Linux Operating System Course

PROJECT 1: Add segment_info system call to get thread segments information

Write Up

In this project, added system call segment_info was run under qemu with busybox 1.35.0 and linux kernel 6.0.5. You can compile and run the program main.c, linux kernel to check how does the thread segment arrange by following these steps.

Below is the sample output:

...
>>>>>> '0x7ffc10bc1000'-'0x7ffc10bc5000' unknown [vvar]
>>>>>> '0x7ffc10bc5000'-'0x7ffc10bc7000' unknown [vdso]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
˅˅˅˅˅˅˅˅˅˅˅˅˅˅˅ [User Mode] t2 thread id: 79 ˅˅˅˅˅˅˅˅˅˅˅˅˅˅
>>>>>> [code]:          '0x401845'
>>>>>> [data]:          '0x4e1110'
>>>>>> [bss]:           '0x4e33d0'
>>>>>> [heap]:          '0x1d16770'
>>>>>> [mmap]:          '0x7fa3955d4000'
>>>>>> [stack]:         '0x7fa394dd215a'
>>>>>>>>>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<<<<<<<<<<<<<<<
>>>>>> <start_code>:    '0x401000'
>>>>>> <end_code>:      '0x4b099d'
>>>>>> <start_data>:    '0x4dd768'
>>>>>> <end_data>:      '0x4e3370'
>>>>>> <start_brk>:     '0x1d15000'
>>>>>> <brk>:           '0x1d37000'
>>>>>> <mmap_base>:     '0x7fa3955d5000'
>>>>>> <thread_sp>:     '0x7fa394dd1d18'
>>>>>>>>>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<<<<<<<<<<<<<<<
>>>>>> '0x400000'-'0x401000' unknown
>>>>>> '0x401000'-'0x4b1000' code/text segment
>>>>>> '0x4b1000'-'0x4dd000' unknown
>>>>>> '0x4dd000'-'0x4e1000' data segment
>>>>>> '0x4e1000'-'0x4e4000' data segment
>>>>>> '0x4e4000'-'0x4ea000' bss segment
>>>>>> '0x1d15000'-'0x1d37000' heap segment
>>>>>> '0x7fa3945d2000'-'0x7fa3945d3000' mmap segment(shared library, thread stack...)
>>>>>> '0x7fa3945d3000'-'0x7fa394dd3000' t2 stack segment
>>>>>> '0x7fa394dd3000'-'0x7fa394dd4000' mmap segment(shared library, thread stack...)
>>>>>> '0x7fa394dd4000'-'0x7fa3955d5000' mmap segment(shared library, thread stack...)
>>>>>> '0x7ffc10a7f000'-'0x7ffc10aa0000' unknown
>>>>>> '0x7ffc10bc1000'-'0x7ffc10bc5000' unknown [vvar]
>>>>>> '0x7ffc10bc5000'-'0x7ffc10bc7000' unknown [vdso]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
˅˅˅˅˅˅˅˅˅˅˅˅˅˅˅ [User Mode] t1 thread id: 78 ˅˅˅˅˅˅˅˅˅˅˅˅˅˅
>>>>>> [code]:          '0x401845'
>>>>>> [data]:          '0x4e1110'
>>>>>> [bss]:           '0x4e33d0'
>>>>>> [heap]:          '0x1d16770'
...

PROJECT 2: Check how memory areas are shared by two processes that execute this program simultaneously

Write Up

Replacing multi-thread from project1/main.c with single-thread and sleep 10s

Modifying $PROJECT from project1 to /home/cliff/projects/course-linux-operating-system/project2

Testing command in qemu:

hush -c '/mnt/host_share/main & /mnt/host_share/main'

Output

˅˅˅˅˅˅˅˅˅˅˅˅˅˅˅ [User Mode] main thread id: 126 ˅˅˅˅˅˅˅˅˅˅˅˅˅˅
>>>>>> [code]:          '0x4017b5' -> '0x5c25000'
>>>>>> [data]:          '0x4c70f0' -> '0x6334000'
>>>>>> [bss]:           '0x4c93b0' -> '0x631a000'
>>>>>> [heap]:          '0x100b780' -> '0x5c07000'
>>>>>> [mmap]:          '0x7f3210b8a000' -> '0x631d000'
>>>>>> [lib]:           '0x40bf90' -> '0x40bf90'
>>>>>> [stack]:         '0x7ffeb725718a' -> '0x63ef000'
>>>>>>>>>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<<<<<<<<<<<<<<<
>>>>>> <start_code>:    '0x401000'
>>>>>> <end_code>:      '0x49885d'
>>>>>> <start_data>:    '0x4c37b0'
>>>>>> <end_data>:      '0x4c9350'
>>>>>> <start_brk>:     '0x1009000'
>>>>>> <brk>:           '0x102b000'
>>>>>> <mmap_base>:     '0x7f3210b8b000'
>>>>>> <thread_sp>:     '0x7ffeb7256d48'
>>>>>>>>>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<<<<<<<<<<<<<<<
>>>>>> '0x400000'-'0x401000' unknown
>>>>>> '0x401000'-'0x499000' code/text segment
>>>>>> '0x499000'-'0x4c2000' unknown
>>>>>> '0x4c3000'-'0x4c7000' data segment
>>>>>> '0x4c7000'-'0x4ca000' data segment
>>>>>> '0x4ca000'-'0x4cf000' bss segment
>>>>>> '0x1009000'-'0x102b000' heap segment
>>>>>> '0x7f3210b8a000'-'0x7f3210b8b000' mmap segment(shared library, thread stack...)
>>>>>> '0x7ffeb7237000'-'0x7ffeb7258000' main stack segment
>>>>>> '0x7ffeb72a1000'-'0x7ffeb72a5000' unknown [vvar]
>>>>>> '0x7ffeb72a5000'-'0x7ffeb72a7000' unknown [vdso]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
˅˅˅˅˅˅˅˅˅˅˅˅˅˅˅ [User Mode] main thread id: 125 ˅˅˅˅˅˅˅˅˅˅˅˅˅˅
>>>>>> [code]:          '0x4017b5' -> '0x5c25000'
>>>>>> [data]:          '0x4c70f0' -> '0x631e000'
>>>>>> [bss]:           '0x4c93b0' -> '0x632e000'
>>>>>> [heap]:          '0x5df780' -> '0x5c23000'
>>>>>> [mmap]:          '0x7fadf6258000' -> '0x6b92000'
>>>>>> [lib]:           '0x40bf90' -> '0x40bf90'
>>>>>> [stack]:         '0x7ffd18286aea' -> '0x63ec000'
>>>>>>>>>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<<<<<<<<<<<<<<<
>>>>>> <start_code>:    '0x401000'
>>>>>> <end_code>:      '0x49885d'
>>>>>> <start_data>:    '0x4c37b0'
>>>>>> <end_data>:      '0x4c9350'
>>>>>> <start_brk>:     '0x5dd000'
>>>>>> <brk>:           '0x5ff000'
>>>>>> <mmap_base>:     '0x7fadf6259000'
>>>>>> <thread_sp>:     '0x7ffd182866a8'
>>>>>>>>>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<<<<<<<<<<<<<<<
>>>>>> '0x400000'-'0x401000' unknown
>>>>>> '0x401000'-'0x499000' code/text segment
>>>>>> '0x499000'-'0x4c2000' unknown
>>>>>> '0x4c3000'-'0x4c7000' data segment
>>>>>> '0x4c7000'-'0x4ca000' data segment
>>>>>> '0x4ca000'-'0x4cf000' bss segment
>>>>>> '0x5dd000'-'0x5ff000' heap segment
>>>>>> '0x7fadf6258000'-'0x7fadf6259000' mmap segment(shared library, thread stack...)
>>>>>> '0x7ffd18267000'-'0x7ffd18288000' main stack segment
>>>>>> '0x7ffd1830f000'-'0x7ffd18313000' unknown [vvar]
>>>>>> '0x7ffd18313000'-'0x7ffd18315000' unknown [vdso]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^