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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2012 Rabin Vincent <rabin at rab.in>
*/
#include <linux/kernel.h>
#include <linux/stddef.h>
#include <linux/errno.h>
#include <linux/highmem.h>
#include <linux/sched.h>
#include <linux/uprobes.h>
#include <linux/notifier.h>
#include <asm/opcodes.h>
#include <asm/traps.h>
#include "../decode.h"
#include "../decode-arm.h"
#include "core.h"
#define UPROBE_TRAP_NR UINT_MAX
bool is_swbp_insn(uprobe_opcode_t *insn)
{
return (__mem_to_opcode_arm(*insn) & 0x0fffffff) ==
(UPROBE_SWBP_ARM_INSN & 0x0fffffff);
}
int set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm,
unsigned long vaddr)
{
return uprobe_write_opcode(auprobe, mm, vaddr,
__opcode_to_mem_arm(auprobe->bpinsn));
}
bool arch_uprobe_ignore(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
if (!auprobe->asi.insn_check_cc(regs->ARM_cpsr)) {
regs->ARM_pc += 4;
return true;
}
return false;
}
bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
probes_opcode_t opcode;
if (!auprobe->simulate)
return false;
opcode = __mem_to_opcode_arm(*(unsigned int *) auprobe->insn);
auprobe->asi.insn_singlestep(opcode, &auprobe->asi, regs);
return true;
}
unsigned long
arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr,
struct pt_regs *regs)
{
unsigned long orig_ret_vaddr;
orig_ret_vaddr = regs->ARM_lr;
/* Replace the return addr with trampoline addr */
regs->ARM_lr = trampoline_vaddr;
return orig_ret_vaddr;
}
int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
unsigned long addr)
{
unsigned int insn;
unsigned int bpinsn;
enum probes_insn ret;
/* Thumb not yet support */
if (addr & 0x3)
return -EINVAL;
insn = __mem_to_opcode_arm(*(unsigned int *)auprobe->insn);
auprobe->ixol[0] = __opcode_to_mem_arm(insn);
auprobe->ixol[1] = __opcode_to_mem_arm(UPROBE_SS_ARM_INSN);
ret = arm_probes_decode_insn(insn, &auprobe->asi, false,
uprobes_probes_actions, NULL);
switch (ret) {
case INSN_REJECTED:
return -EINVAL;
case INSN_GOOD_NO_SLOT:
auprobe->simulate = true;
break;
case INSN_GOOD:
default:
break;
}
bpinsn = UPROBE_SWBP_ARM_INSN & 0x0fffffff;
if (insn >= 0xe0000000)
bpinsn |= 0xe0000000; /* Unconditional instruction */
else
bpinsn |= insn & 0xf0000000; /* Copy condition from insn */
auprobe->bpinsn = bpinsn;
return 0;
}
void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
void *src, unsigned long len)
{
void *xol_page_kaddr = kmap_atomic(page);
void *dst = xol_page_kaddr + (vaddr & ~PAGE_MASK);
preempt_disable();
/* Initialize the slot */
memcpy(dst, src, len);
/* flush caches (dcache/icache) */
flush_uprobe_xol_access(page, vaddr, dst, len);
preempt_enable();
kunmap_atomic(xol_page_kaddr);
}
int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
struct uprobe_task *utask = current->utask;
if (auprobe->prehandler)
auprobe->prehandler(auprobe, &utask->autask, regs);
utask->autask.saved_trap_no = current->thread.trap_no;
current->thread.trap_no = UPROBE_TRAP_NR;
regs->ARM_pc = utask->xol_vaddr;
return 0;
}
int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
struct uprobe_task *utask = current->utask;
WARN_ON_ONCE(current->thread.trap_no != UPROBE_TRAP_NR);
current->thread.trap_no = utask->autask.saved_trap_no;
regs->ARM_pc = utask->vaddr + 4;
if (auprobe->posthandler)
auprobe->posthandler(auprobe, &utask->autask, regs);
return 0;
}
bool arch_uprobe_xol_was_trapped(struct task_struct *t)
{
if (t->thread.trap_no != UPROBE_TRAP_NR)
return true;
return false;
}
void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
struct uprobe_task *utask = current->utask;
current->thread.trap_no = utask->autask.saved_trap_no;
instruction_pointer_set(regs, utask->vaddr);
}
int arch_uprobe_exception_notify(struct notifier_block *self,
unsigned long val, void *data)
{
return NOTIFY_DONE;
}
static int uprobe_trap_handler(struct pt_regs *regs, unsigned int instr)
{
unsigned long flags;
local_irq_save(flags);
instr &= 0x0fffffff;
if (instr == (UPROBE_SWBP_ARM_INSN & 0x0fffffff))
uprobe_pre_sstep_notifier(regs);
else if (instr == (UPROBE_SS_ARM_INSN & 0x0fffffff))
uprobe_post_sstep_notifier(regs);
local_irq_restore(flags);
return 0;
}
unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
{
return instruction_pointer(regs);
}
static struct undef_hook uprobes_arm_break_hook = {
.instr_mask = 0x0fffffff,
.instr_val = (UPROBE_SWBP_ARM_INSN & 0x0fffffff),
.cpsr_mask = (PSR_T_BIT | MODE_MASK),
.cpsr_val = USR_MODE,
.fn = uprobe_trap_handler,
};
static struct undef_hook uprobes_arm_ss_hook = {
.instr_mask = 0x0fffffff,
.instr_val = (UPROBE_SS_ARM_INSN & 0x0fffffff),
.cpsr_mask = (PSR_T_BIT | MODE_MASK),
.cpsr_val = USR_MODE,
.fn = uprobe_trap_handler,
};
static int arch_uprobes_init(void)
{
register_undef_hook(&uprobes_arm_break_hook);
register_undef_hook(&uprobes_arm_ss_hook);
return 0;
}
device_initcall(arch_uprobes_init);
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