AuxXxilium/linux_dsm_epyc7002
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linux_dsm_epyc7002/arch/riscv/kernel/module.c
Vincent Chen 0cff8bff7a
riscv: avoid the PIC offset of static percpu data in module beyond 2G limits 
The compiler uses the PIC-relative method to access static variables
instead of GOT when the code model is PIC. Therefore, the limitation of
the access range from the instruction to the symbol address is +-2GB.
Under this circumstance, the kernel cannot load a kernel module if this
module has static per-CPU symbols declared by DEFINE_PER_CPU(). The reason
is that kernel relocates the .data..percpu section of the kernel module to
the end of kernel's .data..percpu. Hence, the distance between the per-CPU
symbols and the instruction will exceed the 2GB limits. To solve this
problem, the kernel should place the loaded module in the memory area
[&_end-2G, VMALLOC_END].

Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
Suggested-by: Alexandre Ghiti <alex@ghiti.fr>
Suggested-by: Anup Patel <anup@brainfault.org>
Tested-by: Alexandre Ghiti <alex@ghiti.fr>
Tested-by: Carlos de Paula <me@carlosedp.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2020-03-03 10:27:45 -08:00

405 lines
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// SPDX-License-Identifier: GPL-2.0-or-later
/*
*
* Copyright (C) 2017 Zihao Yu
*/
#include <linux/elf.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/moduleloader.h>
#include <linux/vmalloc.h>
#include <linux/sizes.h>
#include <asm/pgtable.h>
#include <asm/sections.h>
static int apply_r_riscv_32_rela(struct module *me, u32 *location, Elf_Addr v)
{
if (v != (u32)v) {
pr_err("%s: value %016llx out of range for 32-bit field\n",
me->name, (long long)v);
return -EINVAL;
}
*location = v;
return 0;
}
static int apply_r_riscv_64_rela(struct module *me, u32 *location, Elf_Addr v)
{
*(u64 *)location = v;
return 0;
}
static int apply_r_riscv_branch_rela(struct module *me, u32 *location,
Elf_Addr v)
{
ptrdiff_t offset = (void *)v - (void *)location;
u32 imm12 = (offset & 0x1000) << (31 - 12);
u32 imm11 = (offset & 0x800) >> (11 - 7);
u32 imm10_5 = (offset & 0x7e0) << (30 - 10);
u32 imm4_1 = (offset & 0x1e) << (11 - 4);
*location = (*location & 0x1fff07f) | imm12 | imm11 | imm10_5 | imm4_1;
return 0;
}
static int apply_r_riscv_jal_rela(struct module *me, u32 *location,
Elf_Addr v)
{
ptrdiff_t offset = (void *)v - (void *)location;
u32 imm20 = (offset & 0x100000) << (31 - 20);
u32 imm19_12 = (offset & 0xff000);
u32 imm11 = (offset & 0x800) << (20 - 11);
u32 imm10_1 = (offset & 0x7fe) << (30 - 10);
*location = (*location & 0xfff) | imm20 | imm19_12 | imm11 | imm10_1;
return 0;
}
static int apply_r_riscv_rcv_branch_rela(struct module *me, u32 *location,
Elf_Addr v)
{
ptrdiff_t offset = (void *)v - (void *)location;
u16 imm8 = (offset & 0x100) << (12 - 8);
u16 imm7_6 = (offset & 0xc0) >> (6 - 5);
u16 imm5 = (offset & 0x20) >> (5 - 2);
u16 imm4_3 = (offset & 0x18) << (12 - 5);
u16 imm2_1 = (offset & 0x6) << (12 - 10);
*(u16 *)location = (*(u16 *)location & 0xe383) |
imm8 | imm7_6 | imm5 | imm4_3 | imm2_1;
return 0;
}
static int apply_r_riscv_rvc_jump_rela(struct module *me, u32 *location,
Elf_Addr v)
{
ptrdiff_t offset = (void *)v - (void *)location;
u16 imm11 = (offset & 0x800) << (12 - 11);
u16 imm10 = (offset & 0x400) >> (10 - 8);
u16 imm9_8 = (offset & 0x300) << (12 - 11);
u16 imm7 = (offset & 0x80) >> (7 - 6);
u16 imm6 = (offset & 0x40) << (12 - 11);
u16 imm5 = (offset & 0x20) >> (5 - 2);
u16 imm4 = (offset & 0x10) << (12 - 5);
u16 imm3_1 = (offset & 0xe) << (12 - 10);
*(u16 *)location = (*(u16 *)location & 0xe003) |
imm11 | imm10 | imm9_8 | imm7 | imm6 | imm5 | imm4 | imm3_1;
return 0;
}
static int apply_r_riscv_pcrel_hi20_rela(struct module *me, u32 *location,
Elf_Addr v)
{
ptrdiff_t offset = (void *)v - (void *)location;
s32 hi20;
if (offset != (s32)offset) {
pr_err(
"%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
me->name, (long long)v, location);
return -EINVAL;
}
hi20 = (offset + 0x800) & 0xfffff000;
*location = (*location & 0xfff) | hi20;
return 0;
}
static int apply_r_riscv_pcrel_lo12_i_rela(struct module *me, u32 *location,
Elf_Addr v)
{
/*
* v is the lo12 value to fill. It is calculated before calling this
* handler.
*/
*location = (*location & 0xfffff) | ((v & 0xfff) << 20);
return 0;
}
static int apply_r_riscv_pcrel_lo12_s_rela(struct module *me, u32 *location,
Elf_Addr v)
{
/*
* v is the lo12 value to fill. It is calculated before calling this
* handler.
*/
u32 imm11_5 = (v & 0xfe0) << (31 - 11);
u32 imm4_0 = (v & 0x1f) << (11 - 4);
*location = (*location & 0x1fff07f) | imm11_5 | imm4_0;
return 0;
}
static int apply_r_riscv_hi20_rela(struct module *me, u32 *location,
Elf_Addr v)
{
s32 hi20;
if (IS_ENABLED(CONFIG_CMODEL_MEDLOW)) {
pr_err(
"%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
me->name, (long long)v, location);
return -EINVAL;
}
hi20 = ((s32)v + 0x800) & 0xfffff000;
*location = (*location & 0xfff) | hi20;
return 0;
}
static int apply_r_riscv_lo12_i_rela(struct module *me, u32 *location,
Elf_Addr v)
{
/* Skip medlow checking because of filtering by HI20 already */
s32 hi20 = ((s32)v + 0x800) & 0xfffff000;
s32 lo12 = ((s32)v - hi20);
*location = (*location & 0xfffff) | ((lo12 & 0xfff) << 20);
return 0;
}
static int apply_r_riscv_lo12_s_rela(struct module *me, u32 *location,
Elf_Addr v)
{
/* Skip medlow checking because of filtering by HI20 already */
s32 hi20 = ((s32)v + 0x800) & 0xfffff000;
s32 lo12 = ((s32)v - hi20);
u32 imm11_5 = (lo12 & 0xfe0) << (31 - 11);
u32 imm4_0 = (lo12 & 0x1f) << (11 - 4);
*location = (*location & 0x1fff07f) | imm11_5 | imm4_0;
return 0;
}
static int apply_r_riscv_got_hi20_rela(struct module *me, u32 *location,
Elf_Addr v)
{
ptrdiff_t offset = (void *)v - (void *)location;
s32 hi20;
/* Always emit the got entry */
if (IS_ENABLED(CONFIG_MODULE_SECTIONS)) {
offset = module_emit_got_entry(me, v);
offset = (void *)offset - (void *)location;
} else {
pr_err(
"%s: can not generate the GOT entry for symbol = %016llx from PC = %p\n",
me->name, (long long)v, location);
return -EINVAL;
}
hi20 = (offset + 0x800) & 0xfffff000;
*location = (*location & 0xfff) | hi20;
return 0;
}
static int apply_r_riscv_call_plt_rela(struct module *me, u32 *location,
Elf_Addr v)
{
ptrdiff_t offset = (void *)v - (void *)location;
s32 fill_v = offset;
u32 hi20, lo12;
if (offset != fill_v) {
/* Only emit the plt entry if offset over 32-bit range */
if (IS_ENABLED(CONFIG_MODULE_SECTIONS)) {
offset = module_emit_plt_entry(me, v);
offset = (void *)offset - (void *)location;
} else {
pr_err(
"%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
me->name, (long long)v, location);
return -EINVAL;
}
}
hi20 = (offset + 0x800) & 0xfffff000;
lo12 = (offset - hi20) & 0xfff;
*location = (*location & 0xfff) | hi20;
*(location + 1) = (*(location + 1) & 0xfffff) | (lo12 << 20);
return 0;
}
static int apply_r_riscv_call_rela(struct module *me, u32 *location,
Elf_Addr v)
{
ptrdiff_t offset = (void *)v - (void *)location;
s32 fill_v = offset;
u32 hi20, lo12;
if (offset != fill_v) {
pr_err(
"%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
me->name, (long long)v, location);
return -EINVAL;
}
hi20 = (offset + 0x800) & 0xfffff000;
lo12 = (offset - hi20) & 0xfff;
*location = (*location & 0xfff) | hi20;
*(location + 1) = (*(location + 1) & 0xfffff) | (lo12 << 20);
return 0;
}
static int apply_r_riscv_relax_rela(struct module *me, u32 *location,
Elf_Addr v)
{
return 0;
}
static int apply_r_riscv_align_rela(struct module *me, u32 *location,
Elf_Addr v)
{
pr_err(
"%s: The unexpected relocation type 'R_RISCV_ALIGN' from PC = %p\n",
me->name, location);
return -EINVAL;
}
static int apply_r_riscv_add32_rela(struct module *me, u32 *location,
Elf_Addr v)
{
*(u32 *)location += (u32)v;
return 0;
}
static int apply_r_riscv_sub32_rela(struct module *me, u32 *location,
Elf_Addr v)
{
*(u32 *)location -= (u32)v;
return 0;
}
static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
Elf_Addr v) = {
[R_RISCV_32] = apply_r_riscv_32_rela,
[R_RISCV_64] = apply_r_riscv_64_rela,
[R_RISCV_BRANCH] = apply_r_riscv_branch_rela,
[R_RISCV_JAL] = apply_r_riscv_jal_rela,
[R_RISCV_RVC_BRANCH] = apply_r_riscv_rcv_branch_rela,
[R_RISCV_RVC_JUMP] = apply_r_riscv_rvc_jump_rela,
[R_RISCV_PCREL_HI20] = apply_r_riscv_pcrel_hi20_rela,
[R_RISCV_PCREL_LO12_I] = apply_r_riscv_pcrel_lo12_i_rela,
[R_RISCV_PCREL_LO12_S] = apply_r_riscv_pcrel_lo12_s_rela,
[R_RISCV_HI20] = apply_r_riscv_hi20_rela,
[R_RISCV_LO12_I] = apply_r_riscv_lo12_i_rela,
[R_RISCV_LO12_S] = apply_r_riscv_lo12_s_rela,
[R_RISCV_GOT_HI20] = apply_r_riscv_got_hi20_rela,
[R_RISCV_CALL_PLT] = apply_r_riscv_call_plt_rela,
[R_RISCV_CALL] = apply_r_riscv_call_rela,
[R_RISCV_RELAX] = apply_r_riscv_relax_rela,
[R_RISCV_ALIGN] = apply_r_riscv_align_rela,
[R_RISCV_ADD32] = apply_r_riscv_add32_rela,
[R_RISCV_SUB32] = apply_r_riscv_sub32_rela,
};
int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
unsigned int symindex, unsigned int relsec,
struct module *me)
{
Elf_Rela *rel = (void *) sechdrs[relsec].sh_addr;
int (*handler)(struct module *me, u32 *location, Elf_Addr v);
Elf_Sym *sym;
u32 *location;
unsigned int i, type;
Elf_Addr v;
int res;
pr_debug("Applying relocate section %u to %u\n", relsec,
sechdrs[relsec].sh_info);
for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
/* This is where to make the change */
location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
+ rel[i].r_offset;
/* This is the symbol it is referring to */
sym = (Elf_Sym *)sechdrs[symindex].sh_addr
+ ELF_RISCV_R_SYM(rel[i].r_info);
if (IS_ERR_VALUE(sym->st_value)) {
/* Ignore unresolved weak symbol */
if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
continue;
pr_warn("%s: Unknown symbol %s\n",
me->name, strtab + sym->st_name);
return -ENOENT;
}
type = ELF_RISCV_R_TYPE(rel[i].r_info);
if (type < ARRAY_SIZE(reloc_handlers_rela))
handler = reloc_handlers_rela[type];
else
handler = NULL;
if (!handler) {
pr_err("%s: Unknown relocation type %u\n",
me->name, type);
return -EINVAL;
}
v = sym->st_value + rel[i].r_addend;
if (type == R_RISCV_PCREL_LO12_I || type == R_RISCV_PCREL_LO12_S) {
unsigned int j;
for (j = 0; j < sechdrs[relsec].sh_size / sizeof(*rel); j++) {
unsigned long hi20_loc =
sechdrs[sechdrs[relsec].sh_info].sh_addr
+ rel[j].r_offset;
u32 hi20_type = ELF_RISCV_R_TYPE(rel[j].r_info);
/* Find the corresponding HI20 relocation entry */
if (hi20_loc == sym->st_value
&& (hi20_type == R_RISCV_PCREL_HI20
|| hi20_type == R_RISCV_GOT_HI20)) {
s32 hi20, lo12;
Elf_Sym *hi20_sym =
(Elf_Sym *)sechdrs[symindex].sh_addr
+ ELF_RISCV_R_SYM(rel[j].r_info);
unsigned long hi20_sym_val =
hi20_sym->st_value
+ rel[j].r_addend;
/* Calculate lo12 */
size_t offset = hi20_sym_val - hi20_loc;
if (IS_ENABLED(CONFIG_MODULE_SECTIONS)
&& hi20_type == R_RISCV_GOT_HI20) {
offset = module_emit_got_entry(
me, hi20_sym_val);
offset = offset - hi20_loc;
}
hi20 = (offset + 0x800) & 0xfffff000;
lo12 = offset - hi20;
v = lo12;
break;
}
}
if (j == sechdrs[relsec].sh_size / sizeof(*rel)) {
pr_err(
"%s: Can not find HI20 relocation information\n",
me->name);
return -EINVAL;
}
}
res = handler(me, location, v);
if (res)
return res;
}
return 0;
}
#if defined(CONFIG_MMU) && defined(CONFIG_64BIT)
#define VMALLOC_MODULE_START \
max(PFN_ALIGN((unsigned long)&_end - SZ_2G), VMALLOC_START)
void *module_alloc(unsigned long size)
{
return __vmalloc_node_range(size, 1, VMALLOC_MODULE_START,
VMALLOC_END, GFP_KERNEL,
PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
__builtin_return_address(0));
}
#endif
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