--- zzzz-none-000/linux-3.10.107/arch/arm64/kernel/debug-monitors.c 2017-06-27 09:49:32.000000000 +0000 +++ scorpion-7490-727/linux-3.10.107/arch/arm64/kernel/debug-monitors.c 2021-02-04 17:41:59.000000000 +0000 @@ -24,25 +24,18 @@ #include #include #include +#include -#include -#include +#include #include +#include #include -/* Low-level stepping controls. */ -#define DBG_MDSCR_SS (1 << 0) -#define DBG_SPSR_SS (1 << 21) - -/* MDSCR_EL1 enabling bits */ -#define DBG_MDSCR_KDE (1 << 13) -#define DBG_MDSCR_MDE (1 << 15) -#define DBG_MDSCR_MASK ~(DBG_MDSCR_KDE | DBG_MDSCR_MDE) - /* Determine debug architecture. */ u8 debug_monitors_arch(void) { - return read_cpuid(ID_AA64DFR0_EL1) & 0xf; + return cpuid_feature_extract_field(read_system_reg(SYS_ID_AA64DFR0_EL1), + ID_AA64DFR0_DEBUGVER_SHIFT); } /* @@ -67,7 +60,7 @@ * Allow root to disable self-hosted debug from userspace. * This is useful if you want to connect an external JTAG debugger. */ -static u32 debug_enabled = 1; +static bool debug_enabled = true; static int create_debug_debugfs_entry(void) { @@ -78,7 +71,7 @@ static int __init early_debug_disable(char *buf) { - debug_enabled = 0; + debug_enabled = false; return 0; } @@ -88,20 +81,20 @@ * Keep track of debug users on each core. * The ref counts are per-cpu so we use a local_t type. */ -static DEFINE_PER_CPU(local_t, mde_ref_count); -static DEFINE_PER_CPU(local_t, kde_ref_count); +static DEFINE_PER_CPU(int, mde_ref_count); +static DEFINE_PER_CPU(int, kde_ref_count); -void enable_debug_monitors(enum debug_el el) +void enable_debug_monitors(enum dbg_active_el el) { u32 mdscr, enable = 0; WARN_ON(preemptible()); - if (local_inc_return(&__get_cpu_var(mde_ref_count)) == 1) + if (this_cpu_inc_return(mde_ref_count) == 1) enable = DBG_MDSCR_MDE; if (el == DBG_ACTIVE_EL1 && - local_inc_return(&__get_cpu_var(kde_ref_count)) == 1) + this_cpu_inc_return(kde_ref_count) == 1) enable |= DBG_MDSCR_KDE; if (enable && debug_enabled) { @@ -111,17 +104,17 @@ } } -void disable_debug_monitors(enum debug_el el) +void disable_debug_monitors(enum dbg_active_el el) { u32 mdscr, disable = 0; WARN_ON(preemptible()); - if (local_dec_and_test(&__get_cpu_var(mde_ref_count))) + if (this_cpu_dec_return(mde_ref_count) == 0) disable = ~DBG_MDSCR_MDE; if (el == DBG_ACTIVE_EL1 && - local_dec_and_test(&__get_cpu_var(kde_ref_count))) + this_cpu_dec_return(kde_ref_count) == 0) disable &= ~DBG_MDSCR_KDE; if (disable) { @@ -137,30 +130,33 @@ static void clear_os_lock(void *unused) { asm volatile("msr oslar_el1, %0" : : "r" (0)); - isb(); } -static int __cpuinit os_lock_notify(struct notifier_block *self, +static int os_lock_notify(struct notifier_block *self, unsigned long action, void *data) { int cpu = (unsigned long)data; - if (action == CPU_ONLINE) + if ((action & ~CPU_TASKS_FROZEN) == CPU_ONLINE) smp_call_function_single(cpu, clear_os_lock, NULL, 1); return NOTIFY_OK; } -static struct notifier_block __cpuinitdata os_lock_nb = { +static struct notifier_block os_lock_nb = { .notifier_call = os_lock_notify, }; -static int __cpuinit debug_monitors_init(void) +static int debug_monitors_init(void) { + cpu_notifier_register_begin(); + /* Clear the OS lock. */ - smp_call_function(clear_os_lock, NULL, 1); - clear_os_lock(NULL); + on_each_cpu(clear_os_lock, NULL, 1); + isb(); /* Register hotplug handler. */ - register_cpu_notifier(&os_lock_nb); + __register_cpu_notifier(&os_lock_nb); + + cpu_notifier_register_done(); return 0; } postcore_initcall(debug_monitors_init); @@ -187,6 +183,49 @@ regs->pstate = spsr; } +/* EL1 Single Step Handler hooks */ +static LIST_HEAD(step_hook); +static DEFINE_SPINLOCK(step_hook_lock); + +void register_step_hook(struct step_hook *hook) +{ + spin_lock(&step_hook_lock); + list_add_rcu(&hook->node, &step_hook); + spin_unlock(&step_hook_lock); +} + +void unregister_step_hook(struct step_hook *hook) +{ + spin_lock(&step_hook_lock); + list_del_rcu(&hook->node); + spin_unlock(&step_hook_lock); + synchronize_rcu(); +} + +/* + * Call registered single step handlers + * There is no Syndrome info to check for determining the handler. + * So we call all the registered handlers, until the right handler is + * found which returns zero. + */ +static int call_step_hook(struct pt_regs *regs, unsigned int esr) +{ + struct step_hook *hook; + int retval = DBG_HOOK_ERROR; + + rcu_read_lock(); + + list_for_each_entry_rcu(hook, &step_hook, node) { + retval = hook->fn(regs, esr); + if (retval == DBG_HOOK_HANDLED) + break; + } + + rcu_read_unlock(); + + return retval; +} + static int single_step_handler(unsigned long addr, unsigned int esr, struct pt_regs *regs) { @@ -214,7 +253,9 @@ */ user_rewind_single_step(current); } else { - /* TODO: route to KGDB */ + if (call_step_hook(regs, esr) == DBG_HOOK_HANDLED) + return 0; + pr_warning("Unexpected kernel single-step exception at EL1\n"); /* * Re-enable stepping since we know that we will be @@ -226,13 +267,118 @@ return 0; } -static int __init single_step_init(void) +/* + * Breakpoint handler is re-entrant as another breakpoint can + * hit within breakpoint handler, especically in kprobes. + * Use reader/writer locks instead of plain spinlock. + */ +static LIST_HEAD(break_hook); +static DEFINE_SPINLOCK(break_hook_lock); + +void register_break_hook(struct break_hook *hook) +{ + spin_lock(&break_hook_lock); + list_add_rcu(&hook->node, &break_hook); + spin_unlock(&break_hook_lock); +} + +void unregister_break_hook(struct break_hook *hook) +{ + spin_lock(&break_hook_lock); + list_del_rcu(&hook->node); + spin_unlock(&break_hook_lock); + synchronize_rcu(); +} + +static int call_break_hook(struct pt_regs *regs, unsigned int esr) +{ + struct break_hook *hook; + int (*fn)(struct pt_regs *regs, unsigned int esr) = NULL; + + rcu_read_lock(); + list_for_each_entry_rcu(hook, &break_hook, node) + if ((esr & hook->esr_mask) == hook->esr_val) + fn = hook->fn; + rcu_read_unlock(); + + return fn ? fn(regs, esr) : DBG_HOOK_ERROR; +} + +static int brk_handler(unsigned long addr, unsigned int esr, + struct pt_regs *regs) +{ + siginfo_t info; + + if (user_mode(regs)) { + info = (siginfo_t) { + .si_signo = SIGTRAP, + .si_errno = 0, + .si_code = TRAP_BRKPT, + .si_addr = (void __user *)instruction_pointer(regs), + }; + + force_sig_info(SIGTRAP, &info, current); + } else if (call_break_hook(regs, esr) != DBG_HOOK_HANDLED) { + pr_warning("Unexpected kernel BRK exception at EL1\n"); + return -EFAULT; + } + + return 0; +} + +int aarch32_break_handler(struct pt_regs *regs) +{ + siginfo_t info; + u32 arm_instr; + u16 thumb_instr; + bool bp = false; + void __user *pc = (void __user *)instruction_pointer(regs); + + if (!compat_user_mode(regs)) + return -EFAULT; + + if (compat_thumb_mode(regs)) { + /* get 16-bit Thumb instruction */ + get_user(thumb_instr, (u16 __user *)pc); + thumb_instr = le16_to_cpu(thumb_instr); + if (thumb_instr == AARCH32_BREAK_THUMB2_LO) { + /* get second half of 32-bit Thumb-2 instruction */ + get_user(thumb_instr, (u16 __user *)(pc + 2)); + thumb_instr = le16_to_cpu(thumb_instr); + bp = thumb_instr == AARCH32_BREAK_THUMB2_HI; + } else { + bp = thumb_instr == AARCH32_BREAK_THUMB; + } + } else { + /* 32-bit ARM instruction */ + get_user(arm_instr, (u32 __user *)pc); + arm_instr = le32_to_cpu(arm_instr); + bp = (arm_instr & ~0xf0000000) == AARCH32_BREAK_ARM; + } + + if (!bp) + return -EFAULT; + + info = (siginfo_t) { + .si_signo = SIGTRAP, + .si_errno = 0, + .si_code = TRAP_BRKPT, + .si_addr = pc, + }; + + force_sig_info(SIGTRAP, &info, current); + return 0; +} + +static int __init debug_traps_init(void) { hook_debug_fault_code(DBG_ESR_EVT_HWSS, single_step_handler, SIGTRAP, TRAP_HWBKPT, "single-step handler"); + hook_debug_fault_code(DBG_ESR_EVT_BRK, brk_handler, SIGTRAP, + TRAP_BRKPT, "ptrace BRK handler"); return 0; } -arch_initcall(single_step_init); +arch_initcall(debug_traps_init); /* Re-enable single step for syscall restarting. */ void user_rewind_single_step(struct task_struct *task)