[PATCH 5/5] MIPS: Implement MIPSr6 R_MIPS_PC2x rel-style relocs

Paul Burton
2016-02-03T03:46:19Z

MIPS32r6 code makes use of rel-stye relocations & may contain the new
relocations R_MIPS_PC21_S2 or R_MIPS_PC26_S2 which were introduced with
MIPSr6. Implement support for those relocations such that we can load
MIPS32r6 kernel modules.

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

---

arch/mips/kernel/module.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 52 insertions(+)

diff --git a/arch/mips/kernel/module.c b/arch/mips/kernel/module.c
index f2de9b8..d62fd56 100644
--- a/arch/mips/kernel/module.c
+++ b/arch/mips/kernel/module.c
@@ -194,6 +194,56 @@ static int apply_r_mips_pc16_rel(struct module *me, u32 *location, Elf_Addr v)
return 0;
}

+static int apply_r_mips_pc21_rel(struct module *me, u32 *location, Elf_Addr v)
+{
+ long offset;
+
+ if (v % 4) {
+ pr_err("module %s: dangerous R_MIPS_PC21 REL relocation\n",
+ me->name);
+ return -ENOEXEC;
+ }
+
+ /* retrieve & sign extend implicit addend */
+ offset = *location & 0x1fffff;
+ offset |= (offset & BIT(20)) ? (~0l & ~0x1fffffl) : 0;
+
+ offset += ((long)v - (long)location) >> 2;
+ if ((offset >> 20) > 0 || (offset >> 20) < -1) {
+ pr_err("module %s: relocation overflow\n", me->name);
+ return -ENOEXEC;
+ }
+
+ *location = (*location & ~0x001fffff) | (offset & 0x001fffff);
+
+ return 0;
+}
+
+static int apply_r_mips_pc26_rel(struct module *me, u32 *location, Elf_Addr v)
+{
+ long offset;
+
+ if (v % 4) {
+ pr_err("module %s: dangerous R_MIPS_PC26 REL relocation\n",
+ me->name);
+ return -ENOEXEC;
+ }
+
+ /* retrieve & sign extend implicit addend */
+ offset = *location & 0x3ffffff;
+ offset |= (offset & BIT(25)) ? (~0l & ~0x3ffffffl) : 0;
+
+ offset += ((long)v - (long)location) >> 2;
+ if ((offset >> 25) > 0 || (offset >> 25) < -1) {
+ pr_err("module %s: relocation overflow\n", me->name);
+ return -ENOEXEC;
+ }
+
+ *location = (*location & ~0x03ffffff) | (offset & 0x03ffffff);
+
+ return 0;
+}
+
static int (*reloc_handlers_rel[]) (struct module *me, u32 *location,
Elf_Addr v) = {
[R_MIPS_NONE] = apply_r_mips_none,
@@ -202,6 +252,8 @@ static int (*reloc_handlers_rel[]) (struct module *me, u32 *location,
[R_MIPS_HI16] = apply_r_mips_hi16_rel,
[R_MIPS_LO16] = apply_r_mips_lo16_rel,
[R_MIPS_PC16] = apply_r_mips_pc16_rel,
+ [R_MIPS_PC21_S2] = apply_r_mips_pc21_rel,
+ [R_MIPS_PC26_S2] = apply_r_mips_pc26_rel,
};

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