[PATCH v2] scripts/gdb: Ensure the absolute path is generated on initial source

[PATCH v2] scripts/gdb: Ensure the absolute path is generated on initial source

[Aaron Tomlin]

Post 'make scripts_gdb' a symbolic link to scripts/gdb/vmlinux-gdb.py
is created. Currently 'os.path.dirname(__file__)' does not generate
the absolute path to scripts/gdb resulting in the following:

    (gdb) source vmlinux-gdb.py
    Traceback (most recent call last):
      File "scripts/gdb/vmlinux-gdb.py", line 25, in <module>
	import linux.utils
    ModuleNotFoundError: No module named 'linux'

This patch ensures that the absolute path to scripts/gdb in relation to
the given file is generated so each module can be located accordingly.

Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
---
 scripts/gdb/vmlinux-gdb.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/gdb/vmlinux-gdb.py b/scripts/gdb/vmlinux-gdb.py
index 4136dc2c59df..3e8d3669f0ce 100644
--- a/scripts/gdb/vmlinux-gdb.py
+++ b/scripts/gdb/vmlinux-gdb.py
@@ -13,7 +13,7 @@
 
 import os
 
-sys.path.insert(0, os.path.dirname(__file__) + "/scripts/gdb")
+sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)) + "/scripts/gdb")
 
 try:
     gdb.parse_and_eval("0")
-- 
2.34.3

Re: [PATCH v2] scripts/gdb: Ensure the absolute path is generated on initial source

[Aaron Tomlin]

On Tue 2022-07-12 12:02 +0100, Aaron Tomlin wrote:
> Post 'make scripts_gdb' a symbolic link to scripts/gdb/vmlinux-gdb.py
> is created. Currently 'os.path.dirname(__file__)' does not generate
> the absolute path to scripts/gdb resulting in the following:
> 
>     (gdb) source vmlinux-gdb.py
>     Traceback (most recent call last):
>       File "scripts/gdb/vmlinux-gdb.py", line 25, in <module>
> 	import linux.utils
>     ModuleNotFoundError: No module named 'linux'
> 
> This patch ensures that the absolute path to scripts/gdb in relation to
> the given file is generated so each module can be located accordingly.
> 
> Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
> ---
>  scripts/gdb/vmlinux-gdb.py | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/scripts/gdb/vmlinux-gdb.py b/scripts/gdb/vmlinux-gdb.py
> index 4136dc2c59df..3e8d3669f0ce 100644
> --- a/scripts/gdb/vmlinux-gdb.py
> +++ b/scripts/gdb/vmlinux-gdb.py
> @@ -13,7 +13,7 @@
>  
>  import os
>  
> -sys.path.insert(0, os.path.dirname(__file__) + "/scripts/gdb")
> +sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)) + "/scripts/gdb")
>  
>  try:
>      gdb.parse_and_eval("0")
> -- 
> 2.34.3

Any feedback?


Kind regards,

-- 
Aaron Tomlin

Re: [PATCH v2] scripts/gdb: Ensure the absolute path is generated on initial source

[Doug Anderson]

Hi,

On Tue, Jul 12, 2022 at 4:03 AM Aaron Tomlin <atomlin@redhat.com> wrote:
>
> Post 'make scripts_gdb' a symbolic link to scripts/gdb/vmlinux-gdb.py
> is created. Currently 'os.path.dirname(__file__)' does not generate
> the absolute path to scripts/gdb resulting in the following:
>
>     (gdb) source vmlinux-gdb.py
>     Traceback (most recent call last):
>       File "scripts/gdb/vmlinux-gdb.py", line 25, in <module>
>         import linux.utils
>     ModuleNotFoundError: No module named 'linux'
>
> This patch ensures that the absolute path to scripts/gdb in relation to
> the given file is generated so each module can be located accordingly.
>
> Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
> ---
>  scripts/gdb/vmlinux-gdb.py | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/scripts/gdb/vmlinux-gdb.py b/scripts/gdb/vmlinux-gdb.py
> index 4136dc2c59df..3e8d3669f0ce 100644
> --- a/scripts/gdb/vmlinux-gdb.py
> +++ b/scripts/gdb/vmlinux-gdb.py
> @@ -13,7 +13,7 @@
>
>  import os
>
> -sys.path.insert(0, os.path.dirname(__file__) + "/scripts/gdb")
> +sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)) + "/scripts/gdb")

It seems to generate an absolute path for me, but some quick web
searches show that it's not guaranteed so I guess you must be hitting
whatever corner cases it ends up being relative.

The fix seems reasonable to me, thus:

Reviewed-by: Douglas Anderson <dianders@chromium.org>

Re: [PATCH v2] scripts/gdb: Ensure the absolute path is generated on initial source

[Nick Desaulniers]

On Tue, Jul 12, 2022 at 12:02:48PM +0100, Aaron Tomlin wrote:
> Post 'make scripts_gdb' a symbolic link to scripts/gdb/vmlinux-gdb.py
> is created. Currently 'os.path.dirname(__file__)' does not generate
> the absolute path to scripts/gdb resulting in the following:
> 
>     (gdb) source vmlinux-gdb.py
>     Traceback (most recent call last):
>       File "scripts/gdb/vmlinux-gdb.py", line 25, in <module>
> 	import linux.utils
>     ModuleNotFoundError: No module named 'linux'

So I recently moved to a new machine, and lost my previous .gdbinit.

I've re-added:
add-auto-load-safe-path /path/to/linux/

to my new ~/.gdbinit.

Upon startup, lx-dmesg and friends aren't available.

If I try:
(gdb) source scripts/gdb/vmlinux-gdb.py
Traceback (most recent call last):
  File "scripts/gdb/vmlinux-gdb.py", line 25, in <module>
    import linux.utils
ModuleNotFoundError: No module named 'linux'

Which is exactly the error claimed to be fixed by
commit b99695580bfc ("scripts/gdb: ensure the absolute path is generated on initial source")
even though I have b99695580bfc, which is how I found this thread to
reply to.

(gdb) show auto-load safe-path
List of directories from which it is safe to auto-load files is $debugdir:$datadir/auto-load:/path/to/linux/.

$ gdb-multiarch --version | head -n1
GNU gdb (Debian 12.1-3) 12.1
$ python3 --version
Python 3.10.8

I've also RTFM @
Documentation/dev-tools/gdb-kernel-debugging.rst
though perhaps there's something I've missed?

$ grep -rn GDB_SCRIPTS .config
4162:CONFIG_GDB_SCRIPTS=y

This definitely has worked in the past for me, on my previous
workstation.

(gdb) show configuration
...
	     --with-python=/usr (relocatable)
	     --with-python-libdir=/usr/lib (relocatable)
...
(gdb) apropos lx
(gdb)

No warnings from GDB either about the autoload path not being set.
Running gdb in my top level kernel sources.

Am I holding it wrong?

Any tips on how to go about debugging this?

> 
> This patch ensures that the absolute path to scripts/gdb in relation to
> the given file is generated so each module can be located accordingly.
> 
> Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
> ---
>  scripts/gdb/vmlinux-gdb.py | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/scripts/gdb/vmlinux-gdb.py b/scripts/gdb/vmlinux-gdb.py
> index 4136dc2c59df..3e8d3669f0ce 100644
> --- a/scripts/gdb/vmlinux-gdb.py
> +++ b/scripts/gdb/vmlinux-gdb.py
> @@ -13,7 +13,7 @@
>  
>  import os
>  
> -sys.path.insert(0, os.path.dirname(__file__) + "/scripts/gdb")
> +sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)) + "/scripts/gdb")
>  
>  try:
>      gdb.parse_and_eval("0")
> -- 
> 2.34.3
> 
> 

Re: [PATCH v2] scripts/gdb: Ensure the absolute path is generated on initial source

[Nick Desaulniers]

On Wed, Dec 14, 2022 at 10:57 AM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> On Tue, Jul 12, 2022 at 12:02:48PM +0100, Aaron Tomlin wrote:
> > Post 'make scripts_gdb' a symbolic link to scripts/gdb/vmlinux-gdb.py
> > is created. Currently 'os.path.dirname(__file__)' does not generate
> > the absolute path to scripts/gdb resulting in the following:
> >
> >     (gdb) source vmlinux-gdb.py
> >     Traceback (most recent call last):
> >       File "scripts/gdb/vmlinux-gdb.py", line 25, in <module>
> >       import linux.utils
> >     ModuleNotFoundError: No module named 'linux'
>
> So I recently moved to a new machine, and lost my previous .gdbinit.
>
> I've re-added:
> add-auto-load-safe-path /path/to/linux/
>
> to my new ~/.gdbinit.
>
> Upon startup, lx-dmesg and friends aren't available.
>
> If I try:
> (gdb) source scripts/gdb/vmlinux-gdb.py
> Traceback (most recent call last):
>   File "scripts/gdb/vmlinux-gdb.py", line 25, in <module>
>     import linux.utils
> ModuleNotFoundError: No module named 'linux'
>
> Which is exactly the error claimed to be fixed by
> commit b99695580bfc ("scripts/gdb: ensure the absolute path is generated on initial source")
> even though I have b99695580bfc, which is how I found this thread to
> reply to.
>
> (gdb) show auto-load safe-path
> List of directories from which it is safe to auto-load files is $debugdir:$datadir/auto-load:/path/to/linux/.
>
> $ gdb-multiarch --version | head -n1
> GNU gdb (Debian 12.1-3) 12.1
> $ python3 --version
> Python 3.10.8
>
> I've also RTFM @
> Documentation/dev-tools/gdb-kernel-debugging.rst
> though perhaps there's something I've missed?
>
> $ grep -rn GDB_SCRIPTS .config
> 4162:CONFIG_GDB_SCRIPTS=y
>
> This definitely has worked in the past for me, on my previous
> workstation.
>
> (gdb) show configuration
> ...
>              --with-python=/usr (relocatable)
>              --with-python-libdir=/usr/lib (relocatable)
> ...
> (gdb) apropos lx
> (gdb)
>
> No warnings from GDB either about the autoload path not being set.
> Running gdb in my top level kernel sources.
>
> Am I holding it wrong?
>
> Any tips on how to go about debugging this?

PEBKAC; looks like I was building `vmlinux` and not `all`. D'oh!

>
> >
> > This patch ensures that the absolute path to scripts/gdb in relation to
> > the given file is generated so each module can be located accordingly.
> >
> > Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
> > ---
> >  scripts/gdb/vmlinux-gdb.py | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/scripts/gdb/vmlinux-gdb.py b/scripts/gdb/vmlinux-gdb.py
> > index 4136dc2c59df..3e8d3669f0ce 100644
> > --- a/scripts/gdb/vmlinux-gdb.py
> > +++ b/scripts/gdb/vmlinux-gdb.py
> > @@ -13,7 +13,7 @@
> >
> >  import os
> >
> > -sys.path.insert(0, os.path.dirname(__file__) + "/scripts/gdb")
> > +sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)) + "/scripts/gdb")
> >
> >  try:
> >      gdb.parse_and_eval("0")
> > --
> > 2.34.3
> >
> >



-- 
Thanks,
~Nick Desaulniers