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Diffstat (limited to 'arch/powerpc/include/asm/code-patching.h')
| -rw-r--r-- | arch/powerpc/include/asm/code-patching.h | 237 |
1 files changed, 237 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/code-patching.h b/arch/powerpc/include/asm/code-patching.h new file mode 100644 index 000000000..3f881548f --- /dev/null +++ b/arch/powerpc/include/asm/code-patching.h @@ -0,0 +1,237 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +#ifndef _ASM_POWERPC_CODE_PATCHING_H +#define _ASM_POWERPC_CODE_PATCHING_H + +/* + * Copyright 2008, Michael Ellerman, IBM Corporation. + */ + +#include <asm/types.h> +#include <asm/ppc-opcode.h> +#include <linux/string.h> +#include <linux/kallsyms.h> +#include <asm/asm-compat.h> +#include <asm/inst.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 + +/* + * Powerpc branch instruction is : + * + * 0 6 30 31 + * +---------+----------------+---+---+ + * | opcode | LI |AA |LK | + * +---------+----------------+---+---+ + * Where AA = 0 and LK = 0 + * + * LI is a signed 24 bits integer. The real branch offset is computed + * by: imm32 = SignExtend(LI:'0b00', 32); + * + * So the maximum forward branch should be: + * (0x007fffff << 2) = 0x01fffffc = 0x1fffffc + * The maximum backward branch should be: + * (0xff800000 << 2) = 0xfe000000 = -0x2000000 + */ +static inline bool is_offset_in_branch_range(long offset) +{ + return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3)); +} + +static inline bool is_offset_in_cond_branch_range(long offset) +{ + return offset >= -0x8000 && offset <= 0x7fff && !(offset & 0x3); +} + +static inline int create_branch(ppc_inst_t *instr, const u32 *addr, + unsigned long target, int flags) +{ + long offset; + + *instr = ppc_inst(0); + offset = target; + if (! (flags & BRANCH_ABSOLUTE)) + offset = offset - (unsigned long)addr; + + /* Check we can represent the target in the instruction format */ + if (!is_offset_in_branch_range(offset)) + return 1; + + /* Mask out the flags and target, so they don't step on each other. */ + *instr = ppc_inst(0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC)); + + return 0; +} + +int create_cond_branch(ppc_inst_t *instr, const u32 *addr, + unsigned long target, int flags); +int patch_branch(u32 *addr, unsigned long target, int flags); +int patch_instruction(u32 *addr, ppc_inst_t instr); +int raw_patch_instruction(u32 *addr, ppc_inst_t instr); + +static inline unsigned long patch_site_addr(s32 *site) +{ + return (unsigned long)site + *site; +} + +static inline int patch_instruction_site(s32 *site, ppc_inst_t instr) +{ + return patch_instruction((u32 *)patch_site_addr(site), instr); +} + +static inline int patch_branch_site(s32 *site, unsigned long target, int flags) +{ + return patch_branch((u32 *)patch_site_addr(site), target, flags); +} + +static inline int modify_instruction(unsigned int *addr, unsigned int clr, + unsigned int set) +{ + return patch_instruction(addr, ppc_inst((*addr & ~clr) | set)); +} + +static inline int modify_instruction_site(s32 *site, unsigned int clr, unsigned int set) +{ + return modify_instruction((unsigned int *)patch_site_addr(site), clr, set); +} + +static inline unsigned int branch_opcode(ppc_inst_t instr) +{ + return ppc_inst_primary_opcode(instr) & 0x3F; +} + +static inline int instr_is_branch_iform(ppc_inst_t instr) +{ + return branch_opcode(instr) == 18; +} + +static inline int instr_is_branch_bform(ppc_inst_t instr) +{ + return branch_opcode(instr) == 16; +} + +int instr_is_relative_branch(ppc_inst_t instr); +int instr_is_relative_link_branch(ppc_inst_t instr); +unsigned long branch_target(const u32 *instr); +int translate_branch(ppc_inst_t *instr, const u32 *dest, const u32 *src); +bool is_conditional_branch(ppc_inst_t instr); + +#define OP_RT_RA_MASK 0xffff0000UL +#define LIS_R2 (PPC_RAW_LIS(_R2, 0)) +#define ADDIS_R2_R12 (PPC_RAW_ADDIS(_R2, _R12, 0)) +#define ADDI_R2_R2 (PPC_RAW_ADDI(_R2, _R2, 0)) + + +static inline unsigned long ppc_function_entry(void *func) +{ +#ifdef CONFIG_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(CONFIG_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. + */ + return ((struct func_desc *)func)->addr; +#else + return (unsigned long)func; +#endif +} + +static inline unsigned long ppc_global_function_entry(void *func) +{ +#ifdef CONFIG_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 CONFIG_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(CONFIG_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; +} + +/* + * 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 CONFIG_PPC64_ELF_ABI_V2 +#define R2_STACK_OFFSET 24 +#else +#define R2_STACK_OFFSET 40 +#endif + +#define PPC_INST_LD_TOC PPC_RAW_LD(_R2, _R1, R2_STACK_OFFSET) + +/* usually preceded by a mflr r0 */ +#define PPC_INST_STD_LR PPC_RAW_STD(_R0, _R1, PPC_LR_STKOFF) + +#endif /* _ASM_POWERPC_CODE_PATCHING_H */ |