Re: Re: [PATCH v2 1/4] kprobes: delay blacklist symbol lookup until we actually need it
Thanks for your input guys!
On 04:16 Fri 05 Apr , Masami Hiramatsu wrote:
> (2013/04/05 9:56), Joonsoo Kim wrote:
> > Hello, Oskar.
> >
> > On Thu, Apr 04, 2013 at 02:51:26PM +0200, Oskar Andero wrote:
> >> From: Toby Collett
> >>
> >> The symbol lookup can take a long time and kprobes is
> >> initialised very early in boot, so delay symbol lookup
> >> until the blacklist is first used.
> >>
> >> Cc: Masami Hiramatsu
> >> Cc: David S. Miller
> >> Reviewed-by: Radovan Lekanovic
> >> Signed-off-by: Toby Collett
> >> Signed-off-by: Oskar Andero
> >> ---
> >> kernel/kprobes.c | 98
> >> ++--
> >> 1 file changed, 60 insertions(+), 38 deletions(-)
> >>
> >> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> >> index e35be53..0a270e5 100644
> >> --- a/kernel/kprobes.c
> >> +++ b/kernel/kprobes.c
> >> @@ -68,6 +68,7 @@
> >> #endif
> >>
> >> static int kprobes_initialized;
> >> +static int kprobe_blacklist_initialized;
> >> static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
> >> static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
> >>
> >> @@ -102,6 +103,60 @@ static struct kprobe_blackpoint kprobe_blacklist[] = {
> >>{NULL}/* Terminator */
> >> };
> >>
> >> +/* it can take some time ( > 100ms ) to initialise the
> >> + * blacklist so we delay this until we actually need it
> >> + */
> >> +static void init_kprobe_blacklist(void)
> >> +{
> >> + int i;
> >> + unsigned long offset = 0, size = 0;
> >> + char *modname, namebuf[128];
> >> + const char *symbol_name;
> >> + void *addr;
> >> + struct kprobe_blackpoint *kb;
> >> +
> >> + mutex_lock(_mutex);
> >> + if (kprobe_blacklist_initialized)
> >> + goto out;
> >> +
> >> + /*
> >> + * Lookup and populate the kprobe_blacklist.
> >> + *
> >> + * Unlike the kretprobe blacklist, we'll need to determine
> >> + * the range of addresses that belong to the said functions,
> >> + * since a kprobe need not necessarily be at the beginning
> >> + * of a function.
> >> + */
> >> + for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
> >> + kprobe_lookup_name(kb->name, addr);
> >> + if (!addr)
> >> + continue;
> >> +
> >> + kb->start_addr = (unsigned long)addr;
> >> + symbol_name = kallsyms_lookup(kb->start_addr,
> >> + , , , namebuf);
> >> + if (!symbol_name)
> >> + kb->range = 0;
> >> + else
> >> + kb->range = size;
> >> + }
> >> +
> >> + if (kretprobe_blacklist_size) {
> >> + /* lookup the function address from its name */
> >> + for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
> >> + kprobe_lookup_name(kretprobe_blacklist[i].name,
> >> + kretprobe_blacklist[i].addr);
> >> + if (!kretprobe_blacklist[i].addr)
> >> + printk("kretprobe: lookup failed: %s\n",
> >> + kretprobe_blacklist[i].name);
> >> + }
> >> + }
> >> + kprobe_blacklist_initialized = 1;
> >
> > You need smp_wmb() before assigning 'kprobe_blacklist_initialized = 1'.
> > This guarantee that who see kprobe_blacklist_initialized = 1 will get
> > updated data of kprobe_blacklist.
>
> Right, to ensure blacklist is updated, memory barrier is required.
Agreed.
> > Please refer my previous patch once more :)
> >
> > And How about define kprobe_blacklist_initialized as boolean?
>
> Good idea :)
>
I'll fix it for v3.
-Oskar
>
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Re: Re: [PATCH v2 1/4] kprobes: delay blacklist symbol lookup until we actually need it
Thanks for your input guys!
On 04:16 Fri 05 Apr , Masami Hiramatsu wrote:
(2013/04/05 9:56), Joonsoo Kim wrote:
Hello, Oskar.
On Thu, Apr 04, 2013 at 02:51:26PM +0200, Oskar Andero wrote:
From: Toby Collett toby.coll...@sonymobile.com
The symbol lookup can take a long time and kprobes is
initialised very early in boot, so delay symbol lookup
until the blacklist is first used.
Cc: Masami Hiramatsu masami.hiramatsu...@hitachi.com
Cc: David S. Miller da...@davemloft.net
Reviewed-by: Radovan Lekanovic radovan.lekano...@sonymobile.com
Signed-off-by: Toby Collett toby.coll...@sonymobile.com
Signed-off-by: Oskar Andero oskar.and...@sonymobile.com
---
kernel/kprobes.c | 98
++--
1 file changed, 60 insertions(+), 38 deletions(-)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index e35be53..0a270e5 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -68,6 +68,7 @@
#endif
static int kprobes_initialized;
+static int kprobe_blacklist_initialized;
static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
@@ -102,6 +103,60 @@ static struct kprobe_blackpoint kprobe_blacklist[] = {
{NULL}/* Terminator */
};
+/* it can take some time ( 100ms ) to initialise the
+ * blacklist so we delay this until we actually need it
+ */
+static void init_kprobe_blacklist(void)
+{
+ int i;
+ unsigned long offset = 0, size = 0;
+ char *modname, namebuf[128];
+ const char *symbol_name;
+ void *addr;
+ struct kprobe_blackpoint *kb;
+
+ mutex_lock(kprobe_mutex);
+ if (kprobe_blacklist_initialized)
+ goto out;
+
+ /*
+ * Lookup and populate the kprobe_blacklist.
+ *
+ * Unlike the kretprobe blacklist, we'll need to determine
+ * the range of addresses that belong to the said functions,
+ * since a kprobe need not necessarily be at the beginning
+ * of a function.
+ */
+ for (kb = kprobe_blacklist; kb-name != NULL; kb++) {
+ kprobe_lookup_name(kb-name, addr);
+ if (!addr)
+ continue;
+
+ kb-start_addr = (unsigned long)addr;
+ symbol_name = kallsyms_lookup(kb-start_addr,
+ size, offset, modname, namebuf);
+ if (!symbol_name)
+ kb-range = 0;
+ else
+ kb-range = size;
+ }
+
+ if (kretprobe_blacklist_size) {
+ /* lookup the function address from its name */
+ for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
+ kprobe_lookup_name(kretprobe_blacklist[i].name,
+ kretprobe_blacklist[i].addr);
+ if (!kretprobe_blacklist[i].addr)
+ printk(kretprobe: lookup failed: %s\n,
+ kretprobe_blacklist[i].name);
+ }
+ }
+ kprobe_blacklist_initialized = 1;
You need smp_wmb() before assigning 'kprobe_blacklist_initialized = 1'.
This guarantee that who see kprobe_blacklist_initialized = 1 will get
updated data of kprobe_blacklist.
Right, to ensure blacklist is updated, memory barrier is required.
Agreed.
Please refer my previous patch once more :)
And How about define kprobe_blacklist_initialized as boolean?
Good idea :)
I'll fix it for v3.
-Oskar
--
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: Re: [PATCH v2 1/4] kprobes: delay blacklist symbol lookup until we actually need it
(2013/04/05 9:56), Joonsoo Kim wrote:
> Hello, Oskar.
>
> On Thu, Apr 04, 2013 at 02:51:26PM +0200, Oskar Andero wrote:
>> From: Toby Collett
>>
>> The symbol lookup can take a long time and kprobes is
>> initialised very early in boot, so delay symbol lookup
>> until the blacklist is first used.
>>
>> Cc: Masami Hiramatsu
>> Cc: David S. Miller
>> Reviewed-by: Radovan Lekanovic
>> Signed-off-by: Toby Collett
>> Signed-off-by: Oskar Andero
>> ---
>> kernel/kprobes.c | 98
>> ++--
>> 1 file changed, 60 insertions(+), 38 deletions(-)
>>
>> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
>> index e35be53..0a270e5 100644
>> --- a/kernel/kprobes.c
>> +++ b/kernel/kprobes.c
>> @@ -68,6 +68,7 @@
>> #endif
>>
>> static int kprobes_initialized;
>> +static int kprobe_blacklist_initialized;
>> static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
>> static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
>>
>> @@ -102,6 +103,60 @@ static struct kprobe_blackpoint kprobe_blacklist[] = {
>> {NULL}/* Terminator */
>> };
>>
>> +/* it can take some time ( > 100ms ) to initialise the
>> + * blacklist so we delay this until we actually need it
>> + */
>> +static void init_kprobe_blacklist(void)
>> +{
>> +int i;
>> +unsigned long offset = 0, size = 0;
>> +char *modname, namebuf[128];
>> +const char *symbol_name;
>> +void *addr;
>> +struct kprobe_blackpoint *kb;
>> +
>> +mutex_lock(_mutex);
>> +if (kprobe_blacklist_initialized)
>> +goto out;
>> +
>> +/*
>> + * Lookup and populate the kprobe_blacklist.
>> + *
>> + * Unlike the kretprobe blacklist, we'll need to determine
>> + * the range of addresses that belong to the said functions,
>> + * since a kprobe need not necessarily be at the beginning
>> + * of a function.
>> + */
>> +for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
>> +kprobe_lookup_name(kb->name, addr);
>> +if (!addr)
>> +continue;
>> +
>> +kb->start_addr = (unsigned long)addr;
>> +symbol_name = kallsyms_lookup(kb->start_addr,
>> +, , , namebuf);
>> +if (!symbol_name)
>> +kb->range = 0;
>> +else
>> +kb->range = size;
>> +}
>> +
>> +if (kretprobe_blacklist_size) {
>> +/* lookup the function address from its name */
>> +for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
>> +kprobe_lookup_name(kretprobe_blacklist[i].name,
>> + kretprobe_blacklist[i].addr);
>> +if (!kretprobe_blacklist[i].addr)
>> +printk("kretprobe: lookup failed: %s\n",
>> + kretprobe_blacklist[i].name);
>> +}
>> +}
>> +kprobe_blacklist_initialized = 1;
>
> You need smp_wmb() before assigning 'kprobe_blacklist_initialized = 1'.
> This guarantee that who see kprobe_blacklist_initialized = 1 will get
> updated data of kprobe_blacklist.
Right, to ensure blacklist is updated, memory barrier is required.
> Please refer my previous patch once more :)
>
> And How about define kprobe_blacklist_initialized as boolean?
Good idea :)
Thank you,
--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu...@hitachi.com
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: Re: [PATCH v2 1/4] kprobes: delay blacklist symbol lookup until we actually need it
(2013/04/05 9:56), Joonsoo Kim wrote:
Hello, Oskar.
On Thu, Apr 04, 2013 at 02:51:26PM +0200, Oskar Andero wrote:
From: Toby Collett toby.coll...@sonymobile.com
The symbol lookup can take a long time and kprobes is
initialised very early in boot, so delay symbol lookup
until the blacklist is first used.
Cc: Masami Hiramatsu masami.hiramatsu...@hitachi.com
Cc: David S. Miller da...@davemloft.net
Reviewed-by: Radovan Lekanovic radovan.lekano...@sonymobile.com
Signed-off-by: Toby Collett toby.coll...@sonymobile.com
Signed-off-by: Oskar Andero oskar.and...@sonymobile.com
---
kernel/kprobes.c | 98
++--
1 file changed, 60 insertions(+), 38 deletions(-)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index e35be53..0a270e5 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -68,6 +68,7 @@
#endif
static int kprobes_initialized;
+static int kprobe_blacklist_initialized;
static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
@@ -102,6 +103,60 @@ static struct kprobe_blackpoint kprobe_blacklist[] = {
{NULL}/* Terminator */
};
+/* it can take some time ( 100ms ) to initialise the
+ * blacklist so we delay this until we actually need it
+ */
+static void init_kprobe_blacklist(void)
+{
+int i;
+unsigned long offset = 0, size = 0;
+char *modname, namebuf[128];
+const char *symbol_name;
+void *addr;
+struct kprobe_blackpoint *kb;
+
+mutex_lock(kprobe_mutex);
+if (kprobe_blacklist_initialized)
+goto out;
+
+/*
+ * Lookup and populate the kprobe_blacklist.
+ *
+ * Unlike the kretprobe blacklist, we'll need to determine
+ * the range of addresses that belong to the said functions,
+ * since a kprobe need not necessarily be at the beginning
+ * of a function.
+ */
+for (kb = kprobe_blacklist; kb-name != NULL; kb++) {
+kprobe_lookup_name(kb-name, addr);
+if (!addr)
+continue;
+
+kb-start_addr = (unsigned long)addr;
+symbol_name = kallsyms_lookup(kb-start_addr,
+size, offset, modname, namebuf);
+if (!symbol_name)
+kb-range = 0;
+else
+kb-range = size;
+}
+
+if (kretprobe_blacklist_size) {
+/* lookup the function address from its name */
+for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
+kprobe_lookup_name(kretprobe_blacklist[i].name,
+ kretprobe_blacklist[i].addr);
+if (!kretprobe_blacklist[i].addr)
+printk(kretprobe: lookup failed: %s\n,
+ kretprobe_blacklist[i].name);
+}
+}
+kprobe_blacklist_initialized = 1;
You need smp_wmb() before assigning 'kprobe_blacklist_initialized = 1'.
This guarantee that who see kprobe_blacklist_initialized = 1 will get
updated data of kprobe_blacklist.
Right, to ensure blacklist is updated, memory barrier is required.
Please refer my previous patch once more :)
And How about define kprobe_blacklist_initialized as boolean?
Good idea :)
Thank you,
--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu...@hitachi.com
--
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
