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Subject[PATCH RFCv3 07/14] arm64: introduce aarch64_insn_gen_bitfield()
Date
Introduce function to generate bitfield instructions.

Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
---
arch/arm64/include/asm/insn.h | 16 +++++++++++++
arch/arm64/kernel/insn.c | 56 +++++++++++++++++++++++++++++++++++++++++++
2 files changed, 72 insertions(+)

diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h
index 29386aa..8fd31fc 100644
--- a/arch/arm64/include/asm/insn.h
+++ b/arch/arm64/include/asm/insn.h
@@ -67,6 +67,8 @@ enum aarch64_insn_imm_type {
AARCH64_INSN_IMM_12,
AARCH64_INSN_IMM_9,
AARCH64_INSN_IMM_7,
+ AARCH64_INSN_IMM_S,
+ AARCH64_INSN_IMM_R,
AARCH64_INSN_IMM_MAX
};

@@ -170,6 +172,12 @@ enum aarch64_insn_adsb_type {
AARCH64_INSN_ADSB_SUB_SETFLAGS
};

+enum aarch64_insn_bitfield_type {
+ AARCH64_INSN_BITFIELD_MOVE,
+ AARCH64_INSN_BITFIELD_MOVE_UNSIGNED,
+ AARCH64_INSN_BITFIELD_MOVE_SIGNED
+};
+
#define __AARCH64_INSN_FUNCS(abbr, mask, val) \
static __always_inline bool aarch64_insn_is_##abbr(u32 code) \
{ return (code & (mask)) == (val); } \
@@ -186,6 +194,9 @@ __AARCH64_INSN_FUNCS(add_imm, 0x7F000000, 0x11000000)
__AARCH64_INSN_FUNCS(adds_imm, 0x7F000000, 0x31000000)
__AARCH64_INSN_FUNCS(sub_imm, 0x7F000000, 0x51000000)
__AARCH64_INSN_FUNCS(subs_imm, 0x7F000000, 0x71000000)
+__AARCH64_INSN_FUNCS(sbfm, 0x7F800000, 0x13000000)
+__AARCH64_INSN_FUNCS(bfm, 0x7F800000, 0x33000000)
+__AARCH64_INSN_FUNCS(ubfm, 0x7F800000, 0x53000000)
__AARCH64_INSN_FUNCS(b, 0xFC000000, 0x14000000)
__AARCH64_INSN_FUNCS(bl, 0xFC000000, 0x94000000)
__AARCH64_INSN_FUNCS(cbz, 0xFE000000, 0x34000000)
@@ -236,6 +247,11 @@ u32 aarch64_insn_gen_add_sub_imm(enum aarch64_insn_register dst,
enum aarch64_insn_register src,
int imm, enum aarch64_insn_variant variant,
enum aarch64_insn_adsb_type type);
+u32 aarch64_insn_gen_bitfield(enum aarch64_insn_register dst,
+ enum aarch64_insn_register src,
+ int immr, int imms,
+ enum aarch64_insn_variant variant,
+ enum aarch64_insn_bitfield_type type);

bool aarch64_insn_hotpatch_safe(u32 old_insn, u32 new_insn);

diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c
index e11acb7..01ed35c 100644
--- a/arch/arm64/kernel/insn.c
+++ b/arch/arm64/kernel/insn.c
@@ -257,6 +257,14 @@ u32 __kprobes aarch64_insn_encode_immediate(enum aarch64_insn_imm_type type,
mask = BIT(7) - 1;
shift = 15;
break;
+ case AARCH64_INSN_IMM_S:
+ mask = BIT(6) - 1;
+ shift = 10;
+ break;
+ case AARCH64_INSN_IMM_R:
+ mask = BIT(6) - 1;
+ shift = 16;
+ break;
default:
pr_err("aarch64_insn_encode_immediate: unknown immediate encoding %d\n",
type);
@@ -597,3 +605,51 @@ u32 aarch64_insn_gen_add_sub_imm(enum aarch64_insn_register dst,

return aarch64_insn_encode_immediate(AARCH64_INSN_IMM_12, insn, imm);
}
+
+u32 aarch64_insn_gen_bitfield(enum aarch64_insn_register dst,
+ enum aarch64_insn_register src,
+ int immr, int imms,
+ enum aarch64_insn_variant variant,
+ enum aarch64_insn_bitfield_type type)
+{
+ u32 insn;
+ u32 mask;
+
+ switch (type) {
+ case AARCH64_INSN_BITFIELD_MOVE:
+ insn = aarch64_insn_get_bfm_value();
+ break;
+ case AARCH64_INSN_BITFIELD_MOVE_UNSIGNED:
+ insn = aarch64_insn_get_ubfm_value();
+ break;
+ case AARCH64_INSN_BITFIELD_MOVE_SIGNED:
+ insn = aarch64_insn_get_sbfm_value();
+ break;
+ default:
+ BUG_ON(1);
+ }
+
+ switch (variant) {
+ case AARCH64_INSN_VARIANT_32BIT:
+ mask = GENMASK(4, 0);
+ break;
+ case AARCH64_INSN_VARIANT_64BIT:
+ insn |= BIT(31);
+ insn |= BIT(22);
+ mask = GENMASK(5, 0);
+ break;
+ default:
+ BUG_ON(1);
+ }
+
+ BUG_ON(immr & ~mask);
+ BUG_ON(imms & ~mask);
+
+ insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RD, insn, dst);
+
+ insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RN, insn, src);
+
+ insn = aarch64_insn_encode_immediate(AARCH64_INSN_IMM_R, insn, immr);
+
+ return aarch64_insn_encode_immediate(AARCH64_INSN_IMM_S, insn, imms);
+}
--
1.9.1


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