Commit 42a20f86 authored by Kees Cook's avatar Kees Cook Committed by Peter Zijlstra

sched: Add wrapper for get_wchan() to keep task blocked

Having a stable wchan means the process must be blocked and for it to
stay that way while performing stack unwinding.
Suggested-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> [arm]
Tested-by: Mark Rutland <mark.rutland@arm.com> [arm64]
Link: https://lkml.kernel.org/r/20211008111626.332092234@infradead.org
parent bc9bbb81
......@@ -42,7 +42,7 @@ extern void start_thread(struct pt_regs *, unsigned long, unsigned long);
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)
......
......@@ -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
......
......@@ -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__ */
......
......@@ -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, unsigned long *sp, const char *loglvl)
* 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);
}
......
......@@ -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)
......
......@@ -276,13 +276,11 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start,
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);
......
......@@ -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);
......
......@@ -528,13 +528,11 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev,
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)
......
......@@ -81,7 +81,7 @@ static inline void release_thread(struct task_struct *dead_task)
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)
......
......@@ -111,11 +111,10 @@ static bool save_wchan(unsigned long pc, void *arg)
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);
return pc;
}
......
......@@ -105,7 +105,7 @@ static inline void release_thread(struct task_struct *dead_task)
{
}
unsigned long get_wchan(struct task_struct *p);
unsigned long __get_wchan(struct task_struct *p);
#define KSTK_EIP(tsk) \
({ \
......
......@@ -128,15 +128,12 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
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 {
......
......@@ -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. */
......
......@@ -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;
......
......@@ -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) \
......
......@@ -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
......
......@@ -150,7 +150,7 @@ static inline void release_thread(struct task_struct *dead_task)
{
}
unsigned long get_wchan(struct task_struct *p);
unsigned long __get_wchan(struct task_struct *p);
#define KSTK_EIP(tsk) \
({ \
......
......@@ -263,13 +263,11 @@ int dump_fpu (struct pt_regs *regs, struct user_m68kfp_struct *fpu)
}
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;
......
......@@ -68,7 +68,7 @@ static inline void release_thread(struct task_struct *dead_task)
{
}
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
......
......@@ -112,7 +112,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp, unsigned long arg,
return 0;
}
unsigned long get_wchan(struct task_struct *p)
unsigned long __get_wchan(struct task_struct *p)
{
/* TBD (used by procfs) */
return 0;
......
......@@ -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))
......
......@@ -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_struct *task, unsigned long *sp,
#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_struct *task)
unsigned long ra = 0;
#endif
if (!task || task == current || task_is_running(task))
goto out;
if (!task_stack_page(task))
goto out;
......
......@@ -83,7 +83,7 @@ extern struct task_struct *last_task_used_math;
/* 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()
......
......@@ -233,15 +233,12 @@ int dump_fpu(struct pt_regs *regs, elf_fpregset_t * fpu)
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_struct *p)
}
return 0;
}
EXPORT_SYMBOL(get_wchan);
......@@ -69,7 +69,7 @@ static inline void release_thread(struct task_struct *dead_task)
{
}
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)
......
......@@ -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 {
......
......@@ -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()
......
......@@ -263,7 +263,7 @@ void dump_elf_thread(elf_greg_t *dest, struct pt_regs* regs)
dest[35] = 0;
}
unsigned long get_wchan(struct task_struct *p)
unsigned long __get_wchan(struct task_struct *p)
{
/* TODO */
......
......@@ -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])
......
......@@ -240,15 +240,12 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
}
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..
*/
......
......@@ -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)
......
......@@ -2111,14 +2111,11 @@ int validate_sp(unsigned long sp, struct task_struct *p,
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 task_struct *p)
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);
......
......@@ -66,7 +66,7 @@ static inline void release_thread(struct task_struct *dead_task)
{
}
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)
......
......@@ -128,16 +128,14 @@ static bool save_wchan(void *arg, unsigned long pc)
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);
}
return pc;
}
......
......@@ -192,7 +192,7 @@ static inline void release_thread(struct task_struct *tsk) { }
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)
......
......@@ -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))
......
......@@ -180,7 +180,7 @@ static inline void show_code(struct pt_regs *regs)
}
#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])
......
......@@ -182,13 +182,10 @@ __switch_to(struct task_struct *prev, struct task_struct *next)
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 ...
*/
......
......@@ -89,7 +89,7 @@ static inline void start_thread(struct pt_regs * regs, unsigned long pc,
/* 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)
......
......@@ -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)
......
......@@ -365,7 +365,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg,
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_struct *task)
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? */
......
......@@ -663,7 +663,7 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
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_struct *task)
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;
......
......@@ -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
......@@ -364,14 +364,11 @@ unsigned long arch_align_stack(unsigned long sp)
}
#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)
......
......@@ -589,7 +589,7 @@ static inline void load_sp0(unsigned long sp0)
/* 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
......
......@@ -942,13 +942,10 @@ unsigned long arch_randomize_brk(struct mm_struct *mm)
* 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;
}
......
......@@ -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])
......
......@@ -298,15 +298,12 @@ int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn,
* 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);
......
......@@ -2139,6 +2139,7 @@ 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 get_wchan(struct task_struct *p);
/*
* In order to reduce various lock holder preemption latencies provide an
......
......@@ -1966,6 +1966,25 @@ bool sched_task_on_rq(struct task_struct *p)
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))
......
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