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Subject: [PATCH] x86: livepatch: Treat R_X86_64_PLT32 as R_X86_64_PC32
Thread-Topic: [PATCH] x86: livepatch: Treat R_X86_64_PLT32 as R_X86_64_PC32
Thread-Index: AdTE0VS6YxuMC8nAT2u21pUoQUU8yw==
Date:   Fri, 15 Feb 2019 02:01:31 +0000
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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.

In linux 4.4 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>

Signed-off-by: chenzefeng <chenzefeng2@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