diff options
Diffstat (limited to 'arch/arm64/include/asm/module.h')
| -rw-r--r-- | arch/arm64/include/asm/module.h | 46 |
1 files changed, 45 insertions, 1 deletions
diff --git a/arch/arm64/include/asm/module.h b/arch/arm64/include/asm/module.h index 19bd97671bb8..4f766178fa6f 100644 --- a/arch/arm64/include/asm/module.h +++ b/arch/arm64/include/asm/module.h @@ -32,7 +32,7 @@ struct mod_arch_specific { struct mod_plt_sec init; /* for CONFIG_DYNAMIC_FTRACE */ - void *ftrace_trampoline; + struct plt_entry *ftrace_trampoline; }; #endif @@ -45,4 +45,48 @@ extern u64 module_alloc_base; #define module_alloc_base ((u64)_etext - MODULES_VSIZE) #endif +struct plt_entry { + /* + * A program that conforms to the AArch64 Procedure Call Standard + * (AAPCS64) must assume that a veneer that alters IP0 (x16) and/or + * IP1 (x17) may be inserted at any branch instruction that is + * exposed to a relocation that supports long branches. Since that + * is exactly what we are dealing with here, we are free to use x16 + * as a scratch register in the PLT veneers. + */ + __le32 mov0; /* movn x16, #0x.... */ + __le32 mov1; /* movk x16, #0x...., lsl #16 */ + __le32 mov2; /* movk x16, #0x...., lsl #32 */ + __le32 br; /* br x16 */ +}; + +static inline struct plt_entry get_plt_entry(u64 val) +{ + /* + * MOVK/MOVN/MOVZ opcode: + * +--------+------------+--------+-----------+-------------+---------+ + * | sf[31] | opc[30:29] | 100101 | hw[22:21] | imm16[20:5] | Rd[4:0] | + * +--------+------------+--------+-----------+-------------+---------+ + * + * Rd := 0x10 (x16) + * hw := 0b00 (no shift), 0b01 (lsl #16), 0b10 (lsl #32) + * opc := 0b11 (MOVK), 0b00 (MOVN), 0b10 (MOVZ) + * sf := 1 (64-bit variant) + */ + return (struct plt_entry){ + cpu_to_le32(0x92800010 | (((~val ) & 0xffff)) << 5), + cpu_to_le32(0xf2a00010 | ((( val >> 16) & 0xffff)) << 5), + cpu_to_le32(0xf2c00010 | ((( val >> 32) & 0xffff)) << 5), + cpu_to_le32(0xd61f0200) + }; +} + +static inline bool plt_entries_equal(const struct plt_entry *a, + const struct plt_entry *b) +{ + return a->mov0 == b->mov0 && + a->mov1 == b->mov1 && + a->mov2 == b->mov2; +} + #endif /* __ASM_MODULE_H */ |