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authorSven Schnelle <svens@linux.ibm.com>2022-01-23 20:20:09 +0100
committerVasily Gorbik <gor@linux.ibm.com>2022-02-06 23:31:29 +0100
commit98c0d24d1e7576a853b0812d95e599ba1a909e21 (patch)
tree5a74a240467e3e89ecba483f2b0cff5c813ac29e /arch/s390/kernel/ftrace.c
parents390: remove invalid email address of Heiko Carstens (diff)
downloadlinux-98c0d24d1e7576a853b0812d95e599ba1a909e21.tar.xz
linux-98c0d24d1e7576a853b0812d95e599ba1a909e21.zip
s390/ftrace: verify opcode before applying patch
commit 72b3942a173c ("scripts: ftrace - move the sort-processing in ftrace_init") had the unexpected side effect that wrong code locations were patched. To prevent this from happening again, verify the opcode before patching it. Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Reviewed-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390/kernel/ftrace.c')
-rw-r--r--arch/s390/kernel/ftrace.c43
1 files changed, 27 insertions, 16 deletions
diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c
index 61f72c7fb0da..1db9cc795034 100644
--- a/arch/s390/kernel/ftrace.c
+++ b/arch/s390/kernel/ftrace.c
@@ -164,31 +164,32 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
return 0;
}
-static void brcl_disable(void *brcl)
+static int ftrace_patch_branch_mask(void *addr, u16 expected, bool enable)
{
- u8 op = 0x04; /* set mask field to zero */
+ u16 old;
+ u8 op;
- s390_kernel_write((char *)brcl + 1, &op, sizeof(op));
+ if (get_kernel_nofault(old, addr))
+ return -EFAULT;
+ if (old != expected)
+ return -EINVAL;
+ /* set mask field to all ones or zeroes */
+ op = enable ? 0xf4 : 0x04;
+ s390_kernel_write((char *)addr + 1, &op, sizeof(op));
+ return 0;
}
int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
unsigned long addr)
{
- brcl_disable((void *)rec->ip);
- return 0;
-}
-
-static void brcl_enable(void *brcl)
-{
- u8 op = 0xf4; /* set mask field to all ones */
-
- s390_kernel_write((char *)brcl + 1, &op, sizeof(op));
+ /* Expect brcl 0xf,... */
+ return ftrace_patch_branch_mask((void *)rec->ip, 0xc0f4, false);
}
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
- brcl_enable((void *)rec->ip);
- return 0;
+ /* Expect brcl 0x0,... */
+ return ftrace_patch_branch_mask((void *)rec->ip, 0xc004, true);
}
int ftrace_update_ftrace_func(ftrace_func_t func)
@@ -261,14 +262,24 @@ NOKPROBE_SYMBOL(prepare_ftrace_return);
*/
int ftrace_enable_ftrace_graph_caller(void)
{
- brcl_disable(ftrace_graph_caller);
+ int rc;
+
+ /* Expect brc 0xf,... */
+ rc = ftrace_patch_branch_mask(ftrace_graph_caller, 0xa7f4, false);
+ if (rc)
+ return rc;
text_poke_sync_lock();
return 0;
}
int ftrace_disable_ftrace_graph_caller(void)
{
- brcl_enable(ftrace_graph_caller);
+ int rc;
+
+ /* Expect brc 0x0,... */
+ rc = ftrace_patch_branch_mask(ftrace_graph_caller, 0xa704, true);
+ if (rc)
+ return rc;
text_poke_sync_lock();
return 0;
}