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-rw-r--r--arch/riscv/kernel/kgdb.c179
1 files changed, 177 insertions, 2 deletions
diff --git a/arch/riscv/kernel/kgdb.c b/arch/riscv/kernel/kgdb.c
index eb1afab47679..f16ade84a11f 100644
--- a/arch/riscv/kernel/kgdb.c
+++ b/arch/riscv/kernel/kgdb.c
@@ -11,13 +11,179 @@
#include <linux/string.h>
#include <asm/cacheflush.h>
#include <asm/gdb_xml.h>
+#include <asm/parse_asm.h>
enum {
NOT_KGDB_BREAK = 0,
KGDB_SW_BREAK,
KGDB_COMPILED_BREAK,
+ KGDB_SW_SINGLE_STEP
};
+static unsigned long stepped_address;
+static unsigned int stepped_opcode;
+
+#if __riscv_xlen == 32
+/* C.JAL is an RV32C-only instruction */
+DECLARE_INSN(c_jal, MATCH_C_JAL, MASK_C_JAL)
+#else
+#define is_c_jal_insn(opcode) 0
+#endif
+DECLARE_INSN(jalr, MATCH_JALR, MASK_JALR)
+DECLARE_INSN(jal, MATCH_JAL, MASK_JAL)
+DECLARE_INSN(c_jr, MATCH_C_JR, MASK_C_JR)
+DECLARE_INSN(c_jalr, MATCH_C_JALR, MASK_C_JALR)
+DECLARE_INSN(c_j, MATCH_C_J, MASK_C_J)
+DECLARE_INSN(beq, MATCH_BEQ, MASK_BEQ)
+DECLARE_INSN(bne, MATCH_BNE, MASK_BNE)
+DECLARE_INSN(blt, MATCH_BLT, MASK_BLT)
+DECLARE_INSN(bge, MATCH_BGE, MASK_BGE)
+DECLARE_INSN(bltu, MATCH_BLTU, MASK_BLTU)
+DECLARE_INSN(bgeu, MATCH_BGEU, MASK_BGEU)
+DECLARE_INSN(c_beqz, MATCH_C_BEQZ, MASK_C_BEQZ)
+DECLARE_INSN(c_bnez, MATCH_C_BNEZ, MASK_C_BNEZ)
+DECLARE_INSN(sret, MATCH_SRET, MASK_SRET)
+
+int decode_register_index(unsigned long opcode, int offset)
+{
+ return (opcode >> offset) & 0x1F;
+}
+
+int decode_register_index_short(unsigned long opcode, int offset)
+{
+ return ((opcode >> offset) & 0x7) + 8;
+}
+
+/* Calculate the new address for after a step */
+int get_step_address(struct pt_regs *regs, unsigned long *next_addr)
+{
+ unsigned long pc = regs->epc;
+ unsigned long *regs_ptr = (unsigned long *)regs;
+ unsigned int rs1_num, rs2_num;
+ int op_code;
+
+ if (probe_kernel_address((void *)pc, op_code))
+ return -EINVAL;
+ if ((op_code & __INSN_LENGTH_MASK) != __INSN_LENGTH_GE_32) {
+ if (is_c_jalr_insn(op_code) || is_c_jr_insn(op_code)) {
+ rs1_num = decode_register_index(op_code, RVC_C2_RS1_OPOFF);
+ *next_addr = regs_ptr[rs1_num];
+ } else if (is_c_j_insn(op_code) || is_c_jal_insn(op_code)) {
+ *next_addr = EXTRACT_RVC_J_IMM(op_code) + pc;
+ } else if (is_c_beqz_insn(op_code)) {
+ rs1_num = decode_register_index_short(op_code,
+ RVC_C1_RS1_OPOFF);
+ if (!rs1_num || regs_ptr[rs1_num] == 0)
+ *next_addr = EXTRACT_RVC_B_IMM(op_code) + pc;
+ else
+ *next_addr = pc + 2;
+ } else if (is_c_bnez_insn(op_code)) {
+ rs1_num =
+ decode_register_index_short(op_code, RVC_C1_RS1_OPOFF);
+ if (rs1_num && regs_ptr[rs1_num] != 0)
+ *next_addr = EXTRACT_RVC_B_IMM(op_code) + pc;
+ else
+ *next_addr = pc + 2;
+ } else {
+ *next_addr = pc + 2;
+ }
+ } else {
+ if ((op_code & __INSN_OPCODE_MASK) == __INSN_BRANCH_OPCODE) {
+ bool result = false;
+ long imm = EXTRACT_BTYPE_IMM(op_code);
+ unsigned long rs1_val = 0, rs2_val = 0;
+
+ rs1_num = decode_register_index(op_code, RVG_RS1_OPOFF);
+ rs2_num = decode_register_index(op_code, RVG_RS2_OPOFF);
+ if (rs1_num)
+ rs1_val = regs_ptr[rs1_num];
+ if (rs2_num)
+ rs2_val = regs_ptr[rs2_num];
+
+ if (is_beq_insn(op_code))
+ result = (rs1_val == rs2_val) ? true : false;
+ else if (is_bne_insn(op_code))
+ result = (rs1_val != rs2_val) ? true : false;
+ else if (is_blt_insn(op_code))
+ result =
+ ((long)rs1_val <
+ (long)rs2_val) ? true : false;
+ else if (is_bge_insn(op_code))
+ result =
+ ((long)rs1_val >=
+ (long)rs2_val) ? true : false;
+ else if (is_bltu_insn(op_code))
+ result = (rs1_val < rs2_val) ? true : false;
+ else if (is_bgeu_insn(op_code))
+ result = (rs1_val >= rs2_val) ? true : false;
+ if (result)
+ *next_addr = imm + pc;
+ else
+ *next_addr = pc + 4;
+ } else if (is_jal_insn(op_code)) {
+ *next_addr = EXTRACT_JTYPE_IMM(op_code) + pc;
+ } else if (is_jalr_insn(op_code)) {
+ rs1_num = decode_register_index(op_code, RVG_RS1_OPOFF);
+ if (rs1_num)
+ *next_addr = ((unsigned long *)regs)[rs1_num];
+ *next_addr += EXTRACT_ITYPE_IMM(op_code);
+ } else if (is_sret_insn(op_code)) {
+ *next_addr = pc;
+ } else {
+ *next_addr = pc + 4;
+ }
+ }
+ return 0;
+}
+
+int do_single_step(struct pt_regs *regs)
+{
+ /* Determine where the target instruction will send us to */
+ unsigned long addr = 0;
+ int error = get_step_address(regs, &addr);
+
+ if (error)
+ return error;
+
+ /* Store the op code in the stepped address */
+ error = probe_kernel_address((void *)addr, stepped_opcode);
+ if (error)
+ return error;
+
+ stepped_address = addr;
+
+ /* Replace the op code with the break instruction */
+ error = probe_kernel_write((void *)stepped_address,
+ arch_kgdb_ops.gdb_bpt_instr,
+ BREAK_INSTR_SIZE);
+ /* Flush and return */
+ if (!error) {
+ flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
+ kgdb_single_step = 1;
+ atomic_set(&kgdb_cpu_doing_single_step,
+ raw_smp_processor_id());
+ } else {
+ stepped_address = 0;
+ stepped_opcode = 0;
+ }
+ return error;
+}
+
+/* Undo a single step */
+static void undo_single_step(struct pt_regs *regs)
+{
+ if (stepped_opcode != 0) {
+ probe_kernel_write((void *)stepped_address,
+ (void *)&stepped_opcode, BREAK_INSTR_SIZE);
+ flush_icache_range(stepped_address,
+ stepped_address + BREAK_INSTR_SIZE);
+ }
+ stepped_address = 0;
+ stepped_opcode = 0;
+ kgdb_single_step = 0;
+ atomic_set(&kgdb_cpu_doing_single_step, -1);
+}
+
struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = {
{DBG_REG_ZERO, GDB_SIZEOF_REG, -1},
{DBG_REG_RA, GDB_SIZEOF_REG, offsetof(struct pt_regs, ra)},
@@ -135,6 +301,8 @@ int kgdb_arch_handle_exception(int vector, int signo, int err_code,
{
int err = 0;
+ undo_single_step(regs);
+
switch (remcom_in_buffer[0]) {
case 'c':
case 'D':
@@ -142,15 +310,20 @@ int kgdb_arch_handle_exception(int vector, int signo, int err_code,
if (remcom_in_buffer[0] == 'c')
kgdb_arch_update_addr(regs, remcom_in_buffer);
break;
+ case 's':
+ kgdb_arch_update_addr(regs, remcom_in_buffer);
+ err = do_single_step(regs);
+ break;
default:
err = -1;
}
-
return err;
}
int kgdb_riscv_kgdbbreak(unsigned long addr)
{
+ if (stepped_address == addr)
+ return KGDB_SW_SINGLE_STEP;
if (atomic_read(&kgdb_setting_breakpoint))
if (addr == (unsigned long)&kgdb_compiled_break)
return KGDB_COMPILED_BREAK;
@@ -174,7 +347,9 @@ static int kgdb_riscv_notify(struct notifier_block *self, unsigned long cmd,
return NOTIFY_DONE;
local_irq_save(flags);
- if (kgdb_handle_exception(1, args->signr, cmd, regs))
+
+ if (kgdb_handle_exception(type == KGDB_SW_SINGLE_STEP ? 0 : 1,
+ args->signr, cmd, regs))
return NOTIFY_DONE;
if (type == KGDB_COMPILED_BREAK)
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-12 01:58:19 +0000