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LoongArch: Support modules with new relocation types
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If GAS 2.40 and/or GCC 13 is used to build the kernel, the modules will
contain R_LARCH_B26, R_LARCH_PCALA_HI20, R_LARCH_PCALA_LO12,
R_LARCH_GOT_PC_HI20, and R_LARCH_GOT_PC_LO12 relocations.  Support them
in the module loader to allow a kernel built with latest toolchain
capable to load the modules.

Signed-off-by: Xi Ruoyao <xry111@xry111.site>
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@xry111 @intel-lab-lkp
xry111 authored and intel-lab-lkp committed Jul 27, 2022
1 parent 91e3309 commit befc276
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Showing 3 changed files with 130 additions and 2 deletions.
37 changes: 37 additions & 0 deletions arch/loongarch/include/asm/elf.h
View file
Expand Up @@ -74,6 +74,43 @@
#define R_LARCH_SUB64 56
#define R_LARCH_GNU_VTINHERIT 57
#define R_LARCH_GNU_VTENTRY 58
#define R_LARCH_B16 64
#define R_LARCH_B21 65
#define R_LARCH_B26 66
#define R_LARCH_ABS_HI20 67
#define R_LARCH_ABS_LO12 68
#define R_LARCH_ABS64_LO20 69
#define R_LARCH_ABS64_HI12 70
#define R_LARCH_PCALA_HI20 71
#define R_LARCH_PCALA_LO12 72
#define R_LARCH_PCALA64_LO20 73
#define R_LARCH_PCALA64_HI12 74
#define R_LARCH_GOT_PC_HI20 75
#define R_LARCH_GOT_PC_LO12 76
#define R_LARCH_GOT64_PC_LO20 77
#define R_LARCH_GOT64_PC_HI12 78
#define R_LARCH_GOT_HI20 79
#define R_LARCH_GOT_LO12 80
#define R_LARCH_GOT64_LO20 81
#define R_LARCH_GOT64_HI12 82
#define R_LARCH_TLS_LE_HI20 83
#define R_LARCH_TLS_LE_LO12 84
#define R_LARCH_TLS_LE64_LO20 85
#define R_LARCH_TLS_LE64_HI12 86
#define R_LARCH_TLS_IE_PC_HI20 87
#define R_LARCH_TLS_IE_PC_LO12 88
#define R_LARCH_TLS_IE64_PC_LO20 89
#define R_LARCH_TLS_IE64_PC_HI12 90
#define R_LARCH_TLS_IE_HI20 91
#define R_LARCH_TLS_IE_LO12 92
#define R_LARCH_TLS_IE64_LO20 93
#define R_LARCH_TLS_IE64_HI12 94
#define R_LARCH_TLS_LD_PC_HI20 95
#define R_LARCH_TLS_LD_HI20 96
#define R_LARCH_TLS_GD_PC_HI20 97
#define R_LARCH_TLS_GD_HI20 98
#define R_LARCH_32_PCREL 99
#define R_LARCH_RELAX 100

#ifndef ELF_ARCH

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12 changes: 10 additions & 2 deletions arch/loongarch/kernel/module-sections.c
View file
Expand Up @@ -76,12 +76,20 @@ static void count_max_entries(Elf_Rela *relas, int num,

for (i = 0; i < num; i++) {
type = ELF_R_TYPE(relas[i].r_info);
if (type == R_LARCH_SOP_PUSH_PLT_PCREL) {
switch (type) {
case R_LARCH_SOP_PUSH_PLT_PCREL:
case R_LARCH_B26:
if (!duplicate_rela(relas, i))
(*plts)++;
} else if (type == R_LARCH_SOP_PUSH_GPREL)
break;
case R_LARCH_SOP_PUSH_GPREL:
case R_LARCH_GOT_PC_HI20:
if (!duplicate_rela(relas, i))
(*gots)++;
break;
default:
/* Do nothing. */
}
}
}

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83 changes: 83 additions & 0 deletions arch/loongarch/kernel/module.c
View file
Expand Up @@ -291,6 +291,84 @@ static int apply_r_larch_add_sub(struct module *mod, u32 *location, Elf_Addr v,
}
}

static int apply_r_larch_b26(struct module *mod, u32 *location, Elf_Addr v,
s64 *rela_stack, size_t *rela_stack_top, unsigned int type)
{
ptrdiff_t offset = (void *)v - (void *)location;

if (offset >= SZ_128M)
v = module_emit_plt_entry(mod, v);

if (offset < -SZ_128M)
v = module_emit_plt_entry(mod, v);

offset = (void *)v - (void *)location;

if (!signed_imm_check(offset, 28)) {
pr_err("module %s: jump offset = 0x%llx overflow! dangerous R_LARCH_B26 (%u) relocation\n",
mod->name, (long long)offset, type);
return -ENOEXEC;
}

if (offset & 3) {
pr_err("module %s: jump offset = 0x%llx unaligned! dangerous R_LARCH_B26 (%u) relocation\n",
mod->name, (long long)offset, type);
return -ENOEXEC;
}

*location &= ~(u32)0x3ffffff;
*location |= (offset >> 18) & 0x3ff;
*location |= ((offset >> 2) & 0xffff) << 10;
return 0;
}

static int apply_r_larch_pcala_hi20(struct module *mod, u32 *location,
Elf_Addr v, s64 *rela_stack, size_t *rela_stack_top,
unsigned int type)
{
ptrdiff_t offset = (void *)((v + 0x800) & ~0xfff) -
(void *)((Elf_Addr)location & ~0xfff);

if (!signed_imm_check(offset, 32)) {
pr_err("module %s: PCALA offset = 0x%llx does not fit in 32-bit signed and is unsupported by kernel! dangerous %s (%u) relocation\n",
mod->name, (long long)offset, __func__, type);
return -ENOEXEC;
}

*location &= ~((u32)0xfffff << 5);
*location |= ((offset >> 12) & 0xfffff) << 5;
return 0;
}

static int apply_r_larch_got_pc_hi20(struct module *mod, u32 *location,
Elf_Addr v, s64 *rela_stack, size_t *rela_stack_top,
unsigned int type)
{
Elf_Addr got = module_emit_got_entry(mod, v);

return apply_r_larch_pcala_hi20(mod, location, got, rela_stack,
rela_stack_top, type);
}

static int apply_r_larch_pcala_lo12(struct module *mod, u32 *location,
Elf_Addr v, s64 *rela_stack, size_t *rela_stack_top,
unsigned int type)
{
*location &= ~((u32)0xfff << 10);
*location |= ((u32)v & 0xfff) << 10;
return 0;
}

static int apply_r_larch_got_pc_lo12(struct module *mod, u32 *location,
Elf_Addr v, s64 *rela_stack, size_t *rela_stack_top,
unsigned int type)
{
Elf_Addr got = module_emit_got_entry(mod, v);

return apply_r_larch_pcala_lo12(mod, location, got, rela_stack,
rela_stack_top, type);
}

/*
* reloc_handlers_rela() - Apply a particular relocation to a module
* @mod: the module to apply the reloc to
Expand Down Expand Up @@ -321,6 +399,11 @@ static reloc_rela_handler reloc_rela_handlers[] = {
[R_LARCH_SOP_POP_32_S_10_5 ... R_LARCH_SOP_POP_32_U] = apply_r_larch_sop_imm_field,
[R_LARCH_ADD32 ... R_LARCH_SUB64] = apply_r_larch_add_sub,
[R_LARCH_SOP_PUSH_GPREL] = apply_r_larch_sop_push_gprel,
[R_LARCH_B26] = apply_r_larch_b26,
[R_LARCH_PCALA_HI20] = apply_r_larch_pcala_hi20,
[R_LARCH_PCALA_LO12] = apply_r_larch_pcala_lo12,
[R_LARCH_GOT_PC_HI20] = apply_r_larch_got_pc_hi20,
[R_LARCH_GOT_PC_LO12] = apply_r_larch_got_pc_lo12,
};

int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
Expand Down

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