RISC-V: Support GOT_HI20/CALL_PLT relocation type in kernel module

For CALL_PLT, emit the plt entry only when offset is more than 32-bit.

For PCREL_LO12, it uses the location of corresponding HI20 to
get the address of external symbol. It should check the HI20 type
is the PCREL_HI20 or GOT_HI20, because sometime the location will
have two or more relocation types.
For example:
0:   00000797                auipc   a5,0x0
                     0: R_RISCV_ALIGN        *ABS*
                     0: R_RISCV_GOT_HI20     SYMBOL
4:   0007b783                ld      a5,0(a5) # 0 <SYMBOL>
                     4: R_RISCV_PCREL_LO12_I .L0
                     4: R_RISCV_RELAX        *ABS*

Signed-off-by: Zong Li <zong@andestech.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

1 files changed, 52 insertions, 10 deletions

diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
index e0f05034fc21..be717bd7cea7 100644
--- a/arch/riscv/kernel/module.c
+++ b/arch/riscv/kernel/module.c
@@ -92,6 +92,28 @@ static int apply_r_riscv_pcrel_lo12_s_rela(struct module *me, u32 *location,
         return 0;
 }
 
+static int apply_r_riscv_got_hi20_rela(struct module *me, u32 *location,
+                                       Elf_Addr v)
+{
+        s64 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, 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)
 {
@@ -100,10 +122,16 @@ static int apply_r_riscv_call_plt_rela(struct module *me, u32 *location,
         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, v, location);
-                return -EINVAL;
+                /* 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, v, location);
+                        return -EINVAL;
+                }
         }
 
         hi20 = (offset + 0x800) & 0xfffff000;
@@ -127,6 +155,7 @@ static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
         [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_GOT_HI20]              = apply_r_riscv_got_hi20_rela,
         [R_RISCV_CALL_PLT]              = apply_r_riscv_call_plt_rela,
         [R_RISCV_RELAX]                 = apply_r_riscv_relax_rela,
 };
@@ -184,25 +213,38 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
                                 u64 hi20_loc =
                                         sechdrs[sechdrs[relsec].sh_info].sh_addr
                                         + rel[j].r_offset;
-                                /* Find the corresponding HI20 PC-relative relocation entry */
-                                if (hi20_loc == sym->st_value) {
+                                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);
                                         u64 hi20_sym_val =
                                                 hi20_sym->st_value
                                                 + rel[j].r_addend;
+
                                         /* Calculate lo12 */
-                                        s64 offset = hi20_sym_val - hi20_loc;
-                                        s32 hi20 = (offset + 0x800) & 0xfffff000;
-                                        s32 lo12 = offset - hi20;
+                                        u64 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 PC-relative relocation information\n",
+                                  "%s: Can not find HI20 relocation information\n",
                                   me->name);
                                 return -EINVAL;
                         }