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fault.c 26.22 KiB
// SPDX-License-Identifier: GPL-2.0-only
/*
* Based on arch/arm/mm/fault.c
*
* Copyright (C) 1995 Linus Torvalds
* Copyright (C) 1995-2004 Russell King
* Copyright (C) 2012 ARM Ltd.
*/
#include <linux/acpi.h>
#include <linux/bitfield.h>
#include <linux/extable.h>
#include <linux/signal.h>
#include <linux/mm.h>
#include <linux/hardirq.h>
#include <linux/init.h>
#include <linux/kprobes.h>
#include <linux/uaccess.h>
#include <linux/page-flags.h>
#include <linux/sched/signal.h>
#include <linux/sched/debug.h>
#include <linux/highmem.h>
#include <linux/perf_event.h>
#include <linux/preempt.h>
#include <linux/hugetlb.h>
#include <asm/acpi.h>
#include <asm/bug.h>
#include <asm/cmpxchg.h>
#include <asm/cpufeature.h>
#include <asm/exception.h>
#include <asm/daifflags.h>
#include <asm/debug-monitors.h>
#include <asm/esr.h>
#include <asm/kasan.h>
#include <asm/sysreg.h>
#include <asm/system_misc.h>
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
#include <asm/traps.h>
struct fault_info {
int (*fn)(unsigned long addr, unsigned int esr,
struct pt_regs *regs);
int sig;
int code;
const char *name;
};
static const struct fault_info fault_info[];
static struct fault_info debug_fault_info[];
static inline const struct fault_info *esr_to_fault_info(unsigned int esr)
{
return fault_info + (esr & ESR_ELx_FSC);
}
static inline const struct fault_info *esr_to_debug_fault_info(unsigned int esr)
{
return debug_fault_info + DBG_ESR_EVT(esr);
}
static void data_abort_decode(unsigned int esr)
{
pr_alert("Data abort info:\n");
if (esr & ESR_ELx_ISV) {
pr_alert(" Access size = %u byte(s)\n",
1U << ((esr & ESR_ELx_SAS) >> ESR_ELx_SAS_SHIFT));
pr_alert(" SSE = %lu, SRT = %lu\n", (esr & ESR_ELx_SSE) >> ESR_ELx_SSE_SHIFT,
(esr & ESR_ELx_SRT_MASK) >> ESR_ELx_SRT_SHIFT);
pr_alert(" SF = %lu, AR = %lu\n",
(esr & ESR_ELx_SF) >> ESR_ELx_SF_SHIFT,
(esr & ESR_ELx_AR) >> ESR_ELx_AR_SHIFT);
} else {
pr_alert(" ISV = 0, ISS = 0x%08lx\n", esr & ESR_ELx_ISS_MASK);
}
pr_alert(" CM = %lu, WnR = %lu\n",
(esr & ESR_ELx_CM) >> ESR_ELx_CM_SHIFT,
(esr & ESR_ELx_WNR) >> ESR_ELx_WNR_SHIFT);
}
static void mem_abort_decode(unsigned int esr)
{
pr_alert("Mem abort info:\n");
pr_alert(" ESR = 0x%08x\n", esr);
pr_alert(" EC = 0x%02lx: %s, IL = %u bits\n",
ESR_ELx_EC(esr), esr_get_class_string(esr),
(esr & ESR_ELx_IL) ? 32 : 16);
pr_alert(" SET = %lu, FnV = %lu\n",
(esr & ESR_ELx_SET_MASK) >> ESR_ELx_SET_SHIFT,
(esr & ESR_ELx_FnV) >> ESR_ELx_FnV_SHIFT);
pr_alert(" EA = %lu, S1PTW = %lu\n",
(esr & ESR_ELx_EA) >> ESR_ELx_EA_SHIFT,
(esr & ESR_ELx_S1PTW) >> ESR_ELx_S1PTW_SHIFT);
if (esr_is_data_abort(esr))
data_abort_decode(esr);
}
static inline bool is_ttbr0_addr(unsigned long addr)
{
/* entry assembly clears tags for TTBR0 addrs */
return addr < TASK_SIZE;
}
static inline bool is_ttbr1_addr(unsigned long addr)
{
/* TTBR1 addresses may have a tag if KASAN_SW_TAGS is in use */
return arch_kasan_reset_tag(addr) >= PAGE_OFFSET;
}
static inline unsigned long mm_to_pgd_phys(struct mm_struct *mm)
{
/* Either init_pg_dir or swapper_pg_dir */
if (mm == &init_mm)
return __pa_symbol(mm->pgd);
return (unsigned long)virt_to_phys(mm->pgd);
}
/*
* Dump out the page tables associated with 'addr' in the currently active mm.
*/
static void show_pte(unsigned long addr)
{
struct mm_struct *mm;
pgd_t *pgdp;
pgd_t pgd;
if (is_ttbr0_addr(addr)) {
/* TTBR0 */
mm = current->active_mm;
if (mm == &init_mm) {
pr_alert("[%016lx] user address but active_mm is swapper\n",
addr);
return; }
} else if (is_ttbr1_addr(addr)) {
/* TTBR1 */
mm = &init_mm;
} else {
pr_alert("[%016lx] address between user and kernel address ranges\n",
addr);
return;
}
pr_alert("%s pgtable: %luk pages, %llu-bit VAs, pgdp=%016lx\n",
mm == &init_mm ? "swapper" : "user", PAGE_SIZE / SZ_1K,
vabits_actual, mm_to_pgd_phys(mm));
pgdp = pgd_offset(mm, addr);
pgd = READ_ONCE(*pgdp);
pr_alert("[%016lx] pgd=%016llx", addr, pgd_val(pgd));
do {
pud_t *pudp, pud;
pmd_t *pmdp, pmd;
pte_t *ptep, pte;
if (pgd_none(pgd) || pgd_bad(pgd))
break;
pudp = pud_offset(pgdp, addr);
pud = READ_ONCE(*pudp);
pr_cont(", pud=%016llx", pud_val(pud));
if (pud_none(pud) || pud_bad(pud))
break;
pmdp = pmd_offset(pudp, addr);
pmd = READ_ONCE(*pmdp);
pr_cont(", pmd=%016llx", pmd_val(pmd));
if (pmd_none(pmd) || pmd_bad(pmd))
break;
ptep = pte_offset_map(pmdp, addr);
pte = READ_ONCE(*ptep);
pr_cont(", pte=%016llx", pte_val(pte));
pte_unmap(ptep);
} while(0);
pr_cont("\n");
}
/*
* This function sets the access flags (dirty, accessed), as well as write
* permission, and only to a more permissive setting.
*
* It needs to cope with hardware update of the accessed/dirty state by other
* agents in the system and can safely skip the __sync_icache_dcache() call as,
* like set_pte_at(), the PTE is never changed from no-exec to exec here.
*
* Returns whether or not the PTE actually changed.
*/
int ptep_set_access_flags(struct vm_area_struct *vma,
unsigned long address, pte_t *ptep,
pte_t entry, int dirty)
{
pteval_t old_pteval, pteval;
pte_t pte = READ_ONCE(*ptep);
if (pte_same(pte, entry))
return 0;
/* only preserve the access flags and write permission */
pte_val(entry) &= PTE_RDONLY | PTE_AF | PTE_WRITE | PTE_DIRTY;
/* * Setting the flags must be done atomically to avoid racing with the
* hardware update of the access/dirty state. The PTE_RDONLY bit must
* be set to the most permissive (lowest value) of *ptep and entry
* (calculated as: a & b == ~(~a | ~b)).
*/
pte_val(entry) ^= PTE_RDONLY;
pteval = pte_val(pte);
do {
old_pteval = pteval;
pteval ^= PTE_RDONLY;
pteval |= pte_val(entry);
pteval ^= PTE_RDONLY;
pteval = cmpxchg_relaxed(&pte_val(*ptep), old_pteval, pteval);
} while (pteval != old_pteval);
flush_tlb_fix_spurious_fault(vma, address);
return 1;
}
static bool is_el1_instruction_abort(unsigned int esr)
{
return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_CUR;
}
static inline bool is_el1_permission_fault(unsigned long addr, unsigned int esr,
struct pt_regs *regs)
{
unsigned int ec = ESR_ELx_EC(esr);
unsigned int fsc_type = esr & ESR_ELx_FSC_TYPE;
if (ec != ESR_ELx_EC_DABT_CUR && ec != ESR_ELx_EC_IABT_CUR)
return false;
if (fsc_type == ESR_ELx_FSC_PERM)
return true;
if (is_ttbr0_addr(addr) && system_uses_ttbr0_pan())
return fsc_type == ESR_ELx_FSC_FAULT &&
(regs->pstate & PSR_PAN_BIT);
return false;
}
static bool __kprobes is_spurious_el1_translation_fault(unsigned long addr,
unsigned int esr,
struct pt_regs *regs)
{
unsigned long flags;
u64 par, dfsc;
if (ESR_ELx_EC(esr) != ESR_ELx_EC_DABT_CUR ||
(esr & ESR_ELx_FSC_TYPE) != ESR_ELx_FSC_FAULT)
return false;
local_irq_save(flags);
asm volatile("at s1e1r, %0" :: "r" (addr));
isb();
par = read_sysreg(par_el1);
local_irq_restore(flags);
if (!(par & SYS_PAR_EL1_F))
return false;
/*
* If we got a different type of fault from the AT instruction,
* treat the translation fault as spurious.
*/
dfsc = FIELD_GET(SYS_PAR_EL1_FST, par);
return (dfsc & ESR_ELx_FSC_TYPE) != ESR_ELx_FSC_FAULT;
}
static void die_kernel_fault(const char *msg, unsigned long addr,
unsigned int esr, struct pt_regs *regs)
{
bust_spinlocks(1);
pr_alert("Unable to handle kernel %s at virtual address %016lx\n", msg,
addr);
mem_abort_decode(esr);
show_pte(addr);
die("Oops", regs, esr);
bust_spinlocks(0);
do_exit(SIGKILL);
}
static void __do_kernel_fault(unsigned long addr, unsigned int esr,
struct pt_regs *regs)
{
const char *msg;
/*
* Are we prepared to handle this kernel fault?
* We are almost certainly not prepared to handle instruction faults.
*/
if (!is_el1_instruction_abort(esr) && fixup_exception(regs))
return;
if (WARN_RATELIMIT(is_spurious_el1_translation_fault(addr, esr, regs),
"Ignoring spurious kernel translation fault at virtual address %016lx\n", addr))
return;
if (is_el1_permission_fault(addr, esr, regs)) {
if (esr & ESR_ELx_WNR)
msg = "write to read-only memory";
else
msg = "read from unreadable memory";
} else if (addr < PAGE_SIZE) {
msg = "NULL pointer dereference";
} else {
msg = "paging request";
}
die_kernel_fault(msg, addr, esr, regs);
}
static void set_thread_esr(unsigned long address, unsigned int esr)
{
current->thread.fault_address = address;
/*
* If the faulting address is in the kernel, we must sanitize the ESR.
* From userspace's point of view, kernel-only mappings don't exist
* at all, so we report them as level 0 translation faults.
* (This is not quite the way that "no mapping there at all" behaves:
* an alignment fault not caused by the memory type would take
* precedence over translation fault for a real access to empty
* space. Unfortunately we can't easily distinguish "alignment fault
* not caused by memory type" from "alignment fault caused by memory
* type", so we ignore this wrinkle and just return the translation
* fault.)
*/
if (!is_ttbr0_addr(current->thread.fault_address)) {
switch (ESR_ELx_EC(esr)) {
case ESR_ELx_EC_DABT_LOW:
/*
* These bits provide only information about the
* faulting instruction, which userspace knows already.
* We explicitly clear bits which are architecturally * RES0 in case they are given meanings in future.
* We always report the ESR as if the fault was taken
* to EL1 and so ISV and the bits in ISS[23:14] are
* clear. (In fact it always will be a fault to EL1.)
*/
esr &= ESR_ELx_EC_MASK | ESR_ELx_IL |
ESR_ELx_CM | ESR_ELx_WNR;
esr |= ESR_ELx_FSC_FAULT;
break;
case ESR_ELx_EC_IABT_LOW:
/*
* Claim a level 0 translation fault.
* All other bits are architecturally RES0 for faults
* reported with that DFSC value, so we clear them.
*/
esr &= ESR_ELx_EC_MASK | ESR_ELx_IL;
esr |= ESR_ELx_FSC_FAULT;
break;
default:
/*
* This should never happen (entry.S only brings us
* into this code for insn and data aborts from a lower
* exception level). Fail safe by not providing an ESR
* context record at all.
*/
WARN(1, "ESR 0x%x is not DABT or IABT from EL0\n", esr);
esr = 0;
break;
}
}
current->thread.fault_code = esr;
}
static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *regs)
{
/*
* If we are in kernel mode at this point, we have no context to
* handle this fault with.
*/
if (user_mode(regs)) {
const struct fault_info *inf = esr_to_fault_info(esr);
set_thread_esr(addr, esr);
arm64_force_sig_fault(inf->sig, inf->code, (void __user *)addr,
inf->name);
} else {
__do_kernel_fault(addr, esr, regs);
}
}
#define VM_FAULT_BADMAP 0x010000
#define VM_FAULT_BADACCESS 0x020000
static vm_fault_t __do_page_fault(struct mm_struct *mm, unsigned long addr,
unsigned int mm_flags, unsigned long vm_flags)
{
struct vm_area_struct *vma = find_vma(mm, addr);
if (unlikely(!vma))
return VM_FAULT_BADMAP;
/*
* Ok, we have a good vm_area for this memory access, so we can handle
* it.
*/
if (unlikely(vma->vm_start > addr)) {
if (!(vma->vm_flags & VM_GROWSDOWN))
return VM_FAULT_BADMAP;
if (expand_stack(vma, addr)) return VM_FAULT_BADMAP;
}
/*
* Check that the permissions on the VMA allow for the fault which
* occurred.
*/
if (!(vma->vm_flags & vm_flags))
return VM_FAULT_BADACCESS;
return handle_mm_fault(vma, addr & PAGE_MASK, mm_flags);
}
static bool is_el0_instruction_abort(unsigned int esr)
{
return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_LOW;
}
/*
* Note: not valid for EL1 DC IVAC, but we never use that such that it
* should fault. EL0 cannot issue DC IVAC (undef).
*/
static bool is_write_abort(unsigned int esr)
{
return (esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM);
}
static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
struct pt_regs *regs)
{
const struct fault_info *inf;
struct mm_struct *mm = current->mm;
vm_fault_t fault, major = 0;
unsigned long vm_flags = VM_READ | VM_WRITE;
unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
if (kprobe_page_fault(regs, esr))
return 0;
/*
* If we're in an interrupt or have no user context, we must not take
* the fault.
*/
if (faulthandler_disabled() || !mm)
goto no_context;
if (user_mode(regs))
mm_flags |= FAULT_FLAG_USER;
if (is_el0_instruction_abort(esr)) {
vm_flags = VM_EXEC;
mm_flags |= FAULT_FLAG_INSTRUCTION;
} else if (is_write_abort(esr)) {
vm_flags = VM_WRITE;
mm_flags |= FAULT_FLAG_WRITE;
}
if (is_ttbr0_addr(addr) && is_el1_permission_fault(addr, esr, regs)) {
/* regs->orig_addr_limit may be 0 if we entered from EL0 */
if (regs->orig_addr_limit == KERNEL_DS)
die_kernel_fault("access to user memory with fs=KERNEL_DS",
addr, esr, regs);
if (is_el1_instruction_abort(esr))
die_kernel_fault("execution of user memory",
addr, esr, regs);
if (!search_exception_tables(regs->pc))
die_kernel_fault("access to user memory outside uaccess routines",
addr, esr, regs);
}
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
/*
* As per x86, we may deadlock here. However, since the kernel only
* validly references user space from well defined areas of the code,
* we can bug out early if this is from code which shouldn't.
*/
if (!down_read_trylock(&mm->mmap_sem)) {
if (!user_mode(regs) && !search_exception_tables(regs->pc))
goto no_context;
retry:
down_read(&mm->mmap_sem);
} else {
/*
* The above down_read_trylock() might have succeeded in which
* case, we'll have missed the might_sleep() from down_read().
*/
might_sleep();
#ifdef CONFIG_DEBUG_VM
if (!user_mode(regs) && !search_exception_tables(regs->pc)) {
up_read(&mm->mmap_sem);
goto no_context;
}
#endif
}
fault = __do_page_fault(mm, addr, mm_flags, vm_flags);
major |= fault & VM_FAULT_MAJOR;
if (fault & VM_FAULT_RETRY) {
/*
* If we need to retry but a fatal signal is pending,
* handle the signal first. We do not need to release
* the mmap_sem because it would already be released
* in __lock_page_or_retry in mm/filemap.c.
*/
if (fatal_signal_pending(current)) {
if (!user_mode(regs))
goto no_context;
return 0;
}
/*
* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk of
* starvation.
*/
if (mm_flags & FAULT_FLAG_ALLOW_RETRY) {
mm_flags &= ~FAULT_FLAG_ALLOW_RETRY;
mm_flags |= FAULT_FLAG_TRIED;
goto retry;
}
}
up_read(&mm->mmap_sem);
/*
* Handle the "normal" (no error) case first.
*/
if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP |
VM_FAULT_BADACCESS)))) {
/*
* Major/minor page fault accounting is only done
* once. If we go through a retry, it is extremely
* likely that the page will be found in page cache at
* that point.
*/
if (major) {
current->maj_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs,
addr); } else {
current->min_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs,
addr);
}
return 0;
}
/*
* If we are in kernel mode at this point, we have no context to
* handle this fault with.
*/
if (!user_mode(regs))
goto no_context;
if (fault & VM_FAULT_OOM) {
/*
* We ran out of memory, call the OOM killer, and return to
* userspace (which will retry the fault, or kill us if we got
* oom-killed).
*/
pagefault_out_of_memory();
return 0;
}
inf = esr_to_fault_info(esr);
set_thread_esr(addr, esr);
if (fault & VM_FAULT_SIGBUS) {
/*
* We had some memory, but were unable to successfully fix up
* this page fault.
*/
arm64_force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)addr,
inf->name);
} else if (fault & (VM_FAULT_HWPOISON_LARGE | VM_FAULT_HWPOISON)) {
unsigned int lsb;
lsb = PAGE_SHIFT;
if (fault & VM_FAULT_HWPOISON_LARGE)
lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault));
arm64_force_sig_mceerr(BUS_MCEERR_AR, (void __user *)addr, lsb,
inf->name);
} else {
/*
* Something tried to access memory that isn't in our memory
* map.
*/
arm64_force_sig_fault(SIGSEGV,
fault == VM_FAULT_BADACCESS ? SEGV_ACCERR : SEGV_MAPERR,
(void __user *)addr,
inf->name);
}
return 0;
no_context:
__do_kernel_fault(addr, esr, regs);
return 0;
}
static int __kprobes do_translation_fault(unsigned long addr,
unsigned int esr,
struct pt_regs *regs)
{
if (is_ttbr0_addr(addr))
return do_page_fault(addr, esr, regs);
do_bad_area(addr, esr, regs); return 0;
}
static int do_alignment_fault(unsigned long addr, unsigned int esr,
struct pt_regs *regs)
{
do_bad_area(addr, esr, regs);
return 0;
}
static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs)
{
return 1; /* "fault" */
}
static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
{
const struct fault_info *inf;
void __user *siaddr;
inf = esr_to_fault_info(esr);
/*
* Return value ignored as we rely on signal merging.
* Future patches will make this more robust.
*/
apei_claim_sea(regs);
if (esr & ESR_ELx_FnV)
siaddr = NULL;
else
siaddr = (void __user *)addr;
arm64_notify_die(inf->name, regs, inf->sig, inf->code, siaddr, esr);
return 0;
}
static const struct fault_info fault_info[] = {
{ do_bad, SIGKILL, SI_KERNEL, "ttbr address size fault" },
{ do_bad, SIGKILL, SI_KERNEL, "level 1 address size fault" },
{ do_bad, SIGKILL, SI_KERNEL, "level 2 address size fault" },
{ do_bad, SIGKILL, SI_KERNEL, "level 3 address size fault" },
{ do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 0 translation fault" },
{ do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 1 translation fault" },
{ do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 2 translation fault" },
{ do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 3 translation fault" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 8" },
{ do_page_fault, SIGSEGV, SEGV_ACCERR, "level 1 access flag fault" },
{ do_page_fault, SIGSEGV, SEGV_ACCERR, "level 2 access flag fault" },
{ do_page_fault, SIGSEGV, SEGV_ACCERR, "level 3 access flag fault" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 12" },
{ do_page_fault, SIGSEGV, SEGV_ACCERR, "level 1 permission fault" },
{ do_page_fault, SIGSEGV, SEGV_ACCERR, "level 2 permission fault" },
{ do_page_fault, SIGSEGV, SEGV_ACCERR, "level 3 permission fault" },
{ do_sea, SIGBUS, BUS_OBJERR, "synchronous external abort" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 17" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 18" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 19" },
{ do_sea, SIGKILL, SI_KERNEL, "level 0 (translation table walk)" },
{ do_sea, SIGKILL, SI_KERNEL, "level 1 (translation table walk)" },
{ do_sea, SIGKILL, SI_KERNEL, "level 2 (translation table walk)" },
{ do_sea, SIGKILL, SI_KERNEL, "level 3 (translation table walk)" },
{ do_sea, SIGBUS, BUS_OBJERR, "synchronous parity or ECC error" }, // Reserved when RAS is implemented
{ do_bad, SIGKILL, SI_KERNEL, "unknown 25" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 26" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 27" },
{ do_sea, SIGKILL, SI_KERNEL, "level 0 synchronous parity error (translation table walk)" }, // Reserved when RAS is implemented
{ do_sea, SIGKILL, SI_KERNEL, "level 1 synchronous parity error (translation table walk)" }, // Reserved when RAS is implemented
{ do_sea, SIGKILL, SI_KERNEL, "level 2 synchronous parity error (translation table walk)" }, // Reserved when RAS is implemented
{ do_sea, SIGKILL, SI_KERNEL, "level 3 synchronous parity error (translation table walk)" }, // Reserved when RAS is implemented { do_bad, SIGKILL, SI_KERNEL, "unknown 32" },
{ do_alignment_fault, SIGBUS, BUS_ADRALN, "alignment fault" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 34" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 35" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 36" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 37" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 38" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 39" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 40" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 41" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 42" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 43" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 44" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 45" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 46" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 47" },
{ do_bad, SIGKILL, SI_KERNEL, "TLB conflict abort" },
{ do_bad, SIGKILL, SI_KERNEL, "Unsupported atomic hardware update fault" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 50" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 51" },
{ do_bad, SIGKILL, SI_KERNEL, "implementation fault (lockdown abort)" },
{ do_bad, SIGBUS, BUS_OBJERR, "implementation fault (unsupported exclusive)" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 54" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 55" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 56" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 57" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 58" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 59" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 60" },
{ do_bad, SIGKILL, SI_KERNEL, "section domain fault" },
{ do_bad, SIGKILL, SI_KERNEL, "page domain fault" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 63" },
};
asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr,
struct pt_regs *regs)
{
const struct fault_info *inf = esr_to_fault_info(esr);
if (!inf->fn(addr, esr, regs))
return;
if (!user_mode(regs)) {
pr_alert("Unhandled fault at 0x%016lx\n", addr);
mem_abort_decode(esr);
show_pte(addr);
}
arm64_notify_die(inf->name, regs,
inf->sig, inf->code, (void __user *)addr, esr);
}
asmlinkage void __exception do_el0_irq_bp_hardening(void)
{
/* PC has already been checked in entry.S */
arm64_apply_bp_hardening();
}
asmlinkage void __exception do_el0_ia_bp_hardening(unsigned long addr,
unsigned int esr,
struct pt_regs *regs)
{
/*
* We've taken an instruction abort from userspace and not yet
* re-enabled IRQs. If the address is a kernel address, apply
* BP hardening prior to enabling IRQs and pre-emption.
*/
if (!is_ttbr0_addr(addr))
arm64_apply_bp_hardening();
local_daif_restore(DAIF_PROCCTX);
do_mem_abort(addr, esr, regs);
}
asmlinkage void __exception do_sp_pc_abort(unsigned long addr,
unsigned int esr,
struct pt_regs *regs)
{
if (user_mode(regs)) {
if (!is_ttbr0_addr(instruction_pointer(regs)))
arm64_apply_bp_hardening();
local_daif_restore(DAIF_PROCCTX);
}
arm64_notify_die("SP/PC alignment exception", regs,
SIGBUS, BUS_ADRALN, (void __user *)addr, esr);
}
int __init early_brk64(unsigned long addr, unsigned int esr,
struct pt_regs *regs);
/*
* __refdata because early_brk64 is __init, but the reference to it is
* clobbered at arch_initcall time.
* See traps.c and debug-monitors.c:debug_traps_init().
*/
static struct fault_info __refdata debug_fault_info[] = {
{ do_bad, SIGTRAP, TRAP_HWBKPT, "hardware breakpoint" },
{ do_bad, SIGTRAP, TRAP_HWBKPT, "hardware single-step" },
{ do_bad, SIGTRAP, TRAP_HWBKPT, "hardware watchpoint" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 3" },
{ do_bad, SIGTRAP, TRAP_BRKPT, "aarch32 BKPT" },
{ do_bad, SIGKILL, SI_KERNEL, "aarch32 vector catch" },
{ early_brk64, SIGTRAP, TRAP_BRKPT, "aarch64 BRK" },
{ do_bad, SIGKILL, SI_KERNEL, "unknown 7" },
};
void __init hook_debug_fault_code(int nr,
int (*fn)(unsigned long, unsigned int, struct pt_regs *),
int sig, int code, const char *name)
{
BUG_ON(nr < 0 || nr >= ARRAY_SIZE(debug_fault_info));
debug_fault_info[nr].fn = fn;
debug_fault_info[nr].sig = sig;
debug_fault_info[nr].code = code;
debug_fault_info[nr].name = name;
}
/*
* In debug exception context, we explicitly disable preemption despite
* having interrupts disabled.
* This serves two purposes: it makes it much less likely that we would
* accidentally schedule in exception context and it will force a warning
* if we somehow manage to schedule by accident.
*/
static void debug_exception_enter(struct pt_regs *regs)
{
/*
* Tell lockdep we disabled irqs in entry.S. Do nothing if they were
* already disabled to preserve the last enabled/disabled addresses.
*/
if (interrupts_enabled(regs))
trace_hardirqs_off();
if (user_mode(regs)) {
RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
} else {
/* * We might have interrupted pretty much anything. In
* fact, if we're a debug exception, we can even interrupt
* NMI processing. We don't want this code makes in_nmi()
* to return true, but we need to notify RCU.
*/
rcu_nmi_enter();
}
preempt_disable();
/* This code is a bit fragile. Test it. */
RCU_LOCKDEP_WARN(!rcu_is_watching(), "exception_enter didn't work");
}
NOKPROBE_SYMBOL(debug_exception_enter);
static void debug_exception_exit(struct pt_regs *regs)
{
preempt_enable_no_resched();
if (!user_mode(regs))
rcu_nmi_exit();
if (interrupts_enabled(regs))
trace_hardirqs_on();
}
NOKPROBE_SYMBOL(debug_exception_exit);
#ifdef CONFIG_ARM64_ERRATUM_1463225
DECLARE_PER_CPU(int, __in_cortex_a76_erratum_1463225_wa);
static int __exception
cortex_a76_erratum_1463225_debug_handler(struct pt_regs *regs)
{
if (user_mode(regs))
return 0;
if (!__this_cpu_read(__in_cortex_a76_erratum_1463225_wa))
return 0;
/*
* We've taken a dummy step exception from the kernel to ensure
* that interrupts are re-enabled on the syscall path. Return back
* to cortex_a76_erratum_1463225_svc_handler() with debug exceptions
* masked so that we can safely restore the mdscr and get on with
* handling the syscall.
*/
regs->pstate |= PSR_D_BIT;
return 1;
}
#else
static int __exception
cortex_a76_erratum_1463225_debug_handler(struct pt_regs *regs)
{
return 0;
}
#endif /* CONFIG_ARM64_ERRATUM_1463225 */
asmlinkage void __exception do_debug_exception(unsigned long addr_if_watchpoint,
unsigned int esr,
struct pt_regs *regs)
{
const struct fault_info *inf = esr_to_debug_fault_info(esr);
unsigned long pc = instruction_pointer(regs);
if (cortex_a76_erratum_1463225_debug_handler(regs))
return;
debug_exception_enter(regs);
if (user_mode(regs) && !is_ttbr0_addr(pc)) arm64_apply_bp_hardening();
if (inf->fn(addr_if_watchpoint, esr, regs)) {
arm64_notify_die(inf->name, regs,
inf->sig, inf->code, (void __user *)pc, esr);
}
debug_exception_exit(regs);
}
NOKPROBE_SYMBOL(do_debug_exception);