On Wed, 05 Jan 2011, Carlos O'Donell wrote:
> >> With the above, I get the following INEQUIVALENT ALIASES messages:
> >>
> >> Jan 1 10:23:19 gsyprf11 kernel: [135942.140000] INEQUIVALENT ALIASES 0x406b1000 and 0x406b0000 in file libc-2.11.2.so
> >> Jan 1 10:23:19 gsyprf11 kernel: [135942.224000] INEQUIVALENT ALIASES 0x406b1000 and 0x406b0000 in file libc-2.11.2.so
> >
> > This is what I see in the tasks maps file in /proc:
> >
> > 00010000-00011000 r-xp 00000000 08:30 6613687 /home2/dave/inequiv/xxx1
> > 00011000-00012000 rwxp 00000000 08:30 6613687 /home2/dave/inequiv/xxx1
> > 40000000-40005000 rw-p 00000000 00:00 0
> > 4002b000-4004b000 r-xp 00000000 08:03 2502157 /lib/ld-2.11.2.so
> > 4004b000-4004f000 rwxp 0001f000 08:03 2502157 /lib/ld-2.11.2.so
> > 4004f000-40050000 rwxp 00000000 00:00 0
> > 40138000-40291000 r-xp 00000000 08:03 2502172 /lib/libc-2.11.2.so
> > 40291000-40298000 rwxp 00158000 08:03 2502172 /lib/libc-2.11.2.so
> > 40298000-4029a000 rwxp 00000000 00:00 0
> > fe09b000-fe0be000 rwxp 00000000 00:00 0 [stack]
> >
> > As can be seen, there are duplicate maps with different protections for xxx1,
> > etc. So, it's clear why we have the inequivalent aliases. The map can
> > be accessed by the application (probably just for lines in the cache).
> > I have seen some discussions that even a read may lead to cache corruption.
> >
> > These inequivalent maps are coming from glibc:
> >
> > dave@gsyprf11:~/inequiv$ strace /lib/ld-2.11.2.so ./xxx1
> > execve("/lib/ld-2.11.2.so", ["/lib/ld-2.11.2.so", "./xxx1"], [/* 17 vars */]) = 0
> > brk(0) = 0x4119a000
> > open("./xxx1", O_RDONLY) = 3
> > read(3, "\177ELF\1\2\1\3\0\0\0\0\0\0\0\0\0\2\0\17\0\0\0\1\0\1\3T\0\0\0004"..., 512) = 512
> > fstat64(3, {st_mode=0, st_size=4380866642020, ...}) = 0
> > getcwd("/home2/dave/inequiv", 128) = 20
> > mmap(0x10000, 4096, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0) = 0x10000
> > mmap(0x11000, 4096, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0) = 0x11000
> > ...
> >
> > Carlos what do you think? arch_get_unmapped_area() accepts MAP_FIXED
> > requests even if it would violate cache aliasing constraints. I don't
> > understand the purpose of the region at 0x11000.
>
> I'm currently on the South Rim of the Grand Canyon with limited access
> to my systems. I'll be back in touch near the end of January and look
> into this.
Nice!
> What does the application look like e.g. readelf -a?
See below.
> The 0x11000 region looks like .data?
Yes. However, the 0x11000 region also maps to the same physical
address as the region at 0x10000. Thus, the inequivalent mapping.
The data starts at 0x11890. It appears the linker has rounded up
the start of the data by 4KB (one page).
Maybe the fix is to round up the start of the data to the next 4GB
boundary in the linker. This would make the alias boundaries
equivalent.
Dave
--
J. David Anglin dave.anglin@xxxxxxxxxxxxxx
National Research Council of Canada (613) 990-0752 (FAX: 952-6602)
ELF Header:
Magic: 7f 45 4c 46 01 02 01 03 00 00 00 00 00 00 00 00
Class: ELF32
Data: 2's complement, big endian
Version: 1 (current)
OS/ABI: UNIX - Linux
ABI Version: 0
Type: EXEC (Executable file)
Machine: HPPA
Version: 0x1
Entry point address: 0x10354
Start of program headers: 52 (bytes into file)
Start of section headers: 2884 (bytes into file)
Flags: 0x210, PA-RISC 1.1
Size of this header: 52 (bytes)
Size of program headers: 32 (bytes)
Number of program headers: 7
Size of section headers: 40 (bytes)
Number of section headers: 31
Section header string table index: 28
Section Headers:
[Nr] Name Type Addr Off Size ES Flg Lk Inf Al
[ 0] NULL 00000000 000000 000000 00 0 0 0
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[ 2] .note.ABI-tag NOTE 00010124 000124 000020 00 A 0 0 4
[ 3] .note.gnu.build-i NOTE 00010144 000144 000000 00 A 0 0 4
[ 4] .hash HASH 00010144 000144 000034 04 A 5 0 4
[ 5] .dynsym DYNSYM 00010178 000178 000080 10 A 6 1 4
[ 6] .dynstr STRTAB 000101f8 0001f8 000080 00 A 0 0 1
[ 7] .gnu.version VERSYM 00010278 000278 000010 02 A 5 0 2
[ 8] .gnu.version_r VERNEED 00010288 000288 000020 00 A 6 1 4
[ 9] .rela.dyn RELA 000102a8 0002a8 00000c 0c A 5 0 4
[10] .rela.plt RELA 000102b4 0002b4 000048 0c A 5 23 4
[11] .init PROGBITS 000102fc 0002fc 000048 00 AX 0 0 4
[12] .text PROGBITS 00010344 000344 0003e4 00 AX 0 0 4
[13] .fini PROGBITS 00010728 000728 000028 00 AX 0 0 4
[14] .rodata PROGBITS 00010750 000750 000018 00 A 0 0 4
[15] .PARISC.unwind PROGBITS 00010768 000768 0000e0 04 A 0 12 4
[16] .eh_frame_hdr PROGBITS 00010848 000848 000014 00 A 0 0 4
[17] .eh_frame PROGBITS 0001085c 00085c 000034 00 A 0 0 4
[18] .ctors PROGBITS 00011890 000890 000008 00 WA 0 0 4
[19] .dtors PROGBITS 00011898 000898 000008 00 WA 0 0 4
[20] .jcr PROGBITS 000118a0 0008a0 000004 00 WA 0 0 4
[21] .dynamic DYNAMIC 000118a4 0008a4 0000c8 08 WA 6 0 4
[22] .data PROGBITS 0001196c 00096c 000008 00 WA 0 0 4
[23] .plt PROGBITS 00011974 000974 00004c 08 WAX 0 0 4
[24] .got PROGBITS 000119c0 0009c0 00001c 04 WA 0 0 4
[25] .bss NOBITS 000119dc 0009dc 000014 00 WA 0 0 4
[26] .note NOTE 00000000 0009dc 000028 00 0 0 1
[27] .comment PROGBITS 00000000 000a04 000038 01 MS 0 0 1
[28] .shstrtab STRTAB 00000000 000a3c 000106 00 0 0 1
[29] .symtab SYMTAB 00000000 00101c 0004c0 10 30 56 4
[30] .strtab STRTAB 00000000 0014dc 0002b1 00 0 0 1
Key to Flags:
W (write), A (alloc), X (execute), M (merge), S (strings)
I (info), L (link order), G (group), T (TLS), E (exclude), x (unknown)
O (extra OS processing required) o (OS specific), p (processor specific)
There are no section groups in this file.
Program Headers:
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PHDR 0x000034 0x00010034 0x00010034 0x000e0 0x000e0 R E 0x4
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[Requesting program interpreter: /lib/ld.so.1]
LOAD 0x000000 0x00010000 0x00010000 0x00890 0x00890 R E 0x1000
LOAD 0x000890 0x00011890 0x00011890 0x0014c 0x00160 RWE 0x1000
DYNAMIC 0x0008a4 0x000118a4 0x000118a4 0x000c8 0x000c8 RW 0x4
NOTE 0x000124 0x00010124 0x00010124 0x00020 0x00020 R 0x4
GNU_EH_FRAME 0x000848 0x00010848 0x00010848 0x00014 0x00014 R 0x4
Section to Segment mapping:
Segment Sections...
00
01 .interp
02 .interp .note.ABI-tag .note.gnu.build-id .hash .dynsym .dynstr .gnu.version .gnu.version_r .rela.dyn .rela.plt .init .text .fini .rodata .PARISC.unwind .eh_frame_hdr .eh_frame
03 .ctors .dtors .jcr .dynamic .data .plt .got .bss
04 .dynamic
05 .note.ABI-tag
06 .eh_frame_hdr
Dynamic section at offset 0x8a4 contains 20 entries:
Tag Type Name/Value
0x00000001 (NEEDED) Shared library: [libc.so.6]
0x0000000c (INIT) 0x1030c
0x0000000d (FINI) 0x10728
0x00000004 (HASH) 0x10144
0x00000005 (STRTAB) 0x101f8
0x00000006 (SYMTAB) 0x10178
0x0000000a (STRSZ) 128 (bytes)
0x0000000b (SYMENT) 16 (bytes)
0x00000003 (PLTGOT) 0x1196c
0x00000015 (DEBUG) 0x0
0x00000002 (PLTRELSZ) 72 (bytes)
0x00000014 (PLTREL) RELA
0x00000017 (JMPREL) 0x102b4
0x00000007 (RELA) 0x102a8
0x00000008 (RELASZ) 12 (bytes)
0x00000009 (RELAENT) 12 (bytes)
0x6ffffffe (VERNEED) 0x10288
0x6fffffff (VERNEEDNUM) 1
0x6ffffff0 (VERSYM) 0x10278
0x00000000 (NULL) 0x0
Relocation section '.rela.dyn' at offset 0x2a8 contains 1 entries:
Offset Info Type Sym.Value Sym. Name + Addend
000119d0 00000401 R_PARISC_DIR32 000119c0 _GLOBAL_OFFSET_TABLE_ + 0
Relocation section '.rela.plt' at offset 0x2b4 contains 6 entries:
Offset Info Type Sym.Value Sym. Name + Addend
00011974 00000181 R_PARISC_IPLT 000105ec __libc_csu_fini + 0
0001197c 00000281 R_PARISC_IPLT 00010724 __gmon_start__ + 0
00011984 00000381 R_PARISC_IPLT 00000000 _Jv_RegisterClasses + 0
0001198c 00000581 R_PARISC_IPLT 000105f0 __libc_csu_init + 0
00011994 00000681 R_PARISC_IPLT 00000000 __libc_start_main + 0
0001199c 00000781 R_PARISC_IPLT 000104a0 main + 0
Unwind section '.PARISC.unwind' at offset 0x768 contains 14 entries:
<_init>: [0x1030c-0x10340]
Entry_GR=1 Save_RP Total_frame_size=8
<__do_global_dtors_aux>: [0x103a8-0x10438]
Entry_GR=4 Save_RP Total_frame_size=8
<call___do_global_dtors_aux>: [0x1043c-0x1044c]
Save_RP Total_frame_size=8
<frame_dummy>: [0x10450-0x10488]
Save_RP Total_frame_size=8
<call_frame_dummy>: [0x1048c-0x1049c]
Save_RP Total_frame_size=8
<main>: [0x104a0-0x104bc]
Entry_GR=1 Save_SP Total_frame_size=8
<main+20>: [0x104c0-0x104d4]
Millicode
<__canonicalize_funcptr_for_compare>: [0x104d8-0x105e8]
Entry_GR=2 Save_RP Total_frame_size=8
<__libc_csu_fini>: [0x105ec-0x105ec]
<__libc_csu_init>: [0x105f0-0x10694]
Entry_GR=7 Save_RP Total_frame_size=16
<__do_global_ctors_aux>: [0x10698-0x1070c]
Entry_GR=3 Save_RP Total_frame_size=16
<call___do_global_ctors_aux>: [0x10710-0x10720]
Save_RP Total_frame_size=8
<__gmon_start__>: [0x10724-0x10724]
<_fini>: [0x10728-0x1074c]
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Symbol table '.dynsym' contains 8 entries:
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7: 000104a0 32 FUNC GLOBAL DEFAULT 12 main
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23: 00011974 0 SECTION LOCAL DEFAULT 23
24: 000119c0 0 SECTION LOCAL DEFAULT 24
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Histogram for bucket list length (total of 3 buckets):
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Notes at offset 0x00000124 with length 0x00000020:
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