// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/arch/arm/kernel/traps.c
*
* Copyright (C) 1995-2009 Russell King
* Fragments that appear the same as linux/arch/i386/kernel/traps.c (C) Linus Torvalds
*
* 'traps.c' handles hardware exceptions after we have saved some state in
* 'linux/arch/arm/lib/traps.S'. Mostly a debugging aid, but will probably
* kill the offending process.
*/
#include <linux/signal.h>
#include <linux/personality.h>
#include <linux/kallsyms.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
#include <linux/hardirq.h>
#include <linux/kdebug.h>
#include <linux/kprobes.h>
#include <linux/module.h>
#include <linux/kexec.h>
#include <linux/bug.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/irq.h>
#include <linux/vmalloc.h>
#include <linux/atomic.h>
#include <asm/cacheflush.h>
#include <asm/exception.h>
#include <asm/spectre.h>
#include <asm/unistd.h>
#include <asm/traps.h>
#include <asm/ptrace.h>
#include <asm/unwind.h>
#include <asm/tls.h>
#include <asm/stacktrace.h>
#include <asm/system_misc.h>
#include <asm/opcodes.h>
static const char *handler[]= {
"prefetch abort",
"data abort",
"address exception",
"interrupt",
"undefined instruction",
};
void *vectors_page;
#ifdef CONFIG_DEBUG_USER
unsigned int user_debug;
static int __init user_debug_setup(char *str)
{
get_option(&str, &user_debug);
return 1;
}
__setup("user_debug=", user_debug_setup);
#endif
void dump_backtrace_entry(unsigned long where, unsigned long from,
unsigned long frame, const char *loglvl)
{
unsigned long end = frame + 4 + sizeof(struct pt_regs);
if (IS_ENABLED(CONFIG_UNWINDER_FRAME_POINTER) &&
IS_ENABLED(CONFIG_CC_IS_GCC) &&
end > ALIGN(frame, THREAD_SIZE)) {
/*
* If we are walking past the end of the stack, it may be due
* to the fact that we are on an IRQ or overflow stack. In this
* case, we can load the address of the other stack from the
* frame record.
*/
frame = ((unsigned long *)frame)[-2] - 4;
end = frame + 4 + sizeof(struct pt_regs);
}
#ifndef CONFIG_KALLSYMS
printk("%sFunction entered at [<%08lx>] from [<%08lx>]\n",
loglvl, where, from);
#elif defined CONFIG_BACKTRACE_VERBOSE
printk("%s[<%08lx>] (%ps) from [<%08lx>] (%pS)\n",
loglvl, where, (void *)where, from, (void *)from);
#else
printk("%s %ps from %pS\n", loglvl, (void *)where, (void *)from);
#endif
if (in_entry_text(from) && end <= ALIGN(frame, THREAD_SIZE))
dump_mem(loglvl, "Exception stack", frame + 4, end);
}
void dump_backtrace_stm(u32 *stack, u32 instruction, const char *loglvl)
{
char str[80], *p;
unsigned int x;
int reg;
for (reg = 10, x = 0, p = str; reg >= 0; reg--) {
if (instruction & BIT(reg)) {
p += sprintf(p, " r%d:%08x", reg, *stack--);
if (++x == 6) {
x = 0;
p = str;
printk("%s%s\n", loglvl, str);
}
}
}
if (p != str)
printk("%s%s\n", loglvl, str);
}
#ifndef CONFIG_ARM_UNWIND
/*
* Stack pointers should always be within the kernels view of
* physical memory. If it is not there, then we can't dump
* out any information relating to the stack.
*/
static int verify_stack(unsigned long sp)
{
if (sp < PAGE_OFFSET ||
(!IS_ENABLED(CONFIG_VMAP_STACK) &&
sp > (unsigned long)high_memory && high_memory != NULL))
return -EFAULT;
return 0;
}
#endif
/*
* Dump out the contents of some memory nicely...
*/
void dump_mem(const char *lvl, const char *str, unsigned long bottom,
unsigned long top)
{
unsigned long first;
int i;
printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
for (first = bottom & ~31; first < top; first += 32) {
unsigned long p;
char str[sizeof(" 12345678") * 8 + 1];
memset(str, ' ', sizeof(str));
str[sizeof(str) - 1] = '\0';
for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
if (p >= bottom && p < top) {
unsigned long val;
if (!get_kernel_nofault(val, (unsigned long *)p))
sprintf(str + i * 9, " %08lx", val);
else
sprintf(str + i * 9, " ????????");
}
}
printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
}
}
static void dump_instr(const char *lvl, struct pt_regs *regs)
{
unsigned long addr = instruction_pointer(regs);
const int thumb = thumb_mode(regs);
const int width = thumb ? 4 : 8;
char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
int i;
/*
* Note that we now dump the code first, just in case the backtrace
* kills us.
*/
for (i = -4; i < 1 + !!thumb; i++) {
unsigned int val, bad;
if (thumb) {
u16 tmp;
if (user_mode(regs))
bad = get_user(tmp, &((u16 __user *)addr)[i]);
else
bad = get_kernel_nofault(tmp, &((u16 *)addr)[i]);
val = __mem_to_opcode_thumb16(tmp);
} else {
if (user_mode(regs))
bad = get_user(val, &((u32 __user *)addr)[i]);
else
bad = get_kernel_nofault(val, &((u32 *)addr)[i]);
val = __mem_to_opcode_arm(val);
}
if (!bad)
p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
width, val);
else {
p += sprintf(p, "bad PC value");
break;
}
}
printk("%sCode: %s\n", lvl, str);
}
#ifdef CONFIG_ARM_UNWIND
void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
const char *loglvl)
{
unwind_backtrace(regs, tsk, loglvl);
}
#else
void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
const char *loglvl)
{
unsigned int fp, mode;
int ok = 1;
printk("%sCall trace: ", loglvl);
if (!tsk)
tsk = current;
if (regs) {
fp = frame_pointer(regs);
mode = processor_mode(regs);
} else if (tsk != current) {
fp = thread_saved_fp(tsk);
mode = 0x10;
} else {
asm("mov %0, fp" : "=r" (fp) : : "cc");
mode = 0x10;
}
if (!fp) {
pr_cont("no frame pointer");
ok = 0;
} else if (verify_stack(fp)) {
pr_cont("invalid frame pointer 0x%08x", fp);
ok = 0;
} else if (fp < (unsigned long)end_of_stack(tsk))
pr_cont("frame pointer underflow");
pr_cont("\n");
if (ok)
c_backtrace(fp, mode, loglvl);
}
#endif
void show_stack(struct task_struct *tsk, unsigned long *sp, const char *loglvl)
{
dump_backtrace(NULL, tsk, loglvl);
barrier();
}
#ifdef CONFIG_PREEMPT
#define S_PREEMPT " PREEMPT"
#elif defined(CONFIG_PREEMPT_RT)
#define S_PREEMPT " PREEMPT_RT"
#else
#define S_PREEMPT ""
#endif
#ifdef CONFIG_SMP
#define S_SMP " SMP"
#else
#define S_SMP ""
#endif
#ifdef CONFIG_THUMB2_KERNEL
#define S_ISA " THUMB2"
#else
#define S_ISA " ARM"
#endif
static int __die(const char *str, int err, struct pt_regs *regs)
{
struct task_struct *tsk = current;
static int die_counter;
int ret;
pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP S_ISA "\n",
str, err, ++die_counter);
/* trap and error numbers are mostly meaningless on ARM */
ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
if (ret == NOTIFY_STOP)
return 1;
print_modules();
__show_regs(regs);
__show_regs_alloc_free(regs);
pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
if (!user_mode(regs) || in_interrupt()) {
dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
ALIGN(regs->ARM_sp - THREAD_SIZE, THREAD_ALIGN)
+ THREAD_SIZE);
dump_backtrace(regs, tsk, KERN_EMERG);
dump_instr(KERN_EMERG, regs);
}
return 0;
}
static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
static int die_owner = -1;
static unsigned int die_nest_count;
static unsigned long oops_begin(void)
{
int cpu;
unsigned long flags;
oops_enter();
/* racy, but better than risking deadlock. */
raw_local_irq_save(flags);
cpu = smp_processor_id();
if (!arch_spin_trylock(&die_lock)) {
if (cpu == die_owner)
/* nested oops. should stop eventually */;
else
arch_spin_lock(&die_lock);
}
die_nest_count++;
die_owner = cpu;
console_verbose();
bust_spinlocks(1);
return flags;
}
static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
{
if (regs && kexec_should_crash(current))
crash_kexec(regs);
bust_spinlocks(0);
die_owner = -1;
add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
die_nest_count--;
if (!die_nest_count)
/* Nest count reaches zero, release the lock. */
arch_spin_unlock(&die_lock);
raw_local_irq_restore(flags);
oops_exit();
if (in_interrupt())
panic("Fatal exception in interrupt");
if (panic_on_oops)
panic("Fatal exception");
if (signr)
make_task_dead(signr);
}
/*
* This function is protected against re-entrancy.
*/
void die(const char *str, struct pt_regs *regs, int err)
{
enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
unsigned long flags = oops_begin();
int sig = SIGSEGV;
if (!user_mode(regs))
bug_type = report_bug(regs->ARM_pc, regs);
if (bug_type != BUG_TRAP_TYPE_NONE)
str = "Oops - BUG";
if (__die(str, err, regs))
sig = 0;
oops_end(flags, regs, sig);
}
void arm_notify_die(const char *str, struct pt_regs *regs,
int signo, int si_code, void __user *addr,
unsigned long err, unsigned long trap)
{
if (user_mode(regs)) {
current->thread.error_code = err;
current->thread.trap_no = trap;
force_sig_fault(signo, si_code, addr);
} else {
die(str, regs, err);
}
}
#ifdef CONFIG_GENERIC_BUG
int is_valid_bugaddr(unsigned long pc)
{
#ifdef CONFIG_THUMB2_KERNEL
u16 bkpt;
u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
#else
u32 bkpt;
u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
#endif
if (get_kernel_nofault(bkpt, (void *)pc))
return 0;
return bkpt == insn;
}
#endif
static LIST_HEAD(undef_hook);
static DEFINE_RAW_SPINLOCK(undef_lock);
void register_undef_hook(struct undef_hook *hook)
{
unsigned long flags;
raw_spin_lock_irqsave(&undef_lock, flags);
list_add(&hook->node, &undef_hook);
raw_spin_unlock_irqrestore(&undef_lock, flags);
}
void unregister_undef_hook(struct undef_hook *hook)
{
unsigned long flags;
raw_spin_lock_irqsave(&undef_lock, flags);
list_del(&hook->node);
raw_spin_unlock_irqrestore(&undef_lock, flags);
}
static nokprobe_inline
int call_undef_hook(struct pt_regs *regs, unsigned int instr)
{
struct undef_hook *hook;
unsigned long flags;
int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
raw_spin_lock_irqsave(&undef_lock, flags);
list_for_each_entry(hook, &undef_hook, node)
if ((instr & hook->instr_mask) == hook->instr_val &&
(regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
fn = hook->fn;
raw_spin_unlock_irqrestore(&undef_lock, flags);
return fn ? fn(regs, instr) : 1;
}
asmlinkage void do_undefinstr(struct pt_regs *regs)
{
unsigned int instr;
void __user *pc;
pc = (void __user *)instruction_pointer(regs);
if (processor_mode(regs) == SVC_MODE) {
#ifdef CONFIG_THUMB2_KERNEL
if (thumb_mode(regs)) {
instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
if (is_wide_instruction(instr)) {
u16 inst2;
inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
instr = __opcode_thumb32_compose(instr, inst2);
}
} else
#endif
instr = __mem_to_opcode_arm(*(u32 *) pc);
} else if (thumb_mode(regs)) {
if (get_user(instr, (u16 __user *)pc))
goto die_sig;
instr = __mem_to_opcode_thumb16(instr);
if (is_wide_instruction(instr)) {
unsigned int instr2;
if (get_user(instr2, (u16 __user *)pc+1))
goto die_sig;
instr2 = __mem_to_opcode_thumb16(instr2);
instr = __opcode_thumb32_compose(instr, instr2);
}
} else {
if (get_user(instr, (u32 __user *)pc))
goto die_sig;
instr = __mem_to_opcode_arm(instr);
}
if (call_undef_hook(regs, instr) == 0)
return;
die_sig:
#ifdef CONFIG_DEBUG_USER
if (user_debug & UDBG_UNDEFINED) {
pr_info("%s (%d): undefined instruction: pc=%px\n",
current->comm, task_pid_nr(current), pc);
__show_regs(regs);
dump_instr(KERN_INFO, regs);
}
#endif
arm_notify_die("Oops - undefined instruction", regs,
SIGILL, ILL_ILLOPC, pc, 0, 6);
}
NOKPROBE_SYMBOL(do_undefinstr)
/*
* Handle FIQ similarly to NMI on x86 systems.
*
* The runtime environment for NMIs is extremely restrictive
* (NMIs can pre-empt critical sections meaning almost all locking is
* forbidden) meaning this default FIQ handling must only be used in
* circumstances where non-maskability improves robustness, such as
* watchdog or debug logic.
*
* This handler is not appropriate for general purpose use in drivers
* platform code and can be overrideen using set_fiq_handler.
*/
asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
{
struct pt_regs *old_regs = set_irq_regs(regs);
nmi_enter();
/* nop. FIQ handlers for special arch/arm features can be added here. */
nmi_exit();
set_irq_regs(old_regs);
}
/*
* bad_mode handles the impossible case in the vectors. If you see one of
* these, then it's extremely serious, and could mean you have buggy hardware.
* It never returns, and never tries to sync. We hope that we can at least
* dump out some state information...
*/
asmlinkage void bad_mode(struct pt_regs *regs, int reason)
{
console_verbose();
pr_crit("Bad mode in %s handler detected\n", handler[reason]);
die("Oops - bad mode", regs, 0);
local_irq_disable();
panic("bad mode");
}
static int bad_syscall(int n, struct pt_regs *regs)
{
if ((current->personality & PER_MASK) != PER_LINUX) {
send_sig(SIGSEGV, current, 1);
return regs->ARM_r0;
}
#ifdef CONFIG_DEBUG_USER
if (user_debug & UDBG_SYSCALL) {
pr_err("[%d] %s: obsolete system call %08x.\n",
task_pid_nr(current), current->comm, n);
dump_instr(KERN_ERR, regs);
}
#endif
arm_notify_die("Oops - bad syscall", regs, SIGILL, ILL_ILLTRP,
(void __user *)instruction_pointer(regs) -
(thumb_mode(regs) ? 2 : 4),
n, 0);
return regs->ARM_r0;
}
static inline int
__do_cache_op(unsigned long start, unsigned long end)
{
int ret;
do {
unsigned long chunk = min(PAGE_SIZE, end - start);
if (fatal_signal_pending(current))
return 0;
ret = flush_icache_user_range(start, start + chunk);
if (ret)
return ret;
cond_resched();
start += chunk;
} while (start < end);
return 0;
}
static inline int
do_cache_op(unsigned long start, unsigned long end, int flags)
{
if (end < start || flags)
return -EINVAL;
if (!access_ok((void __user *)start, end - start))
return -EFAULT;
return __do_cache_op(start, end);
}
/*
* Handle all unrecognised system calls.
* 0x9f0000 - 0x9fffff are some more esoteric system calls
*/
#define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
asmlinkage int arm_syscall(int no, struct pt_regs *regs)
{
if ((no >> 16) != (__ARM_NR_BASE>> 16))
return bad_syscall(no, regs);
switch (no & 0xffff) {
case 0: /* branch through 0 */
arm_notify_die("branch through zero", regs,
SIGSEGV, SEGV_MAPERR, NULL, 0, 0);
return 0;
case NR(breakpoint): /* SWI BREAK_POINT */
regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
ptrace_break(regs);
return regs->ARM_r0;
/*
* Flush a region from virtual address 'r0' to virtual address 'r1'
* _exclusive_. There is no alignment requirement on either address;
* user space does not need to know the hardware cache layout.
*
* r2 contains flags. It should ALWAYS be passed as ZERO until it
* is defined to be something else. For now we ignore it, but may
* the fires of hell burn in your belly if you break this rule. ;)
*
* (at a later date, we may want to allow this call to not flush
* various aspects of the cache. Passing '0' will guarantee that
* everything necessary gets flushed to maintain consistency in
* the specified region).
*/
case NR(cacheflush):
return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
case NR(usr26):
if (!(elf_hwcap & HWCAP_26BIT))
break;
regs->ARM_cpsr &= ~MODE32_BIT;
return regs->ARM_r0;
case NR(usr32):
if (!(elf_hwcap & HWCAP_26BIT))
break;
regs->ARM_cpsr |= MODE32_BIT;
return regs->ARM_r0;
case NR(set_tls):
set_tls(regs->ARM_r0);
return 0;
case NR(get_tls):
return current_thread_info()->tp_value[0];
default:
/* Calls 9f00xx..9f07ff are defined to return -ENOSYS
if not implemented, rather than raising SIGILL. This
way the calling program can gracefully determine whether
a feature is supported. */
if ((no & 0xffff) <= 0x7ff)
return -ENOSYS;
break;
}
#ifdef CONFIG_DEBUG_USER
/*
* experience shows that these seem to indicate that
* something catastrophic has happened
*/
if (user_debug & UDBG_SYSCALL) {
pr_err("[%d] %s: arm syscall %d\n",
task_pid_nr(current), current->comm, no);
dump_instr(KERN_ERR, regs);
if (user_mode(regs)) {
__show_regs(regs);
c_backtrace(frame_pointer(regs), processor_mode(regs), KERN_ERR);
}
}
#endif
arm_notify_die("Oops - bad syscall(2)", regs, SIGILL, ILL_ILLTRP,
(void __user *)instruction_pointer(regs) -
(thumb_mode(regs) ? 2 : 4),
no, 0);
return 0;
}
#ifdef CONFIG_TLS_REG_EMUL
/*
* We might be running on an ARMv6+ processor which should have the TLS
* register but for some reason we can't use it, or maybe an SMP system
* using a pre-ARMv6 processor (there are apparently a few prototypes like
* that in existence) and therefore access to that register must be
* emulated.
*/
static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
{
int reg = (instr >> 12) & 15;
if (reg == 15)
return 1;
regs->uregs[reg] = current_thread_info()->tp_value[0];
regs->ARM_pc += 4;
return 0;
}
static struct undef_hook arm_mrc_hook = {
.instr_mask = 0x0fff0fff,
.instr_val = 0x0e1d0f70,
.cpsr_mask = PSR_T_BIT,
.cpsr_val = 0,
.fn = get_tp_trap,
};
static int __init arm_mrc_hook_init(void)
{
register_undef_hook(&arm_mrc_hook);
return 0;
}
late_initcall(arm_mrc_hook_init);
#endif
/*
* A data abort trap was taken, but we did not handle the instruction.
* Try to abort the user program, or panic if it was the kernel.
*/
asmlinkage void
baddataabort(int code, unsigned long instr, struct pt_regs *regs)
{
unsigned long addr = instruction_pointer(regs);
#ifdef CONFIG_DEBUG_USER
if (user_debug & UDBG_BADABORT) {
pr_err("8<--- cut here ---\n");
pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n",
task_pid_nr(current), current->comm, code, instr);
dump_instr(KERN_ERR, regs);
show_pte(KERN_ERR, current->mm, addr);
}
#endif
arm_notify_die("unknown data abort code", regs,
SIGILL, ILL_ILLOPC, (void __user *)addr, instr, 0);
}
void __readwrite_bug(const char *fn)
{
pr_err("%s called, but not implemented\n", fn);
BUG();
}
EXPORT_SYMBOL(__readwrite_bug);
#ifdef CONFIG_MMU
void __pte_error(const char *file, int line, pte_t pte)
{
pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
}
void __pmd_error(const char *file, int line, pmd_t pmd)
{
pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
}
void __pgd_error(const char *file, int line, pgd_t pgd)
{
pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
}
#endif
asmlinkage void __div0(void)
{
pr_err("Division by zero in kernel.\n");
dump_stack();
}
EXPORT_SYMBOL(__div0);
void abort(void)
{
BUG();
/* if that doesn't kill us, halt */
panic("Oops failed to kill thread");
}
#ifdef CONFIG_KUSER_HELPERS
static void __init kuser_init(void *vectors)
{
extern char __kuser_helper_start[], __kuser_helper_end[];
int kuser_sz = __kuser_helper_end - __kuser_helper_start;
memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
/*
* vectors + 0xfe0 = __kuser_get_tls
* vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
*/
if (tls_emu || has_tls_reg)
memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
}
#else
static inline void __init kuser_init(void *vectors)
{
}
#endif
#ifndef CONFIG_CPU_V7M
static void copy_from_lma(void *vma, void *lma_start, void *lma_end)
{
memcpy(vma, lma_start, lma_end - lma_start);
}
static void flush_vectors(void *vma, size_t offset, size_t size)
{
unsigned long start = (unsigned long)vma + offset;
unsigned long end = start + size;
flush_icache_range(start, end);
}
#ifdef CONFIG_HARDEN_BRANCH_HISTORY
int spectre_bhb_update_vectors(unsigned int method)
{
extern char __vectors_bhb_bpiall_start[], __vectors_bhb_bpiall_end[];
extern char __vectors_bhb_loop8_start[], __vectors_bhb_loop8_end[];
void *vec_start, *vec_end;
if (system_state >= SYSTEM_FREEING_INITMEM) {
pr_err("CPU%u: Spectre BHB workaround too late - system vulnerable\n",
smp_processor_id());
return SPECTRE_VULNERABLE;
}
switch (method) {
case SPECTRE_V2_METHOD_LOOP8:
vec_start = __vectors_bhb_loop8_start;
vec_end = __vectors_bhb_loop8_end;
break;
case SPECTRE_V2_METHOD_BPIALL:
vec_start = __vectors_bhb_bpiall_start;
vec_end = __vectors_bhb_bpiall_end;
break;
default:
pr_err("CPU%u: unknown Spectre BHB state %d\n",
smp_processor_id(), method);
return SPECTRE_VULNERABLE;
}
copy_from_lma(vectors_page, vec_start, vec_end);
flush_vectors(vectors_page, 0, vec_end - vec_start);
return SPECTRE_MITIGATED;
}
#endif
void __init early_trap_init(void *vectors_base)
{
extern char __stubs_start[], __stubs_end[];
extern char __vectors_start[], __vectors_end[];
unsigned i;
vectors_page = vectors_base;
/*
* Poison the vectors page with an undefined instruction. This
* instruction is chosen to be undefined for both ARM and Thumb
* ISAs. The Thumb version is an undefined instruction with a
* branch back to the undefined instruction.
*/
for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
((u32 *)vectors_base)[i] = 0xe7fddef1;
/*
* Copy the vectors, stubs and kuser helpers (in entry-armv.S)
* into the vector page, mapped at 0xffff0000, and ensure these
* are visible to the instruction stream.
*/
copy_from_lma(vectors_base, __vectors_start, __vectors_end);
copy_from_lma(vectors_base + 0x1000, __stubs_start, __stubs_end);
kuser_init(vectors_base);
flush_vectors(vectors_base, 0, PAGE_SIZE * 2);
}
#else /* ifndef CONFIG_CPU_V7M */
void __init early_trap_init(void *vectors_base)
{
/*
* on V7-M there is no need to copy the vector table to a dedicated
* memory area. The address is configurable and so a table in the kernel
* image can be used.
*/
}
#endif
#ifdef CONFIG_VMAP_STACK
DECLARE_PER_CPU(u8 *, irq_stack_ptr);
asmlinkage DEFINE_PER_CPU(u8 *, overflow_stack_ptr);
static int __init allocate_overflow_stacks(void)
{
u8 *stack;
int cpu;
for_each_possible_cpu(cpu) {
stack = (u8 *)__get_free_page(GFP_KERNEL);
if (WARN_ON(!stack))
return -ENOMEM;
per_cpu(overflow_stack_ptr, cpu) = &stack[OVERFLOW_STACK_SIZE];
}
return 0;
}
early_initcall(allocate_overflow_stacks);
asmlinkage void handle_bad_stack(struct pt_regs *regs)
{
unsigned long tsk_stk = (unsigned long)current->stack;
#ifdef CONFIG_IRQSTACKS
unsigned long irq_stk = (unsigned long)raw_cpu_read(irq_stack_ptr);
#endif
unsigned long ovf_stk = (unsigned long)raw_cpu_read(overflow_stack_ptr);
console_verbose();
pr_emerg("Insufficient stack space to handle exception!");
pr_emerg("Task stack: [0x%08lx..0x%08lx]\n",
tsk_stk, tsk_stk + THREAD_SIZE);
#ifdef CONFIG_IRQSTACKS
pr_emerg("IRQ stack: [0x%08lx..0x%08lx]\n",
irq_stk - THREAD_SIZE, irq_stk);
#endif
pr_emerg("Overflow stack: [0x%08lx..0x%08lx]\n",
ovf_stk - OVERFLOW_STACK_SIZE, ovf_stk);
die("kernel stack overflow", regs, 0);
}
#ifndef CONFIG_ARM_LPAE
/*
* Normally, we rely on the logic in do_translation_fault() to update stale PMD
* entries covering the vmalloc space in a task's page tables when it first
* accesses the region in question. Unfortunately, this is not sufficient when
* the task stack resides in the vmalloc region, as do_translation_fault() is a
* C function that needs a stack to run.
*
* So we need to ensure that these PMD entries are up to date *before* the MM
* switch. As we already have some logic in the MM switch path that takes care
* of this, let's trigger it by bumping the counter every time the core vmalloc
* code modifies a PMD entry in the vmalloc region. Use release semantics on
* the store so that other CPUs observing the counter's new value are
* guaranteed to see the updated page table entries as well.
*/
void arch_sync_kernel_mappings(unsigned long start, unsigned long end)
{
if (start < VMALLOC_END && end > VMALLOC_START)
atomic_inc_return_release(&init_mm.context.vmalloc_seq);
}
#endif
#endif
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