From patchwork Sun Feb 25 15:18:20 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Masami Hiramatsu (Google)" X-Patchwork-Id: 13570861 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C8DDF1B7FC; Sun, 25 Feb 2024 15:18:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708874305; cv=none; b=kYi+Mcgs9GZBZWBs1mgB/bJ23NKQSrWyYzzyZr8MlEjSAjs7NlCXrMjjtLkiFCDF3aSOOaKw22y0qlRFT18tLjrKBcIFr7rGCYwaFDYV3900PGxBlBudQSyWPc4WfKhleNzd/LQpOV5kklwNRysU4zhlcJ2P36bh1AJ4m0CXoUw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708874305; c=relaxed/simple; bh=/Y6Rr19lm5RDsWlFd7LZ0gC4gAR8Li0fDvhYnmOF7Kc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=KghqQCCnLZ05Z67izP3cHKNZuoQDW8YYMXWoFgor0YUkJKan886Rb1oQBgiLV22MvQl3Wr9ZCi1sVUqK6hmbtmwJwPuVzunFC6GW6jNVZ52ZVAuT93MkoUq7F65e3vIZMFqrclcGzY1pvlILE6Weu26ihcnk13IZ3gKcYWqfJ74= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hUxNb0VH; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="hUxNb0VH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9D39FC433F1; Sun, 25 Feb 2024 15:18:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1708874305; bh=/Y6Rr19lm5RDsWlFd7LZ0gC4gAR8Li0fDvhYnmOF7Kc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hUxNb0VHxSV+9kh0volmyv7RFiNE6MdL/je2VDsw+dKRhjMpT7lxykYLhTPxCz7dI bN3dZpaBKUvawtaJphPpaA7vzErdFPVTxYr6X4gggpGH2++DHwVFq8pcjSfao5ahw2 Bxsh+7QRo3FKBjDw26DZMWVqCtu064cGmOwzV2uUN8z/UYAJ5kBAQG9RGKaDdcWR9y +t87Rvv4tM5SZKHy1D2nk6w8Uq+Bg1HTRzxv8yNQAKKK/V0+KHFWDI0nv4K/hL+XUD qCuhynj+06M1AFD8PeBlIxij9F7KVbqxrFp9r5E8vDzfA8Alg6ydqyomEbPmvsoVV9 nd7zLOsPmYxZg== From: "Masami Hiramatsu (Google)" To: Alexei Starovoitov , Steven Rostedt , Florent Revest Cc: linux-trace-kernel@vger.kernel.org, LKML , Martin KaFai Lau , bpf , Sven Schnelle , Alexei Starovoitov , Jiri Olsa , Arnaldo Carvalho de Melo , Daniel Borkmann , Alan Maguire , Mark Rutland , Peter Zijlstra , Thomas Gleixner , Guo Ren Subject: [PATCH v8 18/35] function_graph: Implement fgraph_reserve_data() and fgraph_retrieve_data() Date: Mon, 26 Feb 2024 00:18:20 +0900 Message-Id: <170887430044.564249.12915713205477530976.stgit@devnote2> X-Mailer: git-send-email 2.34.1 In-Reply-To: <170887410337.564249.6360118840946697039.stgit@devnote2> References: <170887410337.564249.6360118840946697039.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Steven Rostedt (VMware) Added functions that can be called by a fgraph_ops entryfunc and retfunc to store state between the entry of the function being traced to the exit of the same function. The fgraph_ops entryfunc() may call fgraph_reserve_data() to store up to 32 words onto the task's shadow ret_stack and this then can be retrieved by fgraph_retrieve_data() called by the corresponding retfunc(). Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Masami Hiramatsu (Google) --- Changes in v8: - Avoid using DIV_ROUND_UP() in the hot path. Changes in v3: - Store fgraph_array index to the data entry. - Both function requires fgraph_array index to store/retrieve data. - Reserve correct size of the data. - Return correct data area. Changes in v2: - Retrieve the reserved size by fgraph_retrieve_data(). - Expand the maximum data size to 32 words. - Update stack index with __get_index(val) if FGRAPH_TYPE_ARRAY entry. - fix typos and make description lines shorter than 76 chars. --- include/linux/ftrace.h | 3 + kernel/trace/fgraph.c | 175 ++++++++++++++++++++++++++++++++++++++++++++++-- 2 files changed, 170 insertions(+), 8 deletions(-) diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 737f84104577..815e865f46c9 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -1075,6 +1075,9 @@ struct fgraph_ops { int idx; }; +void *fgraph_reserve_data(int idx, int size_bytes); +void *fgraph_retrieve_data(int idx, int *size_bytes); + /* * Stack of return addresses for functions * of a thread. diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c index 780976088587..66d9ce78b292 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -41,17 +41,29 @@ * bits: 10 - 11 Type of storage * 0 - reserved * 1 - bitmap of fgraph_array index + * 2 - reserved data * * For bitmap of fgraph_array index * bits: 12 - 27 The bitmap of fgraph_ops fgraph_array index * + * For reserved data: + * bits: 12 - 17 The size in words that is stored + * bits: 18 - 23 The index of fgraph_array, which shows who is stored + * * That is, at the end of function_graph_enter, if the first and forth * fgraph_ops on the fgraph_array[] (index 0 and 3) needs their retfunc called - * on the return of the function being traced, this is what will be on the - * task's shadow ret_stack: (the stack grows upward) + * on the return of the function being traced, and the forth fgraph_ops + * stored two words of data, this is what will be on the task's shadow + * ret_stack: (the stack grows upward) * * | | <- task->curr_ret_stack * +--------------------------------------------+ + * | data_type(idx:3, size:2, | + * | offset:FGRAPH_RET_INDEX+3) | ( Data with size of 2 words) + * +--------------------------------------------+ ( It is 4 words from the ret_stack) + * | STORED DATA WORD 2 | + * | STORED DATA WORD 1 | + * +------i-------------------------------------+ * | bitmap_type(bitmap:(BIT(3)|BIT(0)), | * | offset:FGRAPH_RET_INDEX) | <- the offset is from here * +--------------------------------------------+ @@ -78,14 +90,23 @@ enum { FGRAPH_TYPE_RESERVED = 0, FGRAPH_TYPE_BITMAP = 1, + FGRAPH_TYPE_DATA = 2, }; #define FGRAPH_INDEX_SIZE 16 #define FGRAPH_INDEX_MASK GENMASK(FGRAPH_INDEX_SIZE - 1, 0) #define FGRAPH_INDEX_SHIFT (FGRAPH_TYPE_SHIFT + FGRAPH_TYPE_SIZE) -/* Currently the max stack index can't be more than register callers */ -#define FGRAPH_MAX_INDEX (FGRAPH_INDEX_SIZE + FGRAPH_RET_INDEX) +#define FGRAPH_DATA_SIZE 5 +#define FGRAPH_DATA_MASK ((1 << FGRAPH_DATA_SIZE) - 1) +#define FGRAPH_DATA_SHIFT (FGRAPH_TYPE_SHIFT + FGRAPH_TYPE_SIZE) + +#define FGRAPH_DATA_INDEX_SIZE 4 +#define FGRAPH_DATA_INDEX_MASK ((1 << FGRAPH_DATA_INDEX_SIZE) - 1) +#define FGRAPH_DATA_INDEX_SHIFT (FGRAPH_DATA_SHIFT + FGRAPH_DATA_SIZE) + +#define FGRAPH_MAX_INDEX \ + ((FGRAPH_INDEX_SIZE << FGRAPH_DATA_SIZE) + FGRAPH_RET_INDEX) #define FGRAPH_ARRAY_SIZE FGRAPH_INDEX_SIZE @@ -97,6 +118,8 @@ enum { #define RET_STACK(t, index) ((struct ftrace_ret_stack *)(&(t)->ret_stack[index])) +#define FGRAPH_MAX_DATA_SIZE (sizeof(long) * (1 << FGRAPH_DATA_SIZE)) + /* * Each fgraph_ops has a reservered unsigned long at the end (top) of the * ret_stack to store task specific state. @@ -149,14 +172,39 @@ static int fgraph_lru_alloc_index(void) return idx; } +static inline int __get_index(unsigned long val) +{ + return val & FGRAPH_RET_INDEX_MASK; +} + +static inline int __get_type(unsigned long val) +{ + return (val >> FGRAPH_TYPE_SHIFT) & FGRAPH_TYPE_MASK; +} + +static inline int __get_data_index(unsigned long val) +{ + return (val >> FGRAPH_DATA_INDEX_SHIFT) & FGRAPH_DATA_INDEX_MASK; +} + +static inline int __get_data_size(unsigned long val) +{ + return (val >> FGRAPH_DATA_SHIFT) & FGRAPH_DATA_MASK; +} + +static inline unsigned long get_fgraph_entry(struct task_struct *t, int index) +{ + return t->ret_stack[index]; +} + static inline int get_ret_stack_index(struct task_struct *t, int offset) { - return t->ret_stack[offset] & FGRAPH_RET_INDEX_MASK; + return __get_index(t->ret_stack[offset]); } static inline int get_fgraph_type(struct task_struct *t, int offset) { - return (t->ret_stack[offset] >> FGRAPH_TYPE_SHIFT) & FGRAPH_TYPE_MASK; + return __get_type(t->ret_stack[offset]); } static inline unsigned long @@ -183,6 +231,22 @@ add_fgraph_index_bitmap(struct task_struct *t, int offset, unsigned long bitmap) t->ret_stack[offset] |= (bitmap << FGRAPH_INDEX_SHIFT); } +static inline void *get_fgraph_data(struct task_struct *t, int index) +{ + unsigned long val = t->ret_stack[index]; + + if (__get_type(val) != FGRAPH_TYPE_DATA) + return NULL; + index -= __get_data_size(val); + return (void *)&t->ret_stack[index]; +} + +static inline unsigned long make_fgraph_data(int idx, int size, int offset) +{ + return (idx << FGRAPH_DATA_INDEX_SHIFT) | (size << FGRAPH_DATA_SHIFT) | + (FGRAPH_TYPE_DATA << FGRAPH_TYPE_SHIFT) | offset; +} + /* ftrace_graph_entry set to this to tell some archs to run function graph */ static int entry_run(struct ftrace_graph_ent *trace, struct fgraph_ops *ops) { @@ -216,6 +280,92 @@ static void ret_stack_init_task_vars(unsigned long *ret_stack) memset(gvals, 0, sizeof(*gvals) * FGRAPH_ARRAY_SIZE); } +/** + * fgraph_reserve_data - Reserve storage on the task's ret_stack + * @idx: The index of fgraph_array + * @size_bytes: The size in bytes to reserve + * + * Reserves space of up to FGRAPH_MAX_DATA_SIZE bytes on the + * task's ret_stack shadow stack, for a given fgraph_ops during + * the entryfunc() call. If entryfunc() returns zero, the storage + * is discarded. An entryfunc() can only call this once per iteration. + * The fgraph_ops retfunc() can retrieve this stored data with + * fgraph_retrieve_data(). + * + * Returns: On success, a pointer to the data on the stack. + * Otherwise, NULL if there's not enough space left on the + * ret_stack for the data, or if fgraph_reserve_data() was called + * more than once for a single entryfunc() call. + */ +void *fgraph_reserve_data(int idx, int size_bytes) +{ + unsigned long val; + void *data; + int curr_ret_stack = current->curr_ret_stack; + int data_size; + + if (size_bytes > FGRAPH_MAX_DATA_SIZE) + return NULL; + + /* Convert to number of longs + data word */ + data_size = (size_bytes + sizeof(long) - 1) >> (sizeof(long) == 4 ? 2 : 3); + + val = get_fgraph_entry(current, curr_ret_stack - 1); + data = ¤t->ret_stack[curr_ret_stack]; + + curr_ret_stack += data_size + 1; + if (unlikely(curr_ret_stack >= SHADOW_STACK_MAX_INDEX)) + return NULL; + + val = make_fgraph_data(idx, data_size, __get_index(val) + data_size + 1); + + /* Set the last word to be reserved */ + current->ret_stack[curr_ret_stack - 1] = val; + + /* Make sure interrupts see this */ + barrier(); + current->curr_ret_stack = curr_ret_stack; + /* Again sync with interrupts, and reset reserve */ + current->ret_stack[curr_ret_stack - 1] = val; + + return data; +} + +/** + * fgraph_retrieve_data - Retrieve stored data from fgraph_reserve_data() + * @idx: the index of fgraph_array (fgraph_ops::idx) + * @size_bytes: pointer to retrieved data size. + * + * This is to be called by a fgraph_ops retfunc(), to retrieve data that + * was stored by the fgraph_ops entryfunc() on the function entry. + * That is, this will retrieve the data that was reserved on the + * entry of the function that corresponds to the exit of the function + * that the fgraph_ops retfunc() is called on. + * + * Returns: The stored data from fgraph_reserve_data() called by the + * matching entryfunc() for the retfunc() this is called from. + * Or NULL if there was nothing stored. + */ +void *fgraph_retrieve_data(int idx, int *size_bytes) +{ + int index = current->curr_ret_stack - 1; + unsigned long val; + + val = get_fgraph_entry(current, index); + while (__get_type(val) == FGRAPH_TYPE_DATA) { + if (__get_data_index(val) == idx) + goto found; + index -= __get_data_size(val) + 1; + val = get_fgraph_entry(current, index); + } + return NULL; +found: + if (size_bytes) + *size_bytes = __get_data_size(val) * + sizeof(long); + return get_fgraph_data(current, index); +} + /** * fgraph_get_task_var - retrieve a task specific state variable * @gops: The ftrace_ops that owns the task specific variable @@ -453,13 +603,18 @@ int function_graph_enter(unsigned long ret, unsigned long func, for (i = 0; i < FGRAPH_ARRAY_SIZE; i++) { struct fgraph_ops *gops = fgraph_array[i]; + int save_curr_ret_stack; if (gops == &fgraph_stub) continue; + save_curr_ret_stack = current->curr_ret_stack; if (ftrace_ops_test(&gops->ops, func, NULL) && gops->entryfunc(&trace, gops)) bitmap |= BIT(i); + else + /* Clear out any saved storage */ + current->curr_ret_stack = save_curr_ret_stack; } if (!bitmap) @@ -485,6 +640,7 @@ int function_graph_enter_ops(unsigned long ret, unsigned long func, struct fgraph_ops *gops) { struct ftrace_graph_ent trace; + int save_curr_ret_stack; int index; int type; @@ -504,13 +660,15 @@ int function_graph_enter_ops(unsigned long ret, unsigned long func, trace.func = func; trace.depth = current->curr_ret_depth; + save_curr_ret_stack = current->curr_ret_stack; if (gops->entryfunc(&trace, gops)) { if (type == FGRAPH_TYPE_RESERVED) set_fgraph_index_bitmap(current, index, BIT(gops->idx)); else add_fgraph_index_bitmap(current, index, BIT(gops->idx)); return 0; - } + } else + current->curr_ret_stack = save_curr_ret_stack; if (type == FGRAPH_TYPE_RESERVED) { current->curr_ret_stack -= FGRAPH_RET_INDEX + 1; @@ -655,7 +813,8 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs * curr_ret_stack is after that. */ barrier(); - current->curr_ret_stack -= FGRAPH_RET_INDEX + 1; + current->curr_ret_stack = index - FGRAPH_RET_INDEX; + current->curr_ret_depth--; return ret; }