// SPDX-License-Identifier: GPL-2.0 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "process.h" /* * per-CPU TSS segments. Threads are completely 'soft' on Linux, * no more per-task TSS's. The TSS size is kept cacheline-aligned * so they are allowed to end up in the .data..cacheline_aligned * section. Since TSS's are completely CPU-local, we want them * on exact cacheline boundaries, to eliminate cacheline ping-pong. */ __visible DEFINE_PER_CPU_PAGE_ALIGNED(struct tss_struct, cpu_tss_rw) = { .x86_tss = { /* * .sp0 is only used when entering ring 0 from a lower * privilege level. Since the init task never runs anything * but ring 0 code, there is no need for a valid value here. * Poison it. */ .sp0 = (1UL << (BITS_PER_LONG-1)) + 1, /* * .sp1 is cpu_current_top_of_stack. The init task never * runs user code, but cpu_current_top_of_stack should still * be well defined before the first context switch. */ .sp1 = TOP_OF_INIT_STACK, #ifdef CONFIG_X86_32 .ss0 = __KERNEL_DS, .ss1 = __KERNEL_CS, #endif .io_bitmap_base = IO_BITMAP_OFFSET_INVALID, }, }; EXPORT_PER_CPU_SYMBOL(cpu_tss_rw); DEFINE_PER_CPU(bool, __tss_limit_invalid); EXPORT_PER_CPU_SYMBOL_GPL(__tss_limit_invalid); /* * this gets called so that we can store lazy 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) { memcpy(dst, src, arch_task_struct_size); #ifdef CONFIG_VM86 dst->thread.vm86 = NULL; #endif return fpu__copy(dst, src); } /* * Free current thread data structures etc.. */ void exit_thread(struct task_struct *tsk) { struct thread_struct *t = &tsk->thread; struct fpu *fpu = &t->fpu; if (test_thread_flag(TIF_IO_BITMAP)) io_bitmap_exit(); free_vm86(t); fpu__drop(fpu); } static int set_new_tls(struct task_struct *p, unsigned long tls) { struct user_desc __user *utls = (struct user_desc __user *)tls; if (in_ia32_syscall()) return do_set_thread_area(p, -1, utls, 0); else return do_set_thread_area_64(p, ARCH_SET_FS, tls); } int copy_thread_tls(unsigned long clone_flags, unsigned long sp, unsigned long arg, struct task_struct *p, unsigned long tls) { struct inactive_task_frame *frame; struct fork_frame *fork_frame; struct pt_regs *childregs; int ret = 0; childregs = task_pt_regs(p); fork_frame = container_of(childregs, struct fork_frame, regs); frame = &fork_frame->frame; frame->bp = 0; frame->ret_addr = (unsigned long) ret_from_fork; p->thread.sp = (unsigned long) fork_frame; p->thread.io_bitmap = NULL; memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps)); #ifdef CONFIG_X86_64 savesegment(gs, p->thread.gsindex); p->thread.gsbase = p->thread.gsindex ? 0 : current->thread.gsbase; savesegment(fs, p->thread.fsindex); p->thread.fsbase = p->thread.fsindex ? 0 : current->thread.fsbase; savesegment(es, p->thread.es); savesegment(ds, p->thread.ds); #else p->thread.sp0 = (unsigned long) (childregs + 1); /* * Clear all status flags including IF and set fixed bit. 64bit * does not have this initialization as the frame does not contain * flags. The flags consistency (especially vs. AC) is there * ensured via objtool, which lacks 32bit support. */ frame->flags = X86_EFLAGS_FIXED; #endif /* Kernel thread ? */ if (unlikely(p->flags & PF_KTHREAD)) { memset(childregs, 0, sizeof(struct pt_regs)); kthread_frame_init(frame, sp, arg); return 0; } frame->bx = 0; *childregs = *current_pt_regs(); childregs->ax = 0; if (sp) childregs->sp = sp; #ifdef CONFIG_X86_32 task_user_gs(p) = get_user_gs(current_pt_regs()); #endif /* Set a new TLS for the child thread? */ if (clone_flags & CLONE_SETTLS) ret = set_new_tls(p, tls); if (!ret && unlikely(test_tsk_thread_flag(current, TIF_IO_BITMAP))) io_bitmap_share(p); return ret; } void flush_thread(void) { struct task_struct *tsk = current; flush_ptrace_hw_breakpoint(tsk); memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array)); fpu__clear(&tsk->thread.fpu); } void disable_TSC(void) { preempt_disable(); if (!test_and_set_thread_flag(TIF_NOTSC)) /* * Must flip the CPU state synchronously with * TIF_NOTSC in the current running context. */ cr4_set_bits(X86_CR4_TSD); preempt_enable(); } static void enable_TSC(void) { preempt_disable(); if (test_and_clear_thread_flag(TIF_NOTSC)) /* * Must flip the CPU state synchronously with * TIF_NOTSC in the current running context. */ cr4_clear_bits(X86_CR4_TSD); preempt_enable(); } int get_tsc_mode(unsigned long adr) { unsigned int val; if (test_thread_flag(TIF_NOTSC)) val = PR_TSC_SIGSEGV; else val = PR_TSC_ENABLE; return put_user(val, (unsigned int __user *)adr); } int set_tsc_mode(unsigned int val) { if (val == PR_TSC_SIGSEGV) disable_TSC(); else if (val == PR_TSC_ENABLE) enable_TSC(); else return -EINVAL; return 0; } DEFINE_PER_CPU(u64, msr_misc_features_shadow); static void set_cpuid_faulting(bool on) { u64 msrval; msrval = this_cpu_read(msr_misc_features_shadow); msrval &= ~MSR_MISC_FEATURES_ENABLES_CPUID_FAULT; msrval |= (on << MSR_MISC_FEATURES_ENABLES_CPUID_FAULT_BIT); this_cpu_write(msr_misc_features_shadow, msrval); wrmsrl(MSR_MISC_FEATURES_ENABLES, msrval); } static void disable_cpuid(void) { preempt_disable(); if (!test_and_set_thread_flag(TIF_NOCPUID)) { /* * Must flip the CPU state synchronously with * TIF_NOCPUID in the current running context. */ set_cpuid_faulting(true); } preempt_enable(); } static void enable_cpuid(void) { preempt_disable(); if (test_and_clear_thread_flag(TIF_NOCPUID)) { /* * Must flip the CPU state synchronously with * TIF_NOCPUID in the current running context. */ set_cpuid_faulting(false); } preempt_enable(); } static int get_cpuid_mode(void) { return !test_thread_flag(TIF_NOCPUID); } static int set_cpuid_mode(struct task_struct *task, unsigned long cpuid_enabled) { if (!boot_cpu_has(X86_FEATURE_CPUID_FAULT)) return -ENODEV; if (cpuid_enabled) enable_cpuid(); else disable_cpuid(); return 0; } /* * Called immediately after a successful exec. */ void arch_setup_new_exec(void) { /* If cpuid was previously disabled for this task, re-enable it. */ if (test_thread_flag(TIF_NOCPUID)) enable_cpuid(); /* * Don't inherit TIF_SSBD across exec boundary when * PR_SPEC_DISABLE_NOEXEC is used. */ if (test_thread_flag(TIF_SSBD) && task_spec_ssb_noexec(current)) { clear_thread_flag(TIF_SSBD); task_clear_spec_ssb_disable(current); task_clear_spec_ssb_noexec(current); speculation_ctrl_update(task_thread_info(current)->flags); } } #ifdef CONFIG_X86_IOPL_IOPERM static inline void tss_invalidate_io_bitmap(struct tss_struct *tss) { /* * Invalidate the I/O bitmap by moving io_bitmap_base outside the * TSS limit so any subsequent I/O access from user space will * trigger a #GP. * * This is correct even when VMEXIT rewrites the TSS limit * to 0x67 as the only requirement is that the base points * outside the limit. */ tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET_INVALID; } static inline void switch_to_bitmap(unsigned long tifp) { /* * Invalidate I/O bitmap if the previous task used it. This prevents * any possible leakage of an active I/O bitmap. * * If the next task has an I/O bitmap it will handle it on exit to * user mode. */ if (tifp & _TIF_IO_BITMAP) tss_invalidate_io_bitmap(this_cpu_ptr(&cpu_tss_rw)); } static void tss_copy_io_bitmap(struct tss_struct *tss, struct io_bitmap *iobm) { /* * Copy at least the byte range of the incoming tasks bitmap which * covers the permitted I/O ports. * * If the previous task which used an I/O bitmap had more bits * permitted, then the copy needs to cover those as well so they * get turned off. */ memcpy(tss->io_bitmap.bitmap, iobm->bitmap, max(tss->io_bitmap.prev_max, iobm->max)); /* * Store the new max and the sequence number of this bitmap * and a pointer to the bitmap itself. */ tss->io_bitmap.prev_max = iobm->max; tss->io_bitmap.prev_sequence = iobm->sequence; } /** * tss_update_io_bitmap - Update I/O bitmap before exiting to usermode */ void tss_update_io_bitmap(void) { struct tss_struct *tss = this_cpu_ptr(&cpu_tss_rw); struct thread_struct *t = ¤t->thread; u16 *base = &tss->x86_tss.io_bitmap_base; if (!test_thread_flag(TIF_IO_BITMAP)) { tss_invalidate_io_bitmap(tss); return; } if (IS_ENABLED(CONFIG_X86_IOPL_IOPERM) && t->iopl_emul == 3) { *base = IO_BITMAP_OFFSET_VALID_ALL; } else { struct io_bitmap *iobm = t->io_bitmap; /* * Only copy bitmap data when the sequence number differs. The * update time is accounted to the incoming task. */ if (tss->io_bitmap.prev_sequence != iobm->sequence) tss_copy_io_bitmap(tss, iobm); /* Enable the bitmap */ *base = IO_BITMAP_OFFSET_VALID_MAP; } /* * Make sure that the TSS limit is covering the IO bitmap. It might have * been cut down by a VMEXIT to 0x67 which would cause a subsequent I/O * access from user space to trigger a #GP because tbe bitmap is outside * the TSS limit. */ refresh_tss_limit(); } #else /* CONFIG_X86_IOPL_IOPERM */ static inline void switch_to_bitmap(unsigned long tifp) { } #endif #ifdef CONFIG_SMP struct ssb_state { struct ssb_state *shared_state; raw_spinlock_t lock; unsigned int disable_state; unsigned long local_state; }; #define LSTATE_SSB 0 static DEFINE_PER_CPU(struct ssb_state, ssb_state); void speculative_store_bypass_ht_init(void) { struct ssb_state *st = this_cpu_ptr(&ssb_state); unsigned int this_cpu = smp_processor_id(); unsigned int cpu; st->local_state = 0; /* * Shared state setup happens once on the first bringup * of the CPU. It's not destroyed on CPU hotunplug. */ if (st->shared_state) return; raw_spin_lock_init(&st->lock); /* * Go over HT siblings and check whether one of them has set up the * shared state pointer already. */ for_each_cpu(cpu, topology_sibling_cpumask(this_cpu)) { if (cpu == this_cpu) continue; if (!per_cpu(ssb_state, cpu).shared_state) continue; /* Link it to the state of the sibling: */ st->shared_state = per_cpu(ssb_state, cpu).shared_state; return; } /* * First HT sibling to come up on the core. Link shared state of * the first HT sibling to itself. The siblings on the same core * which come up later will see the shared state pointer and link * themself to the state of this CPU. */ st->shared_state = st; } /* * Logic is: First HT sibling enables SSBD for both siblings in the core * and last sibling to disable it, disables it for the whole core. This how * MSR_SPEC_CTRL works in "hardware": * * CORE_SPEC_CTRL = THREAD0_SPEC_CTRL | THREAD1_SPEC_CTRL */ static __always_inline void amd_set_core_ssb_state(unsigned long tifn) { struct ssb_state *st = this_cpu_ptr(&ssb_state); u64 msr = x86_amd_ls_cfg_base; if (!static_cpu_has(X86_FEATURE_ZEN)) { msr |= ssbd_tif_to_amd_ls_cfg(tifn); wrmsrl(MSR_AMD64_LS_CFG, msr); return; } if (tifn & _TIF_SSBD) { /* * Since this can race with prctl(), block reentry on the * same CPU. */ if (__test_and_set_bit(LSTATE_SSB, &st->local_state)) return; msr |= x86_amd_ls_cfg_ssbd_mask; raw_spin_lock(&st->shared_state->lock); /* First sibling enables SSBD: */ if (!st->shared_state->disable_state) wrmsrl(MSR_AMD64_LS_CFG, msr); st->shared_state->disable_state++; raw_spin_unlock(&st->shared_state->lock); } else { if (!__test_and_clear_bit(LSTATE_SSB, &st->local_state)) return; raw_spin_lock(&st->shared_state->lock); st->shared_state->disable_state--; if (!st->shared_state->disable_state) wrmsrl(MSR_AMD64_LS_CFG, msr); raw_spin_unlock(&st->shared_state->lock); } } #else static __always_inline void amd_set_core_ssb_state(unsigned long tifn) { u64 msr = x86_amd_ls_cfg_base | ssbd_tif_to_amd_ls_cfg(tifn); wrmsrl(MSR_AMD64_LS_CFG, msr); } #endif static __always_inline void amd_set_ssb_virt_state(unsigned long tifn) { /* * SSBD has the same definition in SPEC_CTRL and VIRT_SPEC_CTRL, * so ssbd_tif_to_spec_ctrl() just works. */ wrmsrl(MSR_AMD64_VIRT_SPEC_CTRL, ssbd_tif_to_spec_ctrl(tifn)); } /* * Update the MSRs managing speculation control, during context switch. * * tifp: Previous task's thread flags * tifn: Next task's thread flags */ static __always_inline void __speculation_ctrl_update(unsigned long tifp, unsigned long tifn) { unsigned long tif_diff = tifp ^ tifn; u64 msr = x86_spec_ctrl_base; bool updmsr = false; lockdep_assert_irqs_disabled(); /* * If TIF_SSBD is different, select the proper mitigation * method. Note that if SSBD mitigation is disabled or permanentely * enabled this branch can't be taken because nothing can set * TIF_SSBD. */ if (tif_diff & _TIF_SSBD) { if (static_cpu_has(X86_FEATURE_VIRT_SSBD)) { amd_set_ssb_virt_state(tifn); } else if (static_cpu_has(X86_FEATURE_LS_CFG_SSBD)) { amd_set_core_ssb_state(tifn); } else if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) || static_cpu_has(X86_FEATURE_AMD_SSBD)) { msr |= ssbd_tif_to_spec_ctrl(tifn); updmsr = true; } } /* * Only evaluate TIF_SPEC_IB if conditional STIBP is enabled, * otherwise avoid the MSR write. */ if (IS_ENABLED(CONFIG_SMP) && static_branch_unlikely(&switch_to_cond_stibp)) { updmsr |= !!(tif_diff & _TIF_SPEC_IB); msr |= stibp_tif_to_spec_ctrl(tifn); } if (updmsr) wrmsrl(MSR_IA32_SPEC_CTRL, msr); } static unsigned long speculation_ctrl_update_tif(struct task_struct *tsk) { if (test_and_clear_tsk_thread_flag(tsk, TIF_SPEC_FORCE_UPDATE)) { if (task_spec_ssb_disable(tsk)) set_tsk_thread_flag(tsk, TIF_SSBD); else clear_tsk_thread_flag(tsk, TIF_SSBD); if (task_spec_ib_disable(tsk)) set_tsk_thread_flag(tsk, TIF_SPEC_IB); else clear_tsk_thread_flag(tsk, TIF_SPEC_IB); } /* Return the updated threadinfo flags*/ return task_thread_info(tsk)->flags; } void speculation_ctrl_update(unsigned long tif) { unsigned long flags; /* Forced update. Make sure all relevant TIF flags are different */ local_irq_save(flags); __speculation_ctrl_update(~tif, tif); local_irq_restore(flags); } /* Called from seccomp/prctl update */ void speculation_ctrl_update_current(void) { preempt_disable(); speculation_ctrl_update(speculation_ctrl_update_tif(current)); preempt_enable(); } void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p) { unsigned long tifp, tifn; tifn = READ_ONCE(task_thread_info(next_p)->flags); tifp = READ_ONCE(task_thread_info(prev_p)->flags); switch_to_bitmap(tifp); propagate_user_return_notify(prev_p, next_p); if ((tifp & _TIF_BLOCKSTEP || tifn & _TIF_BLOCKSTEP) && arch_has_block_step()) { unsigned long debugctl, msk; rdmsrl(MSR_IA32_DEBUGCTLMSR, debugctl); debugctl &= ~DEBUGCTLMSR_BTF; msk = tifn & _TIF_BLOCKSTEP; debugctl |= (msk >> TIF_BLOCKSTEP) << DEBUGCTLMSR_BTF_SHIFT; wrmsrl(MSR_IA32_DEBUGCTLMSR, debugctl); } if ((tifp ^ tifn) & _TIF_NOTSC) cr4_toggle_bits_irqsoff(X86_CR4_TSD); if ((tifp ^ tifn) & _TIF_NOCPUID) set_cpuid_faulting(!!(tifn & _TIF_NOCPUID)); if (likely(!((tifp | tifn) & _TIF_SPEC_FORCE_UPDATE))) { __speculation_ctrl_update(tifp, tifn); } else { speculation_ctrl_update_tif(prev_p); tifn = speculation_ctrl_update_tif(next_p); /* Enforce MSR update to ensure consistent state */ __speculation_ctrl_update(~tifn, tifn); } } /* * Idle related variables and functions */ unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE; EXPORT_SYMBOL(boot_option_idle_override); static void (*x86_idle)(void); #ifndef CONFIG_SMP static inline void play_dead(void) { BUG(); } #endif void arch_cpu_idle_enter(void) { tsc_verify_tsc_adjust(false); local_touch_nmi(); } void arch_cpu_idle_dead(void) { play_dead(); } /* * Called from the generic idle code. */ void arch_cpu_idle(void) { x86_idle(); } /* * We use this if we don't have any better idle routine.. */ void __cpuidle default_idle(void) { trace_cpu_idle_rcuidle(1, smp_processor_id()); safe_halt(); trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id()); } #if defined(CONFIG_APM_MODULE) || defined(CONFIG_HALTPOLL_CPUIDLE_MODULE) EXPORT_SYMBOL(default_idle); #endif #ifdef CONFIG_XEN bool xen_set_default_idle(void) { bool ret = !!x86_idle; x86_idle = default_idle; return ret; } #endif void stop_this_cpu(void *dummy) { local_irq_disable(); /* * Remove this CPU: */ set_cpu_online(smp_processor_id(), false); disable_local_APIC(); mcheck_cpu_clear(this_cpu_ptr(&cpu_info)); /* * Use wbinvd on processors that support SME. This provides support * for performing a successful kexec when going from SME inactive * to SME active (or vice-versa). The cache must be cleared so that * if there are entries with the same physical address, both with and * without the encryption bit, they don't race each other when flushed * and potentially end up with the wrong entry being committed to * memory. */ if (boot_cpu_has(X86_FEATURE_SME)) native_wbinvd(); for (;;) { /* * Use native_halt() so that memory contents don't change * (stack usage and variables) after possibly issuing the * native_wbinvd() above. */ native_halt(); } } /* * AMD Erratum 400 aware idle routine. We handle it the same way as C3 power * states (local apic timer and TSC stop). */ static void amd_e400_idle(void) { /* * We cannot use static_cpu_has_bug() here because X86_BUG_AMD_APIC_C1E * gets set after static_cpu_has() places have been converted via * alternatives. */ if (!boot_cpu_has_bug(X86_BUG_AMD_APIC_C1E)) { default_idle(); return; } tick_broadcast_enter(); default_idle(); /* * The switch back from broadcast mode needs to be called with * interrupts disabled. */ local_irq_disable(); tick_broadcast_exit(); local_irq_enable(); } /* * Intel Core2 and older machines prefer MWAIT over HALT for C1. * We can't rely on cpuidle installing MWAIT, because it will not load * on systems that support only C1 -- so the boot default must be MWAIT. * * Some AMD machines are the opposite, they depend on using HALT. * * So for default C1, which is used during boot until cpuidle loads, * use MWAIT-C1 on Intel HW that has it, else use HALT. */ static int prefer_mwait_c1_over_halt(const struct cpuinfo_x86 *c) { if (c->x86_vendor != X86_VENDOR_INTEL) return 0; if (!cpu_has(c, X86_FEATURE_MWAIT) || boot_cpu_has_bug(X86_BUG_MONITOR)) return 0; return 1; } /* * MONITOR/MWAIT with no hints, used for default C1 state. This invokes MWAIT * with interrupts enabled and no flags, which is backwards compatible with the * original MWAIT implementation. */ static __cpuidle void mwait_idle(void) { if (!current_set_polling_and_test()) { trace_cpu_idle_rcuidle(1, smp_processor_id()); if (this_cpu_has(X86_BUG_CLFLUSH_MONITOR)) { mb(); /* quirk */ clflush((void *)¤t_thread_info()->flags); mb(); /* quirk */ } __monitor((void *)¤t_thread_info()->flags, 0, 0); if (!need_resched()) __sti_mwait(0, 0); else local_irq_enable(); trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id()); } else { local_irq_enable(); } __current_clr_polling(); } void select_idle_routine(const struct cpuinfo_x86 *c) { #ifdef CONFIG_SMP if (boot_option_idle_override == IDLE_POLL && smp_num_siblings > 1) pr_warn_once("WARNING: polling idle and HT enabled, performance may degrade\n"); #endif if (x86_idle || boot_option_idle_override == IDLE_POLL) return; if (boot_cpu_has_bug(X86_BUG_AMD_E400)) { pr_info("using AMD E400 aware idle routine\n"); x86_idle = amd_e400_idle; } else if (prefer_mwait_c1_over_halt(c)) { pr_info("using mwait in idle threads\n"); x86_idle = mwait_idle; } else x86_idle = default_idle; } void amd_e400_c1e_apic_setup(void) { if (boot_cpu_has_bug(X86_BUG_AMD_APIC_C1E)) { pr_info("Switch to broadcast mode on CPU%d\n", smp_processor_id()); local_irq_disable(); tick_broadcast_force(); local_irq_enable(); } } void __init arch_post_acpi_subsys_init(void) { u32 lo, hi; if (!boot_cpu_has_bug(X86_BUG_AMD_E400)) return; /* * AMD E400 detection needs to happen after ACPI has been enabled. If * the machine is affected K8_INTP_C1E_ACTIVE_MASK bits are set in * MSR_K8_INT_PENDING_MSG. */ rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi); if (!(lo & K8_INTP_C1E_ACTIVE_MASK)) return; boot_cpu_set_bug(X86_BUG_AMD_APIC_C1E); if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC)) mark_tsc_unstable("TSC halt in AMD C1E"); pr_info("System has AMD C1E enabled\n"); } static int __init idle_setup(char *str) { if (!str) return -EINVAL; if (!strcmp(str, "poll")) { pr_info("using polling idle threads\n"); boot_option_idle_override = IDLE_POLL; cpu_idle_poll_ctrl(true); } else if (!strcmp(str, "halt")) { /* * When the boot option of idle=halt is added, halt is * forced to be used for CPU idle. In such case CPU C2/C3 * won't be used again. * To continue to load the CPU idle driver, don't touch * the boot_option_idle_override. */ x86_idle = default_idle; boot_option_idle_override = IDLE_HALT; } else if (!strcmp(str, "nomwait")) { /* * If the boot option of "idle=nomwait" is added, * it means that mwait will be disabled for CPU C2/C3 * states. In such case it won't touch the variable * of boot_option_idle_override. */ boot_option_idle_override = IDLE_NOMWAIT; } else return -1; return 0; } early_param("idle", idle_setup); unsigned long arch_align_stack(unsigned long sp) { if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) sp -= get_random_int() % 8192; return sp & ~0xf; } unsigned long arch_randomize_brk(struct mm_struct *mm) { return randomize_page(mm->brk, 0x02000000); } /* * Called from fs/proc with a reference on @p to find the function * which called into schedule(). This needs to be done carefully * because the task might wake up and we might look at a stack * changing under us. */ unsigned long get_wchan(struct task_struct *p) { unsigned long start, bottom, top, sp, fp, ip, ret = 0; int count = 0; if (p == current || p->state == TASK_RUNNING) return 0; if (!try_get_task_stack(p)) return 0; start = (unsigned long)task_stack_page(p); if (!start) goto out; /* * Layout of the stack page: * * ----------- topmax = start + THREAD_SIZE - sizeof(unsigned long) * PADDING * ----------- top = topmax - TOP_OF_KERNEL_STACK_PADDING * stack * ----------- bottom = start * * The tasks stack pointer points at the location where the * framepointer is stored. The data on the stack is: * ... IP FP ... IP FP * * We need to read FP and IP, so we need to adjust the upper * bound by another unsigned long. */ top = start + THREAD_SIZE - TOP_OF_KERNEL_STACK_PADDING; top -= 2 * sizeof(unsigned long); bottom = start; sp = READ_ONCE(p->thread.sp); if (sp < bottom || sp > top) goto out; fp = READ_ONCE_NOCHECK(((struct inactive_task_frame *)sp)->bp); do { if (fp < bottom || fp > top) goto out; ip = READ_ONCE_NOCHECK(*(unsigned long *)(fp + sizeof(unsigned long))); if (!in_sched_functions(ip)) { ret = ip; goto out; } fp = READ_ONCE_NOCHECK(*(unsigned long *)fp); } while (count++ < 16 && p->state != TASK_RUNNING); out: put_task_stack(p); return ret; } long do_arch_prctl_common(struct task_struct *task, int option, unsigned long cpuid_enabled) { switch (option) { case ARCH_GET_CPUID: return get_cpuid_mode(); case ARCH_SET_CPUID: return set_cpuid_mode(task, cpuid_enabled); } return -EINVAL; }