1 files changed, 213 insertions, 0 deletions
diff --git a/arch/riscv/kernel/module-sections.c b/arch/riscv/kernel/module-sections.c
new file mode 100644
index 000000000000..1675cbad8619
--- /dev/null
+++ b/arch/riscv/kernel/module-sections.c
@@ -0,0 +1,213 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright (C) 2014-2017 Linaro Ltd. <ard.biesheuvel@linaro.org>
+ *
+ * Copyright (C) 2018 Andes Technology Corporation <zong@andestech.com>
+ */
+
+#include <linux/elf.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleloader.h>
+#include <linux/sort.h>
+
+unsigned long module_emit_got_entry(struct module *mod, unsigned long val)
+{
+	struct mod_section *got_sec = &mod->arch.got;
+	int i = got_sec->num_entries;
+	struct got_entry *got = get_got_entry(val, got_sec);
+
+	if (got)
+		return (unsigned long)got;
+
+	/* There is no duplicate entry, create a new one */
+	got = (struct got_entry *)got_sec->shdr->sh_addr;
+	got[i] = emit_got_entry(val);
+
+	got_sec->num_entries++;
+	BUG_ON(got_sec->num_entries > got_sec->max_entries);
+
+	return (unsigned long)&got[i];
+}
+
+unsigned long module_emit_plt_entry(struct module *mod, unsigned long 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, got_plt_sec);
+	int i = plt_sec->num_entries;
+
+	if (plt)
+		return (unsigned long)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,
+				(unsigned long)&plt[i],
+				(unsigned long)&got_plt[i]);
+
+	plt_sec->num_entries++;
+	got_plt_sec->num_entries++;
+	BUG_ON(plt_sec->num_entries > plt_sec->max_entries);
+
+	return (unsigned long)&plt[i];
+}
+
+#define cmp_3way(a, b)	((a) < (b) ? -1 : (a) > (b))
+
+static int cmp_rela(const void *a, const void *b)
+{
+	const Elf_Rela *x = a, *y = b;
+	int i;
+
+	/* sort by type, symbol index and addend */
+	i = cmp_3way(x->r_info, y->r_info);
+	if (i == 0)
+		i = cmp_3way(x->r_addend, y->r_addend);
+	return i;
+}
+
+static bool duplicate_rela(const Elf_Rela *rela, int idx)
+{
+	/*
+	 * Entries are sorted by type, symbol index and addend. That means
+	 * that, if a duplicate entry exists, it must be in the preceding slot.
+	 */
+	return idx > 0 && cmp_rela(rela + idx, rela + idx - 1) == 0;
+}
+
+static void count_max_entries(const Elf_Rela *relas, size_t num,
+			      unsigned int *plts, unsigned int *gots)
+{
+	for (size_t i = 0; i < num; i++) {
+		if (duplicate_rela(relas, i))
+			continue;
+
+		switch (ELF_R_TYPE(relas[i].r_info)) {
+		case R_RISCV_CALL_PLT:
+		case R_RISCV_PLT32:
+			(*plts)++;
+			break;
+		case R_RISCV_GOT_HI20:
+			(*gots)++;
+			break;
+		default:
+			unreachable();
+		}
+	}
+}
+
+static bool rela_needs_plt_got_entry(const Elf_Rela *rela)
+{
+	switch (ELF_R_TYPE(rela->r_info)) {
+	case R_RISCV_CALL_PLT:
+	case R_RISCV_GOT_HI20:
+	case R_RISCV_PLT32:
+		return true;
+	default:
+		return false;
+	}
+}
+
+int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
+			      char *secstrings, struct module *mod)
+{
+	size_t num_scratch_relas = 0;
+	unsigned int num_plts = 0;
+	unsigned int num_gots = 0;
+	Elf_Rela *scratch = NULL;
+	Elf_Rela *new_scratch;
+	size_t scratch_size = 0;
+	int i;
+
+	/*
+	 * Find the empty .got and .plt sections.
+	 */
+	for (i = 0; i < ehdr->e_shnum; i++) {
+		if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt"))
+			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) {
+		pr_err("%s: module PLT section(s) missing\n", mod->name);
+		return -ENOEXEC;
+	}
+	if (!mod->arch.got.shdr) {
+		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++) {
+		size_t num_relas = sechdrs[i].sh_size / sizeof(Elf_Rela);
+		Elf_Rela *relas = (void *)ehdr + sechdrs[i].sh_offset;
+		Elf_Shdr *dst_sec = sechdrs + sechdrs[i].sh_info;
+		size_t scratch_size_needed;
+
+		if (sechdrs[i].sh_type != SHT_RELA)
+			continue;
+
+		/* ignore relocations that operate on non-exec sections */
+		if (!(dst_sec->sh_flags & SHF_EXECINSTR))
+			continue;
+
+		/*
+		 * apply_relocate_add() relies on HI20 and LO12 relocation pairs being
+		 * close together, so sort a copy of the section to avoid interfering.
+		 */
+		scratch_size_needed = (num_scratch_relas + num_relas) * sizeof(*scratch);
+		if (scratch_size_needed > scratch_size) {
+			scratch_size = scratch_size_needed;
+			new_scratch = kvrealloc(scratch, scratch_size, GFP_KERNEL);
+			if (!new_scratch) {
+				kvfree(scratch);
+				return -ENOMEM;
+			}
+			scratch = new_scratch;
+		}
+
+		for (size_t j = 0; j < num_relas; j++)
+			if (rela_needs_plt_got_entry(&relas[j]))
+				scratch[num_scratch_relas++] = relas[j];
+	}
+
+	if (scratch) {
+		/* sort the accumulated PLT/GOT relocations so duplicates are adjacent */
+		sort(scratch, num_scratch_relas, sizeof(*scratch), cmp_rela, NULL);
+		count_max_entries(scratch, num_scratch_relas, &num_plts, &num_gots);
+		kvfree(scratch);
+	}
+
+	mod->arch.plt.shdr->sh_type = SHT_NOBITS;
+	mod->arch.plt.shdr->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
+	mod->arch.plt.shdr->sh_addralign = L1_CACHE_BYTES;
+	mod->arch.plt.shdr->sh_size = (num_plts + 1) * sizeof(struct plt_entry);
+	mod->arch.plt.num_entries = 0;
+	mod->arch.plt.max_entries = num_plts;
+
+	mod->arch.got.shdr->sh_type = SHT_NOBITS;
+	mod->arch.got.shdr->sh_flags = SHF_ALLOC;
+	mod->arch.got.shdr->sh_addralign = L1_CACHE_BYTES;
+	mod->arch.got.shdr->sh_size = (num_gots + 1) * sizeof(struct got_entry);
+	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;
+}