DEFINE_DYNAMIC_DEBUG_CLASSBITS(fsname, var, bitmap_desc, classes..) allows users to create a drm.debug style (bitmap) sysfs interface, to control sets of pr_debug's according to their .class_id's
This wraps existing "class" keyword and behavior:
bash-5.1# echo <<END > /proc/dynamic_debug/control
module drm class 0 +p module drm class 2 +p END
With the macro used (in a client), this is basically equivalent:
# but this also clears other flags, if theyre set echo 0x05 > /sys/module/drm/parameters/debug
To use:
DEFINE_DYNAMIC_DEBUG_CLASSBITS(debug, __drm_debug, "pmfl", "drm.debug - bits => categories:", /* vector of uint:4 symbols, ala enum drm_debug_category, 15 is EOL */ DRM_UT_CORE, DRM_UT_DRIVER, DRM_UT_KMS ... );
The 3rd arg is a string with any of the dyndbg.flags [pmflt_]+ Full exposure of the flags here lets the module author:
- fully customize/take-over the decorations of enabled sites. generally leaving decorations to user is preferred.
- aim the debug-stream: now printk, later tracefs. using both together means more work (p or T, in practice) iface doesn't care about new flags added later
- declare 2 separate sysfs-knobs, one each for p, T, if desired.
- decorations are per callsite, shared across sysfs-knobs for any controlled classes
To support the macro, the patch adds:
- int param_set_dyndbg_classbits() - int param_get_dyndbg_classbits() - struct kernel_param_ops param_ops_dyndbg_classbits
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:
A- the vector of classes (drm.debug "categories") being controlled
This in-line vector of constants (uint [0-14]) specifies a sequence of controlling bits (by position, starting at 0) with the values naming the class_id's mapped to that bit.
A value of _DPRINTK_SITE_UNCLASSED terminates the vector processing by param_set_dyndbg_classbits(), and is appended by the macro to insure a defined termination after max 15 classes are applied.
Technically, the vector is a flex-array, but its size is practically limited to max 15 in length (repeats are pointless).
B- a pointer to the user module's ulong holding the bits/state.
By accessing client's bit-state, we coordinate with existing code that still uses drm_debug_enabled(), so they work unchanged. The change to ulong allows use of BIT() etc.
NOTES:
_DPRINTK_SITE_UNCLASSED = 15, ie 2**CLS_BITS-1, deserves special mention; it already marks all existing pr-debug callsites, only the new drm.debug callsites are initialized to other (DRM_UT_*) values.
_DPRINTK_SITE_UNCLASSED is used in param_set_dyndbg_classbits() to limit the range of bits that are processed to what fits in uint:4. It also terminates the class-id list passed into the macro, so dont use it halfway through your list of classes-to-control.
param_set_dyndbg_classbits() compares new vs old bits, and only updates each class on changes. This maximally preserves the underlying state, which may have been customized at some point via `echo $cmd >control`. So if users really want to know that all prdbgs are set precisely, they must pre-clear then set.
Identity mapping in (A) is encouraged. Your vector should exclude 15, if used, it terminates the list prematurely; any following bit mappings will be ignored (it is the default/non category).
The whole (A) vector/list passed to the macro is:
- not strictly needed: 0-N bits are scanned, only N is needed in the macro interface to do this, not the whole list.
- 0-N list allows juggling the bit->class map Identity map is preferred. 15 terminates list if used. (macro impl does this)
That said, (A) is self-documenting; the explicit list is greppable, 'DRM_UT_*' provides lots of clues. Further, it could be upgraded, something like:
_pick_sym_(DRM_UT_CORE, "mumble something useful about CORE debug")
_pick_sym_(a,b) a // gives us what we need here _pick_help_(a,b) #a " : " b // mod-info fodder
Signed-off-by: Jim Cromie jim.cromie@gmail.com --- include/linux/dynamic_debug.h | 50 +++++++++++++++++++++++ lib/dynamic_debug.c | 77 +++++++++++++++++++++++++++++++++++ 2 files changed, 127 insertions(+)
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h index d4b48f3cc6e8..e83c4e36ad29 100644 --- a/include/linux/dynamic_debug.h +++ b/include/linux/dynamic_debug.h @@ -209,6 +209,10 @@ 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_classbits(const char *instr, const struct kernel_param *kp); +int param_get_dyndbg_classbits(char *buffer, const struct kernel_param *kp); + #else /* !CONFIG_DYNAMIC_DEBUG_CORE */
#include <linux/string.h> @@ -255,6 +259,52 @@ static inline int dynamic_debug_exec_queries(const char *query, const char *modn return 0; }
+struct kernel_param; +static inline int param_set_dyndbg_classbits(const char *instr, const struct kernel_param *kp) +{ return 0; } +static inline int param_get_dyndbg_classbits(char *buffer, const struct kernel_param *kp) +{ return 0; } + #endif /* !CONFIG_DYNAMIC_DEBUG_CORE */
+#define FLAGS_LEN 8 +struct dyndbg_classbits_param { + unsigned long *bits; /* ref to shared state */ + const char flags[FLAGS_LEN]; /* toggle these flags on bit-changes */ + const int classes[]; /* indexed by bitpos */ +}; + +#if defined(CONFIG_DYNAMIC_DEBUG) || defined(CONFIG_DYNAMIC_DEBUG_CORE) +/** + * DEFINE_DYNAMIC_DEBUG_CLASSBITS() - bitmap control of classed pr_debugs + * @sysname: sysfs-node name + * @_var: C-identifier holding bit-vector (Bits 0-14 are usable) + * @_flgs: string with dyndbg flags: 'p' and/or 'T', and maybe "fmlt" also. + * @desc: string summarizing the controls provided + * @classes: vector of callsite.class_id's (uint:4, 15 is reserved) + * + * This macro implements a DRM.debug API style bitmap, mapping bits + * 0-14 to classes of prdbg's, as initialized in their .class_id fields. + * @_flgs chooses the debug recipient; p - syslog, T - tracefs, and + * can include log decorations; m - module, f - function, l - line_num + */ +#define DEFINE_DYNAMIC_DEBUG_CLASSBITS(fsname, _var, _flgs, desc, ...) \ + MODULE_PARM_DESC(fsname, desc); \ + static struct dyndbg_classbits_param ddcats_##_var = { \ + .bits = &(_var), \ + .flags = _flgs, \ + .classes = { __VA_ARGS__, _DPRINTK_SITE_UNCLASSED } \ + }; \ + module_param_cb(fsname, ¶m_ops_dyndbg_classbits, \ + &ddcats_##_var, 0644) + +extern const struct kernel_param_ops param_ops_dyndbg_classbits; + +#else /* no dyndbg configured, throw error on macro use */ + +#define DEFINE_DYNAMIC_DEBUG_CLASSBITS(fsname, var, bitmap_desc, ...) \ + BUILD_BUG_ON_MSG(1, "CONFIG_DYNAMIC_DEBUG* needed to use this macro: " #fsname) + +#endif + #endif diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index ee2129becacc..704361af5b23 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -611,6 +611,83 @@ 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_classbits - bits => categories >control setter + * @instr: string echo>d to sysfs + * @kp: kp->arg has state: bits, map + * + * Enable/disable prdbgs by their "category", as specified in the + * DEFINE_DYNAMIC_DEBUG_BITGRPS.classbits argument. + * + * Returns: 0 or <0 if error. + */ +int param_set_dyndbg_classbits(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_classbits_param *dcp = kp->arg; + + if (!dcp) { + pr_err("set_dyndbg_classbits: no bits=>queries map\n"); + return -EINVAL; + } + rc = kstrtoul(instr, 0, &inbits); + if (rc) { + pr_err("set_dyndbg_classbits: expecting unsigned int\n"); + return rc; + } + vpr_info("set_dyndbg_classbits: new 0x%lx old 0x%lx\n", inbits, *dcp->bits); + + for (i = 0; (i < _DPRINTK_SITE_UNCLASSED && + dcp->classes[i] < _DPRINTK_SITE_UNCLASSED); i++) { + + if (test_bit(i, &inbits) == test_bit(i, dcp->bits)) + continue; + snprintf(query, FMT_QUERY_SIZE, "class %d %cT", + dcp->classes[i], test_bit(i, &inbits) ? '+' : '-'); + + matches = ddebug_exec_queries(query, KP_MOD_NAME); + + v2pr_info("bit-%d: %d matches on class:%u\n", i, + matches, dcp->classes[i]); + totct += matches; + } + *dcp->bits = inbits; + vpr_info("total matches: %d\n", totct); + return 0; +} +EXPORT_SYMBOL(param_set_dyndbg_classbits); + +/** + * param_get_dyndbg_classbits - classbits reader + * @buffer: string description of controlled bits -> classes + * @kp: kp->arg has state: bits, map + * + * Reads last written bits, underlying prdbg state may have changed since. + * Returns: #chars written or <0 on error + */ +int param_get_dyndbg_classbits(char *buffer, const struct kernel_param *kp) +{ + const struct dyndbg_classbits_param *p = kp->arg; + unsigned long val = *p->bits; + + return scnprintf(buffer, PAGE_SIZE, "0x%lx\n", val); +} +EXPORT_SYMBOL(param_get_dyndbg_classbits); + +const struct kernel_param_ops param_ops_dyndbg_classbits = { + .set = param_set_dyndbg_classbits, + .get = param_get_dyndbg_classbits, +}; +EXPORT_SYMBOL(param_ops_dyndbg_classbits); + #define PREFIX_SIZE 64
static int remaining(int wrote)