// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/arch/arm/kernel/module.c
*
* Copyright (C) 2002 Russell King.
* Modified for nommu by Hyok S. Choi
*
* Module allocation method suggested by Andi Kleen.
*/
#include <linux/module.h>
#include <linux/moduleloader.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/elf.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <asm/sections.h>
#include <asm/smp_plat.h>
#include <asm/unwind.h>
#include <asm/opcodes.h>
bool module_init_section(const char *name)
{
return strstarts(name, ".init") ||
strstarts(name, ".ARM.extab.init") ||
strstarts(name, ".ARM.exidx.init");
}
bool module_exit_section(const char *name)
{
return strstarts(name, ".exit") ||
strstarts(name, ".ARM.extab.exit") ||
strstarts(name, ".ARM.exidx.exit");
}
#ifdef CONFIG_ARM_HAS_GROUP_RELOCS
/*
* This implements the partitioning algorithm for group relocations as
* documented in the ARM AArch32 ELF psABI (IHI 0044).
*
* A single PC-relative symbol reference is divided in up to 3 add or subtract
* operations, where the final one could be incorporated into a load/store
* instruction with immediate offset. E.g.,
*
* ADD Rd, PC, #... or ADD Rd, PC, #...
* ADD Rd, Rd, #... ADD Rd, Rd, #...
* LDR Rd, [Rd, #...] ADD Rd, Rd, #...
*
* The latter has a guaranteed range of only 16 MiB (3x8 == 24 bits), so it is
* of limited use in the kernel. However, the ADD/ADD/LDR combo has a range of
* -/+ 256 MiB, (2x8 + 12 == 28 bits), which means it has sufficient range for
* any in-kernel symbol reference (unless module PLTs are being used).
*
* The main advantage of this approach over the typical pattern using a literal
* load is that literal loads may miss in the D-cache, and generally lead to
* lower cache efficiency for variables that are referenced often from many
* different places in the code.
*/
static u32 get_group_rem(u32 group, u32 *offset)
{
u32 val = *offset;
u32 shift;
do {
shift = val ? (31 - __fls(val)) & ~1 : 32;
*offset = val;
if (!val)
break;
val &= 0xffffff >> shift;
} while (group--);
return shift;
}
#endif
int
apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
unsigned int relindex, struct module *module)
{
Elf32_Shdr *symsec = sechdrs + symindex;
Elf32_Shdr *relsec = sechdrs + relindex;
Elf32_Shdr *dstsec = sechdrs + relsec->sh_info;
Elf32_Rel *rel = (void *)relsec->sh_addr;
unsigned int i;
for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rel); i++, rel++) {
unsigned long loc;
Elf32_Sym *sym;
const char *symname;
#ifdef CONFIG_ARM_HAS_GROUP_RELOCS
u32 shift, group = 1;
#endif
s32 offset;
u32 tmp;
#ifdef CONFIG_THUMB2_KERNEL
u32 upper, lower, sign, j1, j2;
#endif
offset = ELF32_R_SYM(rel->r_info);
if (offset < 0 || offset > (symsec->sh_size / sizeof(Elf32_Sym))) {
pr_err("%s: section %u reloc %u: bad relocation sym offset\n",
module->name, relindex, i);
return -ENOEXEC;
}
sym = ((Elf32_Sym *)symsec->sh_addr) + offset;
symname = strtab + sym->st_name;
if (rel->r_offset < 0 || rel->r_offset > dstsec->sh_size - sizeof(u32)) {
pr_err("%s: section %u reloc %u sym '%s': out of bounds relocation, offset %d size %u\n",
module->name, relindex, i, symname,
rel->r_offset, dstsec->sh_size);
return -ENOEXEC;
}
loc = dstsec->sh_addr + rel->r_offset;
switch (ELF32_R_TYPE(rel->r_info)) {
case R_ARM_NONE:
/* ignore */
break;
case R_ARM_ABS32:
case R_ARM_TARGET1:
*(u32 *)loc += sym->st_value;
break;
case R_ARM_PC24:
case R_ARM_CALL:
case R_ARM_JUMP24:
if (sym->st_value & 3) {
pr_err("%s: section %u reloc %u sym '%s': unsupported interworking call (ARM -> Thumb)\n",
module->name, relindex, i, symname);
return -ENOEXEC;
}
offset = __mem_to_opcode_arm(*(u32 *)loc);
offset = (offset & 0x00ffffff) << 2;
offset = sign_extend32(offset, 25);
offset += sym->st_value - loc;
/*
* Route through a PLT entry if 'offset' exceeds the
* supported range. Note that 'offset + loc + 8'
* contains the absolute jump target, i.e.,
* @sym + addend, corrected for the +8 PC bias.
*/
if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS) &&
(offset <= (s32)0xfe000000 ||
offset >= (s32)0x02000000))
offset = get_module_plt(module, loc,
offset + loc + 8)
- loc - 8;
if (offset <= (s32)0xfe000000 ||
offset >= (s32)0x02000000) {
pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
module->name, relindex, i, symname,
ELF32_R_TYPE(rel->r_info), loc,
sym->st_value);
return -ENOEXEC;
}
offset >>= 2;
offset &= 0x00ffffff;
*(u32 *)loc &= __opcode_to_mem_arm(0xff000000);
*(u32 *)loc |= __opcode_to_mem_arm(offset);
break;
case R_ARM_V4BX:
/* Preserve Rm and the condition code. Alter
* other bits to re-code instruction as
* MOV PC,Rm.
*/
*(u32 *)loc &= __opcode_to_mem_arm(0xf000000f);
*(u32 *)loc |= __opcode_to_mem_arm(0x01a0f000);
break;
case R_ARM_PREL31:
offset = (*(s32 *)loc << 1) >> 1; /* sign extend */
offset += sym->st_value - loc;
if (offset >= 0x40000000 || offset < -0x40000000) {
pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
module->name, relindex, i, symname,
ELF32_R_TYPE(rel->r_info), loc,
sym->st_value);
return -ENOEXEC;
}
*(u32 *)loc &= 0x80000000;
*(u32 *)loc |= offset & 0x7fffffff;
break;
case R_ARM_REL32:
*(u32 *)loc += sym->st_value - loc;
break;
case R_ARM_MOVW_ABS_NC:
case R_ARM_MOVT_ABS:
case R_ARM_MOVW_PREL_NC:
case R_ARM_MOVT_PREL:
offset = tmp = __mem_to_opcode_arm(*(u32 *)loc);
offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
offset = sign_extend32(offset, 15);
offset += sym->st_value;
if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_PREL ||
ELF32_R_TYPE(rel->r_info) == R_ARM_MOVW_PREL_NC)
offset -= loc;
if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_ABS ||
ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_PREL)
offset >>= 16;
tmp &= 0xfff0f000;
tmp |= ((offset & 0xf000) << 4) |
(offset & 0x0fff);
*(u32 *)loc = __opcode_to_mem_arm(tmp);
break;
#ifdef CONFIG_ARM_HAS_GROUP_RELOCS
case R_ARM_ALU_PC_G0_NC:
group = 0;
fallthrough;
case R_ARM_ALU_PC_G1_NC:
tmp = __mem_to_opcode_arm(*(u32 *)loc);
offset = ror32(tmp & 0xff, (tmp & 0xf00) >> 7);
if (tmp & BIT(22))
offset = -offset;
offset += sym->st_value - loc;
if (offset < 0) {
offset = -offset;
tmp = (tmp & ~BIT(23)) | BIT(22); // SUB opcode
} else {
tmp = (tmp & ~BIT(22)) | BIT(23); // ADD opcode
}
shift = get_group_rem(group, &offset);
if (shift < 24) {
offset >>= 24 - shift;
offset |= (shift + 8) << 7;
}
*(u32 *)loc = __opcode_to_mem_arm((tmp & ~0xfff) | offset);
break;
case R_ARM_LDR_PC_G2:
tmp = __mem_to_opcode_arm(*(u32 *)loc);
offset = tmp & 0xfff;
if (~tmp & BIT(23)) // U bit cleared?
offset = -offset;
offset += sym->st_value - loc;
if (offset < 0) {
offset = -offset;
tmp &= ~BIT(23); // clear U bit
} else {
tmp |= BIT(23); // set U bit
}
get_group_rem(2, &offset);
if (offset > 0xfff) {
pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
module->name, relindex, i, symname,
ELF32_R_TYPE(rel->r_info), loc,
sym->st_value);
return -ENOEXEC;
}
*(u32 *)loc = __opcode_to_mem_arm((tmp & ~0xfff) | offset);
break;
#endif
#ifdef CONFIG_THUMB2_KERNEL
case R_ARM_THM_CALL:
case R_ARM_THM_JUMP24:
/*
* For function symbols, only Thumb addresses are
* allowed (no interworking).
*
* For non-function symbols, the destination
* has no specific ARM/Thumb disposition, so
* the branch is resolved under the assumption
* that interworking is not required.
*/
if (ELF32_ST_TYPE(sym->st_info) == STT_FUNC &&
!(sym->st_value & 1)) {
pr_err("%s: section %u reloc %u sym '%s': unsupported interworking call (Thumb -> ARM)\n",
module->name, relindex, i, symname);
return -ENOEXEC;
}
upper = __mem_to_opcode_thumb16(*(u16 *)loc);
lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2));
/*
* 25 bit signed address range (Thumb-2 BL and B.W
* instructions):
* S:I1:I2:imm10:imm11:0
* where:
* S = upper[10] = offset[24]
* I1 = ~(J1 ^ S) = offset[23]
* I2 = ~(J2 ^ S) = offset[22]
* imm10 = upper[9:0] = offset[21:12]
* imm11 = lower[10:0] = offset[11:1]
* J1 = lower[13]
* J2 = lower[11]
*/
sign = (upper >> 10) & 1;
j1 = (lower >> 13) & 1;
j2 = (lower >> 11) & 1;
offset = (sign << 24) | ((~(j1 ^ sign) & 1) << 23) |
((~(j2 ^ sign) & 1) << 22) |
((upper & 0x03ff) << 12) |
((lower & 0x07ff) << 1);
offset = sign_extend32(offset, 24);
offset += sym->st_value - loc;
/*
* Route through a PLT entry if 'offset' exceeds the
* supported range.
*/
if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS) &&
(offset <= (s32)0xff000000 ||
offset >= (s32)0x01000000))
offset = get_module_plt(module, loc,
offset + loc + 4)
- loc - 4;
if (offset <= (s32)0xff000000 ||
offset >= (s32)0x01000000) {
pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
module->name, relindex, i, symname,
ELF32_R_TYPE(rel->r_info), loc,
sym->st_value);
return -ENOEXEC;
}
sign = (offset >> 24) & 1;
j1 = sign ^ (~(offset >> 23) & 1);
j2 = sign ^ (~(offset >> 22) & 1);
upper = (u16)((upper & 0xf800) | (sign << 10) |
((offset >> 12) & 0x03ff));
lower = (u16)((lower & 0xd000) |
(j1 << 13) | (j2 << 11) |
((offset >> 1) & 0x07ff));
*(u16 *)loc = __opcode_to_mem_thumb16(upper);
*(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower);
break;
case R_ARM_THM_MOVW_ABS_NC:
case R_ARM_THM_MOVT_ABS:
case R_ARM_THM_MOVW_PREL_NC:
case R_ARM_THM_MOVT_PREL:
upper = __mem_to_opcode_thumb16(*(u16 *)loc);
lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2));
/*
* MOVT/MOVW instructions encoding in Thumb-2:
*
* i = upper[10]
* imm4 = upper[3:0]
* imm3 = lower[14:12]
* imm8 = lower[7:0]
*
* imm16 = imm4:i:imm3:imm8
*/
offset = ((upper & 0x000f) << 12) |
((upper & 0x0400) << 1) |
((lower & 0x7000) >> 4) | (lower & 0x00ff);
offset = sign_extend32(offset, 15);
offset += sym->st_value;
if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_PREL ||
ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVW_PREL_NC)
offset -= loc;
if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_ABS ||
ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_PREL)
offset >>= 16;
upper = (u16)((upper & 0xfbf0) |
((offset & 0xf000) >> 12) |
((offset & 0x0800) >> 1));
lower = (u16)((lower & 0x8f00) |
((offset & 0x0700) << 4) |
(offset & 0x00ff));
*(u16 *)loc = __opcode_to_mem_thumb16(upper);
*(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower);
break;
#endif
default:
pr_err("%s: unknown relocation: %u\n",
module->name, ELF32_R_TYPE(rel->r_info));
return -ENOEXEC;
}
}
return 0;
}
static const Elf_Shdr *find_mod_section(const Elf32_Ehdr *hdr,
const Elf_Shdr *sechdrs, const char *name)
{
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(name, secstrs + s->sh_name) == 0)
return s;
return NULL;
}
extern void fixup_pv_table(const void *, unsigned long);
extern void fixup_smp(const void *, unsigned long);
int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
struct module *mod)
{
const Elf_Shdr *s = NULL;
#ifdef CONFIG_ARM_UNWIND
const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
const Elf_Shdr *sechdrs_end = sechdrs + hdr->e_shnum;
struct list_head *unwind_list = &mod->arch.unwind_list;
INIT_LIST_HEAD(unwind_list);
mod->arch.init_table = NULL;
for (s = sechdrs; s < sechdrs_end; s++) {
const char *secname = secstrs + s->sh_name;
const char *txtname;
const Elf_Shdr *txt_sec;
if (!(s->sh_flags & SHF_ALLOC) ||
s->sh_type != ELF_SECTION_UNWIND)
continue;
if (!strcmp(".ARM.exidx", secname))
txtname = ".text";
else
txtname = secname + strlen(".ARM.exidx");
txt_sec = find_mod_section(hdr, sechdrs, txtname);
if (txt_sec) {
struct unwind_table *table =
unwind_table_add(s->sh_addr,
s->sh_size,
txt_sec->sh_addr,
txt_sec->sh_size);
list_add(&table->mod_list, unwind_list);
/* save init table for module_arch_freeing_init */
if (strcmp(".ARM.exidx.init.text", secname) == 0)
mod->arch.init_table = table;
}
}
#endif
#ifdef CONFIG_ARM_PATCH_PHYS_VIRT
s = find_mod_section(hdr, sechdrs, ".pv_table");
if (s)
fixup_pv_table((void *)s->sh_addr, s->sh_size);
#endif
s = find_mod_section(hdr, sechdrs, ".alt.smp.init");
if (s && !is_smp())
#ifdef CONFIG_SMP_ON_UP
fixup_smp((void *)s->sh_addr, s->sh_size);
#else
return -EINVAL;
#endif
return 0;
}
void
module_arch_cleanup(struct module *mod)
{
#ifdef CONFIG_ARM_UNWIND
struct unwind_table *tmp;
struct unwind_table *n;
list_for_each_entry_safe(tmp, n,
&mod->arch.unwind_list, mod_list) {
list_del(&tmp->mod_list);
unwind_table_del(tmp);
}
mod->arch.init_table = NULL;
#endif
}
void __weak module_arch_freeing_init(struct module *mod)
{
#ifdef CONFIG_ARM_UNWIND
struct unwind_table *init = mod->arch.init_table;
if (init) {
mod->arch.init_table = NULL;
list_del(&init->mod_list);
unwind_table_del(init);
}
#endif
}
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