[01/20] function_graph: Convert ret_stack to a series of longs

Message ID	20240525023741.365891629@goodmis.org (mailing list archive)
State	Superseded
Headers	show 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 757BA138C; Sat, 25 May 2024 02:36:53 +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=1716604613; cv=none; b=C+8ev12RS3HBK0cvVOiQ4jTsj0/YnKSi/ScTU2iPJiDbOUQBJVL2D5zne27KOnnJR2INBYfXwz2dty+TfFJKvzB0ZZJnD0TwIQD0ZpPZ36AHo/kv8hQnPddTsyiHEZ6C1JcRloW/hQ+tPisDIzFgO5B2MLqxzCWeYzBsxXd+M50= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716604613; c=relaxed/simple; bh=gYmnuxroUnKcPJEbo40Fe17qNPPlV/8BKIflXLRQpJg=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=WZnxNdDq3h3j0zMgO/XBKCbnIlz9uPdOJmhD47G9dZcexezEmM/2sIePpUJOlrYVig0XDIYwUem32nybuSGh7mkE6CxLJL2ZcOi0BbhxoNtYLDgfgMqdF6+hbczkk7VaTGeM9blE297InNPm8mmB/VWSR2/+Sm2YTRDSmeDm90I= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id E7876C2BD11; Sat, 25 May 2024 02:36:52 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.97) (envelope-from <rostedt@goodmis.org>) id 1sAhHx-00000007DIA-26md; Fri, 24 May 2024 22:37:41 -0400 Message-ID: <20240525023741.365891629@goodmis.org> User-Agent: quilt/0.68 Date: Fri, 24 May 2024 22:36:53 -0400 From: Steven Rostedt <rostedt@goodmis.org> To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: Masami Hiramatsu <mhiramat@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Mathieu Desnoyers <mathieu.desnoyers@efficios.com>, Andrew Morton <akpm@linux-foundation.org>, Alexei Starovoitov <alexei.starovoitov@gmail.com>, Florent Revest <revest@chromium.org>, Martin KaFai Lau <martin.lau@linux.dev>, bpf <bpf@vger.kernel.org>, Sven Schnelle <svens@linux.ibm.com>, Alexei Starovoitov <ast@kernel.org>, Jiri Olsa <jolsa@kernel.org>, Arnaldo Carvalho de Melo <acme@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, Alan Maguire <alan.maguire@oracle.com>, Peter Zijlstra <peterz@infradead.org>, Thomas Gleixner <tglx@linutronix.de>, Guo Ren <guoren@kernel.org> Subject: [PATCH 01/20] function_graph: Convert ret_stack to a series of longs References: <20240525023652.903909489@goodmis.org> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: <linux-trace-kernel.vger.kernel.org> List-Subscribe: <mailto:linux-trace-kernel+subscribe@vger.kernel.org> List-Unsubscribe: <mailto:linux-trace-kernel+unsubscribe@vger.kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8
Series	[01/20] function_graph: Convert ret_stack to a series of longs \| expand [01/20] function_graph: Convert ret_stack to a series of longs [02/20] fgraph: Use BUILD_BUG_ON() to make sure we have structures divisible by long [03/20] function_graph: Add an array structure that will allow multiple callbacks [04/20] function_graph: Allow multiple users to attach to function graph [05/20] function_graph: Handle tail calls for stack unwinding [06/20] function_graph: Remove logic around ftrace_graph_entry and return [07/20] ftrace/function_graph: Pass fgraph_ops to function graph callbacks [08/20] ftrace: Allow function_graph tracer to be enabled in instances [09/20] ftrace: Allow ftrace startup flags to exist without dynamic ftrace [10/20] function_graph: Have the instances use their own ftrace_ops for filtering [11/20] function_graph: Use a simple LRU for fgraph_array index number [12/20] function_graph: Add "task variables" per task for fgraph_ops [13/20] function_graph: Move set_graph_function tests to shadow stack global var [14/20] function_graph: Move graph depth stored data to shadow stack global var [15/20] function_graph: Move graph notrace bit to shadow stack global var [16/20] function_graph: Implement fgraph_reserve_data() and fgraph_retrieve_data() [17/20] function_graph: Add selftest for passing local variables [18/20] ftrace: Add multiple fgraph storage selftest [19/20] function_graph: Use for_each_set_bit() in __ftrace_return_to_handler() [20/20] function_graph: Use bitmask to loop on fgraph entry

diff --git a/include/linux/sched.h b/include/linux/sched.h index 61591ac6eab6..352939dab3a5 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1402,7 +1402,7 @@ struct task_struct { int curr_ret_depth; /* Stack of return addresses for return function tracing: */ - struct ftrace_ret_stack *ret_stack; + unsigned long *ret_stack; /* Timestamp for last schedule: */ unsigned long long ftrace_timestamp; diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c index a130b2d898f7..c62e6db718a0 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -25,6 +25,30 @@ #define ASSIGN_OPS_HASH(opsname, val) #endif +/* + * FGRAPH_FRAME_SIZE: Size in bytes of the meta data on the shadow stack + * FGRAPH_FRAME_OFFSET: Size in long words of the meta data frame + * SHADOW_STACK_SIZE: The size in bytes of the entire shadow stack + * SHADOW_STACK_OFFSET: The size in long words of the shadow stack + * SHADOW_STACK_MAX_OFFSET: The max offset of the stack for a new frame to be added + */ +#define FGRAPH_FRAME_SIZE sizeof(struct ftrace_ret_stack) +#define FGRAPH_FRAME_OFFSET (ALIGN(FGRAPH_FRAME_SIZE, sizeof(long)) / sizeof(long)) +#define SHADOW_STACK_SIZE (PAGE_SIZE) +#define SHADOW_STACK_OFFSET \ + (ALIGN(SHADOW_STACK_SIZE, sizeof(long)) / sizeof(long)) +/* Leave on a buffer at the end */ +#define SHADOW_STACK_MAX_INDEX (SHADOW_STACK_OFFSET - FGRAPH_FRAME_OFFSET) + +/* + * RET_STACK(): Return the frame from a given @offset from task @t + * RET_STACK_INC(): Reserve one frame size on the stack. + * RET_STACK_DEC(): Remove one frame size from the stack. + */ +#define RET_STACK(t, index) ((struct ftrace_ret_stack *)(&(t)->ret_stack[index])) +#define RET_STACK_INC(c) ({ c += FGRAPH_FRAME_OFFSET; }) +#define RET_STACK_DEC(c) ({ c -= FGRAPH_FRAME_OFFSET; }) + DEFINE_STATIC_KEY_FALSE(kill_ftrace_graph); int ftrace_graph_active; @@ -69,6 +93,7 @@ static int ftrace_push_return_trace(unsigned long ret, unsigned long func, unsigned long frame_pointer, unsigned long *retp) { + struct ftrace_ret_stack *ret_stack; unsigned long long calltime; int index; @@ -85,23 +110,25 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, smp_rmb(); /* The return trace stack is full */ - if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) { + if (current->curr_ret_stack >= SHADOW_STACK_MAX_INDEX) { atomic_inc(&current->trace_overrun); return -EBUSY; } calltime = trace_clock_local(); - index = ++current->curr_ret_stack; + index = current->curr_ret_stack; + RET_STACK_INC(current->curr_ret_stack); + ret_stack = RET_STACK(current, index); barrier(); - current->ret_stack[index].ret = ret; - current->ret_stack[index].func = func; - current->ret_stack[index].calltime = calltime; + ret_stack->ret = ret; + ret_stack->func = func; + ret_stack->calltime = calltime; #ifdef HAVE_FUNCTION_GRAPH_FP_TEST - current->ret_stack[index].fp = frame_pointer; + ret_stack->fp = frame_pointer; #endif #ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR - current->ret_stack[index].retp = retp; + ret_stack->retp = retp; #endif return 0; } @@ -137,7 +164,7 @@ int function_graph_enter(unsigned long ret, unsigned long func, return 0; out_ret: - current->curr_ret_stack--; + RET_STACK_DEC(current->curr_ret_stack); out: current->curr_ret_depth--; return -EBUSY; @@ -148,11 +175,13 @@ static void ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret, unsigned long frame_pointer) { + struct ftrace_ret_stack *ret_stack; int index; index = current->curr_ret_stack; + RET_STACK_DEC(index); - if (unlikely(index < 0 || index >= FTRACE_RETFUNC_DEPTH)) { + if (unlikely(index < 0 || index > SHADOW_STACK_MAX_INDEX)) { ftrace_graph_stop(); WARN_ON(1); /* Might as well panic, otherwise we have no where to go */ @@ -160,6 +189,7 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret, return; } + ret_stack = RET_STACK(current, index); #ifdef HAVE_FUNCTION_GRAPH_FP_TEST /* * The arch may choose to record the frame pointer used @@ -175,22 +205,22 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret, * Note, -mfentry does not use frame pointers, and this test * is not needed if CC_USING_FENTRY is set. */ - if (unlikely(current->ret_stack[index].fp != frame_pointer)) { + if (unlikely(ret_stack->fp != frame_pointer)) { ftrace_graph_stop(); WARN(1, "Bad frame pointer: expected %lx, received %lx\n" " from func %ps return to %lx\n", current->ret_stack[index].fp, frame_pointer, - (void *)current->ret_stack[index].func, - current->ret_stack[index].ret); + (void *)ret_stack->func, + ret_stack->ret); *ret = (unsigned long)panic; return; } #endif - *ret = current->ret_stack[index].ret; - trace->func = current->ret_stack[index].func; - trace->calltime = current->ret_stack[index].calltime; + *ret = ret_stack->ret; + trace->func = ret_stack->func; + trace->calltime = ret_stack->calltime; trace->overrun = atomic_read(&current->trace_overrun); trace->depth = current->curr_ret_depth--; /* @@ -251,7 +281,7 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs * curr_ret_stack is after that. */ barrier(); - current->curr_ret_stack--; + RET_STACK_DEC(current->curr_ret_stack); if (unlikely(!ret)) { ftrace_graph_stop(); @@ -294,12 +324,13 @@ unsigned long ftrace_return_to_handler(unsigned long frame_pointer) struct ftrace_ret_stack * ftrace_graph_get_ret_stack(struct task_struct *task, int idx) { - idx = task->curr_ret_stack - idx; + int index = task->curr_ret_stack; - if (idx >= 0 && idx <= task->curr_ret_stack) - return &task->ret_stack[idx]; + index -= FGRAPH_FRAME_OFFSET * (idx + 1); + if (index < 0) + return NULL; - return NULL; + return RET_STACK(task, index); } /** @@ -321,18 +352,20 @@ ftrace_graph_get_ret_stack(struct task_struct *task, int idx) unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx, unsigned long ret, unsigned long *retp) { + struct ftrace_ret_stack *ret_stack; int index = task->curr_ret_stack; int i; if (ret != (unsigned long)dereference_kernel_function_descriptor(return_to_handler)) return ret; - if (index < 0) - return ret; + RET_STACK_DEC(index); - for (i = 0; i <= index; i++) - if (task->ret_stack[i].retp == retp) - return task->ret_stack[i].ret; + for (i = index; i >= 0; RET_STACK_DEC(i)) { + ret_stack = RET_STACK(task, i); + if (ret_stack->retp == retp) + return ret_stack->ret; + } return ret; } @@ -346,14 +379,15 @@ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx, return ret; task_idx = task->curr_ret_stack; + RET_STACK_DEC(task_idx); if (!task->ret_stack || task_idx < *idx) return ret; task_idx -= *idx; - (*idx)++; + RET_STACK_INC(*idx); - return task->ret_stack[task_idx].ret; + return RET_STACK(task, task_idx); } #endif /* HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */ @@ -391,7 +425,7 @@ trace_func_graph_ent_t ftrace_graph_entry = ftrace_graph_entry_stub; static trace_func_graph_ent_t __ftrace_graph_entry = ftrace_graph_entry_stub; /* Try to assign a return stack array on FTRACE_RETSTACK_ALLOC_SIZE tasks. */ -static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list) +static int alloc_retstack_tasklist(unsigned long **ret_stack_list) { int i; int ret = 0; @@ -399,10 +433,7 @@ static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list) struct task_struct *g, *t; for (i = 0; i < FTRACE_RETSTACK_ALLOC_SIZE; i++) { - ret_stack_list[i] = - kmalloc_array(FTRACE_RETFUNC_DEPTH, - sizeof(struct ftrace_ret_stack), - GFP_KERNEL); + ret_stack_list[i] = kmalloc(SHADOW_STACK_SIZE, GFP_KERNEL); if (!ret_stack_list[i]) { start = 0; end = i; @@ -420,9 +451,9 @@ static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list) if (t->ret_stack == NULL) { atomic_set(&t->trace_overrun, 0); - t->curr_ret_stack = -1; + t->curr_ret_stack = 0; t->curr_ret_depth = -1; - /* Make sure the tasks see the -1 first: */ + /* Make sure the tasks see the 0 first: */ smp_wmb(); t->ret_stack = ret_stack_list[start++]; } @@ -442,6 +473,7 @@ ftrace_graph_probe_sched_switch(void *ignore, bool preempt, struct task_struct *next, unsigned int prev_state) { + struct ftrace_ret_stack *ret_stack; unsigned long long timestamp; int index; @@ -466,8 +498,11 @@ ftrace_graph_probe_sched_switch(void *ignore, bool preempt, */ timestamp -= next->ftrace_timestamp; - for (index = next->curr_ret_stack; index >= 0; index--) - next->ret_stack[index].calltime += timestamp; + for (index = next->curr_ret_stack - FGRAPH_FRAME_OFFSET; index >= 0; ) { + ret_stack = RET_STACK(next, index); + ret_stack->calltime += timestamp; + index -= FGRAPH_FRAME_OFFSET; + } } static int ftrace_graph_entry_test(struct ftrace_graph_ent *trace) @@ -510,10 +545,10 @@ void update_function_graph_func(void) ftrace_graph_entry = __ftrace_graph_entry; } -static DEFINE_PER_CPU(struct ftrace_ret_stack *, idle_ret_stack); +static DEFINE_PER_CPU(unsigned long *, idle_ret_stack); static void -graph_init_task(struct task_struct *t, struct ftrace_ret_stack *ret_stack) +graph_init_task(struct task_struct *t, unsigned long *ret_stack) { atomic_set(&t->trace_overrun, 0); t->ftrace_timestamp = 0; @@ -528,7 +563,7 @@ graph_init_task(struct task_struct *t, struct ftrace_ret_stack *ret_stack) */ void ftrace_graph_init_idle_task(struct task_struct *t, int cpu) { - t->curr_ret_stack = -1; + t->curr_ret_stack = 0; t->curr_ret_depth = -1; /* * The idle task has no parent, it either has its own @@ -538,14 +573,11 @@ void ftrace_graph_init_idle_task(struct task_struct *t, int cpu) WARN_ON(t->ret_stack != per_cpu(idle_ret_stack, cpu)); if (ftrace_graph_active) { - struct ftrace_ret_stack *ret_stack; + unsigned long *ret_stack; ret_stack = per_cpu(idle_ret_stack, cpu); if (!ret_stack) { - ret_stack = - kmalloc_array(FTRACE_RETFUNC_DEPTH, - sizeof(struct ftrace_ret_stack), - GFP_KERNEL); + ret_stack = kmalloc(SHADOW_STACK_SIZE, GFP_KERNEL); if (!ret_stack) return; per_cpu(idle_ret_stack, cpu) = ret_stack; @@ -559,15 +591,13 @@ void ftrace_graph_init_task(struct task_struct *t) { /* Make sure we do not use the parent ret_stack */ t->ret_stack = NULL; - t->curr_ret_stack = -1; + t->curr_ret_stack = 0; t->curr_ret_depth = -1; if (ftrace_graph_active) { - struct ftrace_ret_stack *ret_stack; + unsigned long *ret_stack; - ret_stack = kmalloc_array(FTRACE_RETFUNC_DEPTH, - sizeof(struct ftrace_ret_stack), - GFP_KERNEL); + ret_stack = kmalloc(SHADOW_STACK_SIZE, GFP_KERNEL); if (!ret_stack) return; graph_init_task(t, ret_stack); @@ -576,7 +606,7 @@ void ftrace_graph_init_task(struct task_struct *t) void ftrace_graph_exit_task(struct task_struct *t) { - struct ftrace_ret_stack *ret_stack = t->ret_stack; + unsigned long *ret_stack = t->ret_stack; t->ret_stack = NULL; /* NULL must become visible to IRQs before we free it: */ @@ -588,12 +618,10 @@ void ftrace_graph_exit_task(struct task_struct *t) /* Allocate a return stack for each task */ static int start_graph_tracing(void) { - struct ftrace_ret_stack **ret_stack_list; + unsigned long **ret_stack_list; int ret, cpu; - ret_stack_list = kmalloc_array(FTRACE_RETSTACK_ALLOC_SIZE, - sizeof(struct ftrace_ret_stack *), - GFP_KERNEL); + ret_stack_list = kmalloc(SHADOW_STACK_SIZE, GFP_KERNEL); if (!ret_stack_list) return -ENOMEM;

[01/20] function_graph: Convert ret_stack to a series of longs

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