DEFINE_DYNAMIC_DEBUG_CATEGORIES(name, var, bitmap_desc, @bit_descs) allows users to define a drm.debug style (bitmap) sysfs interface, and to specify the desired mapping from bits[0-N] to the format-prefix'd pr_debug()s to be controlled.
DEFINE_DYNAMIC_DEBUG_CATEGORIES(debug_gvt, __gvt_debug, "i915/gvt bitmap desc", /** * search-prefixes, passed to dd-exec_queries * defines bits 0-N in order. * leading ^ is tacitly inserted (by callback currently) * trailing space used here excludes subcats. * helper macro needs more work * macro to autogen ++$i, 0x%x$i ? */ _DD_cat_("gvt:cmd: "), _DD_cat_("gvt:core: "), _DD_cat_("gvt:dpy: "), _DD_cat_("gvt:el: "), _DD_cat_("gvt:irq: "), _DD_cat_("gvt:mm: "), _DD_cat_("gvt:mmio: "), _DD_cat_("gvt:render: "), _DD_cat_("gvt:sched: "));
dynamic_debug.c: add 2 new elements:
- int param_set_dyndbg() - int param_get_dyndbg() - struct kernel_param_ops param_ops_dyndbg
Following the model of kernel/params.c STANDARD_PARAM_DEFS, these are non-static and exported.
get/set use an augmented kernel_param; the arg refs a new struct dyndbg_bitmap_param containing:
- the map (array, indexed by bitpos) of format-prefix strings, which define the set/category of prdbgs to be changed per each bit.
- pointer to the user's ulong holding the bits/state. by sharing state, we coordinate with code that still uses it directly
This will allow drm-debug to be converted incrementally, while still using __drm_debug & drm_debug_enabled() in other parts.
param_set_dyndbg() compares new vs old bits, and only updates prdbgs on changes. This maximally preserves the underlying state, which may have been customized via later `echo $cmd >control`. So if a user really wants to know that all prdbgs are set precisely, they must pre-clear then set.
TLDR: this also doesn't affect the decorator flags "mflt" set per prdbg.
dynamic_debug.h:
Add DEFINE_DYNAMIC_DEBUG_CATEGORIES() described above, and a stub throwing a BUILD_BUG (RFC) when used without DYNAMIC_DEBUG support. Add structs dyndbg_bitdesc, dyndbg_bitmap_param to support the macro.
Note that it also calls MODULE_PARM_DESC for the user, but expects the user to catenate all the bit-descriptions together (as is done in drm.debug), and in the following uses in amdgpu, i915.
The intent is to regenerate this output from per-bit help given in VA_ARGS, including a bit_label(); but this can wait.
Also externs the struct kernel_param param_ops_dyndbg symbol, as is done in moduleparams.h for all the STANDARD params.
USAGE NOTES:
Using dyndbg to query on "format ^$prefix" requires that the prefix be present in the compiled-in format string; where run-time prefixing is used, that format would be "%s...", which is not usefully selectable.
Using DEFINE_DYNAMIC_DEBUG_CATEGORIES wo support gets a BUILD_BUG. ISTM there is already action at a declarative distance, nobody needs mystery as to why the /sysfs thingy didn't appear.
Dyndbg is completely agnostic wrt the categorization scheme used, in order to play well with any prefix convention already in use in the codebase. Ad-hoc categories and sub-categories are implicitly allowed, author discipline and review is expected.
Here are some examples:
"1","2","3" 2 doesn't imply 1. otherwize, sorta like printk levels "1:","2:","3:" are better, avoiding [1-9]\d+ ambiguity "hi:","mid:","low:" are reasonable, and imply independence "todo:","rfc:","fixme:" might be handy "A:".."Z:" uhm, yeah
Hierarchical classes/categories are natural:
"drm:<CAT>:" is used in a later commit "drm:<CAT>:<SUB>:" is a natural extension. "drm:atomic:fail:" has been proposed, sounds directly useful
NB: in a real sense we abandon enum strictures here, and lose some compiler help, on spelling errs for example. Obviously "drm:" != "DRM:".
Some properties of a hierarchical category deserve explication:
Trailing spaces matter !
With 1..3-space ("drm: ", "drm:atomic: ", "drm:atomic:fail: "), the ":" doesn't terminate the search-space, the trailing space does. So a "drm:" search spec will match all DRM categories & subcategories, and will not be useful in an interface where all categories are already controlled together. That said, "drm:atomic:" & "drm:atomic: " are different, and both are useful in cases.
Ad-Hoc sub-categories:
These have a caveat wrt wrapper macros adding prefixes like "drm:atomic: "; the trailing space in the prefix means that drm_dbg_atomic("fail: ...") pastes as "drm:atomic: fail: ", which obviously isn't ideal wrt clear and simple bitmaps.
A possible solution is to have a FOO_() version of every FOO() macro which (anti-mnemonically) elides the trailing space, which is normally inserted by a newer FOO().
IE: drm_dbg_atomic_("fail: ..."); // trailing _ means ad-hoc subcat
Summarizing:
- "drm:kms: " & "drm:kms:" are different - "drm:kms" also different - includes drm:kms2: - "drm:kms:\t" also different - could be troublesome - "drm:kms:*" doesn't work, no wildcard on format atm.
Order matters in DEFINE_DYNAMIC_DEBUG_CATEGORIES(... @bit_descs)
@bit_descs (array) position determines the bit mapping to the prefix, so to keep a stable map, new categories or 3rd level categories must be added to the end.
Since bits are/will-stay applied 0-N, the later bits can countermand the earlier ones, but it's tricky - consider;
DD_CATs(... "drm:atomic:", "drm:atomic:fail:" ) // misleading
The 1st search-term is misleading, because it includes (modifies) subcategories, but then 2nd overrides it. So don't do that.
Signed-off-by: Jim Cromie jim.cromie@gmail.com --- v5: . rename to DEFINE_DYNAMIC_DEBUG_CATEGORIES from DEFINE_DYNDBG_BITMAP . in set_dyndbg, replace hardcoded "i915" w kp->mod->name . static inline the stubs . const *str in structs, const array. - Emil . dyndbg: add do-nothing DEFINE_DYNAMIC_DEBUG_CATEGORIES if !DD_CORE . call MOD_PARM_DESC(name, "$desc") for users . simplify callback, remove bit-change detection . config errs reported by lkp@intel.com
v6: . return rc, bitmap->, snprintf, ws - Andy Shevchenko . s/chgct/matches/ - old varname is misleading . move code off file bottom to a "better" place . change ##fsname to ##var for less generic varname (ie: not "debug") . add KP_MOD_NAME workaround for !CONFIG_MODULES . move forward decl down to where its needed
v7: . use kp->arg, dont need kp->data or previous patch-1 - jbaron . use client's ulong for bits, share state . throw BUILD_BUG if DEFINE_DYNAMIC_DEBUG_CATEGORIES used wo support --- include/linux/dynamic_debug.h | 60 ++++++++++++++++++++++++++ lib/dynamic_debug.c | 79 ++++++++++++++++++++++++++++++++++- 2 files changed, 138 insertions(+), 1 deletion(-)
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h index dce631e678dd..f51b738668a0 100644 --- a/include/linux/dynamic_debug.h +++ b/include/linux/dynamic_debug.h @@ -181,6 +181,10 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor, KERN_DEBUG, prefix_str, prefix_type, \ rowsize, groupsize, buf, len, ascii)
+struct kernel_param; +int param_set_dyndbg(const char *instr, const struct kernel_param *kp); +int param_get_dyndbg(char *buffer, const struct kernel_param *kp); + #else /* !CONFIG_DYNAMIC_DEBUG_CORE */
#include <linux/string.h> @@ -227,6 +231,62 @@ static inline int dynamic_debug_exec_queries(const char *query, const char *modn return 0; }
+struct kernel_param; +static inline int param_set_dyndbg(const char *instr, const struct kernel_param *kp) +{ return 0; } +static inline int param_get_dyndbg(char *buffer, const struct kernel_param *kp) +{ return 0; } + #endif /* !CONFIG_DYNAMIC_DEBUG_CORE */
+struct dyndbg_bitdesc { + /* bitpos is inferred from index in containing array */ + const char *prefix; + const char *help; +}; + +struct dyndbg_bitmap_param { + unsigned long *bits; + struct dyndbg_bitdesc map[]; +}; + +#if defined(CONFIG_DYNAMIC_DEBUG) || \ + (defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE)) +/** + * DEFINE_DYNAMIC_DEBUG_CATEGORIES() - bitmap control of categorized prdbgs + * @fsname: parameter basename under /sys + * @var: C-identifier holding bitmap + * @_desc: string summarizing the controls provided + * @...: list of struct dyndbg_bitdesc initializations + * + * Intended for modules with substantial use of "categorized" prdbgs + * (those with some systematic prefix in the format string), this lets + * modules (using dyndbg) control those prdbg groups according to + * their prefixes, and map them to bits 0-N of a sysfs control point. + * The @bits... identifies the prefixes to be used by dyndbg to + * select and alter those categorized prdbgs, order defines bitpos. + */ +#define DEFINE_DYNAMIC_DEBUG_CATEGORIES(fsname, _var, _desc, ...) \ + MODULE_PARM_DESC(fsname, _desc); \ + static struct dyndbg_bitmap_param ddcats_##_var = \ + { .bits = &_var, .map = { __VA_ARGS__, { .prefix = NULL }}}; \ + module_param_cb(fsname, ¶m_ops_dyndbg, &ddcats_##_var, 0644) + +#define _DD_cat_(pfx) { .prefix = pfx, .help = "help for " pfx } +#define _DD_cat_help_(pfx) "\t " pfx "\t- help for " pfx "\n" + +extern const struct kernel_param_ops param_ops_dyndbg; + +#elif (defined(CONFIG_DYNAMIC_DEBUG_CORE) && !defined(DYNAMIC_DEBUG_MODULE)) + +#define DEFINE_DYNAMIC_DEBUG_CATEGORIES(fsname, var, bitmap_desc, ...) \ + BUILD_BUG_ON_MSG(1, "you need -DDYNAMIC_DEBUG_MODULE in compile") + +#else +#define DEFINE_DYNAMIC_DEBUG_CATEGORIES(fsname, var, bitmap_desc, ...) \ + BUILD_BUG_ON_MSG(1, "DYNAMIC_DEBUG support required to use this macro: " #var) +#define _DD_cat_(pfx) +#define _DD_cat_help_(pfx) +#endif + #endif diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index cb5abb42c16a..9f9e70023aa4 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -529,7 +529,7 @@ static int ddebug_exec_queries(char *query, const char *modname) if (!query || !*query || *query == '#') continue;
- vpr_info("query %d: "%s"\n", i, query); + vpr_info("query %d: "%s" mod:%s\n", i, query, modname ?: "*");
rc = ddebug_exec_query(query, modname); if (rc < 0) { @@ -577,6 +577,83 @@ int dynamic_debug_exec_queries(const char *query, const char *modname) } EXPORT_SYMBOL_GPL(dynamic_debug_exec_queries);
+#ifdef CONFIG_MODULES +#define KP_MOD_NAME kp->mod->name +#else +#define KP_MOD_NAME NULL /* wildcard */ +#endif +#define FMT_QUERY_SIZE 128 /* typically need <40 */ +/** + * param_set_dyndbg - bits => categories >control setter + * @instr: string echo>d to sysfs + * @kp: kp->arg has state: bits, map + * + * Enable/disable prdbgs by their "category", as defined in args to + * DEFINE_DYNAMIC_DEBUG_CATEGORIES + * Returns: 0 or <0 if error. + */ +int param_set_dyndbg(const char *instr, const struct kernel_param *kp) +{ + unsigned long inbits; + int rc, i, matches = 0, totct = 0; + char query[FMT_QUERY_SIZE]; + const struct dyndbg_bitmap_param *p = kp->arg; + const struct dyndbg_bitdesc *map = p->map; + + if (!map) { + pr_err("set_dyndbg: no bits=>queries map\n"); + return -EINVAL; + } + rc = kstrtoul(instr, 0, &inbits); + if (rc) { + pr_err("set_dyndbg: failed\n"); + return rc; + } + vpr_info("set_dyndbg: new 0x%lx old 0x%lx\n", inbits, *p->bits); + + for (i = 0; map->prefix && i < BITS_PER_LONG; map++, i++) { + + if (test_bit(i, &inbits) == test_bit(i, p->bits)) + continue; + snprintf(query, FMT_QUERY_SIZE, "format '^%s' %cp", map->prefix, + test_bit(i, &inbits) ? '+' : '-'); + + matches = ddebug_exec_queries(query, KP_MOD_NAME); + + v2pr_info("bit-%d: %d matches on format '^%s'\n", i, + matches, map->prefix); + totct += matches; + } + *p->bits = inbits; + vpr_info("total matches: %d\n", totct); + return 0; +} +EXPORT_SYMBOL(param_set_dyndbg); + +/** + * param_get_dyndbg - bitmap reader + * @buffer: receives string rep of bitmap + * @kp: kp->arg has state: bits, map + * + * Reads last written bits, underlying prdbg state may have changed since. + * Returns: #chars written + */ +int param_get_dyndbg(char *buffer, const struct kernel_param *kp) +{ + const struct dyndbg_bitmap_param *p = kp->arg; + unsigned long val = *p->bits; + + return scnprintf(buffer, PAGE_SIZE, "0x%lx\n", val); +} +EXPORT_SYMBOL(param_get_dyndbg); + +const struct kernel_param_ops param_ops_dyndbg = { + .set = param_set_dyndbg, + .get = param_get_dyndbg, +}; +/* support DEFINE_DYNAMIC_DEBUG_CATEGORIES users */ +EXPORT_SYMBOL(param_ops_dyndbg); + #define PREFIX_SIZE 64
static int remaining(int wrote)