diff options
Diffstat (limited to 'ANDROID_3.4.5/arch/x86/mm/kmmio.c')
| -rw-r--r-- | ANDROID_3.4.5/arch/x86/mm/kmmio.c | 590 |
1 files changed, 0 insertions, 590 deletions
diff --git a/ANDROID_3.4.5/arch/x86/mm/kmmio.c b/ANDROID_3.4.5/arch/x86/mm/kmmio.c deleted file mode 100644 index e5d5e2ce..00000000 --- a/ANDROID_3.4.5/arch/x86/mm/kmmio.c +++ /dev/null @@ -1,590 +0,0 @@ -/* Support for MMIO probes. - * Benfit many code from kprobes - * (C) 2002 Louis Zhuang <louis.zhuang@intel.com>. - * 2007 Alexander Eichner - * 2008 Pekka Paalanen <pq@iki.fi> - */ - -#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt - -#include <linux/list.h> -#include <linux/rculist.h> -#include <linux/spinlock.h> -#include <linux/hash.h> -#include <linux/init.h> -#include <linux/module.h> -#include <linux/kernel.h> -#include <linux/uaccess.h> -#include <linux/ptrace.h> -#include <linux/preempt.h> -#include <linux/percpu.h> -#include <linux/kdebug.h> -#include <linux/mutex.h> -#include <linux/io.h> -#include <linux/slab.h> -#include <asm/cacheflush.h> -#include <asm/tlbflush.h> -#include <linux/errno.h> -#include <asm/debugreg.h> -#include <linux/mmiotrace.h> - -#define KMMIO_PAGE_HASH_BITS 4 -#define KMMIO_PAGE_TABLE_SIZE (1 << KMMIO_PAGE_HASH_BITS) - -struct kmmio_fault_page { - struct list_head list; - struct kmmio_fault_page *release_next; - unsigned long page; /* location of the fault page */ - pteval_t old_presence; /* page presence prior to arming */ - bool armed; - - /* - * Number of times this page has been registered as a part - * of a probe. If zero, page is disarmed and this may be freed. - * Used only by writers (RCU) and post_kmmio_handler(). - * Protected by kmmio_lock, when linked into kmmio_page_table. - */ - int count; - - bool scheduled_for_release; -}; - -struct kmmio_delayed_release { - struct rcu_head rcu; - struct kmmio_fault_page *release_list; -}; - -struct kmmio_context { - struct kmmio_fault_page *fpage; - struct kmmio_probe *probe; - unsigned long saved_flags; - unsigned long addr; - int active; -}; - -static DEFINE_SPINLOCK(kmmio_lock); - -/* Protected by kmmio_lock */ -unsigned int kmmio_count; - -/* Read-protected by RCU, write-protected by kmmio_lock. */ -static struct list_head kmmio_page_table[KMMIO_PAGE_TABLE_SIZE]; -static LIST_HEAD(kmmio_probes); - -static struct list_head *kmmio_page_list(unsigned long page) -{ - return &kmmio_page_table[hash_long(page, KMMIO_PAGE_HASH_BITS)]; -} - -/* Accessed per-cpu */ -static DEFINE_PER_CPU(struct kmmio_context, kmmio_ctx); - -/* - * this is basically a dynamic stabbing problem: - * Could use the existing prio tree code or - * Possible better implementations: - * The Interval Skip List: A Data Structure for Finding All Intervals That - * Overlap a Point (might be simple) - * Space Efficient Dynamic Stabbing with Fast Queries - Mikkel Thorup - */ -/* Get the kmmio at this addr (if any). You must be holding RCU read lock. */ -static struct kmmio_probe *get_kmmio_probe(unsigned long addr) -{ - struct kmmio_probe *p; - list_for_each_entry_rcu(p, &kmmio_probes, list) { - if (addr >= p->addr && addr < (p->addr + p->len)) - return p; - } - return NULL; -} - -/* You must be holding RCU read lock. */ -static struct kmmio_fault_page *get_kmmio_fault_page(unsigned long page) -{ - struct list_head *head; - struct kmmio_fault_page *f; - - page &= PAGE_MASK; - head = kmmio_page_list(page); - list_for_each_entry_rcu(f, head, list) { - if (f->page == page) - return f; - } - return NULL; -} - -static void clear_pmd_presence(pmd_t *pmd, bool clear, pmdval_t *old) -{ - pmdval_t v = pmd_val(*pmd); - if (clear) { - *old = v & _PAGE_PRESENT; - v &= ~_PAGE_PRESENT; - } else /* presume this has been called with clear==true previously */ - v |= *old; - set_pmd(pmd, __pmd(v)); -} - -static void clear_pte_presence(pte_t *pte, bool clear, pteval_t *old) -{ - pteval_t v = pte_val(*pte); - if (clear) { - *old = v & _PAGE_PRESENT; - v &= ~_PAGE_PRESENT; - } else /* presume this has been called with clear==true previously */ - v |= *old; - set_pte_atomic(pte, __pte(v)); -} - -static int clear_page_presence(struct kmmio_fault_page *f, bool clear) -{ - unsigned int level; - pte_t *pte = lookup_address(f->page, &level); - - if (!pte) { - pr_err("no pte for page 0x%08lx\n", f->page); - return -1; - } - - switch (level) { - case PG_LEVEL_2M: - clear_pmd_presence((pmd_t *)pte, clear, &f->old_presence); - break; - case PG_LEVEL_4K: - clear_pte_presence(pte, clear, &f->old_presence); - break; - default: - pr_err("unexpected page level 0x%x.\n", level); - return -1; - } - - __flush_tlb_one(f->page); - return 0; -} - -/* - * Mark the given page as not present. Access to it will trigger a fault. - * - * Struct kmmio_fault_page is protected by RCU and kmmio_lock, but the - * protection is ignored here. RCU read lock is assumed held, so the struct - * will not disappear unexpectedly. Furthermore, the caller must guarantee, - * that double arming the same virtual address (page) cannot occur. - * - * Double disarming on the other hand is allowed, and may occur when a fault - * and mmiotrace shutdown happen simultaneously. - */ -static int arm_kmmio_fault_page(struct kmmio_fault_page *f) -{ - int ret; - WARN_ONCE(f->armed, KERN_ERR pr_fmt("kmmio page already armed.\n")); - if (f->armed) { - pr_warning("double-arm: page 0x%08lx, ref %d, old %d\n", - f->page, f->count, !!f->old_presence); - } - ret = clear_page_presence(f, true); - WARN_ONCE(ret < 0, KERN_ERR pr_fmt("arming 0x%08lx failed.\n"), - f->page); - f->armed = true; - return ret; -} - -/** Restore the given page to saved presence state. */ -static void disarm_kmmio_fault_page(struct kmmio_fault_page *f) -{ - int ret = clear_page_presence(f, false); - WARN_ONCE(ret < 0, - KERN_ERR "kmmio disarming 0x%08lx failed.\n", f->page); - f->armed = false; -} - -/* - * This is being called from do_page_fault(). - * - * We may be in an interrupt or a critical section. Also prefecthing may - * trigger a page fault. We may be in the middle of process switch. - * We cannot take any locks, because we could be executing especially - * within a kmmio critical section. - * - * Local interrupts are disabled, so preemption cannot happen. - * Do not enable interrupts, do not sleep, and watch out for other CPUs. - */ -/* - * Interrupts are disabled on entry as trap3 is an interrupt gate - * and they remain disabled throughout this function. - */ -int kmmio_handler(struct pt_regs *regs, unsigned long addr) -{ - struct kmmio_context *ctx; - struct kmmio_fault_page *faultpage; - int ret = 0; /* default to fault not handled */ - - /* - * Preemption is now disabled to prevent process switch during - * single stepping. We can only handle one active kmmio trace - * per cpu, so ensure that we finish it before something else - * gets to run. We also hold the RCU read lock over single - * stepping to avoid looking up the probe and kmmio_fault_page - * again. - */ - preempt_disable(); - rcu_read_lock(); - - faultpage = get_kmmio_fault_page(addr); - if (!faultpage) { - /* - * Either this page fault is not caused by kmmio, or - * another CPU just pulled the kmmio probe from under - * our feet. The latter case should not be possible. - */ - goto no_kmmio; - } - - ctx = &get_cpu_var(kmmio_ctx); - if (ctx->active) { - if (addr == ctx->addr) { - /* - * A second fault on the same page means some other - * condition needs handling by do_page_fault(), the - * page really not being present is the most common. - */ - pr_debug("secondary hit for 0x%08lx CPU %d.\n", - addr, smp_processor_id()); - - if (!faultpage->old_presence) - pr_info("unexpected secondary hit for address 0x%08lx on CPU %d.\n", - addr, smp_processor_id()); - } else { - /* - * Prevent overwriting already in-flight context. - * This should not happen, let's hope disarming at - * least prevents a panic. - */ - pr_emerg("recursive probe hit on CPU %d, for address 0x%08lx. Ignoring.\n", - smp_processor_id(), addr); - pr_emerg("previous hit was at 0x%08lx.\n", ctx->addr); - disarm_kmmio_fault_page(faultpage); - } - goto no_kmmio_ctx; - } - ctx->active++; - - ctx->fpage = faultpage; - ctx->probe = get_kmmio_probe(addr); - ctx->saved_flags = (regs->flags & (X86_EFLAGS_TF | X86_EFLAGS_IF)); - ctx->addr = addr; - - if (ctx->probe && ctx->probe->pre_handler) - ctx->probe->pre_handler(ctx->probe, regs, addr); - - /* - * Enable single-stepping and disable interrupts for the faulting - * context. Local interrupts must not get enabled during stepping. - */ - regs->flags |= X86_EFLAGS_TF; - regs->flags &= ~X86_EFLAGS_IF; - - /* Now we set present bit in PTE and single step. */ - disarm_kmmio_fault_page(ctx->fpage); - - /* - * If another cpu accesses the same page while we are stepping, - * the access will not be caught. It will simply succeed and the - * only downside is we lose the event. If this becomes a problem, - * the user should drop to single cpu before tracing. - */ - - put_cpu_var(kmmio_ctx); - return 1; /* fault handled */ - -no_kmmio_ctx: - put_cpu_var(kmmio_ctx); -no_kmmio: - rcu_read_unlock(); - preempt_enable_no_resched(); - return ret; -} - -/* - * Interrupts are disabled on entry as trap1 is an interrupt gate - * and they remain disabled throughout this function. - * This must always get called as the pair to kmmio_handler(). - */ -static int post_kmmio_handler(unsigned long condition, struct pt_regs *regs) -{ - int ret = 0; - struct kmmio_context *ctx = &get_cpu_var(kmmio_ctx); - - if (!ctx->active) { - /* - * debug traps without an active context are due to either - * something external causing them (f.e. using a debugger while - * mmio tracing enabled), or erroneous behaviour - */ - pr_warning("unexpected debug trap on CPU %d.\n", - smp_processor_id()); - goto out; - } - - if (ctx->probe && ctx->probe->post_handler) - ctx->probe->post_handler(ctx->probe, condition, regs); - - /* Prevent racing against release_kmmio_fault_page(). */ - spin_lock(&kmmio_lock); - if (ctx->fpage->count) - arm_kmmio_fault_page(ctx->fpage); - spin_unlock(&kmmio_lock); - - regs->flags &= ~X86_EFLAGS_TF; - regs->flags |= ctx->saved_flags; - - /* These were acquired in kmmio_handler(). */ - ctx->active--; - BUG_ON(ctx->active); - rcu_read_unlock(); - preempt_enable_no_resched(); - - /* - * if somebody else is singlestepping across a probe point, flags - * will have TF set, in which case, continue the remaining processing - * of do_debug, as if this is not a probe hit. - */ - if (!(regs->flags & X86_EFLAGS_TF)) - ret = 1; -out: - put_cpu_var(kmmio_ctx); - return ret; -} - -/* You must be holding kmmio_lock. */ -static int add_kmmio_fault_page(unsigned long page) -{ - struct kmmio_fault_page *f; - - page &= PAGE_MASK; - f = get_kmmio_fault_page(page); - if (f) { - if (!f->count) - arm_kmmio_fault_page(f); - f->count++; - return 0; - } - - f = kzalloc(sizeof(*f), GFP_ATOMIC); - if (!f) - return -1; - - f->count = 1; - f->page = page; - - if (arm_kmmio_fault_page(f)) { - kfree(f); - return -1; - } - - list_add_rcu(&f->list, kmmio_page_list(f->page)); - - return 0; -} - -/* You must be holding kmmio_lock. */ -static void release_kmmio_fault_page(unsigned long page, - struct kmmio_fault_page **release_list) -{ - struct kmmio_fault_page *f; - - page &= PAGE_MASK; - f = get_kmmio_fault_page(page); - if (!f) - return; - - f->count--; - BUG_ON(f->count < 0); - if (!f->count) { - disarm_kmmio_fault_page(f); - if (!f->scheduled_for_release) { - f->release_next = *release_list; - *release_list = f; - f->scheduled_for_release = true; - } - } -} - -/* - * With page-unaligned ioremaps, one or two armed pages may contain - * addresses from outside the intended mapping. Events for these addresses - * are currently silently dropped. The events may result only from programming - * mistakes by accessing addresses before the beginning or past the end of a - * mapping. - */ -int register_kmmio_probe(struct kmmio_probe *p) -{ - unsigned long flags; - int ret = 0; - unsigned long size = 0; - const unsigned long size_lim = p->len + (p->addr & ~PAGE_MASK); - - spin_lock_irqsave(&kmmio_lock, flags); - if (get_kmmio_probe(p->addr)) { - ret = -EEXIST; - goto out; - } - kmmio_count++; - list_add_rcu(&p->list, &kmmio_probes); - while (size < size_lim) { - if (add_kmmio_fault_page(p->addr + size)) - pr_err("Unable to set page fault.\n"); - size += PAGE_SIZE; - } -out: - spin_unlock_irqrestore(&kmmio_lock, flags); - /* - * XXX: What should I do here? - * Here was a call to global_flush_tlb(), but it does not exist - * anymore. It seems it's not needed after all. - */ - return ret; -} -EXPORT_SYMBOL(register_kmmio_probe); - -static void rcu_free_kmmio_fault_pages(struct rcu_head *head) -{ - struct kmmio_delayed_release *dr = container_of( - head, - struct kmmio_delayed_release, - rcu); - struct kmmio_fault_page *f = dr->release_list; - while (f) { - struct kmmio_fault_page *next = f->release_next; - BUG_ON(f->count); - kfree(f); - f = next; - } - kfree(dr); -} - -static void remove_kmmio_fault_pages(struct rcu_head *head) -{ - struct kmmio_delayed_release *dr = - container_of(head, struct kmmio_delayed_release, rcu); - struct kmmio_fault_page *f = dr->release_list; - struct kmmio_fault_page **prevp = &dr->release_list; - unsigned long flags; - - spin_lock_irqsave(&kmmio_lock, flags); - while (f) { - if (!f->count) { - list_del_rcu(&f->list); - prevp = &f->release_next; - } else { - *prevp = f->release_next; - f->release_next = NULL; - f->scheduled_for_release = false; - } - f = *prevp; - } - spin_unlock_irqrestore(&kmmio_lock, flags); - - /* This is the real RCU destroy call. */ - call_rcu(&dr->rcu, rcu_free_kmmio_fault_pages); -} - -/* - * Remove a kmmio probe. You have to synchronize_rcu() before you can be - * sure that the callbacks will not be called anymore. Only after that - * you may actually release your struct kmmio_probe. - * - * Unregistering a kmmio fault page has three steps: - * 1. release_kmmio_fault_page() - * Disarm the page, wait a grace period to let all faults finish. - * 2. remove_kmmio_fault_pages() - * Remove the pages from kmmio_page_table. - * 3. rcu_free_kmmio_fault_pages() - * Actually free the kmmio_fault_page structs as with RCU. - */ -void unregister_kmmio_probe(struct kmmio_probe *p) -{ - unsigned long flags; - unsigned long size = 0; - const unsigned long size_lim = p->len + (p->addr & ~PAGE_MASK); - struct kmmio_fault_page *release_list = NULL; - struct kmmio_delayed_release *drelease; - - spin_lock_irqsave(&kmmio_lock, flags); - while (size < size_lim) { - release_kmmio_fault_page(p->addr + size, &release_list); - size += PAGE_SIZE; - } - list_del_rcu(&p->list); - kmmio_count--; - spin_unlock_irqrestore(&kmmio_lock, flags); - - if (!release_list) - return; - - drelease = kmalloc(sizeof(*drelease), GFP_ATOMIC); - if (!drelease) { - pr_crit("leaking kmmio_fault_page objects.\n"); - return; - } - drelease->release_list = release_list; - - /* - * This is not really RCU here. We have just disarmed a set of - * pages so that they cannot trigger page faults anymore. However, - * we cannot remove the pages from kmmio_page_table, - * because a probe hit might be in flight on another CPU. The - * pages are collected into a list, and they will be removed from - * kmmio_page_table when it is certain that no probe hit related to - * these pages can be in flight. RCU grace period sounds like a - * good choice. - * - * If we removed the pages too early, kmmio page fault handler might - * not find the respective kmmio_fault_page and determine it's not - * a kmmio fault, when it actually is. This would lead to madness. - */ - call_rcu(&drelease->rcu, remove_kmmio_fault_pages); -} -EXPORT_SYMBOL(unregister_kmmio_probe); - -static int -kmmio_die_notifier(struct notifier_block *nb, unsigned long val, void *args) -{ - struct die_args *arg = args; - unsigned long* dr6_p = (unsigned long *)ERR_PTR(arg->err); - - if (val == DIE_DEBUG && (*dr6_p & DR_STEP)) - if (post_kmmio_handler(*dr6_p, arg->regs) == 1) { - /* - * Reset the BS bit in dr6 (pointed by args->err) to - * denote completion of processing - */ - *dr6_p &= ~DR_STEP; - return NOTIFY_STOP; - } - - return NOTIFY_DONE; -} - -static struct notifier_block nb_die = { - .notifier_call = kmmio_die_notifier -}; - -int kmmio_init(void) -{ - int i; - - for (i = 0; i < KMMIO_PAGE_TABLE_SIZE; i++) - INIT_LIST_HEAD(&kmmio_page_table[i]); - - return register_die_notifier(&nb_die); -} - -void kmmio_cleanup(void) -{ - int i; - - unregister_die_notifier(&nb_die); - for (i = 0; i < KMMIO_PAGE_TABLE_SIZE; i++) { - WARN_ONCE(!list_empty(&kmmio_page_table[i]), - KERN_ERR "kmmio_page_table not empty at cleanup, any further tracing will leak memory.\n"); - } -} |