Add ThreadContext, RegisterGroup, svcGetThreadContext3, threadDumpContext

nx/include/switch/arm/thread_context.h

@@ -0,0 +1,61 @@
+/**
+ * @file thread_context.h
+ * @brief AArch64 register dump format and related definitions.
+ * @author TuxSH
+ * @copyright libnx Authors
+ */
+
+#pragma once
+#include "../types.h"
+
+/// Armv8 CPU register.
+typedef union {
+    u64 x; ///< 64-bit AArch64 register view.
+    u32 w; ///< 32-bit AArch64 register view.
+    u32 r; ///< AArch32 register view.
+} CpuRegister;
+
+/// Armv8 NEON register.
+typedef union {
+    u128    v; ///< 128-bit vector view.
+    double  d; ///< 64-bit double-precision view.
+    float   s; ///< 32-bit single-precision view.
+} FpuRegister;
+
+/// Armv8 register group. @ref svcGetThreadContext3 uses @ref RegisterGroup_All.
+typedef enum {
+    RegisterGroup_CpuGprs = BIT(0), ///< General-purpose CPU registers (x0..x28 or r0..r10,r12).
+    RegisterGroup_CpuSprs = BIT(1), ///< Special-purpose CPU registers (fp, lr, sp, pc, PSTATE or cpsr, TPIDR_EL0).
+    RegisterGroup_FpuGprs = BIT(2), ///< General-purpose NEON registers.
+    RegisterGroup_FpuSprs = BIT(3), ///< Special-purpose NEON registers.
+
+    RegisterGroup_CpuAll  = RegisterGroup_CpuGprs | RegisterGroup_CpuSprs, ///< All CPU registers.
+    RegisterGroup_FpuAll  = RegisterGroup_FpuGprs | RegisterGroup_FpuSprs, ///< All NEON registers.
+    RegisterGroup_All     = RegisterGroup_CpuAll  | RegisterGroup_FpuAll,  ///< All registers.
+} RegisterGroup;
+
+/// Thread context structure (register dump)
+typedef struct {
+    CpuRegister cpu_gprs[29];   ///< GPRs 0..28. Note: also contains AArch32 SPRs.
+    u64 fp;                     ///< Frame pointer (x29) (AArch64). For AArch32, check r11.
+    u64 lr;                     ///< Link register (x30) (AArch64). For AArch32, check r14.
+    u64 sp;                     ///< Stack pointer (AArch64). For AArch32, check r13.
+    CpuRegister pc;             ///< Program counter.
+    u32         psr;            ///< PSTATE or cpsr.
+
+    FpuRegister fpu_gprs[32];   ///< 32 general-purpose NEON registers.
+    u32         fpcr;           ///< Floating-point control register.
+    u32         fpsr;           ///< Floating-point status register.
+
+    u64         tpidr;          ///< EL0 Read/Write Software Thread ID Register.
+} ThreadContext;
+
+/**
+ * @brief Determines whether a thread context belong to an AArch64 process based on the PSR.
+ * @param[in] ctx Thread context to which PSTATE/cspr has been dumped to.
+ * @return true if and only if the thread context belongs to an AArch64 process.
+ */
+static inline bool threadContextIsAArch64(const ThreadContext *ctx)
+{
+    return (ctx->psr & 0x10) == 0;
+}

nx/include/switch/kernel/svc.h

@@ -5,6 +5,7 @@
  */
 #pragma once
 #include "../types.h"
+#include "../arm/thread_context.h"
 
 /// Pseudo handle for the current process.
 #define CUR_PROCESS_HANDLE 0xFFFF8001
@@ -575,6 +576,16 @@ Result svcGetResourceLimitCurrentValue(u64 *out, Handle reslimit_h, LimitableRes
  */
 Result svcSetThreadActivity(Handle thread, bool paused);
 
+/**
+ * @brief Dumps the registers of a thread paused by @ref svcSetThreadActivity (register groups: all).
+ * @param[out] ctx Output thread context (register dump).
+ * @param[in] thread Thread handle.
+ * @return Result code.
+ * @note Syscall number 0x33.
+ * @warning Official kernel will not dump x0..x18 if the thread is currently executing a system call, and prior to 6.0.0 doesn't dump TPIDR_EL0.
+ */
+Result svcGetThreadContext3(ThreadContext* ctx, Handle thread);
+
 ///@}
 
 ///@name Inter-process communication (IPC)

nx/include/switch/kernel/thread.h

@@ -6,6 +6,7 @@
  */
 #pragma once
 #include "../types.h"
+#include "../arm/thread_context.h"
 
 /// Thread information structure.
 typedef struct {
@@ -63,3 +64,12 @@ Result threadPause(Thread* t);
  * @return Result code.
  */
 Result threadResume(Thread* t);
+
+/**
+ * @brief Dumps the registers of a thread paused by @ref threadPause (register groups: all).
+ * @param[out] ctx Output thread context (register dump).
+ * @param t Thread information structure.
+ * @return Result code.
+ * @warning Official kernel will not dump x0..x18 if the thread is currently executing a system call, and prior to 6.0.0 doesn't dump TPIDR_EL0.
+ */
+Result threadDumpContext(ThreadContext* ctx, Thread* t);

nx/source/kernel/svc.s

@@ -274,6 +274,11 @@ SVC_BEGIN svcSetThreadActivity
 	ret
 SVC_END
 
+SVC_BEGIN svcGetThreadContext3
+	svc 0x33
+	ret
+SVC_END
+
 SVC_BEGIN svcCreateSession
 	stp x0, x1, [sp, #-16]!
 	svc 0x40