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Merge branch 'tracing/mmiotrace' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'tracing/mmiotrace' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86 mmiotrace: fix race with release_kmmio_fault_page() x86 mmiotrace: improve handling of secondary faults x86 mmiotrace: split set_page_presence() x86 mmiotrace: fix save/restore page table state x86 mmiotrace: WARN_ONCE if dis/arming a page fails x86: add far read test to testmmiotrace x86: count errors in testmmiotrace.ko
This commit is contained in:
Linus Torvalds
commit
f2a4165526
@ -32,11 +32,14 @@ struct kmmio_fault_page {
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struct list_head list;
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struct kmmio_fault_page *release_next;
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unsigned long page; /* location of the fault page */
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bool old_presence; /* page presence prior to arming */
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bool armed;
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/*
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* Number of times this page has been registered as a part
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* of a probe. If zero, page is disarmed and this may be freed.
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* Used only by writers (RCU).
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* Used only by writers (RCU) and post_kmmio_handler().
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* Protected by kmmio_lock, when linked into kmmio_page_table.
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*/
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int count;
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};
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@ -105,57 +108,85 @@ static struct kmmio_fault_page *get_kmmio_fault_page(unsigned long page)
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return NULL;
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}
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static void set_page_present(unsigned long addr, bool present,
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unsigned int *pglevel)
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static void set_pmd_presence(pmd_t *pmd, bool present, bool *old)
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{
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pmdval_t v = pmd_val(*pmd);
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*old = !!(v & _PAGE_PRESENT);
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v &= ~_PAGE_PRESENT;
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if (present)
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v |= _PAGE_PRESENT;
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set_pmd(pmd, __pmd(v));
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}
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static void set_pte_presence(pte_t *pte, bool present, bool *old)
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{
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pteval_t v = pte_val(*pte);
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*old = !!(v & _PAGE_PRESENT);
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v &= ~_PAGE_PRESENT;
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if (present)
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v |= _PAGE_PRESENT;
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set_pte_atomic(pte, __pte(v));
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}
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static int set_page_presence(unsigned long addr, bool present, bool *old)
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{
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pteval_t pteval;
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pmdval_t pmdval;
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unsigned int level;
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pmd_t *pmd;
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pte_t *pte = lookup_address(addr, &level);
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if (!pte) {
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pr_err("kmmio: no pte for page 0x%08lx\n", addr);
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return;
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return -1;
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}
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if (pglevel)
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*pglevel = level;
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switch (level) {
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case PG_LEVEL_2M:
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pmd = (pmd_t *)pte;
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pmdval = pmd_val(*pmd) & ~_PAGE_PRESENT;
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if (present)
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pmdval |= _PAGE_PRESENT;
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set_pmd(pmd, __pmd(pmdval));
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set_pmd_presence((pmd_t *)pte, present, old);
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break;
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case PG_LEVEL_4K:
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pteval = pte_val(*pte) & ~_PAGE_PRESENT;
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if (present)
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pteval |= _PAGE_PRESENT;
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set_pte_atomic(pte, __pte(pteval));
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set_pte_presence(pte, present, old);
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break;
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default:
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pr_err("kmmio: unexpected page level 0x%x.\n", level);
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return;
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return -1;
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}
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__flush_tlb_one(addr);
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return 0;
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}
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/** Mark the given page as not present. Access to it will trigger a fault. */
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static void arm_kmmio_fault_page(unsigned long page, unsigned int *pglevel)
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/*
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* Mark the given page as not present. Access to it will trigger a fault.
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*
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* Struct kmmio_fault_page is protected by RCU and kmmio_lock, but the
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* protection is ignored here. RCU read lock is assumed held, so the struct
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* will not disappear unexpectedly. Furthermore, the caller must guarantee,
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* that double arming the same virtual address (page) cannot occur.
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*
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* Double disarming on the other hand is allowed, and may occur when a fault
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* and mmiotrace shutdown happen simultaneously.
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*/
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static int arm_kmmio_fault_page(struct kmmio_fault_page *f)
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{
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set_page_present(page & PAGE_MASK, false, pglevel);
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int ret;
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WARN_ONCE(f->armed, KERN_ERR "kmmio page already armed.\n");
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if (f->armed) {
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pr_warning("kmmio double-arm: page 0x%08lx, ref %d, old %d\n",
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f->page, f->count, f->old_presence);
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}
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ret = set_page_presence(f->page, false, &f->old_presence);
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WARN_ONCE(ret < 0, KERN_ERR "kmmio arming 0x%08lx failed.\n", f->page);
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f->armed = true;
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return ret;
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}
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/** Mark the given page as present. */
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static void disarm_kmmio_fault_page(unsigned long page, unsigned int *pglevel)
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/** Restore the given page to saved presence state. */
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static void disarm_kmmio_fault_page(struct kmmio_fault_page *f)
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{
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set_page_present(page & PAGE_MASK, true, pglevel);
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bool tmp;
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int ret = set_page_presence(f->page, f->old_presence, &tmp);
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WARN_ONCE(ret < 0,
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KERN_ERR "kmmio disarming 0x%08lx failed.\n", f->page);
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f->armed = false;
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}
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/*
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@ -202,28 +233,32 @@ int kmmio_handler(struct pt_regs *regs, unsigned long addr)
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ctx = &get_cpu_var(kmmio_ctx);
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if (ctx->active) {
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disarm_kmmio_fault_page(faultpage->page, NULL);
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if (addr == ctx->addr) {
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/*
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* On SMP we sometimes get recursive probe hits on the
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* same address. Context is already saved, fall out.
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* A second fault on the same page means some other
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* condition needs handling by do_page_fault(), the
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* page really not being present is the most common.
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*/
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pr_debug("kmmio: duplicate probe hit on CPU %d, for "
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"address 0x%08lx.\n",
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smp_processor_id(), addr);
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ret = 1;
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goto no_kmmio_ctx;
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}
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/*
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* Prevent overwriting already in-flight context.
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* This should not happen, let's hope disarming at least
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* prevents a panic.
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*/
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pr_emerg("kmmio: recursive probe hit on CPU %d, "
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pr_debug("kmmio: secondary hit for 0x%08lx CPU %d.\n",
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addr, smp_processor_id());
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if (!faultpage->old_presence)
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pr_info("kmmio: unexpected secondary hit for "
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"address 0x%08lx on CPU %d.\n", addr,
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smp_processor_id());
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} else {
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/*
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* Prevent overwriting already in-flight context.
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* This should not happen, let's hope disarming at
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* least prevents a panic.
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*/
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pr_emerg("kmmio: recursive probe hit on CPU %d, "
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"for address 0x%08lx. Ignoring.\n",
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smp_processor_id(), addr);
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pr_emerg("kmmio: previous hit was at 0x%08lx.\n",
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ctx->addr);
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pr_emerg("kmmio: previous hit was at 0x%08lx.\n",
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ctx->addr);
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disarm_kmmio_fault_page(faultpage);
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}
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goto no_kmmio_ctx;
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}
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ctx->active++;
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@ -244,7 +279,7 @@ int kmmio_handler(struct pt_regs *regs, unsigned long addr)
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regs->flags &= ~X86_EFLAGS_IF;
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/* Now we set present bit in PTE and single step. */
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disarm_kmmio_fault_page(ctx->fpage->page, NULL);
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disarm_kmmio_fault_page(ctx->fpage);
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/*
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* If another cpu accesses the same page while we are stepping,
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@ -275,7 +310,7 @@ static int post_kmmio_handler(unsigned long condition, struct pt_regs *regs)
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struct kmmio_context *ctx = &get_cpu_var(kmmio_ctx);
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if (!ctx->active) {
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pr_debug("kmmio: spurious debug trap on CPU %d.\n",
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pr_warning("kmmio: spurious debug trap on CPU %d.\n",
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smp_processor_id());
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goto out;
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}
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@ -283,7 +318,11 @@ static int post_kmmio_handler(unsigned long condition, struct pt_regs *regs)
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if (ctx->probe && ctx->probe->post_handler)
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ctx->probe->post_handler(ctx->probe, condition, regs);
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arm_kmmio_fault_page(ctx->fpage->page, NULL);
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/* Prevent racing against release_kmmio_fault_page(). */
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spin_lock(&kmmio_lock);
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if (ctx->fpage->count)
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arm_kmmio_fault_page(ctx->fpage);
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spin_unlock(&kmmio_lock);
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regs->flags &= ~X86_EFLAGS_TF;
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regs->flags |= ctx->saved_flags;
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@ -315,20 +354,24 @@ static int add_kmmio_fault_page(unsigned long page)
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f = get_kmmio_fault_page(page);
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if (f) {
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if (!f->count)
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arm_kmmio_fault_page(f->page, NULL);
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arm_kmmio_fault_page(f);
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f->count++;
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return 0;
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}
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f = kmalloc(sizeof(*f), GFP_ATOMIC);
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f = kzalloc(sizeof(*f), GFP_ATOMIC);
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if (!f)
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return -1;
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f->count = 1;
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f->page = page;
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list_add_rcu(&f->list, kmmio_page_list(f->page));
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arm_kmmio_fault_page(f->page, NULL);
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if (arm_kmmio_fault_page(f)) {
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kfree(f);
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return -1;
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}
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list_add_rcu(&f->list, kmmio_page_list(f->page));
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return 0;
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}
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@ -347,7 +390,7 @@ static void release_kmmio_fault_page(unsigned long page,
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f->count--;
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BUG_ON(f->count < 0);
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if (!f->count) {
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disarm_kmmio_fault_page(f->page, NULL);
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disarm_kmmio_fault_page(f);
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f->release_next = *release_list;
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*release_list = f;
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}
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@ -1,5 +1,5 @@
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/*
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* Written by Pekka Paalanen, 2008 <pq@iki.fi>
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* Written by Pekka Paalanen, 2008-2009 <pq@iki.fi>
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*/
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#include <linux/module.h>
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#include <linux/io.h>
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@ -9,35 +9,74 @@
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static unsigned long mmio_address;
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module_param(mmio_address, ulong, 0);
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MODULE_PARM_DESC(mmio_address, "Start address of the mapping of 16 kB.");
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MODULE_PARM_DESC(mmio_address, " Start address of the mapping of 16 kB "
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"(or 8 MB if read_far is non-zero).");
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static unsigned long read_far = 0x400100;
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module_param(read_far, ulong, 0);
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MODULE_PARM_DESC(read_far, " Offset of a 32-bit read within 8 MB "
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"(default: 0x400100).");
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static unsigned v16(unsigned i)
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{
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return i * 12 + 7;
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}
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static unsigned v32(unsigned i)
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{
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return i * 212371 + 13;
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}
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static void do_write_test(void __iomem *p)
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{
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unsigned int i;
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pr_info(MODULE_NAME ": write test.\n");
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mmiotrace_printk("Write test.\n");
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for (i = 0; i < 256; i++)
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iowrite8(i, p + i);
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for (i = 1024; i < (5 * 1024); i += 2)
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iowrite16(i * 12 + 7, p + i);
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iowrite16(v16(i), p + i);
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for (i = (5 * 1024); i < (16 * 1024); i += 4)
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iowrite32(i * 212371 + 13, p + i);
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iowrite32(v32(i), p + i);
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}
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static void do_read_test(void __iomem *p)
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{
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unsigned int i;
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unsigned errs[3] = { 0 };
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pr_info(MODULE_NAME ": read test.\n");
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mmiotrace_printk("Read test.\n");
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for (i = 0; i < 256; i++)
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ioread8(p + i);
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if (ioread8(p + i) != i)
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++errs[0];
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for (i = 1024; i < (5 * 1024); i += 2)
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ioread16(p + i);
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if (ioread16(p + i) != v16(i))
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++errs[1];
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for (i = (5 * 1024); i < (16 * 1024); i += 4)
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ioread32(p + i);
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if (ioread32(p + i) != v32(i))
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++errs[2];
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mmiotrace_printk("Read errors: 8-bit %d, 16-bit %d, 32-bit %d.\n",
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errs[0], errs[1], errs[2]);
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}
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static void do_test(void)
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static void do_read_far_test(void __iomem *p)
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{
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void __iomem *p = ioremap_nocache(mmio_address, 0x4000);
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pr_info(MODULE_NAME ": read far test.\n");
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mmiotrace_printk("Read far test.\n");
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ioread32(p + read_far);
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}
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static void do_test(unsigned long size)
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{
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void __iomem *p = ioremap_nocache(mmio_address, size);
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if (!p) {
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pr_err(MODULE_NAME ": could not ioremap, aborting.\n");
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return;
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@ -45,11 +84,15 @@ static void do_test(void)
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mmiotrace_printk("ioremap returned %p.\n", p);
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do_write_test(p);
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do_read_test(p);
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if (read_far && read_far < size - 4)
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do_read_far_test(p);
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iounmap(p);
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}
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static int __init init(void)
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{
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unsigned long size = (read_far) ? (8 << 20) : (16 << 10);
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if (mmio_address == 0) {
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pr_err(MODULE_NAME ": you have to use the module argument "
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"mmio_address.\n");
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@ -58,10 +101,11 @@ static int __init init(void)
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return -ENXIO;
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}
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pr_warning(MODULE_NAME ": WARNING: mapping 16 kB @ 0x%08lx "
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"in PCI address space, and writing "
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"rubbish in there.\n", mmio_address);
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do_test();
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pr_warning(MODULE_NAME ": WARNING: mapping %lu kB @ 0x%08lx in PCI "
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"address space, and writing 16 kB of rubbish in there.\n",
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size >> 10, mmio_address);
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do_test(size);
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pr_info(MODULE_NAME ": All done.\n");
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return 0;
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}
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