x86: livepatch: Treat R_X86_64_PLT32 as R_X86_64_PC32

Signed-off-by: chenzefeng <chenzefeng2@huawei.com>
On x86-64, for 32-bit PC-relacive branches, we can generate PLT32
relocation, instead of PC32 relocation. and R_X86_64_PLT32 can be
treated the same as R_X86_64_PC32 since linux kernel doesn't use PLT.

commit b21ebf2fb4cd ("x86: Treat R_X86_64_PLT32 as R_X86_64_PC32") been
fixed for the module loading, but not fixed for livepatch relocation,
which will fail to load livepatch with the error message as follow:
relocation failed for symbol <symbol name> at <symbol address>

This issue only effacted the kernel version from 4.0 to 4.6, becauce the
function klp_write_module_reloc is introduced by: commit b700e7f03df5
("livepatch: kernel: add support for live patching") and deleted by:
commit 425595a7fc20 ("livepatch: reuse module loader code to write
relocations")

Signed-off-by: chenzefeng <chenzefeng2@huawei.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kernel/livepatch.c b/arch/x86/kernel/livepatch.c
index d1d35ccffed3cab7b6caa791b91f237210183907..579f8f813ce00ad206b0c81119b8d55558e6925e 100644 (file)
--- a/arch/x86/kernel/livepatch.c
+++ b/arch/x86/kernel/livepatch.c
@@ -58,6 +58,7 @@ int klp_write_module_reloc(struct module *mod, unsigned long type,
                val = (s32)value;
                break;
        case R_X86_64_PC32:
+       case R_X86_64_PLT32:
                val = (u32)(value - loc);
                break;
        default: