cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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module.c (4095B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Kernel module loader for Hexagon
      4 *
      5 * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
      6 */
      7
      8#include <asm/module.h>
      9#include <linux/elf.h>
     10#include <linux/module.h>
     11#include <linux/moduleloader.h>
     12#include <linux/vmalloc.h>
     13
     14#if 0
     15#define DEBUGP printk
     16#else
     17#define DEBUGP(fmt , ...)
     18#endif
     19
     20/*
     21 * module_frob_arch_sections - tweak got/plt sections.
     22 * @hdr - pointer to elf header
     23 * @sechdrs - pointer to elf load section headers
     24 * @secstrings - symbol names
     25 * @mod - pointer to module
     26 */
     27int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
     28				char *secstrings,
     29				struct module *mod)
     30{
     31	unsigned int i;
     32	int found = 0;
     33
     34	/* Look for .plt and/or .got.plt and/or .init.plt sections */
     35	for (i = 0; i < hdr->e_shnum; i++) {
     36		DEBUGP("Section %d is %s\n", i,
     37		       secstrings + sechdrs[i].sh_name);
     38		if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0)
     39			found = i+1;
     40		if (strcmp(secstrings + sechdrs[i].sh_name, ".got.plt") == 0)
     41			found = i+1;
     42		if (strcmp(secstrings + sechdrs[i].sh_name, ".rela.plt") == 0)
     43			found = i+1;
     44	}
     45
     46	/* At this time, we don't support modules comiled with -shared */
     47	if (found) {
     48		printk(KERN_WARNING
     49			"Module '%s' contains unexpected .plt/.got sections.\n",
     50			mod->name);
     51		/*  return -ENOEXEC;  */
     52	}
     53
     54	return 0;
     55}
     56
     57/*
     58 * apply_relocate_add - perform rela relocations.
     59 * @sechdrs - pointer to section headers
     60 * @strtab - some sort of start address?
     61 * @symindex - symbol index offset or something?
     62 * @relsec - address to relocate to?
     63 * @module - pointer to module
     64 *
     65 * Perform rela relocations.
     66 */
     67int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
     68			unsigned int symindex, unsigned int relsec,
     69			struct module *module)
     70{
     71	unsigned int i;
     72	Elf32_Sym *sym;
     73	uint32_t *location;
     74	uint32_t value;
     75	unsigned int nrelocs = sechdrs[relsec].sh_size / sizeof(Elf32_Rela);
     76	Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr;
     77	Elf32_Word sym_info = sechdrs[relsec].sh_info;
     78	Elf32_Sym *sym_base = (Elf32_Sym *) sechdrs[symindex].sh_addr;
     79	void *loc_base = (void *) sechdrs[sym_info].sh_addr;
     80
     81	DEBUGP("Applying relocations in section %u to section %u base=%p\n",
     82	       relsec, sym_info, loc_base);
     83
     84	for (i = 0; i < nrelocs; i++) {
     85
     86		/* Symbol to relocate */
     87		sym = sym_base + ELF32_R_SYM(rela[i].r_info);
     88
     89		/* Where to make the change */
     90		location = loc_base + rela[i].r_offset;
     91
     92		/* `Everything is relative'. */
     93		value = sym->st_value + rela[i].r_addend;
     94
     95		DEBUGP("%d: value=%08x loc=%p reloc=%d symbol=%s\n",
     96		       i, value, location, ELF32_R_TYPE(rela[i].r_info),
     97		       sym->st_name ?
     98		       &strtab[sym->st_name] : "(anonymous)");
     99
    100		switch (ELF32_R_TYPE(rela[i].r_info)) {
    101		case R_HEXAGON_B22_PCREL: {
    102			int dist = (int)(value - (uint32_t)location);
    103			if ((dist < -0x00800000) ||
    104			    (dist >= 0x00800000)) {
    105				printk(KERN_ERR
    106				       "%s: %s: %08x=%08x-%08x %s\n",
    107				       module->name,
    108				       "R_HEXAGON_B22_PCREL reloc out of range",
    109				       dist, value, (uint32_t)location,
    110				       sym->st_name ?
    111				       &strtab[sym->st_name] : "(anonymous)");
    112				return -ENOEXEC;
    113			}
    114			DEBUGP("B22_PCREL contents: %08X.\n", *location);
    115			*location &= ~0x01ff3fff;
    116			*location |= 0x00003fff & dist;
    117			*location |= 0x01ff0000 & (dist<<2);
    118			DEBUGP("Contents after reloc: %08x\n", *location);
    119			break;
    120		}
    121		case R_HEXAGON_HI16:
    122			value = (value>>16) & 0xffff;
    123			fallthrough;
    124		case R_HEXAGON_LO16:
    125			*location &= ~0x00c03fff;
    126			*location |= value & 0x3fff;
    127			*location |= (value & 0xc000) << 8;
    128			break;
    129		case R_HEXAGON_32:
    130			*location = value;
    131			break;
    132		case R_HEXAGON_32_PCREL:
    133			*location = value - (uint32_t)location;
    134			break;
    135		case R_HEXAGON_PLT_B22_PCREL:
    136		case R_HEXAGON_GOTOFF_LO16:
    137		case R_HEXAGON_GOTOFF_HI16:
    138			printk(KERN_ERR "%s: GOT/PLT relocations unsupported\n",
    139			       module->name);
    140			return -ENOEXEC;
    141		default:
    142			printk(KERN_ERR "%s: unknown relocation: %u\n",
    143			       module->name,
    144			       ELF32_R_TYPE(rela[i].r_info));
    145			return -ENOEXEC;
    146		}
    147	}
    148	return 0;
    149}