cregit-Linux how code gets into the kernel

Release 4.14 arch/arm64/kernel/kgdb.c

/*
 * AArch64 KGDB support
 *
 * Based on arch/arm/kernel/kgdb.c
 *
 * Copyright (C) 2013 Cavium Inc.
 * Author: Vijaya Kumar K <vijaya.kumar@caviumnetworks.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/bug.h>
#include <linux/irq.h>
#include <linux/kdebug.h>
#include <linux/kgdb.h>
#include <linux/kprobes.h>
#include <linux/sched/task_stack.h>

#include <asm/debug-monitors.h>
#include <asm/insn.h>
#include <asm/traps.h>


struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = {
	{ "x0", 8, offsetof(struct pt_regs, regs[0])},
	{ "x1", 8, offsetof(struct pt_regs, regs[1])},
	{ "x2", 8, offsetof(struct pt_regs, regs[2])},
	{ "x3", 8, offsetof(struct pt_regs, regs[3])},
	{ "x4", 8, offsetof(struct pt_regs, regs[4])},
	{ "x5", 8, offsetof(struct pt_regs, regs[5])},
	{ "x6", 8, offsetof(struct pt_regs, regs[6])},
	{ "x7", 8, offsetof(struct pt_regs, regs[7])},
	{ "x8", 8, offsetof(struct pt_regs, regs[8])},
	{ "x9", 8, offsetof(struct pt_regs, regs[9])},
	{ "x10", 8, offsetof(struct pt_regs, regs[10])},
	{ "x11", 8, offsetof(struct pt_regs, regs[11])},
	{ "x12", 8, offsetof(struct pt_regs, regs[12])},
	{ "x13", 8, offsetof(struct pt_regs, regs[13])},
	{ "x14", 8, offsetof(struct pt_regs, regs[14])},
	{ "x15", 8, offsetof(struct pt_regs, regs[15])},
	{ "x16", 8, offsetof(struct pt_regs, regs[16])},
	{ "x17", 8, offsetof(struct pt_regs, regs[17])},
	{ "x18", 8, offsetof(struct pt_regs, regs[18])},
	{ "x19", 8, offsetof(struct pt_regs, regs[19])},
	{ "x20", 8, offsetof(struct pt_regs, regs[20])},
	{ "x21", 8, offsetof(struct pt_regs, regs[21])},
	{ "x22", 8, offsetof(struct pt_regs, regs[22])},
	{ "x23", 8, offsetof(struct pt_regs, regs[23])},
	{ "x24", 8, offsetof(struct pt_regs, regs[24])},
	{ "x25", 8, offsetof(struct pt_regs, regs[25])},
	{ "x26", 8, offsetof(struct pt_regs, regs[26])},
	{ "x27", 8, offsetof(struct pt_regs, regs[27])},
	{ "x28", 8, offsetof(struct pt_regs, regs[28])},
	{ "x29", 8, offsetof(struct pt_regs, regs[29])},
	{ "x30", 8, offsetof(struct pt_regs, regs[30])},
	{ "sp", 8, offsetof(struct pt_regs, sp)},
	{ "pc", 8, offsetof(struct pt_regs, pc)},
	/*
         * struct pt_regs thinks PSTATE is 64-bits wide but gdb remote
         * protocol disagrees. Therefore we must extract only the lower
         * 32-bits. Look for the big comment in asm/kgdb.h for more
         * detail.
         */
	{ "pstate", 4, offsetof(struct pt_regs, pstate)
#ifdef CONFIG_CPU_BIG_ENDIAN
							+ 4
#endif
	},
	{ "v0", 16, -1 },
	{ "v1", 16, -1 },
	{ "v2", 16, -1 },
	{ "v3", 16, -1 },
	{ "v4", 16, -1 },
	{ "v5", 16, -1 },
	{ "v6", 16, -1 },
	{ "v7", 16, -1 },
	{ "v8", 16, -1 },
	{ "v9", 16, -1 },
	{ "v10", 16, -1 },
	{ "v11", 16, -1 },
	{ "v12", 16, -1 },
	{ "v13", 16, -1 },
	{ "v14", 16, -1 },
	{ "v15", 16, -1 },
	{ "v16", 16, -1 },
	{ "v17", 16, -1 },
	{ "v18", 16, -1 },
	{ "v19", 16, -1 },
	{ "v20", 16, -1 },
	{ "v21", 16, -1 },
	{ "v22", 16, -1 },
	{ "v23", 16, -1 },
	{ "v24", 16, -1 },
	{ "v25", 16, -1 },
	{ "v26", 16, -1 },
	{ "v27", 16, -1 },
	{ "v28", 16, -1 },
	{ "v29", 16, -1 },
	{ "v30", 16, -1 },
	{ "v31", 16, -1 },
	{ "fpsr", 4, -1 },
	{ "fpcr", 4, -1 },
};


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].offset != -1) memcpy(mem, (void *)regs + dbg_reg_def[regno].offset, dbg_reg_def[regno].size); else memset(mem, 0, dbg_reg_def[regno].size); return dbg_reg_def[regno].name; }

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Vijaya Kumar K91100.00%1100.00%
Total91100.00%1100.00%


int dbg_set_reg(int regno, void *mem, struct pt_regs *regs) { if (regno >= DBG_MAX_REG_NUM || regno < 0) 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; }

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Vijaya Kumar K71100.00%1100.00%
Total71100.00%1100.00%


void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task) { struct pt_regs *thread_regs; /* Initialize to zero */ memset((char *)gdb_regs, 0, NUMREGBYTES); thread_regs = task_pt_regs(task); memcpy((void *)gdb_regs, (void *)thread_regs->regs, GP_REG_BYTES); /* Special case for PSTATE (check comments in asm/kgdb.h for details) */ dbg_get_reg(33, gdb_regs + GP_REG_BYTES, thread_regs); }

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Vijaya Kumar K6083.33%150.00%
Daniel R Thompson1216.67%150.00%
Total72100.00%2100.00%


void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc) { regs->pc = pc; }

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Vijaya Kumar K20100.00%1100.00%
Total20100.00%1100.00%

static int compiled_break;
static void kgdb_arch_update_addr(struct pt_regs *regs, char *remcom_in_buffer) { unsigned long addr; char *ptr; ptr = &remcom_in_buffer[1]; if (kgdb_hex2long(&ptr, &addr)) kgdb_arch_set_pc(regs, addr); else if (compiled_break == 1) kgdb_arch_set_pc(regs, regs->pc + 4); compiled_break = 0; }

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Vijaya Kumar K71100.00%1100.00%
Total71100.00%1100.00%


int kgdb_arch_handle_exception(int exception_vector, int signo, int err_code, char *remcom_in_buffer, char *remcom_out_buffer, struct pt_regs *linux_regs) { int err; switch (remcom_in_buffer[0]) { case 'D': case 'k': /* * Packet D (Detach), k (kill). No special handling * is required here. Handle same as c packet. */ case 'c': /* * Packet c (Continue) to continue executing. * Set pc to required address. * Try to read optional parameter and set pc. * If this was a compiled breakpoint, we need to move * to the next instruction else we will just breakpoint * over and over again. */ kgdb_arch_update_addr(linux_regs, remcom_in_buffer); atomic_set(&kgdb_cpu_doing_single_step, -1); kgdb_single_step = 0; /* * Received continue command, disable single step */ if (kernel_active_single_step()) kernel_disable_single_step(); err = 0; break; case 's': /* * Update step address value with address passed * with step packet. * On debug exception return PC is copied to ELR * So just update PC. * If no step address is passed, resume from the address * pointed by PC. Do not update PC */ kgdb_arch_update_addr(linux_regs, remcom_in_buffer); atomic_set(&kgdb_cpu_doing_single_step, raw_smp_processor_id()); kgdb_single_step = 1; /* * Enable single step handling */ if (!kernel_active_single_step()) kernel_enable_single_step(linux_regs); err = 0; break; default: err = -1; } return err; }

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Vijaya Kumar K134100.00%2100.00%
Total134100.00%2100.00%


static int kgdb_brk_fn(struct pt_regs *regs, unsigned int esr) { kgdb_handle_exception(1, SIGTRAP, 0, regs); return 0; }

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Vijaya Kumar K29100.00%1100.00%
Total29100.00%1100.00%

NOKPROBE_SYMBOL(kgdb_brk_fn)
static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int esr) { compiled_break = 1; kgdb_handle_exception(1, SIGTRAP, 0, regs); return 0; }

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Vijaya Kumar K33100.00%1100.00%
Total33100.00%1100.00%

NOKPROBE_SYMBOL(kgdb_compiled_brk_fn);
static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned int esr) { if (!kgdb_single_step) return DBG_HOOK_ERROR; kgdb_handle_exception(1, SIGTRAP, 0, regs); return 0; }

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Vijaya Kumar K2978.38%150.00%
Pratyush Anand821.62%150.00%
Total37100.00%2100.00%

NOKPROBE_SYMBOL(kgdb_step_brk_fn); static struct break_hook kgdb_brkpt_hook = { .esr_mask = 0xffffffff, .esr_val = (u32)ESR_ELx_VAL_BRK64(KGDB_DYN_DBG_BRK_IMM), .fn = kgdb_brk_fn }; static struct break_hook kgdb_compiled_brkpt_hook = { .esr_mask = 0xffffffff, .esr_val = (u32)ESR_ELx_VAL_BRK64(KGDB_COMPILED_DBG_BRK_IMM), .fn = kgdb_compiled_brk_fn }; static struct step_hook kgdb_step_hook = { .fn = kgdb_step_brk_fn };
static void kgdb_call_nmi_hook(void *ignored) { kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); }

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Vijaya Kumar K19100.00%1100.00%
Total19100.00%1100.00%


void kgdb_roundup_cpus(unsigned long flags) { local_irq_enable(); smp_call_function(kgdb_call_nmi_hook, NULL, 0); local_irq_disable(); }

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Vijaya Kumar K24100.00%1100.00%
Total24100.00%1100.00%


static int __kgdb_notify(struct die_args *args, unsigned long cmd) { struct pt_regs *regs = args->regs; if (kgdb_handle_exception(1, args->signr, cmd, regs)) return NOTIFY_DONE; return NOTIFY_STOP; }

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Vijaya Kumar K45100.00%1100.00%
Total45100.00%1100.00%


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; }

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Vijaya Kumar K48100.00%1100.00%
Total48100.00%1100.00%

static struct notifier_block kgdb_notifier = { .notifier_call = kgdb_notify, /* * Want to be lowest priority */ .priority = -INT_MAX, }; /* * kgdb_arch_init - Perform any architecture specific initialization. * This function will handle the initialization of any architecture * specific callbacks. */
int kgdb_arch_init(void) { int ret = register_die_notifier(&kgdb_notifier); if (ret != 0) return ret; register_break_hook(&kgdb_brkpt_hook); register_break_hook(&kgdb_compiled_brkpt_hook); register_step_hook(&kgdb_step_hook); return 0; }

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Vijaya Kumar K46100.00%2100.00%
Total46100.00%2100.00%

/* * kgdb_arch_exit - Perform any architecture specific uninitalization. * This function will handle the uninitalization of any architecture * specific callbacks, for dynamic registration and unregistration. */
void kgdb_arch_exit(void) { unregister_break_hook(&kgdb_brkpt_hook); unregister_break_hook(&kgdb_compiled_brkpt_hook); unregister_step_hook(&kgdb_step_hook); unregister_die_notifier(&kgdb_notifier); }

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Vijaya Kumar K31100.00%2100.00%
Total31100.00%2100.00%

struct kgdb_arch arch_kgdb_ops;
int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt) { int err; BUILD_BUG_ON(AARCH64_INSN_SIZE != BREAK_INSTR_SIZE); err = aarch64_insn_read((void *)bpt->bpt_addr, (u32 *)bpt->saved_instr); if (err) return err; return aarch64_insn_write((void *)bpt->bpt_addr, (u32)AARCH64_BREAK_KGDB_DYN_DBG); }

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AKASHI Takahiro5889.23%133.33%
Dave P Martin69.23%133.33%
Vijaya Kumar K11.54%133.33%
Total65100.00%3100.00%


int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt) { return aarch64_insn_write((void *)bpt->bpt_addr, *(u32 *)bpt->saved_instr); }

Contributors

PersonTokensPropCommitsCommitProp
AKASHI Takahiro2890.32%133.33%
Dave P Martin26.45%133.33%
Vijaya Kumar K13.23%133.33%
Total31100.00%3100.00%


Overall Contributors

PersonTokensPropCommitsCommitProp
Vijaya Kumar K166790.89%218.18%
AKASHI Takahiro965.23%19.09%
Pratyush Anand251.36%218.18%
Daniel R Thompson241.31%19.09%
Dave P Martin160.87%218.18%
Ingo Molnar30.16%19.09%
Catalin Marinas20.11%19.09%
Adam Buchbinder10.05%19.09%
Total1834100.00%11100.00%
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