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authorGerald Schaefer <gerald.schaefer@de.ibm.com>2019-02-03 21:36:46 +0100
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2019-04-29 10:47:10 +0200
commitfd3d2742d558d33560ec5dfee3001e561b5c0822 (patch)
tree0dfeef81cd3d167e4377a5948297d704f7f4f7b1 /arch/s390
parentff4a742dde3c4b80a91cdd754fed3bc576df28c9 (diff)
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>
Diffstat (limited to 'arch/s390')
-rw-r--r--arch/s390/kernel/kprobes.c35
1 files changed, 18 insertions, 17 deletions
diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
index 7c0a095e9c5f..263426dcf97d 100644
--- a/arch/s390/kernel/kprobes.c
+++ b/arch/s390/kernel/kprobes.c
@@ -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;