The patch titled
Subject: dynamic_debug: add jump label support
has been added to the -mm tree. Its filename is
dynamic_debug-add-jump-label-support.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/dynamic_debug-add-jump-label-support.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/dynamic_debug-add-jump-label-support.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Jason Baron <jbaron@xxxxxxxxxx>
Subject: dynamic_debug: add jump label support
Although dynamic debug is often only used for debug builds, sometimes its
enabled for production builds as well. Minimize its impact by using jump
labels. This reduces the text section by 6000+ bytes in the kernel image
below. It does increae data, but this should only be referenced when
changing the direction of the branches, and hence usually not in cache.
text data bss dec hex filename
10369421 2033336 917504 13320261 cb4045 vmlinux.pre
10363054 2103736 917504 13384294 cc3a66 vmlinux.post
Signed-off-by: Jason Baron <jbaron@xxxxxxxxxx>
Cc: Joe Perches <joe@xxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/dynamic_debug.h | 54 ++++++++++++++++++++++++++++----
lib/dynamic_debug.c | 7 ++++
2 files changed, 55 insertions(+), 6 deletions(-)
diff -puN include/linux/dynamic_debug.h~dynamic_debug-add-jump-label-support include/linux/dynamic_debug.h
--- a/include/linux/dynamic_debug.h~dynamic_debug-add-jump-label-support
+++ a/include/linux/dynamic_debug.h
@@ -1,6 +1,8 @@
#ifndef _DYNAMIC_DEBUG_H
#define _DYNAMIC_DEBUG_H
+#include <linux/jump_label_branch.h>
+
/*
* An instance of this structure is created in a special
* ELF section at every dynamic debug callsite. At runtime,
@@ -33,6 +35,12 @@ struct _ddebug {
#define _DPRINTK_FLAGS_DEFAULT 0
#endif
unsigned int flags:8;
+#ifdef HAVE_JUMP_LABEL
+ union {
+ struct static_key_true dd_key_true;
+ struct static_key_false dd_key_false;
+ } key;
+#endif
} __attribute__((aligned(8)));
@@ -60,7 +68,7 @@ void __dynamic_netdev_dbg(struct _ddebug
const struct net_device *dev,
const char *fmt, ...);
-#define DEFINE_DYNAMIC_DEBUG_METADATA(name, fmt) \
+#define DEFINE_DYNAMIC_DEBUG_METADATA_KEY(name, fmt, key, init) \
static struct _ddebug __aligned(8) \
__attribute__((section("__verbose"))) name = { \
.modname = KBUILD_MODNAME, \
@@ -68,13 +76,47 @@ void __dynamic_netdev_dbg(struct _ddebug
.filename = __FILE__, \
.format = (fmt), \
.lineno = __LINE__, \
- .flags = _DPRINTK_FLAGS_DEFAULT, \
+ .flags = _DPRINTK_FLAGS_DEFAULT, \
+ dd_key_init(key, init) \
}
+#ifdef HAVE_JUMP_LABEL
+
+#define dd_key_init(key, init) key = (init)
+
+#ifdef DEBUG
+#define DEFINE_DYNAMIC_DEBUG_METADATA(name, fmt) \
+ DEFINE_DYNAMIC_DEBUG_METADATA_KEY(name, fmt, .key.dd_key_true, \
+ (STATIC_KEY_TRUE_INIT))
+
+#define DDEBUG_BRANCH(descriptor) \
+ static_branch_likely(&descriptor.key.dd_key_true)
+#else
+#define DEFINE_DYNAMIC_DEBUG_METADATA(name, fmt) \
+ DEFINE_DYNAMIC_DEBUG_METADATA_KEY(name, fmt, .key.dd_key_false, \
+ (STATIC_KEY_FALSE_INIT))
+
+#define DDEBUG_BRANCH(descriptor) \
+ static_branch_unlikely(&descriptor.key.dd_key_false)
+#endif
+
+#else
+
+#define dd_key_init(key, init)
+
+#define DEFINE_DYNAMIC_DEBUG_METADATA(name, fmt) \
+ DEFINE_DYNAMIC_DEBUG_METADATA_KEY(name, fmt, .key.dd_key_false, \
+ (STATIC_KEY_FALSE_INIT))
+
+#define DDEBUG_BRANCH(descriptor) \
+ unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT)
+
+#endif
+
#define dynamic_pr_debug(fmt, ...) \
do { \
DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt); \
- if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT)) \
+ if (DDEBUG_BRANCH(descriptor)) \
__dynamic_pr_debug(&descriptor, pr_fmt(fmt), \
##__VA_ARGS__); \
} while (0)
@@ -82,7 +124,7 @@ do { \
#define dynamic_dev_dbg(dev, fmt, ...) \
do { \
DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt); \
- if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT)) \
+ if (DDEBUG_BRANCH(descriptor)) \
__dynamic_dev_dbg(&descriptor, dev, fmt, \
##__VA_ARGS__); \
} while (0)
@@ -90,7 +132,7 @@ do { \
#define dynamic_netdev_dbg(dev, fmt, ...) \
do { \
DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt); \
- if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT)) \
+ if (DDEBUG_BRANCH(descriptor)) \
__dynamic_netdev_dbg(&descriptor, dev, fmt, \
##__VA_ARGS__); \
} while (0)
@@ -100,7 +142,7 @@ do { \
do { \
DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, \
__builtin_constant_p(prefix_str) ? prefix_str : "hexdump");\
- if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT)) \
+ if (DDEBUG_BRANCH(descriptor)) \
print_hex_dump(KERN_DEBUG, prefix_str, \
prefix_type, rowsize, groupsize, \
buf, len, ascii); \
diff -puN lib/dynamic_debug.c~dynamic_debug-add-jump-label-support lib/dynamic_debug.c
--- a/lib/dynamic_debug.c~dynamic_debug-add-jump-label-support
+++ a/lib/dynamic_debug.c
@@ -188,6 +188,13 @@ static int ddebug_change(const struct dd
newflags = (dp->flags & mask) | flags;
if (newflags == dp->flags)
continue;
+#ifdef HAVE_JUMP_LABEL
+ if (dp->flags & _DPRINTK_FLAGS_PRINT) {
+ if (!(flags & _DPRINTK_FLAGS_PRINT))
+ static_branch_disable(&dp->key.dd_key_true);
+ } else if (flags & _DPRINTK_FLAGS_PRINT)
+ static_branch_enable(&dp->key.dd_key_true);
+#endif
dp->flags = newflags;
vpr_info("changed %s:%d [%s]%s =%s\n",
trim_prefix(dp->filename), dp->lineno,
_
Patches currently in -mm which might be from jbaron@xxxxxxxxxx are
jump_label-create-jump_label_branchh.patch
powerpc-add-explicit-include-asm-asm-compath-for-jump-label.patch
dynamic_debug-add-jump-label-support.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
