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https://github.com/Evolution-X-Devices/kernel_google_b1c1
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48a5c81f3f
commit b45ba4a51cde29b2939365ef0c07ad34c8321789 upstream.
Commit 51c3c62b58b3 ("powerpc: Avoid code patching freed init
sections") accesses 'init_mem_is_free' flag too early, before the
kernel is relocated. This provokes early boot failure (before the
console is active).
As it is not necessary to do this verification that early, this
patch moves the test into patch_instruction() instead of
__patch_instruction().
This modification also has the advantage of avoiding unnecessary
remappings.
Fixes: 51c3c62b58b3 ("powerpc: Avoid code patching freed init sections")
Cc: stable@vger.kernel.org # 4.13+
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
500 lines
14 KiB
C
500 lines
14 KiB
C
/*
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* Copyright 2008 Michael Ellerman, IBM Corporation.
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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
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/kernel.h>
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#include <linux/vmalloc.h>
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#include <linux/init.h>
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#include <linux/mm.h>
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#include <asm/page.h>
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#include <asm/code-patching.h>
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#include <asm/uaccess.h>
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#include <asm/setup.h>
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#include <asm/sections.h>
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int patch_instruction(unsigned int *addr, unsigned int instr)
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{
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int err;
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/* Make sure we aren't patching a freed init section */
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if (*PTRRELOC(&init_mem_is_free) && init_section_contains(addr, 4)) {
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pr_debug("Skipping init section patching addr: 0x%px\n", addr);
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return 0;
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}
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__put_user_size(instr, addr, 4, err);
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if (err)
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return err;
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asm ("dcbst 0, %0; sync; icbi 0,%0; sync; isync" : : "r" (addr));
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return 0;
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}
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int patch_branch(unsigned int *addr, unsigned long target, int flags)
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{
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return patch_instruction(addr, create_branch(addr, target, flags));
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}
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int patch_branch_site(s32 *site, unsigned long target, int flags)
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{
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unsigned int *addr;
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addr = (unsigned int *)((unsigned long)site + *site);
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return patch_instruction(addr, create_branch(addr, target, flags));
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}
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int patch_instruction_site(s32 *site, unsigned int instr)
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{
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unsigned int *addr;
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addr = (unsigned int *)((unsigned long)site + *site);
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return patch_instruction(addr, instr);
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}
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unsigned int create_branch(const unsigned int *addr,
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unsigned long target, int flags)
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{
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unsigned int instruction;
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long offset;
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offset = target;
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if (! (flags & BRANCH_ABSOLUTE))
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offset = offset - (unsigned long)addr;
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/* Check we can represent the target in the instruction format */
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if (offset < -0x2000000 || offset > 0x1fffffc || offset & 0x3)
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return 0;
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/* Mask out the flags and target, so they don't step on each other. */
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instruction = 0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC);
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return instruction;
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}
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unsigned int create_cond_branch(const unsigned int *addr,
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unsigned long target, int flags)
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{
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unsigned int instruction;
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long offset;
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offset = target;
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if (! (flags & BRANCH_ABSOLUTE))
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offset = offset - (unsigned long)addr;
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/* Check we can represent the target in the instruction format */
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if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3)
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return 0;
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/* Mask out the flags and target, so they don't step on each other. */
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instruction = 0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC);
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return instruction;
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}
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static unsigned int branch_opcode(unsigned int instr)
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{
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return (instr >> 26) & 0x3F;
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}
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static int instr_is_branch_iform(unsigned int instr)
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{
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return branch_opcode(instr) == 18;
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}
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static int instr_is_branch_bform(unsigned int instr)
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{
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return branch_opcode(instr) == 16;
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}
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int instr_is_relative_branch(unsigned int instr)
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{
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if (instr & BRANCH_ABSOLUTE)
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return 0;
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return instr_is_branch_iform(instr) || instr_is_branch_bform(instr);
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}
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int instr_is_relative_link_branch(unsigned int instr)
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{
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return instr_is_relative_branch(instr) && (instr & BRANCH_SET_LINK);
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}
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static unsigned long branch_iform_target(const unsigned int *instr)
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{
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signed long imm;
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imm = *instr & 0x3FFFFFC;
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/* If the top bit of the immediate value is set this is negative */
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if (imm & 0x2000000)
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imm -= 0x4000000;
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if ((*instr & BRANCH_ABSOLUTE) == 0)
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imm += (unsigned long)instr;
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return (unsigned long)imm;
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}
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static unsigned long branch_bform_target(const unsigned int *instr)
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{
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signed long imm;
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imm = *instr & 0xFFFC;
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/* If the top bit of the immediate value is set this is negative */
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if (imm & 0x8000)
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imm -= 0x10000;
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if ((*instr & BRANCH_ABSOLUTE) == 0)
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imm += (unsigned long)instr;
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return (unsigned long)imm;
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}
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unsigned long branch_target(const unsigned int *instr)
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{
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if (instr_is_branch_iform(*instr))
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return branch_iform_target(instr);
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else if (instr_is_branch_bform(*instr))
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return branch_bform_target(instr);
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return 0;
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}
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int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr)
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{
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if (instr_is_branch_iform(*instr) || instr_is_branch_bform(*instr))
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return branch_target(instr) == addr;
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return 0;
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}
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unsigned int translate_branch(const unsigned int *dest, const unsigned int *src)
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{
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unsigned long target;
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target = branch_target(src);
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if (instr_is_branch_iform(*src))
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return create_branch(dest, target, *src);
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else if (instr_is_branch_bform(*src))
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return create_cond_branch(dest, target, *src);
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return 0;
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}
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#ifdef CONFIG_PPC_BOOK3E_64
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void __patch_exception(int exc, unsigned long addr)
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{
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extern unsigned int interrupt_base_book3e;
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unsigned int *ibase = &interrupt_base_book3e;
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/* Our exceptions vectors start with a NOP and -then- a branch
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* to deal with single stepping from userspace which stops on
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* the second instruction. Thus we need to patch the second
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* instruction of the exception, not the first one
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*/
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patch_branch(ibase + (exc / 4) + 1, addr, 0);
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}
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#endif
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#ifdef CONFIG_CODE_PATCHING_SELFTEST
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static void __init test_trampoline(void)
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{
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asm ("nop;\n");
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}
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#define check(x) \
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if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__);
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static void __init test_branch_iform(void)
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{
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unsigned int instr;
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unsigned long addr;
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addr = (unsigned long)&instr;
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/* The simplest case, branch to self, no flags */
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check(instr_is_branch_iform(0x48000000));
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/* All bits of target set, and flags */
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check(instr_is_branch_iform(0x4bffffff));
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/* High bit of opcode set, which is wrong */
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check(!instr_is_branch_iform(0xcbffffff));
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/* Middle bits of opcode set, which is wrong */
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check(!instr_is_branch_iform(0x7bffffff));
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/* Simplest case, branch to self with link */
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check(instr_is_branch_iform(0x48000001));
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/* All bits of targets set */
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check(instr_is_branch_iform(0x4bfffffd));
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/* Some bits of targets set */
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check(instr_is_branch_iform(0x4bff00fd));
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/* Must be a valid branch to start with */
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check(!instr_is_branch_iform(0x7bfffffd));
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/* Absolute branch to 0x100 */
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instr = 0x48000103;
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check(instr_is_branch_to_addr(&instr, 0x100));
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/* Absolute branch to 0x420fc */
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instr = 0x480420ff;
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check(instr_is_branch_to_addr(&instr, 0x420fc));
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/* Maximum positive relative branch, + 20MB - 4B */
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instr = 0x49fffffc;
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check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC));
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/* Smallest negative relative branch, - 4B */
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instr = 0x4bfffffc;
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check(instr_is_branch_to_addr(&instr, addr - 4));
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/* Largest negative relative branch, - 32 MB */
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instr = 0x4a000000;
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check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
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/* Branch to self, with link */
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instr = create_branch(&instr, addr, BRANCH_SET_LINK);
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check(instr_is_branch_to_addr(&instr, addr));
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/* Branch to self - 0x100, with link */
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instr = create_branch(&instr, addr - 0x100, BRANCH_SET_LINK);
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check(instr_is_branch_to_addr(&instr, addr - 0x100));
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/* Branch to self + 0x100, no link */
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instr = create_branch(&instr, addr + 0x100, 0);
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check(instr_is_branch_to_addr(&instr, addr + 0x100));
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/* Maximum relative negative offset, - 32 MB */
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instr = create_branch(&instr, addr - 0x2000000, BRANCH_SET_LINK);
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check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
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/* Out of range relative negative offset, - 32 MB + 4*/
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instr = create_branch(&instr, addr - 0x2000004, BRANCH_SET_LINK);
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check(instr == 0);
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/* Out of range relative positive offset, + 32 MB */
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instr = create_branch(&instr, addr + 0x2000000, BRANCH_SET_LINK);
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check(instr == 0);
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/* Unaligned target */
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instr = create_branch(&instr, addr + 3, BRANCH_SET_LINK);
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check(instr == 0);
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/* Check flags are masked correctly */
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instr = create_branch(&instr, addr, 0xFFFFFFFC);
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check(instr_is_branch_to_addr(&instr, addr));
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check(instr == 0x48000000);
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}
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static void __init test_create_function_call(void)
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{
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unsigned int *iptr;
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unsigned long dest;
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/* Check we can create a function call */
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iptr = (unsigned int *)ppc_function_entry(test_trampoline);
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dest = ppc_function_entry(test_create_function_call);
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patch_instruction(iptr, create_branch(iptr, dest, BRANCH_SET_LINK));
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check(instr_is_branch_to_addr(iptr, dest));
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}
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static void __init test_branch_bform(void)
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{
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unsigned long addr;
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unsigned int *iptr, instr, flags;
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iptr = &instr;
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addr = (unsigned long)iptr;
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/* The simplest case, branch to self, no flags */
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check(instr_is_branch_bform(0x40000000));
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/* All bits of target set, and flags */
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check(instr_is_branch_bform(0x43ffffff));
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/* High bit of opcode set, which is wrong */
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check(!instr_is_branch_bform(0xc3ffffff));
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/* Middle bits of opcode set, which is wrong */
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check(!instr_is_branch_bform(0x7bffffff));
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/* Absolute conditional branch to 0x100 */
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instr = 0x43ff0103;
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check(instr_is_branch_to_addr(&instr, 0x100));
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/* Absolute conditional branch to 0x20fc */
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instr = 0x43ff20ff;
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check(instr_is_branch_to_addr(&instr, 0x20fc));
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/* Maximum positive relative conditional branch, + 32 KB - 4B */
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instr = 0x43ff7ffc;
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check(instr_is_branch_to_addr(&instr, addr + 0x7FFC));
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/* Smallest negative relative conditional branch, - 4B */
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instr = 0x43fffffc;
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check(instr_is_branch_to_addr(&instr, addr - 4));
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/* Largest negative relative conditional branch, - 32 KB */
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instr = 0x43ff8000;
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check(instr_is_branch_to_addr(&instr, addr - 0x8000));
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/* All condition code bits set & link */
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flags = 0x3ff000 | BRANCH_SET_LINK;
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/* Branch to self */
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instr = create_cond_branch(iptr, addr, flags);
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check(instr_is_branch_to_addr(&instr, addr));
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/* Branch to self - 0x100 */
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instr = create_cond_branch(iptr, addr - 0x100, flags);
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check(instr_is_branch_to_addr(&instr, addr - 0x100));
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/* Branch to self + 0x100 */
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instr = create_cond_branch(iptr, addr + 0x100, flags);
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check(instr_is_branch_to_addr(&instr, addr + 0x100));
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/* Maximum relative negative offset, - 32 KB */
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instr = create_cond_branch(iptr, addr - 0x8000, flags);
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check(instr_is_branch_to_addr(&instr, addr - 0x8000));
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/* Out of range relative negative offset, - 32 KB + 4*/
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instr = create_cond_branch(iptr, addr - 0x8004, flags);
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check(instr == 0);
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/* Out of range relative positive offset, + 32 KB */
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instr = create_cond_branch(iptr, addr + 0x8000, flags);
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check(instr == 0);
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/* Unaligned target */
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instr = create_cond_branch(iptr, addr + 3, flags);
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check(instr == 0);
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/* Check flags are masked correctly */
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instr = create_cond_branch(iptr, addr, 0xFFFFFFFC);
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check(instr_is_branch_to_addr(&instr, addr));
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check(instr == 0x43FF0000);
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}
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static void __init test_translate_branch(void)
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{
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unsigned long addr;
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unsigned int *p, *q;
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void *buf;
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buf = vmalloc(PAGE_ALIGN(0x2000000 + 1));
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check(buf);
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if (!buf)
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return;
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/* Simple case, branch to self moved a little */
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p = buf;
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addr = (unsigned long)p;
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patch_branch(p, addr, 0);
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check(instr_is_branch_to_addr(p, addr));
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q = p + 1;
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patch_instruction(q, translate_branch(q, p));
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check(instr_is_branch_to_addr(q, addr));
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/* Maximum negative case, move b . to addr + 32 MB */
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p = buf;
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addr = (unsigned long)p;
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patch_branch(p, addr, 0);
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q = buf + 0x2000000;
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patch_instruction(q, translate_branch(q, p));
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check(instr_is_branch_to_addr(p, addr));
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check(instr_is_branch_to_addr(q, addr));
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check(*q == 0x4a000000);
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/* Maximum positive case, move x to x - 32 MB + 4 */
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p = buf + 0x2000000;
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addr = (unsigned long)p;
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patch_branch(p, addr, 0);
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q = buf + 4;
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patch_instruction(q, translate_branch(q, p));
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check(instr_is_branch_to_addr(p, addr));
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check(instr_is_branch_to_addr(q, addr));
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check(*q == 0x49fffffc);
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/* Jump to x + 16 MB moved to x + 20 MB */
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p = buf;
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addr = 0x1000000 + (unsigned long)buf;
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patch_branch(p, addr, BRANCH_SET_LINK);
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q = buf + 0x1400000;
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patch_instruction(q, translate_branch(q, p));
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check(instr_is_branch_to_addr(p, addr));
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check(instr_is_branch_to_addr(q, addr));
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/* Jump to x + 16 MB moved to x - 16 MB + 4 */
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p = buf + 0x1000000;
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addr = 0x2000000 + (unsigned long)buf;
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patch_branch(p, addr, 0);
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q = buf + 4;
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patch_instruction(q, translate_branch(q, p));
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check(instr_is_branch_to_addr(p, addr));
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check(instr_is_branch_to_addr(q, addr));
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/* Conditional branch tests */
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/* Simple case, branch to self moved a little */
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p = buf;
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addr = (unsigned long)p;
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patch_instruction(p, create_cond_branch(p, addr, 0));
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check(instr_is_branch_to_addr(p, addr));
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q = p + 1;
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patch_instruction(q, translate_branch(q, p));
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check(instr_is_branch_to_addr(q, addr));
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/* Maximum negative case, move b . to addr + 32 KB */
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p = buf;
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addr = (unsigned long)p;
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patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
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q = buf + 0x8000;
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patch_instruction(q, translate_branch(q, p));
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check(instr_is_branch_to_addr(p, addr));
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check(instr_is_branch_to_addr(q, addr));
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check(*q == 0x43ff8000);
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/* Maximum positive case, move x to x - 32 KB + 4 */
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p = buf + 0x8000;
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addr = (unsigned long)p;
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patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
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q = buf + 4;
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patch_instruction(q, translate_branch(q, p));
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check(instr_is_branch_to_addr(p, addr));
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check(instr_is_branch_to_addr(q, addr));
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check(*q == 0x43ff7ffc);
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/* Jump to x + 12 KB moved to x + 20 KB */
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p = buf;
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addr = 0x3000 + (unsigned long)buf;
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patch_instruction(p, create_cond_branch(p, addr, BRANCH_SET_LINK));
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q = buf + 0x5000;
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patch_instruction(q, translate_branch(q, p));
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check(instr_is_branch_to_addr(p, addr));
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check(instr_is_branch_to_addr(q, addr));
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/* Jump to x + 8 KB moved to x - 8 KB + 4 */
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p = buf + 0x2000;
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addr = 0x4000 + (unsigned long)buf;
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patch_instruction(p, create_cond_branch(p, addr, 0));
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q = buf + 4;
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patch_instruction(q, translate_branch(q, p));
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check(instr_is_branch_to_addr(p, addr));
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check(instr_is_branch_to_addr(q, addr));
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/* Free the buffer we were using */
|
|
vfree(buf);
|
|
}
|
|
|
|
static int __init test_code_patching(void)
|
|
{
|
|
printk(KERN_DEBUG "Running code patching self-tests ...\n");
|
|
|
|
test_branch_iform();
|
|
test_branch_bform();
|
|
test_create_function_call();
|
|
test_translate_branch();
|
|
|
|
return 0;
|
|
}
|
|
late_initcall(test_code_patching);
|
|
|
|
#endif /* CONFIG_CODE_PATCHING_SELFTEST */
|