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- /*
- * arch/xtensa/kernel/traps.c
- *
- * Exception handling.
- *
- * Derived from code with the following copyrights:
- * Copyright (C) 1994 - 1999 by Ralf Baechle
- * Modified for R3000 by Paul M. Antoine, 1995, 1996
- * Complete output from die() by Ulf Carlsson, 1998
- * Copyright (C) 1999 Silicon Graphics, Inc.
- *
- * Essentially rewritten for the Xtensa architecture port.
- *
- * Copyright (C) 2001 - 2013 Tensilica Inc.
- *
- * Joe Taylor <[email protected], [email protected]>
- * Chris Zankel <[email protected]>
- * Marc Gauthier<[email protected], [email protected]>
- * Kevin Chea
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License. See the file "COPYING" in the main directory of this archive
- * for more details.
- */
- #include <linux/kernel.h>
- #include <linux/sched/signal.h>
- #include <linux/sched/debug.h>
- #include <linux/sched/task_stack.h>
- #include <linux/init.h>
- #include <linux/module.h>
- #include <linux/stringify.h>
- #include <linux/kallsyms.h>
- #include <linux/delay.h>
- #include <linux/hardirq.h>
- #include <linux/ratelimit.h>
- #include <linux/pgtable.h>
- #include <asm/stacktrace.h>
- #include <asm/ptrace.h>
- #include <asm/timex.h>
- #include <linux/uaccess.h>
- #include <asm/processor.h>
- #include <asm/traps.h>
- #include <asm/hw_breakpoint.h>
- /*
- * Machine specific interrupt handlers
- */
- static void do_illegal_instruction(struct pt_regs *regs);
- static void do_div0(struct pt_regs *regs);
- static void do_interrupt(struct pt_regs *regs);
- #if XTENSA_FAKE_NMI
- static void do_nmi(struct pt_regs *regs);
- #endif
- #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
- static void do_unaligned_user(struct pt_regs *regs);
- #endif
- static void do_multihit(struct pt_regs *regs);
- #if XTENSA_HAVE_COPROCESSORS
- static void do_coprocessor(struct pt_regs *regs);
- #endif
- static void do_debug(struct pt_regs *regs);
- /*
- * The vector table must be preceded by a save area (which
- * implies it must be in RAM, unless one places RAM immediately
- * before a ROM and puts the vector at the start of the ROM (!))
- */
- #define KRNL 0x01
- #define USER 0x02
- #define COPROCESSOR(x) \
- { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER|KRNL, fast_coprocessor },\
- { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, 0, do_coprocessor }
- typedef struct {
- int cause;
- int fast;
- void* handler;
- } dispatch_init_table_t;
- static dispatch_init_table_t __initdata dispatch_init_table[] = {
- #ifdef CONFIG_USER_ABI_CALL0_PROBE
- { EXCCAUSE_ILLEGAL_INSTRUCTION, USER, fast_illegal_instruction_user },
- #endif
- { EXCCAUSE_ILLEGAL_INSTRUCTION, 0, do_illegal_instruction},
- { EXCCAUSE_SYSTEM_CALL, USER, fast_syscall_user },
- { EXCCAUSE_SYSTEM_CALL, 0, system_call },
- /* EXCCAUSE_INSTRUCTION_FETCH unhandled */
- /* EXCCAUSE_LOAD_STORE_ERROR unhandled*/
- { EXCCAUSE_LEVEL1_INTERRUPT, 0, do_interrupt },
- #ifdef SUPPORT_WINDOWED
- { EXCCAUSE_ALLOCA, USER|KRNL, fast_alloca },
- #endif
- { EXCCAUSE_INTEGER_DIVIDE_BY_ZERO, 0, do_div0 },
- /* EXCCAUSE_PRIVILEGED unhandled */
- #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
- #ifdef CONFIG_XTENSA_UNALIGNED_USER
- { EXCCAUSE_UNALIGNED, USER, fast_unaligned },
- #endif
- { EXCCAUSE_UNALIGNED, 0, do_unaligned_user },
- { EXCCAUSE_UNALIGNED, KRNL, fast_unaligned },
- #endif
- #ifdef CONFIG_MMU
- { EXCCAUSE_ITLB_MISS, 0, do_page_fault },
- { EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss},
- { EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss},
- { EXCCAUSE_DTLB_MISS, 0, do_page_fault },
- { EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited },
- #endif /* CONFIG_MMU */
- #ifdef CONFIG_PFAULT
- { EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit },
- { EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault },
- { EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault },
- { EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit },
- { EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault },
- { EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault },
- { EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault },
- #endif
- /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
- #if XTENSA_HAVE_COPROCESSOR(0)
- COPROCESSOR(0),
- #endif
- #if XTENSA_HAVE_COPROCESSOR(1)
- COPROCESSOR(1),
- #endif
- #if XTENSA_HAVE_COPROCESSOR(2)
- COPROCESSOR(2),
- #endif
- #if XTENSA_HAVE_COPROCESSOR(3)
- COPROCESSOR(3),
- #endif
- #if XTENSA_HAVE_COPROCESSOR(4)
- COPROCESSOR(4),
- #endif
- #if XTENSA_HAVE_COPROCESSOR(5)
- COPROCESSOR(5),
- #endif
- #if XTENSA_HAVE_COPROCESSOR(6)
- COPROCESSOR(6),
- #endif
- #if XTENSA_HAVE_COPROCESSOR(7)
- COPROCESSOR(7),
- #endif
- #if XTENSA_FAKE_NMI
- { EXCCAUSE_MAPPED_NMI, 0, do_nmi },
- #endif
- { EXCCAUSE_MAPPED_DEBUG, 0, do_debug },
- { -1, -1, 0 }
- };
- /* The exception table <exc_table> serves two functions:
- * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
- * 2. it is a temporary memory buffer for the exception handlers.
- */
- DEFINE_PER_CPU(struct exc_table, exc_table);
- DEFINE_PER_CPU(struct debug_table, debug_table);
- void die(const char*, struct pt_regs*, long);
- static inline void
- __die_if_kernel(const char *str, struct pt_regs *regs, long err)
- {
- if (!user_mode(regs))
- die(str, regs, err);
- }
- /*
- * Unhandled Exceptions. Kill user task or panic if in kernel space.
- */
- void do_unhandled(struct pt_regs *regs)
- {
- __die_if_kernel("Caught unhandled exception - should not happen",
- regs, SIGKILL);
- /* If in user mode, send SIGILL signal to current process */
- pr_info_ratelimited("Caught unhandled exception in '%s' "
- "(pid = %d, pc = %#010lx) - should not happen\n"
- "\tEXCCAUSE is %ld\n",
- current->comm, task_pid_nr(current), regs->pc,
- regs->exccause);
- force_sig(SIGILL);
- }
- /*
- * Multi-hit exception. This if fatal!
- */
- static void do_multihit(struct pt_regs *regs)
- {
- die("Caught multihit exception", regs, SIGKILL);
- }
- /*
- * IRQ handler.
- */
- #if XTENSA_FAKE_NMI
- #define IS_POW2(v) (((v) & ((v) - 1)) == 0)
- #if !(PROFILING_INTLEVEL == XCHAL_EXCM_LEVEL && \
- IS_POW2(XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL)))
- #warning "Fake NMI is requested for PMM, but there are other IRQs at or above its level."
- #warning "Fake NMI will be used, but there will be a bugcheck if one of those IRQs fire."
- static inline void check_valid_nmi(void)
- {
- unsigned intread = xtensa_get_sr(interrupt);
- unsigned intenable = xtensa_get_sr(intenable);
- BUG_ON(intread & intenable &
- ~(XTENSA_INTLEVEL_ANDBELOW_MASK(PROFILING_INTLEVEL) ^
- XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL) ^
- BIT(XCHAL_PROFILING_INTERRUPT)));
- }
- #else
- static inline void check_valid_nmi(void)
- {
- }
- #endif
- irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id);
- DEFINE_PER_CPU(unsigned long, nmi_count);
- static void do_nmi(struct pt_regs *regs)
- {
- struct pt_regs *old_regs = set_irq_regs(regs);
- nmi_enter();
- ++*this_cpu_ptr(&nmi_count);
- check_valid_nmi();
- xtensa_pmu_irq_handler(0, NULL);
- nmi_exit();
- set_irq_regs(old_regs);
- }
- #endif
- static void do_interrupt(struct pt_regs *regs)
- {
- static const unsigned int_level_mask[] = {
- 0,
- XCHAL_INTLEVEL1_MASK,
- XCHAL_INTLEVEL2_MASK,
- XCHAL_INTLEVEL3_MASK,
- XCHAL_INTLEVEL4_MASK,
- XCHAL_INTLEVEL5_MASK,
- XCHAL_INTLEVEL6_MASK,
- XCHAL_INTLEVEL7_MASK,
- };
- struct pt_regs *old_regs = set_irq_regs(regs);
- unsigned unhandled = ~0u;
- irq_enter();
- for (;;) {
- unsigned intread = xtensa_get_sr(interrupt);
- unsigned intenable = xtensa_get_sr(intenable);
- unsigned int_at_level = intread & intenable;
- unsigned level;
- for (level = LOCKLEVEL; level > 0; --level) {
- if (int_at_level & int_level_mask[level]) {
- int_at_level &= int_level_mask[level];
- if (int_at_level & unhandled)
- int_at_level &= unhandled;
- else
- unhandled |= int_level_mask[level];
- break;
- }
- }
- if (level == 0)
- break;
- /* clear lowest pending irq in the unhandled mask */
- unhandled ^= (int_at_level & -int_at_level);
- do_IRQ(__ffs(int_at_level), regs);
- }
- irq_exit();
- set_irq_regs(old_regs);
- }
- static bool check_div0(struct pt_regs *regs)
- {
- static const u8 pattern[] = {'D', 'I', 'V', '0'};
- const u8 *p;
- u8 buf[5];
- if (user_mode(regs)) {
- if (copy_from_user(buf, (void __user *)regs->pc + 2, 5))
- return false;
- p = buf;
- } else {
- p = (const u8 *)regs->pc + 2;
- }
- return memcmp(p, pattern, sizeof(pattern)) == 0 ||
- memcmp(p + 1, pattern, sizeof(pattern)) == 0;
- }
- /*
- * Illegal instruction. Fatal if in kernel space.
- */
- static void do_illegal_instruction(struct pt_regs *regs)
- {
- #ifdef CONFIG_USER_ABI_CALL0_PROBE
- /*
- * When call0 application encounters an illegal instruction fast
- * exception handler will attempt to set PS.WOE and retry failing
- * instruction.
- * If we get here we know that that instruction is also illegal
- * with PS.WOE set, so it's not related to the windowed option
- * hence PS.WOE may be cleared.
- */
- if (regs->pc == current_thread_info()->ps_woe_fix_addr)
- regs->ps &= ~PS_WOE_MASK;
- #endif
- if (check_div0(regs)) {
- do_div0(regs);
- return;
- }
- __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
- /* If in user mode, send SIGILL signal to current process. */
- pr_info_ratelimited("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
- current->comm, task_pid_nr(current), regs->pc);
- force_sig(SIGILL);
- }
- static void do_div0(struct pt_regs *regs)
- {
- __die_if_kernel("Unhandled division by 0 in kernel", regs, SIGKILL);
- force_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)regs->pc);
- }
- /*
- * Handle unaligned memory accesses from user space. Kill task.
- *
- * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
- * accesses causes from user space.
- */
- #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
- static void do_unaligned_user(struct pt_regs *regs)
- {
- __die_if_kernel("Unhandled unaligned exception in kernel",
- regs, SIGKILL);
- current->thread.bad_vaddr = regs->excvaddr;
- current->thread.error_code = -3;
- pr_info_ratelimited("Unaligned memory access to %08lx in '%s' "
- "(pid = %d, pc = %#010lx)\n",
- regs->excvaddr, current->comm,
- task_pid_nr(current), regs->pc);
- force_sig_fault(SIGBUS, BUS_ADRALN, (void *) regs->excvaddr);
- }
- #endif
- #if XTENSA_HAVE_COPROCESSORS
- static void do_coprocessor(struct pt_regs *regs)
- {
- coprocessor_flush_release_all(current_thread_info());
- }
- #endif
- /* Handle debug events.
- * When CONFIG_HAVE_HW_BREAKPOINT is on this handler is called with
- * preemption disabled to avoid rescheduling and keep mapping of hardware
- * breakpoint structures to debug registers intact, so that
- * DEBUGCAUSE.DBNUM could be used in case of data breakpoint hit.
- */
- static void do_debug(struct pt_regs *regs)
- {
- #ifdef CONFIG_HAVE_HW_BREAKPOINT
- int ret = check_hw_breakpoint(regs);
- preempt_enable();
- if (ret == 0)
- return;
- #endif
- __die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
- /* If in user mode, send SIGTRAP signal to current process */
- force_sig(SIGTRAP);
- }
- #define set_handler(type, cause, handler) \
- do { \
- unsigned int cpu; \
- \
- for_each_possible_cpu(cpu) \
- per_cpu(exc_table, cpu).type[cause] = (handler);\
- } while (0)
- /* Set exception C handler - for temporary use when probing exceptions */
- xtensa_exception_handler *
- __init trap_set_handler(int cause, xtensa_exception_handler *handler)
- {
- void *previous = per_cpu(exc_table, 0).default_handler[cause];
- set_handler(default_handler, cause, handler);
- return previous;
- }
- static void trap_init_excsave(void)
- {
- xtensa_set_sr(this_cpu_ptr(&exc_table), excsave1);
- }
- static void trap_init_debug(void)
- {
- unsigned long debugsave = (unsigned long)this_cpu_ptr(&debug_table);
- this_cpu_ptr(&debug_table)->debug_exception = debug_exception;
- __asm__ __volatile__("wsr %0, excsave" __stringify(XCHAL_DEBUGLEVEL)
- :: "a"(debugsave));
- }
- /*
- * Initialize dispatch tables.
- *
- * The exception vectors are stored compressed the __init section in the
- * dispatch_init_table. This function initializes the following three tables
- * from that compressed table:
- * - fast user first dispatch table for user exceptions
- * - fast kernel first dispatch table for kernel exceptions
- * - default C-handler C-handler called by the default fast handler.
- *
- * See vectors.S for more details.
- */
- void __init trap_init(void)
- {
- int i;
- /* Setup default vectors. */
- for (i = 0; i < EXCCAUSE_N; i++) {
- set_handler(fast_user_handler, i, user_exception);
- set_handler(fast_kernel_handler, i, kernel_exception);
- set_handler(default_handler, i, do_unhandled);
- }
- /* Setup specific handlers. */
- for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
- int fast = dispatch_init_table[i].fast;
- int cause = dispatch_init_table[i].cause;
- void *handler = dispatch_init_table[i].handler;
- if (fast == 0)
- set_handler(default_handler, cause, handler);
- if ((fast & USER) != 0)
- set_handler(fast_user_handler, cause, handler);
- if ((fast & KRNL) != 0)
- set_handler(fast_kernel_handler, cause, handler);
- }
- /* Initialize EXCSAVE_1 to hold the address of the exception table. */
- trap_init_excsave();
- trap_init_debug();
- }
- #ifdef CONFIG_SMP
- void secondary_trap_init(void)
- {
- trap_init_excsave();
- trap_init_debug();
- }
- #endif
- /*
- * This function dumps the current valid window frame and other base registers.
- */
- void show_regs(struct pt_regs * regs)
- {
- int i;
- show_regs_print_info(KERN_DEFAULT);
- for (i = 0; i < 16; i++) {
- if ((i % 8) == 0)
- pr_info("a%02d:", i);
- pr_cont(" %08lx", regs->areg[i]);
- }
- pr_cont("\n");
- pr_info("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
- regs->pc, regs->ps, regs->depc, regs->excvaddr);
- pr_info("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
- regs->lbeg, regs->lend, regs->lcount, regs->sar);
- if (user_mode(regs))
- pr_cont("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
- regs->windowbase, regs->windowstart, regs->wmask,
- regs->syscall);
- }
- static int show_trace_cb(struct stackframe *frame, void *data)
- {
- const char *loglvl = data;
- if (kernel_text_address(frame->pc))
- printk("%s [<%08lx>] %pB\n",
- loglvl, frame->pc, (void *)frame->pc);
- return 0;
- }
- static void show_trace(struct task_struct *task, unsigned long *sp,
- const char *loglvl)
- {
- if (!sp)
- sp = stack_pointer(task);
- printk("%sCall Trace:\n", loglvl);
- walk_stackframe(sp, show_trace_cb, (void *)loglvl);
- }
- #define STACK_DUMP_ENTRY_SIZE 4
- #define STACK_DUMP_LINE_SIZE 32
- static size_t kstack_depth_to_print = CONFIG_PRINT_STACK_DEPTH;
- void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
- {
- size_t len, off = 0;
- if (!sp)
- sp = stack_pointer(task);
- len = min((-(size_t)sp) & (THREAD_SIZE - STACK_DUMP_ENTRY_SIZE),
- kstack_depth_to_print * STACK_DUMP_ENTRY_SIZE);
- printk("%sStack:\n", loglvl);
- while (off < len) {
- u8 line[STACK_DUMP_LINE_SIZE];
- size_t line_len = len - off > STACK_DUMP_LINE_SIZE ?
- STACK_DUMP_LINE_SIZE : len - off;
- __memcpy(line, (u8 *)sp + off, line_len);
- print_hex_dump(loglvl, " ", DUMP_PREFIX_NONE,
- STACK_DUMP_LINE_SIZE, STACK_DUMP_ENTRY_SIZE,
- line, line_len, false);
- off += STACK_DUMP_LINE_SIZE;
- }
- show_trace(task, sp, loglvl);
- }
- DEFINE_SPINLOCK(die_lock);
- void __noreturn die(const char * str, struct pt_regs * regs, long err)
- {
- static int die_counter;
- const char *pr = "";
- if (IS_ENABLED(CONFIG_PREEMPTION))
- pr = IS_ENABLED(CONFIG_PREEMPT_RT) ? " PREEMPT_RT" : " PREEMPT";
- console_verbose();
- spin_lock_irq(&die_lock);
- pr_info("%s: sig: %ld [#%d]%s\n", str, err, ++die_counter, pr);
- show_regs(regs);
- if (!user_mode(regs))
- show_stack(NULL, (unsigned long *)regs->areg[1], KERN_INFO);
- add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
- spin_unlock_irq(&die_lock);
- if (in_interrupt())
- panic("Fatal exception in interrupt");
- if (panic_on_oops)
- panic("Fatal exception");
- make_task_dead(err);
- }
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