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

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MIPS64 code uses rela-style relocs, and MIPS64r6 modules may include the
new R_MIPS_PC21 & R_MIPS_PC26 relocations. We thus need to support these
relocations in order to load MIPS64r6 kernel modules. They are similar
to the existing R_MIPS_PC16 relocation but applying to a wider field.
Implement support for them by genericising the existing R_MIPS_PC16
implementation such that it can be used for different field widths, and
calling it for all 3 reloc types.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Maciej W. Rozycki <macro@imgtec.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Alex Smith <alex.smith@imgtec.com>
Cc: Steven J. Hill <sjhill@realitydiluted.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/12434/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Paul Burton 2016-02-04 13:05:04 +00:00 committed by Ralf Baechle
parent 55d791f37c
commit ad8319ea46
2 changed files with 52 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
arch/mips/include/asm/elf.h
View File

@ -110,6 +110,11 @@
*/
#define R_MIPS_CALLHI16 30
#define R_MIPS_CALLLO16 31
/*
* Introduced for MIPSr6.
*/
#define R_MIPS_PC21_S2 60
#define R_MIPS_PC26_S2 61
/*
* This range is reserved for vendor specific relocations.
*/

48
arch/mips/kernel/module-rela.c
View File

@ -16,6 +16,7 @@
* Copyright (C) 2001 Rusty Russell.
* Copyright (C) 2003, 2004 Ralf Baechle (ralf@linux-mips.org)
* Copyright (C) 2005 Thiemo Seufer
* Copyright (C) 2015 Imagination Technologies Ltd.
*/
#include <linux/elf.h>
@ -65,6 +66,48 @@ static int apply_r_mips_lo16_rela(struct module *me, u32 *location, Elf_Addr v)
return 0;
}
static int apply_r_mips_pc_rela(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 RELA relocation\n",
me->name, bits);
return -ENOEXEC;
}
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_rela(struct module *me, u32 *location, Elf_Addr v)
{
return apply_r_mips_pc_rela(me, location, v, 16);
}
static int apply_r_mips_pc21_rela(struct module *me, u32 *location, Elf_Addr v)
{
return apply_r_mips_pc_rela(me, location, v, 21);
}
static int apply_r_mips_pc26_rela(struct module *me, u32 *location, Elf_Addr v)
{
return apply_r_mips_pc_rela(me, location, v, 26);
}
static int apply_r_mips_64_rela(struct module *me, u32 *location, Elf_Addr v)
{
*(Elf_Addr *)location = v;
@ -97,9 +140,12 @@ static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
[R_MIPS_26] = apply_r_mips_26_rela,
[R_MIPS_HI16] = apply_r_mips_hi16_rela,
[R_MIPS_LO16] = apply_r_mips_lo16_rela,
[R_MIPS_PC16] = apply_r_mips_pc16_rela,
[R_MIPS_64] = apply_r_mips_64_rela,
[R_MIPS_HIGHER] = apply_r_mips_higher_rela,
[R_MIPS_HIGHEST] = apply_r_mips_highest_rela
[R_MIPS_HIGHEST] = apply_r_mips_highest_rela,
[R_MIPS_PC21_S2] = apply_r_mips_pc21_rela,
[R_MIPS_PC26_S2] = apply_r_mips_pc26_rela,
};
int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,