[PATCH 4/5] MIPS: Support R_MIPS_PC16 rel-style reloc

Paul Burton
2016-02-03T03:46:04Z

MIPS32 code uses rel-style relocs, and MIPS32r6 modules may include the
R_MIPS_PC16 relocation. We thus need to support R_MIPS_PC16 rel-style
relocations in order to load MIPS32r6 kernel modules. This patch adds
such support, which is similar to the rela-style R_MIPS_PC16 support but
making use of the implicit addend from the instruction encoding.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
---

arch/mips/kernel/module.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/arch/mips/kernel/module.c b/arch/mips/kernel/module.c
index 2adf572..f2de9b8 100644
--- a/arch/mips/kernel/module.c
+++ b/arch/mips/kernel/module.c
@@ -183,13 +183,25 @@ out_danger:
return -ENOEXEC;
}

+static int apply_r_mips_pc16_rel(struct module *me, u32 *location, Elf_Addr v)
+{
+ u16 val;
+
+ val = *location;
+ val += (v - (Elf_Addr)location) >> 2;
+ *location = (*location & 0xffff0000) | val;
+
+ return 0;
+}
+
static int (*reloc_handlers_rel[]) (struct module *me, u32 *location,
Elf_Addr v) = {
[R_MIPS_NONE] = apply_r_mips_none,
[R_MIPS_32] = apply_r_mips_32_rel,
[R_MIPS_26] = apply_r_mips_26_rel,
[R_MIPS_HI16] = apply_r_mips_hi16_rel,
- [R_MIPS_LO16] = apply_r_mips_lo16_rel
+ [R_MIPS_LO16] = apply_r_mips_lo16_rel,
+ [R_MIPS_PC16] = apply_r_mips_pc16_rel,
};

int apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
--
2.7.0