Freescale Semiconductor PowerPC e500 Core - Data Storage Interrupt

Interrupts and Exceptions
PowerPC e500 Core Family Reference Manual, Rev. 1
Freescale Semiconductor 5-19
5.7.3 Data Storage Interrupt
A data storage interrupt (DSI) occurs when no higher priority exception exists and a data storage
exception is presented to the interrupt mechanism. Table 5-11 describes exception conditions for
a data storage interrupt as defined by Book E.
icbt, dcbt, dcbtst, and dcba instructions cannot cause a data storage interrupt, regardless of the
effective address.
Table 5-11. Data Storage Interrupt Exception Conditions
Exception Cause
Read access
control
exception
Occurs when either of the following conditions exists:
• In user mode (MSR[PR] = 1), a load or load-class cache management instruction attempts to access a
memory location that is not user-mode read enabled (page access control bit UR = 0).
• In supervisor mode (MSR[PR] = 0), a load or load-class cache management instruction attempts to access
a location that is not supervisor-mode read enabled (page access control bit SR = 0).
Write access
control
exception
Occurs when either of the following conditions exists:
• In user mode (MSR[PR] = 1), a store or store-class cache management instruction attempts to access a
location that is not user-mode write enabled (page access control bit UW = 0).
• In supervisor mode (MSR[PR] = 0), a store or store-class cache management instruction attempts to access
a location that is not supervisor-mode write enabled (page access control bit SW = 0).
Byte-ordering
exception
The implementation cannot access data in the byte order specified by the page’s endian attribute.
Note: The byte-ordering exception is provided to assist implementations that cannot support dynamically
switching byte ordering between consecutive accesses, the byte order for a class of accesses, or misaligned
accesses using a specific byte order.
On the e500, load/store accesses that cross a page boundary such that endianness changes cause a
byte-ordering exception.
Cache locking
exception
(EIS) The locked state of one or more cache lines has the potential to be altered. This exception is
implementation-dependent. A cache locking exception occurs with the execution of icbtls, icblc, dcbtls,
dcbtstls, or dcblc when (MSR[PR] = 1) and (MSR[UCLE] = 0). ESR is set as follows:
•For icbtls and icblc, ESR[ILK] is set.
•For dcbtls, dcbtstls, or dcblc, ESR[DLK] is set. Book E refers to this as a cache-locking exception.
Storage
synchronization
exception
Occurs when either of the following conditions exists:
• An attempt is made to execute a load and reserve or store conditional instruction from or to a location that
is write-through required or caching inhibited. (If the interrupt does not occur, the instruction executes
correctly.)
• A store conditional instruction produces an effective address for which a normal store would cause a data
storage interrupt but the processor does not have the reservation from a load and reserve instruction. Book E
states that it is implementation-dependent whether a data storage interrupt occurs. The EIS defines that the
data storage interrupt is taken.
See the section, “Atomic Update Primitives Using lwarx and stwcx.,” in the “Instruction Model” chapter of the
EREF.