2019-10-29 20:11:08

by Jim Cromie

[permalink] [raw]
Subject: [PATCH 04/16] dyndbg: rename __verbose section to __dyndbg

dyndbg populates its callsite info into __verbose section, change that
to a more specific and descriptive name, __dyndbg.

Also, per checkpatch:
move extern struct _ddebug __(start|stop)__dyndbg[] to header file
simplify __attribute(..) to __section(__dyndbg) declaration.

Signed-off-by: Jim Cromie <[email protected]>
---
include/asm-generic/vmlinux.lds.h | 6 +++---
include/linux/dynamic_debug.h | 4 +++-
kernel/module.c | 2 +-
lib/dynamic_debug.c | 10 ++++------
4 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index dae64600ccbf..82694efe3a83 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -285,9 +285,9 @@
*(__tracepoints) \
/* implement dynamic printk debug */ \
. = ALIGN(8); \
- __start___verbose = .; \
- KEEP(*(__verbose)) \
- __stop___verbose = .; \
+ __start___dyndbg = .; \
+ KEEP(*(__dyndbg)) \
+ __stop___dyndbg = .; \
LIKELY_PROFILE() \
BRANCH_PROFILE() \
TRACE_PRINTKS() \
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index 6c809440f319..a829c86364d4 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -46,6 +46,8 @@ struct _ddebug {
#endif
} __attribute__((aligned(8)));

+extern struct _ddebug __start___dyndbg[];
+extern struct _ddebug __stop___dyndbg[];


#if defined(CONFIG_DYNAMIC_DEBUG)
@@ -80,7 +82,7 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,

#define DEFINE_DYNAMIC_DEBUG_METADATA(name, fmt) \
static struct _ddebug __aligned(8) \
- __attribute__((section("__verbose"))) name = { \
+ __section(__dyndbg) name = { \
.modname = KBUILD_MODNAME, \
.function = __func__, \
.filename = __FILE__, \
diff --git a/kernel/module.c b/kernel/module.c
index ff2d7359a418..a9c052cc30c5 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3237,7 +3237,7 @@ static int find_module_sections(struct module *mod, struct load_info *info)
if (section_addr(info, "__obsparm"))
pr_warn("%s: Ignoring obsolete parameters\n", mod->name);

- info->debug = section_objs(info, "__verbose",
+ info->debug = section_objs(info, "__dyndbg",
sizeof(*info->debug), &info->num_debug);

return 0;
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index f82ec49e5916..6eec5bd559fe 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -39,8 +39,6 @@

#include <rdma/ib_verbs.h>

-extern struct _ddebug __start___verbose[];
-extern struct _ddebug __stop___verbose[];

struct ddebug_table {
struct list_head link;
@@ -997,14 +995,14 @@ static int __init dynamic_debug_init(void)
int n = 0, entries = 0, modct = 0;
int verbose_bytes = 0;

- if (__start___verbose == __stop___verbose) {
+ if (__start___dyndbg == __stop___dyndbg) {
pr_warn("_ddebug table is empty in a CONFIG_DYNAMIC_DEBUG build\n");
return 1;
}
- iter = __start___verbose;
+ iter = __start___dyndbg;
modname = iter->modname;
iter_start = iter;
- for (; iter < __stop___verbose; iter++) {
+ for (; iter < __stop___dyndbg; iter++) {
entries++;
verbose_bytes += strlen(iter->modname) + strlen(iter->function)
+ strlen(iter->filename) + strlen(iter->format);
@@ -1027,7 +1025,7 @@ static int __init dynamic_debug_init(void)
ddebug_init_success = 1;
vpr_info("%d modules, %d entries and %d bytes in ddebug tables, %d bytes in (readonly) verbose section\n",
modct, entries, (int)(modct * sizeof(struct ddebug_table)),
- verbose_bytes + (int)(__stop___verbose - __start___verbose));
+ verbose_bytes + (int)(__stop___dyndbg - __start___dyndbg));

/* apply ddebug_query boot param, dont unload tables on err */
if (ddebug_setup_string[0] != '\0') {
--
2.21.0


2019-10-29 21:28:25

by Jim Cromie

[permalink] [raw]
Subject: Re: [PATCH 04/16] dyndbg: rename __verbose section to __dyndbg

On Tue, Oct 29, 2019 at 2:37 PM Rasmus Villemoes
<[email protected]> wrote:
>
> On 29/10/2019 21.00, Jim Cromie wrote:
> > dyndbg populates its callsite info into __verbose section, change that
> > to a more specific and descriptive name, __dyndbg.
>
> Yeah, that has always bugged me. Ack to that part.
>
> > Also, per checkpatch:
> > move extern struct _ddebug __(start|stop)__dyndbg[] to header file
>
> Hm, why? checkpatch should often be ignored. Since we only refer to
> those symbols in the .c file, there's no reason to pollute every other
> translation unit with those declarations. Having declarations in a
> header makes sense when the actual entity gets defined in some .c file
> (which hopefully also includes the header). But these are defined by the
> linker, so there's no type safety to be had.
>

checkpatch wasnt in a mood to explain itself,
but the other simplification seemed good, credit by association

I guess the action-at-a-distance feel to the linker magic
and the extern qualifier, swung me toward heeding the advice.
OTOH, as you note, only dyndbg should be mucking with the symbols.



> > simplify __attribute(..) to __section(__dyndbg) declaration.
>
> Makes sense, since you're munching the thing anyway.
>
> Rasmus

2019-10-29 22:09:38

by Rasmus Villemoes

[permalink] [raw]
Subject: Re: [PATCH 04/16] dyndbg: rename __verbose section to __dyndbg

On 29/10/2019 21.00, Jim Cromie wrote:
> dyndbg populates its callsite info into __verbose section, change that
> to a more specific and descriptive name, __dyndbg.

Yeah, that has always bugged me. Ack to that part.

> Also, per checkpatch:
> move extern struct _ddebug __(start|stop)__dyndbg[] to header file

Hm, why? checkpatch should often be ignored. Since we only refer to
those symbols in the .c file, there's no reason to pollute every other
translation unit with those declarations. Having declarations in a
header makes sense when the actual entity gets defined in some .c file
(which hopefully also includes the header). But these are defined by the
linker, so there's no type safety to be had.

> simplify __attribute(..) to __section(__dyndbg) declaration.

Makes sense, since you're munching the thing anyway.

Rasmus