[RFC PATCH v6 32/34] dyndbg: pack module pr_debug sites

Jim Cromie
2021-05-29T20:03:52Z

In ddebug_add_module, repack the module's sites[] sub-vector.

The previous commit detected 1st site for each function, and ._map'd
2nd-Nth repeats to the 1st. Instead, we now pack the sites[]
sub-vector, by treating it as a stack, and pushing each distinct
site-rec on top, then ._map's 2nd-Nth sites to that top-of-stack.

For loadable modules, this is enough to repack the __dyndbg_sites
elf section. If that section is separately kalloc'd, we could
probably just krealloc it to free the chunk past stack-top.

booting with dynamic_debug.verbose=3 will show:
- cols 3,4 row 1 - skip header
- cols 3,4 - full pack in module's slice of array
- fn count off by 1

rcu: Hierarchical SRCU implementation.
dyndbg: add-module: head64.1 sites
dyndbg: skip header head64
dyndbg: add-module: main.6 sites
Callback from call_rcu_tasks_trace() invoked.
dyndbg: 0 0 1 1 main.run_init_process.1358
dyndbg: 1 0 2 1 main.run_init_process.1356
dyndbg: 2 0 3 1 main.run_init_process.1355
dyndbg: 3 0 4 1 main.run_init_process.1353
dyndbg: 4 1 5 2 main.initcall_blacklisted.1142
dyndbg: 5 2 6 3 main.initcall_blacklist.1103
dyndbg: 6 debug prints in module main (in 2 functions)
dyndbg: add-module: initramfs.1 sites
dyndbg: 0 0 7 7 initramfs.unpack_to_rootfs.496
dyndbg: 1 debug prints in module initramfs (in 0 functions)
dyndbg: add-module: ibs.3 sites
dyndbg: 0 0 8 8 ibs.force_ibs_eilvt_setup.926
dyndbg: 1 1 9 9 ibs.setup_ibs_ctl.897
dyndbg: 2 1 10 9 ibs.setup_ibs_ctl.890
dyndbg: 3 debug prints in module ibs (in 1 functions)

for a loadable module:
- fn-ct looks good
- 1st-fn, packing looks good

dyndbg: add-module: intel_rapl_common.13 sites
dyndbg: 1 1 1 1 intel_rapl_common.rapl_remove_package.1279
dyndbg: 2 2 2 2 intel_rapl_common.rapl_detect_domains.1245
dyndbg: 3 2 3 2 intel_rapl_common.rapl_detect_domains.1242
dyndbg: 4 3 4 3 intel_rapl_common.rapl_package_register_powercap.1159
dyndbg: 5 3 5 3 intel_rapl_common.rapl_package_register_powercap.1145
dyndbg: 6 3 6 3 intel_rapl_common.rapl_package_register_powercap.1114
dyndbg: 7 3 7 3 intel_rapl_common.rapl_package_register_powercap.1108
dyndbg: 8 4 8 4 intel_rapl_common.rapl_update_domain_data.1083
dyndbg: 9 5 9 5 intel_rapl_common.rapl_check_unit_atom.824
dyndbg: 10 6 10 6 intel_rapl_common.rapl_check_unit_core.796
dyndbg: 11 7 11 7 intel_rapl_common.rapl_read_data_raw.722
dyndbg: 12 8 12 8 intel_rapl_common.contraint_to_pl.303
dyndbg: 13 debug prints in module intel_rapl_common (in 8 functions)
dyndbg: add-module: intel_rapl_msr.3 sites
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
lib/dynamic_debug.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index e12538640b51..43f4c82d24c3 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -1073,7 +1073,7 @@ static int __ddebug_add_module(struct _ddebug *tab, struct _ddebug_site *sites,
{
struct ddebug_table *dt;
union _ddebug_header *dh = (union _ddebug_header *) &tab[0];
- int i, j, ct;
+ int i, j;

v3pr_info("add-module: %s.%d sites\n", modname, numdbgs);

@@ -1113,13 +1113,14 @@ static int __ddebug_add_module(struct _ddebug *tab, struct _ddebug_site *sites,
* we watch for repeats on site.function, and reuse the index
* of the 1st site record in a repeating block.
*/
- for (ct = i = j = 0; i < numdbgs; i++) {
+ for (i = j = 0; i < numdbgs; i++) {
tab[i]._back = base + i; /* index back to header */

- if (sites[i].function != sites[j].function) {
- j = i; /* remember 1st row with new fn */
- ct++;
- }
+ /* find 1st row with new fn, copy it to stack on j */
+ if (sites[i].function != sites[j].function)
+ memcpy((void *) &sites[++j], (void *) &sites[i],
+ sizeof(struct _ddebug_site));
+
tab[i]._map = base + j;

v3pr_info(" %d %d %d %d %s.%s.%d\n", i, j, tab[i]._back, tab[i]._map,
@@ -1131,7 +1132,7 @@ static int __ddebug_add_module(struct _ddebug *tab, struct _ddebug_site *sites,
mutex_unlock(&ddebug_lock);

v2pr_info("%3u debug prints in module %s (in %d functions)\n",
- numdbgs, modname, ++ct);
+ numdbgs, modname, j);

return 0;
}
--
2.31.1