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Subject[RFC PATCH 5/5] livepatch: arm64: support relocation in a module
Date
From: Xie XiuQi <xiexiuqi@huawei.com>

This patch implement klp_write_module_reloc on arm64 platform.

Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Li Bin <huawei.libin@huawei.com>
---
arch/arm64/kernel/livepatch.c | 7 +-
arch/arm64/kernel/module.c | 355 +++++++++++++++++++++--------------------
2 files changed, 186 insertions(+), 176 deletions(-)

diff --git a/arch/arm64/kernel/livepatch.c b/arch/arm64/kernel/livepatch.c
index 2a55532..ad674f0 100644
--- a/arch/arm64/kernel/livepatch.c
+++ b/arch/arm64/kernel/livepatch.c
@@ -18,8 +18,11 @@
*/

#include <linux/module.h>
+#include <linux/uaccess.h>
#include <asm/livepatch.h>

+extern int static_relocate(struct module *mod, unsigned long type,
+ void * loc, unsigned long value);
/**
* klp_write_module_reloc() - write a relocation in a module
* @mod: module in which the section to be modified is found
@@ -33,6 +36,6 @@
int klp_write_module_reloc(struct module *mod, unsigned long type,
unsigned long loc, unsigned long value)
{
- pr_err("lpc_write_module_reloc has not supported now\n");
- return -ENOSYS;
+ /* Perform the static relocation. */
+ return static_relocate(mod, type, (void *)loc, value);
}
diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c
index 67bf410..7781241 100644
--- a/arch/arm64/kernel/module.c
+++ b/arch/arm64/kernel/module.c
@@ -193,6 +193,182 @@ static int reloc_insn_imm(enum aarch64_reloc_op op, void *place, u64 val,
return 0;
}

+int static_relocate(struct module *me, unsigned long type, void *loc,
+ unsigned long val)
+{
+ int ovf = 0;
+ bool overflow_check = true;
+ /* Perform the static relocation. */
+ switch (type) {
+ /* Null relocations. */
+ case R_ARM_NONE:
+ case R_AARCH64_NONE:
+ ovf = 0;
+ break;
+
+ /* Data relocations. */
+ case R_AARCH64_ABS64:
+ overflow_check = false;
+ ovf = reloc_data(RELOC_OP_ABS, loc, val, 64);
+ break;
+ case R_AARCH64_ABS32:
+ ovf = reloc_data(RELOC_OP_ABS, loc, val, 32);
+ break;
+ case R_AARCH64_ABS16:
+ ovf = reloc_data(RELOC_OP_ABS, loc, val, 16);
+ break;
+ case R_AARCH64_PREL64:
+ overflow_check = false;
+ ovf = reloc_data(RELOC_OP_PREL, loc, val, 64);
+ break;
+ case R_AARCH64_PREL32:
+ ovf = reloc_data(RELOC_OP_PREL, loc, val, 32);
+ break;
+ case R_AARCH64_PREL16:
+ ovf = reloc_data(RELOC_OP_PREL, loc, val, 16);
+ break;
+
+ /* MOVW instruction relocations. */
+ case R_AARCH64_MOVW_UABS_G0_NC:
+ overflow_check = false;
+ case R_AARCH64_MOVW_UABS_G0:
+ ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 0,
+ AARCH64_INSN_IMM_16);
+ break;
+ case R_AARCH64_MOVW_UABS_G1_NC:
+ overflow_check = false;
+ case R_AARCH64_MOVW_UABS_G1:
+ ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 16,
+ AARCH64_INSN_IMM_16);
+ break;
+ case R_AARCH64_MOVW_UABS_G2_NC:
+ overflow_check = false;
+ case R_AARCH64_MOVW_UABS_G2:
+ ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 32,
+ AARCH64_INSN_IMM_16);
+ break;
+ case R_AARCH64_MOVW_UABS_G3:
+ /* We're using the top bits so we can't overflow. */
+ overflow_check = false;
+ ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 48,
+ AARCH64_INSN_IMM_16);
+ break;
+ case R_AARCH64_MOVW_SABS_G0:
+ ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 0,
+ AARCH64_INSN_IMM_MOVNZ);
+ break;
+ case R_AARCH64_MOVW_SABS_G1:
+ ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 16,
+ AARCH64_INSN_IMM_MOVNZ);
+ break;
+ case R_AARCH64_MOVW_SABS_G2:
+ ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 32,
+ AARCH64_INSN_IMM_MOVNZ);
+ break;
+ case R_AARCH64_MOVW_PREL_G0_NC:
+ overflow_check = false;
+ ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 0,
+ AARCH64_INSN_IMM_MOVK);
+ break;
+ case R_AARCH64_MOVW_PREL_G0:
+ ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 0,
+ AARCH64_INSN_IMM_MOVNZ);
+ break;
+ case R_AARCH64_MOVW_PREL_G1_NC:
+ overflow_check = false;
+ ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 16,
+ AARCH64_INSN_IMM_MOVK);
+ break;
+ case R_AARCH64_MOVW_PREL_G1:
+ ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 16,
+ AARCH64_INSN_IMM_MOVNZ);
+ break;
+ case R_AARCH64_MOVW_PREL_G2_NC:
+ overflow_check = false;
+ ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 32,
+ AARCH64_INSN_IMM_MOVK);
+ break;
+ case R_AARCH64_MOVW_PREL_G2:
+ ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 32,
+ AARCH64_INSN_IMM_MOVNZ);
+ break;
+ case R_AARCH64_MOVW_PREL_G3:
+ /* We're using the top bits so we can't overflow. */
+ overflow_check = false;
+ ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 48,
+ AARCH64_INSN_IMM_MOVNZ);
+ break;
+
+ /* Immediate instruction relocations. */
+ case R_AARCH64_LD_PREL_LO19:
+ ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 2, 19,
+ AARCH64_INSN_IMM_19);
+ break;
+ case R_AARCH64_ADR_PREL_LO21:
+ ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 0, 21,
+ AARCH64_INSN_IMM_ADR);
+ break;
+ case R_AARCH64_ADR_PREL_PG_HI21_NC:
+ overflow_check = false;
+ case R_AARCH64_ADR_PREL_PG_HI21:
+ ovf = reloc_insn_imm(RELOC_OP_PAGE, loc, val, 12, 21,
+ AARCH64_INSN_IMM_ADR);
+ break;
+ case R_AARCH64_ADD_ABS_LO12_NC:
+ case R_AARCH64_LDST8_ABS_LO12_NC:
+ overflow_check = false;
+ ovf = reloc_insn_imm(RELOC_OP_ABS, loc, val, 0, 12,
+ AARCH64_INSN_IMM_12);
+ break;
+ case R_AARCH64_LDST16_ABS_LO12_NC:
+ overflow_check = false;
+ ovf = reloc_insn_imm(RELOC_OP_ABS, loc, val, 1, 11,
+ AARCH64_INSN_IMM_12);
+ break;
+ case R_AARCH64_LDST32_ABS_LO12_NC:
+ overflow_check = false;
+ ovf = reloc_insn_imm(RELOC_OP_ABS, loc, val, 2, 10,
+ AARCH64_INSN_IMM_12);
+ break;
+ case R_AARCH64_LDST64_ABS_LO12_NC:
+ overflow_check = false;
+ ovf = reloc_insn_imm(RELOC_OP_ABS, loc, val, 3, 9,
+ AARCH64_INSN_IMM_12);
+ break;
+ case R_AARCH64_LDST128_ABS_LO12_NC:
+ overflow_check = false;
+ ovf = reloc_insn_imm(RELOC_OP_ABS, loc, val, 4, 8,
+ AARCH64_INSN_IMM_12);
+ break;
+ case R_AARCH64_TSTBR14:
+ ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 2, 14,
+ AARCH64_INSN_IMM_14);
+ break;
+ case R_AARCH64_CONDBR19:
+ ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 2, 19,
+ AARCH64_INSN_IMM_19);
+ break;
+ case R_AARCH64_JUMP26:
+ case R_AARCH64_CALL26:
+ ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 2, 26,
+ AARCH64_INSN_IMM_26);
+ break;
+
+ default:
+ pr_err("module %s: unsupported RELA relocation: %lu\n",
+ me->name, type);
+ return -ENOEXEC;
+ }
+
+ if (overflow_check && ovf == -ERANGE) {
+ pr_err("module %s: overflow in relocation type %lu val %lx\n",
+ me->name, type, val);
+ return -ENOEXEC;
+ }
+
+ return 0;
+}
+
int apply_relocate_add(Elf64_Shdr *sechdrs,
const char *strtab,
unsigned int symindex,
@@ -200,12 +376,11 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
struct module *me)
{
unsigned int i;
- int ovf;
- bool overflow_check;
Elf64_Sym *sym;
void *loc;
u64 val;
Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
+ int type, ret;

for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
/* loc corresponds to P in the AArch64 ELF document. */
@@ -219,182 +394,14 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
/* val corresponds to (S + A) in the AArch64 ELF document. */
val = sym->st_value + rel[i].r_addend;

+ type = ELF64_R_TYPE(rel[i].r_info);
/* Check for overflow by default. */
- overflow_check = true;
-
- /* Perform the static relocation. */
- switch (ELF64_R_TYPE(rel[i].r_info)) {
- /* Null relocations. */
- case R_ARM_NONE:
- case R_AARCH64_NONE:
- ovf = 0;
- break;
-
- /* Data relocations. */
- case R_AARCH64_ABS64:
- overflow_check = false;
- ovf = reloc_data(RELOC_OP_ABS, loc, val, 64);
- break;
- case R_AARCH64_ABS32:
- ovf = reloc_data(RELOC_OP_ABS, loc, val, 32);
- break;
- case R_AARCH64_ABS16:
- ovf = reloc_data(RELOC_OP_ABS, loc, val, 16);
- break;
- case R_AARCH64_PREL64:
- overflow_check = false;
- ovf = reloc_data(RELOC_OP_PREL, loc, val, 64);
- break;
- case R_AARCH64_PREL32:
- ovf = reloc_data(RELOC_OP_PREL, loc, val, 32);
- break;
- case R_AARCH64_PREL16:
- ovf = reloc_data(RELOC_OP_PREL, loc, val, 16);
- break;
-
- /* MOVW instruction relocations. */
- case R_AARCH64_MOVW_UABS_G0_NC:
- overflow_check = false;
- case R_AARCH64_MOVW_UABS_G0:
- ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 0,
- AARCH64_INSN_IMM_16);
- break;
- case R_AARCH64_MOVW_UABS_G1_NC:
- overflow_check = false;
- case R_AARCH64_MOVW_UABS_G1:
- ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 16,
- AARCH64_INSN_IMM_16);
- break;
- case R_AARCH64_MOVW_UABS_G2_NC:
- overflow_check = false;
- case R_AARCH64_MOVW_UABS_G2:
- ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 32,
- AARCH64_INSN_IMM_16);
- break;
- case R_AARCH64_MOVW_UABS_G3:
- /* We're using the top bits so we can't overflow. */
- overflow_check = false;
- ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 48,
- AARCH64_INSN_IMM_16);
- break;
- case R_AARCH64_MOVW_SABS_G0:
- ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 0,
- AARCH64_INSN_IMM_MOVNZ);
- break;
- case R_AARCH64_MOVW_SABS_G1:
- ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 16,
- AARCH64_INSN_IMM_MOVNZ);
- break;
- case R_AARCH64_MOVW_SABS_G2:
- ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 32,
- AARCH64_INSN_IMM_MOVNZ);
- break;
- case R_AARCH64_MOVW_PREL_G0_NC:
- overflow_check = false;
- ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 0,
- AARCH64_INSN_IMM_MOVK);
- break;
- case R_AARCH64_MOVW_PREL_G0:
- ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 0,
- AARCH64_INSN_IMM_MOVNZ);
- break;
- case R_AARCH64_MOVW_PREL_G1_NC:
- overflow_check = false;
- ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 16,
- AARCH64_INSN_IMM_MOVK);
- break;
- case R_AARCH64_MOVW_PREL_G1:
- ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 16,
- AARCH64_INSN_IMM_MOVNZ);
- break;
- case R_AARCH64_MOVW_PREL_G2_NC:
- overflow_check = false;
- ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 32,
- AARCH64_INSN_IMM_MOVK);
- break;
- case R_AARCH64_MOVW_PREL_G2:
- ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 32,
- AARCH64_INSN_IMM_MOVNZ);
- break;
- case R_AARCH64_MOVW_PREL_G3:
- /* We're using the top bits so we can't overflow. */
- overflow_check = false;
- ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 48,
- AARCH64_INSN_IMM_MOVNZ);
- break;
-
- /* Immediate instruction relocations. */
- case R_AARCH64_LD_PREL_LO19:
- ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 2, 19,
- AARCH64_INSN_IMM_19);
- break;
- case R_AARCH64_ADR_PREL_LO21:
- ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 0, 21,
- AARCH64_INSN_IMM_ADR);
- break;
- case R_AARCH64_ADR_PREL_PG_HI21_NC:
- overflow_check = false;
- case R_AARCH64_ADR_PREL_PG_HI21:
- ovf = reloc_insn_imm(RELOC_OP_PAGE, loc, val, 12, 21,
- AARCH64_INSN_IMM_ADR);
- break;
- case R_AARCH64_ADD_ABS_LO12_NC:
- case R_AARCH64_LDST8_ABS_LO12_NC:
- overflow_check = false;
- ovf = reloc_insn_imm(RELOC_OP_ABS, loc, val, 0, 12,
- AARCH64_INSN_IMM_12);
- break;
- case R_AARCH64_LDST16_ABS_LO12_NC:
- overflow_check = false;
- ovf = reloc_insn_imm(RELOC_OP_ABS, loc, val, 1, 11,
- AARCH64_INSN_IMM_12);
- break;
- case R_AARCH64_LDST32_ABS_LO12_NC:
- overflow_check = false;
- ovf = reloc_insn_imm(RELOC_OP_ABS, loc, val, 2, 10,
- AARCH64_INSN_IMM_12);
- break;
- case R_AARCH64_LDST64_ABS_LO12_NC:
- overflow_check = false;
- ovf = reloc_insn_imm(RELOC_OP_ABS, loc, val, 3, 9,
- AARCH64_INSN_IMM_12);
- break;
- case R_AARCH64_LDST128_ABS_LO12_NC:
- overflow_check = false;
- ovf = reloc_insn_imm(RELOC_OP_ABS, loc, val, 4, 8,
- AARCH64_INSN_IMM_12);
- break;
- case R_AARCH64_TSTBR14:
- ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 2, 14,
- AARCH64_INSN_IMM_14);
- break;
- case R_AARCH64_CONDBR19:
- ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 2, 19,
- AARCH64_INSN_IMM_19);
- break;
- case R_AARCH64_JUMP26:
- case R_AARCH64_CALL26:
- ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 2, 26,
- AARCH64_INSN_IMM_26);
- break;
-
- default:
- pr_err("module %s: unsupported RELA relocation: %llu\n",
- me->name, ELF64_R_TYPE(rel[i].r_info));
- return -ENOEXEC;
- }
-
- if (overflow_check && ovf == -ERANGE)
- goto overflow;
-
+ ret = static_relocate(me, type, loc, val);
+ if (ret)
+ return ret;
}

return 0;
-
-overflow:
- pr_err("module %s: overflow in relocation type %d val %Lx\n",
- me->name, (int)ELF64_R_TYPE(rel[i].r_info), val);
- return -ENOEXEC;
}

int module_finalize(const Elf_Ehdr *hdr,
--
1.7.1


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