Messages in this thread Patch in this message | | | From | Kamalesh Babulal <> | Subject | [PATCH v4 2/3] powerpc/modules: Don't try to restore r2 after a sibling call | Date | Tue, 14 Nov 2017 04:29:09 -0500 |
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From: Josh Poimboeuf <jpoimboe@redhat.com>
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> Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> --- arch/powerpc/kernel/module_64.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c index 39b01fd..9e5391f 100644 --- a/arch/powerpc/kernel/module_64.c +++ b/arch/powerpc/kernel/module_64.c @@ -489,6 +489,10 @@ static int restore_r2(u32 *instruction, struct module *me) if (is_early_mcount_callsite(instruction - 1)) return 1; + /* Sibling calls don't return, so they don't need to restore r2 */ + if (instruction[-1] == PPC_INST_BRANCH) + return 1; + if (*instruction != PPC_INST_NOP) { pr_err("%s: Expect noop after relocate, got %08x\n", me->name, *instruction); -- 2.9.3
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