[Bug tapsets/18649] New: int_arg() misbehaves on x86[_64] for 32-bit uprobe in binary having debuginfo

[mcermak at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=18649

            Bug ID: 18649
           Summary: int_arg() misbehaves on x86[_64] for 32-bit uprobe in
                    binary having debuginfo
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: tapsets
          Assignee: systemtap at sourceware dot org
          Reporter: mcermak at redhat dot com
  Target Milestone: ---

The int_arg() function doesn't work correctly on i[36]86 and x86_64 when
probing 32-bit userspace application having debuginfo compiled in. Let's have
following program:

=======
int                                                                             
testfc(int arg)                                                                 
{                                                                               
    return arg;                                                                 
}                                                                               

int                                                                             
main()                                                                          
{                                                                               
    testfc(32767);                                                              
    return 0;                                                                   
}
=======

and probe it using following stap command:

=======
stap -e 'probe process("a.out").function("testfc") {printf("%x\n",
int_arg(1))}' -c ./a.out
=======

Following example demonstrates int_arg() returning nonsense value when 32-bit
binary having debuginfo is being traced:

=======
 7.2 S x86_64 # cat test.c
int
testfc(int arg)
{
    return arg;
}

int
main()
{
    testfc(32767);
    return 0;
}


 7.2 S x86_64 # gcc test.c 
 7.2 S x86_64 # stap -e 'probe process("a.out").function("testfc")
{printf("%x\n", int_arg(1))}' -c ./a.out
7fff
 7.2 S x86_64 # gcc -g test.c 
 7.2 S x86_64 # stap -e 'probe process("a.out").function("testfc")
{printf("%x\n", int_arg(1))}' -c ./a.out
7fff
 7.2 S x86_64 # gcc -m32 test.c 
 7.2 S x86_64 # stap -e 'probe process("a.out").function("testfc")
{printf("%x\n", int_arg(1))}' -c ./a.out
7fff
 7.2 S x86_64 # gcc -g -m32 test.c 
 7.2 S x86_64 # stap -e 'probe process("a.out").function("testfc")
{printf("%x\n", int_arg(1))}' -c ./a.out
804840a
 7.2 S x86_64 # 
=======

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