| Message ID | 20171114092910.20399-2-kamalesh@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | b9eab08d012fa093947b230f9a87257c27fb829b |
| Headers | show |
| Series | ppc64le: Add REL24 relocation support of livepatch symbols | expand |
On Tue, 2017-11-14 at 09:29:08 UTC, Kamalesh Babulal wrote: > Livepatch re-uses module loader function apply_relocate_add() to write > relocations, instead of managing them by arch-dependent > klp_write_module_reloc() function. > > apply_relocate_add() doesn't understand livepatch symbols (marked with > SHN_LIVEPATCH symbol section index) and assumes them to be local symbols > by default for R_PPC64_REL24 relocation type. It fails with an error, > when trying to calculate offset with local_entry_offset(): > > module_64: kpatch_meminfo: REL24 -1152921504897399800 out of range! > > Whereas livepatch symbols are essentially SHN_UNDEF, should be > called via stub used for global calls. This issue can be fixed by > teaching apply_relocate_add() to handle both SHN_UNDEF/SHN_LIVEPATCH > symbols via the same stub. This patch extends SHN_UNDEF code to handle > livepatch symbols too. > > Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> > CC: Balbir Singh <bsingharora@gmail.com> > Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> > Cc: Josh Poimboeuf <jpoimboe@redhat.com> > Cc: Jessica Yu <jeyu@kernel.org> > Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com> > Cc: Aravinda Prasad <aravinda@linux.vnet.ibm.com> > Cc: Torsten Duwe <duwe@lst.de> Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/a443bf6e8a7674b86221f4922cae82 cheers
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c index 0b0f896..39b01fd 100644 --- a/arch/powerpc/kernel/module_64.c +++ b/arch/powerpc/kernel/module_64.c @@ -613,7 +613,8 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, case R_PPC_REL24: /* FIXME: Handle weak symbols here --RR */ - if (sym->st_shndx == SHN_UNDEF) { + if (sym->st_shndx == SHN_UNDEF || + sym->st_shndx == SHN_LIVEPATCH) { /* External: go via stub */ value = stub_for_addr(sechdrs, value, me); if (!value)
Livepatch re-uses module loader function apply_relocate_add() to write relocations, instead of managing them by arch-dependent klp_write_module_reloc() function. apply_relocate_add() doesn't understand livepatch symbols (marked with SHN_LIVEPATCH symbol section index) and assumes them to be local symbols by default for R_PPC64_REL24 relocation type. It fails with an error, when trying to calculate offset with local_entry_offset(): module_64: kpatch_meminfo: REL24 -1152921504897399800 out of range! Whereas livepatch symbols are essentially SHN_UNDEF, should be called via stub used for global calls. This issue can be fixed by teaching apply_relocate_add() to handle both SHN_UNDEF/SHN_LIVEPATCH symbols via the same stub. This patch extends SHN_UNDEF code to handle livepatch symbols too. Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> CC: Balbir Singh <bsingharora@gmail.com> Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Jessica Yu <jeyu@kernel.org> Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com> Cc: Aravinda Prasad <aravinda@linux.vnet.ibm.com> Cc: Torsten Duwe <duwe@lst.de> --- arch/powerpc/kernel/module_64.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)