From: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Subject: powerpc/modules: Add REL24 relocation support of livepatch symbols
Git-commit: a443bf6e8a7674b86221f4922cae82d67dc9e8ad
Patch-mainline: v4.16-rc1
References: bsc#1088321
powerpc/modules: Add REL24 relocation support of livepatch symbols
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>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Torsten Duwe <duwe@suse.de>
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index 759104b..1685b40 100644
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c
@@ -614,7 +614,8 @@ 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)