Module openj9.dtfj

Package com.ibm.j9ddr.vm29.pointer.helper

Class J9MemTagHelper

java.lang.Object

com.ibm.j9ddr.vm29.pointer.helper.J9MemTagHelper

public class J9MemTagHelper
extends Object

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	J9MemTagHelper.J9MemTagCheckError

Field Summary

Fields

Modifier and Type	Field	Description
static IDATA	J9PORT_MEMTAG_FOOTER_PADDING_CORRUPTED
static IDATA	J9PORT_MEMTAG_FOOTER_TAG_CORRUPTED
static IDATA	J9PORT_MEMTAG_HEADER_TAG_CORRUPTED
static IDATA	J9PORT_MEMTAG_NOT_A_TAG
static IDATA	J9PORT_MEMTAG_VALID_TAG
static final long	ROUNDING_GRANULARITY

Constructor Summary

Constructors

Constructor	Description
J9MemTagHelper()

Method Summary

Modifier and Type	Method	Description
static void	checkPadding(com.ibm.j9ddr.vm29.pointer.generated.J9MemTagPointer headerTagAddress)	Checks that the padding associated with the memory block has not been corrupted
static void	checkTagSumCheck(com.ibm.j9ddr.vm29.pointer.generated.J9MemTagPointer tag, long eyeCatcher)	Checks that the memory tag is not corrupt.
static IDATA	j9mem_check_tags(VoidPointer memoryPointer, long headerEyecatcher, long footerEyecatcher)	Performs validation checks on the memory block starting at memoryPointer.
static VoidPointer	j9mem_get_footer_padding(com.ibm.j9ddr.vm29.pointer.generated.J9MemTagPointer headerEyeCatcherAddress)	Given the address of the headerEyecatcher for the memory block, return the address of the footer padding.
static com.ibm.j9ddr.vm29.pointer.generated.J9MemTagPointer	j9mem_get_footer_tag(com.ibm.j9ddr.vm29.pointer.generated.J9MemTagPointer headerEyeCatcherAddress)	Given the address of the headerEyecatcher for the memory block, return the address of the corresponding footer tag.
static com.ibm.j9ddr.vm29.pointer.generated.J9MemTagPointer	j9mem_get_header_tag(VoidPointer memoryPointer)	Given the address returned by @ref j9mem_allocate_memory(), return address of the header tag for the memory block
static VoidPointer	j9mem_get_memory_base(com.ibm.j9ddr.vm29.pointer.generated.J9MemTagPointer headerEyeCatcherAddress)	Given the address of the headerEyecatcher for the memory block, return the memory pointer that was returned by j9mem_allocate_memory() when the block was allocated.
static UDATA	ROUNDED_FOOTER_OFFSET(UDATA number)

Methods declared in class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

ROUNDING_GRANULARITY

public static final long ROUNDING_GRANULARITY

See Also:

• Constant Field Values

J9PORT_MEMTAG_HEADER_TAG_CORRUPTED

public static IDATA J9PORT_MEMTAG_HEADER_TAG_CORRUPTED

J9PORT_MEMTAG_FOOTER_TAG_CORRUPTED

public static IDATA J9PORT_MEMTAG_FOOTER_TAG_CORRUPTED

J9PORT_MEMTAG_FOOTER_PADDING_CORRUPTED

public static IDATA J9PORT_MEMTAG_FOOTER_PADDING_CORRUPTED

J9PORT_MEMTAG_NOT_A_TAG

public static IDATA J9PORT_MEMTAG_NOT_A_TAG

J9PORT_MEMTAG_VALID_TAG

public static IDATA J9PORT_MEMTAG_VALID_TAG

Constructor Details

J9MemTagHelper

public J9MemTagHelper()

Method Details

j9mem_check_tags

public static IDATA j9mem_check_tags(VoidPointer memoryPointer,
 long headerEyecatcher,
 long footerEyecatcher)
                              throws J9MemTagHelper.J9MemTagCheckError

Performs validation checks on the memory block starting at memoryPointer. The memory passed in could fall into one of three categories: 1) It could be a valid J9MemTag region with valid headers and footers 2) It could be not be a J9MemTag region 3) It could be a J9MemTag region with some corruption in either the header, footer or padding

Returns:

J9PORT_MEMTAG_NOT_A_TAG if memoryPointer address is not a tag J9PORT_MEMTAG_HEADER_TAG_CORRUPTED if memoryPointer address is valid tag region but header tag is corrupted. J9PORT_MEMTAG_FOOTER_TAG_CORRUPTED if memoryPointer address is valid tag region but footer tag is corrupted. J9PORT_MEMTAG_FOOTER_PADDING_CORRUPTED if memoryPointer address is valid tag region but footer padding is corrupted. J9PORT_MEMTAG_VALID_TAG if memoryPointer address is valid tag and header/footer are not corrupted.

Throws:

CorruptDataException - if the tags are corrupted, or the memory is inaccessible. (Option 3)

J9MemTagHelper.J9MemTagCheckError

checkTagSumCheck

public static void checkTagSumCheck(com.ibm.j9ddr.vm29.pointer.generated.J9MemTagPointer tag,
 long eyeCatcher)
                             throws CorruptDataException

Checks that the memory tag is not corrupt.

Throws:

CorruptDataException

j9mem_get_memory_base

public static VoidPointer j9mem_get_memory_base(com.ibm.j9ddr.vm29.pointer.generated.J9MemTagPointer headerEyeCatcherAddress)

Given the address of the headerEyecatcher for the memory block, return the memory pointer that was returned by j9mem_allocate_memory() when the block was allocated.

j9mem_get_footer_tag

public static com.ibm.j9ddr.vm29.pointer.generated.J9MemTagPointer j9mem_get_footer_tag(com.ibm.j9ddr.vm29.pointer.generated.J9MemTagPointer headerEyeCatcherAddress)
                                                                                 throws CorruptDataException

Given the address of the headerEyecatcher for the memory block, return the address of the corresponding footer tag.

Throws:

CorruptDataException

j9mem_get_header_tag

public static com.ibm.j9ddr.vm29.pointer.generated.J9MemTagPointer j9mem_get_header_tag(VoidPointer memoryPointer)

Given the address returned by @ref j9mem_allocate_memory(), return address of the header tag for the memory block

checkPadding

public static void checkPadding(com.ibm.j9ddr.vm29.pointer.generated.J9MemTagPointer headerTagAddress)
                         throws CorruptDataException

Checks that the padding associated with the memory block has not been corrupted

Throws:

CorruptDataException

j9mem_get_footer_padding

public static VoidPointer j9mem_get_footer_padding(com.ibm.j9ddr.vm29.pointer.generated.J9MemTagPointer headerEyeCatcherAddress)
                                            throws CorruptDataException

Given the address of the headerEyecatcher for the memory block, return the address of the footer padding. Note that there not be any padding, in which case this returns the same as @ref j9mem_get_footer_tag(), the address of the footer tag.

Throws:

CorruptDataException

ROUNDED_FOOTER_OFFSET

public static UDATA ROUNDED_FOOTER_OFFSET(UDATA number)