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linux/linux-5.4.31/arch/sparc/kernel/process_64.c

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// SPDX-License-Identifier: GPL-2.0
/* arch/sparc64/kernel/process.c
*
* Copyright (C) 1995, 1996, 2008 David S. Miller (davem@davemloft.net)
* Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be)
* Copyright (C) 1997, 1998 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
*/
/*
* This file handles the architecture-dependent parts of process handling..
*/
#include <stdarg.h>
#include <linux/errno.h>
#include <linux/export.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/sched/task.h>
#include <linux/sched/task_stack.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/smp.h>
#include <linux/stddef.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/delay.h>
#include <linux/compat.h>
#include <linux/tick.h>
#include <linux/init.h>
#include <linux/cpu.h>
#include <linux/perf_event.h>
#include <linux/elfcore.h>
#include <linux/sysrq.h>
#include <linux/nmi.h>
#include <linux/context_tracking.h>
#include <linux/signal.h>
#include <linux/uaccess.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/pstate.h>
#include <asm/elf.h>
#include <asm/fpumacro.h>
#include <asm/head.h>
#include <asm/cpudata.h>
#include <asm/mmu_context.h>
#include <asm/unistd.h>
#include <asm/hypervisor.h>
#include <asm/syscalls.h>
#include <asm/irq_regs.h>
#include <asm/smp.h>
#include <asm/pcr.h>
#include "kstack.h"
/* Idle loop support on sparc64. */
void arch_cpu_idle(void)
{
if (tlb_type != hypervisor) {
touch_nmi_watchdog();
local_irq_enable();
} else {
unsigned long pstate;
local_irq_enable();
/* The sun4v sleeping code requires that we have PSTATE.IE cleared over
* the cpu sleep hypervisor call.
*/
__asm__ __volatile__(
"rdpr %%pstate, %0\n\t"
"andn %0, %1, %0\n\t"
"wrpr %0, %%g0, %%pstate"
: "=&r" (pstate)
: "i" (PSTATE_IE));
if (!need_resched() && !cpu_is_offline(smp_processor_id())) {
sun4v_cpu_yield();
/* If resumed by cpu_poke then we need to explicitly
* call scheduler_ipi().
*/
scheduler_poke();
}
/* Re-enable interrupts. */
__asm__ __volatile__(
"rdpr %%pstate, %0\n\t"
"or %0, %1, %0\n\t"
"wrpr %0, %%g0, %%pstate"
: "=&r" (pstate)
: "i" (PSTATE_IE));
}
}
#ifdef CONFIG_HOTPLUG_CPU
void arch_cpu_idle_dead(void)
{
sched_preempt_enable_no_resched();
cpu_play_dead();
}
#endif
#ifdef CONFIG_COMPAT
static void show_regwindow32(struct pt_regs *regs)
{
struct reg_window32 __user *rw;
struct reg_window32 r_w;
mm_segment_t old_fs;
__asm__ __volatile__ ("flushw");
rw = compat_ptr((unsigned int)regs->u_regs[14]);
old_fs = get_fs();
set_fs (USER_DS);
if (copy_from_user (&r_w, rw, sizeof(r_w))) {
set_fs (old_fs);
return;
}
set_fs (old_fs);
printk("l0: %08x l1: %08x l2: %08x l3: %08x "
"l4: %08x l5: %08x l6: %08x l7: %08x\n",
r_w.locals[0], r_w.locals[1], r_w.locals[2], r_w.locals[3],
r_w.locals[4], r_w.locals[5], r_w.locals[6], r_w.locals[7]);
printk("i0: %08x i1: %08x i2: %08x i3: %08x "
"i4: %08x i5: %08x i6: %08x i7: %08x\n",
r_w.ins[0], r_w.ins[1], r_w.ins[2], r_w.ins[3],
r_w.ins[4], r_w.ins[5], r_w.ins[6], r_w.ins[7]);
}
#else
#define show_regwindow32(regs) do { } while (0)
#endif
static void show_regwindow(struct pt_regs *regs)
{
struct reg_window __user *rw;
struct reg_window *rwk;
struct reg_window r_w;
mm_segment_t old_fs;
if ((regs->tstate & TSTATE_PRIV) || !(test_thread_flag(TIF_32BIT))) {
__asm__ __volatile__ ("flushw");
rw = (struct reg_window __user *)
(regs->u_regs[14] + STACK_BIAS);
rwk = (struct reg_window *)
(regs->u_regs[14] + STACK_BIAS);
if (!(regs->tstate & TSTATE_PRIV)) {
old_fs = get_fs();
set_fs (USER_DS);
if (copy_from_user (&r_w, rw, sizeof(r_w))) {
set_fs (old_fs);
return;
}
rwk = &r_w;
set_fs (old_fs);
}
} else {
show_regwindow32(regs);
return;
}
printk("l0: %016lx l1: %016lx l2: %016lx l3: %016lx\n",
rwk->locals[0], rwk->locals[1], rwk->locals[2], rwk->locals[3]);
printk("l4: %016lx l5: %016lx l6: %016lx l7: %016lx\n",
rwk->locals[4], rwk->locals[5], rwk->locals[6], rwk->locals[7]);
printk("i0: %016lx i1: %016lx i2: %016lx i3: %016lx\n",
rwk->ins[0], rwk->ins[1], rwk->ins[2], rwk->ins[3]);
printk("i4: %016lx i5: %016lx i6: %016lx i7: %016lx\n",
rwk->ins[4], rwk->ins[5], rwk->ins[6], rwk->ins[7]);
if (regs->tstate & TSTATE_PRIV)
printk("I7: <%pS>\n", (void *) rwk->ins[7]);
}
void show_regs(struct pt_regs *regs)
{
show_regs_print_info(KERN_DEFAULT);
printk("TSTATE: %016lx TPC: %016lx TNPC: %016lx Y: %08x %s\n", regs->tstate,
regs->tpc, regs->tnpc, regs->y, print_tainted());
printk("TPC: <%pS>\n", (void *) regs->tpc);
printk("g0: %016lx g1: %016lx g2: %016lx g3: %016lx\n",
regs->u_regs[0], regs->u_regs[1], regs->u_regs[2],
regs->u_regs[3]);
printk("g4: %016lx g5: %016lx g6: %016lx g7: %016lx\n",
regs->u_regs[4], regs->u_regs[5], regs->u_regs[6],
regs->u_regs[7]);
printk("o0: %016lx o1: %016lx o2: %016lx o3: %016lx\n",
regs->u_regs[8], regs->u_regs[9], regs->u_regs[10],
regs->u_regs[11]);
printk("o4: %016lx o5: %016lx sp: %016lx ret_pc: %016lx\n",
regs->u_regs[12], regs->u_regs[13], regs->u_regs[14],
regs->u_regs[15]);
printk("RPC: <%pS>\n", (void *) regs->u_regs[15]);
show_regwindow(regs);
show_stack(current, (unsigned long *) regs->u_regs[UREG_FP]);
}
union global_cpu_snapshot global_cpu_snapshot[NR_CPUS];
static DEFINE_SPINLOCK(global_cpu_snapshot_lock);
static void __global_reg_self(struct thread_info *tp, struct pt_regs *regs,
int this_cpu)
{
struct global_reg_snapshot *rp;
flushw_all();
rp = &global_cpu_snapshot[this_cpu].reg;
rp->tstate = regs->tstate;
rp->tpc = regs->tpc;
rp->tnpc = regs->tnpc;
rp->o7 = regs->u_regs[UREG_I7];
if (regs->tstate & TSTATE_PRIV) {
struct reg_window *rw;
rw = (struct reg_window *)
(regs->u_regs[UREG_FP] + STACK_BIAS);
if (kstack_valid(tp, (unsigned long) rw)) {
rp->i7 = rw->ins[7];
rw = (struct reg_window *)
(rw->ins[6] + STACK_BIAS);
if (kstack_valid(tp, (unsigned long) rw))
rp->rpc = rw->ins[7];
}
} else {
rp->i7 = 0;
rp->rpc = 0;
}
rp->thread = tp;
}
/* In order to avoid hangs we do not try to synchronize with the
* global register dump client cpus. The last store they make is to
* the thread pointer, so do a short poll waiting for that to become
* non-NULL.
*/
static void __global_reg_poll(struct global_reg_snapshot *gp)
{
int limit = 0;
while (!gp->thread && ++limit < 100) {
barrier();
udelay(1);
}
}
void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
{
struct thread_info *tp = current_thread_info();
struct pt_regs *regs = get_irq_regs();
unsigned long flags;
int this_cpu, cpu;
if (!regs)
regs = tp->kregs;
spin_lock_irqsave(&global_cpu_snapshot_lock, flags);
this_cpu = raw_smp_processor_id();
memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot));
if (cpumask_test_cpu(this_cpu, mask) && !exclude_self)
__global_reg_self(tp, regs, this_cpu);
smp_fetch_global_regs();
for_each_cpu(cpu, mask) {
struct global_reg_snapshot *gp;
if (exclude_self && cpu == this_cpu)
continue;
gp = &global_cpu_snapshot[cpu].reg;
__global_reg_poll(gp);
tp = gp->thread;
printk("%c CPU[%3d]: TSTATE[%016lx] TPC[%016lx] TNPC[%016lx] TASK[%s:%d]\n",
(cpu == this_cpu ? '*' : ' '), cpu,
gp->tstate, gp->tpc, gp->tnpc,
((tp && tp->task) ? tp->task->comm : "NULL"),
((tp && tp->task) ? tp->task->pid : -1));
if (gp->tstate & TSTATE_PRIV) {
printk(" TPC[%pS] O7[%pS] I7[%pS] RPC[%pS]\n",
(void *) gp->tpc,
(void *) gp->o7,
(void *) gp->i7,
(void *) gp->rpc);
} else {
printk(" TPC[%lx] O7[%lx] I7[%lx] RPC[%lx]\n",
gp->tpc, gp->o7, gp->i7, gp->rpc);
}
touch_nmi_watchdog();
}
memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot));
spin_unlock_irqrestore(&global_cpu_snapshot_lock, flags);
}
#ifdef CONFIG_MAGIC_SYSRQ
static void sysrq_handle_globreg(int key)
{
trigger_all_cpu_backtrace();
}
static struct sysrq_key_op sparc_globalreg_op = {
.handler = sysrq_handle_globreg,
.help_msg = "global-regs(y)",
.action_msg = "Show Global CPU Regs",
};
static void __global_pmu_self(int this_cpu)
{
struct global_pmu_snapshot *pp;
int i, num;
if (!pcr_ops)
return;
pp = &global_cpu_snapshot[this_cpu].pmu;
num = 1;
if (tlb_type == hypervisor &&
sun4v_chip_type >= SUN4V_CHIP_NIAGARA4)
num = 4;
for (i = 0; i < num; i++) {
pp->pcr[i] = pcr_ops->read_pcr(i);
pp->pic[i] = pcr_ops->read_pic(i);
}
}
static void __global_pmu_poll(struct global_pmu_snapshot *pp)
{
int limit = 0;
while (!pp->pcr[0] && ++limit < 100) {
barrier();
udelay(1);
}
}
static void pmu_snapshot_all_cpus(void)
{
unsigned long flags;
int this_cpu, cpu;
spin_lock_irqsave(&global_cpu_snapshot_lock, flags);
memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot));
this_cpu = raw_smp_processor_id();
__global_pmu_self(this_cpu);
smp_fetch_global_pmu();
for_each_online_cpu(cpu) {
struct global_pmu_snapshot *pp = &global_cpu_snapshot[cpu].pmu;
__global_pmu_poll(pp);
printk("%c CPU[%3d]: PCR[%08lx:%08lx:%08lx:%08lx] PIC[%08lx:%08lx:%08lx:%08lx]\n",
(cpu == this_cpu ? '*' : ' '), cpu,
pp->pcr[0], pp->pcr[1], pp->pcr[2], pp->pcr[3],
pp->pic[0], pp->pic[1], pp->pic[2], pp->pic[3]);
touch_nmi_watchdog();
}
memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot));
spin_unlock_irqrestore(&global_cpu_snapshot_lock, flags);
}
static void sysrq_handle_globpmu(int key)
{
pmu_snapshot_all_cpus();
}
static struct sysrq_key_op sparc_globalpmu_op = {
.handler = sysrq_handle_globpmu,
.help_msg = "global-pmu(x)",
.action_msg = "Show Global PMU Regs",
};
static int __init sparc_sysrq_init(void)
{
int ret = register_sysrq_key('y', &sparc_globalreg_op);
if (!ret)
ret = register_sysrq_key('x', &sparc_globalpmu_op);
return ret;
}
core_initcall(sparc_sysrq_init);
#endif
/* Free current thread data structures etc.. */
void exit_thread(struct task_struct *tsk)
{
struct thread_info *t = task_thread_info(tsk);
if (t->utraps) {
if (t->utraps[0] < 2)
kfree (t->utraps);
else
t->utraps[0]--;
}
}
void flush_thread(void)
{
struct thread_info *t = current_thread_info();
struct mm_struct *mm;
mm = t->task->mm;
if (mm)
tsb_context_switch(mm);
set_thread_wsaved(0);
/* Clear FPU register state. */
t->fpsaved[0] = 0;
}
/* It's a bit more tricky when 64-bit tasks are involved... */
static unsigned long clone_stackframe(unsigned long csp, unsigned long psp)
{
bool stack_64bit = test_thread_64bit_stack(psp);
unsigned long fp, distance, rval;
if (stack_64bit) {
csp += STACK_BIAS;
psp += STACK_BIAS;
__get_user(fp, &(((struct reg_window __user *)psp)->ins[6]));
fp += STACK_BIAS;
if (test_thread_flag(TIF_32BIT))
fp &= 0xffffffff;
} else
__get_user(fp, &(((struct reg_window32 __user *)psp)->ins[6]));
/* Now align the stack as this is mandatory in the Sparc ABI
* due to how register windows work. This hides the
* restriction from thread libraries etc.
*/
csp &= ~15UL;
distance = fp - psp;
rval = (csp - distance);
if (copy_in_user((void __user *) rval, (void __user *) psp, distance))
rval = 0;
else if (!stack_64bit) {
if (put_user(((u32)csp),
&(((struct reg_window32 __user *)rval)->ins[6])))
rval = 0;
} else {
if (put_user(((u64)csp - STACK_BIAS),
&(((struct reg_window __user *)rval)->ins[6])))
rval = 0;
else
rval = rval - STACK_BIAS;
}
return rval;
}
/* Standard stuff. */
static inline void shift_window_buffer(int first_win, int last_win,
struct thread_info *t)
{
int i;
for (i = first_win; i < last_win; i++) {
t->rwbuf_stkptrs[i] = t->rwbuf_stkptrs[i+1];
memcpy(&t->reg_window[i], &t->reg_window[i+1],
sizeof(struct reg_window));
}
}
void synchronize_user_stack(void)
{
struct thread_info *t = current_thread_info();
unsigned long window;
flush_user_windows();
if ((window = get_thread_wsaved()) != 0) {
window -= 1;
do {
struct reg_window *rwin = &t->reg_window[window];
int winsize = sizeof(struct reg_window);
unsigned long sp;
sp = t->rwbuf_stkptrs[window];
if (test_thread_64bit_stack(sp))
sp += STACK_BIAS;
else
winsize = sizeof(struct reg_window32);
if (!copy_to_user((char __user *)sp, rwin, winsize)) {
shift_window_buffer(window, get_thread_wsaved() - 1, t);
set_thread_wsaved(get_thread_wsaved() - 1);
}
} while (window--);
}
}
static void stack_unaligned(unsigned long sp)
{
force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) sp, 0);
}
static const char uwfault32[] = KERN_INFO \
"%s[%d]: bad register window fault: SP %08lx (orig_sp %08lx) TPC %08lx O7 %08lx\n";
static const char uwfault64[] = KERN_INFO \
"%s[%d]: bad register window fault: SP %016lx (orig_sp %016lx) TPC %08lx O7 %016lx\n";
void fault_in_user_windows(struct pt_regs *regs)
{
struct thread_info *t = current_thread_info();
unsigned long window;
flush_user_windows();
window = get_thread_wsaved();
if (likely(window != 0)) {
window -= 1;
do {
struct reg_window *rwin = &t->reg_window[window];
int winsize = sizeof(struct reg_window);
unsigned long sp, orig_sp;
orig_sp = sp = t->rwbuf_stkptrs[window];
if (test_thread_64bit_stack(sp))
sp += STACK_BIAS;
else
winsize = sizeof(struct reg_window32);
if (unlikely(sp & 0x7UL))
stack_unaligned(sp);
if (unlikely(copy_to_user((char __user *)sp,
rwin, winsize))) {
if (show_unhandled_signals)
printk_ratelimited(is_compat_task() ?
uwfault32 : uwfault64,
current->comm, current->pid,
sp, orig_sp,
regs->tpc,
regs->u_regs[UREG_I7]);
goto barf;
}
} while (window--);
}
set_thread_wsaved(0);
return;
barf:
set_thread_wsaved(window + 1);
force_sig(SIGSEGV);
}
asmlinkage long sparc_do_fork(unsigned long clone_flags,
unsigned long stack_start,
struct pt_regs *regs,
unsigned long stack_size)
{
int __user *parent_tid_ptr, *child_tid_ptr;
unsigned long orig_i1 = regs->u_regs[UREG_I1];
long ret;
#ifdef CONFIG_COMPAT
if (test_thread_flag(TIF_32BIT)) {
parent_tid_ptr = compat_ptr(regs->u_regs[UREG_I2]);
child_tid_ptr = compat_ptr(regs->u_regs[UREG_I4]);
} else
#endif
{
parent_tid_ptr = (int __user *) regs->u_regs[UREG_I2];
child_tid_ptr = (int __user *) regs->u_regs[UREG_I4];
}
ret = do_fork(clone_flags, stack_start, stack_size,
parent_tid_ptr, child_tid_ptr);
/* If we get an error and potentially restart the system
* call, we're screwed because copy_thread() clobbered
* the parent's %o1. So detect that case and restore it
* here.
*/
if ((unsigned long)ret >= -ERESTART_RESTARTBLOCK)
regs->u_regs[UREG_I1] = orig_i1;
return ret;
}
/* Copy a Sparc thread. The fork() return value conventions
* under SunOS are nothing short of bletcherous:
* Parent --> %o0 == childs pid, %o1 == 0
* Child --> %o0 == parents pid, %o1 == 1
*/
int copy_thread(unsigned long clone_flags, unsigned long sp,
unsigned long arg, struct task_struct *p)
{
struct thread_info *t = task_thread_info(p);
struct pt_regs *regs = current_pt_regs();
struct sparc_stackf *parent_sf;
unsigned long child_stack_sz;
char *child_trap_frame;
/* Calculate offset to stack_frame & pt_regs */
child_stack_sz = (STACKFRAME_SZ + TRACEREG_SZ);
child_trap_frame = (task_stack_page(p) +
(THREAD_SIZE - child_stack_sz));
t->new_child = 1;
t->ksp = ((unsigned long) child_trap_frame) - STACK_BIAS;
t->kregs = (struct pt_regs *) (child_trap_frame +
sizeof(struct sparc_stackf));
t->fpsaved[0] = 0;
if (unlikely(p->flags & PF_KTHREAD)) {
memset(child_trap_frame, 0, child_stack_sz);
__thread_flag_byte_ptr(t)[TI_FLAG_BYTE_CWP] =
(current_pt_regs()->tstate + 1) & TSTATE_CWP;
t->current_ds = ASI_P;
t->kregs->u_regs[UREG_G1] = sp; /* function */
t->kregs->u_regs[UREG_G2] = arg;
return 0;
}
parent_sf = ((struct sparc_stackf *) regs) - 1;
memcpy(child_trap_frame, parent_sf, child_stack_sz);
if (t->flags & _TIF_32BIT) {
sp &= 0x00000000ffffffffUL;
regs->u_regs[UREG_FP] &= 0x00000000ffffffffUL;
}
t->kregs->u_regs[UREG_FP] = sp;
__thread_flag_byte_ptr(t)[TI_FLAG_BYTE_CWP] =
(regs->tstate + 1) & TSTATE_CWP;
t->current_ds = ASI_AIUS;
if (sp != regs->u_regs[UREG_FP]) {
unsigned long csp;
csp = clone_stackframe(sp, regs->u_regs[UREG_FP]);
if (!csp)
return -EFAULT;
t->kregs->u_regs[UREG_FP] = csp;
}
if (t->utraps)
t->utraps[0]++;
/* Set the return value for the child. */
t->kregs->u_regs[UREG_I0] = current->pid;
t->kregs->u_regs[UREG_I1] = 1;
/* Set the second return value for the parent. */
regs->u_regs[UREG_I1] = 0;
if (clone_flags & CLONE_SETTLS)
t->kregs->u_regs[UREG_G7] = regs->u_regs[UREG_I3];
return 0;
}
/* TIF_MCDPER in thread info flags for current task is updated lazily upon
* a context switch. Update this flag in current task's thread flags
* before dup so the dup'd task will inherit the current TIF_MCDPER flag.
*/
int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
{
if (adi_capable()) {
register unsigned long tmp_mcdper;
__asm__ __volatile__(
".word 0x83438000\n\t" /* rd %mcdper, %g1 */
"mov %%g1, %0\n\t"
: "=r" (tmp_mcdper)
:
: "g1");
if (tmp_mcdper)
set_thread_flag(TIF_MCDPER);
else
clear_thread_flag(TIF_MCDPER);
}
*dst = *src;
return 0;
}
typedef struct {
union {
unsigned int pr_regs[32];
unsigned long pr_dregs[16];
} pr_fr;
unsigned int __unused;
unsigned int pr_fsr;
unsigned char pr_qcnt;
unsigned char pr_q_entrysize;
unsigned char pr_en;
unsigned int pr_q[64];
} elf_fpregset_t32;
/*
* fill in the fpu structure for a core dump.
*/
int dump_fpu (struct pt_regs * regs, elf_fpregset_t * fpregs)
{
unsigned long *kfpregs = current_thread_info()->fpregs;
unsigned long fprs = current_thread_info()->fpsaved[0];
if (test_thread_flag(TIF_32BIT)) {
elf_fpregset_t32 *fpregs32 = (elf_fpregset_t32 *)fpregs;
if (fprs & FPRS_DL)
memcpy(&fpregs32->pr_fr.pr_regs[0], kfpregs,
sizeof(unsigned int) * 32);
else
memset(&fpregs32->pr_fr.pr_regs[0], 0,
sizeof(unsigned int) * 32);
fpregs32->pr_qcnt = 0;
fpregs32->pr_q_entrysize = 8;
memset(&fpregs32->pr_q[0], 0,
(sizeof(unsigned int) * 64));
if (fprs & FPRS_FEF) {
fpregs32->pr_fsr = (unsigned int) current_thread_info()->xfsr[0];
fpregs32->pr_en = 1;
} else {
fpregs32->pr_fsr = 0;
fpregs32->pr_en = 0;
}
} else {
if(fprs & FPRS_DL)
memcpy(&fpregs->pr_regs[0], kfpregs,
sizeof(unsigned int) * 32);
else
memset(&fpregs->pr_regs[0], 0,
sizeof(unsigned int) * 32);
if(fprs & FPRS_DU)
memcpy(&fpregs->pr_regs[16], kfpregs+16,
sizeof(unsigned int) * 32);
else
memset(&fpregs->pr_regs[16], 0,
sizeof(unsigned int) * 32);
if(fprs & FPRS_FEF) {
fpregs->pr_fsr = current_thread_info()->xfsr[0];
fpregs->pr_gsr = current_thread_info()->gsr[0];
} else {
fpregs->pr_fsr = fpregs->pr_gsr = 0;
}
fpregs->pr_fprs = fprs;
}
return 1;
}
EXPORT_SYMBOL(dump_fpu);
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;
if (!task || task == current ||
task->state == TASK_RUNNING)
goto out;
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;
}
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