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MIPS: Support R_MIPS_PC{16,21,26} rel-style relocs

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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>
This commit is contained in:
Paul Burton 2016-02-04 13:05:05 +00:00 committed by Ralf Baechle
parent ad8319ea46
commit 5d3c792583
1 changed files with 50 additions and 1 deletions
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51
arch/mips/kernel/module.c
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@ -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,