[Bug gdb/12953] New: No hardware watchpoints on FreeBSD md64

[Bug gdb/12953] New: No hardware watchpoints on FreeBSD md64

[yuri at tsoft dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12953

           Summary: No hardware watchpoints on FreeBSD md64
           Product: gdb
           Version: 7.2
            Status: NEW
          Severity: normal
          Priority: P2
         Component: gdb
        AssignedTo: unassigned@sourceware.org
        ReportedBy: yuri@tsoft.com


When I set a watchpoint they came out software, not hardware.

This causes waste of time while waiting for software watchpoint to be
triggered.
gdb should default to hardware watchpoints and should print an explanation why
it can't be set in case it can't.

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[Bug gdb/12953] No hardware watchpoints on FreeBSD amd64

[yuri at tsoft dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12953

yuri at tsoft dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|No hardware watchpoints on  |No hardware watchpoints on
                   |FreeBSD md64                |FreeBSD amd64

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[Bug gdb/12953] No hardware watchpoints on FreeBSD amd64

[yuri at tsoft dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12953

--- Comment #1 from yuri at tsoft dot com 2011-07-01 00:47:53 UTC ---
I used this C++ program:
#include <string.h>

void ms(char *p) {
  memset(p, 0, 1024);
}

main() {
  char buf1[1024];
  buf1[256] = 7;
  ms(buf1);
}

gdb_7_3-branch.

In the log below you can see that it has set 'Watchpoint', not 'Hardware
watchpoint'.

---- gdb session log ----
[yuri@mybsd ~/gdb]$ gdb ./main
GNU gdb (GDB) 7.2.90.20110630-cvs
Copyright (C) 2011 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-unknown-freebsd8.2".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /usr/home/yuri/gdb/main...done.
(gdb) b main
Breakpoint 1 at 0x40065b: file main.C, line 9.
(gdb) r
Starting program: /usr/home/yuri/gdb/main

Breakpoint 1, main () at main.C:9
9         buf1[256] = 7;
(gdb) n
10        ms(buf1);
(gdb) p &buf1[256]
$1 = 0x7fffffffddd0 "\a"
(gdb) watch *(char*)0x7fffffffddd0
Watchpoint 2: *(char*)0x7fffffffddd0
(gdb) c
Continuing.
Watchpoint 2: *(char*)0x7fffffffddd0

Old value = 7 '\a'
New value = 0 '\000'
0x0000000800b78074 in memset () from /lib/libc.so.7
(gdb) c
Continuing.
Watchpoint 2: *(char*)0x7fffffffddd0

Old value = 0 '\000'
New value = 1 '\001'
0x0000000800505c6c in ?? () from /libexec/ld-elf.so.1
(gdb) r
The program being debugged has been started already.
Start it from the beginning? (y or n) y
Starting program: /usr/home/yuri/gdb/main
^C
Program received signal SIGINT, Interrupt.
0x0000000800505959 in ?? () from /libexec/ld-elf.so.1
(gdb) quit
A debugging session is active.

        Inferior 1 [process 49302] will be killed.

Quit anyway? (y or n) y

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[Bug gdb/12953] No hardware watchpoints on FreeBSD amd64

[valery.khromov at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12953

Valery Khromov <valery.khromov at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |valery.khromov at gmail dot
                   |                            |com

--- Comment #2 from Valery Khromov <valery.khromov at gmail dot com> 2011-12-04 21:19:46 UTC ---
See patch http://sourceware.org/bugzilla/attachment.cgi?id=6088&action=diff

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[Bug gdb/12953] No hardware watchpoints on FreeBSD amd64

[yuri at tsoft dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12953

yuri at tsoft dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|7.2                         |7.3

--- Comment #3 from yuri at tsoft dot com 2011-12-04 23:30:43 UTC ---
I tried the patch (with 7.3.1) and it didn't work.

Patch applied, and gdb compiled.
gdb now says it does set Hardware watchpoints.
But gdb didn't stop when the memory value actually changed.

8.2-STABLE amd64

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[Bug gdb/12953] No hardware watchpoints on FreeBSD amd64

[valery.khromov at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12953

--- Comment #4 from Valery Khromov <valery.khromov at gmail dot com> 2011-12-05 00:42:48 UTC ---
Created attachment 6089
  --> http://sourceware.org/bugzilla/attachment.cgi?id=6089
Updated patch

Attached updated patch fixes watching local variables.


However, it looks like gdb isn't able to watch uninitialized variables:

$ cat main.c 
#include <string.h>

void ms(char *p) {
  memset(p, 0, 1024);
}

main() {
#ifdef INIT_BUF1
  char buf1[1024] = { 0 };
#else
  char buf1[1024];
#endif
  buf1[256] = 7;
  ms(buf1);
}

$ cc main.c -ggdb -O0 -o main-notinit

$ cc main.c -ggdb -O0 -DINIT_BUF1 -o main-init


$ gdb main-notinit              
GNU gdb (GDB) 7.3.1 [GDB v7.3.1 for FreeBSD]
Copyright (C) 2011 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-portbld-freebsd8.2".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from
/place/home/qwerty/gdb-freebsd-fixes/tst/main-notinit...done.
(gdb) br main
Breakpoint 1 at 0x4005ab: file main.c, line 13.
(gdb) r
Starting program: /place/home/qwerty/gdb-freebsd-fixes/tst/main-notinit 

Breakpoint 1, main () at main.c:13
13      buf1[256] = 7;
(gdb) wa buf1[256]
Hardware watchpoint 2: buf1[256]
(gdb) c
Continuing.

Watchpoint 2 deleted because the program has left the block in
which its expression is valid.
0x00000000004004ee in _start ()


$ gdb main-init   
GNU gdb (GDB) 7.3.1 [GDB v7.3.1 for FreeBSD]
Copyright (C) 2011 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-portbld-freebsd8.2".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /place/home/qwerty/gdb-freebsd-fixes/tst/main-init...done.
(gdb) br main
Breakpoint 1 at 0x4005ab: file main.c, line 9.
(gdb) r
Starting program: /place/home/qwerty/gdb-freebsd-fixes/tst/main-init 

Breakpoint 1, main () at main.c:9
9      char buf1[1024] = { 0 };
(gdb) wa buf1[256]
Hardware watchpoint 2: buf1[256]
(gdb) c
Continuing.
Hardware watchpoint 2: buf1[256]

Old value = 0 '\000'
New value = 7 '\a'
main () at main.c:14
14      ms(buf1);
(gdb) 
Continuing.
Hardware watchpoint 2: buf1[256]

Old value = 7 '\a'
New value = 0 '\000'
0x000000003273b1c4 in memset () from /lib/libc.so.7
(gdb) 
Continuing.

Watchpoint 2 deleted because the program has left the block in
which its expression is valid.
0x00000000004004ee in _start ()



I tested it on Linux with the similar result: the watchpoint is triggered on
the second variable change by memset, not on the first assignment:

$ gdb main-notinit
GNU gdb (GDB) 7.0-debian
Copyright (C) 2009 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /tmp/ll/main-notinit...done.
(gdb) br main
Breakpoint 1 at 0x400518: file main.c, line 13.
(gdb) r
Starting program: /tmp/ll/main-notinit 

Breakpoint 1, main () at main.c:13
13      buf1[256] = 7;
(gdb) wa buf1[256]
Hardware watchpoint 2: buf1[256]
(gdb) c
Continuing.
Hardware watchpoint 2: buf1[256]

Old value = -16 '\360'
New value = 0 '\000'
memset () at ../sysdeps/x86_64/memset.S:1017
1017    ../sysdeps/x86_64/memset.S: No such file or directory.
    in ../sysdeps/x86_64/memset.S
Current language:  auto
The current source language is "auto; currently asm".

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[Bug gdb/12953] No hardware watchpoints on FreeBSD amd64

[yuri at tsoft dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12953

--- Comment #5 from yuri at tsoft dot com 2011-12-05 01:13:43 UTC ---
The latest patch works. Thanks!

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[Bug gdb/12953] No hardware watchpoints on FreeBSD amd64

[valery.khromov at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12953

Valery Khromov <valery.khromov at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |nge at cs dot hmc.edu

--- Comment #6 from Valery Khromov <valery.khromov at gmail dot com> 2011-12-05 01:19:10 UTC ---
*** Bug 9118 has been marked as a duplicate of this bug. ***

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[Bug gdb/12953] No hardware watchpoints on FreeBSD amd64

[tromey at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12953

Tom Tromey <tromey at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tromey at redhat dot com

--- Comment #7 from Tom Tromey <tromey at redhat dot com> 2011-12-05 21:29:24 UTC ---
The best thing to do now is follow the contribution instructions:
http://sourceware.org/gdb/contribute/

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[Bug gdb/12953] No hardware watchpoints on FreeBSD amd64

[valery.khromov at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12953

--- Comment #8 from Valery Khromov <valery.khromov at gmail dot com> 2011-12-06 19:09:02 UTC ---
I have sent an e-mail with the patch to gdb-patches@
Tom, could you please review it?

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[Bug gdb/12953] No hardware watchpoints on FreeBSD amd64

[cvs-commit at gcc dot gnu.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=12953

--- Comment #9 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> 2012-02-09 16:06:51 UTC ---
CVSROOT:    /cvs/src
Module name:    src
Changes by:    palves@sourceware.org    2012-02-09 16:06:44

Modified files:
    gdb            : ChangeLog Makefile.in amd64bsd-nat.c 
                     amd64fbsd-nat.c 
    gdb/config/i386: fbsd64.mh 
Added files:
    gdb            : amd64bsd-nat.h 

Log message:
    2012-02-09  Valery Khromov  <valery.khromov@gmail.com>

    PR gdb/12953
    * Makefile.in (HFILES_NO_SRCDIR): Add amd64bsd-nat.h.
    * amd64bsd-nat.c: Add support for debug registers (adapted from
    i386bsd-nat.c).
    [HAVE_PT_GETDBREGS] (amd64bsd_dr_get, amd64bsd_dr_set)
    (amd64bsd_dr_set_control, amd64bsd_dr_set_addr)
    (amd64bsd_dr_get_addr, amd64bsd_dr_get_status)
    (amd64bsd_dr_get_control): New functions.
    * amd64bsd-nat.h: New file (adapted from i386bsd-nat.h).
    * amd64fbsd-nat.c: Include "amd64bsd-nat.h", "i386-nat.h".
    [HAVE_PT_GETDBREGS] (_initialize_amd64fbsd_nat): Add hardware
    watchpoints initialization.
    * config/i386/fbsd64.mh (NATDEPFILES): Add i386-nat.o.

Patches:
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/amd64bsd-nat.h.diff?cvsroot=src&r1=NONE&r2=1.1
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/ChangeLog.diff?cvsroot=src&r1=1.13818&r2=1.13819
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/Makefile.in.diff?cvsroot=src&r1=1.1187&r2=1.1188
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/amd64bsd-nat.c.diff?cvsroot=src&r1=1.19&r2=1.20
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/amd64fbsd-nat.c.diff?cvsroot=src&r1=1.28&r2=1.29
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/config/i386/fbsd64.mh.diff?cvsroot=src&r1=1.12&r2=1.13

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[Bug gdb/12953] No hardware watchpoints on FreeBSD amd64

[palves at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12953

Pedro Alves <palves at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |palves at redhat dot com
         Resolution|                            |FIXED
   Target Milestone|---                         |7.5

--- Comment #10 from Pedro Alves <palves at redhat dot com> 2012-02-09 16:12:00 UTC ---
Patch checked in.  Thank you.

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