240 lines
6.5 KiB
C
240 lines
6.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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#ifndef _ASM_POWERPC_CODE_PATCHING_H
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#define _ASM_POWERPC_CODE_PATCHING_H
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/*
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* Copyright 2008, Michael Ellerman, IBM Corporation.
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*/
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#include <asm/types.h>
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#include <asm/ppc-opcode.h>
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#include <linux/string.h>
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#include <linux/kallsyms.h>
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#include <asm/asm-compat.h>
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#include <asm/inst.h>
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/* Flags for create_branch:
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* "b" == create_branch(addr, target, 0);
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* "ba" == create_branch(addr, target, BRANCH_ABSOLUTE);
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* "bl" == create_branch(addr, target, BRANCH_SET_LINK);
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* "bla" == create_branch(addr, target, BRANCH_ABSOLUTE | BRANCH_SET_LINK);
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*/
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#define BRANCH_SET_LINK 0x1
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#define BRANCH_ABSOLUTE 0x2
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DECLARE_STATIC_KEY_FALSE(init_mem_is_free);
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/*
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* Powerpc branch instruction is :
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*
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* 0 6 30 31
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* +---------+----------------+---+---+
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* | opcode | LI |AA |LK |
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* +---------+----------------+---+---+
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* Where AA = 0 and LK = 0
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*
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* LI is a signed 24 bits integer. The real branch offset is computed
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* by: imm32 = SignExtend(LI:'0b00', 32);
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*
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* So the maximum forward branch should be:
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* (0x007fffff << 2) = 0x01fffffc = 0x1fffffc
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* The maximum backward branch should be:
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* (0xff800000 << 2) = 0xfe000000 = -0x2000000
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*/
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static inline bool is_offset_in_branch_range(long offset)
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{
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return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3));
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}
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static inline bool is_offset_in_cond_branch_range(long offset)
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{
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return offset >= -0x8000 && offset <= 0x7fff && !(offset & 0x3);
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}
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static inline int create_branch(ppc_inst_t *instr, const u32 *addr,
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unsigned long target, int flags)
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{
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long offset;
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*instr = ppc_inst(0);
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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 (!is_offset_in_branch_range(offset))
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return 1;
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/* Mask out the flags and target, so they don't step on each other. */
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*instr = ppc_inst(0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC));
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return 0;
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}
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int create_cond_branch(ppc_inst_t *instr, const u32 *addr,
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unsigned long target, int flags);
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int patch_branch(u32 *addr, unsigned long target, int flags);
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int patch_instruction(u32 *addr, ppc_inst_t instr);
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int raw_patch_instruction(u32 *addr, ppc_inst_t instr);
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static inline unsigned long patch_site_addr(s32 *site)
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{
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return (unsigned long)site + *site;
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}
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static inline int patch_instruction_site(s32 *site, ppc_inst_t instr)
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{
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return patch_instruction((u32 *)patch_site_addr(site), instr);
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}
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static inline int patch_branch_site(s32 *site, unsigned long target, int flags)
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{
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return patch_branch((u32 *)patch_site_addr(site), target, flags);
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}
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static inline int modify_instruction(unsigned int *addr, unsigned int clr,
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unsigned int set)
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{
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return patch_instruction(addr, ppc_inst((*addr & ~clr) | set));
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}
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static inline int modify_instruction_site(s32 *site, unsigned int clr, unsigned int set)
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{
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return modify_instruction((unsigned int *)patch_site_addr(site), clr, set);
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}
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static inline unsigned int branch_opcode(ppc_inst_t instr)
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{
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return ppc_inst_primary_opcode(instr) & 0x3F;
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}
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static inline int instr_is_branch_iform(ppc_inst_t instr)
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{
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return branch_opcode(instr) == 18;
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}
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static inline int instr_is_branch_bform(ppc_inst_t 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(ppc_inst_t instr);
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int instr_is_relative_link_branch(ppc_inst_t instr);
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unsigned long branch_target(const u32 *instr);
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int translate_branch(ppc_inst_t *instr, const u32 *dest, const u32 *src);
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bool is_conditional_branch(ppc_inst_t instr);
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#define OP_RT_RA_MASK 0xffff0000UL
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#define LIS_R2 (PPC_RAW_LIS(_R2, 0))
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#define ADDIS_R2_R12 (PPC_RAW_ADDIS(_R2, _R12, 0))
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#define ADDI_R2_R2 (PPC_RAW_ADDI(_R2, _R2, 0))
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static inline unsigned long ppc_function_entry(void *func)
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{
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#ifdef CONFIG_PPC64_ELF_ABI_V2
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u32 *insn = func;
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/*
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* A PPC64 ABIv2 function may have a local and a global entry
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* point. We need to use the local entry point when patching
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* functions, so identify and step over the global entry point
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* sequence.
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*
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* The global entry point sequence is always of the form:
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*
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* addis r2,r12,XXXX
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* addi r2,r2,XXXX
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*
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* A linker optimisation may convert the addis to lis:
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*
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* lis r2,XXXX
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* addi r2,r2,XXXX
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*/
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if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
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((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
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((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2))
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return (unsigned long)(insn + 2);
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else
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return (unsigned long)func;
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#elif defined(CONFIG_PPC64_ELF_ABI_V1)
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/*
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* On PPC64 ABIv1 the function pointer actually points to the
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* function's descriptor. The first entry in the descriptor is the
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* address of the function text.
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*/
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return ((struct func_desc *)func)->addr;
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#else
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return (unsigned long)func;
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#endif
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}
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static inline unsigned long ppc_global_function_entry(void *func)
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{
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#ifdef CONFIG_PPC64_ELF_ABI_V2
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/* PPC64 ABIv2 the global entry point is at the address */
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return (unsigned long)func;
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#else
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/* All other cases there is no change vs ppc_function_entry() */
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return ppc_function_entry(func);
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#endif
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}
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/*
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* Wrapper around kallsyms_lookup() to return function entry address:
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* - For ABIv1, we lookup the dot variant.
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* - For ABIv2, we return the local entry point.
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*/
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static inline unsigned long ppc_kallsyms_lookup_name(const char *name)
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{
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unsigned long addr;
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#ifdef CONFIG_PPC64_ELF_ABI_V1
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/* check for dot variant */
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char dot_name[1 + KSYM_NAME_LEN];
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bool dot_appended = false;
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if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN)
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return 0;
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if (name[0] != '.') {
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dot_name[0] = '.';
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dot_name[1] = '\0';
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strlcat(dot_name, name, sizeof(dot_name));
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dot_appended = true;
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} else {
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dot_name[0] = '\0';
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strlcat(dot_name, name, sizeof(dot_name));
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}
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addr = kallsyms_lookup_name(dot_name);
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if (!addr && dot_appended)
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/* Let's try the original non-dot symbol lookup */
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addr = kallsyms_lookup_name(name);
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#elif defined(CONFIG_PPC64_ELF_ABI_V2)
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addr = kallsyms_lookup_name(name);
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if (addr)
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addr = ppc_function_entry((void *)addr);
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#else
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addr = kallsyms_lookup_name(name);
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#endif
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return addr;
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}
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/*
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* Some instruction encodings commonly used in dynamic ftracing
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* and function live patching.
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*/
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/* This must match the definition of STK_GOT in <asm/ppc_asm.h> */
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#ifdef CONFIG_PPC64_ELF_ABI_V2
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#define R2_STACK_OFFSET 24
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#else
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#define R2_STACK_OFFSET 40
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#endif
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#define PPC_INST_LD_TOC PPC_RAW_LD(_R2, _R1, R2_STACK_OFFSET)
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/* usually preceded by a mflr r0 */
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#define PPC_INST_STD_LR PPC_RAW_STD(_R0, _R1, PPC_LR_STKOFF)
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#endif /* _ASM_POWERPC_CODE_PATCHING_H */
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