Commit 35fa91ee authored by Ard Biesheuvel's avatar Ard Biesheuvel
Browse files

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: default avatarJongsung Kim <neidhard.kim@lge.com>
Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
parent 3eab887a

arch/arm/include/asm/module.h

+2 −4
Original line number Diff line number Diff line
@@ -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

};

arch/arm/kernel/module-plts.c

+22 −46
Original line number Diff line number Diff line
@@ -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,

	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.core_plt_count = 0;

	mod->arch.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);

	pr_debug("%s: plt=%x\n", __func__, mod->arch.plt->sh_size);

	return 0;

}

arch/arm/kernel/module.lds

+1 −2
Original line number Diff line number Diff line 
SECTIONS {

        .core.plt : { BYTE(0) }

        .init.plt : { BYTE(0) }

	.plt : { BYTE(0) }

}

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