summaryrefslogtreecommitdiffstats
path: root/kernel/trace/ftrace.c
diff options
context:
space:
mode:
authorSteven Rostedt <srostedt@redhat.com>2008-11-15 01:21:19 +0100
committerIngo Molnar <mingo@elte.hu>2008-11-16 07:36:02 +0100
commit31e889098a80ceb3e9e3c555d522b2686a6663c6 (patch)
tree2acb73507de4191d4a9aa5ccf08fa24e7044c89e /kernel/trace/ftrace.c
parentftrace: replace raw_local_irq_save with local_irq_save (diff)
downloadlinux-31e889098a80ceb3e9e3c555d522b2686a6663c6.tar.xz
linux-31e889098a80ceb3e9e3c555d522b2686a6663c6.zip
ftrace: pass module struct to arch dynamic ftrace functions
Impact: allow archs more flexibility on dynamic ftrace implementations Dynamic ftrace has largly been developed on x86. Since x86 does not have the same limitations as other architectures, the ftrace interaction between the generic code and the architecture specific code was not flexible enough to handle some of the issues that other architectures have. Most notably, module trampolines. Due to the limited branch distance that archs make in calling kernel core code from modules, the module load code must create a trampoline to jump to what will make the larger jump into core kernel code. The problem arises when this happens to a call to mcount. Ftrace checks all code before modifying it and makes sure the current code is what it expects. Right now, there is not enough information to handle modifying module trampolines. This patch changes the API between generic dynamic ftrace code and the arch dependent code. There is now two functions for modifying code: ftrace_make_nop(mod, rec, addr) - convert the code at rec->ip into a nop, where the original text is calling addr. (mod is the module struct if called by module init) ftrace_make_caller(rec, addr) - convert the code rec->ip that should be a nop into a caller to addr. The record "rec" now has a new field called "arch" where the architecture can add any special attributes to each call site record. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/trace/ftrace.c')
-rw-r--r--kernel/trace/ftrace.c62
1 files changed, 24 insertions, 38 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 3940c71ac2a2..e9a5fbfce08e 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -358,9 +358,7 @@ static void print_ip_ins(const char *fmt, unsigned char *p)
printk(KERN_CONT "%s%02x", i ? ":" : "", p[i]);
}
-static void ftrace_bug(int failed, unsigned long ip,
- unsigned char *expected,
- unsigned char *replace)
+static void ftrace_bug(int failed, unsigned long ip)
{
switch (failed) {
case -EFAULT:
@@ -372,9 +370,7 @@ static void ftrace_bug(int failed, unsigned long ip,
FTRACE_WARN_ON_ONCE(1);
pr_info("ftrace failed to modify ");
print_ip_sym(ip);
- print_ip_ins(" expected: ", expected);
print_ip_ins(" actual: ", (unsigned char *)ip);
- print_ip_ins(" replace: ", replace);
printk(KERN_CONT "\n");
break;
case -EPERM:
@@ -392,8 +388,7 @@ static void ftrace_bug(int failed, unsigned long ip,
#define FTRACE_ADDR ((long)(ftrace_caller))
static int
-__ftrace_replace_code(struct dyn_ftrace *rec,
- unsigned char *old, unsigned char *new, int enable)
+__ftrace_replace_code(struct dyn_ftrace *rec, int enable)
{
unsigned long ip, fl;
@@ -435,12 +430,10 @@ __ftrace_replace_code(struct dyn_ftrace *rec,
* otherwise enable it!
*/
if (fl & FTRACE_FL_ENABLED) {
- /* swap new and old */
- new = old;
- old = ftrace_call_replace(ip, FTRACE_ADDR);
+ enable = 0;
rec->flags &= ~FTRACE_FL_ENABLED;
} else {
- new = ftrace_call_replace(ip, FTRACE_ADDR);
+ enable = 1;
rec->flags |= FTRACE_FL_ENABLED;
}
} else {
@@ -453,10 +446,7 @@ __ftrace_replace_code(struct dyn_ftrace *rec,
fl = rec->flags & (FTRACE_FL_NOTRACE | FTRACE_FL_ENABLED);
if (fl == FTRACE_FL_NOTRACE)
return 0;
-
- new = ftrace_call_replace(ip, FTRACE_ADDR);
- } else
- old = ftrace_call_replace(ip, FTRACE_ADDR);
+ }
if (enable) {
if (rec->flags & FTRACE_FL_ENABLED)
@@ -469,21 +459,18 @@ __ftrace_replace_code(struct dyn_ftrace *rec,
}
}
- return ftrace_modify_code(ip, old, new);
+ if (enable)
+ return ftrace_make_call(rec, FTRACE_ADDR);
+ else
+ return ftrace_make_nop(NULL, rec, FTRACE_ADDR);
}
static void ftrace_replace_code(int enable)
{
int i, failed;
- unsigned char *new = NULL, *old = NULL;
struct dyn_ftrace *rec;
struct ftrace_page *pg;
- if (enable)
- old = ftrace_nop_replace();
- else
- new = ftrace_nop_replace();
-
for (pg = ftrace_pages_start; pg; pg = pg->next) {
for (i = 0; i < pg->index; i++) {
rec = &pg->records[i];
@@ -504,34 +491,30 @@ static void ftrace_replace_code(int enable)
unfreeze_record(rec);
}
- failed = __ftrace_replace_code(rec, old, new, enable);
+ failed = __ftrace_replace_code(rec, enable);
if (failed && (rec->flags & FTRACE_FL_CONVERTED)) {
rec->flags |= FTRACE_FL_FAILED;
if ((system_state == SYSTEM_BOOTING) ||
!core_kernel_text(rec->ip)) {
ftrace_free_rec(rec);
} else
- ftrace_bug(failed, rec->ip, old, new);
+ ftrace_bug(failed, rec->ip);
}
}
}
}
static int
-ftrace_code_disable(struct dyn_ftrace *rec)
+ftrace_code_disable(struct module *mod, struct dyn_ftrace *rec)
{
unsigned long ip;
- unsigned char *nop, *call;
int ret;
ip = rec->ip;
- nop = ftrace_nop_replace();
- call = ftrace_call_replace(ip, mcount_addr);
-
- ret = ftrace_modify_code(ip, call, nop);
+ ret = ftrace_make_nop(mod, rec, mcount_addr);
if (ret) {
- ftrace_bug(ret, ip, call, nop);
+ ftrace_bug(ret, ip);
rec->flags |= FTRACE_FL_FAILED;
return 0;
}
@@ -650,7 +633,7 @@ static cycle_t ftrace_update_time;
static unsigned long ftrace_update_cnt;
unsigned long ftrace_update_tot_cnt;
-static int ftrace_update_code(void)
+static int ftrace_update_code(struct module *mod)
{
struct dyn_ftrace *p, *t;
cycle_t start, stop;
@@ -667,7 +650,7 @@ static int ftrace_update_code(void)
list_del_init(&p->list);
/* convert record (i.e, patch mcount-call with NOP) */
- if (ftrace_code_disable(p)) {
+ if (ftrace_code_disable(mod, p)) {
p->flags |= FTRACE_FL_CONVERTED;
ftrace_update_cnt++;
} else
@@ -1309,7 +1292,8 @@ static __init int ftrace_init_debugfs(void)
fs_initcall(ftrace_init_debugfs);
-static int ftrace_convert_nops(unsigned long *start,
+static int ftrace_convert_nops(struct module *mod,
+ unsigned long *start,
unsigned long *end)
{
unsigned long *p;
@@ -1325,18 +1309,19 @@ static int ftrace_convert_nops(unsigned long *start,
/* disable interrupts to prevent kstop machine */
local_irq_save(flags);
- ftrace_update_code();
+ ftrace_update_code(mod);
local_irq_restore(flags);
mutex_unlock(&ftrace_start_lock);
return 0;
}
-void ftrace_init_module(unsigned long *start, unsigned long *end)
+void ftrace_init_module(struct module *mod,
+ unsigned long *start, unsigned long *end)
{
if (ftrace_disabled || start == end)
return;
- ftrace_convert_nops(start, end);
+ ftrace_convert_nops(mod, start, end);
}
extern unsigned long __start_mcount_loc[];
@@ -1366,7 +1351,8 @@ void __init ftrace_init(void)
last_ftrace_enabled = ftrace_enabled = 1;
- ret = ftrace_convert_nops(__start_mcount_loc,
+ ret = ftrace_convert_nops(NULL,
+ __start_mcount_loc,
__stop_mcount_loc);
return;