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linux-stable/arch/arm/kernel/module.c
Chen Zhongjin b6f21d14f1 ARM: 9204/2: module: Add all unwind tables when load module 
For EABI stack unwinding, when loading .ko module
the EXIDX sections will be added to a unwind_table list.

However not all EXIDX sections are added because EXIDX
sections are searched by hardcoded section names.

For functions in other sections such as .ref.text
or .kprobes.text, gcc generates seprated EXIDX sections
(such as .ARM.exidx.ref.text or .ARM.exidx.kprobes.text).

These extra EXIDX sections are not loaded, so when unwinding
functions in these sections, we will failed with:

	unwind: Index not found xxx

To fix that, I refactor the code for searching and adding
EXIDX sections:

- Check section type to search EXIDX tables (0x70000001)
instead of strcmp() the hardcoded names. Then find the
corresponding text sections by their section names.

- Add a unwind_table list in module->arch to save their own
unwind_table instead of the fixed-lenth array.

- Save .ARM.exidx.init.text section ptr, because it should
be cleaned after module init.

Now all EXIDX sections of .ko can be added correctly.

Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
2022-05-20 12:34:55 +01:00

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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/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_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;
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_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 = (offset ^ 0x8000) - 0x8000;
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);
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:
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 = (offset ^ 0x8000) - 0x8000;
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;
}
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 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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