From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 21155C433F5 for ; Thu, 30 Sep 2021 08:28:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E787C615E5 for ; Thu, 30 Sep 2021 08:28:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348274AbhI3I34 (ORCPT ); Thu, 30 Sep 2021 04:29:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35250 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348109AbhI3I34 (ORCPT ); Thu, 30 Sep 2021 04:29:56 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 826ADC06161C; Thu, 30 Sep 2021 01:28:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=+L12sTTirMmOEVfxeyEGi5LQTEZvYrWzWkQwzAhxwkg=; b=OujGqol3VJa/GixiJqWuCxtHmI RPdfebF2NWO2yZnEaDh7ToE4VwUCUNrlk556tz6DMsnw2u+LEC6IyBkqi36oj/quB40JIDmsS23Hf cqgQRwR+eQu6yYZFowjF9CgOG80LJFMzcCzgNVoOkaIBE1OiWTMYTqQ0cFU2F8eMQ1HbMVvoGO37z oK5U7yx9YHODvwWjjuY7nw7paR1N9EbUgzlN5mvtAqSEK62hiLjZ5ca+UzxPrgnZz3lkMEaNuzSnu vXHTkdZfpbbWBky55tV4BQ2yyu2kxEjunJZJ7pg/Uyg7ST8jGK6xUNoB/dwcXTVzqxYPyQ1jIhiSY VHc8rWuw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mVrPL-006ukp-Hc; Thu, 30 Sep 2021 08:27:11 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 74707300268; Thu, 30 Sep 2021 10:27:07 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 5693B266411AD; Thu, 30 Sep 2021 10:27:07 +0200 (CEST) Date: Thu, 30 Sep 2021 10:27:07 +0200 From: Peter Zijlstra To: Kees Cook Cc: Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , kernel test robot , Vito Caputo , Jann Horn , Andrew Morton , Christian Brauner , Anand K Mistry , "Kenta.Tada@sony.com" , Alexey Gladkov , Michael =?iso-8859-1?Q?Wei=DF?= , Michal Hocko , Helge Deller , Qi Zheng , "Tobin C. Harding" , Tycho Andersen , Thomas Gleixner , Borislav Petkov , "H. Peter Anvin" , Mark Rutland , Jens Axboe , Stefan Metzmacher , Lai Jiangshan , Andy Lutomirski , Dave Hansen , "Eric W. Biederman" , Ohhoon Kwon , Kalesh Singh , YiFei Zhu , Josh Poimboeuf , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-hardening@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH v2 2/6] sched: Add wrapper for get_wchan() to keep task blocked Message-ID: References: <20210929220218.691419-1-keescook@chromium.org> <20210929220218.691419-3-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210929220218.691419-3-keescook@chromium.org> Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org On Wed, Sep 29, 2021 at 03:02:14PM -0700, Kees Cook wrote: > Having a stable wchan means the process must be blocked and for it to > stay that way while performing stack unwinding. How's this instead? --- Subject: sched: Wrap get_wchan() to keep task blocked From: Kees Cook Date: Wed, 29 Sep 2021 15:02:14 -0700 From: Kees Cook Having a stable wchan means the process must be blocked and for it to stay that way while performing stack unwinding. Suggested-by: Peter Zijlstra Signed-off-by: Kees Cook [peterz: __get_wchan] Signed-off-by: Peter Zijlstra (Intel) --- arch/alpha/include/asm/processor.h | 2 +- arch/alpha/kernel/process.c | 5 ++--- arch/arc/include/asm/processor.h | 2 +- arch/arc/kernel/stacktrace.c | 4 ++-- arch/arm/include/asm/processor.h | 2 +- arch/arm/kernel/process.c | 4 +--- arch/arm64/include/asm/processor.h | 2 +- arch/arm64/kernel/process.c | 4 +--- arch/csky/include/asm/processor.h | 2 +- arch/csky/kernel/stacktrace.c | 5 ++--- arch/h8300/include/asm/processor.h | 2 +- arch/h8300/kernel/process.c | 5 +---- arch/hexagon/include/asm/processor.h | 2 +- arch/hexagon/kernel/process.c | 4 +--- arch/ia64/include/asm/processor.h | 2 +- arch/ia64/kernel/process.c | 5 +---- arch/m68k/include/asm/processor.h | 2 +- arch/m68k/kernel/process.c | 4 +--- arch/microblaze/include/asm/processor.h | 2 +- arch/microblaze/kernel/process.c | 2 +- arch/mips/include/asm/processor.h | 2 +- arch/mips/kernel/process.c | 8 +++----- arch/nds32/include/asm/processor.h | 2 +- arch/nds32/kernel/process.c | 7 +------ arch/nios2/include/asm/processor.h | 2 +- arch/nios2/kernel/process.c | 5 +---- arch/openrisc/include/asm/processor.h | 2 +- arch/openrisc/kernel/process.c | 2 +- arch/parisc/include/asm/processor.h | 2 +- arch/parisc/kernel/process.c | 5 +---- arch/powerpc/include/asm/processor.h | 2 +- arch/powerpc/kernel/process.c | 9 +++------ arch/riscv/include/asm/processor.h | 2 +- arch/riscv/kernel/stacktrace.c | 12 +++++------- arch/s390/include/asm/processor.h | 2 +- arch/s390/kernel/process.c | 4 ++-- arch/sh/include/asm/processor_32.h | 2 +- arch/sh/kernel/process_32.c | 5 +---- arch/sparc/include/asm/processor_32.h | 2 +- arch/sparc/include/asm/processor_64.h | 2 +- arch/sparc/kernel/process_32.c | 5 +---- arch/sparc/kernel/process_64.c | 5 +---- arch/um/include/asm/processor-generic.h | 2 +- arch/um/kernel/process.c | 5 +---- arch/x86/include/asm/processor.h | 2 +- arch/x86/kernel/process.c | 5 +---- arch/xtensa/include/asm/processor.h | 2 +- arch/xtensa/kernel/process.c | 5 +---- include/linux/sched.h | 1 + kernel/sched/core.c | 19 +++++++++++++++++++ 50 files changed, 80 insertions(+), 112 deletions(-) --- a/arch/alpha/include/asm/processor.h +++ b/arch/alpha/include/asm/processor.h @@ -42,7 +42,7 @@ extern void start_thread(struct pt_regs struct task_struct; extern void release_thread(struct task_struct *); -unsigned long get_wchan(struct task_struct *p); +unsigned long __get_wchan(struct task_struct *p); #define KSTK_EIP(tsk) (task_pt_regs(tsk)->pc) --- a/arch/alpha/kernel/process.c +++ b/arch/alpha/kernel/process.c @@ -376,12 +376,11 @@ thread_saved_pc(struct task_struct *t) } unsigned long -get_wchan(struct task_struct *p) +__get_wchan(struct task_struct *p) { unsigned long schedule_frame; unsigned long pc; - if (!p || p == current || task_is_running(p)) - return 0; + /* * This one depends on the frame size of schedule(). Do a * "disass schedule" in gdb to find the frame size. Also, the --- a/arch/arc/include/asm/processor.h +++ b/arch/arc/include/asm/processor.h @@ -70,7 +70,7 @@ struct task_struct; extern void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long usp); -extern unsigned int get_wchan(struct task_struct *p); +extern unsigned int __get_wchan(struct task_struct *p); #endif /* !__ASSEMBLY__ */ --- a/arch/arc/kernel/stacktrace.c +++ b/arch/arc/kernel/stacktrace.c @@ -15,7 +15,7 @@ * = specifics of data structs where trace is saved(CONFIG_STACKTRACE etc) * * vineetg: March 2009 - * -Implemented correct versions of thread_saved_pc() and get_wchan() + * -Implemented correct versions of thread_saved_pc() and __get_wchan() * * rajeshwarr: 2008 * -Initial implementation @@ -248,7 +248,7 @@ void show_stack(struct task_struct *tsk, * Of course just returning schedule( ) would be pointless so unwind until * the function is not in schedular code */ -unsigned int get_wchan(struct task_struct *tsk) +unsigned int __get_wchan(struct task_struct *tsk) { return arc_unwind_core(tsk, NULL, __get_first_nonsched, NULL); } --- a/arch/arm/include/asm/processor.h +++ b/arch/arm/include/asm/processor.h @@ -84,7 +84,7 @@ struct task_struct; /* Free all resources held by a thread. */ extern void release_thread(struct task_struct *); -unsigned long get_wchan(struct task_struct *p); +unsigned long __get_wchan(struct task_struct *p); #define task_pt_regs(p) \ ((struct pt_regs *)(THREAD_START_SP + task_stack_page(p)) - 1) --- a/arch/arm/kernel/process.c +++ b/arch/arm/kernel/process.c @@ -276,13 +276,11 @@ int copy_thread(unsigned long clone_flag return 0; } -unsigned long get_wchan(struct task_struct *p) +unsigned long __get_wchan(struct task_struct *p) { struct stackframe frame; unsigned long stack_page; int count = 0; - if (!p || p == current || task_is_running(p)) - return 0; frame.fp = thread_saved_fp(p); frame.sp = thread_saved_sp(p); --- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -257,7 +257,7 @@ struct task_struct; /* Free all resources held by a thread. */ extern void release_thread(struct task_struct *); -unsigned long get_wchan(struct task_struct *p); +unsigned long __get_wchan(struct task_struct *p); void update_sctlr_el1(u64 sctlr); --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -528,13 +528,11 @@ __notrace_funcgraph struct task_struct * return last; } -unsigned long get_wchan(struct task_struct *p) +unsigned long __get_wchan(struct task_struct *p) { struct stackframe frame; unsigned long stack_page, ret = 0; int count = 0; - if (!p || p == current || task_is_running(p)) - return 0; stack_page = (unsigned long)try_get_task_stack(p); if (!stack_page) --- a/arch/csky/include/asm/processor.h +++ b/arch/csky/include/asm/processor.h @@ -81,7 +81,7 @@ static inline void release_thread(struct extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags); -unsigned long get_wchan(struct task_struct *p); +unsigned long __get_wchan(struct task_struct *p); #define KSTK_EIP(tsk) (task_pt_regs(tsk)->pc) #define KSTK_ESP(tsk) (task_pt_regs(tsk)->usp) --- a/arch/csky/kernel/stacktrace.c +++ b/arch/csky/kernel/stacktrace.c @@ -111,12 +111,11 @@ static bool save_wchan(unsigned long pc, return false; } -unsigned long get_wchan(struct task_struct *task) +unsigned long __get_wchan(struct task_struct *task) { unsigned long pc = 0; - if (likely(task && task != current && !task_is_running(task))) - walk_stackframe(task, NULL, save_wchan, &pc); + walk_stackframe(task, NULL, save_wchan, &pc); return pc; } --- a/arch/h8300/include/asm/processor.h +++ b/arch/h8300/include/asm/processor.h @@ -105,7 +105,7 @@ static inline void release_thread(struct { } -unsigned long get_wchan(struct task_struct *p); +unsigned long __get_wchan(struct task_struct *p); #define KSTK_EIP(tsk) \ ({ \ --- a/arch/h8300/kernel/process.c +++ b/arch/h8300/kernel/process.c @@ -128,15 +128,12 @@ int copy_thread(unsigned long clone_flag return 0; } -unsigned long get_wchan(struct task_struct *p) +unsigned long __get_wchan(struct task_struct *p) { unsigned long fp, pc; unsigned long stack_page; int count = 0; - if (!p || p == current || task_is_running(p)) - return 0; - stack_page = (unsigned long)p; fp = ((struct pt_regs *)p->thread.ksp)->er6; do { --- a/arch/hexagon/include/asm/processor.h +++ b/arch/hexagon/include/asm/processor.h @@ -64,7 +64,7 @@ struct thread_struct { extern void release_thread(struct task_struct *dead_task); /* Get wait channel for task P. */ -extern unsigned long get_wchan(struct task_struct *p); +extern unsigned long __get_wchan(struct task_struct *p); /* The following stuff is pretty HEXAGON specific. */ --- a/arch/hexagon/kernel/process.c +++ b/arch/hexagon/kernel/process.c @@ -130,13 +130,11 @@ void flush_thread(void) * is an identification of the point at which the scheduler * was invoked by a blocked thread. */ -unsigned long get_wchan(struct task_struct *p) +unsigned long __get_wchan(struct task_struct *p) { unsigned long fp, pc; unsigned long stack_page; int count = 0; - if (!p || p == current || task_is_running(p)) - return 0; stack_page = (unsigned long)task_stack_page(p); fp = ((struct hexagon_switch_stack *)p->thread.switch_sp)->fp; --- a/arch/ia64/include/asm/processor.h +++ b/arch/ia64/include/asm/processor.h @@ -330,7 +330,7 @@ struct task_struct; #define release_thread(dead_task) /* Get wait channel for task P. */ -extern unsigned long get_wchan (struct task_struct *p); +extern unsigned long __get_wchan (struct task_struct *p); /* Return instruction pointer of blocked task TSK. */ #define KSTK_EIP(tsk) \ --- a/arch/ia64/kernel/process.c +++ b/arch/ia64/kernel/process.c @@ -523,15 +523,12 @@ exit_thread (struct task_struct *tsk) } unsigned long -get_wchan (struct task_struct *p) +__get_wchan (struct task_struct *p) { struct unw_frame_info info; unsigned long ip; int count = 0; - if (!p || p == current || task_is_running(p)) - return 0; - /* * Note: p may not be a blocked task (it could be current or * another process running on some other CPU. Rather than --- a/arch/m68k/include/asm/processor.h +++ b/arch/m68k/include/asm/processor.h @@ -125,7 +125,7 @@ static inline void release_thread(struct { } -unsigned long get_wchan(struct task_struct *p); +unsigned long __get_wchan(struct task_struct *p); #define KSTK_EIP(tsk) \ ({ \ --- a/arch/m68k/kernel/process.c +++ b/arch/m68k/kernel/process.c @@ -263,13 +263,11 @@ int dump_fpu (struct pt_regs *regs, stru } EXPORT_SYMBOL(dump_fpu); -unsigned long get_wchan(struct task_struct *p) +unsigned long __get_wchan(struct task_struct *p) { unsigned long fp, pc; unsigned long stack_page; int count = 0; - if (!p || p == current || task_is_running(p)) - return 0; stack_page = (unsigned long)task_stack_page(p); fp = ((struct switch_stack *)p->thread.ksp)->a6; --- a/arch/microblaze/include/asm/processor.h +++ b/arch/microblaze/include/asm/processor.h @@ -68,7 +68,7 @@ static inline void release_thread(struct { } -unsigned long get_wchan(struct task_struct *p); +unsigned long __get_wchan(struct task_struct *p); /* The size allocated for kernel stacks. This _must_ be a power of two! */ # define KERNEL_STACK_SIZE 0x2000 --- a/arch/microblaze/kernel/process.c +++ b/arch/microblaze/kernel/process.c @@ -112,7 +112,7 @@ int copy_thread(unsigned long clone_flag return 0; } -unsigned long get_wchan(struct task_struct *p) +unsigned long __get_wchan(struct task_struct *p) { /* TBD (used by procfs) */ return 0; --- a/arch/mips/include/asm/processor.h +++ b/arch/mips/include/asm/processor.h @@ -369,7 +369,7 @@ static inline void flush_thread(void) { } -unsigned long get_wchan(struct task_struct *p); +unsigned long __get_wchan(struct task_struct *p); #define __KSTK_TOS(tsk) ((unsigned long)task_stack_page(tsk) + \ THREAD_SIZE - 32 - sizeof(struct pt_regs)) --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -511,7 +511,7 @@ static int __init frame_info_init(void) /* * Without schedule() frame info, result given by - * thread_saved_pc() and get_wchan() are not reliable. + * thread_saved_pc() and __get_wchan() are not reliable. */ if (schedule_mfi.pc_offset < 0) printk("Can't analyze schedule() prologue at %p\n", schedule); @@ -652,9 +652,9 @@ unsigned long unwind_stack(struct task_s #endif /* - * get_wchan - a maintenance nightmare^W^Wpain in the ass ... + * __get_wchan - a maintenance nightmare^W^Wpain in the ass ... */ -unsigned long get_wchan(struct task_struct *task) +unsigned long __get_wchan(struct task_struct *task) { unsigned long pc = 0; #ifdef CONFIG_KALLSYMS @@ -662,8 +662,6 @@ unsigned long get_wchan(struct task_stru unsigned long ra = 0; #endif - if (!task || task == current || task_is_running(task)) - goto out; if (!task_stack_page(task)) goto out; --- a/arch/nds32/include/asm/processor.h +++ b/arch/nds32/include/asm/processor.h @@ -83,7 +83,7 @@ extern struct task_struct *last_task_use /* Prepare to copy thread state - unlazy all lazy status */ #define prepare_to_copy(tsk) do { } while (0) -unsigned long get_wchan(struct task_struct *p); +unsigned long __get_wchan(struct task_struct *p); #define cpu_relax() barrier() --- a/arch/nds32/kernel/process.c +++ b/arch/nds32/kernel/process.c @@ -233,15 +233,12 @@ int dump_fpu(struct pt_regs *regs, elf_f EXPORT_SYMBOL(dump_fpu); -unsigned long get_wchan(struct task_struct *p) +unsigned long __get_wchan(struct task_struct *p) { unsigned long fp, lr; unsigned long stack_start, stack_end; int count = 0; - if (!p || p == current || task_is_running(p)) - return 0; - if (IS_ENABLED(CONFIG_FRAME_POINTER)) { stack_start = (unsigned long)end_of_stack(p); stack_end = (unsigned long)task_stack_page(p) + THREAD_SIZE; @@ -258,5 +255,3 @@ unsigned long get_wchan(struct task_stru } return 0; } - -EXPORT_SYMBOL(get_wchan); --- a/arch/nios2/include/asm/processor.h +++ b/arch/nios2/include/asm/processor.h @@ -69,7 +69,7 @@ static inline void release_thread(struct { } -extern unsigned long get_wchan(struct task_struct *p); +extern unsigned long __get_wchan(struct task_struct *p); #define task_pt_regs(p) \ ((struct pt_regs *)(THREAD_SIZE + task_stack_page(p)) - 1) --- a/arch/nios2/kernel/process.c +++ b/arch/nios2/kernel/process.c @@ -217,15 +217,12 @@ void dump(struct pt_regs *fp) pr_emerg("\n\n"); } -unsigned long get_wchan(struct task_struct *p) +unsigned long __get_wchan(struct task_struct *p) { unsigned long fp, pc; unsigned long stack_page; int count = 0; - if (!p || p == current || task_is_running(p)) - return 0; - stack_page = (unsigned long)p; fp = ((struct switch_stack *)p->thread.ksp)->fp; /* ;dgt2 */ do { --- a/arch/openrisc/include/asm/processor.h +++ b/arch/openrisc/include/asm/processor.h @@ -73,7 +73,7 @@ struct thread_struct { void start_thread(struct pt_regs *regs, unsigned long nip, unsigned long sp); void release_thread(struct task_struct *); -unsigned long get_wchan(struct task_struct *p); +unsigned long __get_wchan(struct task_struct *p); #define cpu_relax() barrier() --- a/arch/openrisc/kernel/process.c +++ b/arch/openrisc/kernel/process.c @@ -263,7 +263,7 @@ void dump_elf_thread(elf_greg_t *dest, s dest[35] = 0; } -unsigned long get_wchan(struct task_struct *p) +unsigned long __get_wchan(struct task_struct *p) { /* TODO */ --- a/arch/parisc/include/asm/processor.h +++ b/arch/parisc/include/asm/processor.h @@ -273,7 +273,7 @@ struct mm_struct; /* Free all resources held by a thread. */ extern void release_thread(struct task_struct *); -extern unsigned long get_wchan(struct task_struct *p); +extern unsigned long __get_wchan(struct task_struct *p); #define KSTK_EIP(tsk) ((tsk)->thread.regs.iaoq[0]) #define KSTK_ESP(tsk) ((tsk)->thread.regs.gr[30]) --- a/arch/parisc/kernel/process.c +++ b/arch/parisc/kernel/process.c @@ -240,15 +240,12 @@ copy_thread(unsigned long clone_flags, u } unsigned long -get_wchan(struct task_struct *p) +__get_wchan(struct task_struct *p) { struct unwind_frame_info info; unsigned long ip; int count = 0; - if (!p || p == current || task_is_running(p)) - return 0; - /* * These bracket the sleeping functions.. */ --- a/arch/powerpc/include/asm/processor.h +++ b/arch/powerpc/include/asm/processor.h @@ -300,7 +300,7 @@ struct thread_struct { #define task_pt_regs(tsk) ((tsk)->thread.regs) -unsigned long get_wchan(struct task_struct *p); +unsigned long __get_wchan(struct task_struct *p); #define KSTK_EIP(tsk) ((tsk)->thread.regs? (tsk)->thread.regs->nip: 0) #define KSTK_ESP(tsk) ((tsk)->thread.regs? (tsk)->thread.regs->gpr[1]: 0) --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -2111,14 +2111,11 @@ int validate_sp(unsigned long sp, struct EXPORT_SYMBOL(validate_sp); -static unsigned long __get_wchan(struct task_struct *p) +static unsigned long ___get_wchan(struct task_struct *p) { unsigned long ip, sp; int count = 0; - if (!p || p == current || task_is_running(p)) - return 0; - sp = p->thread.ksp; if (!validate_sp(sp, p, STACK_FRAME_OVERHEAD)) return 0; @@ -2137,14 +2134,14 @@ static unsigned long __get_wchan(struct return 0; } -unsigned long get_wchan(struct task_struct *p) +unsigned long __get_wchan(struct task_struct *p) { unsigned long ret; if (!try_get_task_stack(p)) return 0; - ret = __get_wchan(p); + ret = ___get_wchan(p); put_task_stack(p); --- a/arch/riscv/include/asm/processor.h +++ b/arch/riscv/include/asm/processor.h @@ -66,7 +66,7 @@ static inline void release_thread(struct { } -extern unsigned long get_wchan(struct task_struct *p); +extern unsigned long __get_wchan(struct task_struct *p); static inline void wait_for_interrupt(void) --- a/arch/riscv/kernel/stacktrace.c +++ b/arch/riscv/kernel/stacktrace.c @@ -128,16 +128,14 @@ static bool save_wchan(void *arg, unsign return true; } -unsigned long get_wchan(struct task_struct *task) +unsigned long __get_wchan(struct task_struct *task) { unsigned long pc = 0; - if (likely(task && task != current && !task_is_running(task))) { - if (!try_get_task_stack(task)) - return 0; - walk_stackframe(task, NULL, save_wchan, &pc); - put_task_stack(task); - } + if (!try_get_task_stack(task)) + return 0; + walk_stackframe(task, NULL, save_wchan, &pc); + put_task_stack(task); return pc; } --- a/arch/s390/include/asm/processor.h +++ b/arch/s390/include/asm/processor.h @@ -192,7 +192,7 @@ static inline void release_thread(struct void guarded_storage_release(struct task_struct *tsk); void gs_load_bc_cb(struct pt_regs *regs); -unsigned long get_wchan(struct task_struct *p); +unsigned long __get_wchan(struct task_struct *p); #define task_pt_regs(tsk) ((struct pt_regs *) \ (task_stack_page(tsk) + THREAD_SIZE) - 1) #define KSTK_EIP(tsk) (task_pt_regs(tsk)->psw.addr) --- a/arch/s390/kernel/process.c +++ b/arch/s390/kernel/process.c @@ -181,12 +181,12 @@ void execve_tail(void) asm volatile("sfpc %0" : : "d" (0)); } -unsigned long get_wchan(struct task_struct *p) +unsigned long __get_wchan(struct task_struct *p) { struct unwind_state state; unsigned long ip = 0; - if (!p || p == current || task_is_running(p) || !task_stack_page(p)) + if (!task_stack_page(p)) return 0; if (!try_get_task_stack(p)) --- a/arch/sh/include/asm/processor_32.h +++ b/arch/sh/include/asm/processor_32.h @@ -180,7 +180,7 @@ static inline void show_code(struct pt_r } #endif -extern unsigned long get_wchan(struct task_struct *p); +extern unsigned long __get_wchan(struct task_struct *p); #define KSTK_EIP(tsk) (task_pt_regs(tsk)->pc) #define KSTK_ESP(tsk) (task_pt_regs(tsk)->regs[15]) --- a/arch/sh/kernel/process_32.c +++ b/arch/sh/kernel/process_32.c @@ -182,13 +182,10 @@ __switch_to(struct task_struct *prev, st return prev; } -unsigned long get_wchan(struct task_struct *p) +unsigned long __get_wchan(struct task_struct *p) { unsigned long pc; - if (!p || p == current || task_is_running(p)) - return 0; - /* * The same comment as on the Alpha applies here, too ... */ --- a/arch/sparc/include/asm/processor_32.h +++ b/arch/sparc/include/asm/processor_32.h @@ -89,7 +89,7 @@ static inline void start_thread(struct p /* Free all resources held by a thread. */ #define release_thread(tsk) do { } while(0) -unsigned long get_wchan(struct task_struct *); +unsigned long __get_wchan(struct task_struct *); #define task_pt_regs(tsk) ((tsk)->thread.kregs) #define KSTK_EIP(tsk) ((tsk)->thread.kregs->pc) --- a/arch/sparc/include/asm/processor_64.h +++ b/arch/sparc/include/asm/processor_64.h @@ -183,7 +183,7 @@ do { \ /* Free all resources held by a thread. */ #define release_thread(tsk) do { } while (0) -unsigned long get_wchan(struct task_struct *task); +unsigned long __get_wchan(struct task_struct *task); #define task_pt_regs(tsk) (task_thread_info(tsk)->kregs) #define KSTK_EIP(tsk) (task_pt_regs(tsk)->tpc) --- a/arch/sparc/kernel/process_32.c +++ b/arch/sparc/kernel/process_32.c @@ -365,7 +365,7 @@ int copy_thread(unsigned long clone_flag return 0; } -unsigned long get_wchan(struct task_struct *task) +unsigned long __get_wchan(struct task_struct *task) { unsigned long pc, fp, bias = 0; unsigned long task_base = (unsigned long) task; @@ -373,9 +373,6 @@ unsigned long get_wchan(struct task_stru struct reg_window32 *rw; int count = 0; - if (!task || task == current || task_is_running(task)) - goto out; - fp = task_thread_info(task)->ksp + bias; do { /* Bogus frame pointer? */ --- a/arch/sparc/kernel/process_64.c +++ b/arch/sparc/kernel/process_64.c @@ -663,7 +663,7 @@ int arch_dup_task_struct(struct task_str return 0; } -unsigned long get_wchan(struct task_struct *task) +unsigned long __get_wchan(struct task_struct *task) { unsigned long pc, fp, bias = 0; struct thread_info *tp; @@ -671,9 +671,6 @@ unsigned long get_wchan(struct task_stru unsigned long ret = 0; int count = 0; - if (!task || task == current || task_is_running(task)) - goto out; - tp = task_thread_info(task); bias = STACK_BIAS; fp = task_thread_info(task)->ksp + bias; --- a/arch/um/include/asm/processor-generic.h +++ b/arch/um/include/asm/processor-generic.h @@ -106,6 +106,6 @@ extern struct cpuinfo_um boot_cpu_data; #define cache_line_size() (boot_cpu_data.cache_alignment) #define KSTK_REG(tsk, reg) get_thread_reg(reg, &tsk->thread.switch_buf) -extern unsigned long get_wchan(struct task_struct *p); +extern unsigned long __get_wchan(struct task_struct *p); #endif --- a/arch/um/kernel/process.c +++ b/arch/um/kernel/process.c @@ -364,14 +364,11 @@ unsigned long arch_align_stack(unsigned } #endif -unsigned long get_wchan(struct task_struct *p) +unsigned long __get_wchan(struct task_struct *p) { unsigned long stack_page, sp, ip; bool seen_sched = 0; - if ((p == NULL) || (p == current) || task_is_running(p)) - return 0; - stack_page = (unsigned long) task_stack_page(p); /* Bail if the process has no kernel stack for some reason */ if (stack_page == 0) --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -590,7 +590,7 @@ static inline void load_sp0(unsigned lon /* Free all resources held by a thread. */ extern void release_thread(struct task_struct *); -unsigned long get_wchan(struct task_struct *p); +unsigned long __get_wchan(struct task_struct *p); /* * Generic CPUID function --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -943,13 +943,10 @@ unsigned long arch_randomize_brk(struct * because the task might wake up and we might look at a stack * changing under us. */ -unsigned long get_wchan(struct task_struct *p) +unsigned long __get_wchan(struct task_struct *p) { unsigned long entry = 0; - if (p == current || task_is_running(p)) - return 0; - stack_trace_save_tsk(p, &entry, 1, 0); return entry; } --- a/arch/xtensa/include/asm/processor.h +++ b/arch/xtensa/include/asm/processor.h @@ -215,7 +215,7 @@ struct mm_struct; /* Free all resources held by a thread. */ #define release_thread(thread) do { } while(0) -extern unsigned long get_wchan(struct task_struct *p); +extern unsigned long __get_wchan(struct task_struct *p); #define KSTK_EIP(tsk) (task_pt_regs(tsk)->pc) #define KSTK_ESP(tsk) (task_pt_regs(tsk)->areg[1]) --- a/arch/xtensa/kernel/process.c +++ b/arch/xtensa/kernel/process.c @@ -298,15 +298,12 @@ int copy_thread(unsigned long clone_flag * These bracket the sleeping functions.. */ -unsigned long get_wchan(struct task_struct *p) +unsigned long __get_wchan(struct task_struct *p) { unsigned long sp, pc; unsigned long stack_page = (unsigned long) task_stack_page(p); int count = 0; - if (!p || p == current || task_is_running(p)) - return 0; - sp = p->thread.sp; pc = MAKE_PC_FROM_RA(p->thread.ra, p->thread.sp); --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2139,6 +2139,7 @@ static inline void set_task_cpu(struct t #endif /* CONFIG_SMP */ extern bool sched_task_on_rq(struct task_struct *p); +extern unsigned long get_wchan(struct task_struct *p); /* * In order to reduce various lock holder preemption latencies provide an --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1962,6 +1962,25 @@ bool sched_task_on_rq(struct task_struct return task_on_rq_queued(p); } +unsigned long get_wchan(struct task_struct *p) +{ + unsigned long ip = 0; + unsigned int state; + + if (!p || p == current) + return 0; + + /* Only get wchan if task is blocked and we can keep it that way. */ + raw_spin_lock_irq(&p->pi_lock); + state = READ_ONCE(p->__state); + smp_rmb(); /* see try_to_wake_up() */ + if (state != TASK_RUNNING && state != TASK_WAKING && !p->on_rq) + ip = __get_wchan(p); + raw_spin_unlock_irq(&p->pi_lock); + + return ip; +} + static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags) { if (!(flags & ENQUEUE_NOCLOCK))