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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: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Gerald Schaefer 2019-02-03 21:36:46 +01:00 committed by Martin Schwidefsky
parent ff4a742dde
commit fd3d2742d5
1 changed files with 18 additions and 17 deletions
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35
arch/s390/kernel/kprobes.c
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@ -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)
static int insn_page_in_use;
static char insn_page[PAGE_SIZE] __aligned(PAGE_SIZE);
static void *alloc_s390_insn_page(void)
{
void *page;
page = (void *) __get_free_page(GFP_KERNEL | GFP_DMA);
if (page)
set_memory_x((unsigned long) page, 1);
return page;
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;