diff options
Diffstat (limited to 'arch/arc/kernel/kgdb.c')
| -rw-r--r-- | arch/arc/kernel/kgdb.c | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/arch/arc/kernel/kgdb.c b/arch/arc/kernel/kgdb.c new file mode 100644 index 000000000..345a00005 --- /dev/null +++ b/arch/arc/kernel/kgdb.c @@ -0,0 +1,206 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * kgdb support for ARC + * + * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.com) + */ + +#include <linux/kgdb.h> +#include <linux/sched.h> +#include <linux/sched/task_stack.h> +#include <asm/disasm.h> +#include <asm/cacheflush.h> + +static void to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs, + struct callee_regs *cregs) +{ + int regno; + + for (regno = 0; regno <= 26; regno++) + gdb_regs[_R0 + regno] = get_reg(regno, kernel_regs, cregs); + + for (regno = 27; regno < GDB_MAX_REGS; regno++) + gdb_regs[regno] = 0; + + gdb_regs[_FP] = kernel_regs->fp; + gdb_regs[__SP] = kernel_regs->sp; + gdb_regs[_BLINK] = kernel_regs->blink; + gdb_regs[_RET] = kernel_regs->ret; + gdb_regs[_STATUS32] = kernel_regs->status32; + gdb_regs[_LP_COUNT] = kernel_regs->lp_count; + gdb_regs[_LP_END] = kernel_regs->lp_end; + gdb_regs[_LP_START] = kernel_regs->lp_start; + gdb_regs[_BTA] = kernel_regs->bta; + gdb_regs[_STOP_PC] = kernel_regs->ret; +} + +static void from_gdb_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs, + struct callee_regs *cregs) +{ + int regno; + + for (regno = 0; regno <= 26; regno++) + set_reg(regno, gdb_regs[regno + _R0], kernel_regs, cregs); + + kernel_regs->fp = gdb_regs[_FP]; + kernel_regs->sp = gdb_regs[__SP]; + kernel_regs->blink = gdb_regs[_BLINK]; + kernel_regs->ret = gdb_regs[_RET]; + kernel_regs->status32 = gdb_regs[_STATUS32]; + kernel_regs->lp_count = gdb_regs[_LP_COUNT]; + kernel_regs->lp_end = gdb_regs[_LP_END]; + kernel_regs->lp_start = gdb_regs[_LP_START]; + kernel_regs->bta = gdb_regs[_BTA]; +} + + +void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs) +{ + to_gdb_regs(gdb_regs, kernel_regs, (struct callee_regs *) + current->thread.callee_reg); +} + +void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs) +{ + from_gdb_regs(gdb_regs, kernel_regs, (struct callee_regs *) + current->thread.callee_reg); +} + +void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, + struct task_struct *task) +{ + if (task) + to_gdb_regs(gdb_regs, task_pt_regs(task), + (struct callee_regs *) task->thread.callee_reg); +} + +struct single_step_data_t { + uint16_t opcode[2]; + unsigned long address[2]; + int is_branch; + int armed; +} single_step_data; + +static void undo_single_step(struct pt_regs *regs) +{ + if (single_step_data.armed) { + int i; + + for (i = 0; i < (single_step_data.is_branch ? 2 : 1); i++) { + memcpy((void *) single_step_data.address[i], + &single_step_data.opcode[i], + BREAK_INSTR_SIZE); + + flush_icache_range(single_step_data.address[i], + single_step_data.address[i] + + BREAK_INSTR_SIZE); + } + single_step_data.armed = 0; + } +} + +static void place_trap(unsigned long address, void *save) +{ + memcpy(save, (void *) address, BREAK_INSTR_SIZE); + memcpy((void *) address, &arch_kgdb_ops.gdb_bpt_instr, + BREAK_INSTR_SIZE); + flush_icache_range(address, address + BREAK_INSTR_SIZE); +} + +static void do_single_step(struct pt_regs *regs) +{ + single_step_data.is_branch = disasm_next_pc((unsigned long) + regs->ret, regs, (struct callee_regs *) + current->thread.callee_reg, + &single_step_data.address[0], + &single_step_data.address[1]); + + place_trap(single_step_data.address[0], &single_step_data.opcode[0]); + + if (single_step_data.is_branch) { + place_trap(single_step_data.address[1], + &single_step_data.opcode[1]); + } + + single_step_data.armed++; +} + +int kgdb_arch_handle_exception(int e_vector, int signo, int err_code, + char *remcomInBuffer, char *remcomOutBuffer, + struct pt_regs *regs) +{ + unsigned long addr; + char *ptr; + + undo_single_step(regs); + + switch (remcomInBuffer[0]) { + case 's': + case 'c': + ptr = &remcomInBuffer[1]; + if (kgdb_hex2long(&ptr, &addr)) + regs->ret = addr; + fallthrough; + + case 'D': + case 'k': + atomic_set(&kgdb_cpu_doing_single_step, -1); + + if (remcomInBuffer[0] == 's') { + do_single_step(regs); + atomic_set(&kgdb_cpu_doing_single_step, + smp_processor_id()); + } + + return 0; + } + return -1; +} + +int kgdb_arch_init(void) +{ + single_step_data.armed = 0; + return 0; +} + +void kgdb_trap(struct pt_regs *regs) +{ + /* trap_s 3 is used for breakpoints that overwrite existing + * instructions, while trap_s 4 is used for compiled breakpoints. + * + * with trap_s 3 breakpoints the original instruction needs to be + * restored and continuation needs to start at the location of the + * breakpoint. + * + * with trap_s 4 (compiled) breakpoints, continuation needs to + * start after the breakpoint. + */ + if (regs->ecr_param == 3) + instruction_pointer(regs) -= BREAK_INSTR_SIZE; + + kgdb_handle_exception(1, SIGTRAP, 0, regs); +} + +void kgdb_arch_exit(void) +{ +} + +void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip) +{ + instruction_pointer(regs) = ip; +} + +void kgdb_call_nmi_hook(void *ignored) +{ + /* Default implementation passes get_irq_regs() but we don't */ + kgdb_nmicallback(raw_smp_processor_id(), NULL); +} + +const struct kgdb_arch arch_kgdb_ops = { + /* breakpoint instruction: TRAP_S 0x3 */ +#ifdef CONFIG_CPU_BIG_ENDIAN + .gdb_bpt_instr = {0x78, 0x7e}, +#else + .gdb_bpt_instr = {0x7e, 0x78}, +#endif +}; |