v4.19.13 snapshot.
diff --git a/arch/arm/kernel/module-plts.c b/arch/arm/kernel/module-plts.c
new file mode 100644
index 0000000..3d0c2e4
--- /dev/null
+++ b/arch/arm/kernel/module-plts.c
@@ -0,0 +1,261 @@
+/*
+ * Copyright (C) 2014-2017 Linaro Ltd. <ard.biesheuvel@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/elf.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/sort.h>
+
+#include <asm/cache.h>
+#include <asm/opcodes.h>
+
+#define PLT_ENT_STRIDE L1_CACHE_BYTES
+#define PLT_ENT_COUNT (PLT_ENT_STRIDE / sizeof(u32))
+#define PLT_ENT_SIZE (sizeof(struct plt_entries) / PLT_ENT_COUNT)
+
+#ifdef CONFIG_THUMB2_KERNEL
+#define PLT_ENT_LDR __opcode_to_mem_thumb32(0xf8dff000 | \
+ (PLT_ENT_STRIDE - 4))
+#else
+#define PLT_ENT_LDR __opcode_to_mem_arm(0xe59ff000 | \
+ (PLT_ENT_STRIDE - 8))
+#endif
+
+struct plt_entries {
+ u32 ldr[PLT_ENT_COUNT];
+ u32 lit[PLT_ENT_COUNT];
+};
+
+static bool in_init(const struct module *mod, unsigned long loc)
+{
+ return loc - (u32)mod->init_layout.base < mod->init_layout.size;
+}
+
+u32 get_module_plt(struct module *mod, unsigned long loc, Elf32_Addr val)
+{
+ struct mod_plt_sec *pltsec = !in_init(mod, loc) ? &mod->arch.core :
+ &mod->arch.init;
+
+ struct plt_entries *plt = (struct plt_entries *)pltsec->plt->sh_addr;
+ int idx = 0;
+
+ /*
+ * Look for an existing entry pointing to 'val'. Given that the
+ * relocations are sorted, this will be the last entry we allocated.
+ * (if one exists).
+ */
+ if (pltsec->plt_count > 0) {
+ plt += (pltsec->plt_count - 1) / PLT_ENT_COUNT;
+ idx = (pltsec->plt_count - 1) % PLT_ENT_COUNT;
+
+ if (plt->lit[idx] == val)
+ return (u32)&plt->ldr[idx];
+
+ idx = (idx + 1) % PLT_ENT_COUNT;
+ if (!idx)
+ plt++;
+ }
+
+ pltsec->plt_count++;
+ BUG_ON(pltsec->plt_count * PLT_ENT_SIZE > pltsec->plt->sh_size);
+
+ if (!idx)
+ /* Populate a new set of entries */
+ *plt = (struct plt_entries){
+ { [0 ... PLT_ENT_COUNT - 1] = PLT_ENT_LDR, },
+ { val, }
+ };
+ else
+ plt->lit[idx] = val;
+
+ return (u32)&plt->ldr[idx];
+}
+
+#define cmp_3way(a,b) ((a) < (b) ? -1 : (a) > (b))
+
+static int cmp_rel(const void *a, const void *b)
+{
+ const Elf32_Rel *x = a, *y = b;
+ int i;
+
+ /* sort by type and symbol index */
+ i = cmp_3way(ELF32_R_TYPE(x->r_info), ELF32_R_TYPE(y->r_info));
+ if (i == 0)
+ i = cmp_3way(ELF32_R_SYM(x->r_info), ELF32_R_SYM(y->r_info));
+ return i;
+}
+
+static bool is_zero_addend_relocation(Elf32_Addr base, const Elf32_Rel *rel)
+{
+ u32 *tval = (u32 *)(base + rel->r_offset);
+
+ /*
+ * Do a bitwise compare on the raw addend rather than fully decoding
+ * the offset and doing an arithmetic comparison.
+ * Note that a zero-addend jump/call relocation is encoded taking the
+ * PC bias into account, i.e., -8 for ARM and -4 for Thumb2.
+ */
+ switch (ELF32_R_TYPE(rel->r_info)) {
+ u16 upper, lower;
+
+ case R_ARM_THM_CALL:
+ case R_ARM_THM_JUMP24:
+ upper = __mem_to_opcode_thumb16(((u16 *)tval)[0]);
+ lower = __mem_to_opcode_thumb16(((u16 *)tval)[1]);
+
+ return (upper & 0x7ff) == 0x7ff && (lower & 0x2fff) == 0x2ffe;
+
+ case R_ARM_CALL:
+ case R_ARM_PC24:
+ case R_ARM_JUMP24:
+ return (__mem_to_opcode_arm(*tval) & 0xffffff) == 0xfffffe;
+ }
+ BUG();
+}
+
+static bool duplicate_rel(Elf32_Addr base, const Elf32_Rel *rel, int num)
+{
+ const Elf32_Rel *prev;
+
+ /*
+ * Entries are sorted by type and symbol index. That means that,
+ * if a duplicate entry exists, it must be in the preceding
+ * slot.
+ */
+ if (!num)
+ return false;
+
+ prev = rel + num - 1;
+ return cmp_rel(rel + num, prev) == 0 &&
+ is_zero_addend_relocation(base, prev);
+}
+
+/* Count how many PLT entries we may need */
+static unsigned int count_plts(const Elf32_Sym *syms, Elf32_Addr base,
+ const Elf32_Rel *rel, int num, Elf32_Word dstidx)
+{
+ unsigned int ret = 0;
+ const Elf32_Sym *s;
+ int i;
+
+ for (i = 0; i < num; i++) {
+ switch (ELF32_R_TYPE(rel[i].r_info)) {
+ case R_ARM_CALL:
+ case R_ARM_PC24:
+ case R_ARM_JUMP24:
+ case R_ARM_THM_CALL:
+ case R_ARM_THM_JUMP24:
+ /*
+ * We only have to consider branch targets that resolve
+ * to symbols that are defined in a different section.
+ * This is not simply a heuristic, it is a fundamental
+ * limitation, since there is no guaranteed way to emit
+ * PLT entries sufficiently close to the branch if the
+ * section size exceeds the range of a branch
+ * instruction. So ignore relocations against defined
+ * symbols if they live in the same section as the
+ * relocation target.
+ */
+ s = syms + ELF32_R_SYM(rel[i].r_info);
+ if (s->st_shndx == dstidx)
+ break;
+
+ /*
+ * Jump relocations with non-zero addends against
+ * undefined symbols are supported by the ELF spec, but
+ * do not occur in practice (e.g., 'jump n bytes past
+ * the entry point of undefined function symbol f').
+ * So we need to support them, but there is no need to
+ * take them into consideration when trying to optimize
+ * this code. So let's only check for duplicates when
+ * the addend is zero. (Note that calls into the core
+ * module via init PLT entries could involve section
+ * relative symbol references with non-zero addends, for
+ * which we may end up emitting duplicates, but the init
+ * PLT is released along with the rest of the .init
+ * region as soon as module loading completes.)
+ */
+ if (!is_zero_addend_relocation(base, rel + i) ||
+ !duplicate_rel(base, rel, i))
+ ret++;
+ }
+ }
+ return ret;
+}
+
+int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
+ char *secstrings, struct module *mod)
+{
+ unsigned long core_plts = 0;
+ unsigned long init_plts = 0;
+ Elf32_Shdr *s, *sechdrs_end = sechdrs + ehdr->e_shnum;
+ Elf32_Sym *syms = NULL;
+
+ /*
+ * To store the PLTs, we expand the .text section for core module code
+ * and for initialization code.
+ */
+ for (s = sechdrs; s < sechdrs_end; ++s) {
+ if (strcmp(".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;
+ else if (s->sh_type == SHT_SYMTAB)
+ syms = (Elf32_Sym *)s->sh_addr;
+ }
+
+ if (!mod->arch.core.plt || !mod->arch.init.plt) {
+ pr_err("%s: module PLT section(s) missing\n", mod->name);
+ return -ENOEXEC;
+ }
+ if (!syms) {
+ pr_err("%s: module symtab section missing\n", mod->name);
+ return -ENOEXEC;
+ }
+
+ for (s = sechdrs + 1; s < sechdrs_end; ++s) {
+ Elf32_Rel *rels = (void *)ehdr + s->sh_offset;
+ int numrels = s->sh_size / sizeof(Elf32_Rel);
+ Elf32_Shdr *dstsec = sechdrs + s->sh_info;
+
+ if (s->sh_type != SHT_REL)
+ continue;
+
+ /* ignore relocations that operate on non-exec sections */
+ if (!(dstsec->sh_flags & SHF_EXECINSTR))
+ continue;
+
+ /* sort by type and symbol index */
+ sort(rels, numrels, sizeof(Elf32_Rel), cmp_rel, NULL);
+
+ if (strncmp(secstrings + dstsec->sh_name, ".init", 5) != 0)
+ core_plts += count_plts(syms, dstsec->sh_addr, rels,
+ numrels, s->sh_info);
+ else
+ init_plts += count_plts(syms, dstsec->sh_addr, rels,
+ numrels, s->sh_info);
+ }
+
+ 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: plt=%x, init.plt=%x\n", __func__,
+ mod->arch.core.plt->sh_size, mod->arch.init.plt->sh_size);
+ return 0;
+}