diff options
Diffstat (limited to 'arch/powerpc/include/asm/code-patching.h')
| -rw-r--r-- | arch/powerpc/include/asm/code-patching.h | 29 |
1 files changed, 27 insertions, 2 deletions
diff --git a/arch/powerpc/include/asm/code-patching.h b/arch/powerpc/include/asm/code-patching.h index bccc3a538b9f..378b70545a32 100644 --- a/arch/powerpc/include/asm/code-patching.h +++ b/arch/powerpc/include/asm/code-patching.h @@ -24,8 +24,33 @@ DECLARE_STATIC_KEY_FALSE(init_mem_is_free); -bool is_offset_in_branch_range(long offset); -bool is_offset_in_cond_branch_range(long offset); +/* + * 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); +} + int create_branch(ppc_inst_t *instr, const u32 *addr, unsigned long target, int flags); int create_cond_branch(ppc_inst_t *instr, const u32 *addr, |