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linux/arch/s390/kernel/module.c
Sumanth Korikkar 11458e2b3f s390/module: fix rela calculation for R_390_GOTENT 
During  module load, module layout allocation occurs by initially
allowing the architecture to frob the sections. This is performed via
module_frob_arch_sections().

However, the size of each module memory types like text,data,rodata etc
are updated correctly only after layout_sections().

After calculation of required module memory sizes for each types,
move_module() is responsible for allocating the module memory for each
type from modules vaddr range.

Considering the sequence above, module_frob_arch_sections() updates the
module mod_arch_specific got_offset before module memory text type size
is fully updated in layout_sections().  Hence mod_arch_specific
got_offset points to currently zero.

As per s390 ABI,
R_390_GOTENT :  (G + O + A - P) >> 1
where
G=me->mem[MOD_TEXT].base+me->arch.got_offset
O=info->got_offset
A=rela->r_addend
P=loc

fix R_390_GOTENT calculation in apply_rela().

Note: currently this doesn't break anything because me->arch.got_offset
is zero.  However, reordering of functions in the future could break it.

Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
2023-06-20 19:55:00 +02:00

577 lines
17 KiB
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// SPDX-License-Identifier: GPL-2.0+
/*
* Kernel module help for s390.
*
* S390 version
* Copyright IBM Corp. 2002, 2003
* Author(s): Arnd Bergmann (arndb@de.ibm.com)
* Martin Schwidefsky (schwidefsky@de.ibm.com)
*
* based on i386 version
* Copyright (C) 2001 Rusty Russell.
*/
#include <linux/module.h>
#include <linux/elf.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/ftrace.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/kasan.h>
#include <linux/moduleloader.h>
#include <linux/bug.h>
#include <linux/memory.h>
#include <asm/alternative.h>
#include <asm/nospec-branch.h>
#include <asm/facility.h>
#include <asm/ftrace.lds.h>
#include <asm/set_memory.h>
#include <asm/setup.h>
#if 0
#define DEBUGP printk
#else
#define DEBUGP(fmt , ...)
#endif
#define PLT_ENTRY_SIZE 22
static unsigned long get_module_load_offset(void)
{
static DEFINE_MUTEX(module_kaslr_mutex);
static unsigned long module_load_offset;
if (!kaslr_enabled())
return 0;
/*
* Calculate the module_load_offset the first time this code
* is called. Once calculated it stays the same until reboot.
*/
mutex_lock(&module_kaslr_mutex);
if (!module_load_offset)
module_load_offset = get_random_u32_inclusive(1, 1024) * PAGE_SIZE;
mutex_unlock(&module_kaslr_mutex);
return module_load_offset;
}
void *module_alloc(unsigned long size)
{
gfp_t gfp_mask = GFP_KERNEL;
void *p;
if (PAGE_ALIGN(size) > MODULES_LEN)
return NULL;
p = __vmalloc_node_range(size, MODULE_ALIGN,
MODULES_VADDR + get_module_load_offset(),
MODULES_END, gfp_mask, PAGE_KERNEL,
VM_FLUSH_RESET_PERMS | VM_DEFER_KMEMLEAK,
NUMA_NO_NODE, __builtin_return_address(0));
if (p && (kasan_alloc_module_shadow(p, size, gfp_mask) < 0)) {
vfree(p);
return NULL;
}
return p;
}
#ifdef CONFIG_FUNCTION_TRACER
void module_arch_cleanup(struct module *mod)
{
module_memfree(mod->arch.trampolines_start);
}
#endif
void module_arch_freeing_init(struct module *mod)
{
if (is_livepatch_module(mod) &&
mod->state == MODULE_STATE_LIVE)
return;
vfree(mod->arch.syminfo);
mod->arch.syminfo = NULL;
}
static void check_rela(Elf_Rela *rela, struct module *me)
{
struct mod_arch_syminfo *info;
info = me->arch.syminfo + ELF_R_SYM (rela->r_info);
switch (ELF_R_TYPE (rela->r_info)) {
case R_390_GOT12: /* 12 bit GOT offset. */
case R_390_GOT16: /* 16 bit GOT offset. */
case R_390_GOT20: /* 20 bit GOT offset. */
case R_390_GOT32: /* 32 bit GOT offset. */
case R_390_GOT64: /* 64 bit GOT offset. */
case R_390_GOTENT: /* 32 bit PC rel. to GOT entry shifted by 1. */
case R_390_GOTPLT12: /* 12 bit offset to jump slot. */
case R_390_GOTPLT16: /* 16 bit offset to jump slot. */
case R_390_GOTPLT20: /* 20 bit offset to jump slot. */
case R_390_GOTPLT32: /* 32 bit offset to jump slot. */
case R_390_GOTPLT64: /* 64 bit offset to jump slot. */
case R_390_GOTPLTENT: /* 32 bit rel. offset to jump slot >> 1. */
if (info->got_offset == -1UL) {
info->got_offset = me->arch.got_size;
me->arch.got_size += sizeof(void*);
}
break;
case R_390_PLT16DBL: /* 16 bit PC rel. PLT shifted by 1. */
case R_390_PLT32DBL: /* 32 bit PC rel. PLT shifted by 1. */
case R_390_PLT32: /* 32 bit PC relative PLT address. */
case R_390_PLT64: /* 64 bit PC relative PLT address. */
case R_390_PLTOFF16: /* 16 bit offset from GOT to PLT. */
case R_390_PLTOFF32: /* 32 bit offset from GOT to PLT. */
case R_390_PLTOFF64: /* 16 bit offset from GOT to PLT. */
if (info->plt_offset == -1UL) {
info->plt_offset = me->arch.plt_size;
me->arch.plt_size += PLT_ENTRY_SIZE;
}
break;
case R_390_COPY:
case R_390_GLOB_DAT:
case R_390_JMP_SLOT:
case R_390_RELATIVE:
/* Only needed if we want to support loading of
modules linked with -shared. */
break;
}
}
/*
* Account for GOT and PLT relocations. We can't add sections for
* got and plt but we can increase the core module size.
*/
int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
char *secstrings, struct module *me)
{
Elf_Shdr *symtab;
Elf_Sym *symbols;
Elf_Rela *rela;
char *strings;
int nrela, i, j;
struct module_memory *mod_mem;
/* Find symbol table and string table. */
symtab = NULL;
for (i = 0; i < hdr->e_shnum; i++)
switch (sechdrs[i].sh_type) {
case SHT_SYMTAB:
symtab = sechdrs + i;
break;
}
if (!symtab) {
printk(KERN_ERR "module %s: no symbol table\n", me->name);
return -ENOEXEC;
}
/* Allocate one syminfo structure per symbol. */
me->arch.nsyms = symtab->sh_size / sizeof(Elf_Sym);
me->arch.syminfo = vmalloc(array_size(sizeof(struct mod_arch_syminfo),
me->arch.nsyms));
if (!me->arch.syminfo)
return -ENOMEM;
symbols = (void *) hdr + symtab->sh_offset;
strings = (void *) hdr + sechdrs[symtab->sh_link].sh_offset;
for (i = 0; i < me->arch.nsyms; i++) {
if (symbols[i].st_shndx == SHN_UNDEF &&
strcmp(strings + symbols[i].st_name,
"_GLOBAL_OFFSET_TABLE_") == 0)
/* "Define" it as absolute. */
symbols[i].st_shndx = SHN_ABS;
me->arch.syminfo[i].got_offset = -1UL;
me->arch.syminfo[i].plt_offset = -1UL;
me->arch.syminfo[i].got_initialized = 0;
me->arch.syminfo[i].plt_initialized = 0;
}
/* Search for got/plt relocations. */
me->arch.got_size = me->arch.plt_size = 0;
for (i = 0; i < hdr->e_shnum; i++) {
if (sechdrs[i].sh_type != SHT_RELA)
continue;
nrela = sechdrs[i].sh_size / sizeof(Elf_Rela);
rela = (void *) hdr + sechdrs[i].sh_offset;
for (j = 0; j < nrela; j++)
check_rela(rela + j, me);
}
/* Increase core size by size of got & plt and set start
offsets for got and plt. */
mod_mem = &me->mem[MOD_TEXT];
mod_mem->size = ALIGN(mod_mem->size, 4);
me->arch.got_offset = mod_mem->size;
mod_mem->size += me->arch.got_size;
me->arch.plt_offset = mod_mem->size;
if (me->arch.plt_size) {
if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable)
me->arch.plt_size += PLT_ENTRY_SIZE;
mod_mem->size += me->arch.plt_size;
}
return 0;
}
static int apply_rela_bits(Elf_Addr loc, Elf_Addr val,
int sign, int bits, int shift,
void *(*write)(void *dest, const void *src, size_t len))
{
unsigned long umax;
long min, max;
void *dest = (void *)loc;
if (val & ((1UL << shift) - 1))
return -ENOEXEC;
if (sign) {
val = (Elf_Addr)(((long) val) >> shift);
min = -(1L << (bits - 1));
max = (1L << (bits - 1)) - 1;
if ((long) val < min || (long) val > max)
return -ENOEXEC;
} else {
val >>= shift;
umax = ((1UL << (bits - 1)) << 1) - 1;
if ((unsigned long) val > umax)
return -ENOEXEC;
}
if (bits == 8) {
unsigned char tmp = val;
write(dest, &tmp, 1);
} else if (bits == 12) {
unsigned short tmp = (val & 0xfff) |
(*(unsigned short *) loc & 0xf000);
write(dest, &tmp, 2);
} else if (bits == 16) {
unsigned short tmp = val;
write(dest, &tmp, 2);
} else if (bits == 20) {
unsigned int tmp = (val & 0xfff) << 16 |
(val & 0xff000) >> 4 | (*(unsigned int *) loc & 0xf00000ff);
write(dest, &tmp, 4);
} else if (bits == 32) {
unsigned int tmp = val;
write(dest, &tmp, 4);
} else if (bits == 64) {
unsigned long tmp = val;
write(dest, &tmp, 8);
}
return 0;
}
static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
const char *strtab, struct module *me,
void *(*write)(void *dest, const void *src, size_t len))
{
struct mod_arch_syminfo *info;
Elf_Addr loc, val;
int r_type, r_sym;
int rc = -ENOEXEC;
/* This is where to make the change */
loc = base + rela->r_offset;
/* This is the symbol it is referring to. Note that all
undefined symbols have been resolved. */
r_sym = ELF_R_SYM(rela->r_info);
r_type = ELF_R_TYPE(rela->r_info);
info = me->arch.syminfo + r_sym;
val = symtab[r_sym].st_value;
switch (r_type) {
case R_390_NONE: /* No relocation. */
rc = 0;
break;
case R_390_8: /* Direct 8 bit. */
case R_390_12: /* Direct 12 bit. */
case R_390_16: /* Direct 16 bit. */
case R_390_20: /* Direct 20 bit. */
case R_390_32: /* Direct 32 bit. */
case R_390_64: /* Direct 64 bit. */
val += rela->r_addend;
if (r_type == R_390_8)
rc = apply_rela_bits(loc, val, 0, 8, 0, write);
else if (r_type == R_390_12)
rc = apply_rela_bits(loc, val, 0, 12, 0, write);
else if (r_type == R_390_16)
rc = apply_rela_bits(loc, val, 0, 16, 0, write);
else if (r_type == R_390_20)
rc = apply_rela_bits(loc, val, 1, 20, 0, write);
else if (r_type == R_390_32)
rc = apply_rela_bits(loc, val, 0, 32, 0, write);
else if (r_type == R_390_64)
rc = apply_rela_bits(loc, val, 0, 64, 0, write);
break;
case R_390_PC16: /* PC relative 16 bit. */
case R_390_PC16DBL: /* PC relative 16 bit shifted by 1. */
case R_390_PC32DBL: /* PC relative 32 bit shifted by 1. */
case R_390_PC32: /* PC relative 32 bit. */
case R_390_PC64: /* PC relative 64 bit. */
val += rela->r_addend - loc;
if (r_type == R_390_PC16)
rc = apply_rela_bits(loc, val, 1, 16, 0, write);
else if (r_type == R_390_PC16DBL)
rc = apply_rela_bits(loc, val, 1, 16, 1, write);
else if (r_type == R_390_PC32DBL)
rc = apply_rela_bits(loc, val, 1, 32, 1, write);
else if (r_type == R_390_PC32)
rc = apply_rela_bits(loc, val, 1, 32, 0, write);
else if (r_type == R_390_PC64)
rc = apply_rela_bits(loc, val, 1, 64, 0, write);
break;
case R_390_GOT12: /* 12 bit GOT offset. */
case R_390_GOT16: /* 16 bit GOT offset. */
case R_390_GOT20: /* 20 bit GOT offset. */
case R_390_GOT32: /* 32 bit GOT offset. */
case R_390_GOT64: /* 64 bit GOT offset. */
case R_390_GOTENT: /* 32 bit PC rel. to GOT entry shifted by 1. */
case R_390_GOTPLT12: /* 12 bit offset to jump slot. */
case R_390_GOTPLT20: /* 20 bit offset to jump slot. */
case R_390_GOTPLT16: /* 16 bit offset to jump slot. */
case R_390_GOTPLT32: /* 32 bit offset to jump slot. */
case R_390_GOTPLT64: /* 64 bit offset to jump slot. */
case R_390_GOTPLTENT: /* 32 bit rel. offset to jump slot >> 1. */
if (info->got_initialized == 0) {
Elf_Addr *gotent = me->mem[MOD_TEXT].base +
me->arch.got_offset +
info->got_offset;
write(gotent, &val, sizeof(*gotent));
info->got_initialized = 1;
}
val = info->got_offset + rela->r_addend;
if (r_type == R_390_GOT12 ||
r_type == R_390_GOTPLT12)
rc = apply_rela_bits(loc, val, 0, 12, 0, write);
else if (r_type == R_390_GOT16 ||
r_type == R_390_GOTPLT16)
rc = apply_rela_bits(loc, val, 0, 16, 0, write);
else if (r_type == R_390_GOT20 ||
r_type == R_390_GOTPLT20)
rc = apply_rela_bits(loc, val, 1, 20, 0, write);
else if (r_type == R_390_GOT32 ||
r_type == R_390_GOTPLT32)
rc = apply_rela_bits(loc, val, 0, 32, 0, write);
else if (r_type == R_390_GOT64 ||
r_type == R_390_GOTPLT64)
rc = apply_rela_bits(loc, val, 0, 64, 0, write);
else if (r_type == R_390_GOTENT ||
r_type == R_390_GOTPLTENT) {
val += (Elf_Addr)me->mem[MOD_TEXT].base +
me->arch.got_offset - loc;
rc = apply_rela_bits(loc, val, 1, 32, 1, write);
}
break;
case R_390_PLT16DBL: /* 16 bit PC rel. PLT shifted by 1. */
case R_390_PLT32DBL: /* 32 bit PC rel. PLT shifted by 1. */
case R_390_PLT32: /* 32 bit PC relative PLT address. */
case R_390_PLT64: /* 64 bit PC relative PLT address. */
case R_390_PLTOFF16: /* 16 bit offset from GOT to PLT. */
case R_390_PLTOFF32: /* 32 bit offset from GOT to PLT. */
case R_390_PLTOFF64: /* 16 bit offset from GOT to PLT. */
if (info->plt_initialized == 0) {
unsigned char insn[PLT_ENTRY_SIZE];
char *plt_base;
char *ip;
plt_base = me->mem[MOD_TEXT].base + me->arch.plt_offset;
ip = plt_base + info->plt_offset;
*(int *)insn = 0x0d10e310; /* basr 1,0 */
*(int *)&insn[4] = 0x100c0004; /* lg 1,12(1) */
if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable) {
char *jump_r1;
jump_r1 = plt_base + me->arch.plt_size -
PLT_ENTRY_SIZE;
/* brcl 0xf,__jump_r1 */
*(short *)&insn[8] = 0xc0f4;
*(int *)&insn[10] = (jump_r1 - (ip + 8)) / 2;
} else {
*(int *)&insn[8] = 0x07f10000; /* br %r1 */
}
*(long *)&insn[14] = val;
write(ip, insn, sizeof(insn));
info->plt_initialized = 1;
}
if (r_type == R_390_PLTOFF16 ||
r_type == R_390_PLTOFF32 ||
r_type == R_390_PLTOFF64)
val = me->arch.plt_offset - me->arch.got_offset +
info->plt_offset + rela->r_addend;
else {
if (!((r_type == R_390_PLT16DBL &&
val - loc + 0xffffUL < 0x1ffffeUL) ||
(r_type == R_390_PLT32DBL &&
val - loc + 0xffffffffULL < 0x1fffffffeULL)))
val = (Elf_Addr) me->mem[MOD_TEXT].base +
me->arch.plt_offset +
info->plt_offset;
val += rela->r_addend - loc;
}
if (r_type == R_390_PLT16DBL)
rc = apply_rela_bits(loc, val, 1, 16, 1, write);
else if (r_type == R_390_PLTOFF16)
rc = apply_rela_bits(loc, val, 0, 16, 0, write);
else if (r_type == R_390_PLT32DBL)
rc = apply_rela_bits(loc, val, 1, 32, 1, write);
else if (r_type == R_390_PLT32 ||
r_type == R_390_PLTOFF32)
rc = apply_rela_bits(loc, val, 0, 32, 0, write);
else if (r_type == R_390_PLT64 ||
r_type == R_390_PLTOFF64)
rc = apply_rela_bits(loc, val, 0, 64, 0, write);
break;
case R_390_GOTOFF16: /* 16 bit offset to GOT. */
case R_390_GOTOFF32: /* 32 bit offset to GOT. */
case R_390_GOTOFF64: /* 64 bit offset to GOT. */
val = val + rela->r_addend -
((Elf_Addr) me->mem[MOD_TEXT].base + me->arch.got_offset);
if (r_type == R_390_GOTOFF16)
rc = apply_rela_bits(loc, val, 0, 16, 0, write);
else if (r_type == R_390_GOTOFF32)
rc = apply_rela_bits(loc, val, 0, 32, 0, write);
else if (r_type == R_390_GOTOFF64)
rc = apply_rela_bits(loc, val, 0, 64, 0, write);
break;
case R_390_GOTPC: /* 32 bit PC relative offset to GOT. */
case R_390_GOTPCDBL: /* 32 bit PC rel. off. to GOT shifted by 1. */
val = (Elf_Addr) me->mem[MOD_TEXT].base + me->arch.got_offset +
rela->r_addend - loc;
if (r_type == R_390_GOTPC)
rc = apply_rela_bits(loc, val, 1, 32, 0, write);
else if (r_type == R_390_GOTPCDBL)
rc = apply_rela_bits(loc, val, 1, 32, 1, write);
break;
case R_390_COPY:
case R_390_GLOB_DAT: /* Create GOT entry. */
case R_390_JMP_SLOT: /* Create PLT entry. */
case R_390_RELATIVE: /* Adjust by program base. */
/* Only needed if we want to support loading of
modules linked with -shared. */
return -ENOEXEC;
default:
printk(KERN_ERR "module %s: unknown relocation: %u\n",
me->name, r_type);
return -ENOEXEC;
}
if (rc) {
printk(KERN_ERR "module %s: relocation error for symbol %s "
"(r_type %i, value 0x%lx)\n",
me->name, strtab + symtab[r_sym].st_name,
r_type, (unsigned long) val);
return rc;
}
return 0;
}
static int __apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
unsigned int symindex, unsigned int relsec,
struct module *me,
void *(*write)(void *dest, const void *src, size_t len))
{
Elf_Addr base;
Elf_Sym *symtab;
Elf_Rela *rela;
unsigned long i, n;
int rc;
DEBUGP("Applying relocate section %u to %u\n",
relsec, sechdrs[relsec].sh_info);
base = sechdrs[sechdrs[relsec].sh_info].sh_addr;
symtab = (Elf_Sym *) sechdrs[symindex].sh_addr;
rela = (Elf_Rela *) sechdrs[relsec].sh_addr;
n = sechdrs[relsec].sh_size / sizeof(Elf_Rela);
for (i = 0; i < n; i++, rela++) {
rc = apply_rela(rela, base, symtab, strtab, me, write);
if (rc)
return rc;
}
return 0;
}
int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
unsigned int symindex, unsigned int relsec,
struct module *me)
{
bool early = me->state == MODULE_STATE_UNFORMED;
void *(*write)(void *, const void *, size_t) = memcpy;
if (!early)
write = s390_kernel_write;
return __apply_relocate_add(sechdrs, strtab, symindex, relsec, me,
write);
}
#ifdef CONFIG_FUNCTION_TRACER
static int module_alloc_ftrace_hotpatch_trampolines(struct module *me,
const Elf_Shdr *s)
{
char *start, *end;
int numpages;
size_t size;
size = FTRACE_HOTPATCH_TRAMPOLINES_SIZE(s->sh_size);
numpages = DIV_ROUND_UP(size, PAGE_SIZE);
start = module_alloc(numpages * PAGE_SIZE);
if (!start)
return -ENOMEM;
set_memory_rox((unsigned long)start, numpages);
end = start + size;
me->arch.trampolines_start = (struct ftrace_hotpatch_trampoline *)start;
me->arch.trampolines_end = (struct ftrace_hotpatch_trampoline *)end;
me->arch.next_trampoline = me->arch.trampolines_start;
return 0;
}
#endif /* CONFIG_FUNCTION_TRACER */
int module_finalize(const Elf_Ehdr *hdr,
const Elf_Shdr *sechdrs,
struct module *me)
{
const Elf_Shdr *s;
char *secstrings, *secname;
void *aseg;
#ifdef CONFIG_FUNCTION_TRACER
int ret;
#endif
if (IS_ENABLED(CONFIG_EXPOLINE) &&
!nospec_disable && me->arch.plt_size) {
unsigned int *ij;
ij = me->mem[MOD_TEXT].base + me->arch.plt_offset +
me->arch.plt_size - PLT_ENTRY_SIZE;
ij[0] = 0xc6000000; /* exrl %r0,.+10 */
ij[1] = 0x0005a7f4; /* j . */
ij[2] = 0x000007f1; /* br %r1 */
}
secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
aseg = (void *) s->sh_addr;
secname = secstrings + s->sh_name;
if (!strcmp(".altinstructions", secname))
/* patch .altinstructions */
apply_alternatives(aseg, aseg + s->sh_size);
if (IS_ENABLED(CONFIG_EXPOLINE) &&
(str_has_prefix(secname, ".s390_indirect")))
nospec_revert(aseg, aseg + s->sh_size);
if (IS_ENABLED(CONFIG_EXPOLINE) &&
(str_has_prefix(secname, ".s390_return")))
nospec_revert(aseg, aseg + s->sh_size);
#ifdef CONFIG_FUNCTION_TRACER
if (!strcmp(FTRACE_CALLSITE_SECTION, secname)) {
ret = module_alloc_ftrace_hotpatch_trampolines(me, s);
if (ret < 0)
return ret;
}
#endif /* CONFIG_FUNCTION_TRACER */
}
return 0;
}
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