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linux/arch/arm/kernel/module.c

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// 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/vmalloc.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/gfp.h>
#include <asm/pgtable.h>
#include <asm/sections.h>
#include <asm/smp_plat.h>
#include <asm/unwind.h>
#include <asm/opcodes.h>
#ifdef CONFIG_XIP_KERNEL
/*
* The XIP kernel text is mapped in the module area for modules and
* some other stuff to work without any indirect relocations.
* MODULES_VADDR is redefined here and not in asm/memory.h to avoid
* recompiling the whole kernel when CONFIG_XIP_KERNEL is turned on/off.
*/
#undef MODULES_VADDR
#define MODULES_VADDR (((unsigned long)_exiprom + ~PMD_MASK) & PMD_MASK)
#endif
#ifdef CONFIG_MMU
void *module_alloc(unsigned long size)
{
gfp_t gfp_mask = GFP_KERNEL;
void *p;
/* Silence the initial allocation */
if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS))
gfp_mask |= __GFP_NOWARN;
p = __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
gfp_mask, PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
__builtin_return_address(0));
if (!IS_ENABLED(CONFIG_ARM_MODULE_PLTS) || p)
return p;
return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END,
GFP_KERNEL, PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
__builtin_return_address(0));
}
#endif
bool module_exit_section(const char *name)
{
return strstarts(name, ".exit") ||
strstarts(name, ".ARM.extab.exit") ||
strstarts(name, ".ARM.exidx.exit");
}
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;
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;
if (offset & 0x02000000)
offset -= 0x04000000;
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_MOVW_ABS_NC:
case R_ARM_MOVT_ABS:
offset = tmp = __mem_to_opcode_arm(*(u32 *)loc);
offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
offset = (offset ^ 0x8000) - 0x8000;
offset += sym->st_value;
if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_ABS)
offset >>= 16;
tmp &= 0xfff0f000;
tmp |= ((offset & 0xf000) << 4) |
(offset & 0x0fff);
*(u32 *)loc = __opcode_to_mem_arm(tmp);
break;
#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);
if (offset & 0x01000000)
offset -= 0x02000000;
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:
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 = (offset ^ 0x8000) - 0x8000;
offset += sym->st_value;
if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_ABS)
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;
}
struct mod_unwind_map {
const Elf_Shdr *unw_sec;
const Elf_Shdr *txt_sec;
};
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 mod_unwind_map maps[ARM_SEC_MAX];
int i;
memset(maps, 0, sizeof(maps));
for (s = sechdrs; s < sechdrs_end; s++) {
const char *secname = secstrs + s->sh_name;
if (!(s->sh_flags & SHF_ALLOC))
continue;
if (strcmp(".ARM.exidx.init.text", secname) == 0)
maps[ARM_SEC_INIT].unw_sec = s;
else if (strcmp(".ARM.exidx", secname) == 0)
maps[ARM_SEC_CORE].unw_sec = s;
else if (strcmp(".ARM.exidx.exit.text", secname) == 0)
maps[ARM_SEC_EXIT].unw_sec = s;
else if (strcmp(".ARM.exidx.text.unlikely", secname) == 0)
maps[ARM_SEC_UNLIKELY].unw_sec = s;
else if (strcmp(".ARM.exidx.text.hot", secname) == 0)
maps[ARM_SEC_HOT].unw_sec = s;
else if (strcmp(".init.text", secname) == 0)
maps[ARM_SEC_INIT].txt_sec = s;
else if (strcmp(".text", secname) == 0)
maps[ARM_SEC_CORE].txt_sec = s;
else if (strcmp(".exit.text", secname) == 0)
maps[ARM_SEC_EXIT].txt_sec = s;
else if (strcmp(".text.unlikely", secname) == 0)
maps[ARM_SEC_UNLIKELY].txt_sec = s;
else if (strcmp(".text.hot", secname) == 0)
maps[ARM_SEC_HOT].txt_sec = s;
}
for (i = 0; i < ARM_SEC_MAX; i++)
if (maps[i].unw_sec && maps[i].txt_sec)
mod->arch.unwind[i] =
unwind_table_add(maps[i].unw_sec->sh_addr,
maps[i].unw_sec->sh_size,
maps[i].txt_sec->sh_addr,
maps[i].txt_sec->sh_size);
#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
int i;
for (i = 0; i < ARM_SEC_MAX; i++)
if (mod->arch.unwind[i])
unwind_table_del(mod->arch.unwind[i]);
#endif
}
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