arm64: introduce aarch64_insn_gen_bitfield()

Introduce function to generate bitfield instructions.

Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

2 files changed, 72 insertions, 0 deletions

diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h
index 29386aaf2e85..8fd31fc29c47 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 ec3a90256ff9..e07d026e75d8 100644
--- a/arch/arm64/kernel/insn.c
+++ b/arch/arm64/kernel/insn.c
@@ -26,6 +26,7 @@
 #include <asm/insn.h>
 
 #define AARCH64_INSN_SF_BIT     BIT(31)
+#define AARCH64_INSN_N_BIT      BIT(22)
 
 static int aarch64_insn_encoding_class[] = {
         AARCH64_INSN_CLS_UNKNOWN,
@@ -259,6 +260,14 @@ 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);
@@ -599,3 +608,50 @@ 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 |= AARCH64_INSN_SF_BIT | AARCH64_INSN_N_BIT;
+                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);
+}