gensyscalls: alignment fixup for ARM

ARM ABI has different alignment requirements based on parameter size:
* parameters not larger than 4 bytes are aligned on 4 bytes
* parameters larger than 4 bytes are aligned on 8 bytes

see:
Procedure Call Standard for the Arm Architecture
sections 5.1, Fundamental Data Types
and 6.5, Parameter Passing

Therefore the following changes are introduced in gensyscalls tool:
* new optional define SYSCALL_LONG_PARAMETER_ALIGNMENT_TYPE is introduced
* it's defined only on ARM
* on other architectures it takes on the value of SYSCALL_PARAMETER_ALIGNMENT_TYPE as a default
* constants kLongParameterAlignmentType and kLongParameterAlignmentSize are introduced
* Syscall::AddParameter uses this value for aligning parameters larger than 4 bytes

Change-Id: I7e766e0ea9d07001643e813722b462b1f044921a
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5112
Reviewed-by: Adrien Destugues <[email protected]>
Tested-by: Commit checker robot <[email protected]>

src/tools/gensyscalls/arch/arm/arch_gensyscalls.h

@@ -1,2 +1,3 @@
-#define SYSCALL_RETURN_TYPE_ALIGNMENT_TYPE	int
-#define SYSCALL_PARAMETER_ALIGNMENT_TYPE	int
+#define SYSCALL_RETURN_TYPE_ALIGNMENT_TYPE		int
+#define SYSCALL_PARAMETER_ALIGNMENT_TYPE		int
+#define SYSCALL_LONG_PARAMETER_ALIGNMENT_TYPE	long long

src/tools/gensyscalls/gensyscallinfos.cpp

@@ -18,6 +18,10 @@
 #include "arch_gensyscalls.h"
 	// for the alignment type macros (only for the type names)
 
+#ifndef SYSCALL_LONG_PARAMETER_ALIGNMENT_TYPE
+#define SYSCALL_LONG_PARAMETER_ALIGNMENT_TYPE SYSCALL_PARAMETER_ALIGNMENT_TYPE
+#endif
+
 
 // macro trickery to create a string literal
 #define MAKE_STRING(x)	#x
@@ -357,10 +361,15 @@ private:
 		file << "const char* const kParameterAlignmentType = \""
 			EVAL_MACRO(MAKE_STRING, SYSCALL_PARAMETER_ALIGNMENT_TYPE)
 			<< "\";" << endl;
+		file << "const char* const kLongParameterAlignmentType = \""
+			EVAL_MACRO(MAKE_STRING, SYSCALL_LONG_PARAMETER_ALIGNMENT_TYPE)
+			<< "\";" << endl;
 		file << "const int kReturnTypeAlignmentSize = "
 			"SYSCALL_RETURN_TYPE_ALIGNMENT_SIZE;" << endl;
 		file << "const int kParameterAlignmentSize = "
 			"SYSCALL_PARAMETER_ALIGNMENT_SIZE;" << endl;
+		file << "const int kLongParameterAlignmentSize = "
+			"SYSCALL_LONG_PARAMETER_ALIGNMENT_SIZE;" << endl;
 		file << endl;
 
 		file << "SyscallVector* create_syscall_vector() {" << endl;
@@ -418,12 +427,18 @@ private:
 		file << endl;
 		file << "#include \"arch_gensyscalls.h\"" << endl;
 		file << endl;
+		file << "#ifndef SYSCALL_LONG_PARAMETER_ALIGNMENT_TYPE" << endl;
+		file << "#define SYSCALL_LONG_PARAMETER_ALIGNMENT_TYPE SYSCALL_PARAMETER_ALIGNMENT_TYPE"
+			<< endl;
+		file << "#endif" << endl;
 		file << "void dummy() {" << endl;
 
 		file << "DEFINE_COMPUTED_ASM_MACRO(SYSCALL_RETURN_TYPE_ALIGNMENT_SIZE, "
 			"sizeof(SYSCALL_RETURN_TYPE_ALIGNMENT_TYPE));" << endl;
   		file << "DEFINE_COMPUTED_ASM_MACRO(SYSCALL_PARAMETER_ALIGNMENT_SIZE, "
 			"sizeof(SYSCALL_PARAMETER_ALIGNMENT_TYPE));" << endl;
+		file << "DEFINE_COMPUTED_ASM_MACRO(SYSCALL_LONG_PARAMETER_ALIGNMENT_SIZE, "
+			"sizeof(SYSCALL_LONG_PARAMETER_ALIGNMENT_TYPE));" << endl;
 		file << endl;
 
 		// syscalls

src/tools/gensyscalls/gensyscalls.cpp

@@ -166,6 +166,15 @@ Syscall::AddParameter(int size, const char* typeName, const char* parameterName)
 	if (Parameter* previous = LastParameter())
 		offset = previous->Offset() + previous->UsedSize();
 
+	// take care of extra alignment for long parameters
+	// this is needed to sort out parameter offsets on ARM
+	if (size >= kLongParameterAlignmentSize) {
+		if ((offset % kLongParameterAlignmentSize) != 0) {
+			offset += kLongParameterAlignmentSize
+				- offset % kLongParameterAlignmentSize;
+		}
+	}
+
 	int usedSize = (size + kParameterAlignmentSize - 1)
 		/ kParameterAlignmentSize * kParameterAlignmentSize;
 	const char* alignmentType

src/tools/gensyscalls/gensyscalls.h

@@ -8,8 +8,10 @@
 
 extern const char* const kReturnTypeAlignmentType;
 extern const char* const kParameterAlignmentType;
+extern const char* const kLongParameterAlignmentType;
 extern const int kReturnTypeAlignmentSize;
 extern const int kParameterAlignmentSize;
+extern const int kLongParameterAlignmentSize;
 
 
 // Type