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#ifndef _ASM_POWERPC_CODE_PATCHING_H
#define _ASM_POWERPC_CODE_PATCHING_H
/*
* 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 <asm/types.h>
#include <asm/ppc-opcode.h>
#include <linux/string.h>
#include <linux/kallsyms.h>
/* Flags for create_branch:
* "b" == create_branch(addr, target, 0);
* "ba" == create_branch(addr, target, BRANCH_ABSOLUTE);
* "bl" == create_branch(addr, target, BRANCH_SET_LINK);
* "bla" == create_branch(addr, target, BRANCH_ABSOLUTE | BRANCH_SET_LINK);
*/
#define BRANCH_SET_LINK 0x1
#define BRANCH_ABSOLUTE 0x2
bool is_offset_in_branch_range(long offset);
unsigned int create_branch(const unsigned int *addr,
unsigned long target, int flags);
unsigned int create_cond_branch(const unsigned int *addr,
unsigned long target, int flags);
int patch_branch(unsigned int *addr, unsigned long target, int flags);
int patch_instruction(unsigned int *addr, unsigned int instr);
int instr_is_relative_branch(unsigned int instr);
int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr);
unsigned long branch_target(const unsigned int *instr);
unsigned int translate_branch(const unsigned int *dest,
const unsigned int *src);
extern bool is_conditional_branch(unsigned int instr);
#ifdef CONFIG_PPC_BOOK3E_64
void __patch_exception(int exc, unsigned long addr);
#define patch_exception(exc, name) do { \
extern unsigned int name; \
__patch_exception((exc), (unsigned long)&name); \
} while (0)
#endif
#define OP_RT_RA_MASK 0xffff0000UL
#define LIS_R2 0x3c020000UL
#define ADDIS_R2_R12 0x3c4c0000UL
#define ADDI_R2_R2 0x38420000UL
static inline unsigned long ppc_function_entry(void *func)
{
#ifdef PPC64_ELF_ABI_v2
u32 *insn = func;
/*
* A PPC64 ABIv2 function may have a local and a global entry
* point. We need to use the local entry point when patching
* functions, so identify and step over the global entry point
* sequence.
*
* The global entry point sequence is always of the form:
*
* addis r2,r12,XXXX
* addi r2,r2,XXXX
*
* A linker optimisation may convert the addis to lis:
*
* lis r2,XXXX
* addi r2,r2,XXXX
*/
if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2))
return (unsigned long)(insn + 2);
else
return (unsigned long)func;
#elif defined(PPC64_ELF_ABI_v1)
/*
* On PPC64 ABIv1 the function pointer actually points to the
* function's descriptor. The first entry in the descriptor is the
* address of the function text.
*
* However, we may also receive pointer to an assembly symbol. To
* detect that, we first check if the function pointer we receive
* already points to kernel/module text and we only dereference it
* if it doesn't.
*/
if (kernel_text_address((unsigned long)func))
return (unsigned long)func;
else
return ((func_descr_t *)func)->entry;
#else
return (unsigned long)func;
#endif
}
static inline unsigned long ppc_global_function_entry(void *func)
{
#ifdef PPC64_ELF_ABI_v2
/* PPC64 ABIv2 the global entry point is at the address */
return (unsigned long)func;
#else
/* All other cases there is no change vs ppc_function_entry() */
return ppc_function_entry(func);
#endif
}
/*
* Wrapper around kallsyms_lookup() to return function entry address:
* - For ABIv1, we lookup the dot variant.
* - For ABIv2, we return the local entry point.
*/
static inline unsigned long ppc_kallsyms_lookup_name(const char *name)
{
unsigned long addr;
#ifdef PPC64_ELF_ABI_v1
/* check for dot variant */
char dot_name[1 + KSYM_NAME_LEN];
bool dot_appended = false;
if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN)
return 0;
if (name[0] != '.') {
dot_name[0] = '.';
dot_name[1] = '\0';
strlcat(dot_name, name, sizeof(dot_name));
dot_appended = true;
} else {
dot_name[0] = '\0';
strlcat(dot_name, name, sizeof(dot_name));
}
addr = kallsyms_lookup_name(dot_name);
if (!addr && dot_appended)
/* Let's try the original non-dot symbol lookup */
addr = kallsyms_lookup_name(name);
#elif defined(PPC64_ELF_ABI_v2)
addr = kallsyms_lookup_name(name);
if (addr)
addr = ppc_function_entry((void *)addr);
#else
addr = kallsyms_lookup_name(name);
#endif
return addr;
}
#ifdef CONFIG_PPC64
/*
* Some instruction encodings commonly used in dynamic ftracing
* and function live patching.
*/
/* This must match the definition of STK_GOT in <asm/ppc_asm.h> */
#ifdef PPC64_ELF_ABI_v2
#define R2_STACK_OFFSET 24
#else
#define R2_STACK_OFFSET 40
#endif
#define PPC_INST_LD_TOC (PPC_INST_LD | ___PPC_RT(__REG_R2) | \
___PPC_RA(__REG_R1) | R2_STACK_OFFSET)
/* usually preceded by a mflr r0 */
#define PPC_INST_STD_LR (PPC_INST_STD | ___PPC_RS(__REG_R0) | \
___PPC_RA(__REG_R1) | PPC_LR_STKOFF)
#endif /* CONFIG_PPC64 */
#endif /* _ASM_POWERPC_CODE_PATCHING_H */
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