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Best Regards -----邮件原件----- 发件人: chenzefeng (A) 发送时间: 2019年2月19日 14:38 收件人: 'Petr Mladek' <pmla...@suse.com>; chengjian (D) <cj.chengj...@huawei.com> 抄送: 'sta...@vger.kernel.org' <sta...@vger.kernel.org>; Jiri Kosina <ji...@kernel.org>; hjl.to...@gmail.com; jpoim...@redhat.com; sjenn...@redhat.com; vojt...@suse.com; t...@linutronix.de; mi...@redhat.com; h...@zytor.com; gre...@linuxfoundation.org; x...@kernel.org; live-patch...@vger.kernel.org; linux-kernel@vger.kernel.org; Xiexiuqi <xiexi...@huawei.com> 主题: Re:[PATCH] x86: livepatch: Treat R_X86_64_PLT32 as R_X86_64_PC32 On Mon 2019-02-18 17:22, Petr wrote: > On Mon 2019-02-18 13:29:11, chengjian (D) wrote: > > Hi，Jiri > > > > > > This patch should be merged into 4.4 stable, > > > > which still use klp_write_module_reloc. > > > > > > https://elixir.bootlin.com/linux/v4.4.174/source/arch/x86/kernel/livep > > atch.c > > > > > > ZeFeng may have sent a stable(4.4-y) patch to the wrong mail-list(mainline). > > ZeFeng or Chengjian, please, send the patch once again with > sta...@vger.kernel.org in CC and explanation that it is needed only for 4.4 > and why. > > This thread is already too long and messed to be proceed by stable people > effectively. > > Best Regards, > Petr 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 <chenzefe...@huawei.com> --- arch/x86/kernel/livepatch.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/kernel/livepatch.c b/arch/x86/kernel/livepatch.c index d1d35cc..579f8f8 100644 --- 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: -- 1.8.5.6
