411781a290
This commit adds some new routines for patching code, which will be used in a following commit. Signed-off-by: Michael Ellerman <michael@ellerman.id.au> Signed-off-by: Paul Mackerras <paulus@samba.org>
150 lines
3.5 KiB
C
150 lines
3.5 KiB
C
/*
|
|
* Copyright 2008 Michael Ellerman, IBM Corporation.
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License
|
|
* as published by the Free Software Foundation; either version
|
|
* 2 of the License, or (at your option) any later version.
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <asm/code-patching.h>
|
|
|
|
|
|
void patch_instruction(unsigned int *addr, unsigned int instr)
|
|
{
|
|
*addr = instr;
|
|
asm ("dcbst 0, %0; sync; icbi 0,%0; sync; isync" : : "r" (addr));
|
|
}
|
|
|
|
void patch_branch(unsigned int *addr, unsigned long target, int flags)
|
|
{
|
|
patch_instruction(addr, create_branch(addr, target, flags));
|
|
}
|
|
|
|
unsigned int create_branch(const unsigned int *addr,
|
|
unsigned long target, int flags)
|
|
{
|
|
unsigned int instruction;
|
|
long offset;
|
|
|
|
offset = target;
|
|
if (! (flags & BRANCH_ABSOLUTE))
|
|
offset = offset - (unsigned long)addr;
|
|
|
|
/* Check we can represent the target in the instruction format */
|
|
if (offset < -0x2000000 || offset > 0x1fffffc || offset & 0x3)
|
|
return 0;
|
|
|
|
/* Mask out the flags and target, so they don't step on each other. */
|
|
instruction = 0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC);
|
|
|
|
return instruction;
|
|
}
|
|
|
|
unsigned int create_cond_branch(const unsigned int *addr,
|
|
unsigned long target, int flags)
|
|
{
|
|
unsigned int instruction;
|
|
long offset;
|
|
|
|
offset = target;
|
|
if (! (flags & BRANCH_ABSOLUTE))
|
|
offset = offset - (unsigned long)addr;
|
|
|
|
/* Check we can represent the target in the instruction format */
|
|
if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3)
|
|
return 0;
|
|
|
|
/* Mask out the flags and target, so they don't step on each other. */
|
|
instruction = 0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC);
|
|
|
|
return instruction;
|
|
}
|
|
|
|
static unsigned int branch_opcode(unsigned int instr)
|
|
{
|
|
return (instr >> 26) & 0x3F;
|
|
}
|
|
|
|
static int instr_is_branch_iform(unsigned int instr)
|
|
{
|
|
return branch_opcode(instr) == 18;
|
|
}
|
|
|
|
static int instr_is_branch_bform(unsigned int instr)
|
|
{
|
|
return branch_opcode(instr) == 16;
|
|
}
|
|
|
|
int instr_is_relative_branch(unsigned int instr)
|
|
{
|
|
if (instr & BRANCH_ABSOLUTE)
|
|
return 0;
|
|
|
|
return instr_is_branch_iform(instr) || instr_is_branch_bform(instr);
|
|
}
|
|
|
|
static unsigned long branch_iform_target(const unsigned int *instr)
|
|
{
|
|
signed long imm;
|
|
|
|
imm = *instr & 0x3FFFFFC;
|
|
|
|
/* If the top bit of the immediate value is set this is negative */
|
|
if (imm & 0x2000000)
|
|
imm -= 0x4000000;
|
|
|
|
if ((*instr & BRANCH_ABSOLUTE) == 0)
|
|
imm += (unsigned long)instr;
|
|
|
|
return (unsigned long)imm;
|
|
}
|
|
|
|
static unsigned long branch_bform_target(const unsigned int *instr)
|
|
{
|
|
signed long imm;
|
|
|
|
imm = *instr & 0xFFFC;
|
|
|
|
/* If the top bit of the immediate value is set this is negative */
|
|
if (imm & 0x8000)
|
|
imm -= 0x10000;
|
|
|
|
if ((*instr & BRANCH_ABSOLUTE) == 0)
|
|
imm += (unsigned long)instr;
|
|
|
|
return (unsigned long)imm;
|
|
}
|
|
|
|
unsigned long branch_target(const unsigned int *instr)
|
|
{
|
|
if (instr_is_branch_iform(*instr))
|
|
return branch_iform_target(instr);
|
|
else if (instr_is_branch_bform(*instr))
|
|
return branch_bform_target(instr);
|
|
|
|
return 0;
|
|
}
|
|
|
|
int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr)
|
|
{
|
|
if (instr_is_branch_iform(*instr) || instr_is_branch_bform(*instr))
|
|
return branch_target(instr) == addr;
|
|
|
|
return 0;
|
|
}
|
|
|
|
unsigned int translate_branch(const unsigned int *dest, const unsigned int *src)
|
|
{
|
|
unsigned long target;
|
|
|
|
target = branch_target(src);
|
|
|
|
if (instr_is_branch_iform(*src))
|
|
return create_branch(dest, target, *src);
|
|
else if (instr_is_branch_bform(*src))
|
|
return create_cond_branch(dest, target, *src);
|
|
|
|
return 0;
|
|
}
|