| Message ID | 1513554812-13014-4-git-send-email-me@tobin.cc (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, 18 Dec 2017 10:53:32 +1100 "Tobin C. Harding" <me@tobin.cc> wrote: > Fixes behaviour modified by: commit bd6b239cdbb2 ("kallsyms: don't leak > address when symbol not found") > > Previous patch changed behaviour of kallsyms function sprint_symbol() to > return an error code instead of printing the address if a symbol was not > found. Ftrace relies on the original behaviour. We should not break > tracing when applying the previous patch. We can maintain the original > behaviour by checking the return code on calls to sprint_symbol() and > friends. > > Check return code and print actual address on error (i.e symbol not > found). > > Signed-off-by: Tobin C. Harding <me@tobin.cc> > --- > kernel/trace/trace.h | 24 ++++++++++++++++++++++++ > kernel/trace/trace_events_hist.c | 6 +++--- > 2 files changed, 27 insertions(+), 3 deletions(-) > > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h > index 2a6d0325a761..881b1a577d75 100644 > --- a/kernel/trace/trace.h > +++ b/kernel/trace/trace.h > @@ -1814,4 +1814,28 @@ static inline void trace_event_eval_update(struct trace_eval_map **map, int len) > > extern struct trace_iterator *tracepoint_print_iter; > > +static inline int > +trace_sprint_symbol(char *buffer, unsigned long address) > +{ > + int ret; > + > + ret = sprint_symbol(buffer, address); > + if (ret == -1) > + ret = sprintf(buffer, "0x%lx", address); > + > + return ret; > +} > + > +static inline int > +trace_sprint_symbol_no_offset(char *buffer, unsigned long address) > +{ > + int ret; > + > + ret = sprint_symbol_no_offset(buffer, address); > + if (ret == -1) > + ret = sprintf(buffer, "0x%lx", address); > + > + return ret; > +} > + > #endif /* _LINUX_KERNEL_TRACE_H */ > diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c > index 1e1558c99d56..3e28522a76f4 100644 > --- a/kernel/trace/trace_events_hist.c > +++ b/kernel/trace/trace_events_hist.c > @@ -982,7 +982,7 @@ static void hist_trigger_stacktrace_print(struct seq_file *m, > return; > > seq_printf(m, "%*c", 1 + spaces, ' '); > - sprint_symbol(str, stacktrace_entries[i]); > + trace_sprint_symbol_addr(str, stacktrace_entries[i]); Hmm, where is trace_sprint_symbol_addr() defined? -- Steve > seq_printf(m, "%s\n", str); > } > } > @@ -1014,12 +1014,12 @@ hist_trigger_entry_print(struct seq_file *m, > seq_printf(m, "%s: %llx", field_name, uval); > } else if (key_field->flags & HIST_FIELD_FL_SYM) { > uval = *(u64 *)(key + key_field->offset); > - sprint_symbol_no_offset(str, uval); > + trace_sprint_symbol_no_offset(str, uval); > seq_printf(m, "%s: [%llx] %-45s", field_name, > uval, str); > } else if (key_field->flags & HIST_FIELD_FL_SYM_OFFSET) { > uval = *(u64 *)(key + key_field->offset); > - sprint_symbol(str, uval); > + trace_sprint_symbol(str, uval); > seq_printf(m, "%s: [%llx] %-55s", field_name, > uval, str); > } else if (key_field->flags & HIST_FIELD_FL_EXECNAME) {
On Mon, Dec 18, 2017 at 11:49:47AM -0500, Steven Rostedt wrote: > On Mon, 18 Dec 2017 10:53:32 +1100 > "Tobin C. Harding" <me@tobin.cc> wrote: > > > Fixes behaviour modified by: commit bd6b239cdbb2 ("kallsyms: don't leak > > address when symbol not found") > > > > Previous patch changed behaviour of kallsyms function sprint_symbol() to > > return an error code instead of printing the address if a symbol was not > > found. Ftrace relies on the original behaviour. We should not break > > tracing when applying the previous patch. We can maintain the original > > behaviour by checking the return code on calls to sprint_symbol() and > > friends. > > > > Check return code and print actual address on error (i.e symbol not > > found). > > > > Signed-off-by: Tobin C. Harding <me@tobin.cc> > > --- > > kernel/trace/trace.h | 24 ++++++++++++++++++++++++ > > kernel/trace/trace_events_hist.c | 6 +++--- > > 2 files changed, 27 insertions(+), 3 deletions(-) > > > > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h > > index 2a6d0325a761..881b1a577d75 100644 > > --- a/kernel/trace/trace.h > > +++ b/kernel/trace/trace.h > > @@ -1814,4 +1814,28 @@ static inline void trace_event_eval_update(struct trace_eval_map **map, int len) > > > > extern struct trace_iterator *tracepoint_print_iter; > > > > +static inline int > > +trace_sprint_symbol(char *buffer, unsigned long address) > > +{ > > + int ret; > > + > > + ret = sprint_symbol(buffer, address); > > + if (ret == -1) > > + ret = sprintf(buffer, "0x%lx", address); > > + > > + return ret; > > +} > > + > > +static inline int > > +trace_sprint_symbol_no_offset(char *buffer, unsigned long address) > > +{ > > + int ret; > > + > > + ret = sprint_symbol_no_offset(buffer, address); > > + if (ret == -1) > > + ret = sprintf(buffer, "0x%lx", address); > > + > > + return ret; > > +} > > + > > #endif /* _LINUX_KERNEL_TRACE_H */ > > diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c > > index 1e1558c99d56..3e28522a76f4 100644 > > --- a/kernel/trace/trace_events_hist.c > > +++ b/kernel/trace/trace_events_hist.c > > @@ -982,7 +982,7 @@ static void hist_trigger_stacktrace_print(struct seq_file *m, > > return; > > > > seq_printf(m, "%*c", 1 + spaces, ' '); > > - sprint_symbol(str, stacktrace_entries[i]); > > + trace_sprint_symbol_addr(str, stacktrace_entries[i]); > > Hmm, where is trace_sprint_symbol_addr() defined? Gee, seems I can't build a kernel and I can't read a diff - epic fail. Sorry for wasting your time Steve I'll try to be more careful. FTR This should have been - sprint_symbol(str, stacktrace_entries[i]); + trace_sprint_symbol(str, stacktrace_entries[i]); If you have the time to give me some brief pointers on how I should go about testing this I'd love to test it before the next version. I know very little about ftrace. thanks, Tobin.
On Mon, Dec 18, 2017 at 11:49:47AM -0500, Steven Rostedt wrote: > On Mon, 18 Dec 2017 10:53:32 +1100 > "Tobin C. Harding" <me@tobin.cc> wrote: > > > Fixes behaviour modified by: commit bd6b239cdbb2 ("kallsyms: don't leak > > address when symbol not found") > > > > Previous patch changed behaviour of kallsyms function sprint_symbol() to > > return an error code instead of printing the address if a symbol was not > > found. Ftrace relies on the original behaviour. We should not break > > tracing when applying the previous patch. We can maintain the original > > behaviour by checking the return code on calls to sprint_symbol() and > > friends. > > > > Check return code and print actual address on error (i.e symbol not > > found). > > > > Signed-off-by: Tobin C. Harding <me@tobin.cc> > > --- > > kernel/trace/trace.h | 24 ++++++++++++++++++++++++ > > kernel/trace/trace_events_hist.c | 6 +++--- > > 2 files changed, 27 insertions(+), 3 deletions(-) > > > > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h > > index 2a6d0325a761..881b1a577d75 100644 > > --- a/kernel/trace/trace.h > > +++ b/kernel/trace/trace.h > > @@ -1814,4 +1814,28 @@ static inline void trace_event_eval_update(struct trace_eval_map **map, int len) > > > > extern struct trace_iterator *tracepoint_print_iter; > > > > +static inline int > > +trace_sprint_symbol(char *buffer, unsigned long address) > > +{ > > + int ret; > > + > > + ret = sprint_symbol(buffer, address); > > + if (ret == -1) > > + ret = sprintf(buffer, "0x%lx", address); > > + > > + return ret; > > +} > > + > > +static inline int > > +trace_sprint_symbol_no_offset(char *buffer, unsigned long address) > > +{ > > + int ret; > > + > > + ret = sprint_symbol_no_offset(buffer, address); > > + if (ret == -1) > > + ret = sprintf(buffer, "0x%lx", address); > > + > > + return ret; > > +} > > + > > #endif /* _LINUX_KERNEL_TRACE_H */ > > diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c > > index 1e1558c99d56..3e28522a76f4 100644 > > --- a/kernel/trace/trace_events_hist.c > > +++ b/kernel/trace/trace_events_hist.c > > @@ -982,7 +982,7 @@ static void hist_trigger_stacktrace_print(struct seq_file *m, > > return; > > > > seq_printf(m, "%*c", 1 + spaces, ' '); > > - sprint_symbol(str, stacktrace_entries[i]); > > + trace_sprint_symbol_addr(str, stacktrace_entries[i]); > > Hmm, where is trace_sprint_symbol_addr() defined? > > -- Steve Also, I missed one in kernel/trace/trace_output.c Added for next version. thanks, Tobin.
On Tue, 19 Dec 2017 08:16:14 +1100 "Tobin C. Harding" <me@tobin.cc> wrote: > > > #endif /* _LINUX_KERNEL_TRACE_H */ > > > diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c > > > index 1e1558c99d56..3e28522a76f4 100644 > > > --- a/kernel/trace/trace_events_hist.c > > > +++ b/kernel/trace/trace_events_hist.c > > > @@ -982,7 +982,7 @@ static void hist_trigger_stacktrace_print(struct seq_file *m, > > > return; > > > > > > seq_printf(m, "%*c", 1 + spaces, ' '); > > > - sprint_symbol(str, stacktrace_entries[i]); > > > + trace_sprint_symbol_addr(str, stacktrace_entries[i]); > > > > If you have the time to give me some brief pointers on how I should go > about testing this I'd love to test it before the next version. I know > very little about ftrace. For hitting the histogram stacktrace trigger (this code path), make sure you have CONFIG_HIST_TRIGGERS enabled. And then do: # cd /sys/kernel/debug/tracing # echo 'hist:keys=common_pid.execname,stacktrace:vals=prev_state' > \ events/sched/sched_switch/trigger # cat events/sched/sched_switch/hist For the "sym" part, you can do (from the same directory): # echo 'hist:keys=call_site.sym:vals=bytes_req' > \ events/kmem/kmalloc/trigger # cat events/kmem/kmalloc/hist And for sym-offset: # echo 'hist:keys=call_site.sym-offset:vals=bytes_req' > \ events/kmem/kmalloc/trigger # cat events/kmem/kmalloc/hist -- Steve
On Mon, Dec 18, 2017 at 06:51:43PM -0500, Steven Rostedt wrote: > On Tue, 19 Dec 2017 08:16:14 +1100 > "Tobin C. Harding" <me@tobin.cc> wrote: > > > > > #endif /* _LINUX_KERNEL_TRACE_H */ > > > > diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c > > > > index 1e1558c99d56..3e28522a76f4 100644 > > > > --- a/kernel/trace/trace_events_hist.c > > > > +++ b/kernel/trace/trace_events_hist.c > > > > @@ -982,7 +982,7 @@ static void hist_trigger_stacktrace_print(struct seq_file *m, > > > > return; > > > > > > > > seq_printf(m, "%*c", 1 + spaces, ' '); > > > > - sprint_symbol(str, stacktrace_entries[i]); > > > > + trace_sprint_symbol_addr(str, stacktrace_entries[i]); > > > > > > > > If you have the time to give me some brief pointers on how I should go > > about testing this I'd love to test it before the next version. I know > > very little about ftrace. > > For hitting the histogram stacktrace trigger (this code path), make > sure you have CONFIG_HIST_TRIGGERS enabled. And then do: > > # cd /sys/kernel/debug/tracing > # echo 'hist:keys=common_pid.execname,stacktrace:vals=prev_state' > \ > events/sched/sched_switch/trigger > # cat events/sched/sched_switch/hist > > For the "sym" part, you can do (from the same directory): > > # echo 'hist:keys=call_site.sym:vals=bytes_req' > \ > events/kmem/kmalloc/trigger > # cat events/kmem/kmalloc/hist > > > And for sym-offset: > > # echo 'hist:keys=call_site.sym-offset:vals=bytes_req' > \ > events/kmem/kmalloc/trigger > # cat events/kmem/kmalloc/hist > > -- Steve Thanks, you're the man
On Mon, Dec 18, 2017 at 06:51:43PM -0500, Steven Rostedt wrote: > On Tue, 19 Dec 2017 08:16:14 +1100 > "Tobin C. Harding" <me@tobin.cc> wrote: > > > > > #endif /* _LINUX_KERNEL_TRACE_H */ > > > > diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c > > > > index 1e1558c99d56..3e28522a76f4 100644 > > > > --- a/kernel/trace/trace_events_hist.c > > > > +++ b/kernel/trace/trace_events_hist.c > > > > @@ -982,7 +982,7 @@ static void hist_trigger_stacktrace_print(struct seq_file *m, > > > > return; > > > > > > > > seq_printf(m, "%*c", 1 + spaces, ' '); > > > > - sprint_symbol(str, stacktrace_entries[i]); > > > > + trace_sprint_symbol_addr(str, stacktrace_entries[i]); > > > > > > > > If you have the time to give me some brief pointers on how I should go > > about testing this I'd love to test it before the next version. I know > > very little about ftrace. > > For hitting the histogram stacktrace trigger (this code path), make > sure you have CONFIG_HIST_TRIGGERS enabled. And then do: > > # cd /sys/kernel/debug/tracing > # echo 'hist:keys=common_pid.execname,stacktrace:vals=prev_state' > \ > events/sched/sched_switch/trigger > # cat events/sched/sched_switch/hist > > For the "sym" part, you can do (from the same directory): > > # echo 'hist:keys=call_site.sym:vals=bytes_req' > \ > events/kmem/kmalloc/trigger > # cat events/kmem/kmalloc/hist > > > And for sym-offset: > > # echo 'hist:keys=call_site.sym-offset:vals=bytes_req' > \ > events/kmem/kmalloc/trigger > # cat events/kmem/kmalloc/hist I ran through these as outlined here for the new version (v4). This hits the modified code but doesn't test symbol look up failure. I also configured kernel with 'Perform a startup test on ftrace' for good luck. Are you happy with this level of testing? thanks, Tobin.
On Tue, Dec 19, 2017 at 02:00:11PM +1100, Tobin C. Harding wrote: > On Mon, Dec 18, 2017 at 06:51:43PM -0500, Steven Rostedt wrote: > > On Tue, 19 Dec 2017 08:16:14 +1100 > > "Tobin C. Harding" <me@tobin.cc> wrote: > > > > > > > #endif /* _LINUX_KERNEL_TRACE_H */ > > > > > diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c > > > > > index 1e1558c99d56..3e28522a76f4 100644 > > > > > --- a/kernel/trace/trace_events_hist.c > > > > > +++ b/kernel/trace/trace_events_hist.c > > > > > @@ -982,7 +982,7 @@ static void hist_trigger_stacktrace_print(struct seq_file *m, > > > > > return; > > > > > > > > > > seq_printf(m, "%*c", 1 + spaces, ' '); > > > > > - sprint_symbol(str, stacktrace_entries[i]); > > > > > + trace_sprint_symbol_addr(str, stacktrace_entries[i]); > > > > > > > > > > > > If you have the time to give me some brief pointers on how I should go > > > about testing this I'd love to test it before the next version. I know > > > very little about ftrace. > > > > For hitting the histogram stacktrace trigger (this code path), make > > sure you have CONFIG_HIST_TRIGGERS enabled. And then do: > > > > # cd /sys/kernel/debug/tracing > > # echo 'hist:keys=common_pid.execname,stacktrace:vals=prev_state' > \ > > events/sched/sched_switch/trigger > > # cat events/sched/sched_switch/hist > > > > For the "sym" part, you can do (from the same directory): > > > > # echo 'hist:keys=call_site.sym:vals=bytes_req' > \ > > events/kmem/kmalloc/trigger > > # cat events/kmem/kmalloc/hist > > > > > > And for sym-offset: > > > > # echo 'hist:keys=call_site.sym-offset:vals=bytes_req' > \ > > events/kmem/kmalloc/trigger > > # cat events/kmem/kmalloc/hist > > I ran through these as outlined here for the new version (v4). This hits Should have been: v2 thanks, Tobin.
On Tue, 19 Dec 2017 14:00:11 +1100 "Tobin C. Harding" <me@tobin.cc> wrote: > I ran through these as outlined here for the new version (v4). This hits > the modified code but doesn't test symbol look up failure. stacktrace shouldn't post non kernel values, unless there's a frame pointer that isn't handled by kallsyms. As for the other two, we could probably force a failure, like: # echo 'hist:keys=hrtimer.sym' > \ events/timer/hrtimer_start/trigger # cat events/timer/hrtimer_start/hist And then just add sym-offset too. > > I also configured kernel with 'Perform a startup test on ftrace' for > good luck. > > Are you happy with this level of testing? Can you try the above. -- Steve
On Mon, Dec 18, 2017 at 10:37:38PM -0500, Steven Rostedt wrote: > On Tue, 19 Dec 2017 14:00:11 +1100 > "Tobin C. Harding" <me@tobin.cc> wrote: > > > I ran through these as outlined here for the new version (v4). This hits > > the modified code but doesn't test symbol look up failure. > > stacktrace shouldn't post non kernel values, unless there's a frame > pointer that isn't handled by kallsyms. > > As for the other two, we could probably force a failure, like: > > # echo 'hist:keys=hrtimer.sym' > \ > events/timer/hrtimer_start/trigger > # cat events/timer/hrtimer_start/hist > > And then just add sym-offset too. > > > I also configured kernel with 'Perform a startup test on ftrace' for > > good luck. > > > > Are you happy with this level of testing? > > Can you try the above. Did both and in both cases we get the addresses as hoped :) thanks, Tobin.
Hi Tobin,
I love your patch! Yet something to improve:
[auto build test ERROR on linus/master]
[also build test ERROR on v4.15-rc4 next-20171219]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Tobin-C-Harding/kallsyms-don-t-leak-address/20171220-062707
config: i386-randconfig-x016-201751 (attached as .config)
compiler: gcc-7 (Debian 7.2.0-12) 7.2.1 20171025
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
All errors (new ones prefixed by >>):
kernel/trace/trace_events_hist.c: In function 'hist_trigger_stacktrace_print':
>> kernel/trace/trace_events_hist.c:985:3: error: implicit declaration of function 'trace_sprint_symbol_addr'; did you mean 'trace_sprint_symbol'? [-Werror=implicit-function-declaration]
trace_sprint_symbol_addr(str, stacktrace_entries[i]);
^~~~~~~~~~~~~~~~~~~~~~~~
trace_sprint_symbol
cc1: some warnings being treated as errors
vim +985 kernel/trace/trace_events_hist.c
971
972 static void hist_trigger_stacktrace_print(struct seq_file *m,
973 unsigned long *stacktrace_entries,
974 unsigned int max_entries)
975 {
976 char str[KSYM_SYMBOL_LEN];
977 unsigned int spaces = 8;
978 unsigned int i;
979
980 for (i = 0; i < max_entries; i++) {
981 if (stacktrace_entries[i] == ULONG_MAX)
982 return;
983
984 seq_printf(m, "%*c", 1 + spaces, ' ');
> 985 trace_sprint_symbol_addr(str, stacktrace_entries[i]);
986 seq_printf(m, "%s\n", str);
987 }
988 }
989
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
Hi Tobin,
I love your patch! Yet something to improve:
[auto build test ERROR on linus/master]
[also build test ERROR on v4.15-rc4 next-20171219]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Tobin-C-Harding/kallsyms-don-t-leak-address/20171220-062707
config: i386-randconfig-s1-201751 (attached as .config)
compiler: gcc-6 (Debian 6.4.0-9) 6.4.0 20171026
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
All errors (new ones prefixed by >>):
kernel/trace/trace_events_hist.c: In function 'hist_trigger_stacktrace_print':
>> kernel/trace/trace_events_hist.c:985:3: error: implicit declaration of function 'trace_sprint_symbol_addr' [-Werror=implicit-function-declaration]
trace_sprint_symbol_addr(str, stacktrace_entries[i]);
^~~~~~~~~~~~~~~~~~~~~~~~
cc1: some warnings being treated as errors
vim +/trace_sprint_symbol_addr +985 kernel/trace/trace_events_hist.c
971
972 static void hist_trigger_stacktrace_print(struct seq_file *m,
973 unsigned long *stacktrace_entries,
974 unsigned int max_entries)
975 {
976 char str[KSYM_SYMBOL_LEN];
977 unsigned int spaces = 8;
978 unsigned int i;
979
980 for (i = 0; i < max_entries; i++) {
981 if (stacktrace_entries[i] == ULONG_MAX)
982 return;
983
984 seq_printf(m, "%*c", 1 + spaces, ' ');
> 985 trace_sprint_symbol_addr(str, stacktrace_entries[i]);
986 seq_printf(m, "%s\n", str);
987 }
988 }
989
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 2a6d0325a761..881b1a577d75 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1814,4 +1814,28 @@ static inline void trace_event_eval_update(struct trace_eval_map **map, int len) extern struct trace_iterator *tracepoint_print_iter; +static inline int +trace_sprint_symbol(char *buffer, unsigned long address) +{ + int ret; + + ret = sprint_symbol(buffer, address); + if (ret == -1) + ret = sprintf(buffer, "0x%lx", address); + + return ret; +} + +static inline int +trace_sprint_symbol_no_offset(char *buffer, unsigned long address) +{ + int ret; + + ret = sprint_symbol_no_offset(buffer, address); + if (ret == -1) + ret = sprintf(buffer, "0x%lx", address); + + return ret; +} + #endif /* _LINUX_KERNEL_TRACE_H */ diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 1e1558c99d56..3e28522a76f4 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -982,7 +982,7 @@ static void hist_trigger_stacktrace_print(struct seq_file *m, return; seq_printf(m, "%*c", 1 + spaces, ' '); - sprint_symbol(str, stacktrace_entries[i]); + trace_sprint_symbol_addr(str, stacktrace_entries[i]); seq_printf(m, "%s\n", str); } } @@ -1014,12 +1014,12 @@ hist_trigger_entry_print(struct seq_file *m, seq_printf(m, "%s: %llx", field_name, uval); } else if (key_field->flags & HIST_FIELD_FL_SYM) { uval = *(u64 *)(key + key_field->offset); - sprint_symbol_no_offset(str, uval); + trace_sprint_symbol_no_offset(str, uval); seq_printf(m, "%s: [%llx] %-45s", field_name, uval, str); } else if (key_field->flags & HIST_FIELD_FL_SYM_OFFSET) { uval = *(u64 *)(key + key_field->offset); - sprint_symbol(str, uval); + trace_sprint_symbol(str, uval); seq_printf(m, "%s: [%llx] %-55s", field_name, uval, str); } else if (key_field->flags & HIST_FIELD_FL_EXECNAME) {
Fixes behaviour modified by: commit bd6b239cdbb2 ("kallsyms: don't leak address when symbol not found") Previous patch changed behaviour of kallsyms function sprint_symbol() to return an error code instead of printing the address if a symbol was not found. Ftrace relies on the original behaviour. We should not break tracing when applying the previous patch. We can maintain the original behaviour by checking the return code on calls to sprint_symbol() and friends. Check return code and print actual address on error (i.e symbol not found). Signed-off-by: Tobin C. Harding <me@tobin.cc> --- kernel/trace/trace.h | 24 ++++++++++++++++++++++++ kernel/trace/trace_events_hist.c | 6 +++--- 2 files changed, 27 insertions(+), 3 deletions(-)