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s390/ftrace: Use get/copy_from_kernel_nofault consistently

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Use get/copy_from_kernel_nofault to access the kernel text consistently.
Replace memcmp() in ftrace_init_nop() to ensure that in case of
inconsistencies in the 'mcount' table, the kernel reports a failure
instead of potentially crashing.

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Vasily Gorbik 2024-08-28 19:06:58 +02:00
parent efd9cd019e
commit 5200614080
1 changed files with 5 additions and 2 deletions
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7
arch/s390/kernel/ftrace.c
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@ -76,12 +76,13 @@ int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
{
static struct ftrace_hotpatch_trampoline *next_vmlinux_trampoline =
__ftrace_hotpatch_trampolines_start;
static const char orig[6] = { 0xc0, 0x04, 0x00, 0x00, 0x00, 0x00 };
static const struct ftrace_insn orig = { .opc = 0xc004, .disp = 0 };
static struct ftrace_hotpatch_trampoline *trampoline;
struct ftrace_hotpatch_trampoline **next_trampoline;
struct ftrace_hotpatch_trampoline *trampolines_end;
struct ftrace_hotpatch_trampoline tmp;
struct ftrace_insn *insn;
struct ftrace_insn old;
const char *shared;
s32 disp;
@ -102,8 +103,10 @@ int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
return -ENOMEM;
trampoline = (*next_trampoline)++;
if (copy_from_kernel_nofault(&old, (void *)rec->ip, sizeof(old)))
return -EFAULT;
/* Check for the compiler-generated fentry nop (brcl 0, .). */
if (WARN_ON_ONCE(memcmp((const void *)rec->ip, &orig, sizeof(orig))))
if (WARN_ON_ONCE(memcmp(&orig, &old, sizeof(old))))
return -EINVAL;
/* Generate the trampoline. */