[Bug translator/12498] systemtap.examples/process/noptrace hangs on RHEL4 because arguments are wrong

["wcohen at redhat dot com" <sourceware-bugzilla at sourceware dot org>]

http://sourceware.org/bugzilla/show_bug.cgi?id=12498

--- Comment #2 from William Cohen <wcohen at redhat dot com> 2011-02-18 20:59:17 UTC ---
On RHEL5 puts the probe at the first instruction of sys_ptrace function. On the
i686 RHEL4 system the probe in put farther into the function. RHEL4:

[wcohen@slingshot obj]$ stap -p2 -e 'probe syscall.ptrace{printf("%s\n",
$$parms)}' -c 'strace ls'
# functions
_dwarf_tvar_get_addr_6:long ()
_dwarf_tvar_get_data_7:long ()
_dwarf_tvar_get_pid_5:long ()
_dwarf_tvar_get_request_4:long ()
# probes
kernel.function("sys_ptrace@arch/i386/kernel/ptrace.c:235").call? /*
pc=_stext+0x985c */ /* <- syscall.ptrace = kernel.function("sys_ptrace").call?
<- syscall.ptrace */

using the _stext from System.Map-`uname -r`
pc=_stext+0x985c = c0100298  + 0x985c = C0109AF4

c0109af2 <sys_ptrace>:
c0109af2:    55                       push   %ebp
c0109af3:    57                       push   %edi
c0109af4:    bf 00 f0 ff ff           mov    $0xfffff000,%edi #<-probe here
c0109af9:    56                       push   %esi
c0109afa:    53                       push   %ebx
c0109afb:    53                       push   %ebx
c0109afc:    53                       push   %ebx
c0109afd:    8b 5c 24 24              mov    0x24(%esp),%ebx
c0109b01:    21 e7                    and    %esp,%edi


Due to the eu-readelf being really old on RHEL-4, I copied the vmlinux over to
RHEL-5 and did the following:

eu-readelf --debug-dump=info  vmlinux > /tmp/debug

section of interest:

[ 862dd]    subprogram
             sibling              [ 86b9f]
             external             
             name                 "sys_ptrace"
             decl_file            1
             decl_line            235
             prototyped           
             type                 [ 7d202]
             low_pc               0xc0109af2 <sys_ptrace>
             high_pc              0xc010a0ea <do_syscall_trace>
             frame_base           location list [ 13a48]
 [ 862fa]      formal_parameter
               name                 "request"
               decl_file            1
               decl_line            234
               type                 [ 7d231]
               location             2 byte block
                [   0] breg4 28
 [ 86308]      formal_parameter
               name                 "pid"
               decl_file            1
               decl_line            234
               type                 [ 7d231]
               location             2 byte block
                [   0] breg4 32
 [ 86316]      formal_parameter
               name                 "addr"
               decl_file            1
               decl_line            234
               type                 [ 7d231]
               location             location list [ 13b40]
 [ 86325]      formal_parameter
               name                 "data"
               decl_file            1
               decl_line            234
               type                 [ 7d231]
               location             location list [ 13bc7]

Are the "location" fields for request and pid parameters reasonable?

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