Re: please help

["Peter Teoh" <htmldeveloper at gmail dot com>]

Alternatively, as Frank earlier said in another email:

 probe process("a.out").function("*") { log ($$parms) }

On Tue, Oct 14, 2008 at 11:14 AM, Peter Teoh <htmldeveloper@gmail.com> wrote:
> first to use systemtap, u need to roughly know which kernel APIs u
> want to trace.   to do that, u can use "strace" to trace the userspace
> execution of the program, and from the system call output, (usually
> :-)) add the sys_xxx to derive the kernel API version, eg, for
> execve() it is sys_execve():
>
> The following is your program:
>
> /root>strace ./a.out
> execve("./a.out", ["./a.out"], [/* 28 vars */]) = 0
> brk(0)                                  = 0x804a000
> access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
> mmap2(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1,
> 0) = 0xb7ef5000
> access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
> open("/etc/ld.so.cache", O_RDONLY)      = 3
> fstat64(3, {st_mode=S_IFREG|0644, st_size=54870, ...}) = 0
> mmap2(NULL, 54870, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7ee7000
> close(3)                                = 0
> access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
> open("/lib/tls/i686/cmov/libc.so.6", O_RDONLY) = 3
> read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\0`\1\000"...,
> 512) = 512
> fstat64(3, {st_mode=S_IFREG|0644, st_size=1307104, ...}) = 0
> mmap2(NULL, 1312164, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE,
> 3, 0) = 0xb7da6000
> mmap2(0xb7ee1000, 12288, PROT_READ|PROT_WRITE,
> MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x13b) = 0xb7ee1000
> mmap2(0xb7ee4000, 9636, PROT_READ|PROT_WRITE,
> MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb7ee4000
> close(3)                                = 0
> mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1,
> 0) = 0xb7da5000
> set_thread_area({entry_number:-1 -> 6, base_addr:0xb7da56c0,
> limit:1048575, seg_32bit:1, contents:0, read_exec_only:0,
> limit_in_pages:1, seg_not_present:0, useable:1}) = 0
> mprotect(0xb7ee1000, 4096, PROT_READ)   = 0
> munmap(0xb7ee7000, 54870)               = 0
> fstat64(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 1), ...}) = 0
> mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1,
> 0) = 0xb7ef4000
> write(1, "Test kernel", 11Test kernel)             = 11
> exit_group(11)                          = ?
>
> And sys_execve() in arch/x86/kernel/process_32.c is your start (mine
> kernel is 2.6.20).   Well, it will be a long long path towards full
> understanding even of this simple program.   Alternatively, pick a
> topic of interest, and understand in greater depth about it.   Eg,
> tracing the filesystem VFS APIs etc.
>
> On Sat, Oct 11, 2008 at 10:12 PM, siddharam suresh
> <siddharam.s.t@gmail.com> wrote:
>> i want visualize what all the stuffs happening inside the Linux kernel
>> when this program is executed
>>
>>
>> #include<stdio.h>
>> void main()
>> {
>> printf("Test kernel");  <-- here i want know what are all the system
>> calls and the kernel data structure kernel is used by the kernel. Is
>> it possible to put break points here and can we see what are the
>> things happening inside the kernel when printf is executed
>>
>> }
>>
>>
>> is it possible to put break points in side the my program using the
>> system tap i want to visualize what are system calls and kernel data
>> structure used by particular statement.
>>
>> as above stated test.c program i what see what is happening inside the
>> kernel when printf("Test Kernel"); is executed .This because when the
>> my program become large it will show so many information which may not
>> be use full to me and very difficult to get the particular
>> information.Is there any facilities like step in and step out in
>> system tap
>>
>>
>>
>> thank you in advance
>> waiting great response
>>
>
>
>
> --
> Regards,
> Peter Teoh
>



-- 
Regards,
Peter Teoh