By extracting mcount sorting code and sort them earliler, futher patches
will be able to determine whether an address is on an ftrace entry or
not using bsearch().
ftrace_sort_mcount_area() will be called before, during and after
ftrace_init (when module insertion). Ensure it sort kernel mcount table
only once.
Signed-off-by: Wang Nan <wangn...@huawei.com>
---
include/linux/ftrace.h | 2 ++
init/main.c | 1 +
kernel/trace/ftrace.c | 38 ++++++++++++++++++++++++++++++++++++--
3 files changed, 39 insertions(+), 2 deletions(-)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 1da6029..8db315a 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -701,8 +701,10 @@ static inline void __ftrace_enabled_restore(int enabled)
#ifdef CONFIG_FTRACE_MCOUNT_RECORD
extern void ftrace_init(void);
+extern void ftrace_init_early(void);
#else
static inline void ftrace_init(void) { }
+static inline void ftrace_init_early(void) { }
#endif
/*
diff --git a/init/main.c b/init/main.c
index 6f0f1c5f..eaafc3e 100644
--- a/init/main.c
+++ b/init/main.c
@@ -517,6 +517,7 @@ asmlinkage __visible void __init start_kernel(void)
boot_cpu_init();
page_address_init();
pr_notice("%s", linux_banner);
+ ftrace_init_early();
setup_arch(&command_line);
mm_init_cpumask(&init_mm);
setup_command_line(command_line);
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 6c6cbb1..a75cfbe 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1169,6 +1169,7 @@ struct ftrace_page {
static struct ftrace_page *ftrace_pages_start;
static struct ftrace_page *ftrace_pages;
+static bool kernel_mcount_sorted = false;
static bool __always_inline ftrace_hash_empty(struct ftrace_hash *hash)
{
@@ -4743,6 +4744,32 @@ static void ftrace_swap_ips(void *a, void *b, int size)
*ipb = t;
}
+static void ftrace_sort_mcount_area(unsigned long *start, unsigned long *end)
+{
+ extern unsigned long __start_mcount_loc[];
+ extern unsigned long __stop_mcount_loc[];
+
+ unsigned long count;
+ bool is_kernel_mcount;
+
+ count = end - start;
+ if (!count)
+ return;
+
+ is_kernel_mcount =
+ (start == __start_mcount_loc) &&
+ (end == __stop_mcount_loc);
+
+ if (is_kernel_mcount && kernel_mcount_sorted)
+ return;
+
+ sort(start, count, sizeof(*start),
+ ftrace_cmp_ips, ftrace_swap_ips);
+
+ if (is_kernel_mcount)
+ kernel_mcount_sorted = true;
+}
+
static int ftrace_process_locs(struct module *mod,
unsigned long *start,
unsigned long *end)
@@ -4761,8 +4788,7 @@ static int ftrace_process_locs(struct module *mod,
if (!count)
return 0;
- sort(start, count, sizeof(*start),
- ftrace_cmp_ips, ftrace_swap_ips);
+ ftrace_sort_mcount_area(start, end);
start_pg = ftrace_allocate_pages(count);
if (!start_pg)
@@ -4965,6 +4991,14 @@ void __init ftrace_init(void)
ftrace_disabled = 1;
}
+void __init ftrace_init_early(void)
+{
+ extern unsigned long __start_mcount_loc[];
+ extern unsigned long __stop_mcount_loc[];
+
+ ftrace_sort_mcount_area(__start_mcount_loc, __stop_mcount_loc);
+}
+
/* Do nothing if arch does not support this */
void __weak arch_ftrace_update_trampoline(struct ftrace_ops *ops)
{
--
1.8.4
--
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