diff options
Diffstat (limited to 'arch/riscv/kernel/traps.c')
| -rw-r--r-- | arch/riscv/kernel/traps.c | 343 |
1 files changed, 307 insertions, 36 deletions
diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c index f4cad5163bf2..868d6280cf66 100644 --- a/arch/riscv/kernel/traps.c +++ b/arch/riscv/kernel/traps.c @@ -6,46 +6,101 @@ #include <linux/cpu.h> #include <linux/kernel.h> #include <linux/init.h> +#include <linux/randomize_kstack.h> #include <linux/sched.h> #include <linux/sched/debug.h> #include <linux/sched/signal.h> #include <linux/signal.h> #include <linux/kdebug.h> #include <linux/uaccess.h> +#include <linux/kprobes.h> +#include <linux/uprobes.h> +#include <asm/uprobes.h> #include <linux/mm.h> #include <linux/module.h> #include <linux/irq.h> +#include <linux/kexec.h> +#include <linux/entry-common.h> +#include <asm/asm-prototypes.h> +#include <asm/bug.h> +#include <asm/cfi.h> +#include <asm/csr.h> #include <asm/processor.h> #include <asm/ptrace.h> -#include <asm/csr.h> +#include <asm/syscall.h> +#include <asm/thread_info.h> +#include <asm/vector.h> +#include <asm/irq_stack.h> int show_unhandled_signals = 1; -extern asmlinkage void handle_exception(void); - static DEFINE_SPINLOCK(die_lock); +static int copy_code(struct pt_regs *regs, u16 *val, const u16 *insns) +{ + const void __user *uaddr = (__force const void __user *)insns; + + if (!user_mode(regs)) + return get_kernel_nofault(*val, insns); + + /* The user space code from other tasks cannot be accessed. */ + if (regs != task_pt_regs(current)) + return -EPERM; + + return copy_from_user_nofault(val, uaddr, sizeof(*val)); +} + +static void dump_instr(const char *loglvl, struct pt_regs *regs) +{ + char str[sizeof("0000 ") * 12 + 2 + 1], *p = str; + const u16 *insns = (u16 *)instruction_pointer(regs); + long bad; + u16 val; + int i; + + for (i = -10; i < 2; i++) { + bad = copy_code(regs, &val, &insns[i]); + if (!bad) { + p += sprintf(p, i == 0 ? "(%04hx) " : "%04hx ", val); + } else { + printk("%sCode: Unable to access instruction at 0x%px.\n", + loglvl, &insns[i]); + return; + } + } + printk("%sCode: %s\n", loglvl, str); +} + void die(struct pt_regs *regs, const char *str) { static int die_counter; int ret; + long cause; + unsigned long flags; oops_enter(); - spin_lock_irq(&die_lock); + spin_lock_irqsave(&die_lock, flags); console_verbose(); bust_spinlocks(1); pr_emerg("%s [#%d]\n", str, ++die_counter); print_modules(); - show_regs(regs); + if (regs) { + show_regs(regs); + dump_instr(KERN_EMERG, regs); + } + + cause = regs ? regs->cause : -1; + ret = notify_die(DIE_OOPS, str, regs, 0, cause, SIGSEGV); - ret = notify_die(DIE_OOPS, str, regs, 0, regs->cause, SIGSEGV); + if (kexec_should_crash(current)) + crash_kexec(regs); bust_spinlocks(0); add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); - spin_unlock_irq(&die_lock); + spin_unlock_irqrestore(&die_lock, flags); oops_exit(); if (in_interrupt()) @@ -53,7 +108,7 @@ void die(struct pt_regs *regs, const char *str) if (panic_on_oops) panic("Fatal exception"); if (ret != NOTIFY_STOP) - do_exit(SIGSEGV); + make_task_dead(SIGSEGV); } void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr) @@ -66,7 +121,8 @@ void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr) tsk->comm, task_pid_nr(tsk), signo, code, addr); print_vma_addr(KERN_CONT " in ", instruction_pointer(regs)); pr_cont("\n"); - show_regs(regs); + __show_regs(regs); + dump_instr(KERN_EMERG, regs); } force_sig_fault(signo, code, (void __user *)addr); @@ -75,6 +131,8 @@ void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr) static void do_trap_error(struct pt_regs *regs, int signo, int code, unsigned long addr, const char *str) { + current->thread.bad_cause = regs->cause; + if (user_mode(regs)) { do_trap(regs, signo, code, addr); } else { @@ -83,10 +141,23 @@ static void do_trap_error(struct pt_regs *regs, int signo, int code, } } -#define DO_ERROR_INFO(name, signo, code, str) \ -asmlinkage __visible void name(struct pt_regs *regs) \ -{ \ - do_trap_error(regs, signo, code, regs->epc, "Oops - " str); \ +#if defined(CONFIG_XIP_KERNEL) && defined(CONFIG_RISCV_ALTERNATIVE) +#define __trap_section __noinstr_section(".xip.traps") +#else +#define __trap_section noinstr +#endif +#define DO_ERROR_INFO(name, signo, code, str) \ +asmlinkage __visible __trap_section void name(struct pt_regs *regs) \ +{ \ + if (user_mode(regs)) { \ + irqentry_enter_from_user_mode(regs); \ + do_trap_error(regs, signo, code, regs->epc, "Oops - " str); \ + irqentry_exit_to_user_mode(regs); \ + } else { \ + irqentry_state_t state = irqentry_nmi_enter(regs); \ + do_trap_error(regs, signo, code, regs->epc, "Oops - " str); \ + irqentry_nmi_exit(regs, state); \ + } \ } DO_ERROR_INFO(do_trap_unknown, @@ -95,18 +166,81 @@ DO_ERROR_INFO(do_trap_insn_misaligned, SIGBUS, BUS_ADRALN, "instruction address misaligned"); DO_ERROR_INFO(do_trap_insn_fault, SIGSEGV, SEGV_ACCERR, "instruction access fault"); -DO_ERROR_INFO(do_trap_insn_illegal, - SIGILL, ILL_ILLOPC, "illegal instruction"); -DO_ERROR_INFO(do_trap_load_misaligned, - SIGBUS, BUS_ADRALN, "load address misaligned"); + +asmlinkage __visible __trap_section void do_trap_insn_illegal(struct pt_regs *regs) +{ + bool handled; + + if (user_mode(regs)) { + irqentry_enter_from_user_mode(regs); + + local_irq_enable(); + + handled = riscv_v_first_use_handler(regs); + + local_irq_disable(); + + if (!handled) + do_trap_error(regs, SIGILL, ILL_ILLOPC, regs->epc, + "Oops - illegal instruction"); + + irqentry_exit_to_user_mode(regs); + } else { + irqentry_state_t state = irqentry_nmi_enter(regs); + + do_trap_error(regs, SIGILL, ILL_ILLOPC, regs->epc, + "Oops - illegal instruction"); + + irqentry_nmi_exit(regs, state); + } +} + DO_ERROR_INFO(do_trap_load_fault, SIGSEGV, SEGV_ACCERR, "load access fault"); -DO_ERROR_INFO(do_trap_store_misaligned, - SIGBUS, BUS_ADRALN, "store (or AMO) address misaligned"); + +asmlinkage __visible __trap_section void do_trap_load_misaligned(struct pt_regs *regs) +{ + if (user_mode(regs)) { + irqentry_enter_from_user_mode(regs); + + if (handle_misaligned_load(regs)) + do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc, + "Oops - load address misaligned"); + + irqentry_exit_to_user_mode(regs); + } else { + irqentry_state_t state = irqentry_nmi_enter(regs); + + if (handle_misaligned_load(regs)) + do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc, + "Oops - load address misaligned"); + + irqentry_nmi_exit(regs, state); + } +} + +asmlinkage __visible __trap_section void do_trap_store_misaligned(struct pt_regs *regs) +{ + if (user_mode(regs)) { + irqentry_enter_from_user_mode(regs); + + if (handle_misaligned_store(regs)) + do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc, + "Oops - store (or AMO) address misaligned"); + + irqentry_exit_to_user_mode(regs); + } else { + irqentry_state_t state = irqentry_nmi_enter(regs); + + if (handle_misaligned_store(regs)) + do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc, + "Oops - store (or AMO) address misaligned"); + + irqentry_nmi_exit(regs, state); + } +} DO_ERROR_INFO(do_trap_store_fault, SIGSEGV, SEGV_ACCERR, "store (or AMO) access fault"); -DO_ERROR_INFO(do_trap_ecall_u, - SIGILL, ILL_ILLTRP, "environment call from U-mode"); DO_ERROR_INFO(do_trap_ecall_s, SIGILL, ILL_ILLTRP, "environment call from S-mode"); DO_ERROR_INFO(do_trap_ecall_m, @@ -116,21 +250,146 @@ static inline unsigned long get_break_insn_length(unsigned long pc) { bug_insn_t insn; - if (probe_kernel_address((bug_insn_t *)pc, insn)) + if (get_kernel_nofault(insn, (bug_insn_t *)pc)) return 0; - return (((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32) ? 4UL : 2UL); + + return GET_INSN_LENGTH(insn); } -asmlinkage __visible void do_trap_break(struct pt_regs *regs) +static bool probe_single_step_handler(struct pt_regs *regs) { + bool user = user_mode(regs); + + return user ? uprobe_single_step_handler(regs) : kprobe_single_step_handler(regs); +} + +static bool probe_breakpoint_handler(struct pt_regs *regs) +{ + bool user = user_mode(regs); + + return user ? uprobe_breakpoint_handler(regs) : kprobe_breakpoint_handler(regs); +} + +void handle_break(struct pt_regs *regs) +{ + if (probe_single_step_handler(regs)) + return; + + if (probe_breakpoint_handler(regs)) + return; + + current->thread.bad_cause = regs->cause; + if (user_mode(regs)) force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->epc); - else if (report_bug(regs->epc, regs) == BUG_TRAP_TYPE_WARN) +#ifdef CONFIG_KGDB + else if (notify_die(DIE_TRAP, "EBREAK", regs, 0, regs->cause, SIGTRAP) + == NOTIFY_STOP) + return; +#endif + else if (report_bug(regs->epc, regs) == BUG_TRAP_TYPE_WARN || + handle_cfi_failure(regs) == BUG_TRAP_TYPE_WARN) regs->epc += get_break_insn_length(regs->epc); else die(regs, "Kernel BUG"); } +asmlinkage __visible __trap_section void do_trap_break(struct pt_regs *regs) +{ + if (user_mode(regs)) { + irqentry_enter_from_user_mode(regs); + + handle_break(regs); + + irqentry_exit_to_user_mode(regs); + } else { + irqentry_state_t state = irqentry_nmi_enter(regs); + + handle_break(regs); + + irqentry_nmi_exit(regs, state); + } +} + +asmlinkage __visible __trap_section __no_stack_protector +void do_trap_ecall_u(struct pt_regs *regs) +{ + if (user_mode(regs)) { + long syscall = regs->a7; + + regs->epc += 4; + regs->orig_a0 = regs->a0; + + riscv_v_vstate_discard(regs); + + syscall = syscall_enter_from_user_mode(regs, syscall); + + add_random_kstack_offset(); + + if (syscall >= 0 && syscall < NR_syscalls) + syscall_handler(regs, syscall); + else if (syscall != -1) + regs->a0 = -ENOSYS; + /* + * Ultimately, this value will get limited by KSTACK_OFFSET_MAX(), + * so the maximum stack offset is 1k bytes (10 bits). + * + * The actual entropy will be further reduced by the compiler when + * applying stack alignment constraints: 16-byte (i.e. 4-bit) aligned + * for RV32I or RV64I. + * + * The resulting 6 bits of entropy is seen in SP[9:4]. + */ + choose_random_kstack_offset(get_random_u16()); + + syscall_exit_to_user_mode(regs); + } else { + irqentry_state_t state = irqentry_nmi_enter(regs); + + do_trap_error(regs, SIGILL, ILL_ILLTRP, regs->epc, + "Oops - environment call from U-mode"); + + irqentry_nmi_exit(regs, state); + } + +} + +#ifdef CONFIG_MMU +asmlinkage __visible noinstr void do_page_fault(struct pt_regs *regs) +{ + irqentry_state_t state = irqentry_enter(regs); + + handle_page_fault(regs); + + local_irq_disable(); + + irqentry_exit(regs, state); +} +#endif + +static void noinstr handle_riscv_irq(struct pt_regs *regs) +{ + struct pt_regs *old_regs; + + irq_enter_rcu(); + old_regs = set_irq_regs(regs); + handle_arch_irq(regs); + set_irq_regs(old_regs); + irq_exit_rcu(); +} + +asmlinkage void noinstr do_irq(struct pt_regs *regs) +{ + irqentry_state_t state = irqentry_enter(regs); + + if (IS_ENABLED(CONFIG_IRQ_STACKS) && on_thread_stack()) + call_on_irq_stack(regs, handle_riscv_irq); + else + handle_riscv_irq(regs); + + irqentry_exit(regs, state); +} + #ifdef CONFIG_GENERIC_BUG int is_valid_bugaddr(unsigned long pc) { @@ -138,7 +397,7 @@ int is_valid_bugaddr(unsigned long pc) if (pc < VMALLOC_START) return 0; - if (probe_kernel_address((bug_insn_t *)pc, insn)) + if (get_kernel_nofault(insn, (bug_insn_t *)pc)) return 0; if ((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32) return (insn == __BUG_INSN_32); @@ -147,15 +406,27 @@ int is_valid_bugaddr(unsigned long pc) } #endif /* CONFIG_GENERIC_BUG */ -void __init trap_init(void) +#ifdef CONFIG_VMAP_STACK +DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], + overflow_stack)__aligned(16); + +asmlinkage void handle_bad_stack(struct pt_regs *regs) { - /* - * Set sup0 scratch register to 0, indicating to exception vector - * that we are presently executing in the kernel - */ - csr_write(CSR_SCRATCH, 0); - /* Set the exception vector address */ - csr_write(CSR_TVEC, &handle_exception); - /* Enable all interrupts */ - csr_write(CSR_IE, -1); + unsigned long tsk_stk = (unsigned long)current->stack; + unsigned long ovf_stk = (unsigned long)this_cpu_ptr(overflow_stack); + + console_verbose(); + + pr_emerg("Insufficient stack space to handle exception!\n"); + pr_emerg("Task stack: [0x%016lx..0x%016lx]\n", + tsk_stk, tsk_stk + THREAD_SIZE); + pr_emerg("Overflow stack: [0x%016lx..0x%016lx]\n", + ovf_stk, ovf_stk + OVERFLOW_STACK_SIZE); + + __show_regs(regs); + panic("Kernel stack overflow"); + + for (;;) + wait_for_interrupt(); } +#endif |