| Message ID | 20210929220218.691419-3-keescook@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | wchan: Fix ORC support and leaky fallback | expand |
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 <keescook@chromium.org> Date: Wed, 29 Sep 2021 15:02:14 -0700 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> [peterz: __get_wchan] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- 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 Thu, Sep 30, 2021 at 10:27:07AM +0200, Peter Zijlstra wrote: > 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? > On top of which we can do.. --- Subject: arch: __get_wchan || STACKTRACE_SUPPORT From: Peter Zijlstra <peterz@infradead.org> Date: Thu Sep 30 10:08:13 CEST 2021 It's trivial to implement __get_wchan() with CONFIG_STACKTRACE Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- arch/arc/include/asm/processor.h | 2 - arch/arc/kernel/stacktrace.c | 17 -------------- arch/arm/include/asm/processor.h | 2 - arch/arm/kernel/process.c | 22 ------------------- arch/arm64/include/asm/processor.h | 2 - arch/arm64/kernel/process.c | 26 ---------------------- arch/csky/include/asm/processor.h | 2 - arch/csky/kernel/stacktrace.c | 18 --------------- arch/microblaze/include/asm/processor.h | 2 - arch/microblaze/kernel/process.c | 6 ----- arch/mips/include/asm/processor.h | 2 - arch/mips/kernel/process.c | 27 ----------------------- arch/nds32/include/asm/processor.h | 2 - arch/nds32/kernel/process.c | 23 ------------------- arch/openrisc/include/asm/processor.h | 1 arch/openrisc/kernel/process.c | 6 ----- arch/parisc/include/asm/processor.h | 2 - arch/parisc/kernel/process.c | 24 -------------------- arch/powerpc/include/asm/processor.h | 2 - arch/powerpc/kernel/process.c | 37 -------------------------------- arch/riscv/include/asm/processor.h | 3 -- arch/riscv/kernel/stacktrace.c | 21 ------------------ arch/s390/include/asm/processor.h | 1 arch/s390/kernel/process.c | 29 ------------------------- arch/sh/include/asm/processor_32.h | 2 - arch/sh/kernel/process_32.c | 19 ---------------- arch/sparc/include/asm/processor_64.h | 2 - arch/sparc/kernel/process_64.c | 28 ------------------------ arch/um/include/asm/processor-generic.h | 1 arch/um/kernel/process.c | 32 --------------------------- arch/x86/include/asm/processor.h | 2 - arch/x86/kernel/process.c | 14 ------------ arch/xtensa/include/asm/processor.h | 2 - arch/xtensa/kernel/process.c | 29 ------------------------- kernel/sched/core.c | 15 ++++++++++++ lib/Kconfig.debug | 7 ------ 36 files changed, 16 insertions(+), 416 deletions(-) --- a/arch/arc/include/asm/processor.h +++ b/arch/arc/include/asm/processor.h @@ -70,8 +70,6 @@ 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); - #endif /* !__ASSEMBLY__ */ /* --- a/arch/arc/kernel/stacktrace.c +++ b/arch/arc/kernel/stacktrace.c @@ -217,14 +217,6 @@ static int __collect_all_but_sched(unsig #endif -static int __get_first_nonsched(unsigned int address, void *unused) -{ - if (in_sched_functions(address)) - return 0; - - return -1; -} - /*------------------------------------------------------------------------- * APIs expected by various kernel sub-systems *------------------------------------------------------------------------- @@ -244,15 +236,6 @@ void show_stack(struct task_struct *tsk, show_stacktrace(tsk, NULL, loglvl); } -/* Another API expected by schedular, shows up in "ps" as Wait Channel - * 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) -{ - return arc_unwind_core(tsk, NULL, __get_first_nonsched, NULL); -} - #ifdef CONFIG_STACKTRACE /* --- a/arch/arm/include/asm/processor.h +++ b/arch/arm/include/asm/processor.h @@ -84,8 +84,6 @@ 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); - #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 @@ -276,28 +276,6 @@ int copy_thread(unsigned long clone_flag return 0; } -unsigned long __get_wchan(struct task_struct *p) -{ - struct stackframe frame; - unsigned long stack_page; - int count = 0; - - frame.fp = thread_saved_fp(p); - frame.sp = thread_saved_sp(p); - frame.lr = 0; /* recovered from the stack */ - frame.pc = thread_saved_pc(p); - stack_page = (unsigned long)task_stack_page(p); - do { - if (frame.sp < stack_page || - frame.sp >= stack_page + THREAD_SIZE || - unwind_frame(&frame) < 0) - return 0; - if (!in_sched_functions(frame.pc)) - return frame.pc; - } while (count ++ < 16); - return 0; -} - #ifdef CONFIG_MMU #ifdef CONFIG_KUSER_HELPERS /* --- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -257,8 +257,6 @@ 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); - void update_sctlr_el1(u64 sctlr); /* Thread switching */ --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -528,32 +528,6 @@ __notrace_funcgraph struct task_struct * return last; } -unsigned long __get_wchan(struct task_struct *p) -{ - struct stackframe frame; - unsigned long stack_page, ret = 0; - int count = 0; - - stack_page = (unsigned long)try_get_task_stack(p); - if (!stack_page) - return 0; - - start_backtrace(&frame, thread_saved_fp(p), thread_saved_pc(p)); - - do { - if (unwind_frame(p, &frame)) - goto out; - if (!in_sched_functions(frame.pc)) { - ret = frame.pc; - goto out; - } - } while (count++ < 16); - -out: - put_task_stack(p); - return ret; -} - unsigned long arch_align_stack(unsigned long sp) { if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) --- a/arch/csky/include/asm/processor.h +++ b/arch/csky/include/asm/processor.h @@ -81,8 +81,6 @@ 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); - #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 @@ -101,24 +101,6 @@ void show_stack(struct task_struct *task walk_stackframe(task, NULL, print_trace_address, (void *)loglvl); } -static bool save_wchan(unsigned long pc, void *arg) -{ - if (!in_sched_functions(pc)) { - unsigned long *p = arg; - *p = pc; - return true; - } - return false; -} - -unsigned long __get_wchan(struct task_struct *task) -{ - unsigned long pc = 0; - - walk_stackframe(task, NULL, save_wchan, &pc); - return pc; -} - #ifdef CONFIG_STACKTRACE static bool __save_trace(unsigned long pc, void *arg, bool nosched) { --- a/arch/microblaze/include/asm/processor.h +++ b/arch/microblaze/include/asm/processor.h @@ -68,8 +68,6 @@ static inline void release_thread(struct { } -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 @@ -112,12 +112,6 @@ int copy_thread(unsigned long clone_flag return 0; } -unsigned long __get_wchan(struct task_struct *p) -{ -/* TBD (used by procfs) */ - return 0; -} - /* Set up a thread for executing a new program */ void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp) { --- a/arch/mips/include/asm/processor.h +++ b/arch/mips/include/asm/processor.h @@ -369,8 +369,6 @@ static inline void flush_thread(void) { } -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)) #define task_pt_regs(tsk) ((struct pt_regs *)__KSTK_TOS(tsk)) --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -651,33 +651,6 @@ unsigned long unwind_stack(struct task_s } #endif -/* - * __get_wchan - a maintenance nightmare^W^Wpain in the ass ... - */ -unsigned long __get_wchan(struct task_struct *task) -{ - unsigned long pc = 0; -#ifdef CONFIG_KALLSYMS - unsigned long sp; - unsigned long ra = 0; -#endif - - if (!task_stack_page(task)) - goto out; - - pc = thread_saved_pc(task); - -#ifdef CONFIG_KALLSYMS - sp = task->thread.reg29 + schedule_mfi.frame_size; - - while (in_sched_functions(pc)) - pc = unwind_stack(task, &sp, pc, &ra); -#endif - -out: - return pc; -} - unsigned long mips_stack_top(void) { unsigned long top = TASK_SIZE & PAGE_MASK; --- a/arch/nds32/include/asm/processor.h +++ b/arch/nds32/include/asm/processor.h @@ -83,8 +83,6 @@ 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); - #define cpu_relax() barrier() #define task_pt_regs(task) \ --- a/arch/nds32/kernel/process.c +++ b/arch/nds32/kernel/process.c @@ -232,26 +232,3 @@ int dump_fpu(struct pt_regs *regs, elf_f } EXPORT_SYMBOL(dump_fpu); - -unsigned long __get_wchan(struct task_struct *p) -{ - unsigned long fp, lr; - unsigned long stack_start, stack_end; - int count = 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; - - fp = thread_saved_fp(p); - do { - if (fp < stack_start || fp > stack_end) - return 0; - lr = ((unsigned long *)fp)[0]; - if (!in_sched_functions(lr)) - return lr; - fp = *(unsigned long *)(fp + 4); - } while (count++ < 16); - } - return 0; -} --- a/arch/openrisc/include/asm/processor.h +++ b/arch/openrisc/include/asm/processor.h @@ -73,7 +73,6 @@ 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); #define cpu_relax() barrier() --- a/arch/openrisc/kernel/process.c +++ b/arch/openrisc/kernel/process.c @@ -263,9 +263,3 @@ void dump_elf_thread(elf_greg_t *dest, s dest[35] = 0; } -unsigned long __get_wchan(struct task_struct *p) -{ - /* TODO */ - - return 0; -} --- a/arch/parisc/include/asm/processor.h +++ b/arch/parisc/include/asm/processor.h @@ -273,8 +273,6 @@ 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); - #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 @@ -239,30 +239,6 @@ copy_thread(unsigned long clone_flags, u return 0; } -unsigned long -__get_wchan(struct task_struct *p) -{ - struct unwind_frame_info info; - unsigned long ip; - int count = 0; - - /* - * These bracket the sleeping functions.. - */ - - unwind_frame_init_from_blocked_task(&info, p); - do { - if (unwind_once(&info) < 0) - return 0; - if (task_is_running(p)) - return 0; - ip = info.ip; - if (!in_sched_functions(ip)) - return ip; - } while (count++ < MAX_UNWIND_ENTRIES); - return 0; -} - #ifdef CONFIG_64BIT void *dereference_function_descriptor(void *ptr) { --- a/arch/powerpc/include/asm/processor.h +++ b/arch/powerpc/include/asm/processor.h @@ -300,8 +300,6 @@ struct thread_struct { #define task_pt_regs(tsk) ((tsk)->thread.regs) -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 @@ -2111,43 +2111,6 @@ int validate_sp(unsigned long sp, struct EXPORT_SYMBOL(validate_sp); -static unsigned long ___get_wchan(struct task_struct *p) -{ - unsigned long ip, sp; - int count = 0; - - sp = p->thread.ksp; - if (!validate_sp(sp, p, STACK_FRAME_OVERHEAD)) - return 0; - - do { - sp = *(unsigned long *)sp; - if (!validate_sp(sp, p, STACK_FRAME_OVERHEAD) || - task_is_running(p)) - return 0; - if (count > 0) { - ip = ((unsigned long *)sp)[STACK_FRAME_LR_SAVE]; - if (!in_sched_functions(ip)) - return ip; - } - } while (count++ < 16); - return 0; -} - -unsigned long __get_wchan(struct task_struct *p) -{ - unsigned long ret; - - if (!try_get_task_stack(p)) - return 0; - - ret = ___get_wchan(p); - - put_task_stack(p); - - return ret; -} - static int kstack_depth_to_print = CONFIG_PRINT_STACK_DEPTH; void __no_sanitize_address show_stack(struct task_struct *tsk, --- a/arch/riscv/include/asm/processor.h +++ b/arch/riscv/include/asm/processor.h @@ -66,9 +66,6 @@ static inline void release_thread(struct { } -extern unsigned long __get_wchan(struct task_struct *p); - - static inline void wait_for_interrupt(void) { __asm__ __volatile__ ("wfi"); --- a/arch/riscv/kernel/stacktrace.c +++ b/arch/riscv/kernel/stacktrace.c @@ -118,27 +118,6 @@ void show_stack(struct task_struct *task dump_backtrace(NULL, task, loglvl); } -static bool save_wchan(void *arg, unsigned long pc) -{ - if (!in_sched_functions(pc)) { - unsigned long *p = arg; - *p = pc; - return false; - } - return true; -} - -unsigned long __get_wchan(struct task_struct *task) -{ - unsigned long pc = 0; - - if (!try_get_task_stack(task)) - return 0; - walk_stackframe(task, NULL, save_wchan, &pc); - put_task_stack(task); - return pc; -} - #ifdef CONFIG_STACKTRACE noinline void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie, --- a/arch/s390/include/asm/processor.h +++ b/arch/s390/include/asm/processor.h @@ -192,7 +192,6 @@ 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); #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 @@ -181,35 +181,6 @@ void execve_tail(void) asm volatile("sfpc %0" : : "d" (0)); } -unsigned long __get_wchan(struct task_struct *p) -{ - struct unwind_state state; - unsigned long ip = 0; - - if (!task_stack_page(p)) - return 0; - - if (!try_get_task_stack(p)) - return 0; - - unwind_for_each_frame(&state, p, NULL, 0) { - if (state.stack_info.type != STACK_TYPE_TASK) { - ip = 0; - break; - } - - ip = unwind_get_return_address(&state); - if (!ip) - break; - - if (!in_sched_functions(ip)) - break; - } - - put_task_stack(p); - return ip; -} - unsigned long arch_align_stack(unsigned long sp) { if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) --- a/arch/sh/include/asm/processor_32.h +++ b/arch/sh/include/asm/processor_32.h @@ -180,8 +180,6 @@ static inline void show_code(struct pt_r } #endif -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 @@ -181,22 +181,3 @@ __switch_to(struct task_struct *prev, st return prev; } - -unsigned long __get_wchan(struct task_struct *p) -{ - unsigned long pc; - - /* - * The same comment as on the Alpha applies here, too ... - */ - pc = thread_saved_pc(p); - -#ifdef CONFIG_FRAME_POINTER - if (in_sched_functions(pc)) { - unsigned long schedule_frame = (unsigned long)p->thread.sp; - return ((unsigned long *)schedule_frame)[21]; - } -#endif - - return pc; -} --- a/arch/sparc/include/asm/processor_64.h +++ b/arch/sparc/include/asm/processor_64.h @@ -183,8 +183,6 @@ do { \ /* Free all resources held by a thread. */ #define release_thread(tsk) do { } while (0) -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) #define KSTK_ESP(tsk) (task_pt_regs(tsk)->u_regs[UREG_FP]) --- a/arch/sparc/kernel/process_64.c +++ b/arch/sparc/kernel/process_64.c @@ -662,31 +662,3 @@ int arch_dup_task_struct(struct task_str *dst = *src; return 0; } - -unsigned long __get_wchan(struct task_struct *task) -{ - unsigned long pc, fp, bias = 0; - struct thread_info *tp; - struct reg_window *rw; - unsigned long ret = 0; - int count = 0; - - tp = task_thread_info(task); - bias = STACK_BIAS; - fp = task_thread_info(task)->ksp + bias; - - do { - if (!kstack_valid(tp, fp)) - break; - rw = (struct reg_window *) fp; - pc = rw->ins[7]; - if (!in_sched_functions(pc)) { - ret = pc; - goto out; - } - fp = rw->ins[6] + bias; - } while (++count < 16); - -out: - return ret; -} --- a/arch/um/include/asm/processor-generic.h +++ b/arch/um/include/asm/processor-generic.h @@ -106,6 +106,5 @@ 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); #endif --- a/arch/um/kernel/process.c +++ b/arch/um/kernel/process.c @@ -364,38 +364,6 @@ unsigned long arch_align_stack(unsigned } #endif -unsigned long __get_wchan(struct task_struct *p) -{ - unsigned long stack_page, sp, ip; - bool seen_sched = 0; - - stack_page = (unsigned long) task_stack_page(p); - /* Bail if the process has no kernel stack for some reason */ - if (stack_page == 0) - return 0; - - sp = p->thread.switch_buf->JB_SP; - /* - * Bail if the stack pointer is below the bottom of the kernel - * stack for some reason - */ - if (sp < stack_page) - return 0; - - while (sp < stack_page + THREAD_SIZE) { - ip = *((unsigned long *) sp); - if (in_sched_functions(ip)) - /* Ignore everything until we're above the scheduler */ - seen_sched = 1; - else if (kernel_text_address(ip) && seen_sched) - return ip; - - sp += sizeof(unsigned long); - } - - return 0; -} - int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu) { int cpu = current_thread_info()->cpu; --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -590,8 +590,6 @@ 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); - /* * Generic CPUID function * clear %ecx since some cpus (Cyrix MII) do not set or clear %ecx --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -937,20 +937,6 @@ unsigned long arch_randomize_brk(struct return randomize_page(mm->brk, 0x02000000); } -/* - * Called from fs/proc with a reference on @p to find the function - * which called into schedule(). This needs to be done carefully - * 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 entry = 0; - - stack_trace_save_tsk(p, &entry, 1, 0); - return entry; -} - long do_arch_prctl_common(struct task_struct *task, int option, unsigned long cpuid_enabled) { --- a/arch/xtensa/include/asm/processor.h +++ b/arch/xtensa/include/asm/processor.h @@ -215,8 +215,6 @@ 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); - #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 @@ -293,32 +293,3 @@ int copy_thread(unsigned long clone_flag return 0; } - -/* - * These bracket the sleeping functions.. - */ - -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; - - sp = p->thread.sp; - pc = MAKE_PC_FROM_RA(p->thread.ra, p->thread.sp); - - do { - if (sp < stack_page + sizeof(struct task_struct) || - sp >= (stack_page + THREAD_SIZE) || - pc == 0) - return 0; - if (!in_sched_functions(pc)) - return pc; - - /* Stack layout: sp-4: ra, sp-3: sp' */ - - pc = MAKE_PC_FROM_RA(SPILL_SLOT(sp, 0), sp); - sp = SPILL_SLOT(sp, 1); - } while (count++ < 16); - return 0; -} --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1962,6 +1962,21 @@ bool sched_task_on_rq(struct task_struct return task_on_rq_queued(p); } +#ifdef CONFIG_STACKTRACE +static unsigned long __get_wchan(struct task_struct *p) +{ + unsigned long entry = 0; + + stack_trace_save_tsk(p, &entry, 1, 0); + + return entry; +} +#endif + +/* + * Called from fs/proc with a reference on @p to find the function + * which called into schedule(). + */ unsigned long get_wchan(struct task_struct *p) { unsigned long ip = 0; --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1531,13 +1531,8 @@ config DEBUG_IRQFLAGS are enabled. config STACKTRACE - bool "Stack backtrace support" + def_bool y depends on STACKTRACE_SUPPORT - help - This option causes the kernel to create a /proc/pid/stack for - every process, showing its current stack trace. - It is also used by various kernel debugging features that require - stack trace generation. config WARN_ALL_UNSEEDED_RANDOM bool "Warn for all uses of unseeded randomness"
On Thu, Sep 30, 2021 at 10:28:37AM +0200, Peter Zijlstra wrote: > On Thu, Sep 30, 2021 at 10:27:07AM +0200, Peter Zijlstra wrote: > > 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? > > > On top of which we can do.. But that then leads to.. --- Subject: arch: Fix STACKTRACE_SUPPORT From: Peter Zijlstra <peterz@infradead.org> Date: Thu Sep 30 10:21:15 CEST 2021 A few archs got save_stack_trace_tsk() vs in_sched_functions() wrong. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- arch/csky/kernel/stacktrace.c | 7 ++++++- arch/mips/kernel/stacktrace.c | 27 ++++++++++++++++----------- arch/nds32/kernel/stacktrace.c | 20 +++++++++++--------- 3 files changed, 33 insertions(+), 21 deletions(-) --- a/arch/csky/kernel/stacktrace.c +++ b/arch/csky/kernel/stacktrace.c @@ -132,12 +132,17 @@ static bool save_trace(unsigned long pc, return __save_trace(pc, arg, false); } +static bool save_trace_nosched(unsigned long pc, void *arg) +{ + return __save_trace(pc, arg, true); +} + /* * Save stack-backtrace addresses into a stack_trace buffer. */ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) { - walk_stackframe(tsk, NULL, save_trace, trace); + walk_stackframe(tsk, NULL, save_trace_nosched, trace); } EXPORT_SYMBOL_GPL(save_stack_trace_tsk); --- a/arch/mips/kernel/stacktrace.c +++ b/arch/mips/kernel/stacktrace.c @@ -66,16 +66,7 @@ static void save_context_stack(struct st #endif } -/* - * Save stack-backtrace addresses into a stack_trace buffer. - */ -void save_stack_trace(struct stack_trace *trace) -{ - save_stack_trace_tsk(current, trace); -} -EXPORT_SYMBOL_GPL(save_stack_trace); - -void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) +void __save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace, bool savesched) { struct pt_regs dummyregs; struct pt_regs *regs = &dummyregs; @@ -88,6 +79,20 @@ void save_stack_trace_tsk(struct task_st regs->cp0_epc = tsk->thread.reg31; } else prepare_frametrace(regs); - save_context_stack(trace, tsk, regs, tsk == current); + save_context_stack(trace, tsk, regs, savesched); +} + +/* + * Save stack-backtrace addresses into a stack_trace buffer. + */ +void save_stack_trace(struct stack_trace *trace) +{ + __save_stack_trace_tsk(current, trace, true); +} +EXPORT_SYMBOL_GPL(save_stack_trace); + +void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) +{ + __save_stack_trace_tsk(tsk, trace, false); } EXPORT_SYMBOL_GPL(save_stack_trace_tsk); --- a/arch/nds32/kernel/stacktrace.c +++ b/arch/nds32/kernel/stacktrace.c @@ -6,13 +6,7 @@ #include <linux/stacktrace.h> #include <linux/ftrace.h> -void save_stack_trace(struct stack_trace *trace) -{ - save_stack_trace_tsk(current, trace); -} -EXPORT_SYMBOL_GPL(save_stack_trace); - -void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) +static void __save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace, bool savesched) { unsigned long *fpn; int skip = trace->skip; @@ -21,10 +15,8 @@ void save_stack_trace_tsk(struct task_st if (tsk == current) { __asm__ __volatile__("\tori\t%0, $fp, #0\n":"=r"(fpn)); - savesched = 1; } else { fpn = (unsigned long *)thread_saved_fp(tsk); - savesched = 0; } while (!kstack_end(fpn) && !((unsigned long)fpn & 0x3) @@ -50,4 +42,14 @@ void save_stack_trace_tsk(struct task_st fpn = (unsigned long *)fpp; } } +void save_stack_trace(struct stack_trace *trace) +{ + __save_stack_trace_tsk(current, trace, true); +} +EXPORT_SYMBOL_GPL(save_stack_trace); + +void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) +{ + __save_stack_trace_tsk(tsk, trace, false); +} EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
diff --git a/include/linux/sched.h b/include/linux/sched.h index 39039ce8ac4c..0c8185089e20 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2137,6 +2137,7 @@ static inline void set_task_cpu(struct task_struct *p, unsigned int cpu) #endif /* CONFIG_SMP */ extern bool sched_task_on_rq(struct task_struct *p); +extern unsigned long sched_task_get_wchan(struct task_struct *p); /* * In order to reduce various lock holder preemption latencies provide an diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 1bba4128a3e6..4a30455e1ff5 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1962,6 +1962,22 @@ bool sched_task_on_rq(struct task_struct *p) return task_on_rq_queued(p); } +unsigned long sched_task_get_wchan(struct task_struct *p) +{ + unsigned int state; + unsigned long ip = 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))
Having a stable wchan means the process must be blocked and for it to stay that way while performing stack unwinding. Cc: Ingo Molnar <mingo@redhat.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ben Segall <bsegall@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Daniel Bristot de Oliveira <bristot@redhat.com> Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Kees Cook <keescook@chromium.org> --- include/linux/sched.h | 1 + kernel/sched/core.c | 16 ++++++++++++++++ 2 files changed, 17 insertions(+)