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* [Bug nptl/14568] New: Sparc64: disagreement between gdb64 and libpthread.so on where to look for %g7
@ 2012-09-10 14:05 ilmalakhov at yandex dot ru
2012-09-11 8:43 ` [Bug nptl/14568] " ilmalakhov at yandex dot ru
` (5 more replies)
0 siblings, 6 replies; 7+ messages in thread
From: ilmalakhov at yandex dot ru @ 2012-09-10 14:05 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=14568
Bug #: 14568
Summary: Sparc64: disagreement between gdb64 and libpthread.so
on where to look for %g7
Product: glibc
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: nptl
AssignedTo: unassigned@sourceware.org
ReportedBy: ilmalakhov@yandex.ru
CC: drepper.fsp@gmail.com
Classification: Unclassified
Hi.
There seems to be a disagreement between `gdb64' for Sparc64 and
`libpthread.so' on where to look for `%g7' when setting `th_unique' in
libthread_db. First of all, let's consider a situation when a 64-bit program is
being debugged.
According to `nptl/sysdeps/sparc/tls.h'
. . .
# define DB_THREAD_SELF \
REGISTER (32, 32, REG_G7 * 4, 0) REGISTER (64, 64, REG_G7 * 8, 0)
. . .
and `sysdeps/unix/sysv/linux/sparc/sys/ucontext.h'
. . .
define REG_G7 (10)
. . .
the value of `%g7' should be fetched from offset `8 * 10 == 0x50' of the `regs'
array filled in by `ps_lgetregs ()' (see the code of `__td_ta_lookup_th_unique
()' in `libthread_db').
On the other hand, `ps_lgetregs ()' (it is implemented in gdb) ends up
invoking `sparc64_collect_gregset ()' which eventually fills in this array:
. . .
if ((regnum >= SPARC_G1_REGNUM && regnum <= SPARC_O7_REGNUM) || regnum == -1)
{
int offset = gregset->r_g1_offset;
if (sparc32)
offset += 4;
/* %g0 is always zero. */
for (i = SPARC_G1_REGNUM; i <= SPARC_O7_REGNUM; i++)
{
if (regnum == i || regnum == -1)
regcache_raw_collect (regcache, i, regs + offset);
offset += 8;
}
}
. . .
Taking into account that `gregset' turns out to be a pointer to
`sparc64_linux_ptrace_gregset' and that the `r_g1_offset' field of the latter
equals to zero (see `sparc64-linux-nat.c'), `%g7' is actually placed at offset
`6 * 8 == 0x30' rather than 0x50.
In practice this leads to "cannot get thread info" gdb failures when debugging
multithreaded apps. To fix this either `REGISTER (64, 64, 6 * 8, 0)' should\
be specified in `libpthread' or `r_g1_offset' fixed appropriately in `gdb64'.
As for the case of a 32-bit app being debugged with `gdb64', there is another
issue in addition to the described above. I believe that the "size" element of
`_thread_db_register64' should be set to 32 rather than to 64 in 32-bit
`libpthread.so' and that its "regofs" element should be increased by 4 (see the
corresponding code in `gdb64' above'):
# if __WORDSIZE == 64
# define DB_THREAD_SELF \
. . . REGISTER (64, 64, 6 * 8, 0)
# else /* __WORDSIZE == 32 */
# define DB_THREAD_SELF \
. . . REGISTER (64, 32, 6 * 8 + 4, 0)
# endif /* __WORDSIZE == 32 */
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* [Bug nptl/14568] Sparc64: disagreement between gdb64 and libpthread.so on where to look for %g7
2012-09-10 14:05 [Bug nptl/14568] New: Sparc64: disagreement between gdb64 and libpthread.so on where to look for %g7 ilmalakhov at yandex dot ru
@ 2012-09-11 8:43 ` ilmalakhov at yandex dot ru
2012-09-28 7:36 ` davem at davemloft dot net
` (4 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: ilmalakhov at yandex dot ru @ 2012-09-11 8:43 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=14568
Il'ya Malakhov <ilmalakhov at yandex dot ru> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |davem at davemloft dot net
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* [Bug nptl/14568] Sparc64: disagreement between gdb64 and libpthread.so on where to look for %g7
2012-09-10 14:05 [Bug nptl/14568] New: Sparc64: disagreement between gdb64 and libpthread.so on where to look for %g7 ilmalakhov at yandex dot ru
2012-09-11 8:43 ` [Bug nptl/14568] " ilmalakhov at yandex dot ru
@ 2012-09-28 7:36 ` davem at davemloft dot net
2012-09-28 7:38 ` davem at davemloft dot net
` (3 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: davem at davemloft dot net @ 2012-09-28 7:36 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=14568
--- Comment #1 from David S. Miller <davem at davemloft dot net> 2012-09-28 07:35:40 UTC ---
Thanks for this report, your analysis is excellent.
I'll think about whether this is better to fix in GDB or glibc.
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* [Bug nptl/14568] Sparc64: disagreement between gdb64 and libpthread.so on where to look for %g7
2012-09-10 14:05 [Bug nptl/14568] New: Sparc64: disagreement between gdb64 and libpthread.so on where to look for %g7 ilmalakhov at yandex dot ru
2012-09-11 8:43 ` [Bug nptl/14568] " ilmalakhov at yandex dot ru
2012-09-28 7:36 ` davem at davemloft dot net
@ 2012-09-28 7:38 ` davem at davemloft dot net
2012-09-28 7:39 ` davem at davemloft dot net
` (2 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: davem at davemloft dot net @ 2012-09-28 7:38 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=14568
--- Comment #2 from David S. Miller <davem at davemloft dot net> 2012-09-28 07:38:15 UTC ---
Thanks for this report, your analysis is excellent.
I'll think about whether this is better to fix in GDB or glibc.
--
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^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug nptl/14568] Sparc64: disagreement between gdb64 and libpthread.so on where to look for %g7
2012-09-10 14:05 [Bug nptl/14568] New: Sparc64: disagreement between gdb64 and libpthread.so on where to look for %g7 ilmalakhov at yandex dot ru
` (2 preceding siblings ...)
2012-09-28 7:38 ` davem at davemloft dot net
@ 2012-09-28 7:39 ` davem at davemloft dot net
2012-10-06 5:10 ` davem at davemloft dot net
2014-06-17 4:35 ` fweimer at redhat dot com
5 siblings, 0 replies; 7+ messages in thread
From: davem at davemloft dot net @ 2012-09-28 7:39 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=14568
David S. Miller <davem at davemloft dot net> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
AssignedTo|unassigned at sourceware |davem at davemloft dot net
|dot org |
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* [Bug nptl/14568] Sparc64: disagreement between gdb64 and libpthread.so on where to look for %g7
2012-09-10 14:05 [Bug nptl/14568] New: Sparc64: disagreement between gdb64 and libpthread.so on where to look for %g7 ilmalakhov at yandex dot ru
` (3 preceding siblings ...)
2012-09-28 7:39 ` davem at davemloft dot net
@ 2012-10-06 5:10 ` davem at davemloft dot net
2014-06-17 4:35 ` fweimer at redhat dot com
5 siblings, 0 replies; 7+ messages in thread
From: davem at davemloft dot net @ 2012-10-06 5:10 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=14568
David S. Miller <davem at davemloft dot net> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
--- Comment #3 from David S. Miller <davem at davemloft dot net> 2012-10-06 05:09:43 UTC ---
[BZ #14568]
* sysdeps/sparc/tls.h (DB_THREAD_SELF_INCLUDE): Delete.
(DB_THREAD_SELF): Use constants for the register offsets. Correct
the case of a 64-bit debugger with a 32-bit inferior.
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* [Bug nptl/14568] Sparc64: disagreement between gdb64 and libpthread.so on where to look for %g7
2012-09-10 14:05 [Bug nptl/14568] New: Sparc64: disagreement between gdb64 and libpthread.so on where to look for %g7 ilmalakhov at yandex dot ru
` (4 preceding siblings ...)
2012-10-06 5:10 ` davem at davemloft dot net
@ 2014-06-17 4:35 ` fweimer at redhat dot com
5 siblings, 0 replies; 7+ messages in thread
From: fweimer at redhat dot com @ 2014-06-17 4:35 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=14568
Florian Weimer <fweimer at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Flags| |security-
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2012-09-10 14:05 [Bug nptl/14568] New: Sparc64: disagreement between gdb64 and libpthread.so on where to look for %g7 ilmalakhov at yandex dot ru
2012-09-11 8:43 ` [Bug nptl/14568] " ilmalakhov at yandex dot ru
2012-09-28 7:36 ` davem at davemloft dot net
2012-09-28 7:38 ` davem at davemloft dot net
2012-09-28 7:39 ` davem at davemloft dot net
2012-10-06 5:10 ` davem at davemloft dot net
2014-06-17 4:35 ` fweimer at redhat dot com
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