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Commit fd3d2742 authored by Gerald Schaefer's avatar Gerald Schaefer Committed by Martin Schwidefsky
Browse files

s390/kprobes: use static buffer for insn_page 



With a relocatable kernel that could reside at any place in memory, the
current logic for allocating a kprobes insn_page does not work. The
GFP_DMA allocated buffer might be more than 2 GB away from the kernel.

Use a static buffer for the insn_page instead.

Signed-off-by: default avatarGerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: default avatarPhilipp Rudo <prudo@linux.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent ff4a742d

arch/s390/kernel/kprobes.c

+18 −17
Original line number Diff line number Diff line
@@ -27,29 +27,30 @@ DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); 


struct kretprobe_blackpoint kretprobe_blacklist[] = { };



DEFINE_INSN_CACHE_OPS(dmainsn);

DEFINE_INSN_CACHE_OPS(s390_insn);



static void *alloc_dmainsn_page(void)

{

	void *page;

static int insn_page_in_use;

static char insn_page[PAGE_SIZE] __aligned(PAGE_SIZE);



	page = (void *) __get_free_page(GFP_KERNEL | GFP_DMA);

	if (page)

		set_memory_x((unsigned long) page, 1);

	return page;

static void *alloc_s390_insn_page(void)

{

	if (xchg(&insn_page_in_use, 1) == 1)

		return NULL;

	set_memory_x((unsigned long) &insn_page, 1);

	return &insn_page;

}



static void free_dmainsn_page(void *page)

static void free_s390_insn_page(void *page)

{

	set_memory_nx((unsigned long) page, 1);

	free_page((unsigned long)page);

	xchg(&insn_page_in_use, 0);

}



struct kprobe_insn_cache kprobe_dmainsn_slots = {

	.mutex = __MUTEX_INITIALIZER(kprobe_dmainsn_slots.mutex),

	.alloc = alloc_dmainsn_page,

	.free = free_dmainsn_page,

	.pages = LIST_HEAD_INIT(kprobe_dmainsn_slots.pages),

struct kprobe_insn_cache kprobe_s390_insn_slots = {

	.mutex = __MUTEX_INITIALIZER(kprobe_s390_insn_slots.mutex),

	.alloc = alloc_s390_insn_page,

	.free = free_s390_insn_page,

	.pages = LIST_HEAD_INIT(kprobe_s390_insn_slots.pages),

	.insn_size = MAX_INSN_SIZE,

};
@@ -102,7 +103,7 @@ static int s390_get_insn_slot(struct kprobe *p) 
	 */

	p->ainsn.insn = NULL;

	if (is_kernel_addr(p->addr))

		p->ainsn.insn = get_dmainsn_slot();

		p->ainsn.insn = get_s390_insn_slot();

	else if (is_module_addr(p->addr))

		p->ainsn.insn = get_insn_slot();

	return p->ainsn.insn ? 0 : -ENOMEM;
@@ -114,7 +115,7 @@ static void s390_free_insn_slot(struct kprobe *p) 
	if (!p->ainsn.insn)

		return;

	if (is_kernel_addr(p->addr))

		free_dmainsn_slot(p->ainsn.insn, 0);

		free_s390_insn_slot(p->ainsn.insn, 0);

	else

		free_insn_slot(p->ainsn.insn, 0);

	p->ainsn.insn = NULL;