ARM: kernel: merge core and init PLTs

The PLT code uses a separate .init.plt section to allocate PLT entries
for jump and call instructions in __init code. However, even for fairly
sizable modules like mac80211.ko, we only end up with a couple of PLT
entries in the .init section, and so we can simplify the code
significantly by emitting all PLT entries into the same section.

Tested-by: Jongsung Kim <neidhard.kim@lge.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

3 files changed, 25 insertions, 52 deletions

diff --git a/arch/arm/include/asm/module.h b/arch/arm/include/asm/module.h
index e358b7966c06..464748b9fd7d 100644
--- a/arch/arm/include/asm/module.h
+++ b/arch/arm/include/asm/module.h
@@ -23,10 +23,8 @@ struct mod_arch_specific {
         struct unwind_table *unwind[ARM_SEC_MAX];
 #endif
 #ifdef CONFIG_ARM_MODULE_PLTS
-        struct elf32_shdr   *core_plt;
-        struct elf32_shdr   *init_plt;
-        int                 core_plt_count;
-        int                 init_plt_count;
+        struct elf32_shdr   *plt;
+        int                 plt_count;
 #endif
 };
 
diff --git a/arch/arm/kernel/module-plts.c b/arch/arm/kernel/module-plts.c
index 0c7efc3446c0..6832d1d6444e 100644
--- a/arch/arm/kernel/module-plts.c
+++ b/arch/arm/kernel/module-plts.c
@@ -30,28 +30,16 @@ struct plt_entries {
         u32     lit[PLT_ENT_COUNT];
 };
 
-static bool in_init(const struct module *mod, u32 addr)
-{
-        return addr - (u32)mod->init_layout.base < mod->init_layout.size;
-}
-
 u32 get_module_plt(struct module *mod, unsigned long loc, Elf32_Addr val)
 {
         struct plt_entries *plt, *plt_end;
-        int c, *count;
-
-        if (in_init(mod, loc)) {
-                plt = (void *)mod->arch.init_plt->sh_addr;
-                plt_end = (void *)plt + mod->arch.init_plt->sh_size;
-                count = &mod->arch.init_plt_count;
-        } else {
-                plt = (void *)mod->arch.core_plt->sh_addr;
-                plt_end = (void *)plt + mod->arch.core_plt->sh_size;
-                count = &mod->arch.core_plt_count;
-        }
+        int c;
+
+        plt = (void *)mod->arch.plt->sh_addr;
+        plt_end = (void *)plt + mod->arch.plt->sh_size;
 
         /* Look for an existing entry pointing to 'val' */
-        for (c = *count; plt < plt_end; c -= PLT_ENT_COUNT, plt++) {
+        for (c = mod->arch.plt_count; plt < plt_end; c -= PLT_ENT_COUNT, plt++) {
                 int i;
 
                 if (!c) {
@@ -60,13 +48,13 @@ u32 get_module_plt(struct module *mod, unsigned long loc, Elf32_Addr val)
                                 { [0 ... PLT_ENT_COUNT - 1] = PLT_ENT_LDR, },
                                 { val, }
                         };
-                        ++*count;
+                        mod->arch.plt_count++;
                         return (u32)plt->ldr;
                 }
                 for (i = 0; i < PLT_ENT_COUNT; i++) {
                         if (!plt->lit[i]) {
                                 plt->lit[i] = val;
-                                ++*count;
+                                mod->arch.plt_count++;
                         }
                         if (plt->lit[i] == val)
                                 return (u32)&plt->ldr[i];
@@ -132,21 +120,19 @@ static unsigned int count_plts(Elf32_Addr base, const Elf32_Rel *rel, int num)
 int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
                               char *secstrings, struct module *mod)
 {
-        unsigned long core_plts = 0, init_plts = 0;
+        unsigned long plts = 0;
         Elf32_Shdr *s, *sechdrs_end = sechdrs + ehdr->e_shnum;
 
         /*
          * To store the PLTs, we expand the .text section for core module code
-         * and the .init.text section for initialization code.
+         * and for initialization code.
          */
         for (s = sechdrs; s < sechdrs_end; ++s)
-                if (strcmp(".core.plt", secstrings + s->sh_name) == 0)
-                        mod->arch.core_plt = s;
-                else if (strcmp(".init.plt", secstrings + s->sh_name) == 0)
-                        mod->arch.init_plt = s;
+                if (strcmp(".plt", secstrings + s->sh_name) == 0)
+                        mod->arch.plt = s;
 
-        if (!mod->arch.core_plt || !mod->arch.init_plt) {
-                pr_err("%s: sections missing\n", mod->name);
+        if (!mod->arch.plt) {
+                pr_err("%s: module PLT section missing\n", mod->name);
                 return -ENOEXEC;
         }
 
@@ -158,26 +144,16 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
                 if (s->sh_type != SHT_REL)
                         continue;
 
-                if (strstr(secstrings + s->sh_name, ".init"))
-                        init_plts += count_plts(dstsec->sh_addr, rels, numrels);
-                else
-                        core_plts += count_plts(dstsec->sh_addr, rels, numrels);
+                plts += count_plts(dstsec->sh_addr, rels, numrels);
         }
 
-        mod->arch.core_plt->sh_type = SHT_NOBITS;
-        mod->arch.core_plt->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
-        mod->arch.core_plt->sh_addralign = L1_CACHE_BYTES;
-        mod->arch.core_plt->sh_size = round_up(core_plts * PLT_ENT_SIZE,
-                                               sizeof(struct plt_entries));
-        mod->arch.core_plt_count = 0;
-
-        mod->arch.init_plt->sh_type = SHT_NOBITS;
-        mod->arch.init_plt->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
-        mod->arch.init_plt->sh_addralign = L1_CACHE_BYTES;
-        mod->arch.init_plt->sh_size = round_up(init_plts * PLT_ENT_SIZE,
-                                               sizeof(struct plt_entries));
-        mod->arch.init_plt_count = 0;
-        pr_debug("%s: core.plt=%x, init.plt=%x\n", __func__,
-                 mod->arch.core_plt->sh_size, mod->arch.init_plt->sh_size);
+        mod->arch.plt->sh_type = SHT_NOBITS;
+        mod->arch.plt->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
+        mod->arch.plt->sh_addralign = L1_CACHE_BYTES;
+        mod->arch.plt->sh_size = round_up(plts * PLT_ENT_SIZE,
+                                          sizeof(struct plt_entries));
+        mod->arch.plt_count = 0;
+
+        pr_debug("%s: plt=%x\n", __func__, mod->arch.plt->sh_size);
         return 0;
 }
diff --git a/arch/arm/kernel/module.lds b/arch/arm/kernel/module.lds
index 3682fa107918..05881e2b414c 100644
--- a/arch/arm/kernel/module.lds
+++ b/arch/arm/kernel/module.lds
@@ -1,4 +1,3 @@
 SECTIONS {
-        .core.plt : { BYTE(0) }
-        .init.plt : { BYTE(0) }
+        .plt : { BYTE(0) }
 }