Fixup Code That Calls __darling_handle_svc

* If not already done, add code to save and restore `fp` & `lr`.
* Update code that wasn't changed to call `__darling_handle_svc`
* Rework changes made to the macros.

Author: CuriousTommy

gen/bsdsyscalls/SYS.h

@@ -475,20 +475,31 @@ pseudo:									;\
  * TBD
  */
 
+#ifdef DARLING
 #define DO_SYSCALL(num, cerror)                 \
 	mov   x16, #(num)                     %%\
-#ifdef DARLING                            %%\
+	PUSH_FRAME                            %%\
 	bl    __darling_handle_svc            %%\
-#else                                     %%\
+	POP_FRAME                             %%\
+	b.cc  2f                              %%\
+	ARM64_STACK_PROLOG                    %%\
+	PUSH_FRAME                            %%\
+	bl    _##cerror                       %%\
+	POP_FRAME                             %%\
+	ARM64_STACK_EPILOG                    %%\
+2:
+#else
+#define DO_SYSCALL(num, cerror)                 \
+	mov   x16, #(num)                     %%\
 	svc   #SWI_SYSCALL                    %%\
-#endif                                    %%\
 	b.cc  2f                              %%\
 	ARM64_STACK_PROLOG                    %%\
 	PUSH_FRAME                            %%\
 	bl    _##cerror                       %%\
 	POP_FRAME                             %%\
 	ARM64_STACK_EPILOG                    %%\
 2:
+#endif
 
 #define MI_GET_ADDRESS(reg,var)  \
    adrp	reg, var@page      %%\

gen/bsdsyscalls/___vfork.S

@@ -232,7 +232,9 @@ Ltry_set_vfork:
 	// ARM sets r1 to 1 here.  I don't see why.
 	mov		w16, #SYS_vfork		// Set syscall code
 #ifdef DARLING
+	PUSH_FRAME
 	bl		__darling_handle_svc
+	POP_FRAME
 #else
 	svc		#SWI_SYSCALL
 #endif

libsyscall/custom/SYS.h

@@ -475,20 +475,31 @@ pseudo:									;\
  * TBD
  */
 
+#ifdef DARLING
 #define DO_SYSCALL(num, cerror)                 \
 	mov   x16, #(num)                     %%\
-#ifdef DARLING                            %%\
+	PUSH_FRAME                            %%\
 	bl    __darling_handle_svc            %%\
-#else                                     %%\
+	POP_FRAME                             %%\
+	b.cc  2f                              %%\
+	ARM64_STACK_PROLOG                    %%\
+	PUSH_FRAME                            %%\
+	bl    _##cerror                       %%\
+	POP_FRAME                             %%\
+	ARM64_STACK_EPILOG                    %%\
+2:
+#else
+#define DO_SYSCALL(num, cerror)                 \
+	mov   x16, #(num)                     %%\
 	svc   #SWI_SYSCALL                    %%\
-#endif                                    %%\
 	b.cc  2f                              %%\
 	ARM64_STACK_PROLOG                    %%\
 	PUSH_FRAME                            %%\
 	bl    _##cerror                       %%\
 	POP_FRAME                             %%\
 	ARM64_STACK_EPILOG                    %%\
 2:
+#endif
 
 #define MI_GET_ADDRESS(reg,var)  \
    adrp	reg, var@page      %%\

libsyscall/custom/__fork.S

@@ -154,7 +154,11 @@ MI_ENTRY_POINT(___fork)
 	PUSH_FRAME
 	// ARM moves a 1 in to r1 here, but I can't see why.
 	mov		x16, #SYS_fork				// Syscall code
+#ifdef DARLING
+	bl		__darling_handle_svc
+#else
 	svc		#SWI_SYSCALL				// Trap to kernel
+#endif
 	b.cs	Lbotch						// Carry bit indicates failure
 	cbz		x1, Lparent					// x1 == 0 indicates that we are the parent
 

libsyscall/custom/__vfork.S

@@ -231,7 +231,13 @@ Ltry_set_vfork:
 
 	// ARM sets r1 to 1 here.  I don't see why.
 	mov		w16, #SYS_vfork		// Set syscall code
+#ifdef DARLING
+	PUSH_FRAME
+	bl		__darling_handle_svc
+	POP_FRAME
+#else
 	svc		#SWI_SYSCALL
+#endif
 	b.cs 	Lbotch
 	cbz		w1, Lparent
 

libsyscall/custom/custom.S

@@ -137,14 +137,22 @@ __thread_set_tsd_base:
 	.align 2
 	.globl __thread_set_tsd_base
 __thread_set_tsd_base:
+#ifdef DARLING
+	stp fp, lr, [sp, #-16]!
+	mov fp, sp
+
 	mov	x3, #2
 	mov	x16, #0x80000000
-#ifdef DARLING
 	bl	__darling_handle_svc
+
+	ldp fp, lr, [sp], #16
+	ret
 #else
+	mov	x3, #2
+	mov	x16, #0x80000000
 	svc 	#SWI_SYSCALL
-#endif
 	ret
+#endif
 
 #else
 #error unknown architecture

osfmk/mach/arm/syscall_sw.h

@@ -106,19 +106,32 @@
 #elif defined(__arm64__)
 
 #include <mach/machine/vm_param.h>
+#ifdef DARLING
+// For PUSH_FRAME & POP_FRAME
+#include <mach/arm64/asm.h>
+#endif
 
+#ifdef DARLING
+#define kernel_trap(trap_name, trap_number, num_args) \
+.globl _##trap_name                                           %% \
+.text                                                         %% \
+.align  2                                                     %% \
+_##trap_name:                                                 %% \
+	PUSH_FRAME                                                %% \
+    mov x16, #(trap_number)                                   %% \
+    bl	__darling_handle_svc                                  %% \
+	POP_FRAME                                                 %% \
+	ret
+#else
 #define kernel_trap(trap_name, trap_number, num_args) \
 .globl _##trap_name                                           %% \
 .text                                                         %% \
 .align  2                                                     %% \
 _##trap_name:                                                 %% \
     mov x16, #(trap_number)                                   %% \
-#ifdef DARLING                                                %% \
-	bl	__darling_handle_svc                                   %% \
-#else                                                         %% \
     svc #SWI_SYSCALL                                          %% \
+	ret
 #endif
-    ret
 
 #else
 #error Unsupported architecture