powerpc/kprobes: Dereference function pointers only if the address does not belong to kernel text
This makes the changes introduced in commit 83e840c770f2c5
("powerpc64/elfv1: Only dereference function descriptor for non-text
symbols") to be specific to the kprobe subsystem.
We previously changed ppc_function_entry() to always check the provided
address to confirm if it needed to be dereferenced. This is actually
only an issue for kprobe blacklisted asm labels (through use of
_ASM_NOKPROBE_SYMBOL) and can cause other issues with ftrace. Also, the
additional checks are not really necessary for our other uses.
As such, move this check to the kprobes subsystem.
Fixes: 83e840c770f2 ("powerpc64/elfv1: Only dereference function descriptor for non-text symbols")
Cc: stable@vger.kernel.org # v4.13+
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 367494d..bebc300 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -600,7 +600,12 @@
unsigned long arch_deref_entry_point(void *entry)
{
- return ppc_global_function_entry(entry);
+#ifdef PPC64_ELF_ABI_v1
+ if (!kernel_text_address((unsigned long)entry))
+ return ppc_global_function_entry(entry);
+ else
+#endif
+ return (unsigned long)entry;
}
NOKPROBE_SYMBOL(arch_deref_entry_point);
