diff options
Diffstat (limited to 'arch/arm64/kernel/debug-monitors.c')
| -rw-r--r-- | arch/arm64/kernel/debug-monitors.c | 166 |
1 files changed, 151 insertions, 15 deletions
diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c index f4726dc054b3..e3b37ee9076a 100644 --- a/arch/arm64/kernel/debug-monitors.c +++ b/arch/arm64/kernel/debug-monitors.c @@ -24,21 +24,13 @@ #include <linux/init.h> #include <linux/ptrace.h> #include <linux/stat.h> +#include <linux/uaccess.h> #include <asm/debug-monitors.h> #include <asm/local.h> #include <asm/cputype.h> #include <asm/system_misc.h> -/* 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) { @@ -137,7 +129,6 @@ void disable_debug_monitors(enum debug_el el) 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, @@ -156,8 +147,9 @@ static struct notifier_block __cpuinitdata os_lock_nb = { static int __cpuinit debug_monitors_init(void) { /* 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(); + local_dbg_enable(); /* Register hotplug handler. */ register_cpu_notifier(&os_lock_nb); @@ -187,6 +179,48 @@ static void clear_regs_spsr_ss(struct pt_regs *regs) regs->pstate = spsr; } +/* EL1 Single Step Handler hooks */ +static LIST_HEAD(step_hook); +static DEFINE_RWLOCK(step_hook_lock); + +void register_step_hook(struct step_hook *hook) +{ + write_lock(&step_hook_lock); + list_add(&hook->node, &step_hook); + write_unlock(&step_hook_lock); +} + +void unregister_step_hook(struct step_hook *hook) +{ + write_lock(&step_hook_lock); + list_del(&hook->node); + write_unlock(&step_hook_lock); +} + +/* + * Call registered single step handers + * 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; + + read_lock(&step_hook_lock); + + list_for_each_entry(hook, &step_hook, node) { + retval = hook->fn(regs, esr); + if (retval == DBG_HOOK_HANDLED) + break; + } + + read_unlock(&step_hook_lock); + + return retval; +} + static int single_step_handler(unsigned long addr, unsigned int esr, struct pt_regs *regs) { @@ -214,7 +248,9 @@ static int single_step_handler(unsigned long addr, unsigned int esr, */ 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 +262,113 @@ static int single_step_handler(unsigned long addr, unsigned int esr, 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_RWLOCK(break_hook_lock); + +void register_break_hook(struct break_hook *hook) +{ + write_lock(&break_hook_lock); + list_add(&hook->node, &break_hook); + write_unlock(&break_hook_lock); +} + +void unregister_break_hook(struct break_hook *hook) +{ + write_lock(&break_hook_lock); + list_del(&hook->node); + write_unlock(&break_hook_lock); +} + +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; + + read_lock(&break_hook_lock); + list_for_each_entry(hook, &break_hook, node) + if ((esr & hook->esr_mask) == hook->esr_val) + fn = hook->fn; + read_unlock(&break_hook_lock); + + 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; + unsigned int 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(instr, (u16 __user *)pc); + if (instr == AARCH32_BREAK_THUMB2_LO) { + /* get second half of 32-bit Thumb-2 instruction */ + get_user(instr, (u16 __user *)(pc + 2)); + bp = instr == AARCH32_BREAK_THUMB2_HI; + } else { + bp = instr == AARCH32_BREAK_THUMB; + } + } else { + /* 32-bit ARM instruction */ + get_user(instr, (u32 __user *)pc); + bp = (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) |