
Copy link
Collaborator

Follows the format laid out in the Arm manual, AArch32 only fields are ignored.

(lldb) register read fpcr
    fpcr = 0x00000000
         = (AHP = 0, DN = 0, FZ = 0, RMMode = 0, FZ16 = 0, IDE = 0, IXE = 0, UFE = 0, OFE = 0, DZE = 0, IOE = 0)

Tests use the first 4 fields that we know are always present.

Converted all the HCWAP defines to UL because I'm bound to
forget one if I don't do it now.

@llvmbot
Copy link
Member

llvmbot commented Nov 8, 2023

@llvm/pr-subscribers-lldb

Author: David Spickett (DavidSpickett)

Changes

Follows the format laid out in the Arm manual, AArch32 only fields are ignored.

(lldb) register read fpcr
    fpcr = 0x00000000
         = (AHP = 0, DN = 0, FZ = 0, RMMode = 0, FZ16 = 0, IDE = 0, IXE = 0, UFE = 0, OFE = 0, DZE = 0, IOE = 0)

Tests use the first 4 fields that we know are always present.

Converted all the HCWAP defines to UL because I'm bound to
forget one if I don't do it now.


Full diff: https://github.com/llvm/llvm-project/pull/71694.diff

4 Files Affected:

  • (modified) lldb/source/Plugins/Process/Utility/RegisterFlagsLinux_arm64.cpp (+64-4)
  • (modified) lldb/source/Plugins/Process/Utility/RegisterFlagsLinux_arm64.h (+5-1)
  • (modified) lldb/test/API/commands/register/register/register_command/TestRegisters.py (+7-2)
  • (modified) lldb/test/API/functionalities/postmortem/elf-core/TestLinuxCore.py (+5)
diff --git a/lldb/source/Plugins/Process/Utility/RegisterFlagsLinux_arm64.cpp b/lldb/source/Plugins/Process/Utility/RegisterFlagsLinux_arm64.cpp
index 043789bd6d21e47..ba1a0d5599e7703 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterFlagsLinux_arm64.cpp
+++ b/lldb/source/Plugins/Process/Utility/RegisterFlagsLinux_arm64.cpp
@@ -12,14 +12,74 @@
 // This file is built on all systems because it is used by native processes and
 // core files, so we manually define the needed HWCAP values here.
 
-#define HWCAP_DIT (1 << 24)
-#define HWCAP_SSBS (1 << 28)
+#define HWCAP_FPHP (1UL << 9)
+#define HWCAP_ASIMDHP (1UL << 10)
+#define HWCAP_DIT (1UL << 24)
+#define HWCAP_SSBS (1UL << 28)
 
-#define HWCAP2_BTI (1 << 17)
-#define HWCAP2_MTE (1 << 18)
+#define HWCAP2_BTI (1UL << 17)
+#define HWCAP2_MTE (1UL << 18)
+#define HWCAP2_AFP (1UL << 20)
+#define HWCAP2_EBF16 (1UL << 32)
 
 using namespace lldb_private;
 
+LinuxArm64RegisterFlags::Fields
+LinuxArm64RegisterFlags::DetectFPCRFields(uint64_t hwcap, uint64_t hwcap2) {
+  std::vector<RegisterFlags::Field> fpcr_fields{
+      {"AHP", 26}, {"DN", 25}, {"FZ", 24}, {"RMMode", 22, 23},
+      // Bits 21-20 are "Stride" which is unused in AArch64 state.
+  };
+
+  // FEAT_FP16 is indicated by the presence of FPHP (floating point half
+  // precision) and ASIMDHP (Advanced SIMD half precision) features.
+  if ((hwcap & HWCAP_FPHP) && (hwcap & HWCAP_ASIMDHP))
+    fpcr_fields.push_back({"FZ16", 19});
+
+  // Bits 18-16 are "Len" which is unused in AArch64 state.
+
+  fpcr_fields.push_back({"IDE", 15});
+
+  // Bit 14 is unused.
+  if (hwcap2 & HWCAP2_EBF16)
+    fpcr_fields.push_back({"EBF", 13});
+
+  fpcr_fields.push_back({"IXE", 12});
+  fpcr_fields.push_back({"UFE", 11});
+  fpcr_fields.push_back({"OFE", 10});
+  fpcr_fields.push_back({"DZE", 9});
+  fpcr_fields.push_back({"IOE", 8});
+  // Bits 7-3 reserved.
+
+  if (hwcap2 & HWCAP2_AFP) {
+    fpcr_fields.push_back({"NEP", 2});
+    fpcr_fields.push_back({"AH", 1});
+    fpcr_fields.push_back({"FIZ", 0});
+  }
+
+  return fpcr_fields;
+}
+
+LinuxArm64RegisterFlags::Fields
+LinuxArm64RegisterFlags::DetectFPSRFields(uint64_t hwcap, uint64_t hwcap2) {
+  // fpsr's contents are constant.
+  (void)hwcap;
+  (void)hwcap2;
+
+  return {
+      // Bits 31-28 are N/Z/C/V, only used by AArch32.
+      {"QC", 27},
+      // Bits 26-8 reserved.
+      {"IDC", 7},
+      // Bits 6-5 reserved.
+      {"IXC", 4},
+      {"UFC", 3},
+      {"OFC", 2},
+      {"DZC", 1},
+      {"IOC", 0},
+  };
+}
+
 LinuxArm64RegisterFlags::Fields
 LinuxArm64RegisterFlags::DetectCPSRFields(uint64_t hwcap, uint64_t hwcap2) {
   // The fields here are a combination of the Arm manual's SPSR_EL1,
diff --git a/lldb/source/Plugins/Process/Utility/RegisterFlagsLinux_arm64.h b/lldb/source/Plugins/Process/Utility/RegisterFlagsLinux_arm64.h
index 6c7a3b61a1425ee..651a8c86f7c86a9 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterFlagsLinux_arm64.h
+++ b/lldb/source/Plugins/Process/Utility/RegisterFlagsLinux_arm64.h
@@ -56,6 +56,8 @@ class LinuxArm64RegisterFlags {
   using DetectorFn = std::function<Fields(uint64_t, uint64_t)>;
 
   static Fields DetectCPSRFields(uint64_t hwcap, uint64_t hwcap2);
+  static Fields DetectFPSRFields(uint64_t hwcap, uint64_t hwcap2);
+  static Fields DetectFPCRFields(uint64_t hwcap, uint64_t hwcap2);
 
   struct RegisterEntry {
     RegisterEntry(llvm::StringRef name, unsigned size, DetectorFn detector)
@@ -65,8 +67,10 @@ class LinuxArm64RegisterFlags {
     llvm::StringRef m_name;
     RegisterFlags m_flags;
     DetectorFn m_detector;
-  } m_registers[1] = {
+  } m_registers[3] = {
       RegisterEntry("cpsr", 4, DetectCPSRFields),
+      RegisterEntry("fpsr", 4, DetectFPSRFields),
+      RegisterEntry("fpcr", 4, DetectFPCRFields),
   };
 
   // Becomes true once field detection has been run for all registers.
diff --git a/lldb/test/API/commands/register/register/register_command/TestRegisters.py b/lldb/test/API/commands/register/register/register_command/TestRegisters.py
index f29b2ab5d8f259d..386991c18db7c8c 100644
--- a/lldb/test/API/commands/register/register/register_command/TestRegisters.py
+++ b/lldb/test/API/commands/register/register/register_command/TestRegisters.py
@@ -622,13 +622,18 @@ def test_info_register(self):
     @skipUnlessPlatform(["linux"])
     @skipIf(archs=no_match(["aarch64"]))
     def test_register_read_fields(self):
-        """Test that when debugging a live process, we see the fields of the
-        CPSR register."""
+        """Test that when debugging a live process, we see the fields of certain
+        registers."""
         self.build()
         self.common_setup()
 
         # N/Z/C/V bits will always be present, so check only for those.
         self.expect("register read cpsr", substrs=["= (N = 0, Z = 1, C = 1, V = 0"])
+        self.expect("register read fpsr", substrs=["= (QC = 0, IDC = 0, IXC = 0"])
+        # AHP/DN/FZ/RMMode always present, others may vary.
+        self.expect(
+            "register read fpcr", substrs=["= (AHP = 0, DN = 0, FZ = 0, RMMode = 0"]
+        )
 
     @skipUnlessPlatform(["linux"])
     @skipIf(archs=no_match(["x86_64"]))
diff --git a/lldb/test/API/functionalities/postmortem/elf-core/TestLinuxCore.py b/lldb/test/API/functionalities/postmortem/elf-core/TestLinuxCore.py
index a083fab18eabcbc..58f104eb49de245 100644
--- a/lldb/test/API/functionalities/postmortem/elf-core/TestLinuxCore.py
+++ b/lldb/test/API/functionalities/postmortem/elf-core/TestLinuxCore.py
@@ -577,6 +577,11 @@ def test_aarch64_sve_regs_full(self):
         # Register field information should work with core files as it does a live process.
         # The N/Z/C/V bits are always present so just check for those.
         self.expect("register read cpsr", substrs=["= (N = 0, Z = 0, C = 0, V = 0"])
+        self.expect("register read fpsr", substrs=["= (QC = 0, IDC = 0, IXC = 0"])
+        # AHP/DN/FZ/RMMode always present, others may vary.
+        self.expect(
+            "register read fpcr", substrs=["= (AHP = 0, DN = 0, FZ = 0, RMMode = 0"]
+        )
 
     @skipIfLLVMTargetMissing("AArch64")
     def test_aarch64_pac_regs(self):

@DavidSpickett
Copy link
Collaborator Author

First commit is actually #71651, so look at the second one only.

Copy link
Member

@bulbazord bulbazord left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This also looks pretty straightforward after you implemented the initial support. :)

Copy link
Collaborator

@jasonmolenda jasonmolenda left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

lgtm

Follows the format laid out in the Arm manual, AArch32 only fields are ignored.

```
(lldb) register read fpcr
    fpcr = 0x00000000
         = (AHP = 0, DN = 0, FZ = 0, RMMode = 0, FZ16 = 0, IDE = 0, IXE = 0, UFE = 0, OFE = 0, DZE = 0, IOE = 0)
```

Tests use the first 4 fields that we know are always present.

Converted all the HCWAP defines to `UL` because I'm bound to
forget one if I don't do it now.
@DavidSpickett DavidSpickett merged commit e3d750c into llvm:main Nov 9, 2023
@DavidSpickett DavidSpickett deleted the lldb-fpcr branch November 9, 2023 09:32
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
Projects
None yet
Development

Successfully merging this pull request may close these issues.

4 participants