This is a continuation of the function graph multi user code. I wrote a proof of concept back in 2019 of this code[1] and Masami started cleaning it up. I started from Masami's work v10 that can be found here: https://lore.kernel.org/linux-trace-kernel/171509088006.162236.7227326999861366050.stgit@devnote2/ This is *only* the code that allows multiple users of function graph tracing. This is not the fprobe work that Masami is working to add on top of it. As Masami took my proof of concept, there was still several things I disliked about that code. Instead of having Masami clean it up even more, I decided to take over on just my code and change it up a bit. Changes since v2: https://lore.kernel.org/linux-trace-kernel/20240602033744.563858532@xxxxxxxxxxx - Added comments describing which hashes the append and intersect functions were used for. - Replaced checks of (NULL or EMPTY_HASH) with ftrace_hash_empty() helper function. - Added check at the end of intersect_hash() to convert the hash to EMPTY hash if it doesn't have any functions. - Renamed compare_ops() to ops_equal() and return boolean (inversed return value). - Broke out __ftrace_hash_move_and_update_ops() to use in both ftrace_hash_move_and_update_ops() and ftrace_hash_move_and_update_subops(). Diff between last version at end of this email. Masami Hiramatsu (Google) (3): function_graph: Handle tail calls for stack unwinding function_graph: Use a simple LRU for fgraph_array index number ftrace: Add multiple fgraph storage selftest Steven Rostedt (Google) (9): ftrace: Add subops logic to allow one ops to manage many ftrace: Allow subops filtering to be modified function_graph: Add pid tracing back to function graph tracer function_graph: Use for_each_set_bit() in __ftrace_return_to_handler() function_graph: Use bitmask to loop on fgraph entry function_graph: Use static_call and branch to optimize entry function function_graph: Use static_call and branch to optimize return function selftests/ftrace: Add function_graph tracer to func-filter-pid test selftests/ftrace: Add fgraph-multi.tc test Steven Rostedt (VMware) (15): function_graph: Convert ret_stack to a series of longs fgraph: Use BUILD_BUG_ON() to make sure we have structures divisible by long function_graph: Add an array structure that will allow multiple callbacks function_graph: Allow multiple users to attach to function graph function_graph: Remove logic around ftrace_graph_entry and return ftrace/function_graph: Pass fgraph_ops to function graph callbacks ftrace: Allow function_graph tracer to be enabled in instances ftrace: Allow ftrace startup flags to exist without dynamic ftrace function_graph: Have the instances use their own ftrace_ops for filtering function_graph: Add "task variables" per task for fgraph_ops function_graph: Move set_graph_function tests to shadow stack global var function_graph: Move graph depth stored data to shadow stack global var function_graph: Move graph notrace bit to shadow stack global var function_graph: Implement fgraph_reserve_data() and fgraph_retrieve_data() function_graph: Add selftest for passing local variables ---- include/linux/ftrace.h | 43 +- include/linux/sched.h | 2 +- include/linux/trace_recursion.h | 39 - kernel/trace/fgraph.c | 1044 ++++++++++++++++---- kernel/trace/ftrace.c | 522 +++++++++- kernel/trace/ftrace_internal.h | 5 +- kernel/trace/trace.h | 94 +- kernel/trace/trace_functions.c | 8 + kernel/trace/trace_functions_graph.c | 96 +- kernel/trace/trace_irqsoff.c | 10 +- kernel/trace/trace_sched_wakeup.c | 10 +- kernel/trace/trace_selftest.c | 259 ++++- .../selftests/ftrace/test.d/ftrace/fgraph-multi.tc | 103 ++ .../ftrace/test.d/ftrace/func-filter-pid.tc | 27 +- 14 files changed, 1945 insertions(+), 317 deletions(-) create mode 100644 tools/testing/selftests/ftrace/test.d/ftrace/fgraph-multi.tc diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 41fabc6d30e4..da7e6abf48b4 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -3170,7 +3170,7 @@ int ftrace_shutdown(struct ftrace_ops *ops, int command) /* Simply make a copy of @src and return it */ static struct ftrace_hash *copy_hash(struct ftrace_hash *src) { - if (!src || src == EMPTY_HASH) + if (ftrace_hash_empty(src)) return EMPTY_HASH; return alloc_and_copy_ftrace_hash(src->size_bits, src); @@ -3187,6 +3187,9 @@ static struct ftrace_hash *copy_hash(struct ftrace_hash *src) * * Otherwise, go through all of @new_hash and add anything that @hash * doesn't already have, to @hash. + * + * The filter_hash updates uses just the append_hash() function + * and the notrace_hash does not. */ static int append_hash(struct ftrace_hash **hash, struct ftrace_hash *new_hash) { @@ -3195,11 +3198,11 @@ static int append_hash(struct ftrace_hash **hash, struct ftrace_hash *new_hash) int i; /* An empty hash does everything */ - if (!*hash || *hash == EMPTY_HASH) + if (ftrace_hash_empty(*hash)) return 0; /* If new_hash has everything make hash have everything */ - if (!new_hash || new_hash == EMPTY_HASH) { + if (ftrace_hash_empty(new_hash)) { free_ftrace_hash(*hash); *hash = EMPTY_HASH; return 0; @@ -3217,7 +3220,12 @@ static int append_hash(struct ftrace_hash **hash, struct ftrace_hash *new_hash) return 0; } -/* Add to @hash only those that are in both @new_hash1 and @new_hash2 */ +/* + * Add to @hash only those that are in both @new_hash1 and @new_hash2 + * + * The notrace_hash updates uses just the intersect_hash() function + * and the filter_hash does not. + */ static int intersect_hash(struct ftrace_hash **hash, struct ftrace_hash *new_hash1, struct ftrace_hash *new_hash2) { @@ -3229,8 +3237,7 @@ static int intersect_hash(struct ftrace_hash **hash, struct ftrace_hash *new_has * If new_hash1 or new_hash2 is the EMPTY_HASH then make the hash * empty as well as empty for notrace means none are notraced. */ - if (!new_hash1 || new_hash1 == EMPTY_HASH || - !new_hash2 || new_hash2 == EMPTY_HASH) { + if (ftrace_hash_empty(new_hash1) || ftrace_hash_empty(new_hash2)) { free_ftrace_hash(*hash); *hash = EMPTY_HASH; return 0; @@ -3245,6 +3252,11 @@ static int intersect_hash(struct ftrace_hash **hash, struct ftrace_hash *new_has return -ENOMEM; } } + /* If nothing intersects, make it the empty set */ + if (ftrace_hash_empty(*hash)) { + free_ftrace_hash(*hash); + *hash = EMPTY_HASH; + } return 0; } @@ -3266,7 +3278,7 @@ static struct ftrace_hash *append_hashes(struct ftrace_ops *ops) return NULL; } /* Nothing more to do if new_hash is empty */ - if (new_hash == EMPTY_HASH) + if (ftrace_hash_empty(new_hash)) break; } return new_hash; @@ -3300,59 +3312,76 @@ static struct ftrace_hash *intersect_hashes(struct ftrace_ops *ops) return NULL; } /* Nothing more to do if new_hash is empty */ - if (new_hash == EMPTY_HASH) + if (ftrace_hash_empty(new_hash)) break; } return new_hash; } -/* Returns 0 on equal or non-zero on non-equal */ -static int compare_ops(struct ftrace_hash *A, struct ftrace_hash *B) +static bool ops_equal(struct ftrace_hash *A, struct ftrace_hash *B) { struct ftrace_func_entry *entry; int size; int i; - if (!A || A == EMPTY_HASH) - return !(!B || B == EMPTY_HASH); + if (ftrace_hash_empty(A)) + return ftrace_hash_empty(B); - if (!B || B == EMPTY_HASH) - return !(!A || A == EMPTY_HASH); + if (ftrace_hash_empty(B)) + return ftrace_hash_empty(A); if (A->count != B->count) - return 1; + return false; size = 1 << A->size_bits; for (i = 0; i < size; i++) { hlist_for_each_entry(entry, &A->buckets[i], hlist) { if (!__ftrace_lookup_ip(B, entry->ip)) - return 1; + return false; } } - return 0; + return true; } -static int ftrace_hash_move_and_update_ops(struct ftrace_ops *ops, - struct ftrace_hash **orig_hash, - struct ftrace_hash *hash, - int enable); +static void ftrace_ops_update_code(struct ftrace_ops *ops, + struct ftrace_ops_hash *old_hash); + +static int __ftrace_hash_move_and_update_ops(struct ftrace_ops *ops, + struct ftrace_hash **orig_hash, + struct ftrace_hash *hash, + int enable) +{ + struct ftrace_ops_hash old_hash_ops; + struct ftrace_hash *old_hash; + int ret; + + old_hash = *orig_hash; + old_hash_ops.filter_hash = ops->func_hash->filter_hash; + old_hash_ops.notrace_hash = ops->func_hash->notrace_hash; + ret = ftrace_hash_move(ops, enable, orig_hash, hash); + if (!ret) { + ftrace_ops_update_code(ops, &old_hash_ops); + free_ftrace_hash_rcu(old_hash); + } + return ret; +} static int ftrace_update_ops(struct ftrace_ops *ops, struct ftrace_hash *filter_hash, struct ftrace_hash *notrace_hash) { int ret; - if (compare_ops(filter_hash, ops->func_hash->filter_hash)) { - ret = ftrace_hash_move_and_update_ops(ops, &ops->func_hash->filter_hash, - filter_hash, 1); + if (!ops_equal(filter_hash, ops->func_hash->filter_hash)) { + ret = __ftrace_hash_move_and_update_ops(ops, &ops->func_hash->filter_hash, + filter_hash, 1); if (ret < 0) return ret; } - if (compare_ops(notrace_hash, ops->func_hash->notrace_hash)) { - ret = ftrace_hash_move_and_update_ops(ops, &ops->func_hash->notrace_hash, - notrace_hash, 0); + if (!ops_equal(notrace_hash, ops->func_hash->notrace_hash)) { + ret = __ftrace_hash_move_and_update_ops(ops, &ops->func_hash->notrace_hash, + notrace_hash, 0); if (ret < 0) return ret; } @@ -3438,8 +3467,8 @@ int ftrace_startup_subops(struct ftrace_ops *ops, struct ftrace_ops *subops, int * o If either notrace_hash is empty then the final stays empty * o Otherwise, the final is an intersection between the hashes */ - if (ops->func_hash->filter_hash == EMPTY_HASH || - subops->func_hash->filter_hash == EMPTY_HASH) { + if (ftrace_hash_empty(ops->func_hash->filter_hash) || + ftrace_hash_empty(subops->func_hash->filter_hash)) { filter_hash = EMPTY_HASH; } else { size_bits = max(ops->func_hash->filter_hash->size_bits, @@ -3454,8 +3483,8 @@ int ftrace_startup_subops(struct ftrace_ops *ops, struct ftrace_ops *subops, int } } - if (ops->func_hash->notrace_hash == EMPTY_HASH || - subops->func_hash->notrace_hash == EMPTY_HASH) { + if (ftrace_hash_empty(ops->func_hash->notrace_hash) || + ftrace_hash_empty(subops->func_hash->notrace_hash)) { notrace_hash = EMPTY_HASH; } else { size_bits = max(ops->func_hash->filter_hash->size_bits, @@ -3591,7 +3620,7 @@ static int ftrace_hash_move_and_update_subops(struct ftrace_ops *subops, } /* Move the hash over to the new hash */ - ret = ftrace_hash_move_and_update_ops(ops, orig_hash, new_hash, enable); + ret = __ftrace_hash_move_and_update_ops(ops, orig_hash, new_hash, enable); free_ftrace_hash(new_hash); @@ -4822,11 +4851,6 @@ static int ftrace_hash_move_and_update_ops(struct ftrace_ops *ops, struct ftrace_hash *hash, int enable) { - struct ftrace_ops_hash old_hash_ops; - struct ftrace_hash *old_hash; - struct ftrace_ops *op; - int ret; - if (ops->flags & FTRACE_OPS_FL_SUBOP) return ftrace_hash_move_and_update_subops(ops, orig_hash, hash, enable); @@ -4838,6 +4862,8 @@ static int ftrace_hash_move_and_update_ops(struct ftrace_ops *ops, * it will not affect subops that share it. */ if (!(ops->flags & FTRACE_OPS_FL_ENABLED)) { + struct ftrace_ops *op; + /* Check if any other manager subops maps to this hash */ do_for_each_ftrace_op(op, ftrace_ops_list) { struct ftrace_ops *subops; @@ -4851,15 +4877,7 @@ static int ftrace_hash_move_and_update_ops(struct ftrace_ops *ops, } while_for_each_ftrace_op(op); } - old_hash = *orig_hash; - old_hash_ops.filter_hash = ops->func_hash->filter_hash; - old_hash_ops.notrace_hash = ops->func_hash->notrace_hash; - ret = ftrace_hash_move(ops, enable, orig_hash, hash); - if (!ret) { - ftrace_ops_update_code(ops, &old_hash_ops); - free_ftrace_hash_rcu(old_hash); - } - return ret; + return __ftrace_hash_move_and_update_ops(ops, orig_hash, hash, enable); } static bool module_exists(const char *module)
