x86 mmiotrace: WARN_ONCE if dis/arming a page fails
Print a full warning once, if arming or disarming a page fails.
Also, if initial arming fails, do not handle the page further. This
avoids the possibility of a page failing to arm and then later claiming
to have handled any fault on that page.
WARN_ONCE added by Pekka Paalanen.
Signed-off-by: Stuart Bennett <stuart@freedesktop.org>
Signed-off-by: Pekka Paalanen <pq@iki.fi>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/mm/kmmio.c b/arch/x86/mm/kmmio.c
index 93d8203..fb1f115 100644
--- a/arch/x86/mm/kmmio.c
+++ b/arch/x86/mm/kmmio.c
@@ -105,7 +105,7 @@
return NULL;
}
-static void set_page_present(unsigned long addr, bool present,
+static int set_page_present(unsigned long addr, bool present,
unsigned int *pglevel)
{
pteval_t pteval;
@@ -116,7 +116,7 @@
if (!pte) {
pr_err("kmmio: no pte for page 0x%08lx\n", addr);
- return;
+ return -1;
}
if (pglevel)
@@ -140,22 +140,27 @@
default:
pr_err("kmmio: unexpected page level 0x%x.\n", level);
- return;
+ return -1;
}
__flush_tlb_one(addr);
+
+ return 0;
}
/** Mark the given page as not present. Access to it will trigger a fault. */
-static void arm_kmmio_fault_page(unsigned long page, unsigned int *pglevel)
+static int arm_kmmio_fault_page(unsigned long page, unsigned int *pglevel)
{
- set_page_present(page & PAGE_MASK, false, pglevel);
+ int ret = set_page_present(page & PAGE_MASK, false, pglevel);
+ WARN_ONCE(ret < 0, KERN_ERR "kmmio arming 0x%08lx failed.\n", page);
+ return ret;
}
/** Mark the given page as present. */
static void disarm_kmmio_fault_page(unsigned long page, unsigned int *pglevel)
{
- set_page_present(page & PAGE_MASK, true, pglevel);
+ int ret = set_page_present(page & PAGE_MASK, true, pglevel);
+ WARN_ONCE(ret < 0, KERN_ERR "kmmio disarming 0x%08lx failed.\n", page);
}
/*
@@ -326,9 +331,13 @@
f->count = 1;
f->page = page;
- list_add_rcu(&f->list, kmmio_page_list(f->page));
- arm_kmmio_fault_page(f->page, NULL);
+ if (arm_kmmio_fault_page(f->page, NULL)) {
+ kfree(f);
+ return -1;
+ }
+
+ list_add_rcu(&f->list, kmmio_page_list(f->page));
return 0;
}