diff options
Diffstat (limited to 'arch/arm/kernel/ptrace.c')
| -rw-r--r-- | arch/arm/kernel/ptrace.c | 239 |
1 files changed, 239 insertions, 0 deletions
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c index f99d489822d5..e0cb6370ed14 100644 --- a/arch/arm/kernel/ptrace.c +++ b/arch/arm/kernel/ptrace.c @@ -19,6 +19,8 @@ #include <linux/init.h> #include <linux/signal.h> #include <linux/uaccess.h> +#include <linux/perf_event.h> +#include <linux/hw_breakpoint.h> #include <asm/pgtable.h> #include <asm/system.h> @@ -847,6 +849,232 @@ static int ptrace_setvfpregs(struct task_struct *tsk, void __user *data) } #endif +#ifdef CONFIG_HAVE_HW_BREAKPOINT +/* + * Convert a virtual register number into an index for a thread_info + * breakpoint array. Breakpoints are identified using positive numbers + * whilst watchpoints are negative. The registers are laid out as pairs + * of (address, control), each pair mapping to a unique hw_breakpoint struct. + * Register 0 is reserved for describing resource information. + */ +static int ptrace_hbp_num_to_idx(long num) +{ + if (num < 0) + num = (ARM_MAX_BRP << 1) - num; + return (num - 1) >> 1; +} + +/* + * Returns the virtual register number for the address of the + * breakpoint at index idx. + */ +static long ptrace_hbp_idx_to_num(int idx) +{ + long mid = ARM_MAX_BRP << 1; + long num = (idx << 1) + 1; + return num > mid ? mid - num : num; +} + +/* + * Handle hitting a HW-breakpoint. + */ +static void ptrace_hbptriggered(struct perf_event *bp, int unused, + struct perf_sample_data *data, + struct pt_regs *regs) +{ + struct arch_hw_breakpoint *bkpt = counter_arch_bp(bp); + long num; + int i; + siginfo_t info; + + for (i = 0; i < ARM_MAX_HBP_SLOTS; ++i) + if (current->thread.debug.hbp[i] == bp) + break; + + num = (i == ARM_MAX_HBP_SLOTS) ? 0 : ptrace_hbp_idx_to_num(i); + + info.si_signo = SIGTRAP; + info.si_errno = (int)num; + info.si_code = TRAP_HWBKPT; + info.si_addr = (void __user *)(bkpt->trigger); + + force_sig_info(SIGTRAP, &info, current); +} + +/* + * Set ptrace breakpoint pointers to zero for this task. + * This is required in order to prevent child processes from unregistering + * breakpoints held by their parent. + */ +void clear_ptrace_hw_breakpoint(struct task_struct *tsk) +{ + memset(tsk->thread.debug.hbp, 0, sizeof(tsk->thread.debug.hbp)); +} + +/* + * Unregister breakpoints from this task and reset the pointers in + * the thread_struct. + */ +void flush_ptrace_hw_breakpoint(struct task_struct *tsk) +{ + int i; + struct thread_struct *t = &tsk->thread; + + for (i = 0; i < ARM_MAX_HBP_SLOTS; i++) { + if (t->debug.hbp[i]) { + unregister_hw_breakpoint(t->debug.hbp[i]); + t->debug.hbp[i] = NULL; + } + } +} + +static u32 ptrace_get_hbp_resource_info(void) +{ + u8 num_brps, num_wrps, debug_arch, wp_len; + u32 reg = 0; + + num_brps = hw_breakpoint_slots(TYPE_INST); + num_wrps = hw_breakpoint_slots(TYPE_DATA); + debug_arch = arch_get_debug_arch(); + wp_len = arch_get_max_wp_len(); + + reg |= debug_arch; + reg <<= 8; + reg |= wp_len; + reg <<= 8; + reg |= num_wrps; + reg <<= 8; + reg |= num_brps; + + return reg; +} + +static struct perf_event *ptrace_hbp_create(struct task_struct *tsk, int type) +{ + struct perf_event_attr attr; + + ptrace_breakpoint_init(&attr); + + /* Initialise fields to sane defaults. */ + attr.bp_addr = 0; + attr.bp_len = HW_BREAKPOINT_LEN_4; + attr.bp_type = type; + attr.disabled = 1; + + return register_user_hw_breakpoint(&attr, ptrace_hbptriggered, tsk); +} + +static int ptrace_gethbpregs(struct task_struct *tsk, long num, + unsigned long __user *data) +{ + u32 reg; + int idx, ret = 0; + struct perf_event *bp; + struct arch_hw_breakpoint_ctrl arch_ctrl; + + if (num == 0) { + reg = ptrace_get_hbp_resource_info(); + } else { + idx = ptrace_hbp_num_to_idx(num); + if (idx < 0 || idx >= ARM_MAX_HBP_SLOTS) { + ret = -EINVAL; + goto out; + } + + bp = tsk->thread.debug.hbp[idx]; + if (!bp) { + reg = 0; + goto put; + } + + arch_ctrl = counter_arch_bp(bp)->ctrl; + + /* + * Fix up the len because we may have adjusted it + * to compensate for an unaligned address. + */ + while (!(arch_ctrl.len & 0x1)) + arch_ctrl.len >>= 1; + + if (idx & 0x1) + reg = encode_ctrl_reg(arch_ctrl); + else + reg = bp->attr.bp_addr; + } + +put: + if (put_user(reg, data)) + ret = -EFAULT; + +out: + return ret; +} + +static int ptrace_sethbpregs(struct task_struct *tsk, long num, + unsigned long __user *data) +{ + int idx, gen_len, gen_type, implied_type, ret = 0; + u32 user_val; + struct perf_event *bp; + struct arch_hw_breakpoint_ctrl ctrl; + struct perf_event_attr attr; + + if (num == 0) + goto out; + else if (num < 0) + implied_type = HW_BREAKPOINT_RW; + else + implied_type = HW_BREAKPOINT_X; + + idx = ptrace_hbp_num_to_idx(num); + if (idx < 0 || idx >= ARM_MAX_HBP_SLOTS) { + ret = -EINVAL; + goto out; + } + + if (get_user(user_val, data)) { + ret = -EFAULT; + goto out; + } + + bp = tsk->thread.debug.hbp[idx]; + if (!bp) { + bp = ptrace_hbp_create(tsk, implied_type); + if (IS_ERR(bp)) { + ret = PTR_ERR(bp); + goto out; + } + tsk->thread.debug.hbp[idx] = bp; + } + + attr = bp->attr; + + if (num & 0x1) { + /* Address */ + attr.bp_addr = user_val; + } else { + /* Control */ + decode_ctrl_reg(user_val, &ctrl); + ret = arch_bp_generic_fields(ctrl, &gen_len, &gen_type); + if (ret) + goto out; + + if ((gen_type & implied_type) != gen_type) { + ret = -EINVAL; + goto out; + } + + attr.bp_len = gen_len; + attr.bp_type = gen_type; + attr.disabled = !ctrl.enabled; + } + + ret = modify_user_hw_breakpoint(bp, &attr); +out: + return ret; +} +#endif + long arch_ptrace(struct task_struct *child, long request, long addr, long data) { int ret; @@ -916,6 +1144,17 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data) break; #endif +#ifdef CONFIG_HAVE_HW_BREAKPOINT + case PTRACE_GETHBPREGS: + ret = ptrace_gethbpregs(child, addr, + (unsigned long __user *)data); + break; + case PTRACE_SETHBPREGS: + ret = ptrace_sethbpregs(child, addr, + (unsigned long __user *)data); + break; +#endif + default: ret = ptrace_request(child, request, addr, data); break; |