Commit e9d54cae authored by Stuart Bennett's avatar Stuart Bennett Committed by Ingo Molnar
Browse files

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: default avatarStuart Bennett <stuart@freedesktop.org>
Signed-off-by: default avatarPekka Paalanen <pq@iki.fi>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 5ff93697

arch/x86/mm/kmmio.c

+17 −8
Original line number Diff line number Diff line
@@ -105,7 +105,7 @@ static struct kmmio_fault_page *get_kmmio_fault_page(unsigned long page) 
	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 @@ static void set_page_present(unsigned long addr, bool present, 


	if (!pte) {

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

		return;

		return -1;

	}



	if (pglevel)
@@ -140,22 +140,27 @@ static void set_page_present(unsigned long addr, bool present, 


	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 @@ static int add_kmmio_fault_page(unsigned long page) 


	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;

}

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