diff options
Diffstat (limited to 'arch/sh/kernel/hw_breakpoint.c')
-rw-r--r-- | arch/sh/kernel/hw_breakpoint.c | 420 |
1 files changed, 420 insertions, 0 deletions
diff --git a/arch/sh/kernel/hw_breakpoint.c b/arch/sh/kernel/hw_breakpoint.c new file mode 100644 index 00000000000..efae6ab3d54 --- /dev/null +++ b/arch/sh/kernel/hw_breakpoint.c @@ -0,0 +1,420 @@ +/* + * arch/sh/kernel/hw_breakpoint.c + * + * Unified kernel/user-space hardware breakpoint facility for the on-chip UBC. + * + * Copyright (C) 2009 - 2010 Paul Mundt + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + */ +#include <linux/init.h> +#include <linux/perf_event.h> +#include <linux/hw_breakpoint.h> +#include <linux/percpu.h> +#include <linux/kallsyms.h> +#include <linux/notifier.h> +#include <linux/kprobes.h> +#include <linux/kdebug.h> +#include <linux/io.h> +#include <linux/clk.h> +#include <asm/hw_breakpoint.h> +#include <asm/mmu_context.h> +#include <asm/ptrace.h> + +/* + * Stores the breakpoints currently in use on each breakpoint address + * register for each cpus + */ +static DEFINE_PER_CPU(struct perf_event *, bp_per_reg[HBP_NUM]); + +/* + * A dummy placeholder for early accesses until the CPUs get a chance to + * register their UBCs later in the boot process. + */ +static struct sh_ubc ubc_dummy = { .num_events = 0 }; + +static struct sh_ubc *sh_ubc __read_mostly = &ubc_dummy; + +/* + * Install a perf counter breakpoint. + * + * We seek a free UBC channel and use it for this breakpoint. + * + * Atomic: we hold the counter->ctx->lock and we only handle variables + * and registers local to this cpu. + */ +int arch_install_hw_breakpoint(struct perf_event *bp) +{ + struct arch_hw_breakpoint *info = counter_arch_bp(bp); + int i; + + for (i = 0; i < sh_ubc->num_events; i++) { + struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]); + + if (!*slot) { + *slot = bp; + break; + } + } + + if (WARN_ONCE(i == sh_ubc->num_events, "Can't find any breakpoint slot")) + return -EBUSY; + + clk_enable(sh_ubc->clk); + sh_ubc->enable(info, i); + + return 0; +} + +/* + * Uninstall the breakpoint contained in the given counter. + * + * First we search the debug address register it uses and then we disable + * it. + * + * Atomic: we hold the counter->ctx->lock and we only handle variables + * and registers local to this cpu. + */ +void arch_uninstall_hw_breakpoint(struct perf_event *bp) +{ + struct arch_hw_breakpoint *info = counter_arch_bp(bp); + int i; + + for (i = 0; i < sh_ubc->num_events; i++) { + struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]); + + if (*slot == bp) { + *slot = NULL; + break; + } + } + + if (WARN_ONCE(i == sh_ubc->num_events, "Can't find any breakpoint slot")) + return; + + sh_ubc->disable(info, i); + clk_disable(sh_ubc->clk); +} + +static int get_hbp_len(u16 hbp_len) +{ + unsigned int len_in_bytes = 0; + + switch (hbp_len) { + case SH_BREAKPOINT_LEN_1: + len_in_bytes = 1; + break; + case SH_BREAKPOINT_LEN_2: + len_in_bytes = 2; + break; + case SH_BREAKPOINT_LEN_4: + len_in_bytes = 4; + break; + case SH_BREAKPOINT_LEN_8: + len_in_bytes = 8; + break; + } + return len_in_bytes; +} + +/* + * Check for virtual address in kernel space. + */ +int arch_check_bp_in_kernelspace(struct perf_event *bp) +{ + unsigned int len; + unsigned long va; + struct arch_hw_breakpoint *info = counter_arch_bp(bp); + + va = info->address; + len = get_hbp_len(info->len); + + return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE); +} + +int arch_bp_generic_fields(int sh_len, int sh_type, + int *gen_len, int *gen_type) +{ + /* Len */ + switch (sh_len) { + case SH_BREAKPOINT_LEN_1: + *gen_len = HW_BREAKPOINT_LEN_1; + break; + case SH_BREAKPOINT_LEN_2: + *gen_len = HW_BREAKPOINT_LEN_2; + break; + case SH_BREAKPOINT_LEN_4: + *gen_len = HW_BREAKPOINT_LEN_4; + break; + case SH_BREAKPOINT_LEN_8: + *gen_len = HW_BREAKPOINT_LEN_8; + break; + default: + return -EINVAL; + } + + /* Type */ + switch (sh_type) { + case SH_BREAKPOINT_READ: + *gen_type = HW_BREAKPOINT_R; + case SH_BREAKPOINT_WRITE: + *gen_type = HW_BREAKPOINT_W; + break; + case SH_BREAKPOINT_RW: + *gen_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R; + break; + default: + return -EINVAL; + } + + return 0; +} + +static int arch_build_bp_info(struct perf_event *bp) +{ + struct arch_hw_breakpoint *info = counter_arch_bp(bp); + + info->address = bp->attr.bp_addr; + + /* Len */ + switch (bp->attr.bp_len) { + case HW_BREAKPOINT_LEN_1: + info->len = SH_BREAKPOINT_LEN_1; + break; + case HW_BREAKPOINT_LEN_2: + info->len = SH_BREAKPOINT_LEN_2; + break; + case HW_BREAKPOINT_LEN_4: + info->len = SH_BREAKPOINT_LEN_4; + break; + case HW_BREAKPOINT_LEN_8: + info->len = SH_BREAKPOINT_LEN_8; + break; + default: + return -EINVAL; + } + + /* Type */ + switch (bp->attr.bp_type) { + case HW_BREAKPOINT_R: + info->type = SH_BREAKPOINT_READ; + break; + case HW_BREAKPOINT_W: + info->type = SH_BREAKPOINT_WRITE; + break; + case HW_BREAKPOINT_W | HW_BREAKPOINT_R: + info->type = SH_BREAKPOINT_RW; + break; + default: + return -EINVAL; + } + + return 0; +} + +/* + * Validate the arch-specific HW Breakpoint register settings + */ +int arch_validate_hwbkpt_settings(struct perf_event *bp) +{ + struct arch_hw_breakpoint *info = counter_arch_bp(bp); + unsigned int align; + int ret; + + ret = arch_build_bp_info(bp); + if (ret) + return ret; + + ret = -EINVAL; + + switch (info->len) { + case SH_BREAKPOINT_LEN_1: + align = 0; + break; + case SH_BREAKPOINT_LEN_2: + align = 1; + break; + case SH_BREAKPOINT_LEN_4: + align = 3; + break; + case SH_BREAKPOINT_LEN_8: + align = 7; + break; + default: + return ret; + } + + /* + * For kernel-addresses, either the address or symbol name can be + * specified. + */ + if (info->name) + info->address = (unsigned long)kallsyms_lookup_name(info->name); + + /* + * Check that the low-order bits of the address are appropriate + * for the alignment implied by len. + */ + if (info->address & align) + return -EINVAL; + + return 0; +} + +/* + * Release the user breakpoints used by ptrace + */ +void flush_ptrace_hw_breakpoint(struct task_struct *tsk) +{ + int i; + struct thread_struct *t = &tsk->thread; + + for (i = 0; i < sh_ubc->num_events; i++) { + unregister_hw_breakpoint(t->ptrace_bps[i]); + t->ptrace_bps[i] = NULL; + } +} + +static int __kprobes hw_breakpoint_handler(struct die_args *args) +{ + int cpu, i, rc = NOTIFY_STOP; + struct perf_event *bp; + unsigned int cmf, resume_mask; + + /* + * Do an early return if none of the channels triggered. + */ + cmf = sh_ubc->triggered_mask(); + if (unlikely(!cmf)) + return NOTIFY_DONE; + + /* + * By default, resume all of the active channels. + */ + resume_mask = sh_ubc->active_mask(); + + /* + * Disable breakpoints during exception handling. + */ + sh_ubc->disable_all(); + + cpu = get_cpu(); + for (i = 0; i < sh_ubc->num_events; i++) { + unsigned long event_mask = (1 << i); + + if (likely(!(cmf & event_mask))) + continue; + + /* + * The counter may be concurrently released but that can only + * occur from a call_rcu() path. We can then safely fetch + * the breakpoint, use its callback, touch its counter + * while we are in an rcu_read_lock() path. + */ + rcu_read_lock(); + + bp = per_cpu(bp_per_reg[i], cpu); + if (bp) + rc = NOTIFY_DONE; + + /* + * Reset the condition match flag to denote completion of + * exception handling. + */ + sh_ubc->clear_triggered_mask(event_mask); + + /* + * bp can be NULL due to concurrent perf counter + * removing. + */ + if (!bp) { + rcu_read_unlock(); + break; + } + + /* + * Don't restore the channel if the breakpoint is from + * ptrace, as it always operates in one-shot mode. + */ + if (bp->overflow_handler == ptrace_triggered) + resume_mask &= ~(1 << i); + + perf_bp_event(bp, args->regs); + + /* Deliver the signal to userspace */ + if (!arch_check_bp_in_kernelspace(bp)) { + siginfo_t info; + + info.si_signo = args->signr; + info.si_errno = notifier_to_errno(rc); + info.si_code = TRAP_HWBKPT; + + force_sig_info(args->signr, &info, current); + } + + rcu_read_unlock(); + } + + if (cmf == 0) + rc = NOTIFY_DONE; + + sh_ubc->enable_all(resume_mask); + + put_cpu(); + + return rc; +} + +BUILD_TRAP_HANDLER(breakpoint) +{ + unsigned long ex = lookup_exception_vector(); + TRAP_HANDLER_DECL; + + notify_die(DIE_BREAKPOINT, "breakpoint", regs, 0, ex, SIGTRAP); +} + +/* + * Handle debug exception notifications. + */ +int __kprobes hw_breakpoint_exceptions_notify(struct notifier_block *unused, + unsigned long val, void *data) +{ + struct die_args *args = data; + + if (val != DIE_BREAKPOINT) + return NOTIFY_DONE; + + /* + * If the breakpoint hasn't been triggered by the UBC, it's + * probably from a debugger, so don't do anything more here. + * + * This also permits the UBC interface clock to remain off for + * non-UBC breakpoints, as we don't need to check the triggered + * or active channel masks. + */ + if (args->trapnr != sh_ubc->trap_nr) + return NOTIFY_DONE; + + return hw_breakpoint_handler(data); +} + +void hw_breakpoint_pmu_read(struct perf_event *bp) +{ + /* TODO */ +} + +int register_sh_ubc(struct sh_ubc *ubc) +{ + /* Bail if it's already assigned */ + if (sh_ubc != &ubc_dummy) + return -EBUSY; + sh_ubc = ubc; + + pr_info("HW Breakpoints: %s UBC support registered\n", ubc->name); + + WARN_ON(ubc->num_events > HBP_NUM); + + return 0; +} |