[RFC PATCH v2 07/26] ftrace: allow search ftrace addr before ftrace fully inited.

From: Wang Nan
Date: Thu Feb 12 2015 - 07:34:07 EST


Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
---
kernel/trace/ftrace.c | 38 ++++++++++++++++++++++++++++++++++++++
1 file changed, 38 insertions(+)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index a6a6b09..79b3e88 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1539,6 +1539,8 @@ static unsigned long ftrace_location_range(unsigned long start, unsigned long en
return 0;
}

+static unsigned long ftrace_search_mcount_ip(unsigned long ip);
+
/**
* ftrace_location - return true if the ip giving is a traced location
* @ip: the instruction pointer to check
@@ -1550,6 +1552,9 @@ static unsigned long ftrace_location_range(unsigned long start, unsigned long en
*/
unsigned long ftrace_location(unsigned long ip)
{
+ if (unlikely(!ftrace_pages_start))
+ return ftrace_search_mcount_ip(ip);
+
return ftrace_location_range(ip, ip);
}

@@ -4733,6 +4738,18 @@ static int ftrace_cmp_ips(const void *a, const void *b)
return 0;
}

+static int ftrace_cmp_ips_insn(const void *a, const void *b)
+{
+ const unsigned long *ipa = a;
+ const unsigned long *ipb = b;
+
+ if (*ipa >= *ipb + MCOUNT_INSN_SIZE)
+ return 1;
+ if (*ipa < *ipb)
+ return -1;
+ return 0;
+}
+
static void ftrace_swap_ips(void *a, void *b, int size)
{
unsigned long *ipa = a;
@@ -4764,6 +4781,27 @@ static void ftrace_sort_mcount_area(void)
}
}

+static unsigned long ftrace_search_mcount_ip(unsigned long ip)
+{
+ extern unsigned long __start_mcount_loc[];
+ extern unsigned long __stop_mcount_loc[];
+
+ unsigned long *mcount_start = __start_mcount_loc;
+ unsigned long *mcount_end = __stop_mcount_loc;
+ unsigned long count = mcount_end - mcount_start;
+ unsigned long *retval;
+
+ if (!mcount_sorted)
+ return 0;
+
+ retval = bsearch(&ip, mcount_start, count,
+ sizeof(unsigned long), ftrace_cmp_ips_insn);
+ if (!retval)
+ return 0;
+
+ return ftrace_call_adjust(ip);
+}
+
static int ftrace_process_locs(struct module *mod,
unsigned long *start,
unsigned long *end)
--
1.8.4

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