On Mon 2019-02-18 17:22, Petr wrote:
> On Mon 2019-02-18 13:29:11, chengjian (D) wrote:
> > Hiļ¼Jiri
> >
> >
> > 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
> [email protected] 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 <[email protected]>
---
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
