Split the struct into 2 linked parts (head & body) so that next, struct _ddebug_callsite can be off-lined to zram, and only mapped in as needed. The split increases overall memory use by 1 pointer per callsite, but 4 pointers and a short are now 99% likely to be off-line (once implemented). dyndbg: 264 modules, 2541 entries and 10560 bytes in ddebug tables,\ 81312 bytes in __dyndbg section, 101640 bytes in __dyndbg_callsites section zram should give us some compression on the _ddebug_callsite data, and if it doesn't, a simple run-length-encoder would be effective enough, given the repetition on (modname,filename,function) of (90%,84%,45%) and the highly ordered contents of the __ddebug_callsites section. I wanted to also put the key field into _ddebug_callsite, since its use is super rare; it is only used when enabling/disabling a callsite, ie only when >control is being actively exersized. But that blew up with asm goto errors, so I punted. So struct _ddebug_callsite is all const, RO data. Maybe thats advantageous later, but with key there too, we can shrink the online struct _ddebug further. details of how: dynamic_debug.h: I literally cut struct _ddebug in half, renamed top-half, kept __align(8) on both, added forward decl for unified comment (not needed by compiler), and a site pointer from _ddebug to _ddebug_callsite, and a few "->site" additions. DECLARE_DYNAMIC_DEBUG_METADATA does the rest; it declares and initializes both static struct vars together, and refs one to the other. Note: this may conflict with new guards against cross-linked sections, but __init work on __initdata seems a fair loophole. dynamic_debug.c: dynamic_debug_init() gets "->site" added everywhere needed. Other 3 runtime users get a new _ddebug_callsite *dc pointer, initialized with a single dp->site deref, and s/dp/dc/ as needed. These one per func dp->site derefs are a setup for the next commit. vmlinux.lds.h: add __ddebug_callsites section, with the same align(8) and KEEP as used in the __ddebug section. I suspect keep may go as a part of causing the section reclaim. Signed-off-by: Jim Cromie <jim.cromie@gmail.com> --- include/asm-generic/vmlinux.lds.h | 4 +++ include/linux/dynamic_debug.h | 38 ++++++++++++++++------ lib/dynamic_debug.c | 52 +++++++++++++++++-------------- 3 files changed, 60 insertions(+), 34 deletions(-) diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index c78629ec79b6..c874216c01f5 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -320,6 +320,10 @@ *(__tracepoints) \ /* implement dynamic printk debug */ \ . = ALIGN(8); \ + __start___dyndbg_callsites = .; \ + KEEP(*(__dyndbg_callsites)) \ + __stop___dyndbg_callsites = .; \ + . = ALIGN(8); \ __start___dyndbg = .; \ KEEP(*(__dyndbg)) \ __stop___dyndbg = .; \ diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h index aa9ff9e1c0b3..1bf52952df69 100644 --- a/include/linux/dynamic_debug.h +++ b/include/linux/dynamic_debug.h @@ -7,11 +7,15 @@ #endif /* - * An instance of this structure is created in a special - * ELF section at every dynamic debug callsite. At runtime, - * the special section is treated as an array of these. + * a pair of these structs are created in 2 special ELF sections + * (__dyndbg, __dyndbg_callsites) for every dynamic debug callsite. + * During init, __dyndbg_callsites is copied to zram, and links to + * them in _ddebug are updated. At runtime, the __dyndbg section is + * treated as an array of struct _ddebugs. */ -struct _ddebug { +struct _ddebug; +struct _ddebug_callsite { + /* * These fields are used to drive the user interface * for selecting and displaying debug callsites. @@ -20,7 +24,12 @@ struct _ddebug { const char *function; const char *filename; const char *format; - unsigned int lineno:18; + const unsigned int lineno:16; +} __aligned(8); + +struct _ddebug { + struct _ddebug_callsite *site; + /* * The flags field controls the behaviour at the callsite. * The bits here are changed dynamically when the user @@ -32,21 +41,26 @@ struct _ddebug { #define _DPRINTK_FLAGS_INCL_FUNCNAME (1<<2) #define _DPRINTK_FLAGS_INCL_LINENO (1<<3) #define _DPRINTK_FLAGS_INCL_TID (1<<4) +#define _DPRINTK_FLAGS_MAPPED (1<<7) /* reserved */ #if defined DEBUG #define _DPRINTK_FLAGS_DEFAULT _DPRINTK_FLAGS_PRINT #else #define _DPRINTK_FLAGS_DEFAULT 0 #endif unsigned int flags:8; + /* + * TODO: key probably should be in _callsite, based upon how + * little it is used (only on callsite enable/disable). But + * that gave weird asm goto errors in jump_label.h and I + * punted. + */ #ifdef CONFIG_JUMP_LABEL union { struct static_key_true dd_key_true; struct static_key_false dd_key_false; } key; #endif -} __attribute__((aligned(8))); - - +} __aligned(8); #if defined(CONFIG_DYNAMIC_DEBUG_CORE) int ddebug_add_module(struct _ddebug *tab, unsigned int n, @@ -79,13 +93,17 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor, const char *fmt, ...); #define DEFINE_DYNAMIC_DEBUG_METADATA(name, fmt) \ - static struct _ddebug __aligned(8) \ - __section(__dyndbg) name = { \ + static struct _ddebug_callsite __aligned(8) \ + __section(__dyndbg_callsites) name##_site = { \ .modname = KBUILD_MODNAME, \ .function = __func__, \ .filename = __FILE__, \ .format = (fmt), \ .lineno = __LINE__, \ + }; \ + static struct _ddebug __aligned(8) \ + __section(__dyndbg) name = { \ + .site = &name##_site, \ .flags = _DPRINTK_FLAGS_DEFAULT, \ _DPRINTK_KEY_INIT \ } diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index 691e79826fc2..9161f345e3c9 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -165,19 +165,20 @@ static int ddebug_change(const struct ddebug_query *query, for (i = 0; i < dt->num_ddebugs; i++) { struct _ddebug *dp = &dt->ddebugs[i]; + struct _ddebug_callsite *dc = dp->site; /* match against the source filename */ if (query->filename && - !match_wildcard(query->filename, dp->filename) && + !match_wildcard(query->filename, dc->filename) && !match_wildcard(query->filename, - kbasename(dp->filename)) && + kbasename(dc->filename)) && !match_wildcard(query->filename, - trim_prefix(dp->filename))) + trim_prefix(dc->filename))) continue; /* match against the function */ if (query->function && - !match_wildcard(query->function, dp->function)) + !match_wildcard(query->function, dc->function)) continue; /* match against the format */ @@ -185,19 +186,19 @@ static int ddebug_change(const struct ddebug_query *query, if (*query->format == '^') { char *p; /* anchored search. match must be at beginning */ - p = strstr(dp->format, query->format+1); - if (p != dp->format) + p = strstr(dc->format, query->format+1); + if (p != dc->format) continue; - } else if (!strstr(dp->format, query->format)) + } else if (!strstr(dc->format, query->format)) continue; } /* match against the line number range */ if (query->first_lineno && - dp->lineno < query->first_lineno) + dc->lineno < query->first_lineno) continue; if (query->last_lineno && - dp->lineno > query->last_lineno) + dc->lineno > query->last_lineno) continue; nfound++; @@ -214,8 +215,8 @@ static int ddebug_change(const struct ddebug_query *query, #endif dp->flags = newflags; v2pr_info("changed %s:%d [%s]%s =%s\n", - trim_prefix(dp->filename), dp->lineno, - dt->mod_name, dp->function, + trim_prefix(dc->filename), dc->lineno, + dt->mod_name, dc->function, ddebug_describe_flags(dp->flags, &fbuf)); } } @@ -568,14 +569,15 @@ static int remaining(int wrote) return 0; } -static char *dynamic_emit_prefix(const struct _ddebug *desc, char *buf) +static char *dynamic_emit_prefix(const struct _ddebug *dp, char *buf) { int pos_after_tid; int pos = 0; + const struct _ddebug_callsite *desc = dp->site; *buf = '\0'; - if (desc->flags & _DPRINTK_FLAGS_INCL_TID) { + if (dp->flags & _DPRINTK_FLAGS_INCL_TID) { if (in_interrupt()) pos += snprintf(buf + pos, remaining(pos), "<intr> "); else @@ -583,13 +585,13 @@ static char *dynamic_emit_prefix(const struct _ddebug *desc, char *buf) task_pid_vnr(current)); } pos_after_tid = pos; - if (desc->flags & _DPRINTK_FLAGS_INCL_MODNAME) + if (dp->flags & _DPRINTK_FLAGS_INCL_MODNAME) pos += snprintf(buf + pos, remaining(pos), "%s:", desc->modname); - if (desc->flags & _DPRINTK_FLAGS_INCL_FUNCNAME) + if (dp->flags & _DPRINTK_FLAGS_INCL_FUNCNAME) pos += snprintf(buf + pos, remaining(pos), "%s:", desc->function); - if (desc->flags & _DPRINTK_FLAGS_INCL_LINENO) + if (dp->flags & _DPRINTK_FLAGS_INCL_LINENO) pos += snprintf(buf + pos, remaining(pos), "%d:", desc->lineno); if (pos - pos_after_tid) @@ -861,6 +863,7 @@ static int ddebug_proc_show(struct seq_file *m, void *p) { struct ddebug_iter *iter = m->private; struct _ddebug *dp = p; + struct _ddebug_callsite *dc = dp->site; struct flagsbuf flags; if (p == SEQ_START_TOKEN) { @@ -870,10 +873,10 @@ static int ddebug_proc_show(struct seq_file *m, void *p) } seq_printf(m, "%s:%u [%s]%s =%s \"", - trim_prefix(dp->filename), dp->lineno, - iter->table->mod_name, dp->function, + trim_prefix(dc->filename), dc->lineno, + iter->table->mod_name, dc->function, ddebug_describe_flags(dp->flags, &flags)); - seq_escape(m, dp->format, "\t\r\n\""); + seq_escape(m, dc->format, "\t\r\n\""); seq_puts(m, "\"\n"); return 0; @@ -1076,7 +1079,7 @@ static int __init dynamic_debug_init(void) return 0; } iter = __start___dyndbg; - modname = iter->modname; + modname = iter->site->modname; iter_start = iter; for (prev = iter; iter < __stop___dyndbg; iter++) { if (entries) { @@ -1089,13 +1092,13 @@ static int __init dynamic_debug_init(void) prev++; /* one behind iter */ } entries++; - if (strcmp(modname, iter->modname)) { + if (strcmp(modname, iter->site->modname)) { modct++; ret = ddebug_add_module(iter_start, n, modname); if (ret) goto out_err; n = 0; - modname = iter->modname; + modname = iter->site->modname; iter_start = iter; } n++; @@ -1105,9 +1108,10 @@ static int __init dynamic_debug_init(void) goto out_err; ddebug_init_success = 1; - vpr_info("%d modules, %d entries and %d bytes in ddebug tables, %d bytes in __dyndbg section\n", + vpr_info("%d modules, %d entries and %d bytes in ddebug tables, %d bytes in __dyndbg section, %d bytes in __dyndbg_callsites section\n", modct, entries, (int)(modct * sizeof(struct ddebug_table)), - (int)(entries * sizeof(struct _ddebug))); + (int)(entries * sizeof(struct _ddebug)), + (int)(entries * sizeof(struct _ddebug_callsite))); vpr_info("%d entries. repeated entries: %d module %d file %d func\n", entries, modreps, filereps, funcreps); -- 2.26.2