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authorNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>2017-10-30 20:42:09 +0530
committerMichael Ellerman <mpe@ellerman.id.au>2017-11-01 15:51:03 +1100
commite6c4dcb308160115287afd87afb63b5684d75a5b (patch)
tree39f5d7025289979f52bf1c787db5102f2889995d /arch
parent63be1a81e40733ecd175713b6a7558dc43f00851 (diff)
downloadlinux-e6c4dcb308160115287afd87afb63b5684d75a5b.tar.bz2
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/kernel/kprobes.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 367494dc67d9..bebc3007a793 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -600,7 +600,12 @@ NOKPROBE_SYMBOL(kprobe_fault_handler);
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);