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linux/arch/powerpc/kernel/process.c
Kees Cook 42a20f86dc 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: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Geert 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
2021-10-15 11:25:14 +02:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Derived from "arch/i386/kernel/process.c"
* Copyright (C) 1995 Linus Torvalds
*
* Updated and modified by Cort Dougan (cort@cs.nmt.edu) and
* Paul Mackerras (paulus@cs.anu.edu.au)
*
* PowerPC version
* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
*/
#include <linux/errno.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/smp.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/elf.h>
#include <linux/prctl.h>
#include <linux/init_task.h>
#include <linux/export.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 <linux/hw_breakpoint.h>
#include <linux/uaccess.h>
#include <linux/elf-randomize.h>
#include <linux/pkeys.h>
#include <linux/seq_buf.h>
#include <asm/interrupt.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/mmu.h>
#include <asm/prom.h>
#include <asm/machdep.h>
#include <asm/time.h>
#include <asm/runlatch.h>
#include <asm/syscalls.h>
#include <asm/switch_to.h>
#include <asm/tm.h>
#include <asm/debug.h>
#ifdef CONFIG_PPC64
#include <asm/firmware.h>
#include <asm/hw_irq.h>
#endif
#include <asm/code-patching.h>
#include <asm/exec.h>
#include <asm/livepatch.h>
#include <asm/cpu_has_feature.h>
#include <asm/asm-prototypes.h>
#include <asm/stacktrace.h>
#include <asm/hw_breakpoint.h>
#include <linux/kprobes.h>
#include <linux/kdebug.h>
/* Transactional Memory debug */
#ifdef TM_DEBUG_SW
#define TM_DEBUG(x...) printk(KERN_INFO x)
#else
#define TM_DEBUG(x...) do { } while(0)
#endif
extern unsigned long _get_SP(void);
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
/*
* Are we running in "Suspend disabled" mode? If so we have to block any
* sigreturn that would get us into suspended state, and we also warn in some
* other paths that we should never reach with suspend disabled.
*/
bool tm_suspend_disabled __ro_after_init = false;
static void check_if_tm_restore_required(struct task_struct *tsk)
{
/*
* If we are saving the current thread's registers, and the
* thread is in a transactional state, set the TIF_RESTORE_TM
* bit so that we know to restore the registers before
* returning to userspace.
*/
if (tsk == current && tsk->thread.regs &&
MSR_TM_ACTIVE(tsk->thread.regs->msr) &&
!test_thread_flag(TIF_RESTORE_TM)) {
regs_set_return_msr(&tsk->thread.ckpt_regs,
tsk->thread.regs->msr);
set_thread_flag(TIF_RESTORE_TM);
}
}
#else
static inline void check_if_tm_restore_required(struct task_struct *tsk) { }
#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
bool strict_msr_control;
EXPORT_SYMBOL(strict_msr_control);
static int __init enable_strict_msr_control(char *str)
{
strict_msr_control = true;
pr_info("Enabling strict facility control\n");
return 0;
}
early_param("ppc_strict_facility_enable", enable_strict_msr_control);
/* notrace because it's called by restore_math */
unsigned long notrace msr_check_and_set(unsigned long bits)
{
unsigned long oldmsr = mfmsr();
unsigned long newmsr;
newmsr = oldmsr | bits;
if (cpu_has_feature(CPU_FTR_VSX) && (bits & MSR_FP))
newmsr |= MSR_VSX;
if (oldmsr != newmsr)
mtmsr_isync(newmsr);
return newmsr;
}
EXPORT_SYMBOL_GPL(msr_check_and_set);
/* notrace because it's called by restore_math */
void notrace __msr_check_and_clear(unsigned long bits)
{
unsigned long oldmsr = mfmsr();
unsigned long newmsr;
newmsr = oldmsr & ~bits;
if (cpu_has_feature(CPU_FTR_VSX) && (bits & MSR_FP))
newmsr &= ~MSR_VSX;
if (oldmsr != newmsr)
mtmsr_isync(newmsr);
}
EXPORT_SYMBOL(__msr_check_and_clear);
#ifdef CONFIG_PPC_FPU
static void __giveup_fpu(struct task_struct *tsk)
{
unsigned long msr;
save_fpu(tsk);
msr = tsk->thread.regs->msr;
msr &= ~(MSR_FP|MSR_FE0|MSR_FE1);
if (cpu_has_feature(CPU_FTR_VSX))
msr &= ~MSR_VSX;
regs_set_return_msr(tsk->thread.regs, msr);
}
void giveup_fpu(struct task_struct *tsk)
{
check_if_tm_restore_required(tsk);
msr_check_and_set(MSR_FP);
__giveup_fpu(tsk);
msr_check_and_clear(MSR_FP);
}
EXPORT_SYMBOL(giveup_fpu);
/*
* Make sure the floating-point register state in the
* the thread_struct is up to date for task tsk.
*/
void flush_fp_to_thread(struct task_struct *tsk)
{
if (tsk->thread.regs) {
/*
* We need to disable preemption here because if we didn't,
* another process could get scheduled after the regs->msr
* test but before we have finished saving the FP registers
* to the thread_struct. That process could take over the
* FPU, and then when we get scheduled again we would store
* bogus values for the remaining FP registers.
*/
preempt_disable();
if (tsk->thread.regs->msr & MSR_FP) {
/*
* This should only ever be called for current or
* for a stopped child process. Since we save away
* the FP register state on context switch,
* there is something wrong if a stopped child appears
* to still have its FP state in the CPU registers.
*/
BUG_ON(tsk != current);
giveup_fpu(tsk);
}
preempt_enable();
}
}
EXPORT_SYMBOL_GPL(flush_fp_to_thread);
void enable_kernel_fp(void)
{
unsigned long cpumsr;
WARN_ON(preemptible());
cpumsr = msr_check_and_set(MSR_FP);
if (current->thread.regs && (current->thread.regs->msr & MSR_FP)) {
check_if_tm_restore_required(current);
/*
* If a thread has already been reclaimed then the
* checkpointed registers are on the CPU but have definitely
* been saved by the reclaim code. Don't need to and *cannot*
* giveup as this would save to the 'live' structure not the
* checkpointed structure.
*/
if (!MSR_TM_ACTIVE(cpumsr) &&
MSR_TM_ACTIVE(current->thread.regs->msr))
return;
__giveup_fpu(current);
}
}
EXPORT_SYMBOL(enable_kernel_fp);
#else
static inline void __giveup_fpu(struct task_struct *tsk) { }
#endif /* CONFIG_PPC_FPU */
#ifdef CONFIG_ALTIVEC
static void __giveup_altivec(struct task_struct *tsk)
{
unsigned long msr;
save_altivec(tsk);
msr = tsk->thread.regs->msr;
msr &= ~MSR_VEC;
if (cpu_has_feature(CPU_FTR_VSX))
msr &= ~MSR_VSX;
regs_set_return_msr(tsk->thread.regs, msr);
}
void giveup_altivec(struct task_struct *tsk)
{
check_if_tm_restore_required(tsk);
msr_check_and_set(MSR_VEC);
__giveup_altivec(tsk);
msr_check_and_clear(MSR_VEC);
}
EXPORT_SYMBOL(giveup_altivec);
void enable_kernel_altivec(void)
{
unsigned long cpumsr;
WARN_ON(preemptible());
cpumsr = msr_check_and_set(MSR_VEC);
if (current->thread.regs && (current->thread.regs->msr & MSR_VEC)) {
check_if_tm_restore_required(current);
/*
* If a thread has already been reclaimed then the
* checkpointed registers are on the CPU but have definitely
* been saved by the reclaim code. Don't need to and *cannot*
* giveup as this would save to the 'live' structure not the
* checkpointed structure.
*/
if (!MSR_TM_ACTIVE(cpumsr) &&
MSR_TM_ACTIVE(current->thread.regs->msr))
return;
__giveup_altivec(current);
}
}
EXPORT_SYMBOL(enable_kernel_altivec);
/*
* Make sure the VMX/Altivec register state in the
* the thread_struct is up to date for task tsk.
*/
void flush_altivec_to_thread(struct task_struct *tsk)
{
if (tsk->thread.regs) {
preempt_disable();
if (tsk->thread.regs->msr & MSR_VEC) {
BUG_ON(tsk != current);
giveup_altivec(tsk);
}
preempt_enable();
}
}
EXPORT_SYMBOL_GPL(flush_altivec_to_thread);
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_VSX
static void __giveup_vsx(struct task_struct *tsk)
{
unsigned long msr = tsk->thread.regs->msr;
/*
* We should never be ssetting MSR_VSX without also setting
* MSR_FP and MSR_VEC
*/
WARN_ON((msr & MSR_VSX) && !((msr & MSR_FP) && (msr & MSR_VEC)));
/* __giveup_fpu will clear MSR_VSX */
if (msr & MSR_FP)
__giveup_fpu(tsk);
if (msr & MSR_VEC)
__giveup_altivec(tsk);
}
static void giveup_vsx(struct task_struct *tsk)
{
check_if_tm_restore_required(tsk);
msr_check_and_set(MSR_FP|MSR_VEC|MSR_VSX);
__giveup_vsx(tsk);
msr_check_and_clear(MSR_FP|MSR_VEC|MSR_VSX);
}
void enable_kernel_vsx(void)
{
unsigned long cpumsr;
WARN_ON(preemptible());
cpumsr = msr_check_and_set(MSR_FP|MSR_VEC|MSR_VSX);
if (current->thread.regs &&
(current->thread.regs->msr & (MSR_VSX|MSR_VEC|MSR_FP))) {
check_if_tm_restore_required(current);
/*
* If a thread has already been reclaimed then the
* checkpointed registers are on the CPU but have definitely
* been saved by the reclaim code. Don't need to and *cannot*
* giveup as this would save to the 'live' structure not the
* checkpointed structure.
*/
if (!MSR_TM_ACTIVE(cpumsr) &&
MSR_TM_ACTIVE(current->thread.regs->msr))
return;
__giveup_vsx(current);
}
}
EXPORT_SYMBOL(enable_kernel_vsx);
void flush_vsx_to_thread(struct task_struct *tsk)
{
if (tsk->thread.regs) {
preempt_disable();
if (tsk->thread.regs->msr & (MSR_VSX|MSR_VEC|MSR_FP)) {
BUG_ON(tsk != current);
giveup_vsx(tsk);
}
preempt_enable();
}
}
EXPORT_SYMBOL_GPL(flush_vsx_to_thread);
#endif /* CONFIG_VSX */
#ifdef CONFIG_SPE
void giveup_spe(struct task_struct *tsk)
{
check_if_tm_restore_required(tsk);
msr_check_and_set(MSR_SPE);
__giveup_spe(tsk);
msr_check_and_clear(MSR_SPE);
}
EXPORT_SYMBOL(giveup_spe);
void enable_kernel_spe(void)
{
WARN_ON(preemptible());
msr_check_and_set(MSR_SPE);
if (current->thread.regs && (current->thread.regs->msr & MSR_SPE)) {
check_if_tm_restore_required(current);
__giveup_spe(current);
}
}
EXPORT_SYMBOL(enable_kernel_spe);
void flush_spe_to_thread(struct task_struct *tsk)
{
if (tsk->thread.regs) {
preempt_disable();
if (tsk->thread.regs->msr & MSR_SPE) {
BUG_ON(tsk != current);
tsk->thread.spefscr = mfspr(SPRN_SPEFSCR);
giveup_spe(tsk);
}
preempt_enable();
}
}
#endif /* CONFIG_SPE */
static unsigned long msr_all_available;
static int __init init_msr_all_available(void)
{
if (IS_ENABLED(CONFIG_PPC_FPU))
msr_all_available |= MSR_FP;
if (cpu_has_feature(CPU_FTR_ALTIVEC))
msr_all_available |= MSR_VEC;
if (cpu_has_feature(CPU_FTR_VSX))
msr_all_available |= MSR_VSX;
if (cpu_has_feature(CPU_FTR_SPE))
msr_all_available |= MSR_SPE;
return 0;
}
early_initcall(init_msr_all_available);
void giveup_all(struct task_struct *tsk)
{
unsigned long usermsr;
if (!tsk->thread.regs)
return;
check_if_tm_restore_required(tsk);
usermsr = tsk->thread.regs->msr;
if ((usermsr & msr_all_available) == 0)
return;
msr_check_and_set(msr_all_available);
WARN_ON((usermsr & MSR_VSX) && !((usermsr & MSR_FP) && (usermsr & MSR_VEC)));
if (usermsr & MSR_FP)
__giveup_fpu(tsk);
if (usermsr & MSR_VEC)
__giveup_altivec(tsk);
if (usermsr & MSR_SPE)
__giveup_spe(tsk);
msr_check_and_clear(msr_all_available);
}
EXPORT_SYMBOL(giveup_all);
#ifdef CONFIG_PPC_BOOK3S_64
#ifdef CONFIG_PPC_FPU
static bool should_restore_fp(void)
{
if (current->thread.load_fp) {
current->thread.load_fp++;
return true;
}
return false;
}
static void do_restore_fp(void)
{
load_fp_state(&current->thread.fp_state);
}
#else
static bool should_restore_fp(void) { return false; }
static void do_restore_fp(void) { }
#endif /* CONFIG_PPC_FPU */
#ifdef CONFIG_ALTIVEC
static bool should_restore_altivec(void)
{
if (cpu_has_feature(CPU_FTR_ALTIVEC) && (current->thread.load_vec)) {
current->thread.load_vec++;
return true;
}
return false;
}
static void do_restore_altivec(void)
{
load_vr_state(&current->thread.vr_state);
current->thread.used_vr = 1;
}
#else
static bool should_restore_altivec(void) { return false; }
static void do_restore_altivec(void) { }
#endif /* CONFIG_ALTIVEC */
static bool should_restore_vsx(void)
{
if (cpu_has_feature(CPU_FTR_VSX))
return true;
return false;
}
#ifdef CONFIG_VSX
static void do_restore_vsx(void)
{
current->thread.used_vsr = 1;
}
#else
static void do_restore_vsx(void) { }
#endif /* CONFIG_VSX */
/*
* The exception exit path calls restore_math() with interrupts hard disabled
* but the soft irq state not "reconciled". ftrace code that calls
* local_irq_save/restore causes warnings.
*
* Rather than complicate the exit path, just don't trace restore_math. This
* could be done by having ftrace entry code check for this un-reconciled
* condition where MSR[EE]=0 and PACA_IRQ_HARD_DIS is not set, and
* temporarily fix it up for the duration of the ftrace call.
*/
void notrace restore_math(struct pt_regs *regs)
{
unsigned long msr;
unsigned long new_msr = 0;
msr = regs->msr;
/*
* new_msr tracks the facilities that are to be restored. Only reload
* if the bit is not set in the user MSR (if it is set, the registers
* are live for the user thread).
*/
if ((!(msr & MSR_FP)) && should_restore_fp())
new_msr |= MSR_FP;
if ((!(msr & MSR_VEC)) && should_restore_altivec())
new_msr |= MSR_VEC;
if ((!(msr & MSR_VSX)) && should_restore_vsx()) {
if (((msr | new_msr) & (MSR_FP | MSR_VEC)) == (MSR_FP | MSR_VEC))
new_msr |= MSR_VSX;
}
if (new_msr) {
unsigned long fpexc_mode = 0;
msr_check_and_set(new_msr);
if (new_msr & MSR_FP) {
do_restore_fp();
// This also covers VSX, because VSX implies FP
fpexc_mode = current->thread.fpexc_mode;
}
if (new_msr & MSR_VEC)
do_restore_altivec();
if (new_msr & MSR_VSX)
do_restore_vsx();
msr_check_and_clear(new_msr);
regs_set_return_msr(regs, regs->msr | new_msr | fpexc_mode);
}
}
#endif /* CONFIG_PPC_BOOK3S_64 */
static void save_all(struct task_struct *tsk)
{
unsigned long usermsr;
if (!tsk->thread.regs)
return;
usermsr = tsk->thread.regs->msr;
if ((usermsr & msr_all_available) == 0)
return;
msr_check_and_set(msr_all_available);
WARN_ON((usermsr & MSR_VSX) && !((usermsr & MSR_FP) && (usermsr & MSR_VEC)));
if (usermsr & MSR_FP)
save_fpu(tsk);
if (usermsr & MSR_VEC)
save_altivec(tsk);
if (usermsr & MSR_SPE)
__giveup_spe(tsk);
msr_check_and_clear(msr_all_available);
}
void flush_all_to_thread(struct task_struct *tsk)
{
if (tsk->thread.regs) {
preempt_disable();
BUG_ON(tsk != current);
#ifdef CONFIG_SPE
if (tsk->thread.regs->msr & MSR_SPE)
tsk->thread.spefscr = mfspr(SPRN_SPEFSCR);
#endif
save_all(tsk);
preempt_enable();
}
}
EXPORT_SYMBOL(flush_all_to_thread);
#ifdef CONFIG_PPC_ADV_DEBUG_REGS
void do_send_trap(struct pt_regs *regs, unsigned long address,
unsigned long error_code, int breakpt)
{
current->thread.trap_nr = TRAP_HWBKPT;
if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code,
11, SIGSEGV) == NOTIFY_STOP)
return;
/* Deliver the signal to userspace */
force_sig_ptrace_errno_trap(breakpt, /* breakpoint or watchpoint id */
(void __user *)address);
}
#else /* !CONFIG_PPC_ADV_DEBUG_REGS */
static void do_break_handler(struct pt_regs *regs)
{
struct arch_hw_breakpoint null_brk = {0};
struct arch_hw_breakpoint *info;
struct ppc_inst instr = ppc_inst(0);
int type = 0;
int size = 0;
unsigned long ea;
int i;
/*
* If underneath hw supports only one watchpoint, we know it
* caused exception. 8xx also falls into this category.
*/
if (nr_wp_slots() == 1) {
__set_breakpoint(0, &null_brk);
current->thread.hw_brk[0] = null_brk;
current->thread.hw_brk[0].flags |= HW_BRK_FLAG_DISABLED;
return;
}
/* Otherwise findout which DAWR caused exception and disable it. */
wp_get_instr_detail(regs, &instr, &type, &size, &ea);
for (i = 0; i < nr_wp_slots(); i++) {
info = &current->thread.hw_brk[i];
if (!info->address)
continue;
if (wp_check_constraints(regs, instr, ea, type, size, info)) {
__set_breakpoint(i, &null_brk);
current->thread.hw_brk[i] = null_brk;
current->thread.hw_brk[i].flags |= HW_BRK_FLAG_DISABLED;
}
}
}
DEFINE_INTERRUPT_HANDLER(do_break)
{
current->thread.trap_nr = TRAP_HWBKPT;
if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, regs->dsisr,
11, SIGSEGV) == NOTIFY_STOP)
return;
if (debugger_break_match(regs))
return;
/*
* We reach here only when watchpoint exception is generated by ptrace
* event (or hw is buggy!). Now if CONFIG_HAVE_HW_BREAKPOINT is set,
* watchpoint is already handled by hw_breakpoint_handler() so we don't
* have to do anything. But when CONFIG_HAVE_HW_BREAKPOINT is not set,
* we need to manually handle the watchpoint here.
*/
if (!IS_ENABLED(CONFIG_HAVE_HW_BREAKPOINT))
do_break_handler(regs);
/* Deliver the signal to userspace */
force_sig_fault(SIGTRAP, TRAP_HWBKPT, (void __user *)regs->dar);
}
#endif /* CONFIG_PPC_ADV_DEBUG_REGS */
static DEFINE_PER_CPU(struct arch_hw_breakpoint, current_brk[HBP_NUM_MAX]);
#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->debug.iac1 = thread->debug.iac2 = 0;
#if CONFIG_PPC_ADV_DEBUG_IACS > 2
thread->debug.iac3 = thread->debug.iac4 = 0;
#endif
thread->debug.dac1 = thread->debug.dac2 = 0;
#if CONFIG_PPC_ADV_DEBUG_DVCS > 0
thread->debug.dvc1 = thread->debug.dvc2 = 0;
#endif
thread->debug.dbcr0 = 0;
#ifdef CONFIG_BOOKE
/*
* Force User/Supervisor bits to b11 (user-only MSR[PR]=1)
*/
thread->debug.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->debug.dbcr2 = DBCR2_DAC1US | DBCR2_DAC2US;
#else
thread->debug.dbcr1 = 0;
#endif
}
static void prime_debug_regs(struct debug_reg *debug)
{
/*
* We could have inherited MSR_DE from userspace, since
* it doesn't get cleared on exception entry. Make sure
* MSR_DE is clear before we enable any debug events.
*/
mtmsr(mfmsr() & ~MSR_DE);
mtspr(SPRN_IAC1, debug->iac1);
mtspr(SPRN_IAC2, debug->iac2);
#if CONFIG_PPC_ADV_DEBUG_IACS > 2
mtspr(SPRN_IAC3, debug->iac3);
mtspr(SPRN_IAC4, debug->iac4);
#endif
mtspr(SPRN_DAC1, debug->dac1);
mtspr(SPRN_DAC2, debug->dac2);
#if CONFIG_PPC_ADV_DEBUG_DVCS > 0
mtspr(SPRN_DVC1, debug->dvc1);
mtspr(SPRN_DVC2, debug->dvc2);
#endif
mtspr(SPRN_DBCR0, debug->dbcr0);
mtspr(SPRN_DBCR1, debug->dbcr1);
#ifdef CONFIG_BOOKE
mtspr(SPRN_DBCR2, debug->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.
*/
void switch_booke_debug_regs(struct debug_reg *new_debug)
{
if ((current->thread.debug.dbcr0 & DBCR0_IDM)
|| (new_debug->dbcr0 & DBCR0_IDM))
prime_debug_regs(new_debug);
}
EXPORT_SYMBOL_GPL(switch_booke_debug_regs);
#else /* !CONFIG_PPC_ADV_DEBUG_REGS */
#ifndef CONFIG_HAVE_HW_BREAKPOINT
static void set_breakpoint(int i, struct arch_hw_breakpoint *brk)
{
preempt_disable();
__set_breakpoint(i, brk);
preempt_enable();
}
static void set_debug_reg_defaults(struct thread_struct *thread)
{
int i;
struct arch_hw_breakpoint null_brk = {0};
for (i = 0; i < nr_wp_slots(); i++) {
thread->hw_brk[i] = null_brk;
if (ppc_breakpoint_available())
set_breakpoint(i, &thread->hw_brk[i]);
}
}
static inline bool hw_brk_match(struct arch_hw_breakpoint *a,
struct arch_hw_breakpoint *b)
{
if (a->address != b->address)
return false;
if (a->type != b->type)
return false;
if (a->len != b->len)
return false;
/* no need to check hw_len. it's calculated from address and len */
return true;
}
static void switch_hw_breakpoint(struct task_struct *new)
{
int i;
for (i = 0; i < nr_wp_slots(); i++) {
if (likely(hw_brk_match(this_cpu_ptr(&current_brk[i]),
&new->thread.hw_brk[i])))
continue;
__set_breakpoint(i, &new->thread.hw_brk[i]);
}
}
#endif /* !CONFIG_HAVE_HW_BREAKPOINT */
#endif /* CONFIG_PPC_ADV_DEBUG_REGS */
static inline int set_dabr(struct arch_hw_breakpoint *brk)
{
unsigned long dabr, dabrx;
dabr = brk->address | (brk->type & HW_BRK_TYPE_DABR);
dabrx = ((brk->type >> 3) & 0x7);
if (ppc_md.set_dabr)
return ppc_md.set_dabr(dabr, dabrx);
if (IS_ENABLED(CONFIG_PPC_ADV_DEBUG_REGS)) {
mtspr(SPRN_DAC1, dabr);
if (IS_ENABLED(CONFIG_PPC_47x))
isync();
return 0;
} else if (IS_ENABLED(CONFIG_PPC_BOOK3S)) {
mtspr(SPRN_DABR, dabr);
if (cpu_has_feature(CPU_FTR_DABRX))
mtspr(SPRN_DABRX, dabrx);
return 0;
} else {
return -EINVAL;
}
}
static inline int set_breakpoint_8xx(struct arch_hw_breakpoint *brk)
{
unsigned long lctrl1 = LCTRL1_CTE_GT | LCTRL1_CTF_LT | LCTRL1_CRWE_RW |
LCTRL1_CRWF_RW;
unsigned long lctrl2 = LCTRL2_LW0EN | LCTRL2_LW0LADC | LCTRL2_SLW0EN;
unsigned long start_addr = ALIGN_DOWN(brk->address, HW_BREAKPOINT_SIZE);
unsigned long end_addr = ALIGN(brk->address + brk->len, HW_BREAKPOINT_SIZE);
if (start_addr == 0)
lctrl2 |= LCTRL2_LW0LA_F;
else if (end_addr == 0)
lctrl2 |= LCTRL2_LW0LA_E;
else
lctrl2 |= LCTRL2_LW0LA_EandF;
mtspr(SPRN_LCTRL2, 0);
if ((brk->type & HW_BRK_TYPE_RDWR) == 0)
return 0;
if ((brk->type & HW_BRK_TYPE_RDWR) == HW_BRK_TYPE_READ)
lctrl1 |= LCTRL1_CRWE_RO | LCTRL1_CRWF_RO;
if ((brk->type & HW_BRK_TYPE_RDWR) == HW_BRK_TYPE_WRITE)
lctrl1 |= LCTRL1_CRWE_WO | LCTRL1_CRWF_WO;
mtspr(SPRN_CMPE, start_addr - 1);
mtspr(SPRN_CMPF, end_addr);
mtspr(SPRN_LCTRL1, lctrl1);
mtspr(SPRN_LCTRL2, lctrl2);
return 0;
}
void __set_breakpoint(int nr, struct arch_hw_breakpoint *brk)
{
memcpy(this_cpu_ptr(&current_brk[nr]), brk, sizeof(*brk));
if (dawr_enabled())
// Power8 or later
set_dawr(nr, brk);
else if (IS_ENABLED(CONFIG_PPC_8xx))
set_breakpoint_8xx(brk);
else if (!cpu_has_feature(CPU_FTR_ARCH_207S))
// Power7 or earlier
set_dabr(brk);
else
// Shouldn't happen due to higher level checks
WARN_ON_ONCE(1);
}
/* Check if we have DAWR or DABR hardware */
bool ppc_breakpoint_available(void)
{
if (dawr_enabled())
return true; /* POWER8 DAWR or POWER9 forced DAWR */
if (cpu_has_feature(CPU_FTR_ARCH_207S))
return false; /* POWER9 with DAWR disabled */
/* DABR: Everything but POWER8 and POWER9 */
return true;
}
EXPORT_SYMBOL_GPL(ppc_breakpoint_available);
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
static inline bool tm_enabled(struct task_struct *tsk)
{
return tsk && tsk->thread.regs && (tsk->thread.regs->msr & MSR_TM);
}
static void tm_reclaim_thread(struct thread_struct *thr, uint8_t cause)
{
/*
* Use the current MSR TM suspended bit to track if we have
* checkpointed state outstanding.
* On signal delivery, we'd normally reclaim the checkpointed
* state to obtain stack pointer (see:get_tm_stackpointer()).
* This will then directly return to userspace without going
* through __switch_to(). However, if the stack frame is bad,
* we need to exit this thread which calls __switch_to() which
* will again attempt to reclaim the already saved tm state.
* Hence we need to check that we've not already reclaimed
* this state.
* We do this using the current MSR, rather tracking it in
* some specific thread_struct bit, as it has the additional
* benefit of checking for a potential TM bad thing exception.
*/
if (!MSR_TM_SUSPENDED(mfmsr()))
return;
giveup_all(container_of(thr, struct task_struct, thread));
tm_reclaim(thr, cause);
/*
* If we are in a transaction and FP is off then we can't have
* used FP inside that transaction. Hence the checkpointed
* state is the same as the live state. We need to copy the
* live state to the checkpointed state so that when the
* transaction is restored, the checkpointed state is correct
* and the aborted transaction sees the correct state. We use
* ckpt_regs.msr here as that's what tm_reclaim will use to
* determine if it's going to write the checkpointed state or
* not. So either this will write the checkpointed registers,
* or reclaim will. Similarly for VMX.
*/
if ((thr->ckpt_regs.msr & MSR_FP) == 0)
memcpy(&thr->ckfp_state, &thr->fp_state,
sizeof(struct thread_fp_state));
if ((thr->ckpt_regs.msr & MSR_VEC) == 0)
memcpy(&thr->ckvr_state, &thr->vr_state,
sizeof(struct thread_vr_state));
}
void tm_reclaim_current(uint8_t cause)
{
tm_enable();
tm_reclaim_thread(&current->thread, cause);
}
static inline void tm_reclaim_task(struct task_struct *tsk)
{
/* We have to work out if we're switching from/to a task that's in the
* middle of a transaction.
*
* In switching we need to maintain a 2nd register state as
* oldtask->thread.ckpt_regs. We tm_reclaim(oldproc); this saves the
* checkpointed (tbegin) state in ckpt_regs, ckfp_state and
* ckvr_state
*
* We also context switch (save) TFHAR/TEXASR/TFIAR in here.
*/
struct thread_struct *thr = &tsk->thread;
if (!thr->regs)
return;
if (!MSR_TM_ACTIVE(thr->regs->msr))
goto out_and_saveregs;
WARN_ON(tm_suspend_disabled);
TM_DEBUG("--- tm_reclaim on pid %d (NIP=%lx, "
"ccr=%lx, msr=%lx, trap=%lx)\n",
tsk->pid, thr->regs->nip,
thr->regs->ccr, thr->regs->msr,
thr->regs->trap);
tm_reclaim_thread(thr, TM_CAUSE_RESCHED);
TM_DEBUG("--- tm_reclaim on pid %d complete\n",
tsk->pid);
out_and_saveregs:
/* Always save the regs here, even if a transaction's not active.
* This context-switches a thread's TM info SPRs. We do it here to
* be consistent with the restore path (in recheckpoint) which
* cannot happen later in _switch().
*/
tm_save_sprs(thr);
}
extern void __tm_recheckpoint(struct thread_struct *thread);
void tm_recheckpoint(struct thread_struct *thread)
{
unsigned long flags;
if (!(thread->regs->msr & MSR_TM))
return;
/* We really can't be interrupted here as the TEXASR registers can't
* change and later in the trecheckpoint code, we have a userspace R1.
* So let's hard disable over this region.
*/
local_irq_save(flags);
hard_irq_disable();
/* The TM SPRs are restored here, so that TEXASR.FS can be set
* before the trecheckpoint and no explosion occurs.
*/
tm_restore_sprs(thread);
__tm_recheckpoint(thread);
local_irq_restore(flags);
}
static inline void tm_recheckpoint_new_task(struct task_struct *new)
{
if (!cpu_has_feature(CPU_FTR_TM))
return;
/* Recheckpoint the registers of the thread we're about to switch to.
*
* If the task was using FP, we non-lazily reload both the original and
* the speculative FP register states. This is because the kernel
* doesn't see if/when a TM rollback occurs, so if we take an FP
* unavailable later, we are unable to determine which set of FP regs
* need to be restored.
*/
if (!tm_enabled(new))
return;
if (!MSR_TM_ACTIVE(new->thread.regs->msr)){
tm_restore_sprs(&new->thread);
return;
}
/* Recheckpoint to restore original checkpointed register state. */
TM_DEBUG("*** tm_recheckpoint of pid %d (new->msr 0x%lx)\n",
new->pid, new->thread.regs->msr);
tm_recheckpoint(&new->thread);
/*
* The checkpointed state has been restored but the live state has
* not, ensure all the math functionality is turned off to trigger
* restore_math() to reload.
*/
new->thread.regs->msr &= ~(MSR_FP | MSR_VEC | MSR_VSX);
TM_DEBUG("*** tm_recheckpoint of pid %d complete "
"(kernel msr 0x%lx)\n",
new->pid, mfmsr());
}
static inline void __switch_to_tm(struct task_struct *prev,
struct task_struct *new)
{
if (cpu_has_feature(CPU_FTR_TM)) {
if (tm_enabled(prev) || tm_enabled(new))
tm_enable();
if (tm_enabled(prev)) {
prev->thread.load_tm++;
tm_reclaim_task(prev);
if (!MSR_TM_ACTIVE(prev->thread.regs->msr) && prev->thread.load_tm == 0)
prev->thread.regs->msr &= ~MSR_TM;
}
tm_recheckpoint_new_task(new);
}
}
/*
* This is called if we are on the way out to userspace and the
* TIF_RESTORE_TM flag is set. It checks if we need to reload
* FP and/or vector state and does so if necessary.
* If userspace is inside a transaction (whether active or
* suspended) and FP/VMX/VSX instructions have ever been enabled
* inside that transaction, then we have to keep them enabled
* and keep the FP/VMX/VSX state loaded while ever the transaction
* continues. The reason is that if we didn't, and subsequently
* got a FP/VMX/VSX unavailable interrupt inside a transaction,
* we don't know whether it's the same transaction, and thus we
* don't know which of the checkpointed state and the transactional
* state to use.
*/
void restore_tm_state(struct pt_regs *regs)
{
unsigned long msr_diff;
/*
* This is the only moment we should clear TIF_RESTORE_TM as
* it is here that ckpt_regs.msr and pt_regs.msr become the same
* again, anything else could lead to an incorrect ckpt_msr being
* saved and therefore incorrect signal contexts.
*/
clear_thread_flag(TIF_RESTORE_TM);
if (!MSR_TM_ACTIVE(regs->msr))
return;
msr_diff = current->thread.ckpt_regs.msr & ~regs->msr;
msr_diff &= MSR_FP | MSR_VEC | MSR_VSX;
/* Ensure that restore_math() will restore */
if (msr_diff & MSR_FP)
current->thread.load_fp = 1;
#ifdef CONFIG_ALTIVEC
if (cpu_has_feature(CPU_FTR_ALTIVEC) && msr_diff & MSR_VEC)
current->thread.load_vec = 1;
#endif
restore_math(regs);
regs_set_return_msr(regs, regs->msr | msr_diff);
}
#else /* !CONFIG_PPC_TRANSACTIONAL_MEM */
#define tm_recheckpoint_new_task(new)
#define __switch_to_tm(prev, new)
void tm_reclaim_current(uint8_t cause) {}
#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
static inline void save_sprs(struct thread_struct *t)
{
#ifdef CONFIG_ALTIVEC
if (cpu_has_feature(CPU_FTR_ALTIVEC))
t->vrsave = mfspr(SPRN_VRSAVE);
#endif
#ifdef CONFIG_SPE
if (cpu_has_feature(CPU_FTR_SPE))
t->spefscr = mfspr(SPRN_SPEFSCR);
#endif
#ifdef CONFIG_PPC_BOOK3S_64
if (cpu_has_feature(CPU_FTR_DSCR))
t->dscr = mfspr(SPRN_DSCR);
if (cpu_has_feature(CPU_FTR_ARCH_207S)) {
t->bescr = mfspr(SPRN_BESCR);
t->ebbhr = mfspr(SPRN_EBBHR);
t->ebbrr = mfspr(SPRN_EBBRR);
t->fscr = mfspr(SPRN_FSCR);
/*
* Note that the TAR is not available for use in the kernel.
* (To provide this, the TAR should be backed up/restored on
* exception entry/exit instead, and be in pt_regs. FIXME,
* this should be in pt_regs anyway (for debug).)
*/
t->tar = mfspr(SPRN_TAR);
}
#endif
}
static inline void restore_sprs(struct thread_struct *old_thread,
struct thread_struct *new_thread)
{
#ifdef CONFIG_ALTIVEC
if (cpu_has_feature(CPU_FTR_ALTIVEC) &&
old_thread->vrsave != new_thread->vrsave)
mtspr(SPRN_VRSAVE, new_thread->vrsave);
#endif
#ifdef CONFIG_SPE
if (cpu_has_feature(CPU_FTR_SPE) &&
old_thread->spefscr != new_thread->spefscr)
mtspr(SPRN_SPEFSCR, new_thread->spefscr);
#endif
#ifdef CONFIG_PPC_BOOK3S_64
if (cpu_has_feature(CPU_FTR_DSCR)) {
u64 dscr = get_paca()->dscr_default;
if (new_thread->dscr_inherit)
dscr = new_thread->dscr;
if (old_thread->dscr != dscr)
mtspr(SPRN_DSCR, dscr);
}
if (cpu_has_feature(CPU_FTR_ARCH_207S)) {
if (old_thread->bescr != new_thread->bescr)
mtspr(SPRN_BESCR, new_thread->bescr);
if (old_thread->ebbhr != new_thread->ebbhr)
mtspr(SPRN_EBBHR, new_thread->ebbhr);
if (old_thread->ebbrr != new_thread->ebbrr)
mtspr(SPRN_EBBRR, new_thread->ebbrr);
if (old_thread->fscr != new_thread->fscr)
mtspr(SPRN_FSCR, new_thread->fscr);
if (old_thread->tar != new_thread->tar)
mtspr(SPRN_TAR, new_thread->tar);
}
if (cpu_has_feature(CPU_FTR_P9_TIDR) &&
old_thread->tidr != new_thread->tidr)
mtspr(SPRN_TIDR, new_thread->tidr);
#endif
}
struct task_struct *__switch_to(struct task_struct *prev,
struct task_struct *new)
{
struct thread_struct *new_thread, *old_thread;
struct task_struct *last;
#ifdef CONFIG_PPC_BOOK3S_64
struct ppc64_tlb_batch *batch;
#endif
new_thread = &new->thread;
old_thread = &current->thread;
WARN_ON(!irqs_disabled());
#ifdef CONFIG_PPC_BOOK3S_64
batch = this_cpu_ptr(&ppc64_tlb_batch);
if (batch->active) {
current_thread_info()->local_flags |= _TLF_LAZY_MMU;
if (batch->index)
__flush_tlb_pending(batch);
batch->active = 0;
}
/*
* On POWER9 the copy-paste buffer can only paste into
* foreign real addresses, so unprivileged processes can not
* see the data or use it in any way unless they have
* foreign real mappings. If the new process has the foreign
* real address mappings, we must issue a cp_abort to clear
* any state and prevent snooping, corruption or a covert
* channel. ISA v3.1 supports paste into local memory.
*/
if (new->mm && (cpu_has_feature(CPU_FTR_ARCH_31) ||
atomic_read(&new->mm->context.vas_windows)))
asm volatile(PPC_CP_ABORT);
#endif /* CONFIG_PPC_BOOK3S_64 */
#ifdef CONFIG_PPC_ADV_DEBUG_REGS
switch_booke_debug_regs(&new->thread.debug);
#else
/*
* For PPC_BOOK3S_64, we use the hw-breakpoint interfaces that would
* schedule DABR
*/
#ifndef CONFIG_HAVE_HW_BREAKPOINT
switch_hw_breakpoint(new);
#endif /* CONFIG_HAVE_HW_BREAKPOINT */
#endif
/*
* We need to save SPRs before treclaim/trecheckpoint as these will
* change a number of them.
*/
save_sprs(&prev->thread);
/* Save FPU, Altivec, VSX and SPE state */
giveup_all(prev);
__switch_to_tm(prev, new);
if (!radix_enabled()) {
/*
* 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();
}
/*
* Call restore_sprs() and set_return_regs_changed() before calling
* _switch(). If we move it after _switch() then we miss out on calling
* it for new tasks. The reason for this is we manually create a stack
* frame for new tasks that directly returns through ret_from_fork() or
* ret_from_kernel_thread(). See copy_thread() for details.
*/
restore_sprs(old_thread, new_thread);
set_return_regs_changed(); /* _switch changes stack (and regs) */
#ifdef CONFIG_PPC32
kuap_assert_locked();
#endif
last = _switch(old_thread, new_thread);
/*
* Nothing after _switch will be run for newly created tasks,
* because they switch directly to ret_from_fork/ret_from_kernel_thread
* etc. Code added here should have a comment explaining why that is
* okay.
*/
#ifdef CONFIG_PPC_BOOK3S_64
/*
* This applies to a process that was context switched while inside
* arch_enter_lazy_mmu_mode(), to re-activate the batch that was
* deactivated above, before _switch(). This will never be the case
* for new tasks.
*/
if (current_thread_info()->local_flags & _TLF_LAZY_MMU) {
current_thread_info()->local_flags &= ~_TLF_LAZY_MMU;
batch = this_cpu_ptr(&ppc64_tlb_batch);
batch->active = 1;
}
/*
* Math facilities are masked out of the child MSR in copy_thread.
* A new task does not need to restore_math because it will
* demand fault them.
*/
if (current->thread.regs)
restore_math(current->thread.regs);
#endif /* CONFIG_PPC_BOOK3S_64 */
return last;
}
#define NR_INSN_TO_PRINT 16
static void show_instructions(struct pt_regs *regs)
{
int i;
unsigned long nip = regs->nip;
unsigned long pc = regs->nip - (NR_INSN_TO_PRINT * 3 / 4 * sizeof(int));
printk("Instruction dump:");
/*
* If we were executing with the MMU off for instructions, adjust pc
* rather than printing XXXXXXXX.
*/
if (!IS_ENABLED(CONFIG_BOOKE) && !(regs->msr & MSR_IR)) {
pc = (unsigned long)phys_to_virt(pc);
nip = (unsigned long)phys_to_virt(regs->nip);
}
for (i = 0; i < NR_INSN_TO_PRINT; i++) {
int instr;
if (!(i % 8))
pr_cont("\n");
if (!__kernel_text_address(pc) ||
get_kernel_nofault(instr, (const void *)pc)) {
pr_cont("XXXXXXXX ");
} else {
if (nip == pc)
pr_cont("<%08x> ", instr);
else
pr_cont("%08x ", instr);
}
pc += sizeof(int);
}
pr_cont("\n");
}
void show_user_instructions(struct pt_regs *regs)
{
unsigned long pc;
int n = NR_INSN_TO_PRINT;
struct seq_buf s;
char buf[96]; /* enough for 8 times 9 + 2 chars */
pc = regs->nip - (NR_INSN_TO_PRINT * 3 / 4 * sizeof(int));
seq_buf_init(&s, buf, sizeof(buf));
while (n) {
int i;
seq_buf_clear(&s);
for (i = 0; i < 8 && n; i++, n--, pc += sizeof(int)) {
int instr;
if (copy_from_user_nofault(&instr, (void __user *)pc,
sizeof(instr))) {
seq_buf_printf(&s, "XXXXXXXX ");
continue;
}
seq_buf_printf(&s, regs->nip == pc ? "<%08x> " : "%08x ", instr);
}
if (!seq_buf_has_overflowed(&s))
pr_info("%s[%d]: code: %s\n", current->comm,
current->pid, s.buffer);
}
}
struct regbit {
unsigned long bit;
const char *name;
};
static struct regbit msr_bits[] = {
#if defined(CONFIG_PPC64) && !defined(CONFIG_BOOKE)
{MSR_SF, "SF"},
{MSR_HV, "HV"},
#endif
{MSR_VEC, "VEC"},
{MSR_VSX, "VSX"},
#ifdef CONFIG_BOOKE
{MSR_CE, "CE"},
#endif
{MSR_EE, "EE"},
{MSR_PR, "PR"},
{MSR_FP, "FP"},
{MSR_ME, "ME"},
#ifdef CONFIG_BOOKE
{MSR_DE, "DE"},
#else
{MSR_SE, "SE"},
{MSR_BE, "BE"},
#endif
{MSR_IR, "IR"},
{MSR_DR, "DR"},
{MSR_PMM, "PMM"},
#ifndef CONFIG_BOOKE
{MSR_RI, "RI"},
{MSR_LE, "LE"},
#endif
{0, NULL}
};
static void print_bits(unsigned long val, struct regbit *bits, const char *sep)
{
const char *s = "";
for (; bits->bit; ++bits)
if (val & bits->bit) {
pr_cont("%s%s", s, bits->name);
s = sep;
}
}
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
static struct regbit msr_tm_bits[] = {
{MSR_TS_T, "T"},
{MSR_TS_S, "S"},
{MSR_TM, "E"},
{0, NULL}
};
static void print_tm_bits(unsigned long val)
{
/*
* This only prints something if at least one of the TM bit is set.
* Inside the TM[], the output means:
* E: Enabled (bit 32)
* S: Suspended (bit 33)
* T: Transactional (bit 34)
*/
if (val & (MSR_TM | MSR_TS_S | MSR_TS_T)) {
pr_cont(",TM[");
print_bits(val, msr_tm_bits, "");
pr_cont("]");
}
}
#else
static void print_tm_bits(unsigned long val) {}
#endif
static void print_msr_bits(unsigned long val)
{
pr_cont("<");
print_bits(val, msr_bits, ",");
print_tm_bits(val);
pr_cont(">");
}
#ifdef CONFIG_PPC64
#define REG "%016lx"
#define REGS_PER_LINE 4
#else
#define REG "%08lx"
#define REGS_PER_LINE 8
#endif
static void __show_regs(struct pt_regs *regs)
{
int i, trap;
printk("NIP: "REG" LR: "REG" CTR: "REG"\n",
regs->nip, regs->link, regs->ctr);
printk("REGS: %px TRAP: %04lx %s (%s)\n",
regs, regs->trap, print_tainted(), init_utsname()->release);
printk("MSR: "REG" ", regs->msr);
print_msr_bits(regs->msr);
pr_cont(" CR: %08lx XER: %08lx\n", regs->ccr, regs->xer);
trap = TRAP(regs);
if (!trap_is_syscall(regs) && cpu_has_feature(CPU_FTR_CFAR))
pr_cont("CFAR: "REG" ", regs->orig_gpr3);
if (trap == INTERRUPT_MACHINE_CHECK ||
trap == INTERRUPT_DATA_STORAGE ||
trap == INTERRUPT_ALIGNMENT) {
if (IS_ENABLED(CONFIG_4xx) || IS_ENABLED(CONFIG_BOOKE))
pr_cont("DEAR: "REG" ESR: "REG" ", regs->dear, regs->esr);
else
pr_cont("DAR: "REG" DSISR: %08lx ", regs->dar, regs->dsisr);
}
#ifdef CONFIG_PPC64
pr_cont("IRQMASK: %lx ", regs->softe);
#endif
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
if (MSR_TM_ACTIVE(regs->msr))
pr_cont("\nPACATMSCRATCH: %016llx ", get_paca()->tm_scratch);
#endif
for (i = 0; i < 32; i++) {
if ((i % REGS_PER_LINE) == 0)
pr_cont("\nGPR%02d: ", i);
pr_cont(REG " ", regs->gpr[i]);
}
pr_cont("\n");
/*
* Lookup NIP late so we have the best change of getting the
* above info out without failing
*/
if (IS_ENABLED(CONFIG_KALLSYMS)) {
printk("NIP ["REG"] %pS\n", regs->nip, (void *)regs->nip);
printk("LR ["REG"] %pS\n", regs->link, (void *)regs->link);
}
}
void show_regs(struct pt_regs *regs)
{
show_regs_print_info(KERN_DEFAULT);
__show_regs(regs);
show_stack(current, (unsigned long *) regs->gpr[1], KERN_DEFAULT);
if (!user_mode(regs))
show_instructions(regs);
}
void flush_thread(void)
{
#ifdef CONFIG_HAVE_HW_BREAKPOINT
flush_ptrace_hw_breakpoint(current);
#else /* CONFIG_HAVE_HW_BREAKPOINT */
set_debug_reg_defaults(&current->thread);
#endif /* CONFIG_HAVE_HW_BREAKPOINT */
}
void arch_setup_new_exec(void)
{
#ifdef CONFIG_PPC_BOOK3S_64
if (!radix_enabled())
hash__setup_new_exec();
#endif
/*
* 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;
}
#ifdef CONFIG_PPC_MEM_KEYS
current->thread.regs->amr = default_amr;
current->thread.regs->iamr = default_iamr;
#endif
}
#ifdef CONFIG_PPC64
/**
* Assign a TIDR (thread ID) for task @t and set it in the thread
* structure. For now, we only support setting TIDR for 'current' task.
*
* Since the TID value is a truncated form of it PID, it is possible
* (but unlikely) for 2 threads to have the same TID. In the unlikely event
* that 2 threads share the same TID and are waiting, one of the following
* cases will happen:
*
* 1. The correct thread is running, the wrong thread is not
* In this situation, the correct thread is woken and proceeds to pass it's
* condition check.
*
* 2. Neither threads are running
* In this situation, neither thread will be woken. When scheduled, the waiting
* threads will execute either a wait, which will return immediately, followed
* by a condition check, which will pass for the correct thread and fail
* for the wrong thread, or they will execute the condition check immediately.
*
* 3. The wrong thread is running, the correct thread is not
* The wrong thread will be woken, but will fail it's condition check and
* re-execute wait. The correct thread, when scheduled, will execute either
* it's condition check (which will pass), or wait, which returns immediately
* when called the first time after the thread is scheduled, followed by it's
* condition check (which will pass).
*
* 4. Both threads are running
* Both threads will be woken. The wrong thread will fail it's condition check
* and execute another wait, while the correct thread will pass it's condition
* check.
*
* @t: the task to set the thread ID for
*/
int set_thread_tidr(struct task_struct *t)
{
if (!cpu_has_feature(CPU_FTR_P9_TIDR))
return -EINVAL;
if (t != current)
return -EINVAL;
if (t->thread.tidr)
return 0;
t->thread.tidr = (u16)task_pid_nr(t);
mtspr(SPRN_TIDR, t->thread.tidr);
return 0;
}
EXPORT_SYMBOL_GPL(set_thread_tidr);
#endif /* CONFIG_PPC64 */
void
release_thread(struct task_struct *t)
{
}
/*
* this gets called so that we can store coprocessor state into memory and
* copy the current task into the new thread.
*/
int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
{
flush_all_to_thread(src);
/*
* Flush TM state out so we can copy it. __switch_to_tm() does this
* flush but it removes the checkpointed state from the current CPU and
* transitions the CPU out of TM mode. Hence we need to call
* tm_recheckpoint_new_task() (on the same task) to restore the
* checkpointed state back and the TM mode.
*
* Can't pass dst because it isn't ready. Doesn't matter, passing
* dst is only important for __switch_to()
*/
__switch_to_tm(src, src);
*dst = *src;
clear_task_ebb(dst);
return 0;
}
static void setup_ksp_vsid(struct task_struct *p, unsigned long sp)
{
#ifdef CONFIG_PPC_BOOK3S_64
unsigned long sp_vsid;
unsigned long llp = mmu_psize_defs[mmu_linear_psize].sllp;
if (radix_enabled())
return;
if (mmu_has_feature(MMU_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
}
/*
* Copy a thread..
*/
/*
* Copy architecture-specific thread state
*/
int copy_thread(unsigned long clone_flags, unsigned long usp,
unsigned long kthread_arg, struct task_struct *p,
unsigned long tls)
{
struct pt_regs *childregs, *kregs;
extern void ret_from_fork(void);
extern void ret_from_fork_scv(void);
extern void ret_from_kernel_thread(void);
void (*f)(void);
unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
struct thread_info *ti = task_thread_info(p);
#ifdef CONFIG_HAVE_HW_BREAKPOINT
int i;
#endif
klp_init_thread_info(p);
/* Copy registers */
sp -= sizeof(struct pt_regs);
childregs = (struct pt_regs *) sp;
if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
/* kernel thread */
memset(childregs, 0, sizeof(struct pt_regs));
childregs->gpr[1] = sp + sizeof(struct pt_regs);
/* function */
if (usp)
childregs->gpr[14] = ppc_function_entry((void *)usp);
#ifdef CONFIG_PPC64
clear_tsk_thread_flag(p, TIF_32BIT);
childregs->softe = IRQS_ENABLED;
#endif
childregs->gpr[15] = kthread_arg;
p->thread.regs = NULL; /* no user register state */
ti->flags |= _TIF_RESTOREALL;
f = ret_from_kernel_thread;
} else {
/* user thread */
struct pt_regs *regs = current_pt_regs();
*childregs = *regs;
if (usp)
childregs->gpr[1] = usp;
p->thread.regs = childregs;
/* 64s sets this in ret_from_fork */
if (!IS_ENABLED(CONFIG_PPC_BOOK3S_64))
childregs->gpr[3] = 0; /* Result from fork() */
if (clone_flags & CLONE_SETTLS) {
if (!is_32bit_task())
childregs->gpr[13] = tls;
else
childregs->gpr[2] = tls;
}
if (trap_is_scv(regs))
f = ret_from_fork_scv;
else
f = ret_from_fork;
}
childregs->msr &= ~(MSR_FP|MSR_VEC|MSR_VSX);
sp -= STACK_FRAME_OVERHEAD;
/*
* The way this works is that at some point in the future
* some task will call _switch to switch to the new task.
* That will pop off the stack frame created below and start
* the new task running at ret_from_fork. The new task will
* do some house keeping and then return from the fork or clone
* system call, using the stack frame created above.
*/
((unsigned long *)sp)[0] = 0;
sp -= sizeof(struct pt_regs);
kregs = (struct pt_regs *) sp;
sp -= STACK_FRAME_OVERHEAD;
p->thread.ksp = sp;
#ifdef CONFIG_HAVE_HW_BREAKPOINT
for (i = 0; i < nr_wp_slots(); i++)
p->thread.ptrace_bps[i] = NULL;
#endif
#ifdef CONFIG_PPC_FPU_REGS
p->thread.fp_save_area = NULL;
#endif
#ifdef CONFIG_ALTIVEC
p->thread.vr_save_area = NULL;
#endif
#if defined(CONFIG_PPC_BOOK3S_32) && defined(CONFIG_PPC_KUAP)
p->thread.kuap = KUAP_NONE;
#endif
setup_ksp_vsid(p, sp);
#ifdef CONFIG_PPC64
if (cpu_has_feature(CPU_FTR_DSCR)) {
p->thread.dscr_inherit = current->thread.dscr_inherit;
p->thread.dscr = mfspr(SPRN_DSCR);
}
if (cpu_has_feature(CPU_FTR_HAS_PPR))
childregs->ppr = DEFAULT_PPR;
p->thread.tidr = 0;
#endif
/*
* Run with the current AMR value of the kernel
*/
#ifdef CONFIG_PPC_PKEY
if (mmu_has_feature(MMU_FTR_BOOK3S_KUAP))
kregs->amr = AMR_KUAP_BLOCKED;
if (mmu_has_feature(MMU_FTR_BOOK3S_KUEP))
kregs->iamr = AMR_KUEP_BLOCKED;
#endif
kregs->nip = ppc_function_entry(f);
return 0;
}
void preload_new_slb_context(unsigned long start, unsigned long sp);
/*
* Set up a thread for executing a new program
*/
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 */
if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) && !radix_enabled())
preload_new_slb_context(start, sp);
#endif
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
/*
* Clear any transactional state, we're exec()ing. The cause is
* not important as there will never be a recheckpoint so it's not
* user visible.
*/
if (MSR_TM_SUSPENDED(mfmsr()))
tm_reclaim_current(0);
#endif
memset(regs->gpr, 0, sizeof(regs->gpr));
regs->ctr = 0;
regs->link = 0;
regs->xer = 0;
regs->ccr = 0;
regs->gpr[1] = sp;
#ifdef CONFIG_PPC32
regs->mq = 0;
regs->nip = start;
regs->msr = MSR_USER;
#else
if (!is_32bit_task()) {
unsigned long entry;
if (is_elf2_task()) {
/* Look ma, no function descriptors! */
entry = start;
/*
* Ulrich says:
* The latest iteration of the ABI requires that when
* calling a function (at its global entry point),
* the caller must ensure r12 holds the entry point
* address (so that the function can quickly
* establish addressability).
*/
regs->gpr[12] = start;
/* Make sure that's restored on entry to userspace. */
set_thread_flag(TIF_RESTOREALL);
} else {
unsigned long 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->gpr[2] = toc;
}
regs_set_return_ip(regs, entry);
regs_set_return_msr(regs, MSR_USER64);
} else {
regs->gpr[2] = 0;
regs_set_return_ip(regs, start);
regs_set_return_msr(regs, MSR_USER32);
}
#endif
#ifdef CONFIG_VSX
current->thread.used_vsr = 0;
#endif
current->thread.load_slb = 0;
current->thread.load_fp = 0;
#ifdef CONFIG_PPC_FPU_REGS
memset(&current->thread.fp_state, 0, sizeof(current->thread.fp_state));
current->thread.fp_save_area = NULL;
#endif
#ifdef CONFIG_ALTIVEC
memset(&current->thread.vr_state, 0, sizeof(current->thread.vr_state));
current->thread.vr_state.vscr.u[3] = 0x00010000; /* Java mode disabled */
current->thread.vr_save_area = NULL;
current->thread.vrsave = 0;
current->thread.used_vr = 0;
current->thread.load_vec = 0;
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_SPE
memset(current->thread.evr, 0, sizeof(current->thread.evr));
current->thread.acc = 0;
current->thread.spefscr = 0;
current->thread.used_spe = 0;
#endif /* CONFIG_SPE */
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
current->thread.tm_tfhar = 0;
current->thread.tm_texasr = 0;
current->thread.tm_tfiar = 0;
current->thread.load_tm = 0;
#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
}
EXPORT_SYMBOL(start_thread);
#define PR_FP_ALL_EXCEPT (PR_FP_EXC_DIV | PR_FP_EXC_OVF | PR_FP_EXC_UND \
| PR_FP_EXC_RES | PR_FP_EXC_INV)
int set_fpexc_mode(struct task_struct *tsk, unsigned int val)
{
struct pt_regs *regs = tsk->thread.regs;
/* This is a bit hairy. If we are an SPE enabled processor
* (have embedded fp) we store the IEEE exception enable flags in
* fpexc_mode. fpexc_mode is also used for setting FP exception
* mode (asyn, precise, disabled) for 'Classic' FP. */
if (val & PR_FP_EXC_SW_ENABLE) {
if (cpu_has_feature(CPU_FTR_SPE)) {
/*
* When the sticky exception bits are set
* directly by userspace, it must call prctl
* with PR_GET_FPEXC (with PR_FP_EXC_SW_ENABLE
* in the existing prctl settings) or
* PR_SET_FPEXC (with PR_FP_EXC_SW_ENABLE in
* the bits being set). <fenv.h> functions
* saving and restoring the whole
* floating-point environment need to do so
* anyway to restore the prctl settings from
* the saved environment.
*/
#ifdef CONFIG_SPE
tsk->thread.spefscr_last = mfspr(SPRN_SPEFSCR);
tsk->thread.fpexc_mode = val &
(PR_FP_EXC_SW_ENABLE | PR_FP_ALL_EXCEPT);
#endif
return 0;
} else {
return -EINVAL;
}
}
/* 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_set_return_msr(regs, (regs->msr & ~(MSR_FE0|MSR_FE1))
| tsk->thread.fpexc_mode);
}
return 0;
}
int get_fpexc_mode(struct task_struct *tsk, unsigned long adr)
{
unsigned int val = 0;
if (tsk->thread.fpexc_mode & PR_FP_EXC_SW_ENABLE) {
if (cpu_has_feature(CPU_FTR_SPE)) {
/*
* When the sticky exception bits are set
* directly by userspace, it must call prctl
* with PR_GET_FPEXC (with PR_FP_EXC_SW_ENABLE
* in the existing prctl settings) or
* PR_SET_FPEXC (with PR_FP_EXC_SW_ENABLE in
* the bits being set). <fenv.h> functions
* saving and restoring the whole
* floating-point environment need to do so
* anyway to restore the prctl settings from
* the saved environment.
*/
#ifdef CONFIG_SPE
tsk->thread.spefscr_last = mfspr(SPRN_SPEFSCR);
val = tsk->thread.fpexc_mode;
#endif
} else
return -EINVAL;
} else {
val = __unpack_fe01(tsk->thread.fpexc_mode);
}
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_set_return_msr(regs, regs->msr & ~MSR_LE);
else if (val == PR_ENDIAN_LITTLE || val == PR_ENDIAN_PPC_LITTLE)
regs_set_return_msr(regs, 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);
}
static inline int valid_irq_stack(unsigned long sp, struct task_struct *p,
unsigned long nbytes)
{
unsigned long stack_page;
unsigned long cpu = task_cpu(p);
stack_page = (unsigned long)hardirq_ctx[cpu];
if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes)
return 1;
stack_page = (unsigned long)softirq_ctx[cpu];
if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes)
return 1;
return 0;
}
static inline int valid_emergency_stack(unsigned long sp, struct task_struct *p,
unsigned long nbytes)
{
#ifdef CONFIG_PPC64
unsigned long stack_page;
unsigned long cpu = task_cpu(p);
if (!paca_ptrs)
return 0;
stack_page = (unsigned long)paca_ptrs[cpu]->emergency_sp - THREAD_SIZE;
if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes)
return 1;
# ifdef CONFIG_PPC_BOOK3S_64
stack_page = (unsigned long)paca_ptrs[cpu]->nmi_emergency_sp - THREAD_SIZE;
if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes)
return 1;
stack_page = (unsigned long)paca_ptrs[cpu]->mc_emergency_sp - THREAD_SIZE;
if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes)
return 1;
# endif
#endif
return 0;
}
int validate_sp(unsigned long sp, struct task_struct *p,
unsigned long nbytes)
{
unsigned long stack_page = (unsigned long)task_stack_page(p);
if (sp < THREAD_SIZE)
return 0;
if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes)
return 1;
if (valid_irq_stack(sp, p, nbytes))
return 1;
return valid_emergency_stack(sp, p, nbytes);
}
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,
unsigned long *stack,
const char *loglvl)
{
unsigned long sp, ip, lr, newsp;
int count = 0;
int firstframe = 1;
unsigned long ret_addr;
int ftrace_idx = 0;
if (tsk == NULL)
tsk = current;
if (!try_get_task_stack(tsk))
return;
sp = (unsigned long) stack;
if (sp == 0) {
if (tsk == current)
sp = current_stack_frame();
else
sp = tsk->thread.ksp;
}
lr = 0;
printk("%sCall Trace:\n", loglvl);
do {
if (!validate_sp(sp, tsk, STACK_FRAME_OVERHEAD))
break;
stack = (unsigned long *) sp;
newsp = stack[0];
ip = stack[STACK_FRAME_LR_SAVE];
if (!firstframe || ip != lr) {
printk("%s["REG"] ["REG"] %pS",
loglvl, sp, ip, (void *)ip);
ret_addr = ftrace_graph_ret_addr(current,
&ftrace_idx, ip, stack);
if (ret_addr != ip)
pr_cont(" (%pS)", (void *)ret_addr);
if (firstframe)
pr_cont(" (unreliable)");
pr_cont("\n");
}
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_FRAME_WITH_PT_REGS)
&& stack[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
struct pt_regs *regs = (struct pt_regs *)
(sp + STACK_FRAME_OVERHEAD);
lr = regs->link;
printk("%s--- interrupt: %lx at %pS\n",
loglvl, regs->trap, (void *)regs->nip);
__show_regs(regs);
printk("%s--- interrupt: %lx\n",
loglvl, regs->trap);
firstframe = 1;
}
sp = newsp;
} while (count++ < kstack_depth_to_print);
put_task_stack(tsk);
}
#ifdef CONFIG_PPC64
/* Called with hard IRQs off */
void notrace __ppc64_runlatch_on(void)
{
struct thread_info *ti = current_thread_info();
if (cpu_has_feature(CPU_FTR_ARCH_206)) {
/*
* Least significant bit (RUN) is the only writable bit of
* the CTRL register, so we can avoid mfspr. 2.06 is not the
* earliest ISA where this is the case, but it's convenient.
*/
mtspr(SPRN_CTRLT, CTRL_RUNLATCH);
} else {
unsigned long ctrl;
/*
* Some architectures (e.g., Cell) have writable fields other
* than RUN, so do the read-modify-write.
*/
ctrl = mfspr(SPRN_CTRLF);
ctrl |= CTRL_RUNLATCH;
mtspr(SPRN_CTRLT, ctrl);
}
ti->local_flags |= _TLF_RUNLATCH;
}
/* Called with hard IRQs off */
void notrace __ppc64_runlatch_off(void)
{
struct thread_info *ti = current_thread_info();
ti->local_flags &= ~_TLF_RUNLATCH;
if (cpu_has_feature(CPU_FTR_ARCH_206)) {
mtspr(SPRN_CTRLT, 0);
} else {
unsigned long ctrl;
ctrl = mfspr(SPRN_CTRLF);
ctrl &= ~CTRL_RUNLATCH;
mtspr(SPRN_CTRLT, ctrl);
}
}
#endif /* CONFIG_PPC64 */
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 = (get_random_long() % (1UL<<(23-PAGE_SHIFT)));
else
rnd = (get_random_long() % (1UL<<(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_BOOK3S_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. We don't need to worry about radix. For
* radix, mmu_highuser_ssize remains unchanged from 256MB.
*/
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;
}
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