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> |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 24 | #include <linux/slab.h> |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 25 | #include <asm/cacheflush.h> |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 26 | #include <asm/tlbflush.h> |
Pekka Paalanen | 970e6fa | 2008-05-12 21:21:03 +0200 | [diff] [blame] | 27 | #include <linux/errno.h> |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 28 | #include <asm/debugreg.h> |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 29 | #include <linux/mmiotrace.h> |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 30 | |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 31 | #define KMMIO_PAGE_HASH_BITS 4 |
| 32 | #define KMMIO_PAGE_TABLE_SIZE (1 << KMMIO_PAGE_HASH_BITS) |
| 33 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 34 | struct kmmio_fault_page { |
| 35 | struct list_head list; |
| 36 | struct kmmio_fault_page *release_next; |
| 37 | unsigned long page; /* location of the fault page */ |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 38 | pteval_t old_presence; /* page presence prior to arming */ |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 39 | bool armed; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 40 | |
| 41 | /* |
| 42 | * Number of times this page has been registered as a part |
| 43 | * 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] | 44 | * Used only by writers (RCU) and post_kmmio_handler(). |
| 45 | * Protected by kmmio_lock, when linked into kmmio_page_table. |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 46 | */ |
| 47 | int count; |
Marcin Slusarz | 8b8f79b | 2010-06-13 23:56:54 +0200 | [diff] [blame^] | 48 | |
| 49 | bool scheduled_for_release; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 50 | }; |
| 51 | |
| 52 | struct kmmio_delayed_release { |
| 53 | struct rcu_head rcu; |
| 54 | struct kmmio_fault_page *release_list; |
| 55 | }; |
| 56 | |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 57 | struct kmmio_context { |
| 58 | struct kmmio_fault_page *fpage; |
| 59 | struct kmmio_probe *probe; |
| 60 | unsigned long saved_flags; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 61 | unsigned long addr; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 62 | int active; |
| 63 | }; |
| 64 | |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 65 | static DEFINE_SPINLOCK(kmmio_lock); |
| 66 | |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 67 | /* Protected by kmmio_lock */ |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 68 | unsigned int kmmio_count; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 69 | |
| 70 | /* Read-protected by RCU, write-protected by kmmio_lock. */ |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 71 | static struct list_head kmmio_page_table[KMMIO_PAGE_TABLE_SIZE]; |
| 72 | static LIST_HEAD(kmmio_probes); |
| 73 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 74 | static struct list_head *kmmio_page_list(unsigned long page) |
| 75 | { |
| 76 | return &kmmio_page_table[hash_long(page, KMMIO_PAGE_HASH_BITS)]; |
| 77 | } |
| 78 | |
Pekka Paalanen | f513638 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 79 | /* Accessed per-cpu */ |
| 80 | static DEFINE_PER_CPU(struct kmmio_context, kmmio_ctx); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 81 | |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 82 | /* |
| 83 | * this is basically a dynamic stabbing problem: |
| 84 | * Could use the existing prio tree code or |
| 85 | * Possible better implementations: |
| 86 | * The Interval Skip List: A Data Structure for Finding All Intervals That |
| 87 | * Overlap a Point (might be simple) |
| 88 | * Space Efficient Dynamic Stabbing with Fast Queries - Mikkel Thorup |
| 89 | */ |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 90 | /* 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] | 91 | static struct kmmio_probe *get_kmmio_probe(unsigned long addr) |
| 92 | { |
| 93 | struct kmmio_probe *p; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 94 | list_for_each_entry_rcu(p, &kmmio_probes, list) { |
Stuart Bennett | 33015c8 | 2009-04-28 20:17:48 +0100 | [diff] [blame] | 95 | if (addr >= p->addr && addr < (p->addr + p->len)) |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 96 | return p; |
| 97 | } |
| 98 | return NULL; |
| 99 | } |
| 100 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 101 | /* You must be holding RCU read lock. */ |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 102 | static struct kmmio_fault_page *get_kmmio_fault_page(unsigned long page) |
| 103 | { |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 104 | struct list_head *head; |
Stuart Bennett | 0492e1b | 2009-04-28 20:17:49 +0100 | [diff] [blame] | 105 | struct kmmio_fault_page *f; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 106 | |
| 107 | page &= PAGE_MASK; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 108 | head = kmmio_page_list(page); |
Stuart Bennett | 0492e1b | 2009-04-28 20:17:49 +0100 | [diff] [blame] | 109 | list_for_each_entry_rcu(f, head, list) { |
| 110 | if (f->page == page) |
| 111 | return f; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 112 | } |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 113 | return NULL; |
| 114 | } |
| 115 | |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 116 | 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] | 117 | { |
| 118 | pmdval_t v = pmd_val(*pmd); |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 119 | if (clear) { |
| 120 | *old = v & _PAGE_PRESENT; |
| 121 | v &= ~_PAGE_PRESENT; |
| 122 | } else /* presume this has been called with clear==true previously */ |
| 123 | v |= *old; |
Pekka Paalanen | 0b700a6 | 2009-03-01 16:12:48 +0200 | [diff] [blame] | 124 | set_pmd(pmd, __pmd(v)); |
| 125 | } |
| 126 | |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 127 | 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] | 128 | { |
| 129 | pteval_t v = pte_val(*pte); |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 130 | if (clear) { |
| 131 | *old = v & _PAGE_PRESENT; |
| 132 | v &= ~_PAGE_PRESENT; |
| 133 | } else /* presume this has been called with clear==true previously */ |
| 134 | v |= *old; |
Pekka Paalanen | 0b700a6 | 2009-03-01 16:12:48 +0200 | [diff] [blame] | 135 | set_pte_atomic(pte, __pte(v)); |
| 136 | } |
| 137 | |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 138 | static int clear_page_presence(struct kmmio_fault_page *f, bool clear) |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 139 | { |
Pekka Paalanen | 790e2a2 | 2008-05-12 21:21:14 +0200 | [diff] [blame] | 140 | unsigned int level; |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 141 | pte_t *pte = lookup_address(f->page, &level); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 142 | |
Pekka Paalanen | 75bb883 | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 143 | if (!pte) { |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 144 | pr_err("no pte for page 0x%08lx\n", f->page); |
Stuart Bennett | e9d54ca | 2009-01-30 17:38:59 +0000 | [diff] [blame] | 145 | return -1; |
Pekka Paalanen | 75bb883 | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 146 | } |
| 147 | |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 148 | switch (level) { |
| 149 | case PG_LEVEL_2M: |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 150 | clear_pmd_presence((pmd_t *)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 | case PG_LEVEL_4K: |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 153 | clear_pte_presence(pte, clear, &f->old_presence); |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 154 | break; |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 155 | default: |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 156 | pr_err("unexpected page level 0x%x.\n", level); |
Stuart Bennett | e9d54ca | 2009-01-30 17:38:59 +0000 | [diff] [blame] | 157 | return -1; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 158 | } |
| 159 | |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 160 | __flush_tlb_one(f->page); |
Stuart Bennett | e9d54ca | 2009-01-30 17:38:59 +0000 | [diff] [blame] | 161 | return 0; |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 162 | } |
Pekka Paalanen | 75bb883 | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 163 | |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 164 | /* |
| 165 | * Mark the given page as not present. Access to it will trigger a fault. |
| 166 | * |
| 167 | * Struct kmmio_fault_page is protected by RCU and kmmio_lock, but the |
| 168 | * protection is ignored here. RCU read lock is assumed held, so the struct |
| 169 | * will not disappear unexpectedly. Furthermore, the caller must guarantee, |
| 170 | * that double arming the same virtual address (page) cannot occur. |
| 171 | * |
| 172 | * Double disarming on the other hand is allowed, and may occur when a fault |
| 173 | * and mmiotrace shutdown happen simultaneously. |
| 174 | */ |
| 175 | static int arm_kmmio_fault_page(struct kmmio_fault_page *f) |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 176 | { |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 177 | int ret; |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 178 | 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] | 179 | if (f->armed) { |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 180 | pr_warning("double-arm: page 0x%08lx, ref %d, old %d\n", |
| 181 | f->page, f->count, !!f->old_presence); |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 182 | } |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 183 | ret = clear_page_presence(f, true); |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 184 | WARN_ONCE(ret < 0, KERN_ERR pr_fmt("arming 0x%08lx failed.\n"), |
| 185 | f->page); |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 186 | f->armed = true; |
Stuart Bennett | e9d54ca | 2009-01-30 17:38:59 +0000 | [diff] [blame] | 187 | return ret; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 188 | } |
| 189 | |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 190 | /** Restore the given page to saved presence state. */ |
| 191 | static void disarm_kmmio_fault_page(struct kmmio_fault_page *f) |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 192 | { |
Stuart Bennett | 46e91d0 | 2009-04-28 20:17:50 +0100 | [diff] [blame] | 193 | int ret = clear_page_presence(f, false); |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 194 | WARN_ONCE(ret < 0, |
| 195 | KERN_ERR "kmmio disarming 0x%08lx failed.\n", f->page); |
| 196 | f->armed = false; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 197 | } |
| 198 | |
| 199 | /* |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 200 | * This is being called from do_page_fault(). |
| 201 | * |
| 202 | * We may be in an interrupt or a critical section. Also prefecthing may |
| 203 | * trigger a page fault. We may be in the middle of process switch. |
| 204 | * We cannot take any locks, because we could be executing especially |
| 205 | * within a kmmio critical section. |
| 206 | * |
| 207 | * Local interrupts are disabled, so preemption cannot happen. |
| 208 | * Do not enable interrupts, do not sleep, and watch out for other CPUs. |
| 209 | */ |
| 210 | /* |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 211 | * Interrupts are disabled on entry as trap3 is an interrupt gate |
André Goddard Rosa | af901ca | 2009-11-14 13:09:05 -0200 | [diff] [blame] | 212 | * and they remain disabled throughout this function. |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 213 | */ |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 214 | int kmmio_handler(struct pt_regs *regs, unsigned long addr) |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 215 | { |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 216 | struct kmmio_context *ctx; |
| 217 | struct kmmio_fault_page *faultpage; |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 218 | int ret = 0; /* default to fault not handled */ |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 219 | |
| 220 | /* |
| 221 | * Preemption is now disabled to prevent process switch during |
| 222 | * single stepping. We can only handle one active kmmio trace |
| 223 | * per cpu, so ensure that we finish it before something else |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 224 | * gets to run. We also hold the RCU read lock over single |
| 225 | * stepping to avoid looking up the probe and kmmio_fault_page |
| 226 | * again. |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 227 | */ |
| 228 | preempt_disable(); |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 229 | rcu_read_lock(); |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 230 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 231 | faultpage = get_kmmio_fault_page(addr); |
| 232 | if (!faultpage) { |
| 233 | /* |
| 234 | * Either this page fault is not caused by kmmio, or |
| 235 | * another CPU just pulled the kmmio probe from under |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 236 | * our feet. The latter case should not be possible. |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 237 | */ |
| 238 | goto no_kmmio; |
| 239 | } |
| 240 | |
| 241 | ctx = &get_cpu_var(kmmio_ctx); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 242 | if (ctx->active) { |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 243 | if (addr == ctx->addr) { |
| 244 | /* |
Stuart Bennett | 3e39aa1 | 2009-02-05 11:02:02 +0000 | [diff] [blame] | 245 | * A second fault on the same page means some other |
| 246 | * condition needs handling by do_page_fault(), the |
| 247 | * page really not being present is the most common. |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 248 | */ |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 249 | pr_debug("secondary hit for 0x%08lx CPU %d.\n", |
| 250 | addr, smp_processor_id()); |
Stuart Bennett | 3e39aa1 | 2009-02-05 11:02:02 +0000 | [diff] [blame] | 251 | |
| 252 | if (!faultpage->old_presence) |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 253 | pr_info("unexpected secondary hit for address 0x%08lx on CPU %d.\n", |
| 254 | addr, smp_processor_id()); |
Stuart Bennett | 3e39aa1 | 2009-02-05 11:02:02 +0000 | [diff] [blame] | 255 | } else { |
| 256 | /* |
| 257 | * Prevent overwriting already in-flight context. |
| 258 | * This should not happen, let's hope disarming at |
| 259 | * least prevents a panic. |
| 260 | */ |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 261 | pr_emerg("recursive probe hit on CPU %d, for address 0x%08lx. Ignoring.\n", |
| 262 | smp_processor_id(), addr); |
| 263 | pr_emerg("previous hit was at 0x%08lx.\n", ctx->addr); |
Stuart Bennett | 3e39aa1 | 2009-02-05 11:02:02 +0000 | [diff] [blame] | 264 | disarm_kmmio_fault_page(faultpage); |
| 265 | } |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 266 | goto no_kmmio_ctx; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 267 | } |
| 268 | ctx->active++; |
| 269 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 270 | ctx->fpage = faultpage; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 271 | ctx->probe = get_kmmio_probe(addr); |
Ingo Molnar | 4902316 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 272 | ctx->saved_flags = (regs->flags & (X86_EFLAGS_TF | X86_EFLAGS_IF)); |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 273 | ctx->addr = addr; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 274 | |
| 275 | if (ctx->probe && ctx->probe->pre_handler) |
| 276 | ctx->probe->pre_handler(ctx->probe, regs, addr); |
| 277 | |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 278 | /* |
| 279 | * Enable single-stepping and disable interrupts for the faulting |
| 280 | * context. Local interrupts must not get enabled during stepping. |
| 281 | */ |
Ingo Molnar | 4902316 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 282 | regs->flags |= X86_EFLAGS_TF; |
| 283 | regs->flags &= ~X86_EFLAGS_IF; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 284 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 285 | /* Now we set present bit in PTE and single step. */ |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 286 | disarm_kmmio_fault_page(ctx->fpage); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 287 | |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 288 | /* |
| 289 | * If another cpu accesses the same page while we are stepping, |
| 290 | * the access will not be caught. It will simply succeed and the |
| 291 | * only downside is we lose the event. If this becomes a problem, |
| 292 | * the user should drop to single cpu before tracing. |
| 293 | */ |
| 294 | |
Pekka Paalanen | f513638 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 295 | put_cpu_var(kmmio_ctx); |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 296 | return 1; /* fault handled */ |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 297 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 298 | no_kmmio_ctx: |
Pekka Paalanen | f513638 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 299 | put_cpu_var(kmmio_ctx); |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 300 | no_kmmio: |
| 301 | rcu_read_unlock(); |
| 302 | preempt_enable_no_resched(); |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 303 | return ret; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 304 | } |
| 305 | |
| 306 | /* |
| 307 | * Interrupts are disabled on entry as trap1 is an interrupt gate |
André Goddard Rosa | af901ca | 2009-11-14 13:09:05 -0200 | [diff] [blame] | 308 | * and they remain disabled throughout this function. |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 309 | * This must always get called as the pair to kmmio_handler(). |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 310 | */ |
| 311 | static int post_kmmio_handler(unsigned long condition, struct pt_regs *regs) |
| 312 | { |
Pekka Paalanen | f513638 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 313 | int ret = 0; |
| 314 | struct kmmio_context *ctx = &get_cpu_var(kmmio_ctx); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 315 | |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 316 | if (!ctx->active) { |
Stuart Bennett | 0f9a623 | 2009-04-28 20:17:51 +0100 | [diff] [blame] | 317 | /* |
| 318 | * debug traps without an active context are due to either |
| 319 | * something external causing them (f.e. using a debugger while |
| 320 | * mmio tracing enabled), or erroneous behaviour |
| 321 | */ |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 322 | pr_warning("unexpected debug trap on CPU %d.\n", |
| 323 | smp_processor_id()); |
Pekka Paalanen | f513638 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 324 | goto out; |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 325 | } |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 326 | |
| 327 | if (ctx->probe && ctx->probe->post_handler) |
| 328 | ctx->probe->post_handler(ctx->probe, condition, regs); |
| 329 | |
Pekka Paalanen | 340430c | 2009-02-24 21:44:15 +0200 | [diff] [blame] | 330 | /* Prevent racing against release_kmmio_fault_page(). */ |
| 331 | spin_lock(&kmmio_lock); |
| 332 | if (ctx->fpage->count) |
| 333 | arm_kmmio_fault_page(ctx->fpage); |
| 334 | spin_unlock(&kmmio_lock); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 335 | |
Ingo Molnar | 4902316 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 336 | regs->flags &= ~X86_EFLAGS_TF; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 337 | regs->flags |= ctx->saved_flags; |
| 338 | |
| 339 | /* These were acquired in kmmio_handler(). */ |
| 340 | ctx->active--; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 341 | BUG_ON(ctx->active); |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 342 | rcu_read_unlock(); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 343 | preempt_enable_no_resched(); |
| 344 | |
| 345 | /* |
| 346 | * if somebody else is singlestepping across a probe point, flags |
| 347 | * will have TF set, in which case, continue the remaining processing |
| 348 | * of do_debug, as if this is not a probe hit. |
| 349 | */ |
Ingo Molnar | 4902316 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 350 | if (!(regs->flags & X86_EFLAGS_TF)) |
Pekka Paalanen | f513638 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 351 | ret = 1; |
Pekka Paalanen | f513638 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 352 | out: |
| 353 | put_cpu_var(kmmio_ctx); |
| 354 | return ret; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 355 | } |
| 356 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 357 | /* You must be holding kmmio_lock. */ |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 358 | static int add_kmmio_fault_page(unsigned long page) |
| 359 | { |
| 360 | struct kmmio_fault_page *f; |
| 361 | |
| 362 | page &= PAGE_MASK; |
| 363 | f = get_kmmio_fault_page(page); |
| 364 | if (f) { |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 365 | if (!f->count) |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 366 | arm_kmmio_fault_page(f); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 367 | f->count++; |
| 368 | return 0; |
| 369 | } |
| 370 | |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 371 | f = kzalloc(sizeof(*f), GFP_ATOMIC); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 372 | if (!f) |
| 373 | return -1; |
| 374 | |
| 375 | f->count = 1; |
| 376 | f->page = page; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 377 | |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 378 | if (arm_kmmio_fault_page(f)) { |
Stuart Bennett | e9d54ca | 2009-01-30 17:38:59 +0000 | [diff] [blame] | 379 | kfree(f); |
| 380 | return -1; |
| 381 | } |
| 382 | |
| 383 | list_add_rcu(&f->list, kmmio_page_list(f->page)); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 384 | |
| 385 | return 0; |
| 386 | } |
| 387 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 388 | /* You must be holding kmmio_lock. */ |
| 389 | static void release_kmmio_fault_page(unsigned long page, |
| 390 | struct kmmio_fault_page **release_list) |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 391 | { |
| 392 | struct kmmio_fault_page *f; |
| 393 | |
| 394 | page &= PAGE_MASK; |
| 395 | f = get_kmmio_fault_page(page); |
| 396 | if (!f) |
| 397 | return; |
| 398 | |
| 399 | f->count--; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 400 | BUG_ON(f->count < 0); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 401 | if (!f->count) { |
Pekka Paalanen | 5359b58 | 2009-03-01 16:11:58 +0200 | [diff] [blame] | 402 | disarm_kmmio_fault_page(f); |
Marcin Slusarz | 8b8f79b | 2010-06-13 23:56:54 +0200 | [diff] [blame^] | 403 | if (!f->scheduled_for_release) { |
| 404 | f->release_next = *release_list; |
| 405 | *release_list = f; |
| 406 | f->scheduled_for_release = true; |
| 407 | } |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 408 | } |
| 409 | } |
| 410 | |
Pekka Paalanen | 87e547f | 2008-05-12 21:21:03 +0200 | [diff] [blame] | 411 | /* |
| 412 | * With page-unaligned ioremaps, one or two armed pages may contain |
| 413 | * addresses from outside the intended mapping. Events for these addresses |
| 414 | * are currently silently dropped. The events may result only from programming |
| 415 | * mistakes by accessing addresses before the beginning or past the end of a |
| 416 | * mapping. |
| 417 | */ |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 418 | int register_kmmio_probe(struct kmmio_probe *p) |
| 419 | { |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 420 | unsigned long flags; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 421 | int ret = 0; |
| 422 | unsigned long size = 0; |
Pekka Paalanen | 87e547f | 2008-05-12 21:21:03 +0200 | [diff] [blame] | 423 | const unsigned long size_lim = p->len + (p->addr & ~PAGE_MASK); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 424 | |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 425 | spin_lock_irqsave(&kmmio_lock, flags); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 426 | if (get_kmmio_probe(p->addr)) { |
| 427 | ret = -EEXIST; |
| 428 | goto out; |
| 429 | } |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 430 | kmmio_count++; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 431 | list_add_rcu(&p->list, &kmmio_probes); |
Pekka Paalanen | 87e547f | 2008-05-12 21:21:03 +0200 | [diff] [blame] | 432 | while (size < size_lim) { |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 433 | if (add_kmmio_fault_page(p->addr + size)) |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 434 | pr_err("Unable to set page fault.\n"); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 435 | size += PAGE_SIZE; |
| 436 | } |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 437 | out: |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 438 | spin_unlock_irqrestore(&kmmio_lock, flags); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 439 | /* |
| 440 | * XXX: What should I do here? |
| 441 | * 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] | 442 | * anymore. It seems it's not needed after all. |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 443 | */ |
| 444 | return ret; |
| 445 | } |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 446 | EXPORT_SYMBOL(register_kmmio_probe); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 447 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 448 | static void rcu_free_kmmio_fault_pages(struct rcu_head *head) |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 449 | { |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 450 | struct kmmio_delayed_release *dr = container_of( |
| 451 | head, |
| 452 | struct kmmio_delayed_release, |
| 453 | rcu); |
Stuart Bennett | 0492e1b | 2009-04-28 20:17:49 +0100 | [diff] [blame] | 454 | struct kmmio_fault_page *f = dr->release_list; |
| 455 | while (f) { |
| 456 | struct kmmio_fault_page *next = f->release_next; |
| 457 | BUG_ON(f->count); |
| 458 | kfree(f); |
| 459 | f = next; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 460 | } |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 461 | kfree(dr); |
| 462 | } |
| 463 | |
| 464 | static void remove_kmmio_fault_pages(struct rcu_head *head) |
| 465 | { |
Stuart Bennett | d0fc63f | 2009-03-08 20:21:35 +0200 | [diff] [blame] | 466 | struct kmmio_delayed_release *dr = |
| 467 | container_of(head, struct kmmio_delayed_release, rcu); |
Stuart Bennett | 0492e1b | 2009-04-28 20:17:49 +0100 | [diff] [blame] | 468 | struct kmmio_fault_page *f = dr->release_list; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 469 | struct kmmio_fault_page **prevp = &dr->release_list; |
| 470 | unsigned long flags; |
Stuart Bennett | d0fc63f | 2009-03-08 20:21:35 +0200 | [diff] [blame] | 471 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 472 | spin_lock_irqsave(&kmmio_lock, flags); |
Stuart Bennett | 0492e1b | 2009-04-28 20:17:49 +0100 | [diff] [blame] | 473 | while (f) { |
| 474 | if (!f->count) { |
| 475 | list_del_rcu(&f->list); |
| 476 | prevp = &f->release_next; |
Stuart Bennett | d0fc63f | 2009-03-08 20:21:35 +0200 | [diff] [blame] | 477 | } else { |
Stuart Bennett | 0492e1b | 2009-04-28 20:17:49 +0100 | [diff] [blame] | 478 | *prevp = f->release_next; |
Marcin Slusarz | 8b8f79b | 2010-06-13 23:56:54 +0200 | [diff] [blame^] | 479 | f->release_next = NULL; |
| 480 | f->scheduled_for_release = false; |
Stuart Bennett | d0fc63f | 2009-03-08 20:21:35 +0200 | [diff] [blame] | 481 | } |
Marcin Slusarz | 8b8f79b | 2010-06-13 23:56:54 +0200 | [diff] [blame^] | 482 | f = *prevp; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 483 | } |
| 484 | spin_unlock_irqrestore(&kmmio_lock, flags); |
Stuart Bennett | d0fc63f | 2009-03-08 20:21:35 +0200 | [diff] [blame] | 485 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 486 | /* This is the real RCU destroy call. */ |
| 487 | call_rcu(&dr->rcu, rcu_free_kmmio_fault_pages); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 488 | } |
| 489 | |
| 490 | /* |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 491 | * 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] | 492 | * sure that the callbacks will not be called anymore. Only after that |
| 493 | * you may actually release your struct kmmio_probe. |
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 | * Unregistering a kmmio fault page has three steps: |
| 496 | * 1. release_kmmio_fault_page() |
| 497 | * Disarm the page, wait a grace period to let all faults finish. |
| 498 | * 2. remove_kmmio_fault_pages() |
| 499 | * Remove the pages from kmmio_page_table. |
| 500 | * 3. rcu_free_kmmio_fault_pages() |
Shaun Patterson | 8055039 | 2009-12-05 10:41:34 -0500 | [diff] [blame] | 501 | * Actually free the kmmio_fault_page structs as with RCU. |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 502 | */ |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 503 | void unregister_kmmio_probe(struct kmmio_probe *p) |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 504 | { |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 505 | unsigned long flags; |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 506 | unsigned long size = 0; |
Pekka Paalanen | 87e547f | 2008-05-12 21:21:03 +0200 | [diff] [blame] | 507 | const unsigned long size_lim = p->len + (p->addr & ~PAGE_MASK); |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 508 | struct kmmio_fault_page *release_list = NULL; |
| 509 | struct kmmio_delayed_release *drelease; |
| 510 | |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 511 | spin_lock_irqsave(&kmmio_lock, flags); |
Pekka Paalanen | 87e547f | 2008-05-12 21:21:03 +0200 | [diff] [blame] | 512 | while (size < size_lim) { |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 513 | release_kmmio_fault_page(p->addr + size, &release_list); |
| 514 | size += PAGE_SIZE; |
| 515 | } |
| 516 | list_del_rcu(&p->list); |
| 517 | kmmio_count--; |
Pekka Paalanen | d61fc44 | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 518 | spin_unlock_irqrestore(&kmmio_lock, flags); |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 519 | |
Marcin Slusarz | 8b8f79b | 2010-06-13 23:56:54 +0200 | [diff] [blame^] | 520 | if (!release_list) |
| 521 | return; |
| 522 | |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 523 | drelease = kmalloc(sizeof(*drelease), GFP_ATOMIC); |
| 524 | if (!drelease) { |
Joe Perches | 1bd591a | 2009-12-09 10:45:36 -0800 | [diff] [blame] | 525 | pr_crit("leaking kmmio_fault_page objects.\n"); |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 526 | return; |
| 527 | } |
| 528 | drelease->release_list = release_list; |
| 529 | |
| 530 | /* |
| 531 | * This is not really RCU here. We have just disarmed a set of |
| 532 | * pages so that they cannot trigger page faults anymore. However, |
| 533 | * we cannot remove the pages from kmmio_page_table, |
| 534 | * because a probe hit might be in flight on another CPU. The |
| 535 | * pages are collected into a list, and they will be removed from |
| 536 | * kmmio_page_table when it is certain that no probe hit related to |
| 537 | * these pages can be in flight. RCU grace period sounds like a |
| 538 | * good choice. |
| 539 | * |
| 540 | * If we removed the pages too early, kmmio page fault handler might |
| 541 | * not find the respective kmmio_fault_page and determine it's not |
| 542 | * a kmmio fault, when it actually is. This would lead to madness. |
| 543 | */ |
| 544 | call_rcu(&drelease->rcu, remove_kmmio_fault_pages); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 545 | } |
Pekka Paalanen | 0fd0e3d | 2008-05-12 21:20:57 +0200 | [diff] [blame] | 546 | EXPORT_SYMBOL(unregister_kmmio_probe); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 547 | |
Stuart Bennett | 0f9a623 | 2009-04-28 20:17:51 +0100 | [diff] [blame] | 548 | static int |
| 549 | kmmio_die_notifier(struct notifier_block *nb, unsigned long val, void *args) |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 550 | { |
| 551 | struct die_args *arg = args; |
Luca Barbieri | 0bb7a95 | 2010-01-16 10:39:30 +0100 | [diff] [blame] | 552 | unsigned long* dr6_p = (unsigned long *)ERR_PTR(arg->err); |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 553 | |
Luca Barbieri | 0bb7a95 | 2010-01-16 10:39:30 +0100 | [diff] [blame] | 554 | if (val == DIE_DEBUG && (*dr6_p & DR_STEP)) |
| 555 | if (post_kmmio_handler(*dr6_p, arg->regs) == 1) { |
K.Prasad | 62edab9 | 2009-06-01 23:47:06 +0530 | [diff] [blame] | 556 | /* |
| 557 | * Reset the BS bit in dr6 (pointed by args->err) to |
| 558 | * denote completion of processing |
| 559 | */ |
Luca Barbieri | 0bb7a95 | 2010-01-16 10:39:30 +0100 | [diff] [blame] | 560 | *dr6_p &= ~DR_STEP; |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 561 | return NOTIFY_STOP; |
K.Prasad | 62edab9 | 2009-06-01 23:47:06 +0530 | [diff] [blame] | 562 | } |
Pekka Paalanen | 8b7d89d | 2008-05-12 21:20:56 +0200 | [diff] [blame] | 563 | |
| 564 | return NOTIFY_DONE; |
| 565 | } |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 566 | |
| 567 | static struct notifier_block nb_die = { |
| 568 | .notifier_call = kmmio_die_notifier |
| 569 | }; |
| 570 | |
Stuart Bennett | 0f9a623 | 2009-04-28 20:17:51 +0100 | [diff] [blame] | 571 | int kmmio_init(void) |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 572 | { |
| 573 | int i; |
Stuart Bennett | 0f9a623 | 2009-04-28 20:17:51 +0100 | [diff] [blame] | 574 | |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 575 | for (i = 0; i < KMMIO_PAGE_TABLE_SIZE; i++) |
| 576 | INIT_LIST_HEAD(&kmmio_page_table[i]); |
Stuart Bennett | 0f9a623 | 2009-04-28 20:17:51 +0100 | [diff] [blame] | 577 | |
Pekka Paalanen | 1382953 | 2008-05-12 21:20:58 +0200 | [diff] [blame] | 578 | return register_die_notifier(&nb_die); |
| 579 | } |
Stuart Bennett | 0f9a623 | 2009-04-28 20:17:51 +0100 | [diff] [blame] | 580 | |
| 581 | void kmmio_cleanup(void) |
| 582 | { |
| 583 | int i; |
| 584 | |
| 585 | unregister_die_notifier(&nb_die); |
| 586 | for (i = 0; i < KMMIO_PAGE_TABLE_SIZE; i++) { |
| 587 | WARN_ONCE(!list_empty(&kmmio_page_table[i]), |
| 588 | KERN_ERR "kmmio_page_table not empty at cleanup, any further tracing will leak memory.\n"); |
| 589 | } |
| 590 | } |