summaryrefslogtreecommitdiffstats
path: root/arch/s390/kernel/kprobes.c
diff options
context:
space:
mode:
authorHeiko Carstens <hca@linux.ibm.com>2020-09-18 10:26:19 +0200
committerVasily Gorbik <gor@linux.ibm.com>2020-10-09 23:45:30 +0200
commitb61e1f3281c5a53f24f47849873463514f58c1b8 (patch)
tree73623ca152797153f08cddc9bca78cb8f619869f /arch/s390/kernel/kprobes.c
parenteefc69a09ca5b441ee136f9fb68ab5970cfc2d51 (diff)
downloadlinux-b61e1f3281c5a53f24f47849873463514f58c1b8.tar.bz2
s390/kprobes: move insn_page to text segment
Move the in-kernel kprobes insn page to text segment. Rationale: having that page in rw data segment is suboptimal, since as soon as a kprobe is set, this will split the 1:1 kernel mapping for a single page which get new permissions. Note: there is always at least one kprobe present for the kretprobe trampoline; so the mapping will always be split into smaller 4k mappings because of this. Moving the kprobes insn page into text segment makes sure that the page is mapped RO/X in any case, and avoids that the 1:1 mapping is split. The kprobe insn_page is defined as a dummy function which is filled with "br %r14" instructions. Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390/kernel/kprobes.c')
-rw-r--r--arch/s390/kernel/kprobes.c6
1 files changed, 2 insertions, 4 deletions
diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
index b34fa4eef742..6574774d404e 100644
--- a/arch/s390/kernel/kprobes.c
+++ b/arch/s390/kernel/kprobes.c
@@ -22,6 +22,7 @@
#include <asm/set_memory.h>
#include <asm/sections.h>
#include <asm/dis.h>
+#include "entry.h"
DEFINE_PER_CPU(struct kprobe *, current_kprobe);
DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
@@ -31,7 +32,6 @@ struct kretprobe_blackpoint kretprobe_blacklist[] = { };
DEFINE_INSN_CACHE_OPS(s390_insn);
static int insn_page_in_use;
-static char insn_page[PAGE_SIZE] __aligned(PAGE_SIZE);
void *alloc_insn_page(void)
{
@@ -53,13 +53,11 @@ static void *alloc_s390_insn_page(void)
{
if (xchg(&insn_page_in_use, 1) == 1)
return NULL;
- __set_memory((unsigned long) &insn_page, 1, SET_MEMORY_RO | SET_MEMORY_X);
- return &insn_page;
+ return &kprobes_insn_page;
}
static void free_s390_insn_page(void *page)
{
- __set_memory((unsigned long) page, 1, SET_MEMORY_RW | SET_MEMORY_NX);
xchg(&insn_page_in_use, 0);
}