diff options
| -rw-r--r-- | include/linux/ftrace.h | 6 | ||||
| -rw-r--r-- | kernel/trace/ftrace.c | 161 |
2 files changed, 110 insertions, 57 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 4736a826baf5..660e7c698f3b 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -357,6 +357,7 @@ bool is_ftrace_trampoline(unsigned long addr); * REGS - the record wants the function to save regs * REGS_EN - the function is set up to save regs. * IPMODIFY - the record allows for the IP address to be changed. + * DISABLED - the record is not ready to be touched yet * * When a new ftrace_ops is registered and wants a function to save * pt_regs, the rec->flag REGS is set. When the function has been @@ -371,10 +372,11 @@ enum { FTRACE_FL_TRAMP = (1UL << 28), FTRACE_FL_TRAMP_EN = (1UL << 27), FTRACE_FL_IPMODIFY = (1UL << 26), + FTRACE_FL_DISABLED = (1UL << 25), }; -#define FTRACE_REF_MAX_SHIFT 26 -#define FTRACE_FL_BITS 6 +#define FTRACE_REF_MAX_SHIFT 25 +#define FTRACE_FL_BITS 7 #define FTRACE_FL_MASKED_BITS ((1UL << FTRACE_FL_BITS) - 1) #define FTRACE_FL_MASK (FTRACE_FL_MASKED_BITS << FTRACE_REF_MAX_SHIFT) #define FTRACE_REF_MAX ((1UL << FTRACE_REF_MAX_SHIFT) - 1) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 0f7ee341f89f..23683b06b18c 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1658,6 +1658,9 @@ static void __ftrace_hash_rec_update(struct ftrace_ops *ops, int in_hash = 0; int match = 0; + if (rec->flags & FTRACE_FL_DISABLED) + continue; + if (all) { /* * Only the filter_hash affects all records. @@ -2023,6 +2026,9 @@ static int ftrace_check_record(struct dyn_ftrace *rec, int enable, int update) ftrace_bug_type = FTRACE_BUG_UNKNOWN; + if (rec->flags & FTRACE_FL_DISABLED) + return FTRACE_UPDATE_IGNORE; + /* * If we are updating calls: * @@ -2833,9 +2839,9 @@ ops_references_rec(struct ftrace_ops *ops, struct dyn_ftrace *rec) if (!(ops->flags & FTRACE_OPS_FL_ENABLED)) return 0; - /* If ops traces all mods, we already accounted for it */ + /* If ops traces all then it includes this function */ if (ops_traces_mod(ops)) - return 0; + return 1; /* The function must be in the filter */ if (!ftrace_hash_empty(ops->func_hash->filter_hash) && @@ -2849,64 +2855,41 @@ ops_references_rec(struct ftrace_ops *ops, struct dyn_ftrace *rec) return 1; } -static int referenced_filters(struct dyn_ftrace *rec) -{ - struct ftrace_ops *ops; - int cnt = 0; - - for (ops = ftrace_ops_list; ops != &ftrace_list_end; ops = ops->next) { - if (ops_references_rec(ops, rec)) - cnt++; - } - - return cnt; -} - static int ftrace_update_code(struct module *mod, struct ftrace_page *new_pgs) { struct ftrace_page *pg; struct dyn_ftrace *p; cycle_t start, stop; unsigned long update_cnt = 0; - unsigned long ref = 0; - bool test = false; + unsigned long rec_flags = 0; int i; + start = ftrace_now(raw_smp_processor_id()); + /* - * When adding a module, we need to check if tracers are - * currently enabled and if they are set to trace all functions. - * If they are, we need to enable the module functions as well - * as update the reference counts for those function records. + * When a module is loaded, this function is called to convert + * the calls to mcount in its text to nops, and also to create + * an entry in the ftrace data. Now, if ftrace is activated + * after this call, but before the module sets its text to + * read-only, the modification of enabling ftrace can fail if + * the read-only is done while ftrace is converting the calls. + * To prevent this, the module's records are set as disabled + * and will be enabled after the call to set the module's text + * to read-only. */ - if (mod) { - struct ftrace_ops *ops; - - for (ops = ftrace_ops_list; - ops != &ftrace_list_end; ops = ops->next) { - if (ops->flags & FTRACE_OPS_FL_ENABLED) { - if (ops_traces_mod(ops)) - ref++; - else - test = true; - } - } - } - - start = ftrace_now(raw_smp_processor_id()); + if (mod) + rec_flags |= FTRACE_FL_DISABLED; for (pg = new_pgs; pg; pg = pg->next) { for (i = 0; i < pg->index; i++) { - int cnt = ref; /* If something went wrong, bail without enabling anything */ if (unlikely(ftrace_disabled)) return -1; p = &pg->records[i]; - if (test) - cnt += referenced_filters(p); - p->flags = cnt; + p->flags = rec_flags; /* * Do the initial record conversion from mcount jump @@ -2916,21 +2899,6 @@ static int ftrace_update_code(struct module *mod, struct ftrace_page *new_pgs) break; update_cnt++; - - /* - * If the tracing is enabled, go ahead and enable the record. - * - * The reason not to enable the record immediatelly is the - * inherent check of ftrace_make_nop/ftrace_make_call for - * correct previous instructions. Making first the NOP - * conversion puts the module to the correct state, thus - * passing the ftrace_make_call check. - */ - if (ftrace_start_up && cnt) { - int failed = __ftrace_replace_code(p, 1); - if (failed) - ftrace_bug(failed, p); - } } } @@ -4938,6 +4906,19 @@ static int ftrace_process_locs(struct module *mod, #define next_to_ftrace_page(p) container_of(p, struct ftrace_page, next) +static int referenced_filters(struct dyn_ftrace *rec) +{ + struct ftrace_ops *ops; + int cnt = 0; + + for (ops = ftrace_ops_list; ops != &ftrace_list_end; ops = ops->next) { + if (ops_references_rec(ops, rec)) + cnt++; + } + + return cnt; +} + void ftrace_release_mod(struct module *mod) { struct dyn_ftrace *rec; @@ -4980,6 +4961,75 @@ void ftrace_release_mod(struct module *mod) mutex_unlock(&ftrace_lock); } +static void ftrace_module_enable(struct module *mod) +{ + struct dyn_ftrace *rec; + struct ftrace_page *pg; + + mutex_lock(&ftrace_lock); + + if (ftrace_disabled) + goto out_unlock; + + /* + * If the tracing is enabled, go ahead and enable the record. + * + * The reason not to enable the record immediatelly is the + * inherent check of ftrace_make_nop/ftrace_make_call for + * correct previous instructions. Making first the NOP + * conversion puts the module to the correct state, thus + * passing the ftrace_make_call check. + * + * We also delay this to after the module code already set the + * text to read-only, as we now need to set it back to read-write + * so that we can modify the text. + */ + if (ftrace_start_up) + ftrace_arch_code_modify_prepare(); + + do_for_each_ftrace_rec(pg, rec) { + int cnt; + /* + * do_for_each_ftrace_rec() is a double loop. + * module text shares the pg. If a record is + * not part of this module, then skip this pg, + * which the "break" will do. + */ + if (!within_module_core(rec->ip, mod)) + break; + + cnt = 0; + + /* + * When adding a module, we need to check if tracers are + * currently enabled and if they are, and can trace this record, + * we need to enable the module functions as well as update the + * reference counts for those function records. + */ + if (ftrace_start_up) + cnt += referenced_filters(rec); + + /* This clears FTRACE_FL_DISABLED */ + rec->flags = cnt; + + if (ftrace_start_up && cnt) { + int failed = __ftrace_replace_code(rec, 1); + if (failed) { + ftrace_bug(failed, rec); + goto out_loop; + } + } + + } while_for_each_ftrace_rec(); + + out_loop: + if (ftrace_start_up) + ftrace_arch_code_modify_post_process(); + + out_unlock: + mutex_unlock(&ftrace_lock); +} + void ftrace_module_init(struct module *mod) { if (ftrace_disabled || !mod->num_ftrace_callsites) @@ -4987,6 +5037,7 @@ void ftrace_module_init(struct module *mod) ftrace_process_locs(mod, mod->ftrace_callsites, mod->ftrace_callsites + mod->num_ftrace_callsites); + ftrace_module_enable(mod); } static int ftrace_module_notify_exit(struct notifier_block *self, |