commit 7b1ae24827 upstream.
Query like 'file tcp_input.c line 1234 +p' was broken by
commit aaebe329bf ("dyndbg: accept 'file foo.c:func1' and 'file
foo.c:10-100'") because a file name without a ':' now makes the loop in
ddebug_parse_query() exits early before parsing the 'line 1234' part.
As a result, all pr_debug() in tcp_input.c will be enabled, instead of only
the one on line 1234. Changing 'break' to 'continue' fixes this.
Fixes: aaebe329bf ("dyndbg: accept 'file foo.c:func1' and 'file foo.c:10-100'")
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Shuo Chen <shuochen@google.com>
Acked-by: Jason Baron <jbaron@akamai.com>
Link: https://lore.kernel.org/r/20210414212400.2927281-1-giantchen@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 42f07816ac as it
still causes problems. It will be resolved later, let's revert it so we
can also revert the original patch this was supposed to be helping with.
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Fixes: 42f07816ac ("dyndbg: fix problem parsing format="foo bar"")
Cc: Jim Cromie <jim.cromie@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 14775b0496 ("dyndbg: accept query terms like file=bar and
module=foo") added the combined keyword=value parsing poorly; revert
most of it, keeping the keyword & arg change.
Instead, fix the tokenizer for the new input, by terminating the
keyword (an unquoted word) on '=' as well as space, thus letting the
tokenizer work on the quoted argument, like it would have previously.
Also add a few debug-prints to show more parsing context, into
tokenizer and parse-query, and use "keyword, value" in others.
Fixes: 14775b0496 ("dyndbg: accept query terms like file=bar and module=foo")
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200831182210.850852-4-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 4c0d77828d ("dyndbg: export ddebug_exec_queries") had a few
problems:
- broken non DYNAMIC_DEBUG_CORE configs, sparse warning
- the exported function modifies query string, breaks on RO strings.
- func name follows internal convention, shouldn't be exposed as is.
1st is fixed in header with ifdefd function prototype or stub defn.
Also remove an obsolete HAVE-symbol ifdef-comment, and add others.
Fix others by wrapping existing internal function with a new one,
named in accordance with module-prefix naming convention, before
export hits v5.9.0. In new function, copy query string to a local
buffer, so users can pass hard-coded/RO queries, and internal function
can be used unchanged.
Fixes: 4c0d77828d ("dyndbg: export ddebug_exec_queries")
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200831182210.850852-3-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Export ddebug_exec_queries() for use by modules.
This will allow module authors to control all their *pr_debug*s
dynamically. And since ddebug_exec_queries() is what implements
"echo $query >control", it gives the same per-callsite control.
Virtues of this:
- simplicity. just an export.
- full control over any/all subsets of callsites.
- same "query/command-string" in code and console
- full callsite selectivity with module file line format
Format in particular deserves special attention; it is where
low-hanging fruit will be found.
Consider: drivers/gpu/drm/amd/display/include/logger_types.h:
#define DC_LOG_SURFACE(...) pr_debug("[SURFACE]:"__VA_ARGS__)
#define DC_LOG_HW_LINK_TRAINING(...) pr_debug("[HW_LINK_TRAINING]:"__VA_ARGS__)
.. 9 more ..
Thats 11 string prefixes, used in 804 places in drivers/gpu/**
Clearly this is a systematized classification of those callsites.
And one I'd expect to see repeated often.
Using ddebug_exec_queries(), authors can select on those prefixes
as a unitary set, equivalent to:
echo "module=MODULE_NAME format=^[SURFACE]: +p" >control
Trivially, those sets can be subsected with the other query terms too,
say file=foo, should the author see fit.
Perhaps as important, users can modify the set of enabled callsites,
presumably to aid debugging by enabling helpful debug callsites, and
disabling those that just clutter the info.
Authors could even alter [fmlt] flags, though I dont see a good reason
why they would. Perhaps harnessed by bug-logging automation to get
fuller, or more minimal bug-reports.
DRM
drm has both drm.debug, which defines 32 categories of drm_printk
logging, and entirely separate uses of pr_debug, which are dynamic on
this i915 laptop, running mainline. So I can observe and report on
both.
The i915 driver has 118 dyndbg callsites, with following
"classifications" defined in drivers/gpu/drm/i915/gvt/**
$ grep 915 /proc/dynamic_debug/control | cut -d= -f2 | cut -d: -f1,2 | sort -u
_ "gvt: cmd
_ "gvt: core
_ "gvt: dpy
_ "gvt: el
_ "gvt: irq
_ "gvt: mm
_ "gvt: mmio
_ "gvt: render
_ "gvt: sched
_ "%s for root hub!\012"
_ "Vendor defined info completion code %u\012"
This classification is entirely out-of-band for control by drm.debug,
and is only available to root user at the console. But module authors
can activate them with ddebug_exec_queries(sprintf("format=^%s +p")),
and then decide how to expose the groups to the user for max utility.
drm.debug
drm.debug has 32 bit-flags, and matching enum drm_debug_category
values to classify the ~2943 DRM_DEBUG*() callsites in drivers/gpu
The drm.debug callback could invoke ddebug_exec_queries() with 32
different hardcoded query strings, needing only (bit) ? " +p" : " -p"
added.
I briefly enabled drm.debug=0xff on my i915 laptop, which yielded
these unique prefixes: (dmesg | cut -c17- | cut -d\] -f1 | sort -u)
[drm:drm_atomic_check_only [drm
[drm:drm_atomic_get_crtc_state [drm
[drm:drm_atomic_get_plane_state [drm
[drm:drm_atomic_nonblocking_commit [drm
[drm:drm_atomic_set_fb_for_plane [drm
[drm:drm_atomic_state_default_clear [drm
[drm:__drm_atomic_state_free [drm
[drm:drm_atomic_state_init [drm
[drm:drm_crtc_vblank_helper_get_vblank_timestamp_internal [drm
[drm:drm_handle_vblank [drm
[drm:drm_ioctl [drm
[drm:drm_mode_addfb2 [drm
[drm:drm_mode_object_get [drm
[drm:drm_mode_object_put.part.0 [drm
[drm:drm_update_vblank_count [drm
[drm:drm_vblank_enable [drm
[drm:drm_vblank_restore [drm
[drm:vblank_disable_fn [drm
i915 0000:00:02.0: [drm:gen9_set_dc_state [i915
i915 0000:00:02.0: [drm:intel_atomic_get_global_obj_state [i915
i915 0000:00:02.0: [drm:__intel_display_power_get_domain.part.0 [i915
i915 0000:00:02.0: [drm:__intel_display_power_put_domain [i915
i915 0000:00:02.0: [drm:intel_plane_atomic_calc_changes [i915
i915 0000:00:02.0: [drm:skl_enable_dc6 [i915
Several good format=^prefixes are apparent there, and some misses.
^[drm:drm_atomic_ # misses: [drm:__drm_atomic_state_free [drm
^[drm:drm_ioctl
^[drm:drm_mode
^[drm:drm_vblank_ # misses: [drm:drm_update_vblank_count & [drm:vblank_disable_fn
Its not a perfect 1:1 single format-match per class, but the misses
above can be covered with 1 & 2 additional queries, which can be
concatenated together with ";" separators and submitted with 1 call.
Benefits:
For drm, adapting DRM_DEBUG to use dynamic-debug inside could
replicate (and thereby obsolete) lots of bit-checking in current
DRM_DEBUG callsites, at least with JUMP_LABEL optimized code.
ddebug_exec_queries() and a handful of fixed query-strings can select
and thereby control the already classified callsites.
With the classes mapped to queries, the enum type and parameter can be
eliminated (folded away with macro magic), at least for DYNAMIC_DEBUG
& JUMP_LABEL builds.
Is it safe ?
ddebug_exec_queries() is currently exposed to user space in
several limited ways;
1 it is called from module-load callback, where it implements the
$modname.dyndbg=+p "fake" parameter provided to all modules.
2 it handles query input via >control directly
IOW, it is "fully" exposed to local root user; exposing the same
functionality to other kernel modules is no additional risk.
The other standard issue to check is locking:
dyndbg has a single mutex, taken by ddebug_change to handle >control,
and by ddebug_proc_(start|stop) to span `cat control`. Queries
submitted via export will typically have module specified, which
dramatically cuts the scan by ddebug_change vs "module=* +p".
ISTM this proposed export presents no locking problems.
TLDR;
It would be interesting to see how drm.dyndbg=$QUERY and
drm.debug=$HEXY would interact; it might be order dependent, as
if given as modprobe args or in /etc/modprobe.d/
Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-19-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This should work:
echo module=amd* format=^[IF_TRACE]: +p >/proc/dynamic_debug/control
consider drivers/gpu/drm/amd/display/include/logger_types.h:
It has 11 defines like:
#define DC_LOG_IF_TRACE(...) pr_debug("[IF_TRACE]:"__VA_ARGS__)
These defines are used 804 times at recent count; they are a good use
case to evaluate existing format-message based classifications of
*pr_debug*. Those macros prefix the supplied format with a fixed
string, I'd expect most existing message classification schemes to do
something similar.
Hence we want to be able to anchor our match to the beginning of the
format string, allowing easy construction of clear and precise
queries, leveraging the existing classification scheme to enable and
disable those callsites.
Note that unlike other search terms, formats are implicitly floating
substring matches, without the need for explicit wildcards.
This makes no attempt at wider regex features, just the one we need.
TLDR: Using the anchor also means the []s are less helpful for
disamiguating the prefix from a random in-message occurrence, allowing
shorter prefixes.
Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-17-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
flags & mask are used together everywhere, and are passed around
together between multiple functions; they belong together in a struct,
call that struct flag_settings.
Use struct flag_settings to rework 3 functions:
- ddebug_exec_query - declares query and flag-settings,
calls other 2, passing flags
- ddebug_parse_flags - fills flag_settings and returns
- ddebug_change - test all callsites against query,
modify passing sites.
benefits:
- bit-banging always needs flags & mask, best together.
- simpler function signatures
- 1 less parameter, less stack overhead
no functional changes
Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-16-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Accept these additional query forms:
echo "file $filestr +_" > control
path/to/file.c:100 # as from control, column 1
path/to/file.c:1-100 # or any legal line-range
path/to/file.c:func_A # as from an editor/browser
path/to/file.c:drm_* # wildcards still work
path/to/file.c:*_foo # lead wildcard too
1st 2 examples are treated as line-ranges, 3-5 are treated as func's
Doc these changes, and sprinkle in a few extra wild-card examples and
trailing # explanation texts.
Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-14-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ddebug_describe_flags() currently fills a caller provided string buffer,
after testing its size (also passed) in a BUG_ON. Fix this by
replacing them with a known-big-enough string buffer wrapped in a
struct, and passing that instead.
Also simplify ddebug_describe_flags() flags parameter from a struct to
a member in that struct, and hoist the member deref up to the caller.
This makes the function reusable (soon) where flags are unpacked.
Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-8-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
during dyndbg init, verbose logging prints its ram overhead. It
counted strlens of struct _ddebug's 4 string members, in all callsite
entries, which would be approximately correct if each had been
mallocd. But they are pointers into shared .rodata; for example, all
10 kobject callsites have identical filename, module values.
Its best not to count that memory at all, since we cannot know they
were linked in because of CONFIG_DYNAMIC_DEBUG=y, and we want to
report a number that reflects what ram is saved by deconfiguring it.
Also fix wording and size under-reporting of the __dyndbg section.
Heres my overhead, on a virtme-run VM on a fedora-31 laptop:
dynamic_debug:dynamic_debug_init: 260 modules, 2479 entries \
and 10400 bytes in ddebug tables, 138824 bytes in __dyndbg section
Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-7-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The verbose/debug logging done for `cat $MNT/dynamic_debug/control` is
voluminous (2 per control file entry + 2 per PAGE). Moreover, it just
prints pointer and sequence, which is not useful to a dyndbg user.
So just drop them.
Also require verbose>=2 for several other debug printks that are a bit
too chatty for typical needs;
ddebug_change() prints changes, once per modified callsite. Since
queries like "+p" will enable ~2300 callsites in a typical laptop, a
user probably doesn't need to see them often. ddebug_exec_queries()
still summarizes with verbose=1.
ddebug_(add|remove)_module() also print 1 line per action on a module,
not needed by typical modprobe user.
This leaves verbose=1 better focussed on the >control parsing process.
Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-5-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
