[cDAC] ARM Stackwalking (#116645)

* Add ARMContext, ARMFrameHandler, and ARMUnwinder
* ARM SoftwareExceptionFrames support
* ARM InlinedCallFrame support
* ARM TransitionFrame support
* ARM FaultingExceptionFrame support
* ARM HijackFrame support

Author: max-charlamb

docs/design/datacontracts/StackWalk.md

@@ -42,11 +42,13 @@ This contract depends on the following descriptors:
 | `InlinedCallFrame` | `CallSiteSP` | SP saved in Frame |
 | `InlinedCallFrame` | `CallerReturnAddress` | Return address saved in Frame |
 | `InlinedCallFrame` | `CalleeSavedFP` | FP saved in Frame |
+| `InlinedCallFrame` (arm) | `SPAfterProlog` | Value of the SP after prolog. Used on ARM to maintain additional JIT invariant |
 | `SoftwareExceptionFrame` | `TargetContext` | Context object saved in Frame |
 | `SoftwareExceptionFrame` | `ReturnAddress` | Return address saved in Frame |
 | `FramedMethodFrame` | `TransitionBlockPtr` | Pointer to Frame's TransitionBlock |
 | `TransitionBlock` | `ReturnAddress` | Return address associated with the TransitionBlock |
 | `TransitionBlock` | `CalleeSavedRegisters` | Platform specific CalleeSavedRegisters struct associated with the TransitionBlock |
+| `TransitionBlock` (arm) | `ArgumentRegisters` | ARM specific `ArgumentRegisters` struct |
 | `FuncEvalFrame` | `DebuggerEvalPtr` | Pointer to the Frame's DebuggerEval object |
 | `DebuggerEval` | `TargetContext` | Context saved inside DebuggerEval |
 | `DebuggerEval` | `EvalDuringException` | Flag used in processing FuncEvalFrame |
@@ -56,7 +58,8 @@ This contract depends on the following descriptors:
 | `HijackFrame` | `HijackArgsPtr` | Pointer to the Frame's stored HijackArgs |
 | `HijackArgs` (amd64) | `CalleeSavedRegisters` | CalleeSavedRegisters data structure |
 | `HijackArgs` (amd64 Windows) | `Rsp` | Saved stack pointer |
-| `HijackArgs` (arm64/x86) | For each register `r` saved in HijackArgs, `r` | Register names associated with stored register values |
+| `HijackArgs` (arm/arm64/x86) | For each register `r` saved in HijackArgs, `r` | Register names associated with stored register values |
+| `ArgumentRegisters` (arm) | For each register `r` saved in ArgumentRegisters, `r` | Register names associated with stored register values |
 | `CalleeSavedRegisters` | For each callee saved register `r`, `r` | Register names associated with stored register values |
 | `TailCallFrame` (x86 Windows) | `CalleeSavedRegisters` | CalleeSavedRegisters data structure |
 | `TailCallFrame` (x86 Windows) | `ReturnAddress` | Frame's stored instruction pointer |
@@ -244,6 +247,8 @@ Most of the handlers are implemented in `BaseFrameHandler`. Platform specific co
 
 InlinedCallFrames store and update only the IP, SP, and FP of a given context. If the stored IP (CallerReturnAddress) is 0 then the InlinedCallFrame does not have an active call and should not update the context.
 
+* On ARM, the InlinedCallFrame stores the value of the SP after the prolog (`SPAfterProlog`) to allow unwinding for functions with stackalloc. When a function uses stackalloc, the CallSiteSP can already have been adjusted. This value should be placed in R9.
+
 #### SoftwareExceptionFrame
 
 SoftwareExceptionFrames store a copy of the context struct. The IP, SP, and all ABI specified (platform specific) callee-saved registers are copied from the stored context to the working context.
@@ -254,6 +259,8 @@ TransitionFrames hold a pointer to a `TransitionBlock`. The TransitionBlock hold
 
 When updating the context from a TransitionFrame, the IP, SP, and all ABI specified callee-saved registers are copied over.
 
+* On ARM, the additional register values stored in `ArgumentRegisters` are copied over. The `TransitionBlock` holds a pointer to the `ArgumentRegister` struct containing these values.
+
 The following Frame types also use this mechanism:
 * FramedMethodFrame
 * CLRToCOMMethodFrame
@@ -289,7 +296,9 @@ HijackFrames carry a IP (ReturnAddress) and a pointer to `HijackArgs`. All platf
 * x64 - On x64, HijackArgs contains a CalleeSavedRegister struct. The saved registers values contained in the struct are copied over to the working context.
     * Windows - On Windows, HijackArgs also contains the SP value directly which is copied over to the working context.
     * Non-Windows - On OS's other than Windows, HijackArgs does not contain an SP value. Instead since the HijackArgs struct lives on the stack, the SP is `&hijackArgs + sizeof(HijackArgs)`. This value is also copied over.
-* arm64 - Unlike on x64, on arm64 HijackArgs contains a list of register values instead of the CalleeSavedRegister struct. These values are copied over to the working context. The SP is fetched using the same technique as on x64 non-Windows where `SP = &hijackArgs + sizeof(HijackArgs)` and is copied over to the working context.
+* x86 - On x86, HijackArgs contains a list of register values instead of the CalleeSavedRegister struct. These values are copied over to the working context. The SP copied over to the working context and found using `SP = &hijackArgs + sizeof(HijackArgs)`.
+* arm64 - Unlike on x64, on arm64 HijackArgs contains a list of register values instead of the CalleeSavedRegister struct. These values are copied over to the working context. The SP is fetched using the same technique as on x64 non-Windows where `SP = &hijackArgs + sizeof(HijackArgs) + (hijackArgsSize % 16)` and is copied over to the working context. Note: `HijackArgs` may be padded to maintain 16 byte stack alignment.
+* arm - Similar to arm64, HijackArgs contains a list of register values. These values are copied over to the working context. The SP is fetched using the same technique as arm64 where `SP = &hijackArgs + sizeof(HijackArgs) + (hijackArgsSize % 8)` and is copied over to the working context. Note: `HijackArgs` may be padded to maintain 8 byte stack alignment.
 
 #### TailCallFrame
 

src/coreclr/debug/runtimeinfo/datadescriptor.h

@@ -706,6 +706,9 @@ CDAC_TYPE_SIZE(sizeof(InlinedCallFrame))
 CDAC_TYPE_FIELD(InlinedCallFrame, /*pointer*/, CallSiteSP, offsetof(InlinedCallFrame, m_pCallSiteSP))
 CDAC_TYPE_FIELD(InlinedCallFrame, /*pointer*/, CallerReturnAddress, offsetof(InlinedCallFrame, m_pCallerReturnAddress))
 CDAC_TYPE_FIELD(InlinedCallFrame, /*pointer*/, CalleeSavedFP, offsetof(InlinedCallFrame, m_pCalleeSavedFP))
+#ifdef TARGET_ARM
+CDAC_TYPE_FIELD(InlinedCallFrame, /*pointer*/, SPAfterProlog, offsetof(InlinedCallFrame, m_pSPAfterProlog))
+#endif // TARGET_ARM
 CDAC_TYPE_END(InlinedCallFrame)
 
 CDAC_TYPE_BEGIN(SoftwareExceptionFrame)
@@ -723,6 +726,9 @@ CDAC_TYPE_BEGIN(TransitionBlock)
 CDAC_TYPE_SIZE(sizeof(TransitionBlock))
 CDAC_TYPE_FIELD(TransitionBlock, /*pointer*/, ReturnAddress, offsetof(TransitionBlock, m_ReturnAddress))
 CDAC_TYPE_FIELD(TransitionBlock, /*CalleeSavedRegisters*/, CalleeSavedRegisters, offsetof(TransitionBlock, m_calleeSavedRegisters))
+#ifdef TARGET_ARM
+CDAC_TYPE_FIELD(TransitionBlock, /*ArgumentRegisters*/, ArgumentRegisters, offsetof(TransitionBlock, m_argumentRegisters))
+#endif // TARGET_ARM
 CDAC_TYPE_END(TransitionBlock)
 
 #ifdef DEBUGGING_SUPPORTED
@@ -788,6 +794,19 @@ CDAC_TYPE_FIELD(HijackArgs, /*pointer*/, Eax, offsetof(HijackArgs, Eax))
 CDAC_TYPE_FIELD(HijackArgs, /*pointer*/, Ebp, offsetof(HijackArgs, Ebp))
 CDAC_TYPE_FIELD(HijackArgs, /*pointer*/, Eip, offsetof(HijackArgs, Eip))
 
+#elif defined(TARGET_ARM)
+
+CDAC_TYPE_FIELD(HijackArgs, /*pointer*/, R0, offsetof(HijackArgs, R0))
+CDAC_TYPE_FIELD(HijackArgs, /*pointer*/, R2, offsetof(HijackArgs, R2))
+CDAC_TYPE_FIELD(HijackArgs, /*pointer*/, R4, offsetof(HijackArgs, R4))
+CDAC_TYPE_FIELD(HijackArgs, /*pointer*/, R5, offsetof(HijackArgs, R5))
+CDAC_TYPE_FIELD(HijackArgs, /*pointer*/, R6, offsetof(HijackArgs, R6))
+CDAC_TYPE_FIELD(HijackArgs, /*pointer*/, R7, offsetof(HijackArgs, R7))
+CDAC_TYPE_FIELD(HijackArgs, /*pointer*/, R8, offsetof(HijackArgs, R8))
+CDAC_TYPE_FIELD(HijackArgs, /*pointer*/, R9, offsetof(HijackArgs, R9))
+CDAC_TYPE_FIELD(HijackArgs, /*pointer*/, R10, offsetof(HijackArgs, R10))
+CDAC_TYPE_FIELD(HijackArgs, /*pointer*/, R11, offsetof(HijackArgs, R11))
+
 #endif // Platform switch
 CDAC_TYPE_END(HijackArgs)
 #endif // FEATURE_HIJACK
@@ -807,6 +826,19 @@ CDAC_TYPE_FIELD(TailCallFrame, /*pointer*/, ReturnAddress, cdac_data<TailCallFra
 CDAC_TYPE_END(TailCallFrame)
 #endif // TARGET_X86 && !UNIX_X86_ABI
 
+// ArgumentRegisters struct is different on each platform
+CDAC_TYPE_BEGIN(ArgumentRegisters)
+CDAC_TYPE_SIZE(sizeof(ArgumentRegisters))
+#if defined(TARGET_ARM)
+
+CDAC_TYPE_FIELD(ArgumentRegisters, /*nuint*/, R0, offsetof(ArgumentRegisters, r[0]))
+CDAC_TYPE_FIELD(ArgumentRegisters, /*nuint*/, R1, offsetof(ArgumentRegisters, r[1]))
+CDAC_TYPE_FIELD(ArgumentRegisters, /*nuint*/, R2, offsetof(ArgumentRegisters, r[2]))
+CDAC_TYPE_FIELD(ArgumentRegisters, /*nuint*/, R3, offsetof(ArgumentRegisters, r[3]))
+
+#endif // TARGET_ARM
+CDAC_TYPE_END(ArgumentRegisters)
+
 // CalleeSavedRegisters struct is different on each platform
 CDAC_TYPE_BEGIN(CalleeSavedRegisters)
 CDAC_TYPE_SIZE(sizeof(CalleeSavedRegisters))
@@ -817,6 +849,18 @@ CDAC_TYPE_SIZE(sizeof(CalleeSavedRegisters))
 ENUM_CALLEE_SAVED_REGISTERS()
 #undef CALLEE_SAVED_REGISTER
 
+#elif defined(TARGET_ARM)
+
+CDAC_TYPE_FIELD(CalleeSavedRegisters, /*nuint*/, R4, offsetof(CalleeSavedRegisters, r4))
+CDAC_TYPE_FIELD(CalleeSavedRegisters, /*nuint*/, R5, offsetof(CalleeSavedRegisters, r5))
+CDAC_TYPE_FIELD(CalleeSavedRegisters, /*nuint*/, R6, offsetof(CalleeSavedRegisters, r6))
+CDAC_TYPE_FIELD(CalleeSavedRegisters, /*nuint*/, R7, offsetof(CalleeSavedRegisters, r7))
+CDAC_TYPE_FIELD(CalleeSavedRegisters, /*nuint*/, R8, offsetof(CalleeSavedRegisters, r8))
+CDAC_TYPE_FIELD(CalleeSavedRegisters, /*nuint*/, R9, offsetof(CalleeSavedRegisters, r9))
+CDAC_TYPE_FIELD(CalleeSavedRegisters, /*nuint*/, R10, offsetof(CalleeSavedRegisters, r10))
+CDAC_TYPE_FIELD(CalleeSavedRegisters, /*nuint*/, R11, offsetof(CalleeSavedRegisters, r11))
+CDAC_TYPE_FIELD(CalleeSavedRegisters, /*nuint*/, Lr, offsetof(CalleeSavedRegisters, r14))
+
 #elif defined(TARGET_ARM64)
 
 CDAC_TYPE_FIELD(CalleeSavedRegisters, /*nuint*/, X19, offsetof(CalleeSavedRegisters, x19))

src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/DataType.cs

@@ -103,6 +103,7 @@ public enum DataType
 
     TransitionBlock,
     DebuggerEval,
+    ArgumentRegisters,
     CalleeSavedRegisters,
     HijackArgs,