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@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxx>
---
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"
