[PATCH 4/8] arm64/insn: Add helpers for pc relative address offsets

[Suzuki K Poulose]

Adds helpers for decoding/encoding the PC relative addresses for
Data processing instructions (i.e, adr and adrp). This will be used
for handling dynamic patching of 'adr/adrp' instructions in alternative
code patching.

Cc: Mark Rutland <mark.rutl...@arm.com>
Cc: Will Deacon <will.dea...@arm.com>
Cc: Catalin Marinas <catalin.mari...@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poul...@arm.com>
---
 arch/arm64/include/asm/insn.h |  5 +++++
 arch/arm64/kernel/insn.c      | 23 +++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h
index 30e50eb..03dc4c2 100644
--- a/arch/arm64/include/asm/insn.h
+++ b/arch/arm64/include/asm/insn.h
@@ -277,6 +277,8 @@ __AARCH64_INSN_FUNCS(hint,  0xFFFFF01F, 0xD503201F)
 __AARCH64_INSN_FUNCS(br,       0xFFFFFC1F, 0xD61F0000)
 __AARCH64_INSN_FUNCS(blr,      0xFFFFFC1F, 0xD63F0000)
 __AARCH64_INSN_FUNCS(ret,      0xFFFFFC1F, 0xD65F0000)
+__AARCH64_INSN_FUNCS(adrp,     0x9F000000, 0x90000000)
+__AARCH64_INSN_FUNCS(adr,      0x9F000000, 0x10000000)
 
 #undef __AARCH64_INSN_FUNCS
 
@@ -355,6 +357,9 @@ u32 aarch64_insn_gen_logical_shifted_reg(enum 
aarch64_insn_register dst,
 s32 aarch64_get_branch_offset(u32 insn);
 u32 aarch64_set_branch_offset(u32 insn, s32 offset);
 
+s32 aarch64_get_addr_offset(u32 insn);
+u32 aarch64_set_addr_offset(u32 insn, s32 offset);
+
 bool aarch64_insn_hotpatch_safe(u32 old_insn, u32 new_insn);
 
 int aarch64_insn_patch_text_nosync(void *addr, u32 insn);
diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c
index 368c082..3edd741 100644
--- a/arch/arm64/kernel/insn.c
+++ b/arch/arm64/kernel/insn.c
@@ -1175,6 +1175,29 @@ u32 aarch64_set_branch_offset(u32 insn, s32 offset)
        BUG();
 }
 
+s32 aarch64_get_addr_offset(u32 insn)
+{
+       if (aarch64_insn_is_adr(insn))
+               return aarch64_insn_decode_immediate(AARCH64_INSN_IMM_ADR, 
insn);
+       if (aarch64_insn_is_adrp(insn))
+               return aarch64_insn_decode_immediate(AARCH64_INSN_IMM_ADR, 
insn) << 12;
+
+       /* Unhandled instruction */
+       BUG();
+}
+
+u32 aarch64_set_addr_offset(u32 insn, s32 offset)
+{
+       if (aarch64_insn_is_adr(insn))
+               return aarch64_insn_encode_immediate(AARCH64_INSN_IMM_ADR, insn,
+                                                                       offset);
+       if (aarch64_insn_is_adrp(insn))
+               return aarch64_insn_encode_immediate(AARCH64_INSN_IMM_ADR, insn,
+                                                                       offset 
>> 12);
+       /* Unhandled instruction */
+       BUG();
+}
+
 bool aarch32_insn_is_wide(u32 insn)
 {
        return insn >= 0xe800;
-- 
2.7.4