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x86: livepatch: Treat R_X86_64_PLT32 as R_X86_64_PC32

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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 b700e7f03d
("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>
This commit is contained in:
chenzefeng (A) 2019-02-20 12:37:54 +00:00 • committed by Greg Kroah-Hartman
parent 01fb36063d
commit f5aebe7411
1 changed files with 1 additions and 0 deletions
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arch/x86/kernel/livepatch.c
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@ -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: