[PATCH v6 04/13] riscv/kprobe: Add common RVI and RVC instruction decoder code
From: Chen Guokai
Date: Fri Jan 27 2023 - 08:06:52 EST
From: Liao Chang <liaochang1@xxxxxxxxxx>
These RVI and RVC instruction decoder are used in the free register
searching algorithm, each instruction of instrumented function needs to
decode and test if it contains a free register to form AUIPC/JALR.
For RVI instruction format, the position and length of rs1/rs2/rd/opcode
parts are uniform [1], but RVC instruction formats are complicated, so
it addresses a series of functions to decode rs1/rs2/rd for RVC [1].
[1] https://github.com/riscv/riscv-isa-manual/releases
Signed-off-by: Liao Chang <liaochang1@xxxxxxxxxx>
Co-developed-by: Chen Guokai <chenguokai17@xxxxxxxxxxxxxxxx>
Signed-off-by: Chen Guokai <chenguokai17@xxxxxxxxxxxxxxxx>
---
arch/riscv/include/asm/bug.h | 5 +-
arch/riscv/kernel/probes/decode-insn.h | 148 +++++++++++++++++++++++
arch/riscv/kernel/probes/simulate-insn.h | 42 +++++++
3 files changed, 194 insertions(+), 1 deletion(-)
diff --git a/arch/riscv/include/asm/bug.h b/arch/riscv/include/asm/bug.h
index 1aaea81fb141..9c33d3b58225 100644
--- a/arch/riscv/include/asm/bug.h
+++ b/arch/riscv/include/asm/bug.h
@@ -19,11 +19,14 @@
#define __BUG_INSN_32 _UL(0x00100073) /* ebreak */
#define __BUG_INSN_16 _UL(0x9002) /* c.ebreak */
+#define RVI_INSN_LEN 4UL
+#define RVC_INSN_LEN 2UL
+
#define GET_INSN_LENGTH(insn) \
({ \
unsigned long __len; \
__len = ((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32) ? \
- 4UL : 2UL; \
+ RVI_INSN_LEN : RVC_INSN_LEN; \
__len; \
})
diff --git a/arch/riscv/kernel/probes/decode-insn.h b/arch/riscv/kernel/probes/decode-insn.h
index 42269a7d676d..785b023a62ea 100644
--- a/arch/riscv/kernel/probes/decode-insn.h
+++ b/arch/riscv/kernel/probes/decode-insn.h
@@ -3,6 +3,7 @@
#ifndef _RISCV_KERNEL_KPROBES_DECODE_INSN_H
#define _RISCV_KERNEL_KPROBES_DECODE_INSN_H
+#include <linux/bitops.h>
#include <asm/sections.h>
#include <asm/kprobes.h>
@@ -15,4 +16,151 @@ enum probe_insn {
enum probe_insn __kprobes
riscv_probe_decode_insn(probe_opcode_t *addr, struct arch_probe_insn *asi);
+#ifdef CONFIG_KPROBES
+
+static inline u16 rvi_rs1(kprobe_opcode_t opcode)
+{
+ return (u16)((opcode >> 15) & 0x1f);
+}
+
+static inline u16 rvi_rs2(kprobe_opcode_t opcode)
+{
+ return (u16)((opcode >> 20) & 0x1f);
+}
+
+static inline u16 rvi_rd(kprobe_opcode_t opcode)
+{
+ return (u16)((opcode >> 7) & 0x1f);
+}
+
+static inline s32 rvi_branch_imme(kprobe_opcode_t opcode)
+{
+ u32 imme = 0;
+
+ imme |= (((opcode >> 8) & 0xf) << 1) |
+ (((opcode >> 25) & 0x3f) << 5) |
+ (((opcode >> 7) & 0x1) << 11) |
+ (((opcode >> 31) & 0x1) << 12);
+
+ return sign_extend32(imme, 13);
+}
+
+static inline s32 rvi_jal_imme(kprobe_opcode_t opcode)
+{
+ u32 imme = 0;
+
+ imme |= (((opcode >> 21) & 0x3ff) << 1) |
+ (((opcode >> 20) & 0x1) << 11) |
+ (((opcode >> 12) & 0xff) << 12) |
+ (((opcode >> 31) & 0x1) << 20);
+
+ return sign_extend32(imme, 21);
+}
+
+#ifdef CONFIG_RISCV_ISA_C
+static inline u16 rvc_r_rs1(kprobe_opcode_t opcode)
+{
+ return (u16)((opcode >> 2) & 0x1f);
+}
+
+static inline u16 rvc_r_rs2(kprobe_opcode_t opcode)
+{
+ return (u16)((opcode >> 2) & 0x1f);
+}
+
+static inline u16 rvc_r_rd(kprobe_opcode_t opcode)
+{
+ return rvc_r_rs1(opcode);
+}
+
+static inline u16 rvc_i_rs1(kprobe_opcode_t opcode)
+{
+ return (u16)((opcode >> 7) & 0x1f);
+}
+
+static inline u16 rvc_i_rd(kprobe_opcode_t opcode)
+{
+ return rvc_i_rs1(opcode);
+}
+
+static inline u16 rvc_ss_rs2(kprobe_opcode_t opcode)
+{
+ return (u16)((opcode >> 2) & 0x1f);
+}
+
+static inline u16 rvc_l_rd(kprobe_opcode_t opcode)
+{
+ return (u16)((opcode >> 2) & 0x7);
+}
+
+static inline u16 rvc_l_rs(kprobe_opcode_t opcode)
+{
+ return (u16)((opcode >> 7) & 0x7);
+}
+
+static inline u16 rvc_s_rs2(kprobe_opcode_t opcode)
+{
+ return (u16)((opcode >> 2) & 0x7);
+}
+
+static inline u16 rvc_s_rs1(kprobe_opcode_t opcode)
+{
+ return (u16)((opcode >> 7) & 0x7);
+}
+
+static inline u16 rvc_a_rs2(kprobe_opcode_t opcode)
+{
+ return (u16)((opcode >> 2) & 0x7);
+}
+
+static inline u16 rvc_a_rs1(kprobe_opcode_t opcode)
+{
+ return (u16)((opcode >> 7) & 0x7);
+}
+
+static inline u16 rvc_a_rd(kprobe_opcode_t opcode)
+{
+ return rvc_a_rs1(opcode);
+}
+
+static inline u16 rvc_b_rd(kprobe_opcode_t opcode)
+{
+ return (u16)((opcode >> 7) & 0x7);
+}
+
+static inline u16 rvc_b_rs(kprobe_opcode_t opcode)
+{
+ return rvc_b_rd(opcode);
+}
+
+static inline s32 rvc_branch_imme(kprobe_opcode_t opcode)
+{
+ u32 imme = 0;
+
+ imme |= (((opcode >> 3) & 0x3) << 1) |
+ (((opcode >> 10) & 0x3) << 3) |
+ (((opcode >> 2) & 0x1) << 5) |
+ (((opcode >> 5) & 0x3) << 6) |
+ (((opcode >> 12) & 0x1) << 8);
+
+ return sign_extend32(imme, 9);
+}
+
+static inline s32 rvc_jal_imme(kprobe_opcode_t opcode)
+{
+ u32 imme = 0;
+
+ imme |= (((opcode >> 3) & 0x3) << 1) |
+ (((opcode >> 11) & 0x1) << 4) |
+ (((opcode >> 2) & 0x1) << 5) |
+ (((opcode >> 7) & 0x1) << 6) |
+ (((opcode >> 6) & 0x1) << 7) |
+ (((opcode >> 9) & 0x3) << 8) |
+ (((opcode >> 8) & 0x1) << 10) |
+ (((opcode >> 12) & 0x1) << 11);
+
+ return sign_extend32(imme, 12);
+}
+#endif /* CONFIG_KPROBES */
+#endif /* CONFIG_RISCV_ISA_C */
#endif /* _RISCV_KERNEL_KPROBES_DECODE_INSN_H */
diff --git a/arch/riscv/kernel/probes/simulate-insn.h b/arch/riscv/kernel/probes/simulate-insn.h
index a19aaa0feb44..e89747dfabbb 100644
--- a/arch/riscv/kernel/probes/simulate-insn.h
+++ b/arch/riscv/kernel/probes/simulate-insn.h
@@ -28,4 +28,46 @@ bool simulate_branch(u32 opcode, unsigned long addr, struct pt_regs *regs);
bool simulate_jal(u32 opcode, unsigned long addr, struct pt_regs *regs);
bool simulate_jalr(u32 opcode, unsigned long addr, struct pt_regs *regs);
+/* RVC(S) instructions contain rs1 and rs2 */
+__RISCV_INSN_FUNCS(c_sq, 0xe003, 0xa000);
+__RISCV_INSN_FUNCS(c_sw, 0xe003, 0xc000);
+__RISCV_INSN_FUNCS(c_sd, 0xe003, 0xe000);
+/* RVC(A) instructions contain rs1 and rs2 */
+__RISCV_INSN_FUNCS(c_sub, 0xfc63, 0x8c01);
+__RISCV_INSN_FUNCS(c_subw, 0xfc43, 0x9c01);
+/* RVC(L) instructions contain rs1 */
+__RISCV_INSN_FUNCS(c_lq, 0xe003, 0x2000);
+__RISCV_INSN_FUNCS(c_lw, 0xe003, 0x4000);
+__RISCV_INSN_FUNCS(c_ld, 0xe003, 0x6000);
+/* RVC(I) instructions contain rs1 */
+__RISCV_INSN_FUNCS(c_addi, 0xe003, 0x0001);
+__RISCV_INSN_FUNCS(c_addiw, 0xe003, 0x2001);
+__RISCV_INSN_FUNCS(c_addi16sp, 0xe183, 0x6101);
+__RISCV_INSN_FUNCS(c_slli, 0xe003, 0x0002);
+/* RVC(B) instructions contain rs1 */
+__RISCV_INSN_FUNCS(c_sri, 0xe803, 0x8001);
+__RISCV_INSN_FUNCS(c_andi, 0xec03, 0x8801);
+/* RVC(SS) instructions contain rs2 */
+__RISCV_INSN_FUNCS(c_sqsp, 0xe003, 0xa002);
+__RISCV_INSN_FUNCS(c_swsp, 0xe003, 0xc002);
+__RISCV_INSN_FUNCS(c_sdsp, 0xe003, 0xe002);
+/* RVC(R) instructions contain rs2 and rd */
+__RISCV_INSN_FUNCS(c_mv, 0xf003, 0x8002);
+/* RVC(I) instructions contain sp and rd */
+__RISCV_INSN_FUNCS(c_lqsp, 0xe003, 0x2002);
+__RISCV_INSN_FUNCS(c_lwsp, 0xe003, 0x4002);
+__RISCV_INSN_FUNCS(c_ldsp, 0xe003, 0x6002);
+/* RVC(CW) instructions contain sp and rd */
+__RISCV_INSN_FUNCS(c_addi4spn, 0xe003, 0x0000);
+/* RVC(I) instructions contain rd */
+__RISCV_INSN_FUNCS(c_li, 0xe003, 0x4001);
+__RISCV_INSN_FUNCS(c_lui, 0xe003, 0x6001);
+
+__RISCV_INSN_FUNCS(arith_rr, 0x77, 0x33);
+__RISCV_INSN_FUNCS(arith_ri, 0x77, 0x13);
+__RISCV_INSN_FUNCS(lui, 0x7f, 0x37);
+__RISCV_INSN_FUNCS(load, 0x7f, 0x03);
+__RISCV_INSN_FUNCS(store, 0x7f, 0x23);
+__RISCV_INSN_FUNCS(amo, 0x7f, 0x2f);
+
#endif /* _RISCV_KERNEL_PROBES_SIMULATE_INSN_H */
--
2.34.1