From patchwork Wed Nov 8 14:25:06 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Masami Hiramatsu (Google)" X-Patchwork-Id: 13450150 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 DCB7919BCC; Wed, 8 Nov 2023 14:25:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="sgLJ/sWK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6CE58C433C8; Wed, 8 Nov 2023 14:25:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1699453512; bh=BaKMcq+s6VngWMd3ngPTESGkVeznx5ygK1pn7TSuURA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sgLJ/sWKIxy6K4+5EGl2FlDx2ep1RD/nVKPn/lNwJzJ+7IkGiInhlKntdm1DpnvVM SEMEikk9RA60Yt1yg1LZvu+LwJJYJkrvTVeEB8A6OxXcLAYJABy7dtg+mWwTW3diXv lmXiIZOVufBCqrN03cbf3IO9kk/HbRQTjHlsyxe3nGFtKdQOvX5aZeNMAEC/IWGqLz j34jmYfgD+529a+PbiI1io6FJAHM2tiFg40OEZUM9m1O7fOzKC67EbMTDerftioG/p SVcSBj/eKbWRA+sUy1YNvp++/aq8gmX8hn0P6r+VhiHVX73GoqH0RMCxo4gpb6zWMi eWRPAQGVxcERQ== 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: [RFC PATCH v2 04/31] function_graph: Convert ret_stack to a series of longs Date: Wed, 8 Nov 2023 23:25:06 +0900 Message-Id: <169945350631.55307.6150193493645509447.stgit@devnote2> X-Mailer: git-send-email 2.34.1 In-Reply-To: <169945345785.55307.5003201137843449313.stgit@devnote2> References: <169945345785.55307.5003201137843449313.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 X-Patchwork-State: RFC From: Steven Rostedt (VMware) In order to make it possible to have multiple callbacks registered with the function_graph tracer, the retstack needs to be converted from an array of ftrace_ret_stack structures to an array of longs. This will allow to store the list of callbacks on the stack for the return side of the functions. Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Masami Hiramatsu (Google) --- include/linux/sched.h | 2 - kernel/trace/fgraph.c | 124 ++++++++++++++++++++++++++++--------------------- 2 files changed, 71 insertions(+), 55 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 77f01ac385f7..3af00d726847 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1386,7 +1386,7 @@ 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 c83c005e654e..30edeb6d4aa9 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -25,6 +25,18 @@ #define ASSIGN_OPS_HASH(opsname, val) #endif +#define FGRAPH_RET_SIZE sizeof(struct ftrace_ret_stack) +#define FGRAPH_RET_INDEX (ALIGN(FGRAPH_RET_SIZE, sizeof(long)) / sizeof(long)) +#define SHADOW_STACK_SIZE (PAGE_SIZE) +#define SHADOW_STACK_INDEX \ + (ALIGN(SHADOW_STACK_SIZE, sizeof(long)) / sizeof(long)) +/* Leave on a buffer at the end */ +#define SHADOW_STACK_MAX_INDEX (SHADOW_STACK_INDEX - FGRAPH_RET_INDEX) + +#define RET_STACK(t, index) ((struct ftrace_ret_stack *)(&(t)->ret_stack[index])) +#define RET_STACK_INC(c) ({ c += FGRAPH_RET_INDEX; }) +#define RET_STACK_DEC(c) ({ c -= FGRAPH_RET_INDEX; }) + DEFINE_STATIC_KEY_FALSE(kill_ftrace_graph); int ftrace_graph_active; @@ -69,6 +81,7 @@ 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 +98,25 @@ 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(¤t->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; } @@ -148,7 +163,7 @@ 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; @@ -159,11 +174,13 @@ 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 */ @@ -171,6 +188,7 @@ 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 @@ -186,22 +204,22 @@ 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(¤t->trace_overrun); trace->depth = current->curr_ret_depth--; /* @@ -262,7 +280,7 @@ 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(); @@ -305,12 +323,13 @@ 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_RET_INDEX * (idx + 1); + if (index < 0) + return NULL; - return NULL; + return RET_STACK(task, index); } /** @@ -332,18 +351,20 @@ 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; } @@ -357,14 +378,15 @@ 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 */ @@ -402,7 +424,7 @@ 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; @@ -410,10 +432,7 @@ 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; @@ -431,9 +450,9 @@ 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++]; } @@ -453,6 +472,7 @@ 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; @@ -477,8 +497,11 @@ 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_RET_INDEX; index >= 0; ) { + ret_stack = RET_STACK(next, index); + ret_stack->calltime += timestamp; + index -= FGRAPH_RET_INDEX; + } } static int ftrace_graph_entry_test(struct ftrace_graph_ent *trace) @@ -521,10 +544,10 @@ 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; @@ -539,7 +562,7 @@ 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 @@ -549,14 +572,11 @@ 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; @@ -570,15 +590,13 @@ 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); @@ -587,7 +605,7 @@ 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: */ @@ -599,12 +617,10 @@ 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;