// SPDX-License-Identifier: GPL-2.0-or-later
/* Kernel module help for PPC.
Copyright (C) 2001 Rusty Russell.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/moduleloader.h>
#include <linux/elf.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/ftrace.h>
#include <linux/cache.h>
#include <linux/bug.h>
#include <linux/sort.h>
#include <asm/setup.h>
#include <asm/code-patching.h>
/* Count how many different relocations (different symbol, different
addend) */
static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num)
{
unsigned int i, r_info, r_addend, _count_relocs;
_count_relocs = 0;
r_info = 0;
r_addend = 0;
for (i = 0; i < num; i++)
/* Only count 24-bit relocs, others don't need stubs */
if (ELF32_R_TYPE(rela[i].r_info) == R_PPC_REL24 &&
(r_info != ELF32_R_SYM(rela[i].r_info) ||
r_addend != rela[i].r_addend)) {
_count_relocs++;
r_info = ELF32_R_SYM(rela[i].r_info);
r_addend = rela[i].r_addend;
}
#ifdef CONFIG_DYNAMIC_FTRACE
_count_relocs++; /* add one for ftrace_caller */
#endif
return _count_relocs;
}
static int relacmp(const void *_x, const void *_y)
{
const Elf32_Rela *x, *y;
y = (Elf32_Rela *)_x;
x = (Elf32_Rela *)_y;
/* Compare the entire r_info (as opposed to ELF32_R_SYM(r_info) only) to
* make the comparison cheaper/faster. It won't affect the sorting or
* the counting algorithms' performance
*/
if (x->r_info < y->r_info)
return -1;
else if (x->r_info > y->r_info)
return 1;
else if (x->r_addend < y->r_addend)
return -1;
else if (x->r_addend > y->r_addend)
return 1;
else
return 0;
}
/* Get the potential trampolines size required of the init and
non-init sections */
static unsigned long get_plt_size(const Elf32_Ehdr *hdr,
const Elf32_Shdr *sechdrs,
const char *secstrings,
int is_init)
{
unsigned long ret = 0;
unsigned i;
/* Everything marked ALLOC (this includes the exported
symbols) */
for (i = 1; i < hdr->e_shnum; i++) {
/* If it's called *.init*, and we're not init, we're
not interested */
if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != NULL)
!= is_init)
continue;
/* We don't want to look at debug sections. */
if (strstr(secstrings + sechdrs[i].sh_name, ".debug"))
continue;
if (sechdrs[i].sh_type == SHT_RELA) {
pr_debug("Found relocations in section %u\n", i);
pr_debug("Ptr: %p. Number: %u\n",
(void *)hdr + sechdrs[i].sh_offset,
sechdrs[i].sh_size / sizeof(Elf32_Rela));
/* Sort the relocation information based on a symbol and
* addend key. This is a stable O(n*log n) complexity
* algorithm but it will reduce the complexity of
* count_relocs() to linear complexity O(n)
*/
sort((void *)hdr + sechdrs[i].sh_offset,
sechdrs[i].sh_size / sizeof(Elf32_Rela),
sizeof(Elf32_Rela), relacmp, NULL);
ret += count_relocs((void *)hdr
+ sechdrs[i].sh_offset,
sechdrs[i].sh_size
/ sizeof(Elf32_Rela))
* sizeof(struct ppc_plt_entry);
}
}
return ret;
}
int module_frob_arch_sections(Elf32_Ehdr *hdr,
Elf32_Shdr *sechdrs,
char *secstrings,
struct module *me)
{
unsigned int i;
/* Find .plt and .init.plt sections */
for (i = 0; i < hdr->e_shnum; i++) {
if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0)
me->arch.init_plt_section = i;
else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0)
me->arch.core_plt_section = i;
}
if (!me->arch.core_plt_section || !me->arch.init_plt_section) {
pr_err("Module doesn't contain .plt or .init.plt sections.\n");
return -ENOEXEC;
}
/* Override their sizes */
sechdrs[me->arch.core_plt_section].sh_size
= get_plt_size(hdr, sechdrs, secstrings, 0);
sechdrs[me->arch.init_plt_section].sh_size
= get_plt_size(hdr, sechdrs, secstrings, 1);
return 0;
}
static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val)
{
if (entry->jump[0] != PPC_RAW_LIS(_R12, PPC_HA(val)))
return 0;
if (entry->jump[1] != PPC_RAW_ADDI(_R12, _R12, PPC_LO(val)))
return 0;
return 1;
}
/* Set up a trampoline in the PLT to bounce us to the distant function */
static uint32_t do_plt_call(void *location,
Elf32_Addr val,
const Elf32_Shdr *sechdrs,
struct module *mod)
{
struct ppc_plt_entry *entry;
pr_debug("Doing plt for call to 0x%x at 0x%x\n", val, (unsigned int)location);
/* Init, or core PLT? */
if (within_module_core((unsigned long)location, mod))
entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr;
else
entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr;
/* Find this entry, or if that fails, the next avail. entry */
while (entry->jump[0]) {
if (entry_matches(entry, val)) return (uint32_t)entry;
entry++;
}
if (patch_instruction(&entry->jump[0], ppc_inst(PPC_RAW_LIS(_R12, PPC_HA(val)))))
return 0;
if (patch_instruction(&entry->jump[1], ppc_inst(PPC_RAW_ADDI(_R12, _R12, PPC_LO(val)))))
return 0;
if (patch_instruction(&entry->jump[2], ppc_inst(PPC_RAW_MTCTR(_R12))))
return 0;
if (patch_instruction(&entry->jump[3], ppc_inst(PPC_RAW_BCTR())))
return 0;
pr_debug("Initialized plt for 0x%x at %p\n", val, entry);
return (uint32_t)entry;
}
static int patch_location_16(uint32_t *loc, u16 value)
{
loc = PTR_ALIGN_DOWN(loc, sizeof(u32));
return patch_instruction(loc, ppc_inst((*loc & 0xffff0000) | value));
}
int apply_relocate_add(Elf32_Shdr *sechdrs,
const char *strtab,
unsigned int symindex,
unsigned int relsec,
struct module *module)
{
unsigned int i;
Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr;
Elf32_Sym *sym;
uint32_t *location;
uint32_t value;
pr_debug("Applying ADD relocate section %u to %u\n", relsec,
sechdrs[relsec].sh_info);
for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
/* This is where to make the change */
location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
+ rela[i].r_offset;
/* This is the symbol it is referring to. Note that all
undefined symbols have been resolved. */
sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
+ ELF32_R_SYM(rela[i].r_info);
/* `Everything is relative'. */
value = sym->st_value + rela[i].r_addend;
switch (ELF32_R_TYPE(rela[i].r_info)) {
case R_PPC_ADDR32:
/* Simply set it */
*(uint32_t *)location = value;
break;
case R_PPC_ADDR16_LO:
/* Low half of the symbol */
if (patch_location_16(location, PPC_LO(value)))
return -EFAULT;
break;
case R_PPC_ADDR16_HI:
/* Higher half of the symbol */
if (patch_location_16(location, PPC_HI(value)))
return -EFAULT;
break;
case R_PPC_ADDR16_HA:
if (patch_location_16(location, PPC_HA(value)))
return -EFAULT;
break;
case R_PPC_REL24:
if ((int)(value - (uint32_t)location) < -0x02000000
|| (int)(value - (uint32_t)location) >= 0x02000000) {
value = do_plt_call(location, value,
sechdrs, module);
if (!value)
return -EFAULT;
}
/* Only replace bits 2 through 26 */
pr_debug("REL24 value = %08X. location = %08X\n",
value, (uint32_t)location);
pr_debug("Location before: %08X.\n",
*(uint32_t *)location);
value = (*(uint32_t *)location & ~PPC_LI_MASK) |
PPC_LI(value - (uint32_t)location);
if (patch_instruction(location, ppc_inst(value)))
return -EFAULT;
pr_debug("Location after: %08X.\n",
*(uint32_t *)location);
pr_debug("ie. jump to %08X+%08X = %08X\n",
*(uint32_t *)PPC_LI((uint32_t)location), (uint32_t)location,
(*(uint32_t *)PPC_LI((uint32_t)location)) + (uint32_t)location);
break;
case R_PPC_REL32:
/* 32-bit relative jump. */
*(uint32_t *)location = value - (uint32_t)location;
break;
default:
pr_err("%s: unknown ADD relocation: %u\n",
module->name,
ELF32_R_TYPE(rela[i].r_info));
return -ENOEXEC;
}
}
return 0;
}
#ifdef CONFIG_DYNAMIC_FTRACE
notrace int module_trampoline_target(struct module *mod, unsigned long addr,
unsigned long *target)
{
ppc_inst_t jmp[4];
/* Find where the trampoline jumps to */
if (copy_inst_from_kernel_nofault(jmp, (void *)addr))
return -EFAULT;
if (__copy_inst_from_kernel_nofault(jmp + 1, (void *)addr + 4))
return -EFAULT;
if (__copy_inst_from_kernel_nofault(jmp + 2, (void *)addr + 8))
return -EFAULT;
if (__copy_inst_from_kernel_nofault(jmp + 3, (void *)addr + 12))
return -EFAULT;
/* verify that this is what we expect it to be */
if ((ppc_inst_val(jmp[0]) & 0xffff0000) != PPC_RAW_LIS(_R12, 0))
return -EINVAL;
if ((ppc_inst_val(jmp[1]) & 0xffff0000) != PPC_RAW_ADDI(_R12, _R12, 0))
return -EINVAL;
if (ppc_inst_val(jmp[2]) != PPC_RAW_MTCTR(_R12))
return -EINVAL;
if (ppc_inst_val(jmp[3]) != PPC_RAW_BCTR())
return -EINVAL;
addr = (ppc_inst_val(jmp[1]) & 0xffff) | ((ppc_inst_val(jmp[0]) & 0xffff) << 16);
if (addr & 0x8000)
addr -= 0x10000;
*target = addr;
return 0;
}
int module_finalize_ftrace(struct module *module, const Elf_Shdr *sechdrs)
{
module->arch.tramp = do_plt_call(module->mem[MOD_TEXT].base,
(unsigned long)ftrace_caller,
sechdrs, module);
if (!module->arch.tramp)
return -ENOENT;
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
module->arch.tramp_regs = do_plt_call(module->mem[MOD_TEXT].base,
(unsigned long)ftrace_regs_caller,
sechdrs, module);
if (!module->arch.tramp_regs)
return -ENOENT;
#endif
return 0;
}
#endif
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