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-rw-r--r--kernel/arch/powerpc/mm/fault.c544
1 files changed, 544 insertions, 0 deletions
diff --git a/kernel/arch/powerpc/mm/fault.c b/kernel/arch/powerpc/mm/fault.c
new file mode 100644
index 000000000..6d535973b
--- /dev/null
+++ b/kernel/arch/powerpc/mm/fault.c
@@ -0,0 +1,544 @@
+/*
+ * PowerPC version
+ * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
+ *
+ * Derived from "arch/i386/mm/fault.c"
+ * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
+ *
+ * Modified by Cort Dougan and Paul Mackerras.
+ *
+ * Modified for PPC64 by Dave Engebretsen (engebret@ibm.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/highmem.h>
+#include <linux/module.h>
+#include <linux/kprobes.h>
+#include <linux/kdebug.h>
+#include <linux/perf_event.h>
+#include <linux/ratelimit.h>
+#include <linux/context_tracking.h>
+#include <linux/hugetlb.h>
+#include <linux/uaccess.h>
+
+#include <asm/firmware.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <asm/mmu.h>
+#include <asm/mmu_context.h>
+#include <asm/tlbflush.h>
+#include <asm/siginfo.h>
+#include <asm/debug.h>
+
+#include "icswx.h"
+
+#ifdef CONFIG_KPROBES
+static inline int notify_page_fault(struct pt_regs *regs)
+{
+ int ret = 0;
+
+ /* kprobe_running() needs smp_processor_id() */
+ if (!user_mode(regs)) {
+ preempt_disable();
+ if (kprobe_running() && kprobe_fault_handler(regs, 11))
+ ret = 1;
+ preempt_enable();
+ }
+
+ return ret;
+}
+#else
+static inline int notify_page_fault(struct pt_regs *regs)
+{
+ return 0;
+}
+#endif
+
+/*
+ * Check whether the instruction at regs->nip is a store using
+ * an update addressing form which will update r1.
+ */
+static int store_updates_sp(struct pt_regs *regs)
+{
+ unsigned int inst;
+
+ if (get_user(inst, (unsigned int __user *)regs->nip))
+ return 0;
+ /* check for 1 in the rA field */
+ if (((inst >> 16) & 0x1f) != 1)
+ return 0;
+ /* check major opcode */
+ switch (inst >> 26) {
+ case 37: /* stwu */
+ case 39: /* stbu */
+ case 45: /* sthu */
+ case 53: /* stfsu */
+ case 55: /* stfdu */
+ return 1;
+ case 62: /* std or stdu */
+ return (inst & 3) == 1;
+ case 31:
+ /* check minor opcode */
+ switch ((inst >> 1) & 0x3ff) {
+ case 181: /* stdux */
+ case 183: /* stwux */
+ case 247: /* stbux */
+ case 439: /* sthux */
+ case 695: /* stfsux */
+ case 759: /* stfdux */
+ return 1;
+ }
+ }
+ return 0;
+}
+/*
+ * do_page_fault error handling helpers
+ */
+
+#define MM_FAULT_RETURN 0
+#define MM_FAULT_CONTINUE -1
+#define MM_FAULT_ERR(sig) (sig)
+
+static int do_sigbus(struct pt_regs *regs, unsigned long address,
+ unsigned int fault)
+{
+ siginfo_t info;
+ unsigned int lsb = 0;
+
+ up_read(&current->mm->mmap_sem);
+
+ if (!user_mode(regs))
+ return MM_FAULT_ERR(SIGBUS);
+
+ current->thread.trap_nr = BUS_ADRERR;
+ info.si_signo = SIGBUS;
+ info.si_errno = 0;
+ info.si_code = BUS_ADRERR;
+ info.si_addr = (void __user *)address;
+#ifdef CONFIG_MEMORY_FAILURE
+ if (fault & (VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE)) {
+ pr_err("MCE: Killing %s:%d due to hardware memory corruption fault at %lx\n",
+ current->comm, current->pid, address);
+ info.si_code = BUS_MCEERR_AR;
+ }
+
+ if (fault & VM_FAULT_HWPOISON_LARGE)
+ lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault));
+ if (fault & VM_FAULT_HWPOISON)
+ lsb = PAGE_SHIFT;
+#endif
+ info.si_addr_lsb = lsb;
+ force_sig_info(SIGBUS, &info, current);
+ return MM_FAULT_RETURN;
+}
+
+static int mm_fault_error(struct pt_regs *regs, unsigned long addr, int fault)
+{
+ /*
+ * Pagefault was interrupted by SIGKILL. We have no reason to
+ * continue the pagefault.
+ */
+ if (fatal_signal_pending(current)) {
+ /*
+ * If we have retry set, the mmap semaphore will have
+ * alrady been released in __lock_page_or_retry(). Else
+ * we release it now.
+ */
+ if (!(fault & VM_FAULT_RETRY))
+ up_read(&current->mm->mmap_sem);
+ /* Coming from kernel, we need to deal with uaccess fixups */
+ if (user_mode(regs))
+ return MM_FAULT_RETURN;
+ return MM_FAULT_ERR(SIGKILL);
+ }
+
+ /* No fault: be happy */
+ if (!(fault & VM_FAULT_ERROR))
+ return MM_FAULT_CONTINUE;
+
+ /* Out of memory */
+ if (fault & VM_FAULT_OOM) {
+ up_read(&current->mm->mmap_sem);
+
+ /*
+ * We ran out of memory, or some other thing happened to us that
+ * made us unable to handle the page fault gracefully.
+ */
+ if (!user_mode(regs))
+ return MM_FAULT_ERR(SIGKILL);
+ pagefault_out_of_memory();
+ return MM_FAULT_RETURN;
+ }
+
+ if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE))
+ return do_sigbus(regs, addr, fault);
+
+ /* We don't understand the fault code, this is fatal */
+ BUG();
+ return MM_FAULT_CONTINUE;
+}
+
+/*
+ * For 600- and 800-family processors, the error_code parameter is DSISR
+ * for a data fault, SRR1 for an instruction fault. For 400-family processors
+ * the error_code parameter is ESR for a data fault, 0 for an instruction
+ * fault.
+ * For 64-bit processors, the error_code parameter is
+ * - DSISR for a non-SLB data access fault,
+ * - SRR1 & 0x08000000 for a non-SLB instruction access fault
+ * - 0 any SLB fault.
+ *
+ * The return value is 0 if the fault was handled, or the signal
+ * number if this is a kernel fault that can't be handled here.
+ */
+int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
+ unsigned long error_code)
+{
+ enum ctx_state prev_state = exception_enter();
+ struct vm_area_struct * vma;
+ struct mm_struct *mm = current->mm;
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
+ int code = SEGV_MAPERR;
+ int is_write = 0;
+ int trap = TRAP(regs);
+ int is_exec = trap == 0x400;
+ int fault;
+ int rc = 0, store_update_sp = 0;
+
+#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
+ /*
+ * Fortunately the bit assignments in SRR1 for an instruction
+ * fault and DSISR for a data fault are mostly the same for the
+ * bits we are interested in. But there are some bits which
+ * indicate errors in DSISR but can validly be set in SRR1.
+ */
+ if (trap == 0x400)
+ error_code &= 0x48200000;
+ else
+ is_write = error_code & DSISR_ISSTORE;
+#else
+ is_write = error_code & ESR_DST;
+#endif /* CONFIG_4xx || CONFIG_BOOKE */
+
+#ifdef CONFIG_PPC_ICSWX
+ /*
+ * we need to do this early because this "data storage
+ * interrupt" does not update the DAR/DEAR so we don't want to
+ * look at it
+ */
+ if (error_code & ICSWX_DSI_UCT) {
+ rc = acop_handle_fault(regs, address, error_code);
+ if (rc)
+ goto bail;
+ }
+#endif /* CONFIG_PPC_ICSWX */
+
+ if (notify_page_fault(regs))
+ goto bail;
+
+ if (unlikely(debugger_fault_handler(regs)))
+ goto bail;
+
+ /* On a kernel SLB miss we can only check for a valid exception entry */
+ if (!user_mode(regs) && (address >= TASK_SIZE)) {
+ rc = SIGSEGV;
+ goto bail;
+ }
+
+#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE) || \
+ defined(CONFIG_PPC_BOOK3S_64))
+ if (error_code & DSISR_DABRMATCH) {
+ /* breakpoint match */
+ do_break(regs, address, error_code);
+ goto bail;
+ }
+#endif
+
+ /* We restore the interrupt state now */
+ if (!arch_irq_disabled_regs(regs))
+ local_irq_enable();
+
+ if (faulthandler_disabled() || mm == NULL) {
+ if (!user_mode(regs)) {
+ rc = SIGSEGV;
+ goto bail;
+ }
+ /* faulthandler_disabled() in user mode is really bad,
+ as is current->mm == NULL. */
+ printk(KERN_EMERG "Page fault in user mode with "
+ "faulthandler_disabled() = %d mm = %p\n",
+ faulthandler_disabled(), mm);
+ printk(KERN_EMERG "NIP = %lx MSR = %lx\n",
+ regs->nip, regs->msr);
+ die("Weird page fault", regs, SIGSEGV);
+ }
+
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
+
+ /*
+ * We want to do this outside mmap_sem, because reading code around nip
+ * can result in fault, which will cause a deadlock when called with
+ * mmap_sem held
+ */
+ if (user_mode(regs))
+ store_update_sp = store_updates_sp(regs);
+
+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
+
+ /* When running in the kernel we expect faults to occur only to
+ * addresses in user space. All other faults represent errors in the
+ * kernel and should generate an OOPS. Unfortunately, in the case of an
+ * erroneous fault occurring in a code path which already holds mmap_sem
+ * we will deadlock attempting to validate the fault against the
+ * address space. Luckily the kernel only validly references user
+ * space from well defined areas of code, which are listed in the
+ * exceptions table.
+ *
+ * As the vast majority of faults will be valid we will only perform
+ * the source reference check when there is a possibility of a deadlock.
+ * Attempt to lock the address space, if we cannot we then validate the
+ * source. If this is invalid we can skip the address space check,
+ * thus avoiding the deadlock.
+ */
+ if (!down_read_trylock(&mm->mmap_sem)) {
+ if (!user_mode(regs) && !search_exception_tables(regs->nip))
+ goto bad_area_nosemaphore;
+
+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();
+ }
+
+ vma = find_vma(mm, address);
+ if (!vma)
+ goto bad_area;
+ if (vma->vm_start <= address)
+ goto good_area;
+ if (!(vma->vm_flags & VM_GROWSDOWN))
+ goto bad_area;
+
+ /*
+ * N.B. The POWER/Open ABI allows programs to access up to
+ * 288 bytes below the stack pointer.
+ * The kernel signal delivery code writes up to about 1.5kB
+ * below the stack pointer (r1) before decrementing it.
+ * The exec code can write slightly over 640kB to the stack
+ * before setting the user r1. Thus we allow the stack to
+ * expand to 1MB without further checks.
+ */
+ if (address + 0x100000 < vma->vm_end) {
+ /* get user regs even if this fault is in kernel mode */
+ struct pt_regs *uregs = current->thread.regs;
+ if (uregs == NULL)
+ goto bad_area;
+
+ /*
+ * A user-mode access to an address a long way below
+ * the stack pointer is only valid if the instruction
+ * is one which would update the stack pointer to the
+ * address accessed if the instruction completed,
+ * i.e. either stwu rs,n(r1) or stwux rs,r1,rb
+ * (or the byte, halfword, float or double forms).
+ *
+ * If we don't check this then any write to the area
+ * between the last mapped region and the stack will
+ * expand the stack rather than segfaulting.
+ */
+ if (address + 2048 < uregs->gpr[1] && !store_update_sp)
+ goto bad_area;
+ }
+ if (expand_stack(vma, address))
+ goto bad_area;
+
+good_area:
+ code = SEGV_ACCERR;
+#if defined(CONFIG_6xx)
+ if (error_code & 0x95700000)
+ /* an error such as lwarx to I/O controller space,
+ address matching DABR, eciwx, etc. */
+ goto bad_area;
+#endif /* CONFIG_6xx */
+#if defined(CONFIG_8xx)
+ /* The MPC8xx seems to always set 0x80000000, which is
+ * "undefined". Of those that can be set, this is the only
+ * one which seems bad.
+ */
+ if (error_code & 0x10000000)
+ /* Guarded storage error. */
+ goto bad_area;
+#endif /* CONFIG_8xx */
+
+ if (is_exec) {
+ /*
+ * Allow execution from readable areas if the MMU does not
+ * provide separate controls over reading and executing.
+ *
+ * Note: That code used to not be enabled for 4xx/BookE.
+ * It is now as I/D cache coherency for these is done at
+ * set_pte_at() time and I see no reason why the test
+ * below wouldn't be valid on those processors. This -may-
+ * break programs compiled with a really old ABI though.
+ */
+ if (!(vma->vm_flags & VM_EXEC) &&
+ (cpu_has_feature(CPU_FTR_NOEXECUTE) ||
+ !(vma->vm_flags & (VM_READ | VM_WRITE))))
+ goto bad_area;
+#ifdef CONFIG_PPC_STD_MMU
+ /*
+ * protfault should only happen due to us
+ * mapping a region readonly temporarily. PROT_NONE
+ * is also covered by the VMA check above.
+ */
+ WARN_ON_ONCE(error_code & DSISR_PROTFAULT);
+#endif /* CONFIG_PPC_STD_MMU */
+ /* a write */
+ } else if (is_write) {
+ if (!(vma->vm_flags & VM_WRITE))
+ goto bad_area;
+ flags |= FAULT_FLAG_WRITE;
+ /* a read */
+ } else {
+ if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
+ goto bad_area;
+ WARN_ON_ONCE(error_code & DSISR_PROTFAULT);
+ }
+
+ /*
+ * If for any reason at all we couldn't handle the fault,
+ * make sure we exit gracefully rather than endlessly redo
+ * the fault.
+ */
+ fault = handle_mm_fault(mm, vma, address, flags);
+ if (unlikely(fault & (VM_FAULT_RETRY|VM_FAULT_ERROR))) {
+ if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
+ rc = mm_fault_error(regs, address, fault);
+ if (rc >= MM_FAULT_RETURN)
+ goto bail;
+ else
+ rc = 0;
+ }
+
+ /*
+ * Major/minor page fault accounting is only done on the
+ * initial attempt. If we go through a retry, it is extremely
+ * likely that the page will be found in page cache at that point.
+ */
+ if (flags & FAULT_FLAG_ALLOW_RETRY) {
+ if (fault & VM_FAULT_MAJOR) {
+ current->maj_flt++;
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
+ regs, address);
+#ifdef CONFIG_PPC_SMLPAR
+ if (firmware_has_feature(FW_FEATURE_CMO)) {
+ u32 page_ins;
+
+ preempt_disable();
+ page_ins = be32_to_cpu(get_lppaca()->page_ins);
+ page_ins += 1 << PAGE_FACTOR;
+ get_lppaca()->page_ins = cpu_to_be32(page_ins);
+ preempt_enable();
+ }
+#endif /* CONFIG_PPC_SMLPAR */
+ } else {
+ current->min_flt++;
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
+ regs, address);
+ }
+ if (fault & VM_FAULT_RETRY) {
+ /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
+ * of starvation. */
+ flags &= ~FAULT_FLAG_ALLOW_RETRY;
+ flags |= FAULT_FLAG_TRIED;
+ goto retry;
+ }
+ }
+
+ up_read(&mm->mmap_sem);
+ goto bail;
+
+bad_area:
+ up_read(&mm->mmap_sem);
+
+bad_area_nosemaphore:
+ /* User mode accesses cause a SIGSEGV */
+ if (user_mode(regs)) {
+ _exception(SIGSEGV, regs, code, address);
+ goto bail;
+ }
+
+ if (is_exec && (error_code & DSISR_PROTFAULT))
+ printk_ratelimited(KERN_CRIT "kernel tried to execute NX-protected"
+ " page (%lx) - exploit attempt? (uid: %d)\n",
+ address, from_kuid(&init_user_ns, current_uid()));
+
+ rc = SIGSEGV;
+
+bail:
+ exception_exit(prev_state);
+ return rc;
+
+}
+
+/*
+ * bad_page_fault is called when we have a bad access from the kernel.
+ * It is called from the DSI and ISI handlers in head.S and from some
+ * of the procedures in traps.c.
+ */
+void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)
+{
+ const struct exception_table_entry *entry;
+
+ /* Are we prepared to handle this fault? */
+ if ((entry = search_exception_tables(regs->nip)) != NULL) {
+ regs->nip = entry->fixup;
+ return;
+ }
+
+ /* kernel has accessed a bad area */
+
+ switch (regs->trap) {
+ case 0x300:
+ case 0x380:
+ printk(KERN_ALERT "Unable to handle kernel paging request for "
+ "data at address 0x%08lx\n", regs->dar);
+ break;
+ case 0x400:
+ case 0x480:
+ printk(KERN_ALERT "Unable to handle kernel paging request for "
+ "instruction fetch\n");
+ break;
+ default:
+ printk(KERN_ALERT "Unable to handle kernel paging request for "
+ "unknown fault\n");
+ break;
+ }
+ printk(KERN_ALERT "Faulting instruction address: 0x%08lx\n",
+ regs->nip);
+
+ if (task_stack_end_corrupted(current))
+ printk(KERN_ALERT "Thread overran stack, or stack corrupted\n");
+
+ die("Kernel access of bad area", regs, sig);
+}