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atom_application_instrumentation(5)
NAME
atom_application_instrumentation, AddCallProto, AddCallProgram, AddCallObj,
AddCallProc, AddCallEntry, AddCallBlock, AddCallInst, ReplaceProto,
ReplaceEntry, ReplaceProcedure - Allows an Atom tool's instrumentation
routine to add, within an application program, calls to analysis routines
SYNOPSIS
#include <cmplrs/atom.inst.h>
void AddCallProto(
const char * );
void AddCallProgram(
PlaceType,
const char *, ... );
void AddCallObj(
Obj *,
PlaceType,
const char *, ... );
void AddCallProc(
Proc *,
PlaceType,
const char *, ... );
void AddCallEntry(
Entry *,
PlaceType,
const char *, ... );
void AddCallBlock(
Block *,
PlaceType,
const char *, ... );
void AddCallInst(
Inst *,
PlaceType,
const char *, ... );
void ReplaceProto(
const char * );
void ReplaceEntry(
Entry *,
const char *, ... );
void ReplaceProcedure(
Proc *,
const char * );
DESCRIPTION
The Atom application instrumentation routines allow you to add arbitrary
procedure calls before and after objects, procedures, basic blocks, and
instructions. You can also add procedure calls before a main or alternate
entry point. In addition, you can add procedure calls before and after the
application program executes.
You can use these routines only from an Atom tool's instrumentation file.
See atom(1) for a description of Atom.
AddCallProto Routine
You must use the AddCallProto routine to specify the prototype of each
procedure call to be added to the program. In other words, an AddCallProto
call must define the procedural interface for each call to an analysis
procedure to be added to the program by subsequent calls to AddCallProgram,
AddCallObj, AddCallProc, AddCallEntry, AddCallBlock, and AddCallInst.
The format of the prototype is similar to a C language function definition.
The name of the analysis procedure is followed by a parenthesized list of
arguments.
There are four basic argument types:
· Constants
· Computed values (VALUE)
· Register values (REGV and FREGV)
· Address translation structure (*XLATE)
Constant types include char, int, long, char *, char[], int[], and long[].
Often, arrays are used to communicate static information, especially large
data structures, to analysis procedures. Three special keywords exist to
facilitate the passing of array and string arguments:
const
Indicates that the analysis routine cannot modify or write to the
passed array or string. Atom allocates the memory for such a string or
array in the instrumented program's read-only memory. Using const can
thus greatly reduce the memory usage of instrumented programs that have
multiple images active simultaneously.
stable
Indicates that Atom does not need to make a copy of the data for the
string or array during instrumentation. If your instrumentation code
passes a stable buffer to AddCallObj, AddCallProc, AddCallEntry,
AddCallBlock, or AddCallInst, it must not modify or free the buffer
until after WriteObj is called for the object containing the given Obj,
Proc, Entry, Block, or Inst. If you pass a stable buffer to
AddCallProgram, you must never modify or free the buffer.
Strings returned by the following routines can be considered stable for
the duration of the instrumentation process: GetObjName, GetObjOutName,
GetAnalName, GetObjInstArray, ProcName, ProcFileName, and
GetInstProcCalled.
free
Indicates that Atom does not need to make a copy of the data for the
string or array during instrumentation and that it will deallocate the
buffer (by calling free) when it is done with it. Instrumentation code
should never modify or free such a buffer after it has been passed to
AddCallObj, AddCallProc, AddCallEntry, AddCallBlock, AddCallInst, or
AddCallProgram.
You can use the const keyword with either stable or free. The stable and
free keywords are mutually exclusive.
The VALUE argument type defines an argument with a 64-bit value that Atom
must compute before passing it to the analysis procedure. There are two
arguments of the VALUE argument type, as listed in the following table. For
such arguments, specify VALUE in the AddCallProto call and the argument's
symbolic name in the call to AddCallObj, AddCallProc, AddCallEntry,
AddCallBlock, AddCallInst, or AddCallProgram.
____________________________________________________________________
Type Argument Description
____________________________________________________________________
VALUE EffAddrValue
Effective load-time address of a load or
store instruction. This is the sum of the
64-bit address contained in the base register
and the signed 16-bit displacement. (Note
that, for a shared library, the run-time PC
differs from the compile-time PC.) This
argument is valid only on load or store
instructions instrumented by an AddCallInst
call with InstBefore specified. Otherwise,
Atom reports an error.
VALUE BrCondValue
Outcome of a conditional branch instruction.
Returns a zero (0) if the branch condition
will evaluate to false or a 64-bit nonzero
value if it will evaluate to true. This
argument is valid only on conditional branch
instructions instrumented by an AddCallInst
call with InstBefore specified. Otherwise,
Atom reports an error.
____________________________________________________________________
The REGV and FREGV argument types define an argument representing the
contents of a register. FREGV is used for floating-point registers; REGV
is used for all other registers. There are several arguments of the REGV
and FREGV argument types, as listed in the following table. For such
arguments, specify REGV or FREGV in the AddCallProto call and the
argument's symbolic name in the call to AddCallObj, AddCallProc,
AddCallEntry, AddCallBlock, AddCallInst, or AddCallProgram.
___________________________________________________________________
Type Argument Description
___________________________________________________________________
REGV REG_n
Integer register n, where n is a value from 0
to 31.
REGV REG_RA Return address register.
REGV REG_GP Global pointer.
REGV REG_SP Stack pointer.
REGV REG_ZERO Integer register 31.
REGV REG_CC Processor cycle counter.
REGV REG_PC
Pure compile-time (that is, noninstrumented)
program counter at the instrumentation point.
(Note that, for a shared library, the run-
time PC differs from the compile-time PC.)
REGV REG_IPC
Instrumented program counter at run-time If
the call is from a shared library, the run-
time PC is passed.
REGV REG_ARG_n
Integer argument register n, where n is a
value from 1 to 6.
REGV REG_RETVAL Integer function return value.
REGV FREG_n
Floating-point register n, where n is a value
from 0 to 31.
FREGV FREG_ZERO Floating-point register 31.
FREGV FREG_ARG_n
Floating-point argument register n, where n
is a value from 1 to 6.
FREGV FREG_RETVAL Floating-point function return value.
___________________________________________________________________
Note that the special REGV-type value REG_NOTUSED is also defined as a
return value from GetInstRegEnum. You cannot pass it as an argument to
AddCallObj, AddCallProc, AddCallEntry, AddCallBlock, AddCallInst, or
AddCallProgram.
Note
When you use AddCallObj, you will sometimes find that the analysis
routine for each added call requires a slightly different prototype.
This usually occurs when you pass an array argument and the number of
elements in the array depends on the contents of the object. Normally,
it is illegal to reprototype an analysis routine, but Atom makes an
exception for array parameters. If the only difference between the new
prototype and the old prototype is the length of an array parameter,
Atom allows you to use AddCallProto to reprototype the analysis
routine. Subsequent calls to that analysis routine will use the new
array length.
AddCallProgram Routine
Use the AddCallProgram routine in an InstrumentInit or InstrumentAll
routine to add a call to an analysis procedure before a program starts
execution or after it completes execution. Typically such an analysis
procedure does something that applies to the whole program, such as opening
an output file or parsing command line options. Supply a PlaceType value of
ProgramBefore or ProgramAfter as the instrumentation point, followed by the
name of the analysis procedure and a list of its arguments. Since
ProgramAfter actions are executed after the program is complete, library
routines requiring system services should not be used in ProgramAfter
analysis routines.
Because the Instrument routine is called for each object in a program,
avoid calling AddCallProgram from the Instrument routine.
If the program forks and ProgramBefore is specified, Atom calls the
analysis procedure only once - before the parent process starts execution.
If ProgramAfter is specified, Atom calls the analysis procedure after each
child process completes execution and after the parent process completes
execution.
AddCallObj Routine
Use the AddCallObj routine in an instrumentation routine to add a call to
an analysis procedure before an object starts execution or after it
completes execution. Typically such an analysis procedure does something
that applies to the single object, such as initializing some data for its
procedures. Supply a PlaceType value of ObjBefore or ObjAfter as the
instrumentation point, followed by the name of the analysis procedure and a
list of its arguments.
Instrumentation code added at the beginning of an object is executed
immediately after the object is loaded into memory (before any procedures
in that object are executed). Instrumentation code added at the end of an
object is executed immediately before that object is unloaded from memory
(after all procedures from that object have finished execution).
Note
An InstrumentAll routine must call the BuildObj routine before calling
AddCallObj, AddCallProc, AddCallEntry, AddCallBlock, or AddCallInst to
add analysis routine calls, and before traversing the procedures in
the object. BuildObj builds the internal data structures Atom uses to
manipulate the object. After the Atom tool traverses and instruments
the object, the InstrumentAll routine must call the WriteObj routine
to write out the instrumented version of the object. See the
atom_object_management(5) reference page for additional information.
AddCallProc Routine
Use the AddCallProc routine in an instrumentation routine to add a call to
an analysis procedure before a procedure starts execution or after it
completes execution. Supply a PlaceType value of ProcBefore or ProcAfter as
the instrumentation point, followed by the name of the analysis procedure
and a list of its arguments. The following factors determine when the
analysis procedures are called:
· If the procedure has multiple entry points and ProcBefore is
specified, Atom calls the analysis procedure at each entry point.
· If the procedure has multiple exit points and ProcAfter is specified,
Atom calls the analysis procedure each time it issues a return. If the
procedure contains interprocedural branches or interprocedural jumps,
the call to the analysis procedure will occur before the branch or
jump. Compilers can optimize return statements or non-returning
function calls to interprocedural branches. To avoid this, recompile
with -O0 or -no_inline.
· If the procedure does not issue a return (for example, it calls exit
or longjmp), Atom does not call the analysis procedure.
AddCallEntry Routine
Use the AddCallEntry routine in an instrumentation routine to add a call to
an analysis routine before a main or alternate entry starts execution.
Supply a PlaceType value of EntryBefore as the instrumentation point,
followed by the name of the analysis procedure and a list of its arguments.
AddCallBlock Routine
Use the AddCallBlock routine in an instrumentation routine to add a call to
an analysis procedure before a basic block starts execution or after it
completes execution. Supply a PlaceType value of BlockBefore or BlockAfter
as the instrumentation point, followed by the name of the analysis
procedure and a list of its arguments.
If the basic block ends with an unconditional branch or jump and BlockAfter
is specified, Atom calls the analysis procedure after the basic block
completes execution. However, if the basic block ends with a jump to a
subroutine that does not return (for instance, the subroutine calls exit or
longjmp), Atom does not call the analysis procedure.
AddCallInst Routine
Use the AddCallInst routine in an instrumentation routine to add a call to
an analysis procedure before a given instruction executes or after it
executes. Supply a PlaceType value of InstBefore or InstAfter as the
instrumentation point, followed by the name of the analysis procedure and a
list of its arguments.
If the instruction is an unconditional branch or jump and InstAfter is
specified, Atom calls the analysis procedure after the instruction
executes. However, if the instruction is a jump to a subroutine that does
not return (for example, the subroutine calls exit or longjmp), Atom does
not call the analysis procedure.
PlaceType Hierarchy
An implied PlaceType hierarchy exists in the execution ordering of calls to
analysis procedures when the calls occur at the same instrumentation point.
By enforcing an ordering, Atom guarantees, for instance, that a call to an
analysis procedure added at BlockBefore executes before a call to an
analysis procedure added at InstBefore when the Inst and the Block identify
the same instrumentation point.
The before PlaceType ordering of calls is:
ProgramBefore
ObjBefore
ProcBefore or EntryBefore
BlockBefore
InstBefore
The after PlaceType ordering of calls is:
InstAfter
BlockAfter
ProcAfter
ObjAfter
ProgramAfter
Multiple calls added at the same instrumentation point via the same
PlaceType will be executed in the order they were instrumented. Multiple
calls added at the same instrumentation point via the ProcBefore and
EntryBefore PlaceTypes will also be executed in the order they were
instrumented since the ProcBefore and EntryBefore PlaceTypes have the same
before PlaceType ordering.
ReplaceEntry Routine
Use the ReplaceEntry routine to intercept an application's calls to a given
main or alternate entry point. Only calls that follow the Alpha Calling
Standard can be intercepted, and calls that have been expanded inline by
compiler optimizations cannot be intercepted.
The char * argument indicates the name of the replacement procedure in the
tool's analysis code that will be called instead of the replaced entry
point. Only the specified entry point is replaced; other entry points in
the same procedure may be replaced by using additional ReplaceEntry calls.
In addition to performing the desired analysis, the replacement procedure
should emulate the replaced entry point by accepting all the same arguments
and returning a comparable return value. Replacement procedures usually
implement this emulation by calling the replaced entry point through a
function pointer that is either passed into the replacement procedure as
the ReplAddrValue argument (see below) or is initialized by calling the
XlateAddr routine with an address translation buffer set up via the
AddXlateEntry routine.
Note that replacing entry points containing thread cancellation points is
not supported.
The tool's instrumentation code must call the ReplaceProto routine first,
in the same way that the AddCallProto routine must be called before the
AddCallProc routine. ReplaceProto must be called before the main
executable is written.
ReplaceProto Routine
You must use the ReplaceProto routine to declare the procedural interface
to any replacement procedure before making the associated ReplaceEntry
call. ReplaceProto's single string pointer argument has the same format as
that of AddCallProto. ReplaceProto accepts a superset of AddCallProto's
procedural interface arguments, to allow application and analysis data to
be passed into the replacement procedure.
The following two additional arguments can be used to provide the
replacement procedure with the application arguments and the address of the
replaced entry point. These arguments have VALUE argument types and are
similar to those supported by the AddCallProto routine. Note that currently
only fixed arguments are supported, not "..." variable argument lists.
_____________________________________________________________________
Type Argument Description
_____________________________________________________________________
VALUE ArgValue
A fixed argument of the replaced entry point.
For an entry point with N arguments, the
first N arguments in the ReplaceProto string,
the ReplaceEntry call (after the Entry
pointer and replacement name), and the
replacement routine's definition must match
the N arguments of the replaced entry point.
VALUE ReplAddrValue
The address of the replaced entry point in
the running instrumented application. This
address is equivalent to an Xlate address
generated by AddXlateEntry.
_____________________________________________________________________
For example, the following pair of ReplaceProto and ReplaceEntry calls
intercepts calloc(3) library calls, passing two application arguments and
three additional analysis arguments (the return address of the
application's call to calloc, the replaced library routine's run-time
address, and the ObjID of the object that contains calloc).
ReplaceProto("replacement_calloc(VALUE, VALUE, REGV, VALUE, long)");
ReplaceEntry(FindEntry(obj,"calloc"), "replacement_calloc",
ArgValue, ArgValue, REG_RA, ReplAddrValue,
GetObjInfo(obj,ObjID));
The associated replacement routine would be declared like this:
int replacement_calloc(size_t num, size_t size, long ra,
void *(*replaced_calloc)(size_t, size_t),
long obj_id);
ReplaceProcedure Routine
Use the ReplaceProcedure routine to replace a procedure with a routine that
has the same arguments and return type but is linked with your analysis
code. The named replacement code should emulate the replaced procedure, and
it will usually also analyze all the calls made to it by applications. Any
alternate entry points are also replaced and are assumed to have the same
arguments and return type.
The ReplaceProcedure routine does not support replacing undocumented
library routines, and it does not support replacement routines that are
optimized in certain ways. It is retained for compatibility with earlier
releases, but using ReplaceEntry (above) is recommended.
EXAMPLES
The following example accumulates wall-clock and per-process time for a
procedure. The instrumentation routine defines the prototypes for calls to
analysis procedures and identifies the instrumentation points at which
those calls take place:
AddCallProto("Start(REGV)");
AddCallProto("Stop(REGV)");
.
.
.
AddCallProc(p,ProcBefore,"Start",REG_CC);
AddCallProc(p,ProcAfter,"Stop",REG_CC);
.
.
.
The analysis routine is complicated by the format of the cycle counter. The
low-order 32 bits contain a free running cycle count. The high-order 32
bits of the counter are an offset that, when added to the low-order 32
bits, produces a cycle count for this process. The low-order 32 bits can be
used directly to determine wall clock times:
long total;
long process;
int ccStart;
int ccStartProcess;
void Start(unsigned long cc) {
ccStart = cc;
ccStartProcess = ((cc << 32) + cc) >> 32;
}
void Stop(unsigned long cc) {
int ccEnd = cc;
int ccEndProcess = ((cc << 32) + cc) >> 32;
total += (unsigned) (ccEnd - ccStart);
process += (unsigned) (ccEndProcess - ccStartProcess);
}
RETURN VALUES
These routines have no return values.
FILES
/usr/include/cmplrs/atom.inst.h
Header file containing external definitions of Atom routines
SEE ALSO
Commands: atom(1)
Functions: atom_application_navigation(5), atom_application_query(5),
atom_application_symbols(5), atom_description_file(5),
atom_instrumentation_routines(5), atom_object_management(5),
AnalHeapBase(5), Thread(5), Xlate(5)
Programmer's Guide
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