[patch v3 13/36] Hexagon: Support dynamic module loading.

Richard Kuo
2011-09-09T01:09:00Z

[-- Attachment #1: module.diff --]
[-- Type: text/plain, Size: 5678 bytes --]

Modules should be compiled as ordinary .o's; shared objects are not
supported.

Deleted module functions that already have generic equivalents.

Signed-off-by: Linas Vepstas <linas@codeaurora.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>

---
arch/hexagon/kernel/module.c | 162 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 162 insertions(+)

Index: linux-hexagon-kernel/arch/hexagon/kernel/module.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-hexagon-kernel/arch/hexagon/kernel/module.c 2011-09-07 13:00:31.090647031 -0500
@@ -0,0 +1,162 @@
+/*
+ * Kernel module loader for Hexagon
+ *
+ * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+#include <asm/module.h>
+#include <linux/elf.h>
+#include <linux/module.h>
+#include <linux/moduleloader.h>
+#include <linux/vmalloc.h>
+
+#if 0
+#define DEBUGP printk
+#else
+#define DEBUGP(fmt , ...)
+#endif
+
+/*
+ * module_frob_arch_sections - tweak got/plt sections.
+ * @hdr - pointer to elf header
+ * @sechdrs - pointer to elf load section headers
+ * @secstrings - symbol names
+ * @mod - pointer to module
+ */
+int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
+ char *secstrings,
+ struct module *mod)
+{
+ unsigned int i;
+ int found = 0;
+
+ /* Look for .plt and/or .got.plt and/or .init.plt sections */
+ for (i = 0; i < hdr->e_shnum; i++) {
+ DEBUGP("Section %d is %s\n", i,
+ secstrings + sechdrs[i].sh_name);
+ if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0)
+ found = i+1;
+ if (strcmp(secstrings + sechdrs[i].sh_name, ".got.plt") == 0)
+ found = i+1;
+ if (strcmp(secstrings + sechdrs[i].sh_name, ".rela.plt") == 0)
+ found = i+1;
+ }
+
+ /* At this time, we don't support modules comiled with -shared */
+ if (found) {
+ printk(KERN_WARNING
+ "Module '%s' contains unexpected .plt/.got sections.\n",
+ mod->name);
+ /* return -ENOEXEC; */
+ }
+
+ return 0;
+}
+
+/*
+ * apply_relocate_add - perform rela relocations.
+ * @sechdrs - pointer to section headers
+ * @strtab - some sort of start address?
+ * @symindex - symbol index offset or something?
+ * @relsec - address to relocate to?
+ * @module - pointer to module
+ *
+ * Perform rela relocations.
+ */
+int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
+ unsigned int symindex, unsigned int relsec,
+ struct module *module)
+{
+ unsigned int i;
+ Elf32_Sym *sym;
+ uint32_t *location;
+ uint32_t value;
+ unsigned int nrelocs = sechdrs[relsec].sh_size / sizeof(Elf32_Rela);
+ Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr;
+ Elf32_Word sym_info = sechdrs[relsec].sh_info;
+ Elf32_Sym *sym_base = (Elf32_Sym *) sechdrs[symindex].sh_addr;
+ void *loc_base = (void *) sechdrs[sym_info].sh_addr;
+
+ DEBUGP("Applying relocations in section %u to section %u base=%p\n",
+ relsec, sym_info, loc_base);
+
+ for (i = 0; i < nrelocs; i++) {
+
+ /* Symbol to relocate */
+ sym = sym_base + ELF32_R_SYM(rela[i].r_info);
+
+ /* Where to make the change */
+ location = loc_base + rela[i].r_offset;
+
+ /* `Everything is relative'. */
+ value = sym->st_value + rela[i].r_addend;
+
+ DEBUGP("%d: value=%08x loc=%p reloc=%d symbol=%s\n",
+ i, value, location, ELF32_R_TYPE(rela[i].r_info),
+ sym->st_name ?
+ &strtab[sym->st_name] : "(anonymous)");
+
+ switch (ELF32_R_TYPE(rela[i].r_info)) {
+ case R_HEXAGON_B22_PCREL: {
+ int dist = (int)(value - (uint32_t)location);
+ if ((dist < -0x00800000) ||
+ (dist >= 0x00800000)) {
+ printk(KERN_ERR
+ "%s: %s: %08x=%08x-%08x %s\n",
+ module->name,
+ "R_HEXAGON_B22_PCREL reloc out of range",
+ dist, value, (uint32_t)location,
+ sym->st_name ?
+ &strtab[sym->st_name] : "(anonymous)");
+ return -ENOEXEC;
+ }
+ DEBUGP("B22_PCREL contents: %08X.\n", *location);
+ *location &= ~0x01ff3fff;
+ *location |= 0x00003fff & dist;
+ *location |= 0x01ff0000 & (dist<<2);
+ DEBUGP("Contents after reloc: %08x\n", *location);
+ break;
+ }
+ case R_HEXAGON_HI16:
+ value = (value>>16) & 0xffff;
+ /* fallthrough */
+ case R_HEXAGON_LO16:
+ *location &= ~0x00c03fff;
+ *location |= value & 0x3fff;
+ *location |= (value & 0xc000) << 8;
+ break;
+ case R_HEXAGON_32:
+ *location = value;
+ break;
+ case R_HEXAGON_32_PCREL:
+ *location = value - (uint32_t)location;
+ break;
+ case R_HEXAGON_PLT_B22_PCREL:
+ case R_HEXAGON_GOTOFF_LO16:
+ case R_HEXAGON_GOTOFF_HI16:
+ printk(KERN_ERR "%s: GOT/PLT relocations unsupported\n",
+ module->name);
+ return -ENOEXEC;
+ default:
+ printk(KERN_ERR "%s: unknown relocation: %u\n",
+ module->name,
+ ELF32_R_TYPE(rela[i].r_info));
+ return -ENOEXEC;
+ }
+ }
+ return 0;
+}