Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 1 | /* Support for MMIO probes. |
| 2 | * Benfit many code from kprobes |
| 3 | * (C) 2002 Louis Zhuang <louis.zhuang@intel.com>. |
| 4 | * 2007 Alexander Eichner |
| 5 | * 2008 Pekka Paalanen <pq@iki.fi> |
| 6 | */ |
| 7 | |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 8 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| 9 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 10 | #include <linux/list.h> |
Ingo Molnar | 668a6c3 | 2008-05-19 13:35:24 +0200 | [diff] [blame] | 11 | #include <linux/rculist.h> |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 12 | #include <linux/spinlock.h> |
| 13 | #include <linux/hash.h> |
| 14 | #include <linux/init.h> |
| 15 | #include <linux/module.h> |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 16 | #include <linux/kernel.h> |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 17 | #include <linux/uaccess.h> |
| 18 | #include <linux/ptrace.h> |
| 19 | #include <linux/preempt.h> |
Pekka Paalanen | f513638 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 20 | #include <linux/percpu.h> |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 21 | #include <linux/kdebug.h> |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 22 | #include <linux/mutex.h> |
Pekka Paalanen | 970e6fa | 2008-05-12 21:21:03 +0200 | [diff] [blame] | 23 | #include <linux/io.h> |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 24 | #include <asm/cacheflush.h> |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 25 | #include <asm/tlbflush.h> |
Pekka Paalanen | 970e6fa | 2008-05-12 21:21:03 +0200 | [diff] [blame] | 26 | #include <linux/errno.h> |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 27 | #include <asm/debugreg.h> |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 28 | #include <linux/mmiotrace.h> |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 29 | |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 30 | #define KMMIO_PAGE_HASH_BITS 4 |
| 31 | #define KMMIO_PAGE_TABLE_SIZE (1 << KMMIO_PAGE_HASH_BITS) |
| 32 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 33 | struct kmmio_fault_page { |
| 34 | struct list_head list; |
| 35 | struct kmmio_fault_page *release_next; |
| 36 | unsigned long page; /* location of the fault page */ |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 37 | pteval_t old_presence; /* page presence prior to arming */ |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 38 | bool armed; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 39 | |
| 40 | /* |
| 41 | * Number of times this page has been registered as a part |
| 42 | * of a probe. If zero, page is disarmed and this may be freed. |
Pekka Paalanen | 340430c | 2009-02-24 21:44:15 +0200 | [diff] [blame] | 43 | * Used only by writers (RCU) and post_kmmio_handler(). |
| 44 | * Protected by kmmio_lock, when linked into kmmio_page_table. |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 45 | */ |
| 46 | int count; |
| 47 | }; |
| 48 | |
| 49 | struct kmmio_delayed_release { |
| 50 | struct rcu_head rcu; |
| 51 | struct kmmio_fault_page *release_list; |
| 52 | }; |
| 53 | |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 54 | struct kmmio_context { |
| 55 | struct kmmio_fault_page *fpage; |
| 56 | struct kmmio_probe *probe; |
| 57 | unsigned long saved_flags; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 58 | unsigned long addr; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 59 | int active; |
| 60 | }; |
| 61 | |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 62 | static DEFINE_SPINLOCK(kmmio_lock); |
| 63 | |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 64 | /* Protected by kmmio_lock */ |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 65 | unsigned int kmmio_count; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 66 | |
| 67 | /* Read-protected by RCU, write-protected by kmmio_lock. */ |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 68 | static struct list_head kmmio_page_table[KMMIO_PAGE_TABLE_SIZE]; |
| 69 | static LIST_HEAD(kmmio_probes); |
| 70 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 71 | static struct list_head *kmmio_page_list(unsigned long page) |
| 72 | { |
| 73 | return &kmmio_page_table[hash_long(page, KMMIO_PAGE_HASH_BITS)]; |
| 74 | } |
| 75 | |
Pekka Paalanen | f513638 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 76 | /* Accessed per-cpu */ |
| 77 | static DEFINE_PER_CPU(struct kmmio_context, kmmio_ctx); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 78 | |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 79 | /* |
| 80 | * this is basically a dynamic stabbing problem: |
| 81 | * Could use the existing prio tree code or |
| 82 | * Possible better implementations: |
| 83 | * The Interval Skip List: A Data Structure for Finding All Intervals That |
| 84 | * Overlap a Point (might be simple) |
| 85 | * Space Efficient Dynamic Stabbing with Fast Queries - Mikkel Thorup |
| 86 | */ |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 87 | /* Get the kmmio at this addr (if any). You must be holding RCU read lock. */ |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 88 | static struct kmmio_probe *get_kmmio_probe(unsigned long addr) |
| 89 | { |
| 90 | struct kmmio_probe *p; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 91 | list_for_each_entry_rcu(p, &kmmio_probes, list) { |
Stuart Bennett | 33015c8 | 2009-04-28 20:17:48 +0100 | [diff] [blame] | 92 | if (addr >= p->addr && addr < (p->addr + p->len)) |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 93 | return p; |
| 94 | } |
| 95 | return NULL; |
| 96 | } |
| 97 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 98 | /* You must be holding RCU read lock. */ |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 99 | static struct kmmio_fault_page *get_kmmio_fault_page(unsigned long page) |
| 100 | { |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 101 | struct list_head *head; |
Stuart Bennett | 0492e1b | 2009-04-28 20:17:49 +0100 | [diff] [blame] | 102 | struct kmmio_fault_page *f; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 103 | |
| 104 | page &= PAGE_MASK; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 105 | head = kmmio_page_list(page); |
Stuart Bennett | 0492e1b | 2009-04-28 20:17:49 +0100 | [diff] [blame] | 106 | list_for_each_entry_rcu(f, head, list) { |
| 107 | if (f->page == page) |
| 108 | return f; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 109 | } |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 110 | return NULL; |
| 111 | } |
| 112 | |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 113 | static void clear_pmd_presence(pmd_t *pmd, bool clear, pmdval_t *old) |
Pekka Paalanen | 0b700a6 | 2009-03-01 16:12:48 +0200 | [diff] [blame] | 114 | { |
| 115 | pmdval_t v = pmd_val(*pmd); |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 116 | if (clear) { |
| 117 | *old = v & _PAGE_PRESENT; |
| 118 | v &= ~_PAGE_PRESENT; |
| 119 | } else /* presume this has been called with clear==true previously */ |
| 120 | v |= *old; |
Pekka Paalanen | 0b700a6 | 2009-03-01 16:12:48 +0200 | [diff] [blame] | 121 | set_pmd(pmd, __pmd(v)); |
| 122 | } |
| 123 | |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 124 | static void clear_pte_presence(pte_t *pte, bool clear, pteval_t *old) |
Pekka Paalanen | 0b700a6 | 2009-03-01 16:12:48 +0200 | [diff] [blame] | 125 | { |
| 126 | pteval_t v = pte_val(*pte); |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 127 | if (clear) { |
| 128 | *old = v & _PAGE_PRESENT; |
| 129 | v &= ~_PAGE_PRESENT; |
| 130 | } else /* presume this has been called with clear==true previously */ |
| 131 | v |= *old; |
Pekka Paalanen | 0b700a6 | 2009-03-01 16:12:48 +0200 | [diff] [blame] | 132 | set_pte_atomic(pte, __pte(v)); |
| 133 | } |
| 134 | |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 135 | static int clear_page_presence(struct kmmio_fault_page *f, bool clear) |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 136 | { |
Pekka Paalanen | 790e2a2 | 2008-05-12 21:21:14 +0200 | [diff] [blame] | 137 | unsigned int level; |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 138 | pte_t *pte = lookup_address(f->page, &level); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 139 | |
Pekka Paalanen | 75bb883 | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 140 | if (!pte) { |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 141 | pr_err("no pte for page 0x%08lx\n", f->page); |
Stuart Bennett | e9d54ca | 2009-01-30 17:38:59 +0000 | [diff] [blame] | 142 | return -1; |
Pekka Paalanen | 75bb883 | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 143 | } |
| 144 | |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 145 | switch (level) { |
| 146 | case PG_LEVEL_2M: |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 147 | clear_pmd_presence((pmd_t *)pte, clear, &f->old_presence); |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 148 | break; |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 149 | case PG_LEVEL_4K: |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 150 | clear_pte_presence(pte, clear, &f->old_presence); |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 151 | break; |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 152 | default: |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 153 | pr_err("unexpected page level 0x%x.\n", level); |
Stuart Bennett | e9d54ca | 2009-01-30 17:38:59 +0000 | [diff] [blame] | 154 | return -1; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 155 | } |
| 156 | |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 157 | __flush_tlb_one(f->page); |
Stuart Bennett | e9d54ca | 2009-01-30 17:38:59 +0000 | [diff] [blame] | 158 | return 0; |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 159 | } |
Pekka Paalanen | 75bb883 | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 160 | |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 161 | /* |
| 162 | * Mark the given page as not present. Access to it will trigger a fault. |
| 163 | * |
| 164 | * Struct kmmio_fault_page is protected by RCU and kmmio_lock, but the |
| 165 | * protection is ignored here. RCU read lock is assumed held, so the struct |
| 166 | * will not disappear unexpectedly. Furthermore, the caller must guarantee, |
| 167 | * that double arming the same virtual address (page) cannot occur. |
| 168 | * |
| 169 | * Double disarming on the other hand is allowed, and may occur when a fault |
| 170 | * and mmiotrace shutdown happen simultaneously. |
| 171 | */ |
| 172 | static int arm_kmmio_fault_page(struct kmmio_fault_page *f) |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 173 | { |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 174 | int ret; |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 175 | WARN_ONCE(f->armed, KERN_ERR pr_fmt("kmmio page already armed.\n")); |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 176 | if (f->armed) { |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 177 | pr_warning("double-arm: page 0x%08lx, ref %d, old %d\n", |
| 178 | f->page, f->count, !!f->old_presence); |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 179 | } |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 180 | ret = clear_page_presence(f, true); |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 181 | WARN_ONCE(ret < 0, KERN_ERR pr_fmt("arming 0x%08lx failed.\n"), |
| 182 | f->page); |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 183 | f->armed = true; |
Stuart Bennett | e9d54ca | 2009-01-30 17:38:59 +0000 | [diff] [blame] | 184 | return ret; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 185 | } |
| 186 | |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 187 | /** Restore the given page to saved presence state. */ |
| 188 | static void disarm_kmmio_fault_page(struct kmmio_fault_page *f) |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 189 | { |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 190 | int ret = clear_page_presence(f, false); |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 191 | WARN_ONCE(ret < 0, |
| 192 | KERN_ERR "kmmio disarming 0x%08lx failed.\n", f->page); |
| 193 | f->armed = false; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 194 | } |
| 195 | |
| 196 | /* |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 197 | * This is being called from do_page_fault(). |
| 198 | * |
| 199 | * We may be in an interrupt or a critical section. Also prefecthing may |
| 200 | * trigger a page fault. We may be in the middle of process switch. |
| 201 | * We cannot take any locks, because we could be executing especially |
| 202 | * within a kmmio critical section. |
| 203 | * |
| 204 | * Local interrupts are disabled, so preemption cannot happen. |
| 205 | * Do not enable interrupts, do not sleep, and watch out for other CPUs. |
| 206 | */ |
| 207 | /* |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 208 | * Interrupts are disabled on entry as trap3 is an interrupt gate |
André Goddard Rosa | af901ca | 2009-11-14 13:09:05 -0200 | [diff] [blame] | 209 | * and they remain disabled throughout this function. |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 210 | */ |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 211 | int kmmio_handler(struct pt_regs *regs, unsigned long addr) |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 212 | { |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 213 | struct kmmio_context *ctx; |
| 214 | struct kmmio_fault_page *faultpage; |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 215 | int ret = 0; /* default to fault not handled */ |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 216 | |
| 217 | /* |
| 218 | * Preemption is now disabled to prevent process switch during |
| 219 | * single stepping. We can only handle one active kmmio trace |
| 220 | * per cpu, so ensure that we finish it before something else |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 221 | * gets to run. We also hold the RCU read lock over single |
| 222 | * stepping to avoid looking up the probe and kmmio_fault_page |
| 223 | * again. |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 224 | */ |
| 225 | preempt_disable(); |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 226 | rcu_read_lock(); |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 227 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 228 | faultpage = get_kmmio_fault_page(addr); |
| 229 | if (!faultpage) { |
| 230 | /* |
| 231 | * Either this page fault is not caused by kmmio, or |
| 232 | * another CPU just pulled the kmmio probe from under |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 233 | * our feet. The latter case should not be possible. |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 234 | */ |
| 235 | goto no_kmmio; |
| 236 | } |
| 237 | |
| 238 | ctx = &get_cpu_var(kmmio_ctx); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 239 | if (ctx->active) { |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 240 | if (addr == ctx->addr) { |
| 241 | /* |
Stuart Bennett | 3e39aa1 | 2009-02-05 11:02:02 +0000 | [diff] [blame] | 242 | * A second fault on the same page means some other |
| 243 | * condition needs handling by do_page_fault(), the |
| 244 | * page really not being present is the most common. |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 245 | */ |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 246 | pr_debug("secondary hit for 0x%08lx CPU %d.\n", |
| 247 | addr, smp_processor_id()); |
Stuart Bennett | 3e39aa1 | 2009-02-05 11:02:02 +0000 | [diff] [blame] | 248 | |
| 249 | if (!faultpage->old_presence) |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 250 | pr_info("unexpected secondary hit for address 0x%08lx on CPU %d.\n", |
| 251 | addr, smp_processor_id()); |
Stuart Bennett | 3e39aa1 | 2009-02-05 11:02:02 +0000 | [diff] [blame] | 252 | } else { |
| 253 | /* |
| 254 | * Prevent overwriting already in-flight context. |
| 255 | * This should not happen, let's hope disarming at |
| 256 | * least prevents a panic. |
| 257 | */ |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 258 | pr_emerg("recursive probe hit on CPU %d, for address 0x%08lx. Ignoring.\n", |
| 259 | smp_processor_id(), addr); |
| 260 | pr_emerg("previous hit was at 0x%08lx.\n", ctx->addr); |
Stuart Bennett | 3e39aa1 | 2009-02-05 11:02:02 +0000 | [diff] [blame] | 261 | disarm_kmmio_fault_page(faultpage); |
| 262 | } |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 263 | goto no_kmmio_ctx; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 264 | } |
| 265 | ctx->active++; |
| 266 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 267 | ctx->fpage = faultpage; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 268 | ctx->probe = get_kmmio_probe(addr); |
Ingo Molnar | 4902316 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 269 | ctx->saved_flags = (regs->flags & (X86_EFLAGS_TF | X86_EFLAGS_IF)); |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 270 | ctx->addr = addr; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 271 | |
| 272 | if (ctx->probe && ctx->probe->pre_handler) |
| 273 | ctx->probe->pre_handler(ctx->probe, regs, addr); |
| 274 | |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 275 | /* |
| 276 | * Enable single-stepping and disable interrupts for the faulting |
| 277 | * context. Local interrupts must not get enabled during stepping. |
| 278 | */ |
Ingo Molnar | 4902316 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 279 | regs->flags |= X86_EFLAGS_TF; |
| 280 | regs->flags &= ~X86_EFLAGS_IF; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 281 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 282 | /* Now we set present bit in PTE and single step. */ |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 283 | disarm_kmmio_fault_page(ctx->fpage); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 284 | |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 285 | /* |
| 286 | * If another cpu accesses the same page while we are stepping, |
| 287 | * the access will not be caught. It will simply succeed and the |
| 288 | * only downside is we lose the event. If this becomes a problem, |
| 289 | * the user should drop to single cpu before tracing. |
| 290 | */ |
| 291 | |
Pekka Paalanen | f513638 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 292 | put_cpu_var(kmmio_ctx); |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 293 | return 1; /* fault handled */ |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 294 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 295 | no_kmmio_ctx: |
Pekka Paalanen | f513638 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 296 | put_cpu_var(kmmio_ctx); |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 297 | no_kmmio: |
| 298 | rcu_read_unlock(); |
| 299 | preempt_enable_no_resched(); |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 300 | return ret; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 301 | } |
| 302 | |
| 303 | /* |
| 304 | * Interrupts are disabled on entry as trap1 is an interrupt gate |
André Goddard Rosa | af901ca | 2009-11-14 13:09:05 -0200 | [diff] [blame] | 305 | * and they remain disabled throughout this function. |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 306 | * This must always get called as the pair to kmmio_handler(). |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 307 | */ |
| 308 | static int post_kmmio_handler(unsigned long condition, struct pt_regs *regs) |
| 309 | { |
Pekka Paalanen | f513638 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 310 | int ret = 0; |
| 311 | struct kmmio_context *ctx = &get_cpu_var(kmmio_ctx); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 312 | |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 313 | if (!ctx->active) { |
Stuart Bennett | 0f9a623 | 2009-04-28 20:17:51 +0100 | [diff] [blame] | 314 | /* |
| 315 | * debug traps without an active context are due to either |
| 316 | * something external causing them (f.e. using a debugger while |
| 317 | * mmio tracing enabled), or erroneous behaviour |
| 318 | */ |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 319 | pr_warning("unexpected debug trap on CPU %d.\n", |
| 320 | smp_processor_id()); |
Pekka Paalanen | f513638 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 321 | goto out; |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 322 | } |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 323 | |
| 324 | if (ctx->probe && ctx->probe->post_handler) |
| 325 | ctx->probe->post_handler(ctx->probe, condition, regs); |
| 326 | |
Pekka Paalanen | 340430c | 2009-02-24 21:44:15 +0200 | [diff] [blame] | 327 | /* Prevent racing against release_kmmio_fault_page(). */ |
| 328 | spin_lock(&kmmio_lock); |
| 329 | if (ctx->fpage->count) |
| 330 | arm_kmmio_fault_page(ctx->fpage); |
| 331 | spin_unlock(&kmmio_lock); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 332 | |
Ingo Molnar | 4902316 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 333 | regs->flags &= ~X86_EFLAGS_TF; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 334 | regs->flags |= ctx->saved_flags; |
| 335 | |
| 336 | /* These were acquired in kmmio_handler(). */ |
| 337 | ctx->active--; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 338 | BUG_ON(ctx->active); |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 339 | rcu_read_unlock(); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 340 | preempt_enable_no_resched(); |
| 341 | |
| 342 | /* |
| 343 | * if somebody else is singlestepping across a probe point, flags |
| 344 | * will have TF set, in which case, continue the remaining processing |
| 345 | * of do_debug, as if this is not a probe hit. |
| 346 | */ |
Ingo Molnar | 4902316 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 347 | if (!(regs->flags & X86_EFLAGS_TF)) |
Pekka Paalanen | f513638 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 348 | ret = 1; |
Pekka Paalanen | f513638 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 349 | out: |
| 350 | put_cpu_var(kmmio_ctx); |
| 351 | return ret; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 352 | } |
| 353 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 354 | /* You must be holding kmmio_lock. */ |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 355 | static int add_kmmio_fault_page(unsigned long page) |
| 356 | { |
| 357 | struct kmmio_fault_page *f; |
| 358 | |
| 359 | page &= PAGE_MASK; |
| 360 | f = get_kmmio_fault_page(page); |
| 361 | if (f) { |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 362 | if (!f->count) |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 363 | arm_kmmio_fault_page(f); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 364 | f->count++; |
| 365 | return 0; |
| 366 | } |
| 367 | |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 368 | f = kzalloc(sizeof(*f), GFP_ATOMIC); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 369 | if (!f) |
| 370 | return -1; |
| 371 | |
| 372 | f->count = 1; |
| 373 | f->page = page; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 374 | |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 375 | if (arm_kmmio_fault_page(f)) { |
Stuart Bennett | e9d54ca | 2009-01-30 17:38:59 +0000 | [diff] [blame] | 376 | kfree(f); |
| 377 | return -1; |
| 378 | } |
| 379 | |
| 380 | list_add_rcu(&f->list, kmmio_page_list(f->page)); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 381 | |
| 382 | return 0; |
| 383 | } |
| 384 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 385 | /* You must be holding kmmio_lock. */ |
| 386 | static void release_kmmio_fault_page(unsigned long page, |
| 387 | struct kmmio_fault_page **release_list) |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 388 | { |
| 389 | struct kmmio_fault_page *f; |
| 390 | |
| 391 | page &= PAGE_MASK; |
| 392 | f = get_kmmio_fault_page(page); |
| 393 | if (!f) |
| 394 | return; |
| 395 | |
| 396 | f->count--; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 397 | BUG_ON(f->count < 0); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 398 | if (!f->count) { |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 399 | disarm_kmmio_fault_page(f); |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 400 | f->release_next = *release_list; |
| 401 | *release_list = f; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 402 | } |
| 403 | } |
| 404 | |
Pekka Paalanen | 87e547f | 2008-05-12 21:21:03 +0200 | [diff] [blame] | 405 | /* |
| 406 | * With page-unaligned ioremaps, one or two armed pages may contain |
| 407 | * addresses from outside the intended mapping. Events for these addresses |
| 408 | * are currently silently dropped. The events may result only from programming |
| 409 | * mistakes by accessing addresses before the beginning or past the end of a |
| 410 | * mapping. |
| 411 | */ |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 412 | int register_kmmio_probe(struct kmmio_probe *p) |
| 413 | { |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 414 | unsigned long flags; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 415 | int ret = 0; |
| 416 | unsigned long size = 0; |
Pekka Paalanen | 87e547f | 2008-05-12 21:21:03 +0200 | [diff] [blame] | 417 | const unsigned long size_lim = p->len + (p->addr & ~PAGE_MASK); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 418 | |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 419 | spin_lock_irqsave(&kmmio_lock, flags); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 420 | if (get_kmmio_probe(p->addr)) { |
| 421 | ret = -EEXIST; |
| 422 | goto out; |
| 423 | } |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 424 | kmmio_count++; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 425 | list_add_rcu(&p->list, &kmmio_probes); |
Pekka Paalanen | 87e547f | 2008-05-12 21:21:03 +0200 | [diff] [blame] | 426 | while (size < size_lim) { |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 427 | if (add_kmmio_fault_page(p->addr + size)) |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 428 | pr_err("Unable to set page fault.\n"); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 429 | size += PAGE_SIZE; |
| 430 | } |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 431 | out: |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 432 | spin_unlock_irqrestore(&kmmio_lock, flags); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 433 | /* |
| 434 | * XXX: What should I do here? |
| 435 | * Here was a call to global_flush_tlb(), but it does not exist |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 436 | * anymore. It seems it's not needed after all. |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 437 | */ |
| 438 | return ret; |
| 439 | } |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 440 | EXPORT_SYMBOL(register_kmmio_probe); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 441 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 442 | static void rcu_free_kmmio_fault_pages(struct rcu_head *head) |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 443 | { |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 444 | struct kmmio_delayed_release *dr = container_of( |
| 445 | head, |
| 446 | struct kmmio_delayed_release, |
| 447 | rcu); |
Stuart Bennett | 0492e1b | 2009-04-28 20:17:49 +0100 | [diff] [blame] | 448 | struct kmmio_fault_page *f = dr->release_list; |
| 449 | while (f) { |
| 450 | struct kmmio_fault_page *next = f->release_next; |
| 451 | BUG_ON(f->count); |
| 452 | kfree(f); |
| 453 | f = next; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 454 | } |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 455 | kfree(dr); |
| 456 | } |
| 457 | |
| 458 | static void remove_kmmio_fault_pages(struct rcu_head *head) |
| 459 | { |
Stuart Bennett | d0fc63f | 2009-03-08 20:21:35 +0200 | [diff] [blame] | 460 | struct kmmio_delayed_release *dr = |
| 461 | container_of(head, struct kmmio_delayed_release, rcu); |
Stuart Bennett | 0492e1b | 2009-04-28 20:17:49 +0100 | [diff] [blame] | 462 | struct kmmio_fault_page *f = dr->release_list; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 463 | struct kmmio_fault_page **prevp = &dr->release_list; |
| 464 | unsigned long flags; |
Stuart Bennett | d0fc63f | 2009-03-08 20:21:35 +0200 | [diff] [blame] | 465 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 466 | spin_lock_irqsave(&kmmio_lock, flags); |
Stuart Bennett | 0492e1b | 2009-04-28 20:17:49 +0100 | [diff] [blame] | 467 | while (f) { |
| 468 | if (!f->count) { |
| 469 | list_del_rcu(&f->list); |
| 470 | prevp = &f->release_next; |
Stuart Bennett | d0fc63f | 2009-03-08 20:21:35 +0200 | [diff] [blame] | 471 | } else { |
Stuart Bennett | 0492e1b | 2009-04-28 20:17:49 +0100 | [diff] [blame] | 472 | *prevp = f->release_next; |
Stuart Bennett | d0fc63f | 2009-03-08 20:21:35 +0200 | [diff] [blame] | 473 | } |
Stuart Bennett | 0492e1b | 2009-04-28 20:17:49 +0100 | [diff] [blame] | 474 | f = f->release_next; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 475 | } |
| 476 | spin_unlock_irqrestore(&kmmio_lock, flags); |
Stuart Bennett | d0fc63f | 2009-03-08 20:21:35 +0200 | [diff] [blame] | 477 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 478 | /* This is the real RCU destroy call. */ |
| 479 | call_rcu(&dr->rcu, rcu_free_kmmio_fault_pages); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 480 | } |
| 481 | |
| 482 | /* |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 483 | * Remove a kmmio probe. You have to synchronize_rcu() before you can be |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 484 | * sure that the callbacks will not be called anymore. Only after that |
| 485 | * you may actually release your struct kmmio_probe. |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 486 | * |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 487 | * Unregistering a kmmio fault page has three steps: |
| 488 | * 1. release_kmmio_fault_page() |
| 489 | * Disarm the page, wait a grace period to let all faults finish. |
| 490 | * 2. remove_kmmio_fault_pages() |
| 491 | * Remove the pages from kmmio_page_table. |
| 492 | * 3. rcu_free_kmmio_fault_pages() |
Shaun Patterson | 8055039 | 2009-12-05 10:41:34 -0500 | [diff] [blame] | 493 | * Actually free the kmmio_fault_page structs as with RCU. |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 494 | */ |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 495 | void unregister_kmmio_probe(struct kmmio_probe *p) |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 496 | { |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 497 | unsigned long flags; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 498 | unsigned long size = 0; |
Pekka Paalanen | 87e547f | 2008-05-12 21:21:03 +0200 | [diff] [blame] | 499 | const unsigned long size_lim = p->len + (p->addr & ~PAGE_MASK); |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 500 | struct kmmio_fault_page *release_list = NULL; |
| 501 | struct kmmio_delayed_release *drelease; |
| 502 | |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 503 | spin_lock_irqsave(&kmmio_lock, flags); |
Pekka Paalanen | 87e547f | 2008-05-12 21:21:03 +0200 | [diff] [blame] | 504 | while (size < size_lim) { |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 505 | release_kmmio_fault_page(p->addr + size, &release_list); |
| 506 | size += PAGE_SIZE; |
| 507 | } |
| 508 | list_del_rcu(&p->list); |
| 509 | kmmio_count--; |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 510 | spin_unlock_irqrestore(&kmmio_lock, flags); |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 511 | |
| 512 | drelease = kmalloc(sizeof(*drelease), GFP_ATOMIC); |
| 513 | if (!drelease) { |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 514 | pr_crit("leaking kmmio_fault_page objects.\n"); |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 515 | return; |
| 516 | } |
| 517 | drelease->release_list = release_list; |
| 518 | |
| 519 | /* |
| 520 | * This is not really RCU here. We have just disarmed a set of |
| 521 | * pages so that they cannot trigger page faults anymore. However, |
| 522 | * we cannot remove the pages from kmmio_page_table, |
| 523 | * because a probe hit might be in flight on another CPU. The |
| 524 | * pages are collected into a list, and they will be removed from |
| 525 | * kmmio_page_table when it is certain that no probe hit related to |
| 526 | * these pages can be in flight. RCU grace period sounds like a |
| 527 | * good choice. |
| 528 | * |
| 529 | * If we removed the pages too early, kmmio page fault handler might |
| 530 | * not find the respective kmmio_fault_page and determine it's not |
| 531 | * a kmmio fault, when it actually is. This would lead to madness. |
| 532 | */ |
| 533 | call_rcu(&drelease->rcu, remove_kmmio_fault_pages); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 534 | } |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 535 | EXPORT_SYMBOL(unregister_kmmio_probe); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 536 | |
Stuart Bennett | 0f9a623 | 2009-04-28 20:17:51 +0100 | [diff] [blame] | 537 | static int |
| 538 | kmmio_die_notifier(struct notifier_block *nb, unsigned long val, void *args) |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 539 | { |
| 540 | struct die_args *arg = args; |
Luca Barbieri | 0bb7a95 | 2010-01-16 10:39:30 +0100 | [diff] [blame^] | 541 | unsigned long* dr6_p = (unsigned long *)ERR_PTR(arg->err); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 542 | |
Luca Barbieri | 0bb7a95 | 2010-01-16 10:39:30 +0100 | [diff] [blame^] | 543 | if (val == DIE_DEBUG && (*dr6_p & DR_STEP)) |
| 544 | if (post_kmmio_handler(*dr6_p, arg->regs) == 1) { |
K.Prasad | 62edab9 | 2009-06-01 23:47:06 +0530 | [diff] [blame] | 545 | /* |
| 546 | * Reset the BS bit in dr6 (pointed by args->err) to |
| 547 | * denote completion of processing |
| 548 | */ |
Luca Barbieri | 0bb7a95 | 2010-01-16 10:39:30 +0100 | [diff] [blame^] | 549 | *dr6_p &= ~DR_STEP; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 550 | return NOTIFY_STOP; |
K.Prasad | 62edab9 | 2009-06-01 23:47:06 +0530 | [diff] [blame] | 551 | } |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 552 | |
| 553 | return NOTIFY_DONE; |
| 554 | } |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 555 | |
| 556 | static struct notifier_block nb_die = { |
| 557 | .notifier_call = kmmio_die_notifier |
| 558 | }; |
| 559 | |
Stuart Bennett | 0f9a623 | 2009-04-28 20:17:51 +0100 | [diff] [blame] | 560 | int kmmio_init(void) |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 561 | { |
| 562 | int i; |
Stuart Bennett | 0f9a623 | 2009-04-28 20:17:51 +0100 | [diff] [blame] | 563 | |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 564 | for (i = 0; i < KMMIO_PAGE_TABLE_SIZE; i++) |
| 565 | INIT_LIST_HEAD(&kmmio_page_table[i]); |
Stuart Bennett | 0f9a623 | 2009-04-28 20:17:51 +0100 | [diff] [blame] | 566 | |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 567 | return register_die_notifier(&nb_die); |
| 568 | } |
Stuart Bennett | 0f9a623 | 2009-04-28 20:17:51 +0100 | [diff] [blame] | 569 | |
| 570 | void kmmio_cleanup(void) |
| 571 | { |
| 572 | int i; |
| 573 | |
| 574 | unregister_die_notifier(&nb_die); |
| 575 | for (i = 0; i < KMMIO_PAGE_TABLE_SIZE; i++) { |
| 576 | WARN_ONCE(!list_empty(&kmmio_page_table[i]), |
| 577 | KERN_ERR "kmmio_page_table not empty at cleanup, any further tracing will leak memory.\n"); |
| 578 | } |
| 579 | } |