RISC-V: Add section of GOT.PLT for kernel module

Separate the function symbol address from .plt to .got.plt section.

The original plt entry has trampoline code with symbol address,
there is a 32-bit padding bwtween jar instruction and symbol address.

Extract the symbol address to .got.plt to reduce the module size.

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

1 files changed, 19 insertions, 2 deletions

diff --git a/arch/riscv/kernel/module-sections.c b/arch/riscv/kernel/module-sections.c
index 94ba1551eac3..bbbd26e19bfd 100644
--- a/arch/riscv/kernel/module-sections.c
+++ b/arch/riscv/kernel/module-sections.c
@@ -30,18 +30,23 @@ u64 module_emit_got_entry(struct module *mod, u64 val)
 
 u64 module_emit_plt_entry(struct module *mod, u64 val)
 {
+        struct mod_section *got_plt_sec = &mod->arch.got_plt;
+        struct got_entry *got_plt;
         struct mod_section *plt_sec = &mod->arch.plt;
-        struct plt_entry *plt = get_plt_entry(val, plt_sec);
+        struct plt_entry *plt = get_plt_entry(val, plt_sec, got_plt_sec);
         int i = plt_sec->num_entries;
 
         if (plt)
                 return (u64)plt;
 
         /* There is no duplicate entry, create a new one */
+        got_plt = (struct got_entry *)got_plt_sec->shdr->sh_addr;
+        got_plt[i] = emit_got_entry(val);
         plt = (struct plt_entry *)plt_sec->shdr->sh_addr;
-        plt[i] = emit_plt_entry(val);
+        plt[i] = emit_plt_entry(val, (u64)&plt[i], (u64)&got_plt[i]);
 
         plt_sec->num_entries++;
+        got_plt_sec->num_entries++;
         BUG_ON(plt_sec->num_entries > plt_sec->max_entries);
 
         return (u64)&plt[i];
@@ -94,6 +99,8 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
                         mod->arch.plt.shdr = sechdrs + i;
                 else if (!strcmp(secstrings + sechdrs[i].sh_name, ".got"))
                         mod->arch.got.shdr = sechdrs + i;
+                else if (!strcmp(secstrings + sechdrs[i].sh_name, ".got.plt"))
+                        mod->arch.got_plt.shdr = sechdrs + i;
         }
 
         if (!mod->arch.plt.shdr) {
@@ -104,6 +111,10 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
                 pr_err("%s: module GOT section(s) missing\n", mod->name);
                 return -ENOEXEC;
         }
+        if (!mod->arch.got_plt.shdr) {
+                pr_err("%s: module GOT.PLT section(s) missing\n", mod->name);
+                return -ENOEXEC;
+        }
 
         /* Calculate the maxinum number of entries */
         for (i = 0; i < ehdr->e_shnum; i++) {
@@ -135,5 +146,11 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
         mod->arch.got.num_entries = 0;
         mod->arch.got.max_entries = num_gots;
 
+        mod->arch.got_plt.shdr->sh_type = SHT_NOBITS;
+        mod->arch.got_plt.shdr->sh_flags = SHF_ALLOC;
+        mod->arch.got_plt.shdr->sh_addralign = L1_CACHE_BYTES;
+        mod->arch.got_plt.shdr->sh_size = (num_plts + 1) * sizeof(struct got_entry);
+        mod->arch.got_plt.num_entries = 0;
+        mod->arch.got_plt.max_entries = num_plts;
         return 0;
 }