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[2604:1380:45d1:ec00::1]) by mx.google.com with ESMTPS id z1-20020ac87f81000000b00427ea0d926dsi2257324qtj.273.2024.01.05.09.09.31 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 05 Jan 2024 09:09:31 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel+bounces-18096-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel+bounces-18096-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) smtp.mailfrom="linux-kernel+bounces-18096-linux.lists.archive=gmail.com@vger.kernel.org"; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=arm.com Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ny.mirrors.kernel.org (Postfix) with ESMTPS id 69F1C1C2347A for ; Fri, 5 Jan 2024 17:09:31 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 998B732189; Fri, 5 Jan 2024 17:09:22 +0000 (UTC) X-Original-To: linux-kernel@vger.kernel.org Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id B051B31A61; Fri, 5 Jan 2024 17:09:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 7DAD0C15; Fri, 5 Jan 2024 09:10:05 -0800 (PST) Received: from FVFF77S0Q05N (unknown [10.57.85.228]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5E9413F64C; Fri, 5 Jan 2024 09:09:16 -0800 (PST) Date: Fri, 5 Jan 2024 17:09:10 +0000 From: Mark Rutland To: "Masami Hiramatsu (Google)" Cc: Alexei Starovoitov , Steven Rostedt , Florent Revest , 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 , Peter Zijlstra , Thomas Gleixner , Guo Ren Subject: Re: [PATCH v5 11/34] function_graph: Have the instances use their own ftrace_ops for filtering Message-ID: References: <170290509018.220107.1347127510564358608.stgit@devnote2> <170290522555.220107.1435543481968270637.stgit@devnote2> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <170290522555.220107.1435543481968270637.stgit@devnote2> On Mon, Dec 18, 2023 at 10:13:46PM +0900, Masami Hiramatsu (Google) wrote: > From: Steven Rostedt (VMware) > > Allow for instances to have their own ftrace_ops part of the fgraph_ops > that makes the funtion_graph tracer filter on the set_ftrace_filter file > of the instance and not the top instance. > > This also change how the function_graph handles multiple instances on the > shadow stack. Previously we use ARRAY type entries to record which one > is enabled, and this makes it a bitmap of the fgraph_array's indexes. > Previous function_graph_enter() expects calling back from > prepare_ftrace_return() function which is called back only once if it is > enabled. But this introduces different ftrace_ops for each fgraph > instance and those are called from ftrace_graph_func() one by one. Thus > we can not loop on the fgraph_array(), and need to reuse the ret_stack > pushed by the previous instance. Finding the ret_stack is easy because > we can check the ret_stack->func. But that is not enough for the self- > recursive tail-call case. Thus fgraph uses the bitmap entry to find it > is already set (this means that entry is for previous tail call). > > Signed-off-by: Steven Rostedt (VMware) > Signed-off-by: Masami Hiramatsu (Google) As a heads-up, while testing the topic/fprobe-on-fgraph branch on arm64, I get a warning which bisets down to this commit: | Testing tracer function_graph: | ------------[ cut here ]------------ | WARNING: CPU: 2 PID: 0 at arch/arm64/kernel/stacktrace.c:84 arch_stack_walk+0x3c0/0x3d8 | Modules linked in: | CPU: 2 PID: 0 Comm: swapper/2 Not tainted 6.7.0-rc2-00026-gea1e68a341c2 #12 | Hardware name: linux,dummy-virt (DT) | pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--) | pc : arch_stack_walk+0x3c0/0x3d8 | lr : arch_stack_walk+0x260/0x3d8 | sp : ffff80008318be00 | x29: ffff80008318be00 x28: ffff000003c0ae80 x27: 0000000000000000 | x26: 0000000000000000 x25: ffff000003c0ae80 x24: 0000000000000000 | x23: ffff8000800234c8 x22: ffff80008002dc30 x21: ffff800080035d10 | x20: ffff80008318bee8 x19: ffff800080023460 x18: ffff800083453c68 | x17: 0000000000000000 x16: ffff800083188000 x15: 000000008ccc5058 | x14: 0000000000000004 x13: ffff800082b8c4f0 x12: 0000000000000000 | x11: ffff800081fba9b0 x10: ffff80008318bff0 x9 : ffff800080010798 | x8 : ffff80008002dc30 x7 : ffff000003c0ae80 x6 : 00000000ffffffff | x5 : 0000000000000000 x4 : ffff8000832a3c18 x3 : ffff80008318bff0 | x2 : ffff80008002dc30 x1 : ffff80008002dc30 x0 : ffff80008002dc30 | Call trace: | arch_stack_walk+0x3c0/0x3d8 | return_address+0x40/0x80 | trace_hardirqs_on+0x8c/0x198 | __do_softirq+0xe8/0x440 | ---[ end trace 0000000000000000 ]--- That's a warning in arm64's unwind_recover_return_address() function, which fires when ftrace_graph_ret_addr() finds return_to_handler: if (state->task->ret_stack && (state->pc == (unsigned long)return_to_handler)) { unsigned long orig_pc; orig_pc = ftrace_graph_ret_addr(state->task, NULL, state->pc, (void *)state->fp); if (WARN_ON_ONCE(state->pc == orig_pc)) return -EINVAL; state->pc = orig_pc; } The rationale there is that since tail calls are (currently) disabled on arm64, the only reason for ftrace_graph_ret_addr() to return return_to_handler is when it fails to find the original return address. Does this change make it legitimate for ftrace_graph_ret_addr() to return return_to_handler in other cases, or is that a bug? Either way, we'll need *some* way to recover the original return addresss... Mark. > --- > Changes in v4: > - Simplify get_ret_stack() sanity check and use WARN_ON_ONCE() for > obviously wrong value. > - Do not check ret == return_to_handler but always read the previous > ret_stack in ftrace_push_return_trace() to check it is reusable. > - Set the bit 0 of the bitmap entry always in function_graph_enter() > because it uses bit 0 to check re-usability. > - Fix to ensure the ret_stack entry is bitmap type when checking the > bitmap. > Changes in v3: > - Pass current fgraph_ops to the new entry handler > (function_graph_enter_ops) if fgraph use ftrace. > - Add fgraph_ops::idx in this patch. > - Replace the array type with the bitmap type so that it can record > which fgraph is called. > - Fix some helper function to use passed task_struct instead of current. > - Reduce the ret-index size to 1024 words. > - Make the ret-index directly points the ret_stack. > - Fix ftrace_graph_ret_addr() to handle tail-call case correctly. > Changes in v2: > - Use ftrace_graph_func and FTRACE_OPS_GRAPH_STUB instead of > ftrace_stub and FTRACE_OPS_FL_STUB for new ftrace based fgraph. > --- > arch/arm64/kernel/ftrace.c | 19 ++ > arch/x86/kernel/ftrace.c | 19 ++ > include/linux/ftrace.h | 7 + > kernel/trace/fgraph.c | 369 ++++++++++++++++++++-------------- > kernel/trace/ftrace.c | 6 - > kernel/trace/trace.h | 16 + > kernel/trace/trace_functions.c | 2 > kernel/trace/trace_functions_graph.c | 8 + > 8 files changed, 277 insertions(+), 169 deletions(-) > > diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c > index a650f5e11fc5..205937e04ece 100644 > --- a/arch/arm64/kernel/ftrace.c > +++ b/arch/arm64/kernel/ftrace.c > @@ -481,7 +481,24 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent, > void ftrace_graph_func(unsigned long ip, unsigned long parent_ip, > struct ftrace_ops *op, struct ftrace_regs *fregs) > { > - prepare_ftrace_return(ip, &fregs->lr, fregs->fp); > + unsigned long *parent = &fregs->lr; > + struct fgraph_ops *gops = container_of(op, struct fgraph_ops, ops); > + int bit; > + > + if (unlikely(ftrace_graph_is_dead())) > + return; > + > + if (unlikely(atomic_read(¤t->tracing_graph_pause))) > + return; > + > + bit = ftrace_test_recursion_trylock(ip, *parent); > + if (bit < 0) > + return; > + > + if (!function_graph_enter_ops(*parent, ip, fregs->fp, parent, gops)) > + *parent = (unsigned long)&return_to_handler; > + > + ftrace_test_recursion_unlock(bit); > } > #else > /* > diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c > index 12df54ff0e81..845e29b4254f 100644 > --- a/arch/x86/kernel/ftrace.c > +++ b/arch/x86/kernel/ftrace.c > @@ -657,9 +657,24 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip, > struct ftrace_ops *op, struct ftrace_regs *fregs) > { > struct pt_regs *regs = &fregs->regs; > - unsigned long *stack = (unsigned long *)kernel_stack_pointer(regs); > + unsigned long *parent = (unsigned long *)kernel_stack_pointer(regs); > + struct fgraph_ops *gops = container_of(op, struct fgraph_ops, ops); > + int bit; > + > + if (unlikely(ftrace_graph_is_dead())) > + return; > + > + if (unlikely(atomic_read(¤t->tracing_graph_pause))) > + return; > > - prepare_ftrace_return(ip, (unsigned long *)stack, 0); > + bit = ftrace_test_recursion_trylock(ip, *parent); > + if (bit < 0) > + return; > + > + if (!function_graph_enter_ops(*parent, ip, 0, parent, gops)) > + *parent = (unsigned long)&return_to_handler; > + > + ftrace_test_recursion_unlock(bit); > } > #endif > > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h > index 7b08169aa51d..c431a33fe789 100644 > --- a/include/linux/ftrace.h > +++ b/include/linux/ftrace.h > @@ -1070,7 +1070,9 @@ extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace, struct fgraph > struct fgraph_ops { > trace_func_graph_ent_t entryfunc; > trace_func_graph_ret_t retfunc; > + struct ftrace_ops ops; /* for the hash lists */ > void *private; > + int idx; > }; > > /* > @@ -1104,6 +1106,11 @@ extern int > function_graph_enter(unsigned long ret, unsigned long func, > unsigned long frame_pointer, unsigned long *retp); > > +extern int > +function_graph_enter_ops(unsigned long ret, unsigned long func, > + unsigned long frame_pointer, unsigned long *retp, > + struct fgraph_ops *gops); > + > struct ftrace_ret_stack * > ftrace_graph_get_ret_stack(struct task_struct *task, int idx); > > diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c > index 62c35d6d95f9..6f537ebd3ed7 100644 > --- a/kernel/trace/fgraph.c > +++ b/kernel/trace/fgraph.c > @@ -7,6 +7,7 @@ > * > * Highly modified by Steven Rostedt (VMware). > */ > +#include > #include > #include > #include > @@ -17,22 +18,15 @@ > #include "ftrace_internal.h" > #include "trace.h" > > -#ifdef CONFIG_DYNAMIC_FTRACE > -#define ASSIGN_OPS_HASH(opsname, val) \ > - .func_hash = val, \ > - .local_hash.regex_lock = __MUTEX_INITIALIZER(opsname.local_hash.regex_lock), > -#else > -#define ASSIGN_OPS_HASH(opsname, val) > -#endif > - > #define FGRAPH_RET_SIZE sizeof(struct ftrace_ret_stack) > #define FGRAPH_RET_INDEX (FGRAPH_RET_SIZE / sizeof(long)) > > /* > * On entry to a function (via function_graph_enter()), a new ftrace_ret_stack > - * is allocated on the task's ret_stack, then each fgraph_ops on the > - * fgraph_array[]'s entryfunc is called and if that returns non-zero, the > - * index into the fgraph_array[] for that fgraph_ops is added to the ret_stack. > + * is allocated on the task's ret_stack with indexes entry, then each > + * fgraph_ops on the fgraph_array[]'s entryfunc is called and if that returns > + * non-zero, the index into the fgraph_array[] for that fgraph_ops is recorded > + * on the indexes entry as a bit flag. > * As the associated ftrace_ret_stack saved for those fgraph_ops needs to > * be found, the index to it is also added to the ret_stack along with the > * index of the fgraph_array[] to each fgraph_ops that needs their retfunc > @@ -42,61 +36,59 @@ > * to the last ftrace_ret_stack saved. All references to the > * ftrace_ret_stack has the format of: > * > - * bits: 0 - 13 Index in words from the previous ftrace_ret_stack > - * bits: 14 - 15 Type of storage > + * bits: 0 - 9 offset in words from the previous ftrace_ret_stack > + * (bitmap type should have FGRAPH_RET_INDEX always) > + * bits: 10 - 11 Type of storage > * 0 - reserved > - * 1 - fgraph_array index > - * For fgraph_array_index: > - * bits: 16 - 23 The fgraph_ops fgraph_array index > + * 1 - bitmap of fgraph_array index > + * > + * For bitmap of fgraph_array index > + * bits: 12 - 27 The bitmap of fgraph_ops fgraph_array index > * > * 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) > * > - * | | <- task->curr_ret_stack > - * +----------------------------------+ > - * | (3 << FGRAPH_ARRAY_SHIFT)|(2) | ( 3 for index of fourth fgraph_ops) > - * +----------------------------------+ > - * | (0 << FGRAPH_ARRAY_SHIFT)|(1) | ( 0 for index of first fgraph_ops) > - * +----------------------------------+ > - * | struct ftrace_ret_stack | > - * | (stores the saved ret pointer) | > - * +----------------------------------+ > - * | (X) | (N) | ( N words away from previous ret_stack) > - * | | > + * | | <- task->curr_ret_stack > + * +--------------------------------------------+ > + * | bitmap_type(bitmap:(BIT(3)|BIT(0)), | > + * | offset:FGRAPH_RET_INDEX) | <- the offset is from here > + * +--------------------------------------------+ > + * | struct ftrace_ret_stack | > + * | (stores the saved ret pointer) | <- the offset points here > + * +--------------------------------------------+ > + * | (X) | (N) | ( N words away from > + * | | previous ret_stack) > * > * If a backtrace is required, and the real return pointer needs to be > * fetched, then it looks at the task's curr_ret_stack index, if it > - * is greater than zero, it would subtact one, and then mask the value > - * on the ret_stack by FGRAPH_RET_INDEX_MASK and subtract FGRAPH_RET_INDEX > - * from that, to get the index of the ftrace_ret_stack structure stored > - * on the shadow stack. > + * is greater than zero (reserved, or right before poped), it would mask > + * the value by FGRAPH_RET_INDEX_MASK to get the offset index of the > + * ftrace_ret_stack structure stored on the shadow stack. > */ > > -#define FGRAPH_RET_INDEX_SIZE 14 > -#define FGRAPH_RET_INDEX_MASK ((1 << FGRAPH_RET_INDEX_SIZE) - 1) > - > +#define FGRAPH_RET_INDEX_SIZE 10 > +#define FGRAPH_RET_INDEX_MASK GENMASK(FGRAPH_RET_INDEX_SIZE - 1, 0) > > #define FGRAPH_TYPE_SIZE 2 > -#define FGRAPH_TYPE_MASK ((1 << FGRAPH_TYPE_SIZE) - 1) > +#define FGRAPH_TYPE_MASK GENMASK(FGRAPH_TYPE_SIZE - 1, 0) > #define FGRAPH_TYPE_SHIFT FGRAPH_RET_INDEX_SIZE > > enum { > FGRAPH_TYPE_RESERVED = 0, > - FGRAPH_TYPE_ARRAY = 1, > + FGRAPH_TYPE_BITMAP = 1, > }; > > -#define FGRAPH_ARRAY_SIZE 16 > -#define FGRAPH_ARRAY_MASK ((1 << FGRAPH_ARRAY_SIZE) - 1) > -#define FGRAPH_ARRAY_SHIFT (FGRAPH_TYPE_SHIFT + FGRAPH_TYPE_SIZE) > +#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_ARRAY_SIZE > +#define FGRAPH_MAX_INDEX (FGRAPH_INDEX_SIZE + FGRAPH_RET_INDEX) > + > +#define FGRAPH_ARRAY_SIZE FGRAPH_INDEX_SIZE > > -#define FGRAPH_FRAME_SIZE (FGRAPH_RET_SIZE + FGRAPH_ARRAY_SIZE * (sizeof(long))) > -#define FGRAPH_FRAME_INDEX (ALIGN(FGRAPH_FRAME_SIZE, \ > - sizeof(long)) / sizeof(long)) > #define SHADOW_STACK_SIZE (PAGE_SIZE) > #define SHADOW_STACK_INDEX (SHADOW_STACK_SIZE / sizeof(long)) > /* Leave on a buffer at the end */ > @@ -113,19 +105,36 @@ static struct fgraph_ops *fgraph_array[FGRAPH_ARRAY_SIZE]; > > static inline int get_ret_stack_index(struct task_struct *t, int offset) > { > - return current->ret_stack[offset] & FGRAPH_RET_INDEX_MASK; > + return t->ret_stack[offset] & FGRAPH_RET_INDEX_MASK; > } > > static inline int get_fgraph_type(struct task_struct *t, int offset) > { > - return (current->ret_stack[offset] >> FGRAPH_TYPE_SHIFT) & > - FGRAPH_TYPE_MASK; > + return (t->ret_stack[offset] >> FGRAPH_TYPE_SHIFT) & FGRAPH_TYPE_MASK; > +} > + > +static inline unsigned long > +get_fgraph_index_bitmap(struct task_struct *t, int offset) > +{ > + return (t->ret_stack[offset] >> FGRAPH_INDEX_SHIFT) & FGRAPH_INDEX_MASK; > } > > -static inline int get_fgraph_array(struct task_struct *t, int offset) > +static inline void > +set_fgraph_index_bitmap(struct task_struct *t, int offset, unsigned long bitmap) > { > - return (current->ret_stack[offset] >> FGRAPH_ARRAY_SHIFT) & > - FGRAPH_ARRAY_MASK; > + t->ret_stack[offset] = (bitmap << FGRAPH_INDEX_SHIFT) | > + (FGRAPH_TYPE_BITMAP << FGRAPH_TYPE_SHIFT) | FGRAPH_RET_INDEX; > +} > + > +static inline bool is_fgraph_index_set(struct task_struct *t, int offset, int idx) > +{ > + return !!(get_fgraph_index_bitmap(t, offset) & BIT(idx)); > +} > + > +static inline void > +add_fgraph_index_bitmap(struct task_struct *t, int offset, unsigned long bitmap) > +{ > + t->ret_stack[offset] |= (bitmap << FGRAPH_INDEX_SHIFT); > } > > /* ftrace_graph_entry set to this to tell some archs to run function graph */ > @@ -160,17 +169,14 @@ get_ret_stack(struct task_struct *t, int offset, int *index) > > BUILD_BUG_ON(FGRAPH_RET_SIZE % sizeof(long)); > > - if (offset <= 0) > + if (unlikely(offset <= 0)) > return NULL; > > - idx = get_ret_stack_index(t, offset - 1); > - > - if (idx <= 0 || idx > FGRAPH_MAX_INDEX) > + idx = get_ret_stack_index(t, --offset); > + if (WARN_ON_ONCE(idx <= 0 || idx > offset)) > return NULL; > > - offset -= idx + FGRAPH_RET_INDEX; > - if (offset < 0) > - return NULL; > + offset -= idx; > > *index = offset; > return RET_STACK(t, offset); > @@ -231,10 +237,12 @@ void ftrace_graph_stop(void) > /* Add a function return address to the trace stack on thread info.*/ > static int > ftrace_push_return_trace(unsigned long ret, unsigned long func, > - unsigned long frame_pointer, unsigned long *retp) > + unsigned long frame_pointer, unsigned long *retp, > + int fgraph_idx) > { > struct ftrace_ret_stack *ret_stack; > unsigned long long calltime; > + unsigned long val; > int index; > > if (unlikely(ftrace_graph_is_dead())) > @@ -243,6 +251,21 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, > if (!current->ret_stack) > return -EBUSY; > > + /* > + * At first, check whether the previous fgraph callback is pushed by > + * the fgraph on the same function entry. > + * But if @func is the self tail-call function, we also need to ensure > + * the ret_stack is not for the previous call by checking whether the > + * bit of @fgraph_idx is set or not. > + */ > + ret_stack = get_ret_stack(current, current->curr_ret_stack, &index); > + if (ret_stack && ret_stack->func == func && > + get_fgraph_type(current, index + FGRAPH_RET_INDEX) == FGRAPH_TYPE_BITMAP && > + !is_fgraph_index_set(current, index + FGRAPH_RET_INDEX, fgraph_idx)) > + return index + FGRAPH_RET_INDEX; > + > + val = (FGRAPH_TYPE_RESERVED << FGRAPH_TYPE_SHIFT) | FGRAPH_RET_INDEX; > + > BUILD_BUG_ON(SHADOW_STACK_SIZE % sizeof(long)); > > /* > @@ -252,17 +275,19 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, > smp_rmb(); > > /* The return trace stack is full */ > - if (current->curr_ret_stack >= SHADOW_STACK_MAX_INDEX) { > + if (current->curr_ret_stack + FGRAPH_RET_INDEX >= SHADOW_STACK_MAX_INDEX) { > atomic_inc(¤t->trace_overrun); > return -EBUSY; > } > > calltime = trace_clock_local(); > > - index = current->curr_ret_stack; > - /* ret offset = 1 ; type = reserved */ > - current->ret_stack[index + FGRAPH_RET_INDEX] = 1; > + index = READ_ONCE(current->curr_ret_stack); > ret_stack = RET_STACK(current, index); > + index += FGRAPH_RET_INDEX; > + > + /* ret offset = FGRAPH_RET_INDEX ; type = reserved */ > + current->ret_stack[index] = val; > ret_stack->ret = ret; > /* > * The unwinders expect curr_ret_stack to point to either zero > @@ -278,7 +303,7 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, > * at least a correct index! > */ > barrier(); > - current->curr_ret_stack += FGRAPH_RET_INDEX + 1; > + current->curr_ret_stack = index + 1; > /* > * This next barrier is to ensure that an interrupt coming in > * will not corrupt what we are about to write. > @@ -286,7 +311,7 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, > barrier(); > > /* Still keep it reserved even if an interrupt came in */ > - current->ret_stack[index + FGRAPH_RET_INDEX] = 1; > + current->ret_stack[index] = val; > > ret_stack->ret = ret; > ret_stack->func = func; > @@ -297,7 +322,7 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, > #ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR > ret_stack->retp = retp; > #endif > - return 0; > + return index; > } > > /* > @@ -314,15 +339,13 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, > # define MCOUNT_INSN_SIZE 0 > #endif > > +/* If the caller does not use ftrace, call this function. */ > int function_graph_enter(unsigned long ret, unsigned long func, > unsigned long frame_pointer, unsigned long *retp) > { > struct ftrace_graph_ent trace; > - int offset; > - int start; > - int type; > - int val; > - int cnt = 0; > + unsigned long bitmap = 0; > + int index; > int i; > > #ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS > @@ -337,69 +360,33 @@ int function_graph_enter(unsigned long ret, unsigned long func, > return -EBUSY; > #endif > > - if (!ftrace_ops_test(&global_ops, func, NULL)) > - return -EBUSY; > - > trace.func = func; > trace.depth = ++current->curr_ret_depth; > > - if (ftrace_push_return_trace(ret, func, frame_pointer, retp)) > + index = ftrace_push_return_trace(ret, func, frame_pointer, retp, 0); > + if (index < 0) > goto out; > > - /* Use start for the distance to ret_stack (skipping over reserve) */ > - start = offset = current->curr_ret_stack - 2; > - > for (i = 0; i < fgraph_array_cnt; i++) { > struct fgraph_ops *gops = fgraph_array[i]; > > if (gops == &fgraph_stub) > continue; > > - if ((offset == start) && > - (current->curr_ret_stack >= SHADOW_STACK_INDEX - 1)) { > - atomic_inc(¤t->trace_overrun); > - break; > - } > - if (fgraph_array[i]->entryfunc(&trace, fgraph_array[i])) { > - offset = current->curr_ret_stack; > - /* Check the top level stored word */ > - type = get_fgraph_type(current, offset - 1); > - > - val = (i << FGRAPH_ARRAY_SHIFT) | > - (FGRAPH_TYPE_ARRAY << FGRAPH_TYPE_SHIFT) | > - ((offset - start) - 1); > - > - /* We can reuse the top word if it is reserved */ > - if (type == FGRAPH_TYPE_RESERVED) { > - current->ret_stack[offset - 1] = val; > - cnt++; > - continue; > - } > - val++; > - > - current->ret_stack[offset] = val; > - /* > - * Write the value before we increment, so that > - * if an interrupt comes in after we increment > - * it will still see the value and skip over > - * this. > - */ > - barrier(); > - current->curr_ret_stack++; > - /* > - * Have to write again, in case an interrupt > - * came in before the increment and after we > - * wrote the value. > - */ > - barrier(); > - current->ret_stack[offset] = val; > - cnt++; > - } > + if (ftrace_ops_test(&gops->ops, func, NULL) && > + gops->entryfunc(&trace, gops)) > + bitmap |= BIT(i); > } > > - if (!cnt) > + if (!bitmap) > goto out_ret; > > + /* > + * Since this function uses fgraph_idx = 0 as a tail-call checking > + * flag, set that bit always. > + */ > + set_fgraph_index_bitmap(current, index, bitmap | BIT(0)); > + > return 0; > out_ret: > current->curr_ret_stack -= FGRAPH_RET_INDEX + 1; > @@ -408,15 +395,51 @@ int function_graph_enter(unsigned long ret, unsigned long func, > return -EBUSY; > } > > +/* This is called from ftrace_graph_func() via ftrace */ > +int function_graph_enter_ops(unsigned long ret, unsigned long func, > + unsigned long frame_pointer, unsigned long *retp, > + struct fgraph_ops *gops) > +{ > + struct ftrace_graph_ent trace; > + int index; > + int type; > + > + > + /* Use start for the distance to ret_stack (skipping over reserve) */ > + index = ftrace_push_return_trace(ret, func, frame_pointer, retp, gops->idx); > + if (index < 0) > + return index; > + type = get_fgraph_type(current, index); > + > + /* This is the first ret_stack for this fentry */ > + if (type == FGRAPH_TYPE_RESERVED) > + ++current->curr_ret_depth; > + > + trace.func = func; > + trace.depth = current->curr_ret_depth; > + 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; > + } > + > + if (type == FGRAPH_TYPE_RESERVED) { > + current->curr_ret_stack -= FGRAPH_RET_INDEX + 1; > + current->curr_ret_depth--; > + } > + return -EBUSY; > +} > + > /* Retrieve a function return address to the trace stack on thread info.*/ > static struct ftrace_ret_stack * > ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret, > - unsigned long frame_pointer) > + unsigned long frame_pointer, int *index) > { > struct ftrace_ret_stack *ret_stack; > - int index; > > - ret_stack = get_ret_stack(current, current->curr_ret_stack, &index); > + ret_stack = get_ret_stack(current, current->curr_ret_stack, index); > > if (unlikely(!ret_stack)) { > ftrace_graph_stop(); > @@ -455,6 +478,7 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret, > } > #endif > > + *index += FGRAPH_RET_INDEX; > *ret = ret_stack->ret; > trace->func = ret_stack->func; > trace->calltime = ret_stack->calltime; > @@ -507,13 +531,12 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs > { > struct ftrace_ret_stack *ret_stack; > struct ftrace_graph_ret trace; > + unsigned long bitmap; > unsigned long ret; > - int offset; > int index; > - int idx; > int i; > > - ret_stack = ftrace_pop_return_trace(&trace, &ret, frame_pointer); > + ret_stack = ftrace_pop_return_trace(&trace, &ret, frame_pointer, &index); > > if (unlikely(!ret_stack)) { > ftrace_graph_stop(); > @@ -527,16 +550,17 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs > trace.retval = fgraph_ret_regs_return_value(ret_regs); > #endif > > - offset = current->curr_ret_stack - 1; > - index = get_ret_stack_index(current, offset); > + bitmap = get_fgraph_index_bitmap(current, index); > + for (i = 0; i < FGRAPH_ARRAY_SIZE; i++) { > + struct fgraph_ops *gops = fgraph_array[i]; > > - /* index has to be at least one! Optimize for it */ > - i = 0; > - do { > - idx = get_fgraph_array(current, offset - i); > - fgraph_array[idx]->retfunc(&trace, fgraph_array[idx]); > - i++; > - } while (i < index); > + if (!(bitmap & BIT(i))) > + continue; > + if (gops == &fgraph_stub) > + continue; > + > + gops->retfunc(&trace, gops); > + } > > /* > * The ftrace_graph_return() may still access the current > @@ -544,7 +568,7 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs > * curr_ret_stack is after that. > */ > barrier(); > - current->curr_ret_stack -= index + FGRAPH_RET_INDEX; > + current->curr_ret_stack -= FGRAPH_RET_INDEX + 1; > current->curr_ret_depth--; > return ret; > } > @@ -622,7 +646,17 @@ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx, > ret_stack = get_ret_stack(current, i, &i); > if (!ret_stack) > break; > - if (ret_stack->retp == retp) > + /* > + * For the tail-call, there would be 2 or more ftrace_ret_stacks on > + * the ret_stack, which records "return_to_handler" as the return > + * address excpt for the last one. > + * But on the real stack, there should be 1 entry because tail-call > + * reuses the return address on the stack and jump to the next function. > + * Thus we will continue to find real return address. > + */ > + if (ret_stack->retp == retp && > + ret_stack->ret != > + (unsigned long)dereference_kernel_function_descriptor(return_to_handler)) > return ret_stack->ret; > } > > @@ -645,6 +679,9 @@ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx, > i = *idx; > do { > ret_stack = get_ret_stack(task, task_idx, &task_idx); > + if (ret_stack && ret_stack->ret == > + (unsigned long)dereference_kernel_function_descriptor(return_to_handler)) > + continue; > i--; > } while (i >= 0 && ret_stack); > > @@ -655,17 +692,25 @@ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx, > } > #endif /* HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */ > > -static struct ftrace_ops graph_ops = { > - .func = ftrace_graph_func, > - .flags = FTRACE_OPS_FL_INITIALIZED | > - FTRACE_OPS_FL_PID | > - FTRACE_OPS_GRAPH_STUB, > +void fgraph_init_ops(struct ftrace_ops *dst_ops, > + struct ftrace_ops *src_ops) > +{ > + dst_ops->func = ftrace_graph_func; > + dst_ops->flags = FTRACE_OPS_FL_PID | FTRACE_OPS_GRAPH_STUB; > + > #ifdef FTRACE_GRAPH_TRAMP_ADDR > - .trampoline = FTRACE_GRAPH_TRAMP_ADDR, > + dst_ops->trampoline = FTRACE_GRAPH_TRAMP_ADDR; > /* trampoline_size is only needed for dynamically allocated tramps */ > #endif > - ASSIGN_OPS_HASH(graph_ops, &global_ops.local_hash) > -}; > + > +#ifdef CONFIG_DYNAMIC_FTRACE > + if (src_ops) { > + dst_ops->func_hash = &src_ops->local_hash; > + mutex_init(&dst_ops->local_hash.regex_lock); > + dst_ops->flags |= FTRACE_OPS_FL_INITIALIZED; > + } > +#endif > +} > > void ftrace_graph_sleep_time_control(bool enable) > { > @@ -869,11 +914,20 @@ static int start_graph_tracing(void) > > int register_ftrace_graph(struct fgraph_ops *gops) > { > + int command = 0; > int ret = 0; > int i; > > mutex_lock(&ftrace_lock); > > + if (!gops->ops.func) { > + gops->ops.flags |= FTRACE_OPS_GRAPH_STUB; > + gops->ops.func = ftrace_graph_func; > +#ifdef FTRACE_GRAPH_TRAMP_ADDR > + gops->ops.trampoline = FTRACE_GRAPH_TRAMP_ADDR; > +#endif > + } > + > if (!fgraph_array[0]) { > /* The array must always have real data on it */ > for (i = 0; i < FGRAPH_ARRAY_SIZE; i++) > @@ -893,6 +947,7 @@ int register_ftrace_graph(struct fgraph_ops *gops) > fgraph_array[i] = gops; > if (i + 1 > fgraph_array_cnt) > fgraph_array_cnt = i + 1; > + gops->idx = i; > > ftrace_graph_active++; > > @@ -909,9 +964,10 @@ int register_ftrace_graph(struct fgraph_ops *gops) > */ > ftrace_graph_return = return_run; > ftrace_graph_entry = entry_run; > - > - ret = ftrace_startup(&graph_ops, FTRACE_START_FUNC_RET); > + command = FTRACE_START_FUNC_RET; > } > + > + ret = ftrace_startup(&gops->ops, command); > out: > mutex_unlock(&ftrace_lock); > return ret; > @@ -919,6 +975,7 @@ int register_ftrace_graph(struct fgraph_ops *gops) > > void unregister_ftrace_graph(struct fgraph_ops *gops) > { > + int command = 0; > int i; > > mutex_lock(&ftrace_lock); > @@ -926,25 +983,29 @@ void unregister_ftrace_graph(struct fgraph_ops *gops) > if (unlikely(!ftrace_graph_active)) > goto out; > > - for (i = 0; i < fgraph_array_cnt; i++) > - if (gops == fgraph_array[i]) > - break; > - if (i >= fgraph_array_cnt) > + if (unlikely(gops->idx < 0 || gops->idx >= fgraph_array_cnt)) > goto out; > > - fgraph_array[i] = &fgraph_stub; > - if (i + 1 == fgraph_array_cnt) { > - for (; i >= 0; i--) > - if (fgraph_array[i] != &fgraph_stub) > - break; > + WARN_ON_ONCE(fgraph_array[gops->idx] != gops); > + > + fgraph_array[gops->idx] = &fgraph_stub; > + if (gops->idx + 1 == fgraph_array_cnt) { > + i = gops->idx; > + while (i >= 0 && fgraph_array[i] == &fgraph_stub) > + i--; > fgraph_array_cnt = i + 1; > } > > ftrace_graph_active--; > + > + if (!ftrace_graph_active) > + command = FTRACE_STOP_FUNC_RET; > + > + ftrace_shutdown(&gops->ops, command); > + > if (!ftrace_graph_active) { > ftrace_graph_return = ftrace_stub_graph; > ftrace_graph_entry = ftrace_graph_entry_stub; > - ftrace_shutdown(&graph_ops, FTRACE_STOP_FUNC_RET); > unregister_pm_notifier(&ftrace_suspend_notifier); > unregister_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL); > } > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index 83fbfb7b48f8..c4cc2a9d0047 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -3050,6 +3050,8 @@ int ftrace_startup(struct ftrace_ops *ops, int command) > if (unlikely(ftrace_disabled)) > return -ENODEV; > > + ftrace_ops_init(ops); > + > ret = __register_ftrace_function(ops); > if (ret) > return ret; > @@ -7319,7 +7321,7 @@ __init void ftrace_init_global_array_ops(struct trace_array *tr) > tr->ops = &global_ops; > tr->ops->private = tr; > ftrace_init_trace_array(tr); > - init_array_fgraph_ops(tr); > + init_array_fgraph_ops(tr, tr->ops); > } > > void ftrace_init_array_ops(struct trace_array *tr, ftrace_func_t func) > @@ -8051,7 +8053,7 @@ static int register_ftrace_function_nolock(struct ftrace_ops *ops) > */ > int register_ftrace_function(struct ftrace_ops *ops) > { > - int ret; > + int ret = -1; > > lock_direct_mutex(); > ret = prepare_direct_functions_for_ipmodify(ops); > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h > index 16948c0ed00a..02edfdb68933 100644 > --- a/kernel/trace/trace.h > +++ b/kernel/trace/trace.h > @@ -890,8 +890,8 @@ extern int __trace_graph_entry(struct trace_array *tr, > extern void __trace_graph_return(struct trace_array *tr, > struct ftrace_graph_ret *trace, > unsigned int trace_ctx); > -extern void init_array_fgraph_ops(struct trace_array *tr); > -extern int allocate_fgraph_ops(struct trace_array *tr); > +extern void init_array_fgraph_ops(struct trace_array *tr, struct ftrace_ops *ops); > +extern int allocate_fgraph_ops(struct trace_array *tr, struct ftrace_ops *ops); > extern void free_fgraph_ops(struct trace_array *tr); > > #ifdef CONFIG_DYNAMIC_FTRACE > @@ -974,6 +974,7 @@ static inline int ftrace_graph_notrace_addr(unsigned long addr) > preempt_enable_notrace(); > return ret; > } > + > #else > static inline int ftrace_graph_addr(struct ftrace_graph_ent *trace) > { > @@ -999,18 +1000,19 @@ static inline bool ftrace_graph_ignore_func(struct ftrace_graph_ent *trace) > (fgraph_max_depth && trace->depth >= fgraph_max_depth); > } > > +void fgraph_init_ops(struct ftrace_ops *dst_ops, > + struct ftrace_ops *src_ops); > + > #else /* CONFIG_FUNCTION_GRAPH_TRACER */ > static inline enum print_line_t > print_graph_function_flags(struct trace_iterator *iter, u32 flags) > { > return TRACE_TYPE_UNHANDLED; > } > -static inline void init_array_fgraph_ops(struct trace_array *tr) { } > -static inline int allocate_fgraph_ops(struct trace_array *tr) > -{ > - return 0; > -} > static inline void free_fgraph_ops(struct trace_array *tr) { } > +/* ftrace_ops may not be defined */ > +#define init_array_fgraph_ops(tr, ops) do { } while (0) > +#define allocate_fgraph_ops(tr, ops) ({ 0; }) > #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ > > extern struct list_head ftrace_pids; > diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c > index 8e8da0d0ee52..13bf2415245d 100644 > --- a/kernel/trace/trace_functions.c > +++ b/kernel/trace/trace_functions.c > @@ -91,7 +91,7 @@ int ftrace_create_function_files(struct trace_array *tr, > if (!tr->ops) > return -EINVAL; > > - ret = allocate_fgraph_ops(tr); > + ret = allocate_fgraph_ops(tr, tr->ops); > if (ret) { > kfree(tr->ops); > return ret; > diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c > index 9ccc904a7703..7f30652f0e97 100644 > --- a/kernel/trace/trace_functions_graph.c > +++ b/kernel/trace/trace_functions_graph.c > @@ -288,7 +288,7 @@ static struct fgraph_ops funcgraph_ops = { > .retfunc = &trace_graph_return, > }; > > -int allocate_fgraph_ops(struct trace_array *tr) > +int allocate_fgraph_ops(struct trace_array *tr, struct ftrace_ops *ops) > { > struct fgraph_ops *gops; > > @@ -301,6 +301,9 @@ int allocate_fgraph_ops(struct trace_array *tr) > > tr->gops = gops; > gops->private = tr; > + > + fgraph_init_ops(&gops->ops, ops); > + > return 0; > } > > @@ -309,10 +312,11 @@ void free_fgraph_ops(struct trace_array *tr) > kfree(tr->gops); > } > > -__init void init_array_fgraph_ops(struct trace_array *tr) > +__init void init_array_fgraph_ops(struct trace_array *tr, struct ftrace_ops *ops) > { > tr->gops = &funcgraph_ops; > funcgraph_ops.private = tr; > + fgraph_init_ops(&tr->gops->ops, ops); > } > > static int graph_trace_init(struct trace_array *tr) >