forked from luck/tmp_suning_uos_patched
b74ab703b1
Presently the hw_breakpoint code is the primary notifier dispatch for breakpoint traps, although it's only UBC traps that are of particular interest there. This patches in a check to allow non-UBC generated breakpoints to pass through down the remainder of the notifier chain, giving things like kgdb a chance at getting notified. Signed-off-by: Paul Mundt <lethal@linux-sh.org>
425 lines
8.5 KiB
C
425 lines
8.5 KiB
C
/*
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* arch/sh/kernel/hw_breakpoint.c
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*
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* Unified kernel/user-space hardware breakpoint facility for the on-chip UBC.
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*
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* Copyright (C) 2009 Paul Mundt
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*/
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#include <linux/init.h>
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#include <linux/perf_event.h>
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#include <linux/hw_breakpoint.h>
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#include <linux/percpu.h>
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#include <linux/kallsyms.h>
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#include <linux/notifier.h>
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#include <linux/kprobes.h>
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#include <linux/kdebug.h>
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#include <linux/io.h>
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#include <asm/hw_breakpoint.h>
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#include <asm/mmu_context.h>
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struct ubc_context {
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unsigned long pc;
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unsigned long state;
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};
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/* Per cpu ubc channel state */
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static DEFINE_PER_CPU(struct ubc_context, ubc_ctx[HBP_NUM]);
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/*
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* Stores the breakpoints currently in use on each breakpoint address
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* register for each cpus
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*/
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static DEFINE_PER_CPU(struct perf_event *, bp_per_reg[HBP_NUM]);
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static int __init ubc_init(void)
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{
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__raw_writel(0, UBC_CAMR0);
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__raw_writel(0, UBC_CBR0);
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__raw_writel(0, UBC_CBCR);
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__raw_writel(UBC_CRR_BIE | UBC_CRR_PCB, UBC_CRR0);
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/* dummy read for write posting */
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(void)__raw_readl(UBC_CRR0);
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return 0;
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}
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arch_initcall(ubc_init);
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/*
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* Install a perf counter breakpoint.
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*
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* We seek a free UBC channel and use it for this breakpoint.
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*
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* Atomic: we hold the counter->ctx->lock and we only handle variables
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* and registers local to this cpu.
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*/
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int arch_install_hw_breakpoint(struct perf_event *bp)
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{
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struct arch_hw_breakpoint *info = counter_arch_bp(bp);
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struct ubc_context *ubc_ctx;
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int i;
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for (i = 0; i < HBP_NUM; i++) {
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struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]);
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if (!*slot) {
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*slot = bp;
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break;
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}
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}
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if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot"))
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return -EBUSY;
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ubc_ctx = &__get_cpu_var(ubc_ctx[i]);
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ubc_ctx->pc = info->address;
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ubc_ctx->state = info->len | info->type;
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__raw_writel(UBC_CBR_CE | ubc_ctx->state, UBC_CBR0);
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__raw_writel(ubc_ctx->pc, UBC_CAR0);
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return 0;
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}
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/*
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* Uninstall the breakpoint contained in the given counter.
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*
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* First we search the debug address register it uses and then we disable
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* it.
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*
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* Atomic: we hold the counter->ctx->lock and we only handle variables
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* and registers local to this cpu.
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*/
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void arch_uninstall_hw_breakpoint(struct perf_event *bp)
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{
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struct arch_hw_breakpoint *info = counter_arch_bp(bp);
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struct ubc_context *ubc_ctx;
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int i;
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for (i = 0; i < HBP_NUM; i++) {
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struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]);
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if (*slot == bp) {
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*slot = NULL;
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break;
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}
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}
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if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot"))
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return;
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ubc_ctx = &__get_cpu_var(ubc_ctx[i]);
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ubc_ctx->pc = 0;
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ubc_ctx->state &= ~(info->len | info->type);
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__raw_writel(ubc_ctx->pc, UBC_CBR0);
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__raw_writel(ubc_ctx->state, UBC_CAR0);
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}
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static int get_hbp_len(u16 hbp_len)
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{
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unsigned int len_in_bytes = 0;
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switch (hbp_len) {
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case SH_BREAKPOINT_LEN_1:
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len_in_bytes = 1;
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break;
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case SH_BREAKPOINT_LEN_2:
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len_in_bytes = 2;
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break;
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case SH_BREAKPOINT_LEN_4:
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len_in_bytes = 4;
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break;
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case SH_BREAKPOINT_LEN_8:
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len_in_bytes = 8;
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break;
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}
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return len_in_bytes;
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}
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/*
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* Check for virtual address in user space.
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*/
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int arch_check_va_in_userspace(unsigned long va, u16 hbp_len)
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{
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unsigned int len;
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len = get_hbp_len(hbp_len);
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return (va <= TASK_SIZE - len);
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}
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/*
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* Check for virtual address in kernel space.
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*/
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static int arch_check_va_in_kernelspace(unsigned long va, u8 hbp_len)
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{
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unsigned int len;
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len = get_hbp_len(hbp_len);
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return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
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}
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/*
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* Store a breakpoint's encoded address, length, and type.
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*/
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static int arch_store_info(struct perf_event *bp)
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{
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struct arch_hw_breakpoint *info = counter_arch_bp(bp);
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/*
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* User-space requests will always have the address field populated
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* For kernel-addresses, either the address or symbol name can be
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* specified.
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*/
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if (info->name)
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info->address = (unsigned long)kallsyms_lookup_name(info->name);
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if (info->address) {
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info->asid = get_asid();
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return 0;
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}
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return -EINVAL;
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}
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int arch_bp_generic_fields(int sh_len, int sh_type,
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int *gen_len, int *gen_type)
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{
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/* Len */
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switch (sh_len) {
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case SH_BREAKPOINT_LEN_1:
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*gen_len = HW_BREAKPOINT_LEN_1;
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break;
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case SH_BREAKPOINT_LEN_2:
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*gen_len = HW_BREAKPOINT_LEN_2;
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break;
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case SH_BREAKPOINT_LEN_4:
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*gen_len = HW_BREAKPOINT_LEN_4;
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break;
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case SH_BREAKPOINT_LEN_8:
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*gen_len = HW_BREAKPOINT_LEN_8;
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break;
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default:
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return -EINVAL;
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}
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/* Type */
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switch (sh_type) {
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case SH_BREAKPOINT_READ:
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*gen_type = HW_BREAKPOINT_R;
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case SH_BREAKPOINT_WRITE:
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*gen_type = HW_BREAKPOINT_W;
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break;
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case SH_BREAKPOINT_RW:
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*gen_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;
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break;
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default:
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return -EINVAL;
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}
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return 0;
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}
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static int arch_build_bp_info(struct perf_event *bp)
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{
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struct arch_hw_breakpoint *info = counter_arch_bp(bp);
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info->address = bp->attr.bp_addr;
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/* Len */
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switch (bp->attr.bp_len) {
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case HW_BREAKPOINT_LEN_1:
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info->len = SH_BREAKPOINT_LEN_1;
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break;
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case HW_BREAKPOINT_LEN_2:
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info->len = SH_BREAKPOINT_LEN_2;
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break;
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case HW_BREAKPOINT_LEN_4:
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info->len = SH_BREAKPOINT_LEN_4;
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break;
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case HW_BREAKPOINT_LEN_8:
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info->len = SH_BREAKPOINT_LEN_8;
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break;
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default:
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return -EINVAL;
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}
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/* Type */
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switch (bp->attr.bp_type) {
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case HW_BREAKPOINT_R:
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info->type = SH_BREAKPOINT_READ;
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break;
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case HW_BREAKPOINT_W:
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info->type = SH_BREAKPOINT_WRITE;
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break;
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case HW_BREAKPOINT_W | HW_BREAKPOINT_R:
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info->type = SH_BREAKPOINT_RW;
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break;
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default:
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return -EINVAL;
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}
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return 0;
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}
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/*
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* Validate the arch-specific HW Breakpoint register settings
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*/
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int arch_validate_hwbkpt_settings(struct perf_event *bp,
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struct task_struct *tsk)
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{
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struct arch_hw_breakpoint *info = counter_arch_bp(bp);
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unsigned int align;
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int ret;
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ret = arch_build_bp_info(bp);
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if (ret)
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return ret;
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ret = -EINVAL;
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switch (info->len) {
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case SH_BREAKPOINT_LEN_1:
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align = 0;
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break;
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case SH_BREAKPOINT_LEN_2:
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align = 1;
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break;
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case SH_BREAKPOINT_LEN_4:
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align = 3;
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break;
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case SH_BREAKPOINT_LEN_8:
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align = 7;
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break;
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default:
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return ret;
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}
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ret = arch_store_info(bp);
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if (ret < 0)
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return ret;
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/*
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* Check that the low-order bits of the address are appropriate
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* for the alignment implied by len.
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*/
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if (info->address & align)
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return -EINVAL;
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/* Check that the virtual address is in the proper range */
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if (tsk) {
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if (!arch_check_va_in_userspace(info->address, info->len))
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return -EFAULT;
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} else {
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if (!arch_check_va_in_kernelspace(info->address, info->len))
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return -EFAULT;
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}
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return 0;
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}
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/*
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* Release the user breakpoints used by ptrace
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*/
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void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
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{
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int i;
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struct thread_struct *t = &tsk->thread;
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for (i = 0; i < HBP_NUM; i++) {
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unregister_hw_breakpoint(t->ptrace_bps[i]);
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t->ptrace_bps[i] = NULL;
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}
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}
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static int __kprobes hw_breakpoint_handler(struct die_args *args)
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{
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int cpu, i, rc = NOTIFY_STOP;
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struct perf_event *bp;
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unsigned long val;
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val = __raw_readl(UBC_CBR0);
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__raw_writel(val & ~UBC_CBR_CE, UBC_CBR0);
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cpu = get_cpu();
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for (i = 0; i < HBP_NUM; i++) {
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/*
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* The counter may be concurrently released but that can only
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* occur from a call_rcu() path. We can then safely fetch
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* the breakpoint, use its callback, touch its counter
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* while we are in an rcu_read_lock() path.
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*/
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rcu_read_lock();
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bp = per_cpu(bp_per_reg[i], cpu);
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if (bp) {
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rc = NOTIFY_DONE;
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} else {
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rcu_read_unlock();
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break;
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}
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perf_bp_event(bp, args->regs);
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rcu_read_unlock();
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}
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if (bp) {
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struct arch_hw_breakpoint *info = counter_arch_bp(bp);
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__raw_writel(UBC_CBR_CE | info->len | info->type, UBC_CBR0);
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__raw_writel(info->address, UBC_CAR0);
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}
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put_cpu();
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return rc;
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}
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BUILD_TRAP_HANDLER(breakpoint)
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{
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unsigned long ex = lookup_exception_vector();
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TRAP_HANDLER_DECL;
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notify_die(DIE_BREAKPOINT, "breakpoint", regs, 0, ex, SIGTRAP);
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}
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/*
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* Handle debug exception notifications.
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*/
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int __kprobes hw_breakpoint_exceptions_notify(struct notifier_block *unused,
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unsigned long val, void *data)
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{
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struct die_args *args = data;
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if (val != DIE_BREAKPOINT)
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return NOTIFY_DONE;
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/*
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* If the breakpoint hasn't been triggered by the UBC, it's
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* probably from a debugger, so don't do anything more here.
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*/
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if (args->trapnr != 0x1e0)
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return NOTIFY_DONE;
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return hw_breakpoint_handler(data);
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}
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void hw_breakpoint_pmu_read(struct perf_event *bp)
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{
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/* TODO */
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}
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void hw_breakpoint_pmu_unthrottle(struct perf_event *bp)
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{
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/* TODO */
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}
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