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

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* 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: Stuart Bennett <stuart@freedesktop.org>
Acked-by: Pekka Paalanen <pq@iki.fi>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1240946271-7083-4-git-send-email-stuart@freedesktop.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Stuart Bennett 2009-04-28 20:17:50 +01:00 committed by Ingo Molnar
parent 0492e1bb8f
commit 46e91d00b1
1 changed files with 22 additions and 21 deletions
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43
arch/x86/mm/kmmio.c
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@ -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);
v &= ~_PAGE_PRESENT;
if (present)
v |= _PAGE_PRESENT;
if (clear) {
*old = v & _PAGE_PRESENT;
v &= ~_PAGE_PRESENT;
} else /* presume this has been called with clear==true previously */
v |= *old;
set_pmd(pmd, __pmd(v));
}
static void 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);
v &= ~_PAGE_PRESENT;
if (present)
v |= _PAGE_PRESENT;
if (clear) {
*old = v & _PAGE_PRESENT;
v &= ~_PAGE_PRESENT;
} else /* presume this has been called with clear==true previously */
v |= *old;
set_pte_atomic(pte, __pte(v));
}
static int 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;