Demonstrate dyndbg's "class FOO" and bitmap-to-classes support. This support is meant to plug into drm.debug system, and largely replace the use of drm_debug_enabled(category) with JUMP_LABELs.
Recap: #> echo class DRM_UT_CORE +p > /proc/dynamic_debug/control
This is made "safe" because dyndbg skips it for any modules which don't know that class (havent called dynamic_debug_register_classes).
Other modules may use the same .class_id for a separate classified debug scheme.
Use the API:
- DYNAMIC_DEBUG_CLASSES(_var, classes), to declare static _var by name - dynamic_debug_register_classes(_var) - dynamic_debug_unregister_classes(_var)
Use these 3 times; with base = 0,8,16 respectively, to demonstrate the segmenting of the module's .class_id range [0..30]
For each of those 3 class-name-sets, add 2 sysfs-node-bitmaps, one each for p-syslog, and T-tracefs, the latter will work once dyndbg gets that patchset.
#> modprobe test_dynamic_debug dyndbg=+pfm #> cat /sys/module/test_dynamic_debug/parameters/do_prints #> echo class FOO +pf > /proc/dynamic_debug/control #> echo class Foo +pfm > /proc/dynamic_debug/control #> cat /sys/module/test_dynamic_debug/parameters/do_prints
RFC:
This use case exposes a weak point in the api; the 2nd query command given in the dyndbg option will not work like the 1st:
#> modprobe test_dynamic_debug dyndbg='+pfm; class FOO +pfm'
This is because the option is processed early in module-load, well before the registration can attach the class-map to the module's ddebug_table entry.
Signed-off-by: Jim Cromie jim.cromie@gmail.com --- MAINTAINERS | 1 + lib/Kconfig.debug | 11 +++ lib/Makefile | 1 + lib/test_dynamic_debug.c | 172 +++++++++++++++++++++++++++++++++++++++ 4 files changed, 185 insertions(+) create mode 100644 lib/test_dynamic_debug.c
diff --git a/MAINTAINERS b/MAINTAINERS index e8c52d0192a6..bf615853be47 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -6918,6 +6918,7 @@ M: Jason Baron jbaron@akamai.com S: Maintained F: include/linux/dynamic_debug.h F: lib/dynamic_debug.c +F: lib/test_dynamic_debug.c
DYNAMIC INTERRUPT MODERATION M: Tal Gilboa talgi@nvidia.com diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 075cd25363ac..c88d691d3df1 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -2601,6 +2601,17 @@ config TEST_STATIC_KEYS
If unsure, say N.
+config TEST_DYNAMIC_DEBUG + tristate "Test DYNAMIC_DEBUG" + depends on m + depends on DYNAMIC_DEBUG + help + This module registers a tracer callback to count enabled + pr_debugs in a 'do_debugging' function, then alters their + enablements, calls the function, and compares counts. + + If unsure, say N. + config TEST_KMOD tristate "kmod stress tester" depends on m diff --git a/lib/Makefile b/lib/Makefile index 6b9ffc1bd1ee..e5727fbbfc7d 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -82,6 +82,7 @@ obj-$(CONFIG_TEST_SORT) += test_sort.o obj-$(CONFIG_TEST_USER_COPY) += test_user_copy.o obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_keys.o obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_key_base.o +obj-$(CONFIG_TEST_DYNAMIC_DEBUG) += test_dynamic_debug.o obj-$(CONFIG_TEST_PRINTF) += test_printf.o obj-$(CONFIG_TEST_SCANF) += test_scanf.o obj-$(CONFIG_TEST_BITMAP) += test_bitmap.o diff --git a/lib/test_dynamic_debug.c b/lib/test_dynamic_debug.c new file mode 100644 index 000000000000..65c37ba6c0da --- /dev/null +++ b/lib/test_dynamic_debug.c @@ -0,0 +1,172 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Kernel module for testing dynamic_debug + * + * Authors: + * Jim Cromie jim.cromie@gmail.com + */ + +#define pr_fmt(fmt) "test_dd: " fmt + +#include <linux/module.h> + +static void do_prints(void); /* device under test */ + +/* run tests by reading or writing sysfs node */ + +int param_set_do_prints(const char *instr, const struct kernel_param *kp) +{ + do_prints(); + return 0; +} +EXPORT_SYMBOL(param_set_do_prints); + +int param_get_do_prints(char *buffer, const struct kernel_param *kp) +{ + do_prints(); + return scnprintf(buffer, PAGE_SIZE, "did do_prints\n"); +} +EXPORT_SYMBOL(param_get_do_prints); + +const struct kernel_param_ops param_ops_do_prints = { + .set = param_set_do_prints, + .get = param_get_do_prints, +}; +EXPORT_SYMBOL(param_ops_do_prints); + +module_param_cb(do_prints, ¶m_ops_do_prints, NULL, 0600); + +/* + * Declare 3 groups of classes, with different .class_id[] ranges, + * each with 2 sysfs-node bitmaps controlling p,T flags respectively + * for those named classes. This example is rather more involved than + * anyone will likely use. + + * The T-bitmap sysfs-node functionality will need a few patches which + * add trace-events to dyndbg. + + * Rules: + * - enum symbols must match/correlate with class-name strings + * - base must equal enum's 1st value + */ + +enum cat1 { FOO, BAR, BUZZ }; +DYNAMIC_DEBUG_CLASSES(ddt_classes1, 0, + "FOO", "BAR", "BUZZ"); + +unsigned long bits_1p, bits_1t; +EXPORT_SYMBOL(bits_1p); +EXPORT_SYMBOL(bits_1t); + +static struct ddebug_classes_bitmap_param p1_bitmap = { + .bits = &bits_1p, + .flags = "p", + .map = &ddt_classes1 +}; +module_param_cb(c1_syslog_bits, ¶m_ops_dyndbg_classes, &p1_bitmap, 0600); + +static struct ddebug_classes_bitmap_param t1_bitmap = { + .bits = &bits_1t, + .flags = "T", + .map = &ddt_classes1 +}; +module_param_cb(c1_trace_bits, ¶m_ops_dyndbg_classes, &t1_bitmap, 0600); + + +enum cat2 { Foo = 8, Bar, Buzz }; +DYNAMIC_DEBUG_CLASSES(ddt_classes2, 8, + "Foo", "Bar", "Buzz"); + +unsigned long bits_2p, bits_2t; +EXPORT_SYMBOL(bits_2p); +EXPORT_SYMBOL(bits_2t); + +static struct ddebug_classes_bitmap_param p2_bitmap = { + .bits = &bits_2p, + .flags = "p", + .map = &ddt_classes2 +}; +module_param_cb(c2_syslog_bits, ¶m_ops_dyndbg_classes, &p2_bitmap, 0600); + +static struct ddebug_classes_bitmap_param t2_bitmap = { + .bits = &bits_2t, + .flags = "T", + .map = &ddt_classes2 +}; +module_param_cb(c2_trace_bits, ¶m_ops_dyndbg_classes, &t2_bitmap, 0600); + + +enum cat3 { bing = 16, bong, boom }; +DYNAMIC_DEBUG_CLASSES(ddt_classes3, 16, + "bing", "bong", "boom"); + +unsigned long bits_3p, bits_3t; +EXPORT_SYMBOL(bits_3p); +EXPORT_SYMBOL(bits_3t); + +static struct ddebug_classes_bitmap_param p3_bitmap = { + .bits = &bits_3p, + .flags = "p", + .map = &ddt_classes3 +}; +module_param_cb(c3_syslog_bits, ¶m_ops_dyndbg_classes, &p3_bitmap, 0600); + +static struct ddebug_classes_bitmap_param t3_bitmap = { + .bits = &bits_3t, + .flags = "T", + .map = &ddt_classes3 +}; +module_param_cb(c3_trace_bits, ¶m_ops_dyndbg_classes, &t3_bitmap, 0600); + +static void do_prints(void) +{ + /* raw integer classes */ + __pr_debug_cls(0, "class 0"); + __pr_debug_cls(1, "class 1"); + __pr_debug_cls(2, "class 2"); + + /* enum ints */ + __pr_debug_cls(FOO, "class FOO"); + __pr_debug_cls(BAR, "class BAR"); + __pr_debug_cls(BUZZ, "class BUZZ"); + + __pr_debug_cls(Foo, "class Foo"); + __pr_debug_cls(Bar, "class Bar"); + __pr_debug_cls(Buzz, "class Buzz"); + + __pr_debug_cls(bing, "class bing"); + __pr_debug_cls(bong, "class bong"); + __pr_debug_cls(boom, "class boom"); +} + +static int __init test_dynamic_debug_init(void) +{ + pr_debug("module-init\n"); + /* + * these are too late to enable class FOO at module load time: + * #> modprobe test_dynamic_debug dyndbg='class FOO +p' + */ + dynamic_debug_register_classes(&ddt_classes1); + dynamic_debug_register_classes(&ddt_classes2); + dynamic_debug_register_classes(&ddt_classes3); + + do_prints(); + + pr_debug("module-init done\n"); + return 0; +} + +static void __exit test_dynamic_debug_exit(void) +{ + dynamic_debug_unregister_classes(&ddt_classes1); + dynamic_debug_unregister_classes(&ddt_classes2); + dynamic_debug_unregister_classes(&ddt_classes3); + + pr_debug("module-exit\n"); +} + +module_init(test_dynamic_debug_init); +module_exit(test_dynamic_debug_exit); + +MODULE_AUTHOR("Jim Cromie jim.cromie@gmail.com"); +MODULE_LICENSE("GPL");