SyscallReturn Class Reference

This class represents the return value from an emulated system call, including any errno setting. More...

#include <syscall_return.hh>

Public Member Functions
	SyscallReturn (int64_t v)
	For simplicity, allow the object to be initialized with a single signed integer using the same positive=success, negative=-errno convention described above. More...
	~SyscallReturn ()
bool	successful () const
	Was the system call successful? More...
bool	needsRetry () const
	Does the syscall need to be retried? More...
int64_t	returnValue () const
	The return value. More...
int	errnoValue () const
	The errno value. More...
int64_t	encodedValue () const
	The encoded value (as described above) More...

Static Public Member Functions
static SyscallReturn	retry ()
	Pseudo-constructor to create an instance with the retry flag set. More...

Private Attributes
int64_t	value
bool	retryFlag

Detailed Description

This class represents the return value from an emulated system call, including any errno setting.

On some platforms, the return value and errno are encoded in a single signed integer. A value less than zero but greater than -4096 indicates an error, and the value is the negation of the errno value. Otherwise, the call was successful and the integer is the return value. (Large negative numbers are considered successful to allow syscalls to return pointers to high memory, e.g., stack addresses.) See, for example, Appendix A of the AMD64 ABI spec at http://www.x86-64.org/documentation/abi.pdf.

Other platforms use a more complex interface, returning a value and an error code in separate registers.

This class is designed to support both types of interfaces.

Definition at line 54 of file syscall_return.hh.

Constructor & Destructor Documentation

SyscallReturn::SyscallReturn ( int64_t  v )

inline

For simplicity, allow the object to be initialized with a single signed integer using the same positive=success, negative=-errno convention described above.

Typically this constructor is used as a default type conversion, so a bare integer is used where a SyscallReturn value is expected, e.g., as the return value from a system call emulation function ('return 0;' or 'return -EFAULT;').

Definition at line 66 of file syscall_return.hh.

SyscallReturn::~SyscallReturn ( )

inline

Definition at line 78 of file syscall_return.hh.

Member Function Documentation

int64_t SyscallReturn::encodedValue ( ) const

inline

The encoded value (as described above)

Definition at line 104 of file syscall_return.hh.

References value.

Referenced by SyscallDesc::doSyscall(), PowerProcess::setSyscallReturn(), ArmProcess32::setSyscallReturn(), X86ISA::X86Process::setSyscallReturn(), and ArmProcess64::setSyscallReturn().

int SyscallReturn::errnoValue ( ) const

inline

The errno value.

Definition at line 97 of file syscall_return.hh.

References successful(), and value.

Referenced by AlphaProcess::setSyscallReturn(), MipsProcess::setSyscallReturn(), RiscvProcess::setSyscallReturn(), and SparcProcess::setSyscallReturn().

bool SyscallReturn::needsRetry ( ) const

inline

Does the syscall need to be retried?

Definition at line 87 of file syscall_return.hh.

References retryFlag.

Referenced by SyscallDesc::doSyscall().

static SyscallReturn SyscallReturn::retry ( )

inlinestatic

Pseudo-constructor to create an instance with the retry flag set.

Definition at line 71 of file syscall_return.hh.

References retryFlag, and ArmISA::s.

int64_t SyscallReturn::returnValue ( ) const

inline

The return value.

Definition at line 90 of file syscall_return.hh.

References successful(), and value.

Referenced by AlphaProcess::setSyscallReturn(), MipsProcess::setSyscallReturn(), RiscvProcess::setSyscallReturn(), and SparcProcess::setSyscallReturn().

bool SyscallReturn::successful ( ) const

inline

Was the system call successful?

Definition at line 81 of file syscall_return.hh.

References value.

Referenced by errnoValue(), returnValue(), AlphaProcess::setSyscallReturn(), PowerProcess::setSyscallReturn(), MipsProcess::setSyscallReturn(), RiscvProcess::setSyscallReturn(), and SparcProcess::setSyscallReturn().

Member Data Documentation

bool SyscallReturn::retryFlag

private

Definition at line 113 of file syscall_return.hh.

Referenced by needsRetry(), and retry().

int64_t SyscallReturn::value

private

Definition at line 111 of file syscall_return.hh.

Referenced by encodedValue(), errnoValue(), returnValue(), and successful().

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The documentation for this class was generated from the following file:

• sim/syscall_return.hh