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Commit 46e91d00 authored by Stuart Bennett's avatar Stuart Bennett Committed by Ingo Molnar
Browse files

tracing: x86, mmiotrace: refactor clearing/restore of page presence 



* change function names to clear_* from set_*: in reality we only clear
  and restore page presence, and never unconditionally set present.
  Using clear_*({true, false}, ...) is therefore more honest than
  set_*({false, true}, ...)

* upgrade presence storage to pteval_t: doing user-space tracing will
  require saving and manipulation of the _PAGE_PROTNONE bit, in addition
  to the existing _PAGE_PRESENT changes, and having multiple bools stored
  and passed around does not seem optimal

[ Impact: refactor, clean up mmiotrace code ]

Signed-off-by: default avatarStuart Bennett <stuart@freedesktop.org>
Acked-by: default avatarPekka Paalanen <pq@iki.fi>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1240946271-7083-4-git-send-email-stuart@freedesktop.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 0492e1bb

arch/x86/mm/kmmio.c

+22 −21
Original line number Diff line number Diff line
@@ -32,7 +32,7 @@ struct kmmio_fault_page { 
	struct list_head list;

	struct kmmio_fault_page *release_next;

	unsigned long page; /* location of the fault page */

	bool old_presence; /* page presence prior to arming */

	pteval_t old_presence; /* page presence prior to arming */

	bool armed;



	/*
@@ -108,49 +108,51 @@ static struct kmmio_fault_page *get_kmmio_fault_page(unsigned long page) 
	return NULL;

}



static void set_pmd_presence(pmd_t *pmd, bool present, bool *old)

static void clear_pmd_presence(pmd_t *pmd, bool clear, pmdval_t *old)

{

	pmdval_t v = pmd_val(*pmd);

	*old = !!(v & _PAGE_PRESENT);

	if (clear) {

		*old = v & _PAGE_PRESENT;

		v &= ~_PAGE_PRESENT;

	if (present)

		v |= _PAGE_PRESENT;

	} else	/* presume this has been called with clear==true previously */

		v |= *old;

	set_pmd(pmd, __pmd(v));

}



static void set_pte_presence(pte_t *pte, bool present, bool *old)

static void clear_pte_presence(pte_t *pte, bool clear, pteval_t *old)

{

	pteval_t v = pte_val(*pte);

	*old = !!(v & _PAGE_PRESENT);

	if (clear) {

		*old = v & _PAGE_PRESENT;

		v &= ~_PAGE_PRESENT;

	if (present)

		v |= _PAGE_PRESENT;

	} else	/* presume this has been called with clear==true previously */

		v |= *old;

	set_pte_atomic(pte, __pte(v));

}



static int set_page_presence(unsigned long addr, bool present, bool *old)

static int clear_page_presence(struct kmmio_fault_page *f, bool clear)

{

	unsigned int level;

	pte_t *pte = lookup_address(addr, &level);

	pte_t *pte = lookup_address(f->page, &level);



	if (!pte) {

		pr_err("kmmio: no pte for page 0x%08lx\n", addr);

		pr_err("kmmio: no pte for page 0x%08lx\n", f->page);

		return -1;

	}



	switch (level) {

	case PG_LEVEL_2M:

		set_pmd_presence((pmd_t *)pte, present, old);

		clear_pmd_presence((pmd_t *)pte, clear, &f->old_presence);

		break;

	case PG_LEVEL_4K:

		set_pte_presence(pte, present, old);

		clear_pte_presence(pte, clear, &f->old_presence);

		break;

	default:

		pr_err("kmmio: unexpected page level 0x%x.\n", level);

		return -1;

	}



	__flush_tlb_one(addr);

	__flush_tlb_one(f->page);

	return 0;

}
@@ -171,9 +173,9 @@ static int arm_kmmio_fault_page(struct kmmio_fault_page *f) 
	WARN_ONCE(f->armed, KERN_ERR "kmmio page already armed.\n");

	if (f->armed) {

		pr_warning("kmmio double-arm: page 0x%08lx, ref %d, old %d\n",

					f->page, f->count, f->old_presence);

					f->page, f->count, !!f->old_presence);

	}

	ret = set_page_presence(f->page, false, &f->old_presence);

	ret = clear_page_presence(f, true);

	WARN_ONCE(ret < 0, KERN_ERR "kmmio arming 0x%08lx failed.\n", f->page);

	f->armed = true;

	return ret;
@@ -182,8 +184,7 @@ static int arm_kmmio_fault_page(struct kmmio_fault_page *f) 
/** Restore the given page to saved presence state. */

static void disarm_kmmio_fault_page(struct kmmio_fault_page *f)

{

	bool tmp;

	int ret = set_page_presence(f->page, f->old_presence, &tmp);

	int ret = clear_page_presence(f, false);

	WARN_ONCE(ret < 0,

			KERN_ERR "kmmio disarming 0x%08lx failed.\n", f->page);

	f->armed = false;