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463 lines
11 KiB
463 lines
11 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* |
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* Copyright (C) IBM Corporation, 2005 |
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* Jeff Muizelaar, 2006, 2007 |
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* Pekka Paalanen, 2008 <[email protected]> |
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* |
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* Derived from the read-mod example from relay-examples by Tom Zanussi. |
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*/ |
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#define pr_fmt(fmt) "mmiotrace: " fmt |
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#include <linux/moduleparam.h> |
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#include <linux/debugfs.h> |
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#include <linux/slab.h> |
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#include <linux/uaccess.h> |
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#include <linux/io.h> |
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#include <linux/mmiotrace.h> |
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#include <linux/pgtable.h> |
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#include <asm/e820/api.h> /* for ISA_START_ADDRESS */ |
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#include <linux/atomic.h> |
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#include <linux/percpu.h> |
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#include <linux/cpu.h> |
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#include "pf_in.h" |
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struct trap_reason { |
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unsigned long addr; |
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unsigned long ip; |
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enum reason_type type; |
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int active_traces; |
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}; |
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struct remap_trace { |
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struct list_head list; |
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struct kmmio_probe probe; |
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resource_size_t phys; |
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unsigned long id; |
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}; |
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/* Accessed per-cpu. */ |
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static DEFINE_PER_CPU(struct trap_reason, pf_reason); |
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static DEFINE_PER_CPU(struct mmiotrace_rw, cpu_trace); |
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static DEFINE_MUTEX(mmiotrace_mutex); |
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static DEFINE_SPINLOCK(trace_lock); |
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static atomic_t mmiotrace_enabled; |
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static LIST_HEAD(trace_list); /* struct remap_trace */ |
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/* |
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* Locking in this file: |
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* - mmiotrace_mutex enforces enable/disable_mmiotrace() critical sections. |
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* - mmiotrace_enabled may be modified only when holding mmiotrace_mutex |
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* and trace_lock. |
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* - Routines depending on is_enabled() must take trace_lock. |
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* - trace_list users must hold trace_lock. |
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* - is_enabled() guarantees that mmio_trace_{rw,mapping} are allowed. |
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* - pre/post callbacks assume the effect of is_enabled() being true. |
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*/ |
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/* module parameters */ |
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static unsigned long filter_offset; |
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static bool nommiotrace; |
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static bool trace_pc; |
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module_param(filter_offset, ulong, 0); |
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module_param(nommiotrace, bool, 0); |
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module_param(trace_pc, bool, 0); |
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MODULE_PARM_DESC(filter_offset, "Start address of traced mappings."); |
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MODULE_PARM_DESC(nommiotrace, "Disable actual MMIO tracing."); |
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MODULE_PARM_DESC(trace_pc, "Record address of faulting instructions."); |
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static bool is_enabled(void) |
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{ |
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return atomic_read(&mmiotrace_enabled); |
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} |
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static void print_pte(unsigned long address) |
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{ |
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unsigned int level; |
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pte_t *pte = lookup_address(address, &level); |
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if (!pte) { |
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pr_err("Error in %s: no pte for page 0x%08lx\n", |
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__func__, address); |
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return; |
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} |
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if (level == PG_LEVEL_2M) { |
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pr_emerg("4MB pages are not currently supported: 0x%08lx\n", |
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address); |
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BUG(); |
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} |
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pr_info("pte for 0x%lx: 0x%llx 0x%llx\n", |
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address, |
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(unsigned long long)pte_val(*pte), |
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(unsigned long long)pte_val(*pte) & _PAGE_PRESENT); |
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} |
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/* |
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* For some reason the pre/post pairs have been called in an |
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* unmatched order. Report and die. |
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*/ |
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static void die_kmmio_nesting_error(struct pt_regs *regs, unsigned long addr) |
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{ |
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const struct trap_reason *my_reason = &get_cpu_var(pf_reason); |
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pr_emerg("unexpected fault for address: 0x%08lx, last fault for address: 0x%08lx\n", |
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addr, my_reason->addr); |
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print_pte(addr); |
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pr_emerg("faulting IP is at %pS\n", (void *)regs->ip); |
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pr_emerg("last faulting IP was at %pS\n", (void *)my_reason->ip); |
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#ifdef __i386__ |
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pr_emerg("eax: %08lx ebx: %08lx ecx: %08lx edx: %08lx\n", |
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regs->ax, regs->bx, regs->cx, regs->dx); |
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pr_emerg("esi: %08lx edi: %08lx ebp: %08lx esp: %08lx\n", |
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regs->si, regs->di, regs->bp, regs->sp); |
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#else |
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pr_emerg("rax: %016lx rcx: %016lx rdx: %016lx\n", |
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regs->ax, regs->cx, regs->dx); |
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pr_emerg("rsi: %016lx rdi: %016lx rbp: %016lx rsp: %016lx\n", |
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regs->si, regs->di, regs->bp, regs->sp); |
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#endif |
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put_cpu_var(pf_reason); |
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BUG(); |
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} |
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static void pre(struct kmmio_probe *p, struct pt_regs *regs, |
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unsigned long addr) |
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{ |
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struct trap_reason *my_reason = &get_cpu_var(pf_reason); |
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struct mmiotrace_rw *my_trace = &get_cpu_var(cpu_trace); |
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const unsigned long instptr = instruction_pointer(regs); |
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const enum reason_type type = get_ins_type(instptr); |
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struct remap_trace *trace = p->private; |
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/* it doesn't make sense to have more than one active trace per cpu */ |
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if (my_reason->active_traces) |
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die_kmmio_nesting_error(regs, addr); |
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else |
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my_reason->active_traces++; |
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my_reason->type = type; |
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my_reason->addr = addr; |
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my_reason->ip = instptr; |
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my_trace->phys = addr - trace->probe.addr + trace->phys; |
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my_trace->map_id = trace->id; |
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/* |
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* Only record the program counter when requested. |
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* It may taint clean-room reverse engineering. |
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*/ |
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if (trace_pc) |
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my_trace->pc = instptr; |
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else |
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my_trace->pc = 0; |
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/* |
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* XXX: the timestamp recorded will be *after* the tracing has been |
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* done, not at the time we hit the instruction. SMP implications |
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* on event ordering? |
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*/ |
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switch (type) { |
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case REG_READ: |
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my_trace->opcode = MMIO_READ; |
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my_trace->width = get_ins_mem_width(instptr); |
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break; |
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case REG_WRITE: |
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my_trace->opcode = MMIO_WRITE; |
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my_trace->width = get_ins_mem_width(instptr); |
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my_trace->value = get_ins_reg_val(instptr, regs); |
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break; |
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case IMM_WRITE: |
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my_trace->opcode = MMIO_WRITE; |
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my_trace->width = get_ins_mem_width(instptr); |
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my_trace->value = get_ins_imm_val(instptr); |
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break; |
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default: |
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{ |
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unsigned char *ip = (unsigned char *)instptr; |
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my_trace->opcode = MMIO_UNKNOWN_OP; |
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my_trace->width = 0; |
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my_trace->value = (*ip) << 16 | *(ip + 1) << 8 | |
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*(ip + 2); |
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} |
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} |
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put_cpu_var(cpu_trace); |
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put_cpu_var(pf_reason); |
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} |
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static void post(struct kmmio_probe *p, unsigned long condition, |
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struct pt_regs *regs) |
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{ |
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struct trap_reason *my_reason = &get_cpu_var(pf_reason); |
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struct mmiotrace_rw *my_trace = &get_cpu_var(cpu_trace); |
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/* this should always return the active_trace count to 0 */ |
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my_reason->active_traces--; |
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if (my_reason->active_traces) { |
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pr_emerg("unexpected post handler"); |
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BUG(); |
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} |
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switch (my_reason->type) { |
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case REG_READ: |
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my_trace->value = get_ins_reg_val(my_reason->ip, regs); |
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break; |
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default: |
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break; |
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} |
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mmio_trace_rw(my_trace); |
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put_cpu_var(cpu_trace); |
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put_cpu_var(pf_reason); |
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} |
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static void ioremap_trace_core(resource_size_t offset, unsigned long size, |
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void __iomem *addr) |
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{ |
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static atomic_t next_id; |
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struct remap_trace *trace = kmalloc(sizeof(*trace), GFP_KERNEL); |
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/* These are page-unaligned. */ |
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struct mmiotrace_map map = { |
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.phys = offset, |
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.virt = (unsigned long)addr, |
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.len = size, |
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.opcode = MMIO_PROBE |
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}; |
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if (!trace) { |
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pr_err("kmalloc failed in ioremap\n"); |
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return; |
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} |
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*trace = (struct remap_trace) { |
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.probe = { |
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.addr = (unsigned long)addr, |
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.len = size, |
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.pre_handler = pre, |
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.post_handler = post, |
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.private = trace |
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}, |
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.phys = offset, |
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.id = atomic_inc_return(&next_id) |
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}; |
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map.map_id = trace->id; |
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spin_lock_irq(&trace_lock); |
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if (!is_enabled()) { |
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kfree(trace); |
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goto not_enabled; |
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} |
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mmio_trace_mapping(&map); |
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list_add_tail(&trace->list, &trace_list); |
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if (!nommiotrace) |
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register_kmmio_probe(&trace->probe); |
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not_enabled: |
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spin_unlock_irq(&trace_lock); |
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} |
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void mmiotrace_ioremap(resource_size_t offset, unsigned long size, |
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void __iomem *addr) |
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{ |
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if (!is_enabled()) /* recheck and proper locking in *_core() */ |
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return; |
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pr_debug("ioremap_*(0x%llx, 0x%lx) = %p\n", |
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(unsigned long long)offset, size, addr); |
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if ((filter_offset) && (offset != filter_offset)) |
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return; |
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ioremap_trace_core(offset, size, addr); |
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} |
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static void iounmap_trace_core(volatile void __iomem *addr) |
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{ |
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struct mmiotrace_map map = { |
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.phys = 0, |
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.virt = (unsigned long)addr, |
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.len = 0, |
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.opcode = MMIO_UNPROBE |
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}; |
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struct remap_trace *trace; |
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struct remap_trace *tmp; |
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struct remap_trace *found_trace = NULL; |
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pr_debug("Unmapping %p.\n", addr); |
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spin_lock_irq(&trace_lock); |
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if (!is_enabled()) |
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goto not_enabled; |
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list_for_each_entry_safe(trace, tmp, &trace_list, list) { |
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if ((unsigned long)addr == trace->probe.addr) { |
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if (!nommiotrace) |
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unregister_kmmio_probe(&trace->probe); |
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list_del(&trace->list); |
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found_trace = trace; |
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break; |
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} |
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} |
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map.map_id = (found_trace) ? found_trace->id : -1; |
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mmio_trace_mapping(&map); |
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not_enabled: |
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spin_unlock_irq(&trace_lock); |
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if (found_trace) { |
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synchronize_rcu(); /* unregister_kmmio_probe() requirement */ |
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kfree(found_trace); |
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} |
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} |
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void mmiotrace_iounmap(volatile void __iomem *addr) |
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{ |
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might_sleep(); |
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if (is_enabled()) /* recheck and proper locking in *_core() */ |
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iounmap_trace_core(addr); |
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} |
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int mmiotrace_printk(const char *fmt, ...) |
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{ |
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int ret = 0; |
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va_list args; |
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unsigned long flags; |
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va_start(args, fmt); |
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spin_lock_irqsave(&trace_lock, flags); |
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if (is_enabled()) |
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ret = mmio_trace_printk(fmt, args); |
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spin_unlock_irqrestore(&trace_lock, flags); |
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va_end(args); |
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return ret; |
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} |
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EXPORT_SYMBOL(mmiotrace_printk); |
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static void clear_trace_list(void) |
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{ |
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struct remap_trace *trace; |
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struct remap_trace *tmp; |
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/* |
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* No locking required, because the caller ensures we are in a |
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* critical section via mutex, and is_enabled() is false, |
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* i.e. nothing can traverse or modify this list. |
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* Caller also ensures is_enabled() cannot change. |
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*/ |
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list_for_each_entry(trace, &trace_list, list) { |
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pr_notice("purging non-iounmapped trace @0x%08lx, size 0x%lx.\n", |
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trace->probe.addr, trace->probe.len); |
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if (!nommiotrace) |
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unregister_kmmio_probe(&trace->probe); |
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} |
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synchronize_rcu(); /* unregister_kmmio_probe() requirement */ |
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list_for_each_entry_safe(trace, tmp, &trace_list, list) { |
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list_del(&trace->list); |
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kfree(trace); |
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} |
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} |
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#ifdef CONFIG_HOTPLUG_CPU |
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static cpumask_var_t downed_cpus; |
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static void enter_uniprocessor(void) |
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{ |
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int cpu; |
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int err; |
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if (!cpumask_available(downed_cpus) && |
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!alloc_cpumask_var(&downed_cpus, GFP_KERNEL)) { |
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pr_notice("Failed to allocate mask\n"); |
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goto out; |
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} |
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get_online_cpus(); |
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cpumask_copy(downed_cpus, cpu_online_mask); |
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cpumask_clear_cpu(cpumask_first(cpu_online_mask), downed_cpus); |
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if (num_online_cpus() > 1) |
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pr_notice("Disabling non-boot CPUs...\n"); |
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put_online_cpus(); |
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for_each_cpu(cpu, downed_cpus) { |
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err = remove_cpu(cpu); |
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if (!err) |
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pr_info("CPU%d is down.\n", cpu); |
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else |
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pr_err("Error taking CPU%d down: %d\n", cpu, err); |
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} |
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out: |
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if (num_online_cpus() > 1) |
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pr_warn("multiple CPUs still online, may miss events.\n"); |
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} |
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static void leave_uniprocessor(void) |
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{ |
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int cpu; |
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int err; |
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if (!cpumask_available(downed_cpus) || cpumask_weight(downed_cpus) == 0) |
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return; |
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pr_notice("Re-enabling CPUs...\n"); |
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for_each_cpu(cpu, downed_cpus) { |
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err = add_cpu(cpu); |
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if (!err) |
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pr_info("enabled CPU%d.\n", cpu); |
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else |
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pr_err("cannot re-enable CPU%d: %d\n", cpu, err); |
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} |
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} |
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#else /* !CONFIG_HOTPLUG_CPU */ |
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static void enter_uniprocessor(void) |
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{ |
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if (num_online_cpus() > 1) |
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pr_warn("multiple CPUs are online, may miss events. " |
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"Suggest booting with maxcpus=1 kernel argument.\n"); |
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} |
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static void leave_uniprocessor(void) |
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{ |
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} |
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#endif |
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void enable_mmiotrace(void) |
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{ |
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mutex_lock(&mmiotrace_mutex); |
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if (is_enabled()) |
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goto out; |
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if (nommiotrace) |
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pr_info("MMIO tracing disabled.\n"); |
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kmmio_init(); |
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enter_uniprocessor(); |
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spin_lock_irq(&trace_lock); |
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atomic_inc(&mmiotrace_enabled); |
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spin_unlock_irq(&trace_lock); |
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pr_info("enabled.\n"); |
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out: |
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mutex_unlock(&mmiotrace_mutex); |
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} |
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void disable_mmiotrace(void) |
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{ |
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mutex_lock(&mmiotrace_mutex); |
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if (!is_enabled()) |
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goto out; |
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spin_lock_irq(&trace_lock); |
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atomic_dec(&mmiotrace_enabled); |
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BUG_ON(is_enabled()); |
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spin_unlock_irq(&trace_lock); |
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clear_trace_list(); /* guarantees: no more kmmio callbacks */ |
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leave_uniprocessor(); |
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kmmio_cleanup(); |
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pr_info("disabled.\n"); |
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out: |
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mutex_unlock(&mmiotrace_mutex); |
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}
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