From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- arch/arm/mm/fault.c | 607 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 607 insertions(+) create mode 100644 arch/arm/mm/fault.c (limited to 'arch/arm/mm/fault.c') diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c new file mode 100644 index 000000000..b0db85310 --- /dev/null +++ b/arch/arm/mm/fault.c @@ -0,0 +1,607 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * linux/arch/arm/mm/fault.c + * + * Copyright (C) 1995 Linus Torvalds + * Modifications for ARM processor (c) 1995-2004 Russell King + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include + +#include "fault.h" + +#ifdef CONFIG_MMU + +/* + * This is useful to dump out the page tables associated with + * 'addr' in mm 'mm'. + */ +void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr) +{ + pgd_t *pgd; + + if (!mm) + mm = &init_mm; + + pgd = pgd_offset(mm, addr); + printk("%s[%08lx] *pgd=%08llx", lvl, addr, (long long)pgd_val(*pgd)); + + do { + p4d_t *p4d; + pud_t *pud; + pmd_t *pmd; + pte_t *pte; + + p4d = p4d_offset(pgd, addr); + if (p4d_none(*p4d)) + break; + + if (p4d_bad(*p4d)) { + pr_cont("(bad)"); + break; + } + + pud = pud_offset(p4d, addr); + if (PTRS_PER_PUD != 1) + pr_cont(", *pud=%08llx", (long long)pud_val(*pud)); + + if (pud_none(*pud)) + break; + + if (pud_bad(*pud)) { + pr_cont("(bad)"); + break; + } + + pmd = pmd_offset(pud, addr); + if (PTRS_PER_PMD != 1) + pr_cont(", *pmd=%08llx", (long long)pmd_val(*pmd)); + + if (pmd_none(*pmd)) + break; + + if (pmd_bad(*pmd)) { + pr_cont("(bad)"); + break; + } + + /* We must not map this if we have highmem enabled */ + if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT))) + break; + + pte = pte_offset_map(pmd, addr); + pr_cont(", *pte=%08llx", (long long)pte_val(*pte)); +#ifndef CONFIG_ARM_LPAE + pr_cont(", *ppte=%08llx", + (long long)pte_val(pte[PTE_HWTABLE_PTRS])); +#endif + pte_unmap(pte); + } while(0); + + pr_cont("\n"); +} +#else /* CONFIG_MMU */ +void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr) +{ } +#endif /* CONFIG_MMU */ + +static inline bool is_write_fault(unsigned int fsr) +{ + return (fsr & FSR_WRITE) && !(fsr & FSR_CM); +} + +static inline bool is_translation_fault(unsigned int fsr) +{ + int fs = fsr_fs(fsr); +#ifdef CONFIG_ARM_LPAE + if ((fs & FS_MMU_NOLL_MASK) == FS_TRANS_NOLL) + return true; +#else + if (fs == FS_L1_TRANS || fs == FS_L2_TRANS) + return true; +#endif + return false; +} + +static void die_kernel_fault(const char *msg, struct mm_struct *mm, + unsigned long addr, unsigned int fsr, + struct pt_regs *regs) +{ + bust_spinlocks(1); + pr_alert("8<--- cut here ---\n"); + pr_alert("Unable to handle kernel %s at virtual address %08lx\n", + msg, addr); + + show_pte(KERN_ALERT, mm, addr); + die("Oops", regs, fsr); + bust_spinlocks(0); + make_task_dead(SIGKILL); +} + +/* + * Oops. The kernel tried to access some page that wasn't present. + */ +static void +__do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr, + struct pt_regs *regs) +{ + const char *msg; + /* + * Are we prepared to handle this kernel fault? + */ + if (fixup_exception(regs)) + return; + + /* + * No handler, we'll have to terminate things with extreme prejudice. + */ + if (addr < PAGE_SIZE) { + msg = "NULL pointer dereference"; + } else { + if (is_translation_fault(fsr) && + kfence_handle_page_fault(addr, is_write_fault(fsr), regs)) + return; + + msg = "paging request"; + } + + die_kernel_fault(msg, mm, addr, fsr, regs); +} + +/* + * Something tried to access memory that isn't in our memory map.. + * User mode accesses just cause a SIGSEGV + */ +static void +__do_user_fault(unsigned long addr, unsigned int fsr, unsigned int sig, + int code, struct pt_regs *regs) +{ + struct task_struct *tsk = current; + + if (addr > TASK_SIZE) + harden_branch_predictor(); + +#ifdef CONFIG_DEBUG_USER + if (((user_debug & UDBG_SEGV) && (sig == SIGSEGV)) || + ((user_debug & UDBG_BUS) && (sig == SIGBUS))) { + pr_err("8<--- cut here ---\n"); + pr_err("%s: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n", + tsk->comm, sig, addr, fsr); + show_pte(KERN_ERR, tsk->mm, addr); + show_regs(regs); + } +#endif +#ifndef CONFIG_KUSER_HELPERS + if ((sig == SIGSEGV) && ((addr & PAGE_MASK) == 0xffff0000)) + printk_ratelimited(KERN_DEBUG + "%s: CONFIG_KUSER_HELPERS disabled at 0x%08lx\n", + tsk->comm, addr); +#endif + + tsk->thread.address = addr; + tsk->thread.error_code = fsr; + tsk->thread.trap_no = 14; + force_sig_fault(sig, code, (void __user *)addr); +} + +void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs) +{ + struct task_struct *tsk = current; + struct mm_struct *mm = tsk->active_mm; + + /* + * If we are in kernel mode at this point, we + * have no context to handle this fault with. + */ + if (user_mode(regs)) + __do_user_fault(addr, fsr, SIGSEGV, SEGV_MAPERR, regs); + else + __do_kernel_fault(mm, addr, fsr, regs); +} + +#ifdef CONFIG_MMU +#define VM_FAULT_BADMAP ((__force vm_fault_t)0x010000) +#define VM_FAULT_BADACCESS ((__force vm_fault_t)0x020000) + +static inline bool is_permission_fault(unsigned int fsr) +{ + int fs = fsr_fs(fsr); +#ifdef CONFIG_ARM_LPAE + if ((fs & FS_MMU_NOLL_MASK) == FS_PERM_NOLL) + return true; +#else + if (fs == FS_L1_PERM || fs == FS_L2_PERM) + return true; +#endif + return false; +} + +static int __kprobes +do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) +{ + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma; + int sig, code; + vm_fault_t fault; + unsigned int flags = FAULT_FLAG_DEFAULT; + unsigned long vm_flags = VM_ACCESS_FLAGS; + + if (kprobe_page_fault(regs, fsr)) + return 0; + + + /* Enable interrupts if they were enabled in the parent context. */ + if (interrupts_enabled(regs)) + local_irq_enable(); + + /* + * 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)) + flags |= FAULT_FLAG_USER; + + if (is_write_fault(fsr)) { + flags |= FAULT_FLAG_WRITE; + vm_flags = VM_WRITE; + } + + if (fsr & FSR_LNX_PF) { + vm_flags = VM_EXEC; + + if (is_permission_fault(fsr) && !user_mode(regs)) + die_kernel_fault("execution of memory", + mm, addr, fsr, regs); + } + + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr); + +retry: + vma = lock_mm_and_find_vma(mm, addr, regs); + if (unlikely(!vma)) { + fault = VM_FAULT_BADMAP; + goto bad_area; + } + + /* + * ok, we have a good vm_area for this memory access, check the + * permissions on the VMA allow for the fault which occurred. + */ + if (!(vma->vm_flags & vm_flags)) + fault = VM_FAULT_BADACCESS; + else + fault = handle_mm_fault(vma, addr & PAGE_MASK, flags, regs); + + /* If we need to retry but a fatal signal is pending, handle the + * signal first. We do not need to release the mmap_lock because + * it would already be released in __lock_page_or_retry in + * mm/filemap.c. */ + if (fault_signal_pending(fault, regs)) { + if (!user_mode(regs)) + goto no_context; + return 0; + } + + /* The fault is fully completed (including releasing mmap lock) */ + if (fault & VM_FAULT_COMPLETED) + return 0; + + if (!(fault & VM_FAULT_ERROR)) { + if (fault & VM_FAULT_RETRY) { + flags |= FAULT_FLAG_TRIED; + goto retry; + } + } + + mmap_read_unlock(mm); + + /* + * Handle the "normal" case first - VM_FAULT_MAJOR + */ + if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS)))) + return 0; + +bad_area: + /* + * 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; + } + + if (fault & VM_FAULT_SIGBUS) { + /* + * We had some memory, but were unable to + * successfully fix up this page fault. + */ + sig = SIGBUS; + code = BUS_ADRERR; + } else { + /* + * Something tried to access memory that + * isn't in our memory map.. + */ + sig = SIGSEGV; + code = fault == VM_FAULT_BADACCESS ? + SEGV_ACCERR : SEGV_MAPERR; + } + + __do_user_fault(addr, fsr, sig, code, regs); + return 0; + +no_context: + __do_kernel_fault(mm, addr, fsr, regs); + return 0; +} +#else /* CONFIG_MMU */ +static int +do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) +{ + return 0; +} +#endif /* CONFIG_MMU */ + +/* + * First Level Translation Fault Handler + * + * We enter here because the first level page table doesn't contain + * a valid entry for the address. + * + * If the address is in kernel space (>= TASK_SIZE), then we are + * probably faulting in the vmalloc() area. + * + * If the init_task's first level page tables contains the relevant + * entry, we copy the it to this task. If not, we send the process + * a signal, fixup the exception, or oops the kernel. + * + * NOTE! We MUST NOT take any locks for this case. We may be in an + * interrupt or a critical region, and should only copy the information + * from the master page table, nothing more. + */ +#ifdef CONFIG_MMU +static int __kprobes +do_translation_fault(unsigned long addr, unsigned int fsr, + struct pt_regs *regs) +{ + unsigned int index; + pgd_t *pgd, *pgd_k; + p4d_t *p4d, *p4d_k; + pud_t *pud, *pud_k; + pmd_t *pmd, *pmd_k; + + if (addr < TASK_SIZE) + return do_page_fault(addr, fsr, regs); + + if (user_mode(regs)) + goto bad_area; + + index = pgd_index(addr); + + pgd = cpu_get_pgd() + index; + pgd_k = init_mm.pgd + index; + + p4d = p4d_offset(pgd, addr); + p4d_k = p4d_offset(pgd_k, addr); + + if (p4d_none(*p4d_k)) + goto bad_area; + if (!p4d_present(*p4d)) + set_p4d(p4d, *p4d_k); + + pud = pud_offset(p4d, addr); + pud_k = pud_offset(p4d_k, addr); + + if (pud_none(*pud_k)) + goto bad_area; + if (!pud_present(*pud)) + set_pud(pud, *pud_k); + + pmd = pmd_offset(pud, addr); + pmd_k = pmd_offset(pud_k, addr); + +#ifdef CONFIG_ARM_LPAE + /* + * Only one hardware entry per PMD with LPAE. + */ + index = 0; +#else + /* + * On ARM one Linux PGD entry contains two hardware entries (see page + * tables layout in pgtable.h). We normally guarantee that we always + * fill both L1 entries. But create_mapping() doesn't follow the rule. + * It can create inidividual L1 entries, so here we have to call + * pmd_none() check for the entry really corresponded to address, not + * for the first of pair. + */ + index = (addr >> SECTION_SHIFT) & 1; +#endif + if (pmd_none(pmd_k[index])) + goto bad_area; + + copy_pmd(pmd, pmd_k); + return 0; + +bad_area: + do_bad_area(addr, fsr, regs); + return 0; +} +#else /* CONFIG_MMU */ +static int +do_translation_fault(unsigned long addr, unsigned int fsr, + struct pt_regs *regs) +{ + return 0; +} +#endif /* CONFIG_MMU */ + +/* + * Some section permission faults need to be handled gracefully. + * They can happen due to a __{get,put}_user during an oops. + */ +#ifndef CONFIG_ARM_LPAE +static int +do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) +{ + do_bad_area(addr, fsr, regs); + return 0; +} +#endif /* CONFIG_ARM_LPAE */ + +/* + * This abort handler always returns "fault". + */ +static int +do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs) +{ + return 1; +} + +struct fsr_info { + int (*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs); + int sig; + int code; + const char *name; +}; + +/* FSR definition */ +#ifdef CONFIG_ARM_LPAE +#include "fsr-3level.c" +#else +#include "fsr-2level.c" +#endif + +void __init +hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *), + int sig, int code, const char *name) +{ + if (nr < 0 || nr >= ARRAY_SIZE(fsr_info)) + BUG(); + + fsr_info[nr].fn = fn; + fsr_info[nr].sig = sig; + fsr_info[nr].code = code; + fsr_info[nr].name = name; +} + +/* + * Dispatch a data abort to the relevant handler. + */ +asmlinkage void +do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs) +{ + const struct fsr_info *inf = fsr_info + fsr_fs(fsr); + + if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs)) + return; + + pr_alert("8<--- cut here ---\n"); + pr_alert("Unhandled fault: %s (0x%03x) at 0x%08lx\n", + inf->name, fsr, addr); + show_pte(KERN_ALERT, current->mm, addr); + + arm_notify_die("", regs, inf->sig, inf->code, (void __user *)addr, + fsr, 0); +} + +void __init +hook_ifault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *), + int sig, int code, const char *name) +{ + if (nr < 0 || nr >= ARRAY_SIZE(ifsr_info)) + BUG(); + + ifsr_info[nr].fn = fn; + ifsr_info[nr].sig = sig; + ifsr_info[nr].code = code; + ifsr_info[nr].name = name; +} + +asmlinkage void +do_PrefetchAbort(unsigned long addr, unsigned int ifsr, struct pt_regs *regs) +{ + const struct fsr_info *inf = ifsr_info + fsr_fs(ifsr); + + if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs)) + return; + + pr_alert("Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n", + inf->name, ifsr, addr); + + arm_notify_die("", regs, inf->sig, inf->code, (void __user *)addr, + ifsr, 0); +} + +/* + * Abort handler to be used only during first unmasking of asynchronous aborts + * on the boot CPU. This makes sure that the machine will not die if the + * firmware/bootloader left an imprecise abort pending for us to trip over. + */ +static int __init early_abort_handler(unsigned long addr, unsigned int fsr, + struct pt_regs *regs) +{ + pr_warn("Hit pending asynchronous external abort (FSR=0x%08x) during " + "first unmask, this is most likely caused by a " + "firmware/bootloader bug.\n", fsr); + + return 0; +} + +void __init early_abt_enable(void) +{ + fsr_info[FSR_FS_AEA].fn = early_abort_handler; + local_abt_enable(); + fsr_info[FSR_FS_AEA].fn = do_bad; +} + +#ifndef CONFIG_ARM_LPAE +static int __init exceptions_init(void) +{ + if (cpu_architecture() >= CPU_ARCH_ARMv6) { + hook_fault_code(4, do_translation_fault, SIGSEGV, SEGV_MAPERR, + "I-cache maintenance fault"); + } + + if (cpu_architecture() >= CPU_ARCH_ARMv7) { + /* + * TODO: Access flag faults introduced in ARMv6K. + * Runtime check for 'K' extension is needed + */ + hook_fault_code(3, do_bad, SIGSEGV, SEGV_MAPERR, + "section access flag fault"); + hook_fault_code(6, do_bad, SIGSEGV, SEGV_MAPERR, + "section access flag fault"); + } + + return 0; +} + +arch_initcall(exceptions_init); +#endif -- cgit v1.2.3