powerpc/cpumask: Update some comments
[safe/jmp/linux-2.6] / arch / powerpc / kernel / process.c
index e394676..9d255b4 100644 (file)
@@ -1,6 +1,4 @@
 /*
- *  arch/ppc/kernel/process.c
- *
  *  Derived from "arch/i386/kernel/process.c"
  *    Copyright (C) 1995  Linus Torvalds
  *
  *  2 of the License, or (at your option) any later version.
  */
 
-#include <linux/config.h>
 #include <linux/errno.h>
 #include <linux/sched.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/smp.h>
-#include <linux/smp_lock.h>
 #include <linux/stddef.h>
 #include <linux/unistd.h>
 #include <linux/ptrace.h>
 #include <linux/kallsyms.h>
 #include <linux/mqueue.h>
 #include <linux/hardirq.h>
+#include <linux/utsname.h>
+#include <linux/ftrace.h>
+#include <linux/kernel_stat.h>
+#include <linux/personality.h>
+#include <linux/random.h>
 
 #include <asm/pgtable.h>
 #include <asm/uaccess.h>
 #include <asm/processor.h>
 #include <asm/mmu.h>
 #include <asm/prom.h>
+#include <asm/machdep.h>
+#include <asm/time.h>
+#include <asm/syscalls.h>
+#ifdef CONFIG_PPC64
+#include <asm/firmware.h>
+#endif
+#include <linux/kprobes.h>
+#include <linux/kdebug.h>
 
 extern unsigned long _get_SP(void);
 
 #ifndef CONFIG_SMP
 struct task_struct *last_task_used_math = NULL;
 struct task_struct *last_task_used_altivec = NULL;
+struct task_struct *last_task_used_vsx = NULL;
 struct task_struct *last_task_used_spe = NULL;
 #endif
 
-static struct fs_struct init_fs = INIT_FS;
-static struct files_struct init_files = INIT_FILES;
-static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
-static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
-struct mm_struct init_mm = INIT_MM(init_mm);
-EXPORT_SYMBOL(init_mm);
-
-/* this is 8kB-aligned so we can get to the thread_info struct
-   at the base of it from the stack pointer with 1 integer instruction. */
-union thread_union init_thread_union
-       __attribute__((__section__(".data.init_task"))) =
-{ INIT_THREAD_INFO(init_task) };
-
-/* initial task structure */
-struct task_struct init_task = INIT_TASK(init_task);
-EXPORT_SYMBOL(init_task);
-
-/* only used to get secondary processor up */
-struct task_struct *current_set[NR_CPUS] = {&init_task, };
-
 /*
  * Make sure the floating-point register state in the
  * the thread_struct is up to date for task tsk.
@@ -100,7 +90,7 @@ void flush_fp_to_thread(struct task_struct *tsk)
                         */
                        BUG_ON(tsk != current);
 #endif
-                       giveup_fpu(current);
+                       giveup_fpu(tsk);
                }
                preempt_enable();
        }
@@ -121,17 +111,6 @@ void enable_kernel_fp(void)
 }
 EXPORT_SYMBOL(enable_kernel_fp);
 
-int dump_task_fpu(struct task_struct *tsk, elf_fpregset_t *fpregs)
-{
-       if (!tsk->thread.regs)
-               return 0;
-       flush_fp_to_thread(current);
-
-       memcpy(fpregs, &tsk->thread.fpr[0], sizeof(*fpregs));
-
-       return 1;
-}
-
 #ifdef CONFIG_ALTIVEC
 void enable_kernel_altivec(void)
 {
@@ -160,19 +139,53 @@ void flush_altivec_to_thread(struct task_struct *tsk)
 #ifdef CONFIG_SMP
                        BUG_ON(tsk != current);
 #endif
-                       giveup_altivec(current);
+                       giveup_altivec(tsk);
                }
                preempt_enable();
        }
 }
+#endif /* CONFIG_ALTIVEC */
 
-int dump_task_altivec(struct pt_regs *regs, elf_vrregset_t *vrregs)
+#ifdef CONFIG_VSX
+#if 0
+/* not currently used, but some crazy RAID module might want to later */
+void enable_kernel_vsx(void)
 {
-       flush_altivec_to_thread(current);
-       memcpy(vrregs, &current->thread.vr[0], sizeof(*vrregs));
-       return 1;
+       WARN_ON(preemptible());
+
+#ifdef CONFIG_SMP
+       if (current->thread.regs && (current->thread.regs->msr & MSR_VSX))
+               giveup_vsx(current);
+       else
+               giveup_vsx(NULL);       /* just enable vsx for kernel - force */
+#else
+       giveup_vsx(last_task_used_vsx);
+#endif /* CONFIG_SMP */
+}
+EXPORT_SYMBOL(enable_kernel_vsx);
+#endif
+
+void giveup_vsx(struct task_struct *tsk)
+{
+       giveup_fpu(tsk);
+       giveup_altivec(tsk);
+       __giveup_vsx(tsk);
 }
-#endif /* CONFIG_ALTIVEC */
+
+void flush_vsx_to_thread(struct task_struct *tsk)
+{
+       if (tsk->thread.regs) {
+               preempt_disable();
+               if (tsk->thread.regs->msr & MSR_VSX) {
+#ifdef CONFIG_SMP
+                       BUG_ON(tsk != current);
+#endif
+                       giveup_vsx(tsk);
+               }
+               preempt_enable();
+       }
+}
+#endif /* CONFIG_VSX */
 
 #ifdef CONFIG_SPE
 
@@ -199,45 +212,179 @@ void flush_spe_to_thread(struct task_struct *tsk)
 #ifdef CONFIG_SMP
                        BUG_ON(tsk != current);
 #endif
-                       giveup_spe(current);
+                       giveup_spe(tsk);
                }
                preempt_enable();
        }
 }
+#endif /* CONFIG_SPE */
 
-int dump_spe(struct pt_regs *regs, elf_vrregset_t *evrregs)
+#ifndef CONFIG_SMP
+/*
+ * If we are doing lazy switching of CPU state (FP, altivec or SPE),
+ * and the current task has some state, discard it.
+ */
+void discard_lazy_cpu_state(void)
 {
-       flush_spe_to_thread(current);
-       /* We copy u32 evr[32] + u64 acc + u32 spefscr -> 35 */
-       memcpy(evrregs, &current->thread.evr[0], sizeof(u32) * 35);
-       return 1;
+       preempt_disable();
+       if (last_task_used_math == current)
+               last_task_used_math = NULL;
+#ifdef CONFIG_ALTIVEC
+       if (last_task_used_altivec == current)
+               last_task_used_altivec = NULL;
+#endif /* CONFIG_ALTIVEC */
+#ifdef CONFIG_VSX
+       if (last_task_used_vsx == current)
+               last_task_used_vsx = NULL;
+#endif /* CONFIG_VSX */
+#ifdef CONFIG_SPE
+       if (last_task_used_spe == current)
+               last_task_used_spe = NULL;
+#endif
+       preempt_enable();
+}
+#endif /* CONFIG_SMP */
+
+#ifdef CONFIG_PPC_ADV_DEBUG_REGS
+void do_send_trap(struct pt_regs *regs, unsigned long address,
+                 unsigned long error_code, int signal_code, int breakpt)
+{
+       siginfo_t info;
+
+       if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code,
+                       11, SIGSEGV) == NOTIFY_STOP)
+               return;
+
+       /* Deliver the signal to userspace */
+       info.si_signo = SIGTRAP;
+       info.si_errno = breakpt;        /* breakpoint or watchpoint id */
+       info.si_code = signal_code;
+       info.si_addr = (void __user *)address;
+       force_sig_info(SIGTRAP, &info, current);
+}
+#else  /* !CONFIG_PPC_ADV_DEBUG_REGS */
+void do_dabr(struct pt_regs *regs, unsigned long address,
+                   unsigned long error_code)
+{
+       siginfo_t info;
+
+       if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code,
+                       11, SIGSEGV) == NOTIFY_STOP)
+               return;
+
+       if (debugger_dabr_match(regs))
+               return;
+
+       /* Clear the DABR */
+       set_dabr(0);
+
+       /* Deliver the signal to userspace */
+       info.si_signo = SIGTRAP;
+       info.si_errno = 0;
+       info.si_code = TRAP_HWBKPT;
+       info.si_addr = (void __user *)address;
+       force_sig_info(SIGTRAP, &info, current);
+}
+#endif /* CONFIG_PPC_ADV_DEBUG_REGS */
+
+static DEFINE_PER_CPU(unsigned long, current_dabr);
+
+#ifdef CONFIG_PPC_ADV_DEBUG_REGS
+/*
+ * Set the debug registers back to their default "safe" values.
+ */
+static void set_debug_reg_defaults(struct thread_struct *thread)
+{
+       thread->iac1 = thread->iac2 = 0;
+#if CONFIG_PPC_ADV_DEBUG_IACS > 2
+       thread->iac3 = thread->iac4 = 0;
+#endif
+       thread->dac1 = thread->dac2 = 0;
+#if CONFIG_PPC_ADV_DEBUG_DVCS > 0
+       thread->dvc1 = thread->dvc2 = 0;
+#endif
+       thread->dbcr0 = 0;
+#ifdef CONFIG_BOOKE
+       /*
+        * Force User/Supervisor bits to b11 (user-only MSR[PR]=1)
+        */
+       thread->dbcr1 = DBCR1_IAC1US | DBCR1_IAC2US |   \
+                       DBCR1_IAC3US | DBCR1_IAC4US;
+       /*
+        * Force Data Address Compare User/Supervisor bits to be User-only
+        * (0b11 MSR[PR]=1) and set all other bits in DBCR2 register to be 0.
+        */
+       thread->dbcr2 = DBCR2_DAC1US | DBCR2_DAC2US;
+#else
+       thread->dbcr1 = 0;
+#endif
 }
-#endif /* CONFIG_SPE */
 
-static void set_dabr_spr(unsigned long val)
+static void prime_debug_regs(struct thread_struct *thread)
 {
-       mtspr(SPRN_DABR, val);
+       mtspr(SPRN_IAC1, thread->iac1);
+       mtspr(SPRN_IAC2, thread->iac2);
+#if CONFIG_PPC_ADV_DEBUG_IACS > 2
+       mtspr(SPRN_IAC3, thread->iac3);
+       mtspr(SPRN_IAC4, thread->iac4);
+#endif
+       mtspr(SPRN_DAC1, thread->dac1);
+       mtspr(SPRN_DAC2, thread->dac2);
+#if CONFIG_PPC_ADV_DEBUG_DVCS > 0
+       mtspr(SPRN_DVC1, thread->dvc1);
+       mtspr(SPRN_DVC2, thread->dvc2);
+#endif
+       mtspr(SPRN_DBCR0, thread->dbcr0);
+       mtspr(SPRN_DBCR1, thread->dbcr1);
+#ifdef CONFIG_BOOKE
+       mtspr(SPRN_DBCR2, thread->dbcr2);
+#endif
 }
+/*
+ * Unless neither the old or new thread are making use of the
+ * debug registers, set the debug registers from the values
+ * stored in the new thread.
+ */
+static void switch_booke_debug_regs(struct thread_struct *new_thread)
+{
+       if ((current->thread.dbcr0 & DBCR0_IDM)
+               || (new_thread->dbcr0 & DBCR0_IDM))
+                       prime_debug_regs(new_thread);
+}
+#else  /* !CONFIG_PPC_ADV_DEBUG_REGS */
+static void set_debug_reg_defaults(struct thread_struct *thread)
+{
+       if (thread->dabr) {
+               thread->dabr = 0;
+               set_dabr(0);
+       }
+}
+#endif /* CONFIG_PPC_ADV_DEBUG_REGS */
 
 int set_dabr(unsigned long dabr)
 {
-       int ret = 0;
+       __get_cpu_var(current_dabr) = dabr;
 
-#ifdef CONFIG_PPC64
-       if (firmware_has_feature(FW_FEATURE_XDABR)) {
-               /* We want to catch accesses from kernel and userspace */
-               unsigned long flags = H_DABRX_KERNEL|H_DABRX_USER;
-               ret = plpar_set_xdabr(dabr, flags);
-       } else if (firmware_has_feature(FW_FEATURE_DABR)) {
-               ret = plpar_set_dabr(dabr);
-       } else
+       if (ppc_md.set_dabr)
+               return ppc_md.set_dabr(dabr);
+
+       /* XXX should we have a CPU_FTR_HAS_DABR ? */
+#ifdef CONFIG_PPC_ADV_DEBUG_REGS
+       mtspr(SPRN_DAC1, dabr);
+#ifdef CONFIG_PPC_47x
+       isync();
+#endif
+#elif defined(CONFIG_PPC_BOOK3S)
+       mtspr(SPRN_DABR, dabr);
 #endif
-               set_dabr_spr(dabr);
 
-       return ret;
+
+       return 0;
 }
 
-static DEFINE_PER_CPU(unsigned long, current_dabr);
+#ifdef CONFIG_PPC64
+DEFINE_PER_CPU(struct cpu_usage, cpu_usage_array);
+#endif
 
 struct task_struct *__switch_to(struct task_struct *prev,
        struct task_struct *new)
@@ -272,12 +419,12 @@ struct task_struct *__switch_to(struct task_struct *prev,
         */
        if (prev->thread.regs && (prev->thread.regs->msr & MSR_VEC))
                giveup_altivec(prev);
-       /* Avoid the trap.  On smp this this never happens since
-        * we don't set last_task_used_altivec -- Cort
-        */
-       if (new->thread.regs && last_task_used_altivec == new)
-               new->thread.regs->msr |= MSR_VEC;
 #endif /* CONFIG_ALTIVEC */
+#ifdef CONFIG_VSX
+       if (prev->thread.regs && (prev->thread.regs->msr & MSR_VSX))
+               /* VMX and FPU registers are already save here */
+               __giveup_vsx(prev);
+#endif /* CONFIG_VSX */
 #ifdef CONFIG_SPE
        /*
         * If the previous thread used spe in the last quantum
@@ -288,24 +435,67 @@ struct task_struct *__switch_to(struct task_struct *prev,
         */
        if ((prev->thread.regs && (prev->thread.regs->msr & MSR_SPE)))
                giveup_spe(prev);
+#endif /* CONFIG_SPE */
+
+#else  /* CONFIG_SMP */
+#ifdef CONFIG_ALTIVEC
+       /* Avoid the trap.  On smp this this never happens since
+        * we don't set last_task_used_altivec -- Cort
+        */
+       if (new->thread.regs && last_task_used_altivec == new)
+               new->thread.regs->msr |= MSR_VEC;
+#endif /* CONFIG_ALTIVEC */
+#ifdef CONFIG_VSX
+       if (new->thread.regs && last_task_used_vsx == new)
+               new->thread.regs->msr |= MSR_VSX;
+#endif /* CONFIG_VSX */
+#ifdef CONFIG_SPE
        /* Avoid the trap.  On smp this this never happens since
         * we don't set last_task_used_spe
         */
        if (new->thread.regs && last_task_used_spe == new)
                new->thread.regs->msr |= MSR_SPE;
 #endif /* CONFIG_SPE */
+
 #endif /* CONFIG_SMP */
 
-#ifdef CONFIG_PPC64    /* for now */
-       if (unlikely(__get_cpu_var(current_dabr) != new->thread.dabr)) {
+#ifdef CONFIG_PPC_ADV_DEBUG_REGS
+       switch_booke_debug_regs(&new->thread);
+#else
+       if (unlikely(__get_cpu_var(current_dabr) != new->thread.dabr))
                set_dabr(new->thread.dabr);
-               __get_cpu_var(current_dabr) = new->thread.dabr;
-       }
 #endif
 
+
        new_thread = &new->thread;
        old_thread = &current->thread;
+
+#ifdef CONFIG_PPC64
+       /*
+        * Collect processor utilization data per process
+        */
+       if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
+               struct cpu_usage *cu = &__get_cpu_var(cpu_usage_array);
+               long unsigned start_tb, current_tb;
+               start_tb = old_thread->start_tb;
+               cu->current_tb = current_tb = mfspr(SPRN_PURR);
+               old_thread->accum_tb += (current_tb - start_tb);
+               new_thread->start_tb = current_tb;
+       }
+#endif
+
        local_irq_save(flags);
+
+       account_system_vtime(current);
+       account_process_vtime(current);
+       calculate_steal_time();
+
+       /*
+        * We can't take a PMU exception inside _switch() since there is a
+        * window where the kernel stack SLB and the kernel stack are out
+        * of sync. Hard disable here.
+        */
+       hard_irq_disable();
        last = _switch(old_thread, new_thread);
 
        local_irq_restore(flags);
@@ -313,37 +503,120 @@ struct task_struct *__switch_to(struct task_struct *prev,
        return last;
 }
 
+static int instructions_to_print = 16;
+
+static void show_instructions(struct pt_regs *regs)
+{
+       int i;
+       unsigned long pc = regs->nip - (instructions_to_print * 3 / 4 *
+                       sizeof(int));
+
+       printk("Instruction dump:");
+
+       for (i = 0; i < instructions_to_print; i++) {
+               int instr;
+
+               if (!(i % 8))
+                       printk("\n");
+
+#if !defined(CONFIG_BOOKE)
+               /* If executing with the IMMU off, adjust pc rather
+                * than print XXXXXXXX.
+                */
+               if (!(regs->msr & MSR_IR))
+                       pc = (unsigned long)phys_to_virt(pc);
+#endif
+
+               /* We use __get_user here *only* to avoid an OOPS on a
+                * bad address because the pc *should* only be a
+                * kernel address.
+                */
+               if (!__kernel_text_address(pc) ||
+                    __get_user(instr, (unsigned int __user *)pc)) {
+                       printk("XXXXXXXX ");
+               } else {
+                       if (regs->nip == pc)
+                               printk("<%08x> ", instr);
+                       else
+                               printk("%08x ", instr);
+               }
+
+               pc += sizeof(int);
+       }
+
+       printk("\n");
+}
+
+static struct regbit {
+       unsigned long bit;
+       const char *name;
+} msr_bits[] = {
+       {MSR_EE,        "EE"},
+       {MSR_PR,        "PR"},
+       {MSR_FP,        "FP"},
+       {MSR_VEC,       "VEC"},
+       {MSR_VSX,       "VSX"},
+       {MSR_ME,        "ME"},
+       {MSR_CE,        "CE"},
+       {MSR_DE,        "DE"},
+       {MSR_IR,        "IR"},
+       {MSR_DR,        "DR"},
+       {0,             NULL}
+};
+
+static void printbits(unsigned long val, struct regbit *bits)
+{
+       const char *sep = "";
+
+       printk("<");
+       for (; bits->bit; ++bits)
+               if (val & bits->bit) {
+                       printk("%s%s", sep, bits->name);
+                       sep = ",";
+               }
+       printk(">");
+}
+
+#ifdef CONFIG_PPC64
+#define REG            "%016lx"
+#define REGS_PER_LINE  4
+#define LAST_VOLATILE  13
+#else
+#define REG            "%08lx"
+#define REGS_PER_LINE  8
+#define LAST_VOLATILE  12
+#endif
+
 void show_regs(struct pt_regs * regs)
 {
        int i, trap;
 
-       printk("NIP: %08lX LR: %08lX SP: %08lX REGS: %p TRAP: %04lx    %s\n",
-              regs->nip, regs->link, regs->gpr[1], regs, regs->trap,
-              print_tainted());
-       printk("MSR: %08lx EE: %01x PR: %01x FP: %01x ME: %01x IR/DR: %01x%01x\n",
-              regs->msr, regs->msr&MSR_EE ? 1 : 0, regs->msr&MSR_PR ? 1 : 0,
-              regs->msr & MSR_FP ? 1 : 0,regs->msr&MSR_ME ? 1 : 0,
-              regs->msr&MSR_IR ? 1 : 0,
-              regs->msr&MSR_DR ? 1 : 0);
+       printk("NIP: "REG" LR: "REG" CTR: "REG"\n",
+              regs->nip, regs->link, regs->ctr);
+       printk("REGS: %p TRAP: %04lx   %s  (%s)\n",
+              regs, regs->trap, print_tainted(), init_utsname()->release);
+       printk("MSR: "REG" ", regs->msr);
+       printbits(regs->msr, msr_bits);
+       printk("  CR: %08lx  XER: %08lx\n", regs->ccr, regs->xer);
        trap = TRAP(regs);
        if (trap == 0x300 || trap == 0x600)
-               printk("DAR: %08lX, DSISR: %08lX\n", regs->dar, regs->dsisr);
-       printk("TASK = %p[%d] '%s' THREAD: %p\n",
-              current, current->pid, current->comm, current->thread_info);
-       printk("Last syscall: %ld ", current->thread.last_syscall);
+#ifdef CONFIG_PPC_ADV_DEBUG_REGS
+               printk("DEAR: "REG", ESR: "REG"\n", regs->dar, regs->dsisr);
+#else
+               printk("DAR: "REG", DSISR: "REG"\n", regs->dar, regs->dsisr);
+#endif
+       printk("TASK = %p[%d] '%s' THREAD: %p",
+              current, task_pid_nr(current), current->comm, task_thread_info(current));
 
 #ifdef CONFIG_SMP
-       printk(" CPU: %d", smp_processor_id());
+       printk(" CPU: %d", raw_smp_processor_id());
 #endif /* CONFIG_SMP */
 
        for (i = 0;  i < 32;  i++) {
-               long r;
-               if ((i % 8) == 0)
-                       printk("\n" KERN_INFO "GPR%02d: ", i);
-               if (__get_user(r, &regs->gpr[i]))
-                       break;
-               printk("%08lX ", r);
-               if (i == 12 && !FULL_REGS(regs))
+               if ((i % REGS_PER_LINE) == 0)
+                       printk("\nGPR%02d: ", i);
+               printk(REG " ", regs->gpr[i]);
+               if (i == LAST_VOLATILE && !FULL_REGS(regs))
                        break;
        }
        printk("\n");
@@ -352,51 +625,24 @@ void show_regs(struct pt_regs * regs)
         * Lookup NIP late so we have the best change of getting the
         * above info out without failing
         */
-       printk("NIP [%08lx] ", regs->nip);
-       print_symbol("%s\n", regs->nip);
-       printk("LR [%08lx] ", regs->link);
-       print_symbol("%s\n", regs->link);
+       printk("NIP ["REG"] %pS\n", regs->nip, (void *)regs->nip);
+       printk("LR ["REG"] %pS\n", regs->link, (void *)regs->link);
 #endif
        show_stack(current, (unsigned long *) regs->gpr[1]);
+       if (!user_mode(regs))
+               show_instructions(regs);
 }
 
 void exit_thread(void)
 {
-#ifndef CONFIG_SMP
-       if (last_task_used_math == current)
-               last_task_used_math = NULL;
-#ifdef CONFIG_ALTIVEC
-       if (last_task_used_altivec == current)
-               last_task_used_altivec = NULL;
-#endif /* CONFIG_ALTIVEC */
-#ifdef CONFIG_SPE
-       if (last_task_used_spe == current)
-               last_task_used_spe = NULL;
-#endif
-#endif /* CONFIG_SMP */
+       discard_lazy_cpu_state();
 }
 
 void flush_thread(void)
 {
-#ifndef CONFIG_SMP
-       if (last_task_used_math == current)
-               last_task_used_math = NULL;
-#ifdef CONFIG_ALTIVEC
-       if (last_task_used_altivec == current)
-               last_task_used_altivec = NULL;
-#endif /* CONFIG_ALTIVEC */
-#ifdef CONFIG_SPE
-       if (last_task_used_spe == current)
-               last_task_used_spe = NULL;
-#endif
-#endif /* CONFIG_SMP */
+       discard_lazy_cpu_state();
 
-#ifdef CONFIG_PPC64    /* for now */
-       if (current->thread.dabr) {
-               current->thread.dabr = 0;
-               set_dabr(0);
-       }
-#endif
+       set_debug_reg_defaults(&current->thread);
 }
 
 void
@@ -412,21 +658,20 @@ void prepare_to_copy(struct task_struct *tsk)
 {
        flush_fp_to_thread(current);
        flush_altivec_to_thread(current);
+       flush_vsx_to_thread(current);
        flush_spe_to_thread(current);
 }
 
 /*
  * Copy a thread..
  */
-int
-copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
-           unsigned long unused,
-           struct task_struct *p, struct pt_regs *regs)
+int copy_thread(unsigned long clone_flags, unsigned long usp,
+               unsigned long unused, struct task_struct *p,
+               struct pt_regs *regs)
 {
        struct pt_regs *childregs, *kregs;
        extern void ret_from_fork(void);
-       unsigned long sp = (unsigned long)p->thread_info + THREAD_SIZE;
-       unsigned long childframe;
+       unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
 
        CHECK_FULL_REGS(regs);
        /* Copy registers */
@@ -436,17 +681,26 @@ copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
        if ((childregs->msr & MSR_PR) == 0) {
                /* for kernel thread, set `current' and stackptr in new task */
                childregs->gpr[1] = sp + sizeof(struct pt_regs);
+#ifdef CONFIG_PPC32
                childregs->gpr[2] = (unsigned long) p;
+#else
+               clear_tsk_thread_flag(p, TIF_32BIT);
+#endif
                p->thread.regs = NULL;  /* no user register state */
        } else {
                childregs->gpr[1] = usp;
                p->thread.regs = childregs;
-               if (clone_flags & CLONE_SETTLS)
-                       childregs->gpr[2] = childregs->gpr[6];
+               if (clone_flags & CLONE_SETTLS) {
+#ifdef CONFIG_PPC64
+                       if (!test_thread_flag(TIF_32BIT))
+                               childregs->gpr[13] = childregs->gpr[6];
+                       else
+#endif
+                               childregs->gpr[2] = childregs->gpr[6];
+               }
        }
        childregs->gpr[3] = 0;  /* Result from fork() */
        sp -= STACK_FRAME_OVERHEAD;
-       childframe = sp;
 
        /*
         * The way this works is that at some point in the future
@@ -460,9 +714,36 @@ copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
        kregs = (struct pt_regs *) sp;
        sp -= STACK_FRAME_OVERHEAD;
        p->thread.ksp = sp;
-       kregs->nip = (unsigned long)ret_from_fork;
+       p->thread.ksp_limit = (unsigned long)task_stack_page(p) +
+                               _ALIGN_UP(sizeof(struct thread_info), 16);
 
-       p->thread.last_syscall = -1;
+#ifdef CONFIG_PPC_STD_MMU_64
+       if (cpu_has_feature(CPU_FTR_SLB)) {
+               unsigned long sp_vsid;
+               unsigned long llp = mmu_psize_defs[mmu_linear_psize].sllp;
+
+               if (cpu_has_feature(CPU_FTR_1T_SEGMENT))
+                       sp_vsid = get_kernel_vsid(sp, MMU_SEGSIZE_1T)
+                               << SLB_VSID_SHIFT_1T;
+               else
+                       sp_vsid = get_kernel_vsid(sp, MMU_SEGSIZE_256M)
+                               << SLB_VSID_SHIFT;
+               sp_vsid |= SLB_VSID_KERNEL | llp;
+               p->thread.ksp_vsid = sp_vsid;
+       }
+#endif /* CONFIG_PPC_STD_MMU_64 */
+
+       /*
+        * The PPC64 ABI makes use of a TOC to contain function 
+        * pointers.  The function (ret_from_except) is actually a pointer
+        * to the TOC entry.  The first entry is a pointer to the actual
+        * function.
+        */
+#ifdef CONFIG_PPC64
+       kregs->nip = *((unsigned long *)ret_from_fork);
+#else
+       kregs->nip = (unsigned long)ret_from_fork;
+#endif
 
        return 0;
 }
@@ -470,35 +751,80 @@ copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
 /*
  * Set up a thread for executing a new program
  */
-void start_thread(struct pt_regs *regs, unsigned long nip, unsigned long sp)
+void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
 {
+#ifdef CONFIG_PPC64
+       unsigned long load_addr = regs->gpr[2]; /* saved by ELF_PLAT_INIT */
+#endif
+
        set_fs(USER_DS);
+
+       /*
+        * If we exec out of a kernel thread then thread.regs will not be
+        * set.  Do it now.
+        */
+       if (!current->thread.regs) {
+               struct pt_regs *regs = task_stack_page(current) + THREAD_SIZE;
+               current->thread.regs = regs - 1;
+       }
+
        memset(regs->gpr, 0, sizeof(regs->gpr));
        regs->ctr = 0;
        regs->link = 0;
        regs->xer = 0;
        regs->ccr = 0;
-       regs->mq = 0;
-       regs->nip = nip;
        regs->gpr[1] = sp;
+
+       /*
+        * We have just cleared all the nonvolatile GPRs, so make
+        * FULL_REGS(regs) return true.  This is necessary to allow
+        * ptrace to examine the thread immediately after exec.
+        */
+       regs->trap &= ~1UL;
+
+#ifdef CONFIG_PPC32
+       regs->mq = 0;
+       regs->nip = start;
        regs->msr = MSR_USER;
-#ifndef CONFIG_SMP
-       if (last_task_used_math == current)
-               last_task_used_math = NULL;
-#ifdef CONFIG_ALTIVEC
-       if (last_task_used_altivec == current)
-               last_task_used_altivec = NULL;
+#else
+       if (!test_thread_flag(TIF_32BIT)) {
+               unsigned long entry, toc;
+
+               /* start is a relocated pointer to the function descriptor for
+                * the elf _start routine.  The first entry in the function
+                * descriptor is the entry address of _start and the second
+                * entry is the TOC value we need to use.
+                */
+               __get_user(entry, (unsigned long __user *)start);
+               __get_user(toc, (unsigned long __user *)start+1);
+
+               /* Check whether the e_entry function descriptor entries
+                * need to be relocated before we can use them.
+                */
+               if (load_addr != 0) {
+                       entry += load_addr;
+                       toc   += load_addr;
+               }
+               regs->nip = entry;
+               regs->gpr[2] = toc;
+               regs->msr = MSR_USER64;
+       } else {
+               regs->nip = start;
+               regs->gpr[2] = 0;
+               regs->msr = MSR_USER32;
+       }
 #endif
-#ifdef CONFIG_SPE
-       if (last_task_used_spe == current)
-               last_task_used_spe = NULL;
+
+       discard_lazy_cpu_state();
+#ifdef CONFIG_VSX
+       current->thread.used_vsr = 0;
 #endif
-#endif /* CONFIG_SMP */
        memset(current->thread.fpr, 0, sizeof(current->thread.fpr));
-       current->thread.fpscr = 0;
+       current->thread.fpscr.val = 0;
 #ifdef CONFIG_ALTIVEC
        memset(current->thread.vr, 0, sizeof(current->thread.vr));
        memset(&current->thread.vscr, 0, sizeof(current->thread.vscr));
+       current->thread.vscr.u[3] = 0x00010000; /* Java mode disabled */
        current->thread.vrsave = 0;
        current->thread.used_vr = 0;
 #endif /* CONFIG_ALTIVEC */
@@ -523,24 +849,29 @@ int set_fpexc_mode(struct task_struct *tsk, unsigned int val)
         * mode (asyn, precise, disabled) for 'Classic' FP. */
        if (val & PR_FP_EXC_SW_ENABLE) {
 #ifdef CONFIG_SPE
-               tsk->thread.fpexc_mode = val &
-                       (PR_FP_EXC_SW_ENABLE | PR_FP_ALL_EXCEPT);
+               if (cpu_has_feature(CPU_FTR_SPE)) {
+                       tsk->thread.fpexc_mode = val &
+                               (PR_FP_EXC_SW_ENABLE | PR_FP_ALL_EXCEPT);
+                       return 0;
+               } else {
+                       return -EINVAL;
+               }
 #else
                return -EINVAL;
 #endif
-       } else {
-               /* on a CONFIG_SPE this does not hurt us.  The bits that
-                * __pack_fe01 use do not overlap with bits used for
-                * PR_FP_EXC_SW_ENABLE.  Additionally, the MSR[FE0,FE1] bits
-                * on CONFIG_SPE implementations are reserved so writing to
-                * them does not change anything */
-               if (val > PR_FP_EXC_PRECISE)
-                       return -EINVAL;
-               tsk->thread.fpexc_mode = __pack_fe01(val);
-               if (regs != NULL && (regs->msr & MSR_FP) != 0)
-                       regs->msr = (regs->msr & ~(MSR_FE0|MSR_FE1))
-                               | tsk->thread.fpexc_mode;
        }
+
+       /* on a CONFIG_SPE this does not hurt us.  The bits that
+        * __pack_fe01 use do not overlap with bits used for
+        * PR_FP_EXC_SW_ENABLE.  Additionally, the MSR[FE0,FE1] bits
+        * on CONFIG_SPE implementations are reserved so writing to
+        * them does not change anything */
+       if (val > PR_FP_EXC_PRECISE)
+               return -EINVAL;
+       tsk->thread.fpexc_mode = __pack_fe01(val);
+       if (regs != NULL && (regs->msr & MSR_FP) != 0)
+               regs->msr = (regs->msr & ~(MSR_FE0|MSR_FE1))
+                       | tsk->thread.fpexc_mode;
        return 0;
 }
 
@@ -550,7 +881,10 @@ int get_fpexc_mode(struct task_struct *tsk, unsigned long adr)
 
        if (tsk->thread.fpexc_mode & PR_FP_EXC_SW_ENABLE)
 #ifdef CONFIG_SPE
-               val = tsk->thread.fpexc_mode;
+               if (cpu_has_feature(CPU_FTR_SPE))
+                       val = tsk->thread.fpexc_mode;
+               else
+                       return -EINVAL;
 #else
                return -EINVAL;
 #endif
@@ -559,6 +893,63 @@ int get_fpexc_mode(struct task_struct *tsk, unsigned long adr)
        return put_user(val, (unsigned int __user *) adr);
 }
 
+int set_endian(struct task_struct *tsk, unsigned int val)
+{
+       struct pt_regs *regs = tsk->thread.regs;
+
+       if ((val == PR_ENDIAN_LITTLE && !cpu_has_feature(CPU_FTR_REAL_LE)) ||
+           (val == PR_ENDIAN_PPC_LITTLE && !cpu_has_feature(CPU_FTR_PPC_LE)))
+               return -EINVAL;
+
+       if (regs == NULL)
+               return -EINVAL;
+
+       if (val == PR_ENDIAN_BIG)
+               regs->msr &= ~MSR_LE;
+       else if (val == PR_ENDIAN_LITTLE || val == PR_ENDIAN_PPC_LITTLE)
+               regs->msr |= MSR_LE;
+       else
+               return -EINVAL;
+
+       return 0;
+}
+
+int get_endian(struct task_struct *tsk, unsigned long adr)
+{
+       struct pt_regs *regs = tsk->thread.regs;
+       unsigned int val;
+
+       if (!cpu_has_feature(CPU_FTR_PPC_LE) &&
+           !cpu_has_feature(CPU_FTR_REAL_LE))
+               return -EINVAL;
+
+       if (regs == NULL)
+               return -EINVAL;
+
+       if (regs->msr & MSR_LE) {
+               if (cpu_has_feature(CPU_FTR_REAL_LE))
+                       val = PR_ENDIAN_LITTLE;
+               else
+                       val = PR_ENDIAN_PPC_LITTLE;
+       } else
+               val = PR_ENDIAN_BIG;
+
+       return put_user(val, (unsigned int __user *)adr);
+}
+
+int set_unalign_ctl(struct task_struct *tsk, unsigned int val)
+{
+       tsk->thread.align_ctl = val;
+       return 0;
+}
+
+int get_unalign_ctl(struct task_struct *tsk, unsigned long adr)
+{
+       return put_user(tsk->thread.align_ctl, (unsigned int __user *)adr);
+}
+
+#define TRUNC_PTR(x)   ((typeof(x))(((unsigned long)(x)) & 0xffffffff))
+
 int sys_clone(unsigned long clone_flags, unsigned long usp,
              int __user *parent_tidp, void __user *child_threadptr,
              int __user *child_tidp, int p6,
@@ -567,6 +958,12 @@ int sys_clone(unsigned long clone_flags, unsigned long usp,
        CHECK_FULL_REGS(regs);
        if (usp == 0)
                usp = regs->gpr[1];     /* stack pointer for child */
+#ifdef CONFIG_PPC64
+       if (test_thread_flag(TIF_32BIT)) {
+               parent_tidp = TRUNC_PTR(parent_tidp);
+               child_tidp = TRUNC_PTR(child_tidp);
+       }
+#endif
        return do_fork(clone_flags, usp, regs, 0, parent_tidp, child_tidp);
 }
 
@@ -592,7 +989,7 @@ int sys_execve(unsigned long a0, unsigned long a1, unsigned long a2,
               struct pt_regs *regs)
 {
        int error;
-       char * filename;
+       char *filename;
 
        filename = getname((char __user *) a0);
        error = PTR_ERR(filename);
@@ -603,54 +1000,98 @@ int sys_execve(unsigned long a0, unsigned long a1, unsigned long a2,
        flush_spe_to_thread(current);
        error = do_execve(filename, (char __user * __user *) a1,
                          (char __user * __user *) a2, regs);
-       if (error == 0) {
-               task_lock(current);
-               current->ptrace &= ~PT_DTRACE;
-               task_unlock(current);
-       }
        putname(filename);
 out:
        return error;
 }
 
-static int validate_sp(unsigned long sp, struct task_struct *p,
-                      unsigned long nbytes)
+#ifdef CONFIG_IRQSTACKS
+static inline int valid_irq_stack(unsigned long sp, struct task_struct *p,
+                                 unsigned long nbytes)
 {
-       unsigned long stack_page = (unsigned long)p->thread_info;
+       unsigned long stack_page;
+       unsigned long cpu = task_cpu(p);
 
-       if (sp >= stack_page + sizeof(struct thread_struct)
-           && sp <= stack_page + THREAD_SIZE - nbytes)
-               return 1;
+       /*
+        * Avoid crashing if the stack has overflowed and corrupted
+        * task_cpu(p), which is in the thread_info struct.
+        */
+       if (cpu < NR_CPUS && cpu_possible(cpu)) {
+               stack_page = (unsigned long) hardirq_ctx[cpu];
+               if (sp >= stack_page + sizeof(struct thread_struct)
+                   && sp <= stack_page + THREAD_SIZE - nbytes)
+                       return 1;
+
+               stack_page = (unsigned long) softirq_ctx[cpu];
+               if (sp >= stack_page + sizeof(struct thread_struct)
+                   && sp <= stack_page + THREAD_SIZE - nbytes)
+                       return 1;
+       }
+       return 0;
+}
 
-#ifdef CONFIG_IRQSTACKS
-       stack_page = (unsigned long) hardirq_ctx[task_cpu(p)];
-       if (sp >= stack_page + sizeof(struct thread_struct)
-           && sp <= stack_page + THREAD_SIZE - nbytes)
-               return 1;
+#else
+#define valid_irq_stack(sp, p, nb)     0
+#endif /* CONFIG_IRQSTACKS */
+
+int validate_sp(unsigned long sp, struct task_struct *p,
+                      unsigned long nbytes)
+{
+       unsigned long stack_page = (unsigned long)task_stack_page(p);
 
-       stack_page = (unsigned long) softirq_ctx[task_cpu(p)];
        if (sp >= stack_page + sizeof(struct thread_struct)
            && sp <= stack_page + THREAD_SIZE - nbytes)
                return 1;
-#endif
 
-       return 0;
+       return valid_irq_stack(sp, p, nbytes);
 }
 
-void dump_stack(void)
+EXPORT_SYMBOL(validate_sp);
+
+unsigned long get_wchan(struct task_struct *p)
 {
-       show_stack(current, NULL);
+       unsigned long ip, sp;
+       int count = 0;
+
+       if (!p || p == current || p->state == TASK_RUNNING)
+               return 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))
+                       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;
 }
 
-EXPORT_SYMBOL(dump_stack);
+static int kstack_depth_to_print = CONFIG_PRINT_STACK_DEPTH;
 
 void show_stack(struct task_struct *tsk, unsigned long *stack)
 {
-       unsigned long sp, stack_top, prev_sp, ret;
+       unsigned long sp, ip, lr, newsp;
        int count = 0;
-       unsigned long next_exc = 0;
-       struct pt_regs *regs;
-       extern char ret_from_except, ret_from_except_full, ret_from_syscall;
+       int firstframe = 1;
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+       int curr_frame = current->curr_ret_stack;
+       extern void return_to_handler(void);
+       unsigned long rth = (unsigned long)return_to_handler;
+       unsigned long mrth = -1;
+#ifdef CONFIG_PPC64
+       extern void mod_return_to_handler(void);
+       rth = *(unsigned long *)rth;
+       mrth = (unsigned long)mod_return_to_handler;
+       mrth = *(unsigned long *)mrth;
+#endif
+#endif
 
        sp = (unsigned long) stack;
        if (tsk == NULL)
@@ -662,65 +1103,168 @@ void show_stack(struct task_struct *tsk, unsigned long *stack)
                        sp = tsk->thread.ksp;
        }
 
-       prev_sp = (unsigned long) (tsk->thread_info + 1);
-       stack_top = (unsigned long) tsk->thread_info + THREAD_SIZE;
-       while (count < 16 && sp > prev_sp && sp < stack_top && (sp & 3) == 0) {
-               if (count == 0) {
-                       printk("Call trace:");
-#ifdef CONFIG_KALLSYMS
-                       printk("\n");
+       lr = 0;
+       printk("Call Trace:\n");
+       do {
+               if (!validate_sp(sp, tsk, STACK_FRAME_OVERHEAD))
+                       return;
+
+               stack = (unsigned long *) sp;
+               newsp = stack[0];
+               ip = stack[STACK_FRAME_LR_SAVE];
+               if (!firstframe || ip != lr) {
+                       printk("["REG"] ["REG"] %pS", sp, ip, (void *)ip);
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+                       if ((ip == rth || ip == mrth) && curr_frame >= 0) {
+                               printk(" (%pS)",
+                                      (void *)current->ret_stack[curr_frame].ret);
+                               curr_frame--;
+                       }
 #endif
-               } else {
-                       if (next_exc) {
-                               ret = next_exc;
-                               next_exc = 0;
-                       } else
-                               ret = *(unsigned long *)(sp + 4);
-                       printk(" [%08lx] ", ret);
-#ifdef CONFIG_KALLSYMS
-                       print_symbol("%s", ret);
+                       if (firstframe)
+                               printk(" (unreliable)");
                        printk("\n");
-#endif
-                       if (ret == (unsigned long) &ret_from_except
-                           || ret == (unsigned long) &ret_from_except_full
-                           || ret == (unsigned long) &ret_from_syscall) {
-                               /* sp + 16 points to an exception frame */
-                               regs = (struct pt_regs *) (sp + 16);
-                               if (sp + 16 + sizeof(*regs) <= stack_top)
-                                       next_exc = regs->nip;
-                       }
                }
-               ++count;
-               sp = *(unsigned long *)sp;
+               firstframe = 0;
+
+               /*
+                * See if this is an exception frame.
+                * We look for the "regshere" marker in the current frame.
+                */
+               if (validate_sp(sp, tsk, STACK_INT_FRAME_SIZE)
+                   && stack[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
+                       struct pt_regs *regs = (struct pt_regs *)
+                               (sp + STACK_FRAME_OVERHEAD);
+                       lr = regs->link;
+                       printk("--- Exception: %lx at %pS\n    LR = %pS\n",
+                              regs->trap, (void *)regs->nip, (void *)lr);
+                       firstframe = 1;
+               }
+
+               sp = newsp;
+       } while (count++ < kstack_depth_to_print);
+}
+
+void dump_stack(void)
+{
+       show_stack(current, NULL);
+}
+EXPORT_SYMBOL(dump_stack);
+
+#ifdef CONFIG_PPC64
+void ppc64_runlatch_on(void)
+{
+       unsigned long ctrl;
+
+       if (cpu_has_feature(CPU_FTR_CTRL) && !test_thread_flag(TIF_RUNLATCH)) {
+               HMT_medium();
+
+               ctrl = mfspr(SPRN_CTRLF);
+               ctrl |= CTRL_RUNLATCH;
+               mtspr(SPRN_CTRLT, ctrl);
+
+               set_thread_flag(TIF_RUNLATCH);
        }
-#ifndef CONFIG_KALLSYMS
-       if (count > 0)
-               printk("\n");
+}
+
+void ppc64_runlatch_off(void)
+{
+       unsigned long ctrl;
+
+       if (cpu_has_feature(CPU_FTR_CTRL) && test_thread_flag(TIF_RUNLATCH)) {
+               HMT_medium();
+
+               clear_thread_flag(TIF_RUNLATCH);
+
+               ctrl = mfspr(SPRN_CTRLF);
+               ctrl &= ~CTRL_RUNLATCH;
+               mtspr(SPRN_CTRLT, ctrl);
+       }
+}
 #endif
+
+#if THREAD_SHIFT < PAGE_SHIFT
+
+static struct kmem_cache *thread_info_cache;
+
+struct thread_info *alloc_thread_info(struct task_struct *tsk)
+{
+       struct thread_info *ti;
+
+       ti = kmem_cache_alloc(thread_info_cache, GFP_KERNEL);
+       if (unlikely(ti == NULL))
+               return NULL;
+#ifdef CONFIG_DEBUG_STACK_USAGE
+       memset(ti, 0, THREAD_SIZE);
+#endif
+       return ti;
 }
 
-unsigned long get_wchan(struct task_struct *p)
+void free_thread_info(struct thread_info *ti)
 {
-       unsigned long ip, sp;
-       int count = 0;
+       kmem_cache_free(thread_info_cache, ti);
+}
 
-       if (!p || p == current || p->state == TASK_RUNNING)
-               return 0;
+void thread_info_cache_init(void)
+{
+       thread_info_cache = kmem_cache_create("thread_info", THREAD_SIZE,
+                                             THREAD_SIZE, 0, NULL);
+       BUG_ON(thread_info_cache == NULL);
+}
 
-       sp = p->thread.ksp;
-       if (!validate_sp(sp, p, 16))
-               return 0;
+#endif /* THREAD_SHIFT < PAGE_SHIFT */
 
-       do {
-               sp = *(unsigned long *)sp;
-               if (!validate_sp(sp, p, 16))
-                       return 0;
-               if (count > 0) {
-                       ip = *(unsigned long *)(sp + 4);
-                       if (!in_sched_functions(ip))
-                               return ip;
-               }
-       } while (count++ < 16);
-       return 0;
+unsigned long arch_align_stack(unsigned long sp)
+{
+       if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
+               sp -= get_random_int() & ~PAGE_MASK;
+       return sp & ~0xf;
+}
+
+static inline unsigned long brk_rnd(void)
+{
+        unsigned long rnd = 0;
+
+       /* 8MB for 32bit, 1GB for 64bit */
+       if (is_32bit_task())
+               rnd = (long)(get_random_int() % (1<<(23-PAGE_SHIFT)));
+       else
+               rnd = (long)(get_random_int() % (1<<(30-PAGE_SHIFT)));
+
+       return rnd << PAGE_SHIFT;
+}
+
+unsigned long arch_randomize_brk(struct mm_struct *mm)
+{
+       unsigned long base = mm->brk;
+       unsigned long ret;
+
+#ifdef CONFIG_PPC_STD_MMU_64
+       /*
+        * If we are using 1TB segments and we are allowed to randomise
+        * the heap, we can put it above 1TB so it is backed by a 1TB
+        * segment. Otherwise the heap will be in the bottom 1TB
+        * which always uses 256MB segments and this may result in a
+        * performance penalty.
+        */
+       if (!is_32bit_task() && (mmu_highuser_ssize == MMU_SEGSIZE_1T))
+               base = max_t(unsigned long, mm->brk, 1UL << SID_SHIFT_1T);
+#endif
+
+       ret = PAGE_ALIGN(base + brk_rnd());
+
+       if (ret < mm->brk)
+               return mm->brk;
+
+       return ret;
+}
+
+unsigned long randomize_et_dyn(unsigned long base)
+{
+       unsigned long ret = PAGE_ALIGN(base + brk_rnd());
+
+       if (ret < base)
+               return base;
+
+       return ret;
 }
-EXPORT_SYMBOL(get_wchan);