diff options
Diffstat (limited to 'arch/arm64/kernel/traps.c')
| -rw-r--r-- | arch/arm64/kernel/traps.c | 997 |
1 files changed, 997 insertions, 0 deletions
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c new file mode 100644 index 000000000..10a58017d --- /dev/null +++ b/arch/arm64/kernel/traps.c @@ -0,0 +1,997 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Based on arch/arm/kernel/traps.c + * + * Copyright (C) 1995-2009 Russell King + * Copyright (C) 2012 ARM Ltd. + */ + +#include <linux/bug.h> +#include <linux/context_tracking.h> +#include <linux/signal.h> +#include <linux/personality.h> +#include <linux/kallsyms.h> +#include <linux/kprobes.h> +#include <linux/spinlock.h> +#include <linux/uaccess.h> +#include <linux/hardirq.h> +#include <linux/kdebug.h> +#include <linux/module.h> +#include <linux/kexec.h> +#include <linux/delay.h> +#include <linux/init.h> +#include <linux/sched/signal.h> +#include <linux/sched/debug.h> +#include <linux/sched/task_stack.h> +#include <linux/sizes.h> +#include <linux/syscalls.h> +#include <linux/mm_types.h> +#include <linux/kasan.h> + +#include <asm/atomic.h> +#include <asm/bug.h> +#include <asm/cpufeature.h> +#include <asm/daifflags.h> +#include <asm/debug-monitors.h> +#include <asm/esr.h> +#include <asm/exception.h> +#include <asm/extable.h> +#include <asm/insn.h> +#include <asm/kprobes.h> +#include <asm/traps.h> +#include <asm/smp.h> +#include <asm/stack_pointer.h> +#include <asm/stacktrace.h> +#include <asm/exception.h> +#include <asm/system_misc.h> +#include <asm/sysreg.h> + +static const char *handler[]= { + "Synchronous Abort", + "IRQ", + "FIQ", + "Error" +}; + +int show_unhandled_signals = 0; + +static void dump_kernel_instr(const char *lvl, struct pt_regs *regs) +{ + unsigned long addr = instruction_pointer(regs); + char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str; + int i; + + if (user_mode(regs)) + return; + + for (i = -4; i < 1; i++) { + unsigned int val, bad; + + bad = aarch64_insn_read(&((u32 *)addr)[i], &val); + + if (!bad) + p += sprintf(p, i == 0 ? "(%08x) " : "%08x ", val); + else { + p += sprintf(p, "bad PC value"); + break; + } + } + + printk("%sCode: %s\n", lvl, str); +} + +#ifdef CONFIG_PREEMPT +#define S_PREEMPT " PREEMPT" +#elif defined(CONFIG_PREEMPT_RT) +#define S_PREEMPT " PREEMPT_RT" +#else +#define S_PREEMPT "" +#endif + +#define S_SMP " SMP" + +static int __die(const char *str, long err, struct pt_regs *regs) +{ + static int die_counter; + int ret; + + pr_emerg("Internal error: %s: %016lx [#%d]" S_PREEMPT S_SMP "\n", + str, err, ++die_counter); + + /* trap and error numbers are mostly meaningless on ARM */ + ret = notify_die(DIE_OOPS, str, regs, err, 0, SIGSEGV); + if (ret == NOTIFY_STOP) + return ret; + + print_modules(); + show_regs(regs); + + dump_kernel_instr(KERN_EMERG, regs); + + return ret; +} + +static DEFINE_RAW_SPINLOCK(die_lock); + +/* + * This function is protected against re-entrancy. + */ +void die(const char *str, struct pt_regs *regs, long err) +{ + int ret; + unsigned long flags; + + raw_spin_lock_irqsave(&die_lock, flags); + + oops_enter(); + + console_verbose(); + bust_spinlocks(1); + ret = __die(str, err, regs); + + if (regs && kexec_should_crash(current)) + crash_kexec(regs); + + bust_spinlocks(0); + add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); + oops_exit(); + + if (in_interrupt()) + panic("%s: Fatal exception in interrupt", str); + if (panic_on_oops) + panic("%s: Fatal exception", str); + + raw_spin_unlock_irqrestore(&die_lock, flags); + + if (ret != NOTIFY_STOP) + make_task_dead(SIGSEGV); +} + +static void arm64_show_signal(int signo, const char *str) +{ + static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL, + DEFAULT_RATELIMIT_BURST); + struct task_struct *tsk = current; + unsigned int esr = tsk->thread.fault_code; + struct pt_regs *regs = task_pt_regs(tsk); + + /* Leave if the signal won't be shown */ + if (!show_unhandled_signals || + !unhandled_signal(tsk, signo) || + !__ratelimit(&rs)) + return; + + pr_info("%s[%d]: unhandled exception: ", tsk->comm, task_pid_nr(tsk)); + if (esr) + pr_cont("%s, ESR 0x%08x, ", esr_get_class_string(esr), esr); + + pr_cont("%s", str); + print_vma_addr(KERN_CONT " in ", regs->pc); + pr_cont("\n"); + __show_regs(regs); +} + +void arm64_force_sig_fault(int signo, int code, void __user *addr, + const char *str) +{ + arm64_show_signal(signo, str); + if (signo == SIGKILL) + force_sig(SIGKILL); + else + force_sig_fault(signo, code, addr); +} + +void arm64_force_sig_mceerr(int code, void __user *addr, short lsb, + const char *str) +{ + arm64_show_signal(SIGBUS, str); + force_sig_mceerr(code, addr, lsb); +} + +void arm64_force_sig_ptrace_errno_trap(int errno, void __user *addr, + const char *str) +{ + arm64_show_signal(SIGTRAP, str); + force_sig_ptrace_errno_trap(errno, addr); +} + +void arm64_notify_die(const char *str, struct pt_regs *regs, + int signo, int sicode, void __user *addr, + int err) +{ + if (user_mode(regs)) { + WARN_ON(regs != current_pt_regs()); + current->thread.fault_address = 0; + current->thread.fault_code = err; + + arm64_force_sig_fault(signo, sicode, addr, str); + } else { + die(str, regs, err); + } +} + +#ifdef CONFIG_COMPAT +#define PSTATE_IT_1_0_SHIFT 25 +#define PSTATE_IT_1_0_MASK (0x3 << PSTATE_IT_1_0_SHIFT) +#define PSTATE_IT_7_2_SHIFT 10 +#define PSTATE_IT_7_2_MASK (0x3f << PSTATE_IT_7_2_SHIFT) + +static u32 compat_get_it_state(struct pt_regs *regs) +{ + u32 it, pstate = regs->pstate; + + it = (pstate & PSTATE_IT_1_0_MASK) >> PSTATE_IT_1_0_SHIFT; + it |= ((pstate & PSTATE_IT_7_2_MASK) >> PSTATE_IT_7_2_SHIFT) << 2; + + return it; +} + +static void compat_set_it_state(struct pt_regs *regs, u32 it) +{ + u32 pstate_it; + + pstate_it = (it << PSTATE_IT_1_0_SHIFT) & PSTATE_IT_1_0_MASK; + pstate_it |= ((it >> 2) << PSTATE_IT_7_2_SHIFT) & PSTATE_IT_7_2_MASK; + + regs->pstate &= ~PSR_AA32_IT_MASK; + regs->pstate |= pstate_it; +} + +static void advance_itstate(struct pt_regs *regs) +{ + u32 it; + + /* ARM mode */ + if (!(regs->pstate & PSR_AA32_T_BIT) || + !(regs->pstate & PSR_AA32_IT_MASK)) + return; + + it = compat_get_it_state(regs); + + /* + * If this is the last instruction of the block, wipe the IT + * state. Otherwise advance it. + */ + if (!(it & 7)) + it = 0; + else + it = (it & 0xe0) | ((it << 1) & 0x1f); + + compat_set_it_state(regs, it); +} +#else +static void advance_itstate(struct pt_regs *regs) +{ +} +#endif + +void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size) +{ + regs->pc += size; + + /* + * If we were single stepping, we want to get the step exception after + * we return from the trap. + */ + if (user_mode(regs)) + user_fastforward_single_step(current); + + if (compat_user_mode(regs)) + advance_itstate(regs); + else + regs->pstate &= ~PSR_BTYPE_MASK; +} + +static int user_insn_read(struct pt_regs *regs, u32 *insnp) +{ + u32 instr; + void __user *pc = (void __user *)instruction_pointer(regs); + + if (compat_thumb_mode(regs)) { + /* 16-bit Thumb instruction */ + __le16 instr_le; + if (get_user(instr_le, (__le16 __user *)pc)) + return -EFAULT; + instr = le16_to_cpu(instr_le); + if (aarch32_insn_is_wide(instr)) { + u32 instr2; + + if (get_user(instr_le, (__le16 __user *)(pc + 2))) + return -EFAULT; + instr2 = le16_to_cpu(instr_le); + instr = (instr << 16) | instr2; + } + } else { + /* 32-bit ARM instruction */ + __le32 instr_le; + if (get_user(instr_le, (__le32 __user *)pc)) + return -EFAULT; + instr = le32_to_cpu(instr_le); + } + + *insnp = instr; + return 0; +} + +void force_signal_inject(int signal, int code, unsigned long address, unsigned int err) +{ + const char *desc; + struct pt_regs *regs = current_pt_regs(); + + if (WARN_ON(!user_mode(regs))) + return; + + switch (signal) { + case SIGILL: + desc = "undefined instruction"; + break; + case SIGSEGV: + desc = "illegal memory access"; + break; + default: + desc = "unknown or unrecoverable error"; + break; + } + + /* Force signals we don't understand to SIGKILL */ + if (WARN_ON(signal != SIGKILL && + siginfo_layout(signal, code) != SIL_FAULT)) { + signal = SIGKILL; + } + + arm64_notify_die(desc, regs, signal, code, (void __user *)address, err); +} + +/* + * Set up process info to signal segmentation fault - called on access error. + */ +void arm64_notify_segfault(unsigned long addr) +{ + int code; + + mmap_read_lock(current->mm); + if (find_vma(current->mm, addr) == NULL) + code = SEGV_MAPERR; + else + code = SEGV_ACCERR; + mmap_read_unlock(current->mm); + + force_signal_inject(SIGSEGV, code, addr, 0); +} + +void do_el0_undef(struct pt_regs *regs, unsigned long esr) +{ + u32 insn; + + /* check for AArch32 breakpoint instructions */ + if (!aarch32_break_handler(regs)) + return; + + if (user_insn_read(regs, &insn)) + goto out_err; + + if (try_emulate_mrs(regs, insn)) + return; + + if (try_emulate_armv8_deprecated(regs, insn)) + return; + +out_err: + force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0); +} + +void do_el1_undef(struct pt_regs *regs, unsigned long esr) +{ + u32 insn; + + if (aarch64_insn_read((void *)regs->pc, &insn)) + goto out_err; + + if (try_emulate_el1_ssbs(regs, insn)) + return; + +out_err: + die("Oops - Undefined instruction", regs, esr); +} + +void do_el0_bti(struct pt_regs *regs) +{ + force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0); +} + +void do_el1_bti(struct pt_regs *regs, unsigned long esr) +{ + die("Oops - BTI", regs, esr); +} + +void do_el0_fpac(struct pt_regs *regs, unsigned long esr) +{ + force_signal_inject(SIGILL, ILL_ILLOPN, regs->pc, esr); +} + +void do_el1_fpac(struct pt_regs *regs, unsigned long esr) +{ + /* + * Unexpected FPAC exception in the kernel: kill the task before it + * does any more harm. + */ + die("Oops - FPAC", regs, esr); +} + +#define __user_cache_maint(insn, address, res) \ + if (address >= user_addr_max()) { \ + res = -EFAULT; \ + } else { \ + uaccess_ttbr0_enable(); \ + asm volatile ( \ + "1: " insn ", %1\n" \ + " mov %w0, #0\n" \ + "2:\n" \ + " .pushsection .fixup,\"ax\"\n" \ + " .align 2\n" \ + "3: mov %w0, %w2\n" \ + " b 2b\n" \ + " .popsection\n" \ + _ASM_EXTABLE(1b, 3b) \ + : "=r" (res) \ + : "r" (address), "i" (-EFAULT)); \ + uaccess_ttbr0_disable(); \ + } + +static void user_cache_maint_handler(unsigned int esr, struct pt_regs *regs) +{ + unsigned long address; + int rt = ESR_ELx_SYS64_ISS_RT(esr); + int crm = (esr & ESR_ELx_SYS64_ISS_CRM_MASK) >> ESR_ELx_SYS64_ISS_CRM_SHIFT; + int ret = 0; + + address = untagged_addr(pt_regs_read_reg(regs, rt)); + + switch (crm) { + case ESR_ELx_SYS64_ISS_CRM_DC_CVAU: /* DC CVAU, gets promoted */ + __user_cache_maint("dc civac", address, ret); + break; + case ESR_ELx_SYS64_ISS_CRM_DC_CVAC: /* DC CVAC, gets promoted */ + __user_cache_maint("dc civac", address, ret); + break; + case ESR_ELx_SYS64_ISS_CRM_DC_CVADP: /* DC CVADP */ + __user_cache_maint("sys 3, c7, c13, 1", address, ret); + break; + case ESR_ELx_SYS64_ISS_CRM_DC_CVAP: /* DC CVAP */ + __user_cache_maint("sys 3, c7, c12, 1", address, ret); + break; + case ESR_ELx_SYS64_ISS_CRM_DC_CIVAC: /* DC CIVAC */ + __user_cache_maint("dc civac", address, ret); + break; + case ESR_ELx_SYS64_ISS_CRM_IC_IVAU: /* IC IVAU */ + __user_cache_maint("ic ivau", address, ret); + break; + default: + force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0); + return; + } + + if (ret) + arm64_notify_segfault(address); + else + arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); +} + +static void ctr_read_handler(unsigned int esr, struct pt_regs *regs) +{ + int rt = ESR_ELx_SYS64_ISS_RT(esr); + unsigned long val = arm64_ftr_reg_user_value(&arm64_ftr_reg_ctrel0); + + if (cpus_have_const_cap(ARM64_WORKAROUND_1542419)) { + /* Hide DIC so that we can trap the unnecessary maintenance...*/ + val &= ~BIT(CTR_DIC_SHIFT); + + /* ... and fake IminLine to reduce the number of traps. */ + val &= ~CTR_IMINLINE_MASK; + val |= (PAGE_SHIFT - 2) & CTR_IMINLINE_MASK; + } + + pt_regs_write_reg(regs, rt, val); + + arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); +} + +static void cntvct_read_handler(unsigned int esr, struct pt_regs *regs) +{ + int rt = ESR_ELx_SYS64_ISS_RT(esr); + + pt_regs_write_reg(regs, rt, arch_timer_read_counter()); + arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); +} + +static void cntfrq_read_handler(unsigned int esr, struct pt_regs *regs) +{ + int rt = ESR_ELx_SYS64_ISS_RT(esr); + + pt_regs_write_reg(regs, rt, arch_timer_get_rate()); + arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); +} + +static void mrs_handler(unsigned int esr, struct pt_regs *regs) +{ + u32 sysreg, rt; + + rt = ESR_ELx_SYS64_ISS_RT(esr); + sysreg = esr_sys64_to_sysreg(esr); + + if (do_emulate_mrs(regs, sysreg, rt) != 0) + force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0); +} + +static void wfi_handler(unsigned int esr, struct pt_regs *regs) +{ + arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); +} + +struct sys64_hook { + unsigned int esr_mask; + unsigned int esr_val; + void (*handler)(unsigned int esr, struct pt_regs *regs); +}; + +static const struct sys64_hook sys64_hooks[] = { + { + .esr_mask = ESR_ELx_SYS64_ISS_EL0_CACHE_OP_MASK, + .esr_val = ESR_ELx_SYS64_ISS_EL0_CACHE_OP_VAL, + .handler = user_cache_maint_handler, + }, + { + /* Trap read access to CTR_EL0 */ + .esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK, + .esr_val = ESR_ELx_SYS64_ISS_SYS_CTR_READ, + .handler = ctr_read_handler, + }, + { + /* Trap read access to CNTVCT_EL0 */ + .esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK, + .esr_val = ESR_ELx_SYS64_ISS_SYS_CNTVCT, + .handler = cntvct_read_handler, + }, + { + /* Trap read access to CNTFRQ_EL0 */ + .esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK, + .esr_val = ESR_ELx_SYS64_ISS_SYS_CNTFRQ, + .handler = cntfrq_read_handler, + }, + { + /* Trap read access to CPUID registers */ + .esr_mask = ESR_ELx_SYS64_ISS_SYS_MRS_OP_MASK, + .esr_val = ESR_ELx_SYS64_ISS_SYS_MRS_OP_VAL, + .handler = mrs_handler, + }, + { + /* Trap WFI instructions executed in userspace */ + .esr_mask = ESR_ELx_WFx_MASK, + .esr_val = ESR_ELx_WFx_WFI_VAL, + .handler = wfi_handler, + }, + {}, +}; + +#ifdef CONFIG_COMPAT +static bool cp15_cond_valid(unsigned int esr, struct pt_regs *regs) +{ + int cond; + + /* Only a T32 instruction can trap without CV being set */ + if (!(esr & ESR_ELx_CV)) { + u32 it; + + it = compat_get_it_state(regs); + if (!it) + return true; + + cond = it >> 4; + } else { + cond = (esr & ESR_ELx_COND_MASK) >> ESR_ELx_COND_SHIFT; + } + + return aarch32_opcode_cond_checks[cond](regs->pstate); +} + +static void compat_cntfrq_read_handler(unsigned int esr, struct pt_regs *regs) +{ + int reg = (esr & ESR_ELx_CP15_32_ISS_RT_MASK) >> ESR_ELx_CP15_32_ISS_RT_SHIFT; + + pt_regs_write_reg(regs, reg, arch_timer_get_rate()); + arm64_skip_faulting_instruction(regs, 4); +} + +static const struct sys64_hook cp15_32_hooks[] = { + { + .esr_mask = ESR_ELx_CP15_32_ISS_SYS_MASK, + .esr_val = ESR_ELx_CP15_32_ISS_SYS_CNTFRQ, + .handler = compat_cntfrq_read_handler, + }, + {}, +}; + +static void compat_cntvct_read_handler(unsigned int esr, struct pt_regs *regs) +{ + int rt = (esr & ESR_ELx_CP15_64_ISS_RT_MASK) >> ESR_ELx_CP15_64_ISS_RT_SHIFT; + int rt2 = (esr & ESR_ELx_CP15_64_ISS_RT2_MASK) >> ESR_ELx_CP15_64_ISS_RT2_SHIFT; + u64 val = arch_timer_read_counter(); + + pt_regs_write_reg(regs, rt, lower_32_bits(val)); + pt_regs_write_reg(regs, rt2, upper_32_bits(val)); + arm64_skip_faulting_instruction(regs, 4); +} + +static const struct sys64_hook cp15_64_hooks[] = { + { + .esr_mask = ESR_ELx_CP15_64_ISS_SYS_MASK, + .esr_val = ESR_ELx_CP15_64_ISS_SYS_CNTVCT, + .handler = compat_cntvct_read_handler, + }, + {}, +}; + +void do_el0_cp15(unsigned long esr, struct pt_regs *regs) +{ + const struct sys64_hook *hook, *hook_base; + + if (!cp15_cond_valid(esr, regs)) { + /* + * There is no T16 variant of a CP access, so we + * always advance PC by 4 bytes. + */ + arm64_skip_faulting_instruction(regs, 4); + return; + } + + switch (ESR_ELx_EC(esr)) { + case ESR_ELx_EC_CP15_32: + hook_base = cp15_32_hooks; + break; + case ESR_ELx_EC_CP15_64: + hook_base = cp15_64_hooks; + break; + default: + do_el0_undef(regs, esr); + return; + } + + for (hook = hook_base; hook->handler; hook++) + if ((hook->esr_mask & esr) == hook->esr_val) { + hook->handler(esr, regs); + return; + } + + /* + * New cp15 instructions may previously have been undefined at + * EL0. Fall back to our usual undefined instruction handler + * so that we handle these consistently. + */ + do_el0_undef(regs, esr); +} +#endif + +void do_el0_sys(unsigned long esr, struct pt_regs *regs) +{ + const struct sys64_hook *hook; + + for (hook = sys64_hooks; hook->handler; hook++) + if ((hook->esr_mask & esr) == hook->esr_val) { + hook->handler(esr, regs); + return; + } + + /* + * New SYS instructions may previously have been undefined at EL0. Fall + * back to our usual undefined instruction handler so that we handle + * these consistently. + */ + do_el0_undef(regs, esr); +} + +static const char *esr_class_str[] = { + [0 ... ESR_ELx_EC_MAX] = "UNRECOGNIZED EC", + [ESR_ELx_EC_UNKNOWN] = "Unknown/Uncategorized", + [ESR_ELx_EC_WFx] = "WFI/WFE", + [ESR_ELx_EC_CP15_32] = "CP15 MCR/MRC", + [ESR_ELx_EC_CP15_64] = "CP15 MCRR/MRRC", + [ESR_ELx_EC_CP14_MR] = "CP14 MCR/MRC", + [ESR_ELx_EC_CP14_LS] = "CP14 LDC/STC", + [ESR_ELx_EC_FP_ASIMD] = "ASIMD", + [ESR_ELx_EC_CP10_ID] = "CP10 MRC/VMRS", + [ESR_ELx_EC_PAC] = "PAC", + [ESR_ELx_EC_CP14_64] = "CP14 MCRR/MRRC", + [ESR_ELx_EC_BTI] = "BTI", + [ESR_ELx_EC_ILL] = "PSTATE.IL", + [ESR_ELx_EC_SVC32] = "SVC (AArch32)", + [ESR_ELx_EC_HVC32] = "HVC (AArch32)", + [ESR_ELx_EC_SMC32] = "SMC (AArch32)", + [ESR_ELx_EC_SVC64] = "SVC (AArch64)", + [ESR_ELx_EC_HVC64] = "HVC (AArch64)", + [ESR_ELx_EC_SMC64] = "SMC (AArch64)", + [ESR_ELx_EC_SYS64] = "MSR/MRS (AArch64)", + [ESR_ELx_EC_SVE] = "SVE", + [ESR_ELx_EC_ERET] = "ERET/ERETAA/ERETAB", + [ESR_ELx_EC_FPAC] = "FPAC", + [ESR_ELx_EC_IMP_DEF] = "EL3 IMP DEF", + [ESR_ELx_EC_IABT_LOW] = "IABT (lower EL)", + [ESR_ELx_EC_IABT_CUR] = "IABT (current EL)", + [ESR_ELx_EC_PC_ALIGN] = "PC Alignment", + [ESR_ELx_EC_DABT_LOW] = "DABT (lower EL)", + [ESR_ELx_EC_DABT_CUR] = "DABT (current EL)", + [ESR_ELx_EC_SP_ALIGN] = "SP Alignment", + [ESR_ELx_EC_FP_EXC32] = "FP (AArch32)", + [ESR_ELx_EC_FP_EXC64] = "FP (AArch64)", + [ESR_ELx_EC_SERROR] = "SError", + [ESR_ELx_EC_BREAKPT_LOW] = "Breakpoint (lower EL)", + [ESR_ELx_EC_BREAKPT_CUR] = "Breakpoint (current EL)", + [ESR_ELx_EC_SOFTSTP_LOW] = "Software Step (lower EL)", + [ESR_ELx_EC_SOFTSTP_CUR] = "Software Step (current EL)", + [ESR_ELx_EC_WATCHPT_LOW] = "Watchpoint (lower EL)", + [ESR_ELx_EC_WATCHPT_CUR] = "Watchpoint (current EL)", + [ESR_ELx_EC_BKPT32] = "BKPT (AArch32)", + [ESR_ELx_EC_VECTOR32] = "Vector catch (AArch32)", + [ESR_ELx_EC_BRK64] = "BRK (AArch64)", +}; + +const char *esr_get_class_string(u32 esr) +{ + return esr_class_str[ESR_ELx_EC(esr)]; +} + +/* + * bad_mode handles the impossible case in the exception vector. This is always + * fatal. + */ +asmlinkage void notrace bad_mode(struct pt_regs *regs, int reason, unsigned int esr) +{ + arm64_enter_nmi(regs); + + console_verbose(); + + pr_crit("Bad mode in %s handler detected on CPU%d, code 0x%08x -- %s\n", + handler[reason], smp_processor_id(), esr, + esr_get_class_string(esr)); + + __show_regs(regs); + local_daif_mask(); + panic("bad mode"); +} + +/* + * bad_el0_sync handles unexpected, but potentially recoverable synchronous + * exceptions taken from EL0. Unlike bad_mode, this returns. + */ +void bad_el0_sync(struct pt_regs *regs, int reason, unsigned int esr) +{ + void __user *pc = (void __user *)instruction_pointer(regs); + + current->thread.fault_address = 0; + current->thread.fault_code = esr; + + arm64_force_sig_fault(SIGILL, ILL_ILLOPC, pc, + "Bad EL0 synchronous exception"); +} + +#ifdef CONFIG_VMAP_STACK + +DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack) + __aligned(16); + +asmlinkage void noinstr handle_bad_stack(struct pt_regs *regs) +{ + unsigned long tsk_stk = (unsigned long)current->stack; + unsigned long irq_stk = (unsigned long)this_cpu_read(irq_stack_ptr); + unsigned long ovf_stk = (unsigned long)this_cpu_ptr(overflow_stack); + unsigned int esr = read_sysreg(esr_el1); + unsigned long far = read_sysreg(far_el1); + + arm64_enter_nmi(regs); + + console_verbose(); + pr_emerg("Insufficient stack space to handle exception!"); + + pr_emerg("ESR: 0x%08x -- %s\n", esr, esr_get_class_string(esr)); + pr_emerg("FAR: 0x%016lx\n", far); + + pr_emerg("Task stack: [0x%016lx..0x%016lx]\n", + tsk_stk, tsk_stk + THREAD_SIZE); + pr_emerg("IRQ stack: [0x%016lx..0x%016lx]\n", + irq_stk, irq_stk + IRQ_STACK_SIZE); + pr_emerg("Overflow stack: [0x%016lx..0x%016lx]\n", + ovf_stk, ovf_stk + OVERFLOW_STACK_SIZE); + + __show_regs(regs); + + /* + * We use nmi_panic to limit the potential for recusive overflows, and + * to get a better stack trace. + */ + nmi_panic(NULL, "kernel stack overflow"); + cpu_park_loop(); +} +#endif + +void __noreturn arm64_serror_panic(struct pt_regs *regs, u32 esr) +{ + console_verbose(); + + pr_crit("SError Interrupt on CPU%d, code 0x%08x -- %s\n", + smp_processor_id(), esr, esr_get_class_string(esr)); + if (regs) + __show_regs(regs); + + nmi_panic(regs, "Asynchronous SError Interrupt"); + + cpu_park_loop(); + unreachable(); +} + +bool arm64_is_fatal_ras_serror(struct pt_regs *regs, unsigned int esr) +{ + u32 aet = arm64_ras_serror_get_severity(esr); + + switch (aet) { + case ESR_ELx_AET_CE: /* corrected error */ + case ESR_ELx_AET_UEO: /* restartable, not yet consumed */ + /* + * The CPU can make progress. We may take UEO again as + * a more severe error. + */ + return false; + + case ESR_ELx_AET_UEU: /* Uncorrected Unrecoverable */ + case ESR_ELx_AET_UER: /* Uncorrected Recoverable */ + /* + * The CPU can't make progress. The exception may have + * been imprecise. + * + * Neoverse-N1 #1349291 means a non-KVM SError reported as + * Unrecoverable should be treated as Uncontainable. We + * call arm64_serror_panic() in both cases. + */ + return true; + + case ESR_ELx_AET_UC: /* Uncontainable or Uncategorized error */ + default: + /* Error has been silently propagated */ + arm64_serror_panic(regs, esr); + } +} + +asmlinkage void noinstr do_serror(struct pt_regs *regs, unsigned int esr) +{ + arm64_enter_nmi(regs); + + /* non-RAS errors are not containable */ + if (!arm64_is_ras_serror(esr) || arm64_is_fatal_ras_serror(regs, esr)) + arm64_serror_panic(regs, esr); + + arm64_exit_nmi(regs); +} + +/* GENERIC_BUG traps */ + +int is_valid_bugaddr(unsigned long addr) +{ + /* + * bug_handler() only called for BRK #BUG_BRK_IMM. + * So the answer is trivial -- any spurious instances with no + * bug table entry will be rejected by report_bug() and passed + * back to the debug-monitors code and handled as a fatal + * unexpected debug exception. + */ + return 1; +} + +static int bug_handler(struct pt_regs *regs, unsigned int esr) +{ + switch (report_bug(regs->pc, regs)) { + case BUG_TRAP_TYPE_BUG: + die("Oops - BUG", regs, esr); + break; + + case BUG_TRAP_TYPE_WARN: + break; + + default: + /* unknown/unrecognised bug trap type */ + return DBG_HOOK_ERROR; + } + + /* If thread survives, skip over the BUG instruction and continue: */ + arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); + return DBG_HOOK_HANDLED; +} + +static struct break_hook bug_break_hook = { + .fn = bug_handler, + .imm = BUG_BRK_IMM, +}; + +static int reserved_fault_handler(struct pt_regs *regs, unsigned int esr) +{ + pr_err("%s generated an invalid instruction at %pS!\n", + in_bpf_jit(regs) ? "BPF JIT" : "Kernel text patching", + (void *)instruction_pointer(regs)); + + /* We cannot handle this */ + return DBG_HOOK_ERROR; +} + +static struct break_hook fault_break_hook = { + .fn = reserved_fault_handler, + .imm = FAULT_BRK_IMM, +}; + +#ifdef CONFIG_KASAN_SW_TAGS + +#define KASAN_ESR_RECOVER 0x20 +#define KASAN_ESR_WRITE 0x10 +#define KASAN_ESR_SIZE_MASK 0x0f +#define KASAN_ESR_SIZE(esr) (1 << ((esr) & KASAN_ESR_SIZE_MASK)) + +static int kasan_handler(struct pt_regs *regs, unsigned int esr) +{ + bool recover = esr & KASAN_ESR_RECOVER; + bool write = esr & KASAN_ESR_WRITE; + size_t size = KASAN_ESR_SIZE(esr); + u64 addr = regs->regs[0]; + u64 pc = regs->pc; + + kasan_report(addr, size, write, pc); + + /* + * The instrumentation allows to control whether we can proceed after + * a crash was detected. This is done by passing the -recover flag to + * the compiler. Disabling recovery allows to generate more compact + * code. + * + * Unfortunately disabling recovery doesn't work for the kernel right + * now. KASAN reporting is disabled in some contexts (for example when + * the allocator accesses slab object metadata; this is controlled by + * current->kasan_depth). All these accesses are detected by the tool, + * even though the reports for them are not printed. + * + * This is something that might be fixed at some point in the future. + */ + if (!recover) + die("Oops - KASAN", regs, esr); + + /* If thread survives, skip over the brk instruction and continue: */ + arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); + return DBG_HOOK_HANDLED; +} + +static struct break_hook kasan_break_hook = { + .fn = kasan_handler, + .imm = KASAN_BRK_IMM, + .mask = KASAN_BRK_MASK, +}; +#endif + +/* + * Initial handler for AArch64 BRK exceptions + * This handler only used until debug_traps_init(). + */ +int __init early_brk64(unsigned long addr, unsigned int esr, + struct pt_regs *regs) +{ +#ifdef CONFIG_KASAN_SW_TAGS + unsigned int comment = esr & ESR_ELx_BRK64_ISS_COMMENT_MASK; + + if ((comment & ~KASAN_BRK_MASK) == KASAN_BRK_IMM) + return kasan_handler(regs, esr) != DBG_HOOK_HANDLED; +#endif + return bug_handler(regs, esr) != DBG_HOOK_HANDLED; +} + +void __init trap_init(void) +{ + register_kernel_break_hook(&bug_break_hook); + register_kernel_break_hook(&fault_break_hook); +#ifdef CONFIG_KASAN_SW_TAGS + register_kernel_break_hook(&kasan_break_hook); +#endif + debug_traps_init(); +} |