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authorPaul Burton <paul.burton@imgtec.com>2016-02-04 13:05:05 +0000
committerRalf Baechle <ralf@linux-mips.org>2016-05-13 14:01:54 +0200
commit5d3c792583b6040607e178925ccc8316a207210f (patch)
tree7d632647af12f2b52553132b190c276407c54aab /arch/mips/kernel/module.c
parentad8319ea4647c897c837643a611714a83d8f6a0f (diff)
MIPS: Support R_MIPS_PC{16,21,26} rel-style relocs
MIPS32 code uses rel-style relocs, and MIPS32r6 modules may include R_MIPS_PC16, R_MIPS_PC21 & R_MIPS_PC26 relocations. We thus need to support these relocations in order to load MIPS32r6 kernel modules. This patch adds such support, which is similar to the rela-style support in module-rela.c but making use of the implicit addend from the instruction encoding. Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: Steven J. Hill <sjhill@realitydiluted.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/12435/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/kernel/module.c')
-rw-r--r--arch/mips/kernel/module.c51
1 files changed, 50 insertions, 1 deletions
diff --git a/arch/mips/kernel/module.c b/arch/mips/kernel/module.c
index e16624f57fd5..ff5d97d2e670 100644
--- a/arch/mips/kernel/module.c
+++ b/arch/mips/kernel/module.c
@@ -182,13 +182,62 @@ out_danger:
return -ENOEXEC;
}
+static int apply_r_mips_pc_rel(struct module *me, u32 *location, Elf_Addr v,
+ unsigned bits)
+{
+ unsigned long mask = GENMASK(bits - 1, 0);
+ unsigned long se_bits;
+ long offset;
+
+ if (v % 4) {
+ pr_err("module %s: dangerous R_MIPS_PC%u REL relocation\n",
+ me->name, bits);
+ return -ENOEXEC;
+ }
+
+ /* retrieve & sign extend implicit addend */
+ offset = *location & mask;
+ offset |= (offset & BIT(bits - 1)) ? ~mask : 0;
+
+ offset += ((long)v - (long)location) >> 2;
+
+ /* check the sign bit onwards are identical - ie. we didn't overflow */
+ se_bits = (offset & BIT(bits - 1)) ? ~0ul : 0;
+ if ((offset & ~mask) != (se_bits & ~mask)) {
+ pr_err("module %s: relocation overflow\n", me->name);
+ return -ENOEXEC;
+ }
+
+ *location = (*location & ~mask) | (offset & mask);
+
+ return 0;
+}
+
+static int apply_r_mips_pc16_rel(struct module *me, u32 *location, Elf_Addr v)
+{
+ return apply_r_mips_pc_rel(me, location, v, 16);
+}
+
+static int apply_r_mips_pc21_rel(struct module *me, u32 *location, Elf_Addr v)
+{
+ return apply_r_mips_pc_rel(me, location, v, 21);
+}
+
+static int apply_r_mips_pc26_rel(struct module *me, u32 *location, Elf_Addr v)
+{
+ return apply_r_mips_pc_rel(me, location, v, 26);
+}
+
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,
+ [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,