// 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/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/efi.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 <linux/ubsan.h>
#include <linux/cfi.h>
#include <asm/atomic.h>
#include <asm/bug.h>
#include <asm/cpufeature.h>
#include <asm/daifflags.h>
#include <asm/debug-monitors.h>
#include <asm/efi.h>
#include <asm/esr.h>
#include <asm/exception.h>
#include <asm/extable.h>
#include <asm/insn.h>
#include <asm/kprobes.h>
#include <asm/patching.h>
#include <asm/traps.h>
#include <asm/smp.h>
#include <asm/stack_pointer.h>
#include <asm/stacktrace.h>
#include <asm/system_misc.h>
#include <asm/sysreg.h>
static bool __kprobes __check_eq(unsigned long pstate)
{
return (pstate & PSR_Z_BIT) != 0;
}
static bool __kprobes __check_ne(unsigned long pstate)
{
return (pstate & PSR_Z_BIT) == 0;
}
static bool __kprobes __check_cs(unsigned long pstate)
{
return (pstate & PSR_C_BIT) != 0;
}
static bool __kprobes __check_cc(unsigned long pstate)
{
return (pstate & PSR_C_BIT) == 0;
}
static bool __kprobes __check_mi(unsigned long pstate)
{
return (pstate & PSR_N_BIT) != 0;
}
static bool __kprobes __check_pl(unsigned long pstate)
{
return (pstate & PSR_N_BIT) == 0;
}
static bool __kprobes __check_vs(unsigned long pstate)
{
return (pstate & PSR_V_BIT) != 0;
}
static bool __kprobes __check_vc(unsigned long pstate)
{
return (pstate & PSR_V_BIT) == 0;
}
static bool __kprobes __check_hi(unsigned long pstate)
{
pstate &= ~(pstate >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */
return (pstate & PSR_C_BIT) != 0;
}
static bool __kprobes __check_ls(unsigned long pstate)
{
pstate &= ~(pstate >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */
return (pstate & PSR_C_BIT) == 0;
}
static bool __kprobes __check_ge(unsigned long pstate)
{
pstate ^= (pstate << 3); /* PSR_N_BIT ^= PSR_V_BIT */
return (pstate & PSR_N_BIT) == 0;
}
static bool __kprobes __check_lt(unsigned long pstate)
{
pstate ^= (pstate << 3); /* PSR_N_BIT ^= PSR_V_BIT */
return (pstate & PSR_N_BIT) != 0;
}
static bool __kprobes __check_gt(unsigned long pstate)
{
/*PSR_N_BIT ^= PSR_V_BIT */
unsigned long temp = pstate ^ (pstate << 3);
temp |= (pstate << 1); /*PSR_N_BIT |= PSR_Z_BIT */
return (temp & PSR_N_BIT) == 0;
}
static bool __kprobes __check_le(unsigned long pstate)
{
/*PSR_N_BIT ^= PSR_V_BIT */
unsigned long temp = pstate ^ (pstate << 3);
temp |= (pstate << 1); /*PSR_N_BIT |= PSR_Z_BIT */
return (temp & PSR_N_BIT) != 0;
}
static bool __kprobes __check_al(unsigned long pstate)
{
return true;
}
/*
* Note that the ARMv8 ARM calls condition code 0b1111 "nv", but states that
* it behaves identically to 0b1110 ("al").
*/
pstate_check_t * const aarch32_opcode_cond_checks[16] = {
__check_eq, __check_ne, __check_cs, __check_cc,
__check_mi, __check_pl, __check_vs, __check_vc,
__check_hi, __check_ls, __check_ge, __check_lt,
__check_gt, __check_le, __check_al, __check_al
};
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, i == 0 ? "(????????) " : "???????? ");
}
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 long 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%016lx, ", 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, unsigned long far,
const char *str)
{
arm64_show_signal(signo, str);
if (signo == SIGKILL)
force_sig(SIGKILL);
else
force_sig_fault(signo, code, (void __user *)far);
}
void arm64_force_sig_mceerr(int code, unsigned long far, short lsb,
const char *str)
{
arm64_show_signal(SIGBUS, str);
force_sig_mceerr(code, (void __user *)far, lsb);
}
void arm64_force_sig_ptrace_errno_trap(int errno, unsigned long far,
const char *str)
{
arm64_show_signal(SIGTRAP, str);
force_sig_ptrace_errno_trap(errno, (void __user *)far);
}
void arm64_notify_die(const char *str, struct pt_regs *regs,
int signo, int sicode, unsigned long far,
unsigned long 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, far, 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;
unsigned long pc = 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 long 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, 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, untagged_addr(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)
{
if (efi_runtime_fixup_exception(regs, "BTI violation")) {
regs->pstate &= ~PSR_BTYPE_MASK;
return;
}
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);
}
void do_el0_mops(struct pt_regs *regs, unsigned long esr)
{
bool wrong_option = esr & ESR_ELx_MOPS_ISS_WRONG_OPTION;
bool option_a = esr & ESR_ELx_MOPS_ISS_OPTION_A;
int dstreg = ESR_ELx_MOPS_ISS_DESTREG(esr);
int srcreg = ESR_ELx_MOPS_ISS_SRCREG(esr);
int sizereg = ESR_ELx_MOPS_ISS_SIZEREG(esr);
unsigned long dst, src, size;
dst = pt_regs_read_reg(regs, dstreg);
src = pt_regs_read_reg(regs, srcreg);
size = pt_regs_read_reg(regs, sizereg);
/*
* Put the registers back in the original format suitable for a
* prologue instruction, using the generic return routine from the
* Arm ARM (DDI 0487I.a) rules CNTMJ and MWFQH.
*/
if (esr & ESR_ELx_MOPS_ISS_MEM_INST) {
/* SET* instruction */
if (option_a ^ wrong_option) {
/* Format is from Option A; forward set */
pt_regs_write_reg(regs, dstreg, dst + size);
pt_regs_write_reg(regs, sizereg, -size);
}
} else {
/* CPY* instruction */
if (!(option_a ^ wrong_option)) {
/* Format is from Option B */
if (regs->pstate & PSR_N_BIT) {
/* Backward copy */
pt_regs_write_reg(regs, dstreg, dst - size);
pt_regs_write_reg(regs, srcreg, src - size);
}
} else {
/* Format is from Option A */
if (size & BIT(63)) {
/* Forward copy */
pt_regs_write_reg(regs, dstreg, dst + size);
pt_regs_write_reg(regs, srcreg, src + size);
pt_regs_write_reg(regs, sizereg, -size);
}
}
}
if (esr & ESR_ELx_MOPS_ISS_FROM_EPILOGUE)
regs->pc -= 8;
else
regs->pc -= 4;
/*
* If single stepping then finish the step before executing the
* prologue instruction.
*/
user_fastforward_single_step(current);
}
#define __user_cache_maint(insn, address, res) \
if (address >= TASK_SIZE_MAX) { \
res = -EFAULT; \
} else { \
uaccess_ttbr0_enable(); \
asm volatile ( \
"1: " insn ", %1\n" \
" mov %w0, #0\n" \
"2:\n" \
_ASM_EXTABLE_UACCESS_ERR(1b, 2b, %w0) \
: "=r" (res) \
: "r" (address)); \
uaccess_ttbr0_disable(); \
}
static void user_cache_maint_handler(unsigned long esr, struct pt_regs *regs)
{
unsigned long tagged_address, 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;
tagged_address = pt_regs_read_reg(regs, rt);
address = untagged_addr(tagged_address);
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(tagged_address);
else
arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
}
static void ctr_read_handler(unsigned long 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_EL0_DIC_SHIFT);
/* ... and fake IminLine to reduce the number of traps. */
val &= ~CTR_EL0_IminLine_MASK;
val |= (PAGE_SHIFT - 2) & CTR_EL0_IminLine_MASK;
}
pt_regs_write_reg(regs, rt, val);
arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
}
static void cntvct_read_handler(unsigned long 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 long 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 long 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 long esr, struct pt_regs *regs)
{
arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
}
struct sys64_hook {
unsigned long esr_mask;
unsigned long esr_val;
void (*handler)(unsigned long 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 CNTVCTSS_EL0 */
.esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK,
.esr_val = ESR_ELx_SYS64_ISS_SYS_CNTVCTSS,
.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 long 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 long 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 long 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,
},
{
.esr_mask = ESR_ELx_CP15_64_ISS_SYS_MASK,
.esr_val = ESR_ELx_CP15_64_ISS_SYS_CNTVCTSS,
.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_SME] = "SME",
[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_MOPS] = "MOPS",
[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(unsigned long esr)
{
return esr_class_str[ESR_ELx_EC(esr)];
}
/*
* bad_el0_sync handles unexpected, but potentially recoverable synchronous
* exceptions taken from EL0.
*/
void bad_el0_sync(struct pt_regs *regs, int reason, unsigned long esr)
{
unsigned long pc = 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);
void __noreturn panic_bad_stack(struct pt_regs *regs, unsigned long esr, unsigned long far)
{
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);
console_verbose();
pr_emerg("Insufficient stack space to handle exception!");
pr_emerg("ESR: 0x%016lx -- %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, unsigned long esr)
{
console_verbose();
pr_crit("SError Interrupt on CPU%d, code 0x%016lx -- %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();
}
bool arm64_is_fatal_ras_serror(struct pt_regs *regs, unsigned long esr)
{
unsigned long 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);
}
}
void do_serror(struct pt_regs *regs, unsigned long esr)
{
/* non-RAS errors are not containable */
if (!arm64_is_ras_serror(esr) || arm64_is_fatal_ras_serror(regs, esr))
arm64_serror_panic(regs, esr);
}
/* GENERIC_BUG traps */
#ifdef CONFIG_GENERIC_BUG
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;
}
#endif
static int bug_handler(struct pt_regs *regs, unsigned long 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,
};
#ifdef CONFIG_CFI_CLANG
static int cfi_handler(struct pt_regs *regs, unsigned long esr)
{
unsigned long target;
u32 type;
target = pt_regs_read_reg(regs, FIELD_GET(CFI_BRK_IMM_TARGET, esr));
type = (u32)pt_regs_read_reg(regs, FIELD_GET(CFI_BRK_IMM_TYPE, esr));
switch (report_cfi_failure(regs, regs->pc, &target, type)) {
case BUG_TRAP_TYPE_BUG:
die("Oops - CFI", regs, esr);
break;
case BUG_TRAP_TYPE_WARN:
break;
default:
return DBG_HOOK_ERROR;
}
arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
return DBG_HOOK_HANDLED;
}
static struct break_hook cfi_break_hook = {
.fn = cfi_handler,
.imm = CFI_BRK_IMM_BASE,
.mask = CFI_BRK_IMM_MASK,
};
#endif /* CONFIG_CFI_CLANG */
static int reserved_fault_handler(struct pt_regs *regs, unsigned long esr)
{
pr_err("%s generated an invalid instruction at %pS!\n",
"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 long esr)
{
bool recover = esr & KASAN_ESR_RECOVER;
bool write = esr & KASAN_ESR_WRITE;
size_t size = KASAN_ESR_SIZE(esr);
void *addr = (void *)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
#ifdef CONFIG_UBSAN_TRAP
static int ubsan_handler(struct pt_regs *regs, unsigned long esr)
{
die(report_ubsan_failure(regs, esr & UBSAN_BRK_MASK), regs, esr);
return DBG_HOOK_HANDLED;
}
static struct break_hook ubsan_break_hook = {
.fn = ubsan_handler,
.imm = UBSAN_BRK_IMM,
.mask = UBSAN_BRK_MASK,
};
#endif
#define esr_comment(esr) ((esr) & ESR_ELx_BRK64_ISS_COMMENT_MASK)
/*
* Initial handler for AArch64 BRK exceptions
* This handler only used until debug_traps_init().
*/
int __init early_brk64(unsigned long addr, unsigned long esr,
struct pt_regs *regs)
{
#ifdef CONFIG_CFI_CLANG
if ((esr_comment(esr) & ~CFI_BRK_IMM_MASK) == CFI_BRK_IMM_BASE)
return cfi_handler(regs, esr) != DBG_HOOK_HANDLED;
#endif
#ifdef CONFIG_KASAN_SW_TAGS
if ((esr_comment(esr) & ~KASAN_BRK_MASK) == KASAN_BRK_IMM)
return kasan_handler(regs, esr) != DBG_HOOK_HANDLED;
#endif
#ifdef CONFIG_UBSAN_TRAP
if ((esr_comment(esr) & ~UBSAN_BRK_MASK) == UBSAN_BRK_IMM)
return ubsan_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);
#ifdef CONFIG_CFI_CLANG
register_kernel_break_hook(&cfi_break_hook);
#endif
register_kernel_break_hook(&fault_break_hook);
#ifdef CONFIG_KASAN_SW_TAGS
register_kernel_break_hook(&kasan_break_hook);
#endif
#ifdef CONFIG_UBSAN_TRAP
register_kernel_break_hook(&ubsan_break_hook);
#endif
debug_traps_init();
}