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i#7046: Add padding to align loadable segments to page size in the core file. #7144

Merged
merged 7 commits into from
Dec 18, 2024
Merged

i#7046: Add padding to align loadable segments to page size in the core file. #7144

merged 7 commits into from
Dec 18, 2024

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ivankyluk
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@ivankyluk ivankyluk commented Dec 17, 2024 •
edited
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Align loadable segments to page size in the core file.

Based on https://man7.org/linux/man-pages/man5/elf.5.html:

p_align
This member holds the value to which the segments are
aligned in memory and in the file. Loadable process
segments must have congruent values for p_vaddr and
p_offset, modulo the page size. Values of zero and one
mean no alignment is required. Otherwise, p_align should
be a positive, integral power of two, and p_vaddr should
equal p_offset, modulo p_align.

The loabable segments alignment applies to both the address and the offset in the core file.

Testing output with readelf -l:

readelf -a logs/simple_app.1837029.00000000.elf
ELF Header:
  Magic:   7f 45 4c 46 02 01 01 03 00 00 00 00 00 00 00 00 
  Class:                             ELF64
  Data:                              2's complement, little endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - GNU
  ABI Version:                       0
  Type:                              CORE (Core file)
  Machine:                           Advanced Micro Devices X86-64
  Version:                           0x1
  Entry point address:               0x7fd28488a320
  Start of program headers:          64 (bytes into file)
  Start of section headers:          10432876 (bytes into file)
  Flags:                             0x0
  Size of this header:               64 (bytes)
  Size of program headers:           56 (bytes)
  Number of program headers:         47
  Size of section headers:           64 (bytes)
  Number of section headers:         47
  Section header string table index: 46

Section Headers:
  [Nr] Name              Type             Address           Offset
       Size              EntSize          Flags  Link  Info  Align
  [ 0]                   PROGBITS         00007fd03fe00000  00001000   <<<<<<<<<<
       0000000000040000  0000000000000000 WAM       0     0     8
  [ 1]                   PROGBITS         00007fd03fe41000  00041000
       0000000000006000  0000000000000000 WAM       0     0     8
  [ 2]                   PROGBITS         00007fd03fe49000  00047000
       0000000000004000  0000000000000000 WAM       0     0     8
  [ 3]                   PROGBITS         00007fd03fe51000  0004b000
       0000000000006000  0000000000000000 WAM       0     0     8
  [ 4]                   PROGBITS         00007fd03fe59000  00051000
       0000000000018000  0000000000000000 WAM       0     0     8
  [ 5]                   PROGBITS         00007fd03fe73000  00069000
       000000000000e000  0000000000000000 WAM       0     0     8
  [ 6]                   PROGBITS         00007fd03fe83000  00077000
       0000000000003000  0000000000000000 WAM       0     0     8
  [ 7]                   PROGBITS         00007fd03fe91000  0007a000
       000000000000c000  0000000000000000 WAM       0     0     8
  [ 8]                   PROGBITS         00007fd03fe9f000  00086000
       0000000000001000  0000000000000000 WAM       0     0     8
  [ 9]                   PROGBITS         00007fd03fea2000  00087000
       0000000000002000  0000000000000000 WAM       0     0     8
  [10]                   PROGBITS         00007fd03fea6000  00089000
       000000000000e000  0000000000000000 WAM       0     0     8
  [11]                   PROGBITS         00007fd03feb6000  00097000
       0000000000004000  0000000000000000 WAM       0     0     8
  [12]                   PROGBITS         00007fd03febe000  0009b000
       0000000000002000  0000000000000000 WAM       0     0     8
  [13]                   PROGBITS         00007fd03fec3000  0009d000
       0000000000001000  0000000000000000 WAM       0     0     8
  [14]                   PROGBITS         00007fd03fec8000  0009e000
       0000000000008000  0000000000000000 WAM       0     0     8
  [15]                   PROGBITS         00007fd03fed2000  000a6000
       0000000000018000  0000000000000000 WAM       0     0     8
  [16]                   PROGBITS         00007fd240000000  000be000
       0000000000008000  0000000000000000 WAM       0     0     8
  [17] /usr/local/g[...] PROGBITS         00007fd240008000  000c6000
       0000000000001000  0000000000000000  AM       0     0     8
  [18] /usr/local/g[...] PROGBITS         00007fd240009000  000c7000
       0000000000001000  0000000000000000 AXM       0     0     8
  [19] /usr/local/g[...] PROGBITS         00007fd24000a000  000c8000
       0000000000001000  0000000000000000  AM       0     0     8
  [20] /usr/local/g[...] PROGBITS         00007fd24000b000  000c9000
       0000000000002000  0000000000000000 WAM       0     0     8
  [21]                   PROGBITS         00007fd24000f000  000cb000
       0000000000001000  0000000000000000 WAM       0     0     8
  [22]                   PROGBITS         00007fd240017000  000cc000
       0000000000001000  0000000000000000 WAXM       0     0     8
  [23]                   PROGBITS         00007fd240018000  000cd000
       0000000000002000  0000000000000000 AXM       0     0     8
  [24]                   PROGBITS         00007fd24001a000  000cf000
       0000000000001000  0000000000000000 WAXM       0     0     8
  [25]                   PROGBITS         00007fd24001e000  000d0000
       0000000000001000  0000000000000000 WAXM       0     0     8
  [26]                   PROGBITS         00007fd24002e000  000d1000
       0000000000001000  0000000000000000 WAXM       0     0     8
  [27]                   PROGBITS         00007fd24003e000  000d2000
       0000000000001000  0000000000000000 WAXM       0     0     8
  [28]                   PROGBITS         00007fd240041000  000d3000
       0000000000001000  0000000000000000 WAXM       0     0     8
  [29]                   PROGBITS         00007fd240044000  000d4000
       0000000000001000  0000000000000000 WAM       0     0     8
  [30] /usr/local/g[...] PROGBITS         00007fd280000000  000d5000
       0000000000001000  0000000000000000  AM       0     0     8
  [31] /usr/local/g[...] PROGBITS         00007fd280001000  000d6000
       0000000000002000  0000000000000000 AXM       0     0     8
  [32] /usr/local/g[...] PROGBITS         00007fd280003000  000d8000
       0000000000001000  0000000000000000  AM       0     0     8
  [33] /usr/local/g[...] PROGBITS         00007fd280004000  000d9000
       0000000000002000  0000000000000000 WAM       0     0     8
  [34]                   PROGBITS         00007fd280007000  000db000
       0000000000400000  0000000000000000 WAM       0     0     8
  [35] /usr/local/g[...] PROGBITS         00007fd284200000  004db000
       000000000004f000  0000000000000000  AM       0     0     8
  [36] /usr/local/g[...] PROGBITS         00007fd28424f000  0052a000
       00000000002e9000  0000000000000000 AXM       0     0     8
  [37] /usr/local/g[...] PROGBITS         00007fd284538000  00813000
       00000000000cb000  0000000000000000  AM       0     0     8
  [38] /usr/local/g[...] PROGBITS         00007fd284603000  008de000
       0000000000082000  0000000000000000 WAM       0     0     8
  [39]                   PROGBITS         00007fd284685000  00960000
       0000000000039000  0000000000000000 WAM       0     0     8
  [40] /usr/lib/x86[...] PROGBITS         00007fd28486f000  00999000
       0000000000001000  0000000000000000  AM       0     0     8
  [41] /usr/lib/x86[...] PROGBITS         00007fd284870000  0099a000
       0000000000026000  0000000000000000 AXM       0     0     8
  [42] /usr/lib/x86[...] PROGBITS         00007fd284896000  009c0000
       000000000000b000  0000000000000000  AM       0     0     8
  [43] /usr/lib/x86[...] PROGBITS         00007fd2848a1000  009cb000
       0000000000004000  0000000000000000 WAM       0     0     8
  [44] [vdso]            PROGBITS         00007fd2848af000  009cf000
       0000000000002000  0000000000000000 AXM       0     0     8
  [45] [stack]           PROGBITS         00007ffcf3d5c000  009d1000
       0000000000022000  0000000000000000 WAM       0     0     8
  [46] shstrtab          STRTAB           0000000000000000  009f3000
       000000000000016c  0000000000000000           0     0     1
Key to Flags:
  W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
  L (link order), O (extra OS processing required), G (group), T (TLS),
  C (compressed), x (unknown), o (OS specific), E (exclude),
  R (retain), D (mbind), l (large), p (processor specific)

There are no section groups in this file.

Program Headers:
  Type           Offset             VirtAddr           PhysAddr
                 FileSiz            MemSiz              Flags  Align
  NOTE           0x0000000000000a88 0x0000000000000000 0x0000000000000000
                 0x0000000000000378 0x0000000000000378         0x2
  LOAD           0x0000000000001000 0x00007fd03fe00000 0x00007fd03fe00000
                 0x0000000000040000 0x0000000000040000  RW     0x1000
  LOAD           0x0000000000041000 0x00007fd03fe41000 0x00007fd03fe41000
                 0x0000000000006000 0x0000000000006000  RW     0x1000
  LOAD           0x0000000000047000 0x00007fd03fe49000 0x00007fd03fe49000
                 0x0000000000004000 0x0000000000004000  RW     0x1000
  LOAD           0x000000000004b000 0x00007fd03fe51000 0x00007fd03fe51000
                 0x0000000000006000 0x0000000000006000  RW     0x1000
  LOAD           0x0000000000051000 0x00007fd03fe59000 0x00007fd03fe59000
                 0x0000000000018000 0x0000000000018000  RW     0x1000
  LOAD           0x0000000000069000 0x00007fd03fe73000 0x00007fd03fe73000
                 0x000000000000e000 0x000000000000e000  RW     0x1000
  LOAD           0x0000000000077000 0x00007fd03fe83000 0x00007fd03fe83000
                 0x0000000000003000 0x0000000000003000  RW     0x1000
  LOAD           0x000000000007a000 0x00007fd03fe91000 0x00007fd03fe91000
                 0x000000000000c000 0x000000000000c000  RW     0x1000
  LOAD           0x0000000000086000 0x00007fd03fe9f000 0x00007fd03fe9f000
                 0x0000000000001000 0x0000000000001000  RW     0x1000
  LOAD           0x0000000000087000 0x00007fd03fea2000 0x00007fd03fea2000
                 0x0000000000002000 0x0000000000002000  RW     0x1000
  LOAD           0x0000000000089000 0x00007fd03fea6000 0x00007fd03fea6000
                 0x000000000000e000 0x000000000000e000  RW     0x1000
  LOAD           0x0000000000097000 0x00007fd03feb6000 0x00007fd03feb6000
                 0x0000000000004000 0x0000000000004000  RW     0x1000
  LOAD           0x000000000009b000 0x00007fd03febe000 0x00007fd03febe000
                 0x0000000000002000 0x0000000000002000  RW     0x1000
  LOAD           0x000000000009d000 0x00007fd03fec3000 0x00007fd03fec3000
                 0x0000000000001000 0x0000000000001000  RW     0x1000
  LOAD           0x000000000009e000 0x00007fd03fec8000 0x00007fd03fec8000
                 0x0000000000008000 0x0000000000008000  RW     0x1000
  LOAD           0x00000000000a6000 0x00007fd03fed2000 0x00007fd03fed2000
                 0x0000000000018000 0x0000000000018000  RW     0x1000
  LOAD           0x00000000000be000 0x00007fd240000000 0x00007fd240000000
                 0x0000000000008000 0x0000000000008000  RW     0x1000
  LOAD           0x00000000000c6000 0x00007fd240008000 0x00007fd240008000
                 0x0000000000001000 0x0000000000001000  R      0x1000
  LOAD           0x00000000000c7000 0x00007fd240009000 0x00007fd240009000
                 0x0000000000001000 0x0000000000001000  R E    0x1000
  LOAD           0x00000000000c8000 0x00007fd24000a000 0x00007fd24000a000
                 0x0000000000001000 0x0000000000001000  R      0x1000
  LOAD           0x00000000000c9000 0x00007fd24000b000 0x00007fd24000b000
                 0x0000000000002000 0x0000000000002000  RW     0x1000
  LOAD           0x00000000000cb000 0x00007fd24000f000 0x00007fd24000f000
                 0x0000000000001000 0x0000000000001000  RW     0x1000
  LOAD           0x00000000000cc000 0x00007fd240017000 0x00007fd240017000
                 0x0000000000001000 0x0000000000001000  RWE    0x1000
  LOAD           0x00000000000cd000 0x00007fd240018000 0x00007fd240018000
                 0x0000000000002000 0x0000000000002000  R E    0x1000
  LOAD           0x00000000000cf000 0x00007fd24001a000 0x00007fd24001a000
                 0x0000000000001000 0x0000000000001000  RWE    0x1000
  LOAD           0x00000000000d0000 0x00007fd24001e000 0x00007fd24001e000
                 0x0000000000001000 0x0000000000001000  RWE    0x1000
  LOAD           0x00000000000d1000 0x00007fd24002e000 0x00007fd24002e000
                 0x0000000000001000 0x0000000000001000  RWE    0x1000
  LOAD           0x00000000000d2000 0x00007fd24003e000 0x00007fd24003e000
                 0x0000000000001000 0x0000000000001000  RWE    0x1000
  LOAD           0x00000000000d3000 0x00007fd240041000 0x00007fd240041000
                 0x0000000000001000 0x0000000000001000  RWE    0x1000
  LOAD           0x00000000000d4000 0x00007fd240044000 0x00007fd240044000
                 0x0000000000001000 0x0000000000001000  RW     0x1000
  LOAD           0x00000000000d5000 0x00007fd280000000 0x00007fd280000000
                 0x0000000000001000 0x0000000000001000  R      0x1000
  LOAD           0x00000000000d6000 0x00007fd280001000 0x00007fd280001000
                 0x0000000000002000 0x0000000000002000  R E    0x1000
  LOAD           0x00000000000d8000 0x00007fd280003000 0x00007fd280003000
                 0x0000000000001000 0x0000000000001000  R      0x1000
  LOAD           0x00000000000d9000 0x00007fd280004000 0x00007fd280004000
                 0x0000000000002000 0x0000000000002000  RW     0x1000
  LOAD           0x00000000000db000 0x00007fd280007000 0x00007fd280007000
                 0x0000000000400000 0x0000000000400000  RW     0x1000
  LOAD           0x00000000004db000 0x00007fd284200000 0x00007fd284200000
                 0x000000000004f000 0x000000000004f000  R      0x1000
  LOAD           0x000000000052a000 0x00007fd28424f000 0x00007fd28424f000
                 0x00000000002e9000 0x00000000002e9000  R E    0x1000
  LOAD           0x0000000000813000 0x00007fd284538000 0x00007fd284538000
                 0x00000000000cb000 0x00000000000cb000  R      0x1000
  LOAD           0x00000000008de000 0x00007fd284603000 0x00007fd284603000
                 0x0000000000082000 0x0000000000082000  RW     0x1000
  LOAD           0x0000000000960000 0x00007fd284685000 0x00007fd284685000
                 0x0000000000039000 0x0000000000039000  RW     0x1000
  LOAD           0x0000000000999000 0x00007fd28486f000 0x00007fd28486f000
                 0x0000000000001000 0x0000000000001000  R      0x1000
  LOAD           0x000000000099a000 0x00007fd284870000 0x00007fd284870000
                 0x0000000000026000 0x0000000000026000  R E    0x1000
  LOAD           0x00000000009c0000 0x00007fd284896000 0x00007fd284896000
                 0x000000000000b000 0x000000000000b000  R      0x1000
  LOAD           0x00000000009cb000 0x00007fd2848a1000 0x00007fd2848a1000
                 0x0000000000004000 0x0000000000004000  RW     0x1000
  LOAD           0x00000000009cf000 0x00007fd2848af000 0x00007fd2848af000
                 0x0000000000002000 0x0000000000002000  R E    0x1000
  LOAD           0x00000000009d1000 0x00007ffcf3d5c000 0x00007ffcf3d5c000
                 0x0000000000022000 0x0000000000022000  RW     0x1000

 Section to Segment mapping:
  Segment Sections...
   00     
   01     
   02      
   03      
   04      
   05      
   06      
   07      
   08      
   09      
   10      
   11      
   12      
   13      
   14      
   15      
   16      
   17      
   18     /usr/local/google/home/kyluk/trace2checkpoint/dynamorio/build/suite/tests/bin/libclient.memory_dump_test.dll.so 
   19     /usr/local/google/home/kyluk/trace2checkpoint/dynamorio/build/suite/tests/bin/libclient.memory_dump_test.dll.so 
   20     /usr/local/google/home/kyluk/trace2checkpoint/dynamorio/build/suite/tests/bin/libclient.memory_dump_test.dll.so 
   21     /usr/local/google/home/kyluk/trace2checkpoint/dynamorio/build/suite/tests/bin/libclient.memory_dump_test.dll.so 
   22      
   23      
   24      
   25      
   26      
   27      
   28      
   29      
   30      
   31     /usr/local/google/home/kyluk/trace2checkpoint/dynamorio/build/suite/tests/bin/simple_app 
   32     /usr/local/google/home/kyluk/trace2checkpoint/dynamorio/build/suite/tests/bin/simple_app 
   33     /usr/local/google/home/kyluk/trace2checkpoint/dynamorio/build/suite/tests/bin/simple_app 
   34     /usr/local/google/home/kyluk/trace2checkpoint/dynamorio/build/suite/tests/bin/simple_app 
   35      
   36     /usr/local/google/home/kyluk/trace2checkpoint/dynamorio/build/lib64/debug/libdynamorio.so 
   37     /usr/local/google/home/kyluk/trace2checkpoint/dynamorio/build/lib64/debug/libdynamorio.so 
   38     /usr/local/google/home/kyluk/trace2checkpoint/dynamorio/build/lib64/debug/libdynamorio.so 
   39     /usr/local/google/home/kyluk/trace2checkpoint/dynamorio/build/lib64/debug/libdynamorio.so 
   40      
   41     /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 
   42     /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 
   43     /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 
   44     /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 
   45     [vdso] 
   46     [stack] 

There is no dynamic section in this file.

There are no relocations in this file.
No processor specific unwind information to decode

No version information found in this file.

Displaying notes found at file offset 0x00000a88 with length 0x00000378:
  Owner                Data size 	Description
  CORE                 0x00000150	NT_PRSTATUS (prstatus structure)
  CORE                 0x00000200	NT_FPREGSET (floating point registers)

Without the padding, the offset of the first section may not be page size aligned, i.e. 0xe00 in the following case:

Section Headers:
  [Nr] Name              Type             Address           Offset
       Size              EntSize          Flags  Link  Info  Align
  [ 0]                   PROGBITS         00007f0018e00000  00000e00    <<<<<<<<<<
       0000000000040000  0000000000000000 WAM       0     0     8

Issue: #7046

derekbruening
derekbruening approved these changes Dec 17, 2024
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@ivankyluk ivankyluk changed the title i#7046: Add padding to align section data to page size. i#7046: Add padding to align loadable segments to page size in the core file. Dec 17, 2024
derekbruening
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@ivankyluk ivankyluk merged commit 291ec3d into master Dec 18, 2024
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@ivankyluk ivankyluk deleted the i7046-add-padding-to-align-sections-on-page-size branch December 18, 2024 01:28
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@derekbruening derekbruening derekbruening approved these changes

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@ivankyluk @derekbruening