powerpc/modules: Don't try to restore r2 after a sibling call
[ Upstream commit b9eab08d012fa093947b230f9a87257c27fb829b ]
When attempting to load a livepatch module, I got the following error:
module_64: patch_module: Expect noop after relocate, got 3c820000
The error was triggered by the following code in
unregister_netdevice_queue():
14c: 00 00 00 48 b 14c <unregister_netdevice_queue+0x14c>
14c: R_PPC64_REL24 net_set_todo
150: 00 00 82 3c addis r4,r2,0
GCC didn't insert a nop after the branch to net_set_todo() because it's
a sibling call, so it never returns. The nop isn't needed after the
branch in that case.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-and-tested-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index d5edbeb..753d591 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -95,6 +95,11 @@ int instr_is_relative_branch(unsigned int instr)
return instr_is_branch_iform(instr) || instr_is_branch_bform(instr);
}
+int instr_is_relative_link_branch(unsigned int instr)
+{
+ return instr_is_relative_branch(instr) && (instr & BRANCH_SET_LINK);
+}
+
static unsigned long branch_iform_target(const unsigned int *instr)
{
signed long imm;