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 <[email protected]>
---
arch/loongarch/include/asm/elf.h | 37 +++++++++++
arch/loongarch/kernel/module-sections.c | 12 +++-
arch/loongarch/kernel/module.c | 83 +++++++++++++++++++++++++
3 files changed, 130 insertions(+), 2 deletions(-)
diff --git a/arch/loongarch/include/asm/elf.h b/arch/loongarch/include/asm/elf.h
index 5f3ff4781fda..7af0cebf28d7 100644
--- a/arch/loongarch/include/asm/elf.h
+++ b/arch/loongarch/include/asm/elf.h
@@ -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
diff --git a/arch/loongarch/kernel/module-sections.c b/arch/loongarch/kernel/module-sections.c
index 36a77771d18c..8c0e4ad048cc 100644
--- a/arch/loongarch/kernel/module-sections.c
+++ b/arch/loongarch/kernel/module-sections.c
@@ -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. */
+ }
}
}
diff --git a/arch/loongarch/kernel/module.c b/arch/loongarch/kernel/module.c
index 3ac4fbb5f109..8954ac24d4ab 100644
--- a/arch/loongarch/kernel/module.c
+++ b/arch/loongarch/kernel/module.c
@@ -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
@@ -321,6 +399,11 @@ static reloc_rela_handler reloc_rela_handlers[] = {
[R_LARCH_SOP_SUB ... R_LARCH_SOP_IF_ELSE] = apply_r_larch_sop,
[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_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,
--
2.37.0
On 07/28/2022 08:04 PM, Xi Ruoyao wrote:
> 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 <[email protected]>
> ---
> arch/loongarch/include/asm/elf.h | 37 +++++++++++
> arch/loongarch/kernel/module-sections.c | 12 +++-
> arch/loongarch/kernel/module.c | 83 +++++++++++++++++++++++++
> 3 files changed, 130 insertions(+), 2 deletions(-)
>
> diff --git a/arch/loongarch/include/asm/elf.h b/arch/loongarch/include/asm/elf.h
> index 5f3ff4781fda..7af0cebf28d7 100644
> --- a/arch/loongarch/include/asm/elf.h
> +++ b/arch/loongarch/include/asm/elf.h
> @@ -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
>
> diff --git a/arch/loongarch/kernel/module-sections.c b/arch/loongarch/kernel/module-sections.c
> index 36a77771d18c..8c0e4ad048cc 100644
> --- a/arch/loongarch/kernel/module-sections.c
> +++ b/arch/loongarch/kernel/module-sections.c
> @@ -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. */
> + }
> }
> }
>
> diff --git a/arch/loongarch/kernel/module.c b/arch/loongarch/kernel/module.c
> index 3ac4fbb5f109..8954ac24d4ab 100644
> --- a/arch/loongarch/kernel/module.c
> +++ b/arch/loongarch/kernel/module.c
> @@ -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;
> + }
Unaligned is handled more efficiently before overflow checking, while
being consistent with apply_r_larch_sop_imm_field.
> +
> + *location &= ~(u32)0x3ffffff;
> + *location |= (offset >> 18) & 0x3ff;
> + *location |= ((offset >> 2) & 0xffff) << 10;
It may be better to use the loongarch_instruction format to modify the
immediate field of the instruction, similar to the following:
union loongarch_instruction *insn = (union loongarch_instruction *)location;
offset >>= 2;
insn->reg0i26_format.immediate_l = offset & 0xffff;
insn->reg0i26_format.immediate_h = (offset >> 16) & 0x3ff;
> + 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;
Ditto.
> + 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;
Ditto.
Thanks,
Youling
> + 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
> @@ -321,6 +399,11 @@ static reloc_rela_handler reloc_rela_handlers[] = {
> [R_LARCH_SOP_SUB ... R_LARCH_SOP_IF_ELSE] = apply_r_larch_sop,
> [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_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,
>
On Thu, 2022-07-28 at 20:41 +0800, Youling Tang wrote:
> Unaligned is handled more efficiently before overflow checking, while
> being consistent with apply_r_larch_sop_imm_field.
Will move unaligned before overflow in V3.
> > +
> > + *location &= ~(u32)0x3ffffff;
> > + *location |= (offset >> 18) & 0x3ff;
> > + *location |= ((offset >> 2) & 0xffff) << 10;
>
> It may be better to use the loongarch_instruction format to modify the
> immediate field of the instruction, similar to the following:
>
> union loongarch_instruction *insn = (union loongarch_instruction *)location;
>
> offset >>= 2;
> insn->reg0i26_format.immediate_l = offset & 0xffff;
> insn->reg0i26_format.immediate_h = (offset >> 16) & 0x3ff;
Will use union loongarch_instruction in V3. Why didn't I notice it
before? :(
Thanks for the review!
--
Xi Ruoyao <[email protected]>
School of Aerospace Science and Technology, Xidian University