1 files changed, 340 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/module_32.c b/arch/powerpc/kernel/module_32.c
new file mode 100644
index 0000000000..816a63fd71
--- /dev/null
+++ b/arch/powerpc/kernel/module_32.c
@@ -0,0 +1,340 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*  Kernel module help for PPC.
+    Copyright (C) 2001 Rusty Russell.
+
+*/
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/moduleloader.h>
+#include <linux/elf.h>
+#include <linux/vmalloc.h>
+#include <linux/fs.h>
+#include <linux/string.h>
+#include <linux/kernel.h>
+#include <linux/ftrace.h>
+#include <linux/cache.h>
+#include <linux/bug.h>
+#include <linux/sort.h>
+#include <asm/setup.h>
+#include <asm/code-patching.h>
+
+/* Count how many different relocations (different symbol, different
+   addend) */
+static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num)
+{
+	unsigned int i, r_info, r_addend, _count_relocs;
+
+	_count_relocs = 0;
+	r_info = 0;
+	r_addend = 0;
+	for (i = 0; i < num; i++)
+		/* Only count 24-bit relocs, others don't need stubs */
+		if (ELF32_R_TYPE(rela[i].r_info) == R_PPC_REL24 &&
+		    (r_info != ELF32_R_SYM(rela[i].r_info) ||
+		     r_addend != rela[i].r_addend)) {
+			_count_relocs++;
+			r_info = ELF32_R_SYM(rela[i].r_info);
+			r_addend = rela[i].r_addend;
+		}
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+	_count_relocs++;	/* add one for ftrace_caller */
+#endif
+	return _count_relocs;
+}
+
+static int relacmp(const void *_x, const void *_y)
+{
+	const Elf32_Rela *x, *y;
+
+	y = (Elf32_Rela *)_x;
+	x = (Elf32_Rela *)_y;
+
+	/* Compare the entire r_info (as opposed to ELF32_R_SYM(r_info) only) to
+	 * make the comparison cheaper/faster. It won't affect the sorting or
+	 * the counting algorithms' performance
+	 */
+	if (x->r_info < y->r_info)
+		return -1;
+	else if (x->r_info > y->r_info)
+		return 1;
+	else if (x->r_addend < y->r_addend)
+		return -1;
+	else if (x->r_addend > y->r_addend)
+		return 1;
+	else
+		return 0;
+}
+
+/* Get the potential trampolines size required of the init and
+   non-init sections */
+static unsigned long get_plt_size(const Elf32_Ehdr *hdr,
+				  const Elf32_Shdr *sechdrs,
+				  const char *secstrings,
+				  int is_init)
+{
+	unsigned long ret = 0;
+	unsigned i;
+
+	/* Everything marked ALLOC (this includes the exported
+           symbols) */
+	for (i = 1; i < hdr->e_shnum; i++) {
+		/* If it's called *.init*, and we're not init, we're
+                   not interested */
+		if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != NULL)
+		    != is_init)
+			continue;
+
+		/* We don't want to look at debug sections. */
+		if (strstr(secstrings + sechdrs[i].sh_name, ".debug"))
+			continue;
+
+		if (sechdrs[i].sh_type == SHT_RELA) {
+			pr_debug("Found relocations in section %u\n", i);
+			pr_debug("Ptr: %p.  Number: %u\n",
+			       (void *)hdr + sechdrs[i].sh_offset,
+			       sechdrs[i].sh_size / sizeof(Elf32_Rela));
+
+			/* Sort the relocation information based on a symbol and
+			 * addend key. This is a stable O(n*log n) complexity
+			 * algorithm but it will reduce the complexity of
+			 * count_relocs() to linear complexity O(n)
+			 */
+			sort((void *)hdr + sechdrs[i].sh_offset,
+			     sechdrs[i].sh_size / sizeof(Elf32_Rela),
+			     sizeof(Elf32_Rela), relacmp, NULL);
+
+			ret += count_relocs((void *)hdr
+					     + sechdrs[i].sh_offset,
+					     sechdrs[i].sh_size
+					     / sizeof(Elf32_Rela))
+				* sizeof(struct ppc_plt_entry);
+		}
+	}
+
+	return ret;
+}
+
+int module_frob_arch_sections(Elf32_Ehdr *hdr,
+			      Elf32_Shdr *sechdrs,
+			      char *secstrings,
+			      struct module *me)
+{
+	unsigned int i;
+
+	/* Find .plt and .init.plt sections */
+	for (i = 0; i < hdr->e_shnum; i++) {
+		if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0)
+			me->arch.init_plt_section = i;
+		else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0)
+			me->arch.core_plt_section = i;
+	}
+	if (!me->arch.core_plt_section || !me->arch.init_plt_section) {
+		pr_err("Module doesn't contain .plt or .init.plt sections.\n");
+		return -ENOEXEC;
+	}
+
+	/* Override their sizes */
+	sechdrs[me->arch.core_plt_section].sh_size
+		= get_plt_size(hdr, sechdrs, secstrings, 0);
+	sechdrs[me->arch.init_plt_section].sh_size
+		= get_plt_size(hdr, sechdrs, secstrings, 1);
+	return 0;
+}
+
+static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val)
+{
+	if (entry->jump[0] != PPC_RAW_LIS(_R12, PPC_HA(val)))
+		return 0;
+	if (entry->jump[1] != PPC_RAW_ADDI(_R12, _R12, PPC_LO(val)))
+		return 0;
+	return 1;
+}
+
+/* Set up a trampoline in the PLT to bounce us to the distant function */
+static uint32_t do_plt_call(void *location,
+			    Elf32_Addr val,
+			    const Elf32_Shdr *sechdrs,
+			    struct module *mod)
+{
+	struct ppc_plt_entry *entry;
+
+	pr_debug("Doing plt for call to 0x%x at 0x%x\n", val, (unsigned int)location);
+	/* Init, or core PLT? */
+	if (within_module_core((unsigned long)location, mod))
+		entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr;
+	else
+		entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr;
+
+	/* Find this entry, or if that fails, the next avail. entry */
+	while (entry->jump[0]) {
+		if (entry_matches(entry, val)) return (uint32_t)entry;
+		entry++;
+	}
+
+	if (patch_instruction(&entry->jump[0], ppc_inst(PPC_RAW_LIS(_R12, PPC_HA(val)))))
+		return 0;
+	if (patch_instruction(&entry->jump[1], ppc_inst(PPC_RAW_ADDI(_R12, _R12, PPC_LO(val)))))
+		return 0;
+	if (patch_instruction(&entry->jump[2], ppc_inst(PPC_RAW_MTCTR(_R12))))
+		return 0;
+	if (patch_instruction(&entry->jump[3], ppc_inst(PPC_RAW_BCTR())))
+		return 0;
+
+	pr_debug("Initialized plt for 0x%x at %p\n", val, entry);
+	return (uint32_t)entry;
+}
+
+static int patch_location_16(uint32_t *loc, u16 value)
+{
+	loc = PTR_ALIGN_DOWN(loc, sizeof(u32));
+	return patch_instruction(loc, ppc_inst((*loc & 0xffff0000) | value));
+}
+
+int apply_relocate_add(Elf32_Shdr *sechdrs,
+		       const char *strtab,
+		       unsigned int symindex,
+		       unsigned int relsec,
+		       struct module *module)
+{
+	unsigned int i;
+	Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr;
+	Elf32_Sym *sym;
+	uint32_t *location;
+	uint32_t value;
+
+	pr_debug("Applying ADD relocate section %u to %u\n", relsec,
+	       sechdrs[relsec].sh_info);
+	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
+		/* This is where to make the change */
+		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
+			+ rela[i].r_offset;
+		/* This is the symbol it is referring to.  Note that all
+		   undefined symbols have been resolved.  */
+		sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
+			+ ELF32_R_SYM(rela[i].r_info);
+		/* `Everything is relative'. */
+		value = sym->st_value + rela[i].r_addend;
+
+		switch (ELF32_R_TYPE(rela[i].r_info)) {
+		case R_PPC_ADDR32:
+			/* Simply set it */
+			*(uint32_t *)location = value;
+			break;
+
+		case R_PPC_ADDR16_LO:
+			/* Low half of the symbol */
+			if (patch_location_16(location, PPC_LO(value)))
+				return -EFAULT;
+			break;
+
+		case R_PPC_ADDR16_HI:
+			/* Higher half of the symbol */
+			if (patch_location_16(location, PPC_HI(value)))
+				return -EFAULT;
+			break;
+
+		case R_PPC_ADDR16_HA:
+			if (patch_location_16(location, PPC_HA(value)))
+				return -EFAULT;
+			break;
+
+		case R_PPC_REL24:
+			if ((int)(value - (uint32_t)location) < -0x02000000
+			    || (int)(value - (uint32_t)location) >= 0x02000000) {
+				value = do_plt_call(location, value,
+						    sechdrs, module);
+				if (!value)
+					return -EFAULT;
+			}
+
+			/* Only replace bits 2 through 26 */
+			pr_debug("REL24 value = %08X. location = %08X\n",
+			       value, (uint32_t)location);
+			pr_debug("Location before: %08X.\n",
+			       *(uint32_t *)location);
+			value = (*(uint32_t *)location & ~PPC_LI_MASK) |
+				PPC_LI(value - (uint32_t)location);
+
+			if (patch_instruction(location, ppc_inst(value)))
+				return -EFAULT;
+
+			pr_debug("Location after: %08X.\n",
+			       *(uint32_t *)location);
+			pr_debug("ie. jump to %08X+%08X = %08X\n",
+				 *(uint32_t *)PPC_LI((uint32_t)location), (uint32_t)location,
+				 (*(uint32_t *)PPC_LI((uint32_t)location)) + (uint32_t)location);
+			break;
+
+		case R_PPC_REL32:
+			/* 32-bit relative jump. */
+			*(uint32_t *)location = value - (uint32_t)location;
+			break;
+
+		default:
+			pr_err("%s: unknown ADD relocation: %u\n",
+			       module->name,
+			       ELF32_R_TYPE(rela[i].r_info));
+			return -ENOEXEC;
+		}
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+notrace int module_trampoline_target(struct module *mod, unsigned long addr,
+				     unsigned long *target)
+{
+	ppc_inst_t jmp[4];
+
+	/* Find where the trampoline jumps to */
+	if (copy_inst_from_kernel_nofault(jmp, (void *)addr))
+		return -EFAULT;
+	if (__copy_inst_from_kernel_nofault(jmp + 1, (void *)addr + 4))
+		return -EFAULT;
+	if (__copy_inst_from_kernel_nofault(jmp + 2, (void *)addr + 8))
+		return -EFAULT;
+	if (__copy_inst_from_kernel_nofault(jmp + 3, (void *)addr + 12))
+		return -EFAULT;
+
+	/* verify that this is what we expect it to be */
+	if ((ppc_inst_val(jmp[0]) & 0xffff0000) != PPC_RAW_LIS(_R12, 0))
+		return -EINVAL;
+	if ((ppc_inst_val(jmp[1]) & 0xffff0000) != PPC_RAW_ADDI(_R12, _R12, 0))
+		return -EINVAL;
+	if (ppc_inst_val(jmp[2]) != PPC_RAW_MTCTR(_R12))
+		return -EINVAL;
+	if (ppc_inst_val(jmp[3]) != PPC_RAW_BCTR())
+		return -EINVAL;
+
+	addr = (ppc_inst_val(jmp[1]) & 0xffff) | ((ppc_inst_val(jmp[0]) & 0xffff) << 16);
+	if (addr & 0x8000)
+		addr -= 0x10000;
+
+	*target = addr;
+
+	return 0;
+}
+
+int module_finalize_ftrace(struct module *module, const Elf_Shdr *sechdrs)
+{
+	module->arch.tramp = do_plt_call(module->mem[MOD_TEXT].base,
+					 (unsigned long)ftrace_caller,
+					 sechdrs, module);
+	if (!module->arch.tramp)
+		return -ENOENT;
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+	module->arch.tramp_regs = do_plt_call(module->mem[MOD_TEXT].base,
+					      (unsigned long)ftrace_regs_caller,
+					      sechdrs, module);
+	if (!module->arch.tramp_regs)
+		return -ENOENT;
+#endif
+
+	return 0;
+}
+#endif