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91 lines
2.4 KiB
91 lines
2.4 KiB
/* |
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* livepatch.c - x86-specific Kernel Live Patching Core |
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* |
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* Copyright (C) 2014 Seth Jennings <sjenning@redhat.com> |
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* Copyright (C) 2014 SUSE |
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* |
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* This program is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU General Public License |
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* as published by the Free Software Foundation; either version 2 |
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* of the License, or (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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* |
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* You should have received a copy of the GNU General Public License |
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* along with this program; if not, see <http://www.gnu.org/licenses/>. |
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*/ |
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#include <linux/module.h> |
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#include <linux/uaccess.h> |
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#include <asm/cacheflush.h> |
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#include <asm/page_types.h> |
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#include <asm/elf.h> |
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#include <asm/livepatch.h> |
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/** |
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* klp_write_module_reloc() - write a relocation in a module |
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* @mod: module in which the section to be modified is found |
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* @type: ELF relocation type (see asm/elf.h) |
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* @loc: address that the relocation should be written to |
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* @value: relocation value (sym address + addend) |
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* |
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* This function writes a relocation to the specified location for |
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* a particular module. |
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*/ |
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int klp_write_module_reloc(struct module *mod, unsigned long type, |
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unsigned long loc, unsigned long value) |
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{ |
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int ret, numpages, size = 4; |
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bool readonly; |
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unsigned long val; |
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unsigned long core = (unsigned long)mod->module_core; |
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unsigned long core_size = mod->core_size; |
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switch (type) { |
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case R_X86_64_NONE: |
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return 0; |
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case R_X86_64_64: |
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val = value; |
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size = 8; |
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break; |
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case R_X86_64_32: |
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val = (u32)value; |
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break; |
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case R_X86_64_32S: |
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val = (s32)value; |
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break; |
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case R_X86_64_PC32: |
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val = (u32)(value - loc); |
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break; |
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default: |
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/* unsupported relocation type */ |
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return -EINVAL; |
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} |
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if (loc < core || loc >= core + core_size) |
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/* loc does not point to any symbol inside the module */ |
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return -EINVAL; |
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readonly = false; |
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#ifdef CONFIG_DEBUG_SET_MODULE_RONX |
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if (loc < core + mod->core_ro_size) |
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readonly = true; |
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#endif |
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/* determine if the relocation spans a page boundary */ |
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numpages = ((loc & PAGE_MASK) == ((loc + size) & PAGE_MASK)) ? 1 : 2; |
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if (readonly) |
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set_memory_rw(loc & PAGE_MASK, numpages); |
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ret = probe_kernel_write((void *)loc, &val, size); |
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if (readonly) |
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set_memory_ro(loc & PAGE_MASK, numpages); |
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return ret; |
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}
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