diff options
Diffstat (limited to 'arch/sh/kernel/kgdb.c')
-rw-r--r-- | arch/sh/kernel/kgdb.c | 378 |
1 files changed, 378 insertions, 0 deletions
diff --git a/arch/sh/kernel/kgdb.c b/arch/sh/kernel/kgdb.c new file mode 100644 index 0000000000..e4147efa9e --- /dev/null +++ b/arch/sh/kernel/kgdb.c @@ -0,0 +1,378 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * SuperH KGDB support + * + * Copyright (C) 2008 - 2012 Paul Mundt + * + * Single stepping taken from the old stub by Henry Bell and Jeremy Siegel. + */ +#include <linux/kgdb.h> +#include <linux/kdebug.h> +#include <linux/irq.h> +#include <linux/io.h> +#include <linux/sched.h> +#include <linux/sched/task_stack.h> + +#include <asm/cacheflush.h> +#include <asm/traps.h> + +/* Macros for single step instruction identification */ +#define OPCODE_BT(op) (((op) & 0xff00) == 0x8900) +#define OPCODE_BF(op) (((op) & 0xff00) == 0x8b00) +#define OPCODE_BTF_DISP(op) (((op) & 0x80) ? (((op) | 0xffffff80) << 1) : \ + (((op) & 0x7f ) << 1)) +#define OPCODE_BFS(op) (((op) & 0xff00) == 0x8f00) +#define OPCODE_BTS(op) (((op) & 0xff00) == 0x8d00) +#define OPCODE_BRA(op) (((op) & 0xf000) == 0xa000) +#define OPCODE_BRA_DISP(op) (((op) & 0x800) ? (((op) | 0xfffff800) << 1) : \ + (((op) & 0x7ff) << 1)) +#define OPCODE_BRAF(op) (((op) & 0xf0ff) == 0x0023) +#define OPCODE_BRAF_REG(op) (((op) & 0x0f00) >> 8) +#define OPCODE_BSR(op) (((op) & 0xf000) == 0xb000) +#define OPCODE_BSR_DISP(op) (((op) & 0x800) ? (((op) | 0xfffff800) << 1) : \ + (((op) & 0x7ff) << 1)) +#define OPCODE_BSRF(op) (((op) & 0xf0ff) == 0x0003) +#define OPCODE_BSRF_REG(op) (((op) >> 8) & 0xf) +#define OPCODE_JMP(op) (((op) & 0xf0ff) == 0x402b) +#define OPCODE_JMP_REG(op) (((op) >> 8) & 0xf) +#define OPCODE_JSR(op) (((op) & 0xf0ff) == 0x400b) +#define OPCODE_JSR_REG(op) (((op) >> 8) & 0xf) +#define OPCODE_RTS(op) ((op) == 0xb) +#define OPCODE_RTE(op) ((op) == 0x2b) + +#define SR_T_BIT_MASK 0x1 +#define STEP_OPCODE 0xc33d + +/* Calculate the new address for after a step */ +static short *get_step_address(struct pt_regs *linux_regs) +{ + insn_size_t op = __raw_readw(linux_regs->pc); + long addr; + + /* BT */ + if (OPCODE_BT(op)) { + if (linux_regs->sr & SR_T_BIT_MASK) + addr = linux_regs->pc + 4 + OPCODE_BTF_DISP(op); + else + addr = linux_regs->pc + 2; + } + + /* BTS */ + else if (OPCODE_BTS(op)) { + if (linux_regs->sr & SR_T_BIT_MASK) + addr = linux_regs->pc + 4 + OPCODE_BTF_DISP(op); + else + addr = linux_regs->pc + 4; /* Not in delay slot */ + } + + /* BF */ + else if (OPCODE_BF(op)) { + if (!(linux_regs->sr & SR_T_BIT_MASK)) + addr = linux_regs->pc + 4 + OPCODE_BTF_DISP(op); + else + addr = linux_regs->pc + 2; + } + + /* BFS */ + else if (OPCODE_BFS(op)) { + if (!(linux_regs->sr & SR_T_BIT_MASK)) + addr = linux_regs->pc + 4 + OPCODE_BTF_DISP(op); + else + addr = linux_regs->pc + 4; /* Not in delay slot */ + } + + /* BRA */ + else if (OPCODE_BRA(op)) + addr = linux_regs->pc + 4 + OPCODE_BRA_DISP(op); + + /* BRAF */ + else if (OPCODE_BRAF(op)) + addr = linux_regs->pc + 4 + + linux_regs->regs[OPCODE_BRAF_REG(op)]; + + /* BSR */ + else if (OPCODE_BSR(op)) + addr = linux_regs->pc + 4 + OPCODE_BSR_DISP(op); + + /* BSRF */ + else if (OPCODE_BSRF(op)) + addr = linux_regs->pc + 4 + + linux_regs->regs[OPCODE_BSRF_REG(op)]; + + /* JMP */ + else if (OPCODE_JMP(op)) + addr = linux_regs->regs[OPCODE_JMP_REG(op)]; + + /* JSR */ + else if (OPCODE_JSR(op)) + addr = linux_regs->regs[OPCODE_JSR_REG(op)]; + + /* RTS */ + else if (OPCODE_RTS(op)) + addr = linux_regs->pr; + + /* RTE */ + else if (OPCODE_RTE(op)) + addr = linux_regs->regs[15]; + + /* Other */ + else + addr = linux_regs->pc + instruction_size(op); + + flush_icache_range(addr, addr + instruction_size(op)); + return (short *)addr; +} + +/* + * Replace the instruction immediately after the current instruction + * (i.e. next in the expected flow of control) with a trap instruction, + * so that returning will cause only a single instruction to be executed. + * Note that this model is slightly broken for instructions with delay + * slots (e.g. B[TF]S, BSR, BRA etc), where both the branch and the + * instruction in the delay slot will be executed. + */ + +static unsigned long stepped_address; +static insn_size_t stepped_opcode; + +static void do_single_step(struct pt_regs *linux_regs) +{ + /* Determine where the target instruction will send us to */ + unsigned short *addr = get_step_address(linux_regs); + + stepped_address = (int)addr; + + /* Replace it */ + stepped_opcode = __raw_readw((long)addr); + *addr = STEP_OPCODE; + + /* Flush and return */ + flush_icache_range((long)addr, (long)addr + + instruction_size(stepped_opcode)); +} + +/* Undo a single step */ +static void undo_single_step(struct pt_regs *linux_regs) +{ + /* If we have stepped, put back the old instruction */ + /* Use stepped_address in case we stopped elsewhere */ + if (stepped_opcode != 0) { + __raw_writew(stepped_opcode, stepped_address); + flush_icache_range(stepped_address, stepped_address + 2); + } + + stepped_opcode = 0; +} + +struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = { + { "r0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[0]) }, + { "r1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[1]) }, + { "r2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[2]) }, + { "r3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[3]) }, + { "r4", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[4]) }, + { "r5", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[5]) }, + { "r6", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[6]) }, + { "r7", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[7]) }, + { "r8", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[8]) }, + { "r9", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[9]) }, + { "r10", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[10]) }, + { "r11", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[11]) }, + { "r12", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[12]) }, + { "r13", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[13]) }, + { "r14", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[14]) }, + { "r15", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[15]) }, + { "pc", GDB_SIZEOF_REG, offsetof(struct pt_regs, pc) }, + { "pr", GDB_SIZEOF_REG, offsetof(struct pt_regs, pr) }, + { "sr", GDB_SIZEOF_REG, offsetof(struct pt_regs, sr) }, + { "gbr", GDB_SIZEOF_REG, offsetof(struct pt_regs, gbr) }, + { "mach", GDB_SIZEOF_REG, offsetof(struct pt_regs, mach) }, + { "macl", GDB_SIZEOF_REG, offsetof(struct pt_regs, macl) }, + { "vbr", GDB_SIZEOF_REG, -1 }, +}; + +int dbg_set_reg(int regno, void *mem, struct pt_regs *regs) +{ + if (regno < 0 || regno >= DBG_MAX_REG_NUM) + return -EINVAL; + + if (dbg_reg_def[regno].offset != -1) + memcpy((void *)regs + dbg_reg_def[regno].offset, mem, + dbg_reg_def[regno].size); + + return 0; +} + +char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs) +{ + if (regno >= DBG_MAX_REG_NUM || regno < 0) + return NULL; + + if (dbg_reg_def[regno].size != -1) + memcpy(mem, (void *)regs + dbg_reg_def[regno].offset, + dbg_reg_def[regno].size); + + switch (regno) { + case GDB_VBR: + __asm__ __volatile__ ("stc vbr, %0" : "=r" (mem)); + break; + } + + return dbg_reg_def[regno].name; +} + +void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p) +{ + struct pt_regs *thread_regs = task_pt_regs(p); + int reg; + + /* Initialize to zero */ + for (reg = 0; reg < DBG_MAX_REG_NUM; reg++) + gdb_regs[reg] = 0; + + /* + * Copy out GP regs 8 to 14. + * + * switch_to() relies on SR.RB toggling, so regs 0->7 are banked + * and need privileged instructions to get to. The r15 value we + * fetch from the thread info directly. + */ + for (reg = GDB_R8; reg < GDB_R15; reg++) + gdb_regs[reg] = thread_regs->regs[reg]; + + gdb_regs[GDB_R15] = p->thread.sp; + gdb_regs[GDB_PC] = p->thread.pc; + + /* + * Additional registers we have context for + */ + gdb_regs[GDB_PR] = thread_regs->pr; + gdb_regs[GDB_GBR] = thread_regs->gbr; +} + +int kgdb_arch_handle_exception(int e_vector, int signo, int err_code, + char *remcomInBuffer, char *remcomOutBuffer, + struct pt_regs *linux_regs) +{ + unsigned long addr; + char *ptr; + + /* Undo any stepping we may have done */ + undo_single_step(linux_regs); + + switch (remcomInBuffer[0]) { + case 'c': + case 's': + /* try to read optional parameter, pc unchanged if no parm */ + ptr = &remcomInBuffer[1]; + if (kgdb_hex2long(&ptr, &addr)) + linux_regs->pc = addr; + fallthrough; + case 'D': + case 'k': + atomic_set(&kgdb_cpu_doing_single_step, -1); + + if (remcomInBuffer[0] == 's') { + do_single_step(linux_regs); + kgdb_single_step = 1; + + atomic_set(&kgdb_cpu_doing_single_step, + raw_smp_processor_id()); + } + + return 0; + } + + /* this means that we do not want to exit from the handler: */ + return -1; +} + +unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs) +{ + if (exception == 60) + return instruction_pointer(regs) - 2; + return instruction_pointer(regs); +} + +void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip) +{ + regs->pc = ip; +} + +/* + * The primary entry points for the kgdb debug trap table entries. + */ +BUILD_TRAP_HANDLER(singlestep) +{ + unsigned long flags; + TRAP_HANDLER_DECL; + + local_irq_save(flags); + regs->pc -= instruction_size(__raw_readw(regs->pc - 4)); + kgdb_handle_exception(0, SIGTRAP, 0, regs); + local_irq_restore(flags); +} + +static int __kgdb_notify(struct die_args *args, unsigned long cmd) +{ + int ret; + + switch (cmd) { + case DIE_BREAKPOINT: + /* + * This means a user thread is single stepping + * a system call which should be ignored + */ + if (test_thread_flag(TIF_SINGLESTEP)) + return NOTIFY_DONE; + + ret = kgdb_handle_exception(args->trapnr & 0xff, args->signr, + args->err, args->regs); + if (ret) + return NOTIFY_DONE; + + break; + } + + return NOTIFY_STOP; +} + +static int +kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr) +{ + unsigned long flags; + int ret; + + local_irq_save(flags); + ret = __kgdb_notify(ptr, cmd); + local_irq_restore(flags); + + return ret; +} + +static struct notifier_block kgdb_notifier = { + .notifier_call = kgdb_notify, + + /* + * Lowest-prio notifier priority, we want to be notified last: + */ + .priority = -INT_MAX, +}; + +int kgdb_arch_init(void) +{ + return register_die_notifier(&kgdb_notifier); +} + +void kgdb_arch_exit(void) +{ + unregister_die_notifier(&kgdb_notifier); +} + +const struct kgdb_arch arch_kgdb_ops = { + /* Breakpoint instruction: trapa #0x3c */ +#ifdef CONFIG_CPU_LITTLE_ENDIAN + .gdb_bpt_instr = { 0x3c, 0xc3 }, +#else + .gdb_bpt_instr = { 0xc3, 0x3c }, +#endif +}; |