| Message ID | 20211008111626.332092234@infradead.org (mailing list archive) |
|---|---|
| State | Mainlined |
| Headers | show |
| Series | wchan: Fix wchan support | expand |
On Fri, Oct 8, 2021 at 1:20 PM Peter Zijlstra <peterz@infradead.org> wrote: > From: Kees Cook <keescook@chromium.org> > > 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 <peterz@infradead.org> > Signed-off-by: Kees Cook <keescook@chromium.org> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > arch/m68k/include/asm/processor.h | 2 +- > arch/m68k/kernel/process.c | 4 +--- Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Gr{oetje,eeting}s, Geert
On Fri, Oct 08, 2021 at 01:15:32PM +0200, Peter Zijlstra wrote: > From: Kees Cook <keescook@chromium.org> > > 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 <peterz@infradead.org> > Signed-off-by: Kees Cook <keescook@chromium.org> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> FWIW, this seems to wpork on arm64: Tested-by: Mark Rutland <mark.rutland@arm.com> [arm64] Mark. > --- > 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)) > >
On Fri, Oct 08, 2021 at 01:15:32PM +0200, Peter Zijlstra wrote: > From: Kees Cook <keescook@chromium.org> > > 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 <peterz@infradead.org> > Signed-off-by: Kees Cook <keescook@chromium.org> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> [arm] I will eventually get around to test this once I've caught up.
--- 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))