Date: Sun, 21 Jul 2024 20:58:18 -0700 From: Mark Millard <marklmi@yahoo.com> To: John F Carr <jfc@mit.edu>, Konstantin Belousov <kostikbel@gmail.com>, Baptiste Daroussin <bapt@FreeBSD.org> Cc: arm@freebsd.org, current@freebsd.org Subject: Re: armv7-on-aarch64 stuck at urdlck: I got a replication of the "ampere2" bulk build hangup problem on a Windows DevKit 2023 Message-ID: <705AE360-C1C3-4B54-B6EE-FC81548D46B8@yahoo.com> In-Reply-To: <DA56EE85-F50E-46F0-A8B4-538C698A4058@yahoo.com> References: <A3BBDBA3-FF7E-47B8-8B45-C3351918FC08@yahoo.com> <8214703E-AB28-4FB3-A3DD-03C87363D8C6@yahoo.com> <E40B106D-30B7-49DC-8540-911A56E53FCA@yahoo.com> <BFCA474F-78D4-4E98-8A9B-B92C2DB6B0DE@yahoo.com> <E40627DC-35A2-4D5E-A85C-73D7FFD426DF@yahoo.com> <A208F7C8-0D9E-402C-BB85-A5022B37E3EC@yahoo.com> <Zpt79jpCFDSiffcy@kib.kiev.ua> <8E9579B7-2ABF-4446-B65E-E993E7B67C5C@yahoo.com> <CBF08B5A-A701-4D8E-AE96-3CB54137B14E@yahoo.com> <D02F1ADE-4E1B-4DAF-81C0-8EBD5315FC66@yahoo.com> <9E98F6F6-6896-4958-9D88-FF68C4AB57F2@mit.edu> <DA56EE85-F50E-46F0-A8B4-538C698A4058@yahoo.com>
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I found a significant difference in my failing vs. working
armv7 contexts as installed: Presence vs. Lack of a .symtab
entry for the symbol _rtld_get_stack_prot in
/libexec/ld-elf.so.1 .
gdb inspection of operation shows distinctions based on
the difference.
This is related to the code:
(gdb) list 140
135 void
136 _thr_stack_fix_protection(struct pthread *thrd)
137 {
138=09
139 mprotect((char *)thrd->attr.stackaddr_attr +
140 round_up(thrd->attr.guardsize_attr),
141 round_up(thrd->attr.stacksize_attr),
142 _rtld_get_stack_prot());
143 }
Working context (Personal build):
NOTE THE .symtab ENTRY BELOW. It allows the gdb run to work:
# readelf -a /libexec/ld-elf.so.1 | grep -E "(^[^ =
0-9]|.*_rtld_get_stack_prot)" | less
ELF Header:
Elf file type is DYN (Shared object file)
Entry point 0x14548
There are 10 program headers, starting at offset 52
Program Headers:
There are 24 section headers, starting at offset 0x1f2b8:
Section Headers:
Key to Flags:
Dynamic section at offset 0x199f8 contains 15 entries:
Relocation section (.rel.dyn):
r_offset r_info r_type st_value st_name
Symbol table '.dynsym' contains 27 entries:
5: 000000000001b9ac 16 FUNC GLOBAL DEFAULT 11 =
_rtld_get_stack_prot@@FBSDprivate_1.0 (11)
Symbol table '.symtab' contains 911 entries:
903: 000000000001b9ac 16 FUNC GLOBAL DEFAULT 11 =
_rtld_get_stack_prot
Notes at offset 0x00000174 with length 0x00000018:
Histogram for bucket list length (total of 6 buckets):
Histogram for bucket list length (total of 27 buckets):
Version symbol section (.gnu.version):
Version definition section (.gnu.version_d):
Attribute Section: aeabi
File Attributes
Breakpoint 8.3, _thr_stack_fix_protection (thrd=3D0x2006f000) at =
/usr/main-src/lib/libthr/thread/thr_stack.c:139
139 mprotect((char *)thrd->attr.stackaddr_attr +
(gdb) si
141 round_up(thrd->attr.stacksize_attr),
(gdb)=20
140 round_up(thrd->attr.guardsize_attr),
(gdb)=20
round_up (size=3D4096) at =
/usr/main-src/lib/libthr/thread/thr_stack.c:129
129 if (size % _thr_page_size !=3D 0)
(gdb)=20
0x201110b8 129 if (size % _thr_page_size !=3D 0)
130 size =3D ((size / _thr_page_size) + 1) *
(gdb)=20
0x201110c0 130 size =3D ((size / =
_thr_page_size) + 1) *
(gdb)=20
0x201110c4 in round_up (size=3D4096) at =
/usr/main-src/lib/libthr/thread/thr_stack.c:130
130 size =3D ((size / _thr_page_size) + 1) *
(gdb)=20
0x201110c8 130 size =3D ((size / =
_thr_page_size) + 1) *
(gdb)=20
round_up (size=3D67108864) at =
/usr/main-src/lib/libthr/thread/thr_stack.c:129
129 if (size % _thr_page_size !=3D 0)
(gdb)=20
0x201110d0 in round_up (size=3D4096) at =
/usr/main-src/lib/libthr/thread/thr_stack.c:129
129 if (size % _thr_page_size !=3D 0)
(gdb)=20
0x201110d4 in round_up (size=3D67108864) at =
/usr/main-src/lib/libthr/thread/thr_stack.c:129
129 if (size % _thr_page_size !=3D 0)
(gdb)=20
0x201110d8 129 if (size % _thr_page_size !=3D 0)
(gdb)=20
0x201110dc in round_up (size=3D4096) at =
/usr/main-src/lib/libthr/thread/thr_stack.c:129
129 if (size % _thr_page_size !=3D 0)
(gdb)=20
0x201110e0 129 if (size % _thr_page_size !=3D 0)
(gdb)=20
_thr_stack_fix_protection (thrd=3D0x2006f000) at =
/usr/main-src/lib/libthr/thread/thr_stack.c:139
139 mprotect((char *)thrd->attr.stackaddr_attr +
(gdb)=20
142 _rtld_get_stack_prot());
(gdb)=20
0x20114880 in ?? () from /lib/libthr.so.3
(gdb)=20
0x20114884 in ?? () from /lib/libthr.so.3
(gdb)=20
0x20114888 in ?? () from /lib/libthr.so.3
(gdb)=20
Breakpoint 9.1, _rtld_get_stack_prot () at =
/usr/main-src/libexec/rtld-elf/rtld.c:5884
5884 return (stack_prot);
(gdb)=20
0x2005b9b0 5884 return (stack_prot);
(gdb)=20
0x2005b9b4 5884 return (stack_prot);
Failing context (Official PkgBase build):
NOTE THE *LACK OF* THE .symtab ENTRY ABOVE. _rtld_bind_start ends
up in use instead, which looks to lead to the gdb run not working.
IN FACT, NOTE THE LACK OF ANY "Symbol table '.symtab' contains"
TEXT AT ALL!
# readelf -a /libexec/ld-elf.so.1 | grep -E "(^[^ =
0-9]|.*_rtld_get_stack_prot)" | less
ELF Header:
Elf file type is DYN (Shared object file)
Entry point 0x147b0
There are 10 program headers, starting at offset 52
Program Headers:
There are 22 section headers, starting at offset 0x1a960:
Section Headers:
Key to Flags:
Dynamic section at offset 0x1a4cc contains 15 entries:
Relocation section (.rel.dyn):
r_offset r_info r_type st_value st_name
Symbol table '.dynsym' contains 27 entries:
5: 000000000001bcd8 16 FUNC GLOBAL DEFAULT 11 =
_rtld_get_stack_prot@@FBSDprivate_1.0 (11)
Notes at offset 0x00000174 with length 0x00000018:
Histogram for bucket list length (total of 6 buckets):
Histogram for bucket list length (total of 27 buckets):
Version symbol section (.gnu.version):
Version definition section (.gnu.version_d):
Attribute Section: aeabi
File Attributes
Breakpoint 2.3, _thr_stack_fix_protection (thrd=3D0x20070000) at =
/home/pkgbuild/worktrees/main/lib/libthr/thread/thr_stack.c:140
140 round_up(thrd->attr.guardsize_attr),
(gdb) si
139 mprotect((char *)thrd->attr.stackaddr_attr +
(gdb)=20
141 round_up(thrd->attr.stacksize_attr),
(gdb)=20
round_up (size=3D4096) at =
/home/pkgbuild/worktrees/main/lib/libthr/thread/thr_stack.c:129
129 if (size % _thr_page_size !=3D 0)
(gdb)=20
130 size =3D ((size / _thr_page_size) + 1) *
(gdb)=20
129 if (size % _thr_page_size !=3D 0)
(gdb)=20
130 size =3D ((size / _thr_page_size) + 1) *
(gdb)=20
0x20112ef8 130 size =3D ((size / =
_thr_page_size) + 1) *
(gdb)=20
0x20116b60 in ?? () from /lib/libthr.so.3
(gdb)=20
0x20116b64 in ?? () from /lib/libthr.so.3
(gdb)=20
0x20116b68 in ?? () from /lib/libthr.so.3
(gdb)=20
0x20116760 in ?? () from /lib/libthr.so.3
(gdb)=20
0x20116764 in ?? () from /lib/libthr.so.3
(gdb)=20
0x20116768 in ?? () from /lib/libthr.so.3
(gdb)=20
0x2011676c in ?? () from /lib/libthr.so.3
(gdb)=20
_rtld_bind_start () at =
/home/pkgbuild/worktrees/main/libexec/rtld-elf/arm/rtld_start.S:78
78 stmdb sp!,{r0-r5,sl,fp}
(gdb) si
80 sub r1, ip, lr /* r1 =3D 4 * (n + 1) */
(gdb)=20
81 sub r1, r1, #4 /* r1 =3D 4 * n */
(gdb)=20
82 add r1, r1, r1 /* r1 =3D 8 * n */
(gdb)=20
84 ldr r0, [lr, #-4] /* get obj ptr from =
GOT[1] */
(gdb)=20
85 mov r4, ip /* save GOT location */
(gdb)=20
87 mov r5, sp /* Save the stack =
pointer */
(gdb)=20
88 bic sp, sp, #7 /* Align the stack =
pointer */
(gdb)=20
_rtld_bind_start () at =
/home/pkgbuild/worktrees/main/libexec/rtld-elf/arm/rtld_start.S:89
89 bl _rtld_bind /* Call the binder */
I have not checked for other .symtab entry problems.
Nor have I figured out why the installed materials are
different for Symbol table '.symtab' . So this is not
yet root-cause information.
=3D=3D=3D
Mark Millard
marklmi at yahoo.com
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