diff options
| author | Josh Poimboeuf <jpoimboe@redhat.com> | 2017-11-16 20:45:37 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2017-12-11 05:03:29 +0300 |
| commit | b9eab08d012fa093947b230f9a87257c27fb829b (patch) | |
| tree | fa5f33c519c97d9cbbf59b4598a8fdf8e8f4d273 /arch/powerpc/kernel | |
| parent | a443bf6e8a7674b86221f4922cae82d67dc9e8ad (diff) | |
| download | linux-b9eab08d012fa093947b230f9a87257c27fb829b.tar.xz | |
powerpc/modules: Don't try to restore r2 after a sibling call
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>
Diffstat (limited to 'arch/powerpc/kernel')
| -rw-r--r-- | arch/powerpc/kernel/module_64.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c index 1685b40f3935..5b44668c0e45 100644 --- a/arch/powerpc/kernel/module_64.c +++ b/arch/powerpc/kernel/module_64.c @@ -487,7 +487,17 @@ static bool is_early_mcount_callsite(u32 *instruction) restore r2. */ static int restore_r2(u32 *instruction, struct module *me) { - if (is_early_mcount_callsite(instruction - 1)) + u32 *prev_insn = instruction - 1; + + if (is_early_mcount_callsite(prev_insn)) + return 1; + + /* + * Make sure the branch isn't a sibling call. Sibling calls aren't + * "link" branches and they don't return, so they don't need the r2 + * restore afterwards. + */ + if (!instr_is_relative_link_branch(*prev_insn)) return 1; if (*instruction != PPC_INST_NOP) { |