cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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traps.c (6251B)


      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Copyright (C) 2012 Regents of the University of California
      4 */
      5
      6#include <linux/cpu.h>
      7#include <linux/kernel.h>
      8#include <linux/init.h>
      9#include <linux/sched.h>
     10#include <linux/sched/debug.h>
     11#include <linux/sched/signal.h>
     12#include <linux/signal.h>
     13#include <linux/kdebug.h>
     14#include <linux/uaccess.h>
     15#include <linux/kprobes.h>
     16#include <linux/mm.h>
     17#include <linux/module.h>
     18#include <linux/irq.h>
     19
     20#include <asm/asm-prototypes.h>
     21#include <asm/bug.h>
     22#include <asm/processor.h>
     23#include <asm/ptrace.h>
     24#include <asm/csr.h>
     25
     26int show_unhandled_signals = 1;
     27
     28static DEFINE_SPINLOCK(die_lock);
     29
     30void die(struct pt_regs *regs, const char *str)
     31{
     32	static int die_counter;
     33	int ret;
     34
     35	oops_enter();
     36
     37	spin_lock_irq(&die_lock);
     38	console_verbose();
     39	bust_spinlocks(1);
     40
     41	pr_emerg("%s [#%d]\n", str, ++die_counter);
     42	print_modules();
     43	show_regs(regs);
     44
     45	ret = notify_die(DIE_OOPS, str, regs, 0, regs->cause, SIGSEGV);
     46
     47	bust_spinlocks(0);
     48	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
     49	spin_unlock_irq(&die_lock);
     50	oops_exit();
     51
     52	if (in_interrupt())
     53		panic("Fatal exception in interrupt");
     54	if (panic_on_oops)
     55		panic("Fatal exception");
     56	if (ret != NOTIFY_STOP)
     57		make_task_dead(SIGSEGV);
     58}
     59
     60void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr)
     61{
     62	struct task_struct *tsk = current;
     63
     64	if (show_unhandled_signals && unhandled_signal(tsk, signo)
     65	    && printk_ratelimit()) {
     66		pr_info("%s[%d]: unhandled signal %d code 0x%x at 0x" REG_FMT,
     67			tsk->comm, task_pid_nr(tsk), signo, code, addr);
     68		print_vma_addr(KERN_CONT " in ", instruction_pointer(regs));
     69		pr_cont("\n");
     70		__show_regs(regs);
     71	}
     72
     73	force_sig_fault(signo, code, (void __user *)addr);
     74}
     75
     76static void do_trap_error(struct pt_regs *regs, int signo, int code,
     77	unsigned long addr, const char *str)
     78{
     79	current->thread.bad_cause = regs->cause;
     80
     81	if (user_mode(regs)) {
     82		do_trap(regs, signo, code, addr);
     83	} else {
     84		if (!fixup_exception(regs))
     85			die(regs, str);
     86	}
     87}
     88
     89#if defined(CONFIG_XIP_KERNEL) && defined(CONFIG_RISCV_ALTERNATIVE)
     90#define __trap_section		__section(".xip.traps")
     91#else
     92#define __trap_section
     93#endif
     94#define DO_ERROR_INFO(name, signo, code, str)				\
     95asmlinkage __visible __trap_section void name(struct pt_regs *regs)	\
     96{									\
     97	do_trap_error(regs, signo, code, regs->epc, "Oops - " str);	\
     98}
     99
    100DO_ERROR_INFO(do_trap_unknown,
    101	SIGILL, ILL_ILLTRP, "unknown exception");
    102DO_ERROR_INFO(do_trap_insn_misaligned,
    103	SIGBUS, BUS_ADRALN, "instruction address misaligned");
    104DO_ERROR_INFO(do_trap_insn_fault,
    105	SIGSEGV, SEGV_ACCERR, "instruction access fault");
    106DO_ERROR_INFO(do_trap_insn_illegal,
    107	SIGILL, ILL_ILLOPC, "illegal instruction");
    108DO_ERROR_INFO(do_trap_load_fault,
    109	SIGSEGV, SEGV_ACCERR, "load access fault");
    110#ifndef CONFIG_RISCV_M_MODE
    111DO_ERROR_INFO(do_trap_load_misaligned,
    112	SIGBUS, BUS_ADRALN, "Oops - load address misaligned");
    113DO_ERROR_INFO(do_trap_store_misaligned,
    114	SIGBUS, BUS_ADRALN, "Oops - store (or AMO) address misaligned");
    115#else
    116int handle_misaligned_load(struct pt_regs *regs);
    117int handle_misaligned_store(struct pt_regs *regs);
    118
    119asmlinkage void __trap_section do_trap_load_misaligned(struct pt_regs *regs)
    120{
    121	if (!handle_misaligned_load(regs))
    122		return;
    123	do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
    124		      "Oops - load address misaligned");
    125}
    126
    127asmlinkage void __trap_section do_trap_store_misaligned(struct pt_regs *regs)
    128{
    129	if (!handle_misaligned_store(regs))
    130		return;
    131	do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
    132		      "Oops - store (or AMO) address misaligned");
    133}
    134#endif
    135DO_ERROR_INFO(do_trap_store_fault,
    136	SIGSEGV, SEGV_ACCERR, "store (or AMO) access fault");
    137DO_ERROR_INFO(do_trap_ecall_u,
    138	SIGILL, ILL_ILLTRP, "environment call from U-mode");
    139DO_ERROR_INFO(do_trap_ecall_s,
    140	SIGILL, ILL_ILLTRP, "environment call from S-mode");
    141DO_ERROR_INFO(do_trap_ecall_m,
    142	SIGILL, ILL_ILLTRP, "environment call from M-mode");
    143
    144static inline unsigned long get_break_insn_length(unsigned long pc)
    145{
    146	bug_insn_t insn;
    147
    148	if (get_kernel_nofault(insn, (bug_insn_t *)pc))
    149		return 0;
    150
    151	return GET_INSN_LENGTH(insn);
    152}
    153
    154asmlinkage __visible __trap_section void do_trap_break(struct pt_regs *regs)
    155{
    156#ifdef CONFIG_KPROBES
    157	if (kprobe_single_step_handler(regs))
    158		return;
    159
    160	if (kprobe_breakpoint_handler(regs))
    161		return;
    162#endif
    163#ifdef CONFIG_UPROBES
    164	if (uprobe_single_step_handler(regs))
    165		return;
    166
    167	if (uprobe_breakpoint_handler(regs))
    168		return;
    169#endif
    170	current->thread.bad_cause = regs->cause;
    171
    172	if (user_mode(regs))
    173		force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->epc);
    174#ifdef CONFIG_KGDB
    175	else if (notify_die(DIE_TRAP, "EBREAK", regs, 0, regs->cause, SIGTRAP)
    176								== NOTIFY_STOP)
    177		return;
    178#endif
    179	else if (report_bug(regs->epc, regs) == BUG_TRAP_TYPE_WARN)
    180		regs->epc += get_break_insn_length(regs->epc);
    181	else
    182		die(regs, "Kernel BUG");
    183}
    184NOKPROBE_SYMBOL(do_trap_break);
    185
    186#ifdef CONFIG_GENERIC_BUG
    187int is_valid_bugaddr(unsigned long pc)
    188{
    189	bug_insn_t insn;
    190
    191	if (pc < VMALLOC_START)
    192		return 0;
    193	if (get_kernel_nofault(insn, (bug_insn_t *)pc))
    194		return 0;
    195	if ((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32)
    196		return (insn == __BUG_INSN_32);
    197	else
    198		return ((insn & __COMPRESSED_INSN_MASK) == __BUG_INSN_16);
    199}
    200#endif /* CONFIG_GENERIC_BUG */
    201
    202#ifdef CONFIG_VMAP_STACK
    203static DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)],
    204		overflow_stack)__aligned(16);
    205/*
    206 * shadow stack, handled_ kernel_ stack_ overflow(in kernel/entry.S) is used
    207 * to get per-cpu overflow stack(get_overflow_stack).
    208 */
    209long shadow_stack[SHADOW_OVERFLOW_STACK_SIZE/sizeof(long)];
    210asmlinkage unsigned long get_overflow_stack(void)
    211{
    212	return (unsigned long)this_cpu_ptr(overflow_stack) +
    213		OVERFLOW_STACK_SIZE;
    214}
    215
    216asmlinkage void handle_bad_stack(struct pt_regs *regs)
    217{
    218	unsigned long tsk_stk = (unsigned long)current->stack;
    219	unsigned long ovf_stk = (unsigned long)this_cpu_ptr(overflow_stack);
    220
    221	console_verbose();
    222
    223	pr_emerg("Insufficient stack space to handle exception!\n");
    224	pr_emerg("Task stack:     [0x%016lx..0x%016lx]\n",
    225			tsk_stk, tsk_stk + THREAD_SIZE);
    226	pr_emerg("Overflow stack: [0x%016lx..0x%016lx]\n",
    227			ovf_stk, ovf_stk + OVERFLOW_STACK_SIZE);
    228
    229	__show_regs(regs);
    230	panic("Kernel stack overflow");
    231
    232	for (;;)
    233		wait_for_interrupt();
    234}
    235#endif