| Message ID | 20181205183303.828422192@goodmis.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | tracing: arm64: Make ftrace_replace_code() schedulable for arm64 | expand |
On Wed, 5 Dec 2018 at 19:33, Steven Rostedt <rostedt@goodmis.org> wrote: > > From: "Steven Rostedt (VMware)" <rostedt@goodmis.org> > > The function ftrace_replace_code() is the ftrace engine that does the > work to modify all the nops into the calls to the function callback in > all the functions being traced. > > The generic version which is normally called from stop machine, but an > architecture can implement a non stop machine version and still use the > generic ftrace_replace_code(). When an architecture does this, > ftrace_replace_code() may be called from a schedulable context, where > it can allow the code to be preemptible, and schedule out. > > In order to allow an architecture to make ftrace_replace_code() > schedulable, a new command flag is added called: > > FTRACE_SCHEDULABLE > > Which can be or'd to the command that is passed to > ftrace_modify_all_code() that calls ftrace_replace_code() and will have > it call cond_resched() in the loop that modifies the nops into the > calls to the ftrace trampolines. > > Link: http://lkml.kernel.org/r/20181204192903.8193-1-anders.roxell@linaro.org > > Reported-by: Anders Roxell <anders.roxell@linaro.org> > Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Tested-by: Anders Roxell <anders.roxell@linaro.org> Cheers, Anders > --- > include/linux/ftrace.h | 1 + > kernel/trace/ftrace.c | 19 ++++++++++++++++--- > 2 files changed, 17 insertions(+), 3 deletions(-) > > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h > index dd16e8218db3..c281b16baef9 100644 > --- a/include/linux/ftrace.h > +++ b/include/linux/ftrace.h > @@ -389,6 +389,7 @@ enum { > FTRACE_UPDATE_TRACE_FUNC = (1 << 2), > FTRACE_START_FUNC_RET = (1 << 3), > FTRACE_STOP_FUNC_RET = (1 << 4), > + FTRACE_SCHEDULABLE = (1 << 5), > }; > > /* > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index 77734451cb05..74fdcacba514 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -77,6 +77,11 @@ > #define ASSIGN_OPS_HASH(opsname, val) > #endif > > +enum { > + FTRACE_MODIFY_ENABLE_FL = (1 << 0), > + FTRACE_MODIFY_SCHEDULABLE_FL = (1 << 1), > +}; > + > static struct ftrace_ops ftrace_list_end __read_mostly = { > .func = ftrace_stub, > .flags = FTRACE_OPS_FL_RECURSION_SAFE | FTRACE_OPS_FL_STUB, > @@ -2415,10 +2420,12 @@ __ftrace_replace_code(struct dyn_ftrace *rec, int enable) > return -1; /* unknow ftrace bug */ > } > > -void __weak ftrace_replace_code(int enable) > +void __weak ftrace_replace_code(int mod_flags) > { > struct dyn_ftrace *rec; > struct ftrace_page *pg; > + int enable = mod_flags & FTRACE_MODIFY_ENABLE_FL; > + int schedulable = mod_flags & FTRACE_MODIFY_SCHEDULABLE_FL; > int failed; > > if (unlikely(ftrace_disabled)) > @@ -2435,6 +2442,8 @@ void __weak ftrace_replace_code(int enable) > /* Stop processing */ > return; > } > + if (schedulable) > + cond_resched(); > } while_for_each_ftrace_rec(); > } > > @@ -2548,8 +2557,12 @@ int __weak ftrace_arch_code_modify_post_process(void) > void ftrace_modify_all_code(int command) > { > int update = command & FTRACE_UPDATE_TRACE_FUNC; > + int mod_flags = 0; > int err = 0; > > + if (command & FTRACE_SCHEDULABLE) > + mod_flags = FTRACE_MODIFY_SCHEDULABLE_FL; > + > /* > * If the ftrace_caller calls a ftrace_ops func directly, > * we need to make sure that it only traces functions it > @@ -2567,9 +2580,9 @@ void ftrace_modify_all_code(int command) > } > > if (command & FTRACE_UPDATE_CALLS) > - ftrace_replace_code(1); > + ftrace_replace_code(mod_flags | FTRACE_MODIFY_ENABLE_FL); > else if (command & FTRACE_DISABLE_CALLS) > - ftrace_replace_code(0); > + ftrace_replace_code(mod_flags); > > if (update && ftrace_trace_function != ftrace_ops_list_func) { > function_trace_op = set_function_trace_op; > -- > 2.19.1 > >
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index dd16e8218db3..c281b16baef9 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -389,6 +389,7 @@ enum { FTRACE_UPDATE_TRACE_FUNC = (1 << 2), FTRACE_START_FUNC_RET = (1 << 3), FTRACE_STOP_FUNC_RET = (1 << 4), + FTRACE_SCHEDULABLE = (1 << 5), }; /* diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 77734451cb05..74fdcacba514 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -77,6 +77,11 @@ #define ASSIGN_OPS_HASH(opsname, val) #endif +enum { + FTRACE_MODIFY_ENABLE_FL = (1 << 0), + FTRACE_MODIFY_SCHEDULABLE_FL = (1 << 1), +}; + static struct ftrace_ops ftrace_list_end __read_mostly = { .func = ftrace_stub, .flags = FTRACE_OPS_FL_RECURSION_SAFE | FTRACE_OPS_FL_STUB, @@ -2415,10 +2420,12 @@ __ftrace_replace_code(struct dyn_ftrace *rec, int enable) return -1; /* unknow ftrace bug */ } -void __weak ftrace_replace_code(int enable) +void __weak ftrace_replace_code(int mod_flags) { struct dyn_ftrace *rec; struct ftrace_page *pg; + int enable = mod_flags & FTRACE_MODIFY_ENABLE_FL; + int schedulable = mod_flags & FTRACE_MODIFY_SCHEDULABLE_FL; int failed; if (unlikely(ftrace_disabled)) @@ -2435,6 +2442,8 @@ void __weak ftrace_replace_code(int enable) /* Stop processing */ return; } + if (schedulable) + cond_resched(); } while_for_each_ftrace_rec(); } @@ -2548,8 +2557,12 @@ int __weak ftrace_arch_code_modify_post_process(void) void ftrace_modify_all_code(int command) { int update = command & FTRACE_UPDATE_TRACE_FUNC; + int mod_flags = 0; int err = 0; + if (command & FTRACE_SCHEDULABLE) + mod_flags = FTRACE_MODIFY_SCHEDULABLE_FL; + /* * If the ftrace_caller calls a ftrace_ops func directly, * we need to make sure that it only traces functions it @@ -2567,9 +2580,9 @@ void ftrace_modify_all_code(int command) } if (command & FTRACE_UPDATE_CALLS) - ftrace_replace_code(1); + ftrace_replace_code(mod_flags | FTRACE_MODIFY_ENABLE_FL); else if (command & FTRACE_DISABLE_CALLS) - ftrace_replace_code(0); + ftrace_replace_code(mod_flags); if (update && ftrace_trace_function != ftrace_ops_list_func) { function_trace_op = set_function_trace_op;