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module.c 12.42 KiB
/*
* AArch64 loadable module support.
*
* Copyright (C) 2012 ARM Limited
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* Author: Will Deacon <will.deacon@arm.com>
*/
#include <linux/bitops.h>
#include <linux/elf.h>
#include <linux/gfp.h>
#include <linux/kasan.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/moduleloader.h>
#include <linux/vmalloc.h>
#include <asm/alternative.h>
#include <asm/insn.h>
#include <asm/sections.h>
void *module_alloc(unsigned long size)
{
gfp_t gfp_mask = GFP_KERNEL;
void *p;
/* Silence the initial allocation */
if (IS_ENABLED(CONFIG_ARM64_MODULE_PLTS))
gfp_mask |= __GFP_NOWARN;
p = __vmalloc_node_range(size, MODULE_ALIGN, module_alloc_base,
module_alloc_base + MODULES_VSIZE,
gfp_mask, PAGE_KERNEL_EXEC, 0,
NUMA_NO_NODE, __builtin_return_address(0));
if (!p && IS_ENABLED(CONFIG_ARM64_MODULE_PLTS) &&
!IS_ENABLED(CONFIG_KASAN))
/*
* KASAN can only deal with module allocations being served
* from the reserved module region, since the remainder of
* the vmalloc region is already backed by zero shadow pages,
* and punching holes into it is non-trivial. Since the module
* region is not randomized when KASAN is enabled, it is even
* less likely that the module region gets exhausted, so we
* can simply omit this fallback in that case.
*/
p = __vmalloc_node_range(size, MODULE_ALIGN, module_alloc_base,
module_alloc_base + SZ_4G, GFP_KERNEL,
PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
__builtin_return_address(0));
if (p && (kasan_module_alloc(p, size) < 0)) {
vfree(p);
return NULL;
}
return p;
}
enum aarch64_reloc_op {
RELOC_OP_NONE,
RELOC_OP_ABS,
RELOC_OP_PREL,
RELOC_OP_PAGE,
};
static u64 do_reloc(enum aarch64_reloc_op reloc_op, __le32 *place, u64 val)
{
switch (reloc_op) {
case RELOC_OP_ABS:
return val;
case RELOC_OP_PREL:
return val - (u64)place;
case RELOC_OP_PAGE:
return (val & ~0xfff) - ((u64)place & ~0xfff);
case RELOC_OP_NONE:
return 0;
}
pr_err("do_reloc: unknown relocation operation %d\n", reloc_op);
return 0;
}
static int reloc_data(enum aarch64_reloc_op op, void *place, u64 val, int len)
{
s64 sval = do_reloc(op, place, val);
switch (len) {
case 16:
*(s16 *)place = sval;
if (sval < S16_MIN || sval > U16_MAX)
return -ERANGE;
break;
case 32:
*(s32 *)place = sval;
if (sval < S32_MIN || sval > U32_MAX)
return -ERANGE;
break;
case 64:
*(s64 *)place = sval;
break;
default:
pr_err("Invalid length (%d) for data relocation\n", len);
return 0;
}
return 0;
}
enum aarch64_insn_movw_imm_type {
AARCH64_INSN_IMM_MOVNZ,
AARCH64_INSN_IMM_MOVKZ,
};
static int reloc_insn_movw(enum aarch64_reloc_op op, __le32 *place, u64 val,
int lsb, enum aarch64_insn_movw_imm_type imm_type)
{
u64 imm;
s64 sval;
u32 insn = le32_to_cpu(*place);
sval = do_reloc(op, place, val);
imm = sval >> lsb;
if (imm_type == AARCH64_INSN_IMM_MOVNZ) {
/*
* For signed MOVW relocations, we have to manipulate the
* instruction encoding depending on whether or not the
* immediate is less than zero.
*/ insn &= ~(3 << 29);
if (sval >= 0) {
/* >=0: Set the instruction to MOVZ (opcode 10b). */
insn |= 2 << 29;
} else {
/*
* <0: Set the instruction to MOVN (opcode 00b).
* Since we've masked the opcode already, we
* don't need to do anything other than
* inverting the new immediate field.
*/
imm = ~imm;
}
}
/* Update the instruction with the new encoding. */
insn = aarch64_insn_encode_immediate(AARCH64_INSN_IMM_16, insn, imm);
*place = cpu_to_le32(insn);
if (imm > U16_MAX)
return -ERANGE;
return 0;
}
static int reloc_insn_imm(enum aarch64_reloc_op op, __le32 *place, u64 val,
int lsb, int len, enum aarch64_insn_imm_type imm_type)
{
u64 imm, imm_mask;
s64 sval;
u32 insn = le32_to_cpu(*place);
/* Calculate the relocation value. */
sval = do_reloc(op, place, val);
sval >>= lsb;
/* Extract the value bits and shift them to bit 0. */
imm_mask = (BIT(lsb + len) - 1) >> lsb;
imm = sval & imm_mask;
/* Update the instruction's immediate field. */
insn = aarch64_insn_encode_immediate(imm_type, insn, imm);
*place = cpu_to_le32(insn);
/*
* Extract the upper value bits (including the sign bit) and
* shift them to bit 0.
*/
sval = (s64)(sval & ~(imm_mask >> 1)) >> (len - 1);
/*
* Overflow has occurred if the upper bits are not all equal to
* the sign bit of the value.
*/
if ((u64)(sval + 1) >= 2)
return -ERANGE;
return 0;
}
static int reloc_insn_adrp(struct module *mod, __le32 *place, u64 val)
{
u32 insn;
if (!IS_ENABLED(CONFIG_ARM64_ERRATUM_843419) ||
!cpus_have_const_cap(ARM64_WORKAROUND_843419) ||
((u64)place & 0xfff) < 0xff8)
return reloc_insn_imm(RELOC_OP_PAGE, place, val, 12, 21,
AARCH64_INSN_IMM_ADR);
/* patch ADRP to ADR if it is in range */
if (!reloc_insn_imm(RELOC_OP_PREL, place, val & ~0xfff, 0, 21,
AARCH64_INSN_IMM_ADR)) {
insn = le32_to_cpu(*place);
insn &= ~BIT(31);
} else {
/* out of range for ADR -> emit a veneer */
val = module_emit_veneer_for_adrp(mod, place, val & ~0xfff);
if (!val)
return -ENOEXEC;
insn = aarch64_insn_gen_branch_imm((u64)place, val,
AARCH64_INSN_BRANCH_NOLINK);
}
*place = cpu_to_le32(insn);
return 0;
}
int apply_relocate_add(Elf64_Shdr *sechdrs,
const char *strtab,
unsigned int symindex,
unsigned int relsec,
struct module *me)
{
unsigned int i;
int ovf;
bool overflow_check;
Elf64_Sym *sym;
void *loc;
u64 val;
Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
/* loc corresponds to P in the AArch64 ELF document. */
loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
+ rel[i].r_offset;
/* sym is the ELF symbol we're referring to. */
sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
+ ELF64_R_SYM(rel[i].r_info);
/* val corresponds to (S + A) in the AArch64 ELF document. */
val = sym->st_value + rel[i].r_addend;
/* Check for overflow by default. */
overflow_check = true;
/* Perform the static relocation. */
switch (ELF64_R_TYPE(rel[i].r_info)) {
/* Null relocations. */
case R_ARM_NONE:
case R_AARCH64_NONE:
ovf = 0;
break;
/* Data relocations. */
case R_AARCH64_ABS64:
overflow_check = false;
ovf = reloc_data(RELOC_OP_ABS, loc, val, 64);
break;
case R_AARCH64_ABS32:
ovf = reloc_data(RELOC_OP_ABS, loc, val, 32);
break;
case R_AARCH64_ABS16:
ovf = reloc_data(RELOC_OP_ABS, loc, val, 16);
break;
case R_AARCH64_PREL64:
overflow_check = false;
ovf = reloc_data(RELOC_OP_PREL, loc, val, 64);
break; case R_AARCH64_PREL32:
ovf = reloc_data(RELOC_OP_PREL, loc, val, 32);
break;
case R_AARCH64_PREL16:
ovf = reloc_data(RELOC_OP_PREL, loc, val, 16);
break;
/* MOVW instruction relocations. */
case R_AARCH64_MOVW_UABS_G0_NC:
overflow_check = false;
case R_AARCH64_MOVW_UABS_G0:
ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 0,
AARCH64_INSN_IMM_MOVKZ);
break;
case R_AARCH64_MOVW_UABS_G1_NC:
overflow_check = false;
case R_AARCH64_MOVW_UABS_G1:
ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 16,
AARCH64_INSN_IMM_MOVKZ);
break;
case R_AARCH64_MOVW_UABS_G2_NC:
overflow_check = false;
case R_AARCH64_MOVW_UABS_G2:
ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 32,
AARCH64_INSN_IMM_MOVKZ);
break;
case R_AARCH64_MOVW_UABS_G3:
/* We're using the top bits so we can't overflow. */
overflow_check = false;
ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 48,
AARCH64_INSN_IMM_MOVKZ);
break;
case R_AARCH64_MOVW_SABS_G0:
ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 0,
AARCH64_INSN_IMM_MOVNZ);
break;
case R_AARCH64_MOVW_SABS_G1:
ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 16,
AARCH64_INSN_IMM_MOVNZ);
break;
case R_AARCH64_MOVW_SABS_G2:
ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 32,
AARCH64_INSN_IMM_MOVNZ);
break;
case R_AARCH64_MOVW_PREL_G0_NC:
overflow_check = false;
ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 0,
AARCH64_INSN_IMM_MOVKZ);
break;
case R_AARCH64_MOVW_PREL_G0:
ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 0,
AARCH64_INSN_IMM_MOVNZ);
break;
case R_AARCH64_MOVW_PREL_G1_NC:
overflow_check = false;
ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 16,
AARCH64_INSN_IMM_MOVKZ);
break;
case R_AARCH64_MOVW_PREL_G1:
ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 16,
AARCH64_INSN_IMM_MOVNZ);
break;
case R_AARCH64_MOVW_PREL_G2_NC:
overflow_check = false;
ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 32,
AARCH64_INSN_IMM_MOVKZ);
break;
case R_AARCH64_MOVW_PREL_G2:
ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 32,
AARCH64_INSN_IMM_MOVNZ); break;
case R_AARCH64_MOVW_PREL_G3:
/* We're using the top bits so we can't overflow. */
overflow_check = false;
ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 48,
AARCH64_INSN_IMM_MOVNZ);
break;
/* Immediate instruction relocations. */
case R_AARCH64_LD_PREL_LO19:
ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 2, 19,
AARCH64_INSN_IMM_19);
break;
case R_AARCH64_ADR_PREL_LO21:
ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 0, 21,
AARCH64_INSN_IMM_ADR);
break;
case R_AARCH64_ADR_PREL_PG_HI21_NC:
overflow_check = false;
case R_AARCH64_ADR_PREL_PG_HI21:
ovf = reloc_insn_adrp(me, loc, val);
if (ovf && ovf != -ERANGE)
return ovf;
break;
case R_AARCH64_ADD_ABS_LO12_NC:
case R_AARCH64_LDST8_ABS_LO12_NC:
overflow_check = false;
ovf = reloc_insn_imm(RELOC_OP_ABS, loc, val, 0, 12,
AARCH64_INSN_IMM_12);
break;
case R_AARCH64_LDST16_ABS_LO12_NC:
overflow_check = false;
ovf = reloc_insn_imm(RELOC_OP_ABS, loc, val, 1, 11,
AARCH64_INSN_IMM_12);
break;
case R_AARCH64_LDST32_ABS_LO12_NC:
overflow_check = false;
ovf = reloc_insn_imm(RELOC_OP_ABS, loc, val, 2, 10,
AARCH64_INSN_IMM_12);
break;
case R_AARCH64_LDST64_ABS_LO12_NC:
overflow_check = false;
ovf = reloc_insn_imm(RELOC_OP_ABS, loc, val, 3, 9,
AARCH64_INSN_IMM_12);
break;
case R_AARCH64_LDST128_ABS_LO12_NC:
overflow_check = false;
ovf = reloc_insn_imm(RELOC_OP_ABS, loc, val, 4, 8,
AARCH64_INSN_IMM_12);
break;
case R_AARCH64_TSTBR14:
ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 2, 14,
AARCH64_INSN_IMM_14);
break;
case R_AARCH64_CONDBR19:
ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 2, 19,
AARCH64_INSN_IMM_19);
break;
case R_AARCH64_JUMP26:
case R_AARCH64_CALL26:
ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 2, 26,
AARCH64_INSN_IMM_26);
if (IS_ENABLED(CONFIG_ARM64_MODULE_PLTS) &&
ovf == -ERANGE) {
val = module_emit_plt_entry(me, loc, &rel[i], sym);
if (!val)
return -ENOEXEC;
ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 2,
26, AARCH64_INSN_IMM_26); }
break;
default:
pr_err("module %s: unsupported RELA relocation: %llu\n",
me->name, ELF64_R_TYPE(rel[i].r_info));
return -ENOEXEC;
}
if (overflow_check && ovf == -ERANGE)
goto overflow;
}
return 0;
overflow:
pr_err("module %s: overflow in relocation type %d val %Lx\n",
me->name, (int)ELF64_R_TYPE(rel[i].r_info), val);
return -ENOEXEC;
}
int module_finalize(const Elf_Ehdr *hdr,
const Elf_Shdr *sechdrs,
struct module *me)
{
const Elf_Shdr *s, *se;
const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++) {
if (strcmp(".altinstructions", secstrs + s->sh_name) == 0) {
apply_alternatives((void *)s->sh_addr, s->sh_size);
}
#ifdef CONFIG_ARM64_MODULE_PLTS
if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE) &&
!strcmp(".text.ftrace_trampoline", secstrs + s->sh_name))
me->arch.ftrace_trampoline = (void *)s->sh_addr;
#endif
}
return 0;
}