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![Anshuman Khandual](/assets/img/avatar_default.png)
Architectures which support kprobes have very similar boilerplate around
calling kprobe_fault_handler(). Use a helper function in kprobes.h to
unify them, based on the x86 code.
This changes the behaviour for other architectures when preemption is
enabled. Previously, they would have disabled preemption while calling
the kprobe handler. However, preemption would be disabled if this fault
was due to a kprobe, so we know the fault was not due to a kprobe
handler and can simply return failure.
This behaviour was introduced in commit a980c0ef9f
("x86/kprobes:
Refactor kprobes_fault() like kprobe_exceptions_notify()")
[anshuman.khandual@arm.com: export kprobe_fault_handler()]
Link: http://lkml.kernel.org/r/1561133358-8876-1-git-send-email-anshuman.khandual@arm.com
Link: http://lkml.kernel.org/r/1560420444-25737-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
497 lines
11 KiB
C
497 lines
11 KiB
C
/*
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* Page fault handler for SH with an MMU.
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*
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* Copyright (C) 1999 Niibe Yutaka
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* Copyright (C) 2003 - 2012 Paul Mundt
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*
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* Based on linux/arch/i386/mm/fault.c:
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* Copyright (C) 1995 Linus Torvalds
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*/
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/sched/signal.h>
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#include <linux/hardirq.h>
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#include <linux/kprobes.h>
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#include <linux/perf_event.h>
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#include <linux/kdebug.h>
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#include <linux/uaccess.h>
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#include <asm/io_trapped.h>
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#include <asm/mmu_context.h>
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#include <asm/tlbflush.h>
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#include <asm/traps.h>
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static void
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force_sig_info_fault(int si_signo, int si_code, unsigned long address)
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{
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force_sig_fault(si_signo, si_code, (void __user *)address);
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}
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/*
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* This is useful to dump out the page tables associated with
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* 'addr' in mm 'mm'.
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*/
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static void show_pte(struct mm_struct *mm, unsigned long addr)
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{
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pgd_t *pgd;
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if (mm) {
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pgd = mm->pgd;
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} else {
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pgd = get_TTB();
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if (unlikely(!pgd))
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pgd = swapper_pg_dir;
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}
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printk(KERN_ALERT "pgd = %p\n", pgd);
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pgd += pgd_index(addr);
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printk(KERN_ALERT "[%08lx] *pgd=%0*Lx", addr,
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(u32)(sizeof(*pgd) * 2), (u64)pgd_val(*pgd));
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do {
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pud_t *pud;
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pmd_t *pmd;
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pte_t *pte;
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if (pgd_none(*pgd))
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break;
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if (pgd_bad(*pgd)) {
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printk("(bad)");
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break;
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}
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pud = pud_offset(pgd, addr);
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if (PTRS_PER_PUD != 1)
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printk(", *pud=%0*Lx", (u32)(sizeof(*pud) * 2),
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(u64)pud_val(*pud));
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if (pud_none(*pud))
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break;
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if (pud_bad(*pud)) {
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printk("(bad)");
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break;
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}
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pmd = pmd_offset(pud, addr);
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if (PTRS_PER_PMD != 1)
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printk(", *pmd=%0*Lx", (u32)(sizeof(*pmd) * 2),
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(u64)pmd_val(*pmd));
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if (pmd_none(*pmd))
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break;
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if (pmd_bad(*pmd)) {
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printk("(bad)");
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break;
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}
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/* We must not map this if we have highmem enabled */
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if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT)))
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break;
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pte = pte_offset_kernel(pmd, addr);
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printk(", *pte=%0*Lx", (u32)(sizeof(*pte) * 2),
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(u64)pte_val(*pte));
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} while (0);
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printk("\n");
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}
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static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
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{
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unsigned index = pgd_index(address);
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pgd_t *pgd_k;
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pud_t *pud, *pud_k;
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pmd_t *pmd, *pmd_k;
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pgd += index;
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pgd_k = init_mm.pgd + index;
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if (!pgd_present(*pgd_k))
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return NULL;
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pud = pud_offset(pgd, address);
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pud_k = pud_offset(pgd_k, address);
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if (!pud_present(*pud_k))
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return NULL;
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if (!pud_present(*pud))
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set_pud(pud, *pud_k);
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pmd = pmd_offset(pud, address);
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pmd_k = pmd_offset(pud_k, address);
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if (!pmd_present(*pmd_k))
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return NULL;
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if (!pmd_present(*pmd))
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set_pmd(pmd, *pmd_k);
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else {
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/*
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* The page tables are fully synchronised so there must
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* be another reason for the fault. Return NULL here to
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* signal that we have not taken care of the fault.
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*/
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BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k));
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return NULL;
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}
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return pmd_k;
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}
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#ifdef CONFIG_SH_STORE_QUEUES
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#define __FAULT_ADDR_LIMIT P3_ADDR_MAX
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#else
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#define __FAULT_ADDR_LIMIT VMALLOC_END
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#endif
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/*
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* Handle a fault on the vmalloc or module mapping area
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*/
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static noinline int vmalloc_fault(unsigned long address)
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{
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pgd_t *pgd_k;
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pmd_t *pmd_k;
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pte_t *pte_k;
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/* Make sure we are in vmalloc/module/P3 area: */
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if (!(address >= VMALLOC_START && address < __FAULT_ADDR_LIMIT))
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return -1;
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/*
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* Synchronize this task's top level page-table
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* with the 'reference' page table.
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*
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* Do _not_ use "current" here. We might be inside
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* an interrupt in the middle of a task switch..
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*/
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pgd_k = get_TTB();
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pmd_k = vmalloc_sync_one(pgd_k, address);
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if (!pmd_k)
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return -1;
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pte_k = pte_offset_kernel(pmd_k, address);
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if (!pte_present(*pte_k))
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return -1;
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return 0;
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}
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static void
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show_fault_oops(struct pt_regs *regs, unsigned long address)
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{
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if (!oops_may_print())
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return;
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printk(KERN_ALERT "BUG: unable to handle kernel ");
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if (address < PAGE_SIZE)
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printk(KERN_CONT "NULL pointer dereference");
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else
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printk(KERN_CONT "paging request");
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printk(KERN_CONT " at %08lx\n", address);
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printk(KERN_ALERT "PC:");
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printk_address(regs->pc, 1);
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show_pte(NULL, address);
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}
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static noinline void
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no_context(struct pt_regs *regs, unsigned long error_code,
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unsigned long address)
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{
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/* Are we prepared to handle this kernel fault? */
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if (fixup_exception(regs))
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return;
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if (handle_trapped_io(regs, address))
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return;
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/*
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* Oops. The kernel tried to access some bad page. We'll have to
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* terminate things with extreme prejudice.
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*/
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bust_spinlocks(1);
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show_fault_oops(regs, address);
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die("Oops", regs, error_code);
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bust_spinlocks(0);
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do_exit(SIGKILL);
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}
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static void
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__bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
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unsigned long address, int si_code)
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{
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/* User mode accesses just cause a SIGSEGV */
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if (user_mode(regs)) {
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/*
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* It's possible to have interrupts off here:
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*/
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local_irq_enable();
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force_sig_info_fault(SIGSEGV, si_code, address);
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return;
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}
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no_context(regs, error_code, address);
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}
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static noinline void
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bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
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unsigned long address)
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{
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__bad_area_nosemaphore(regs, error_code, address, SEGV_MAPERR);
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}
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static void
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__bad_area(struct pt_regs *regs, unsigned long error_code,
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unsigned long address, int si_code)
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{
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struct mm_struct *mm = current->mm;
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/*
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* Something tried to access memory that isn't in our memory map..
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* Fix it, but check if it's kernel or user first..
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*/
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up_read(&mm->mmap_sem);
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__bad_area_nosemaphore(regs, error_code, address, si_code);
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}
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static noinline void
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bad_area(struct pt_regs *regs, unsigned long error_code, unsigned long address)
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{
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__bad_area(regs, error_code, address, SEGV_MAPERR);
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}
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static noinline void
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bad_area_access_error(struct pt_regs *regs, unsigned long error_code,
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unsigned long address)
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{
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__bad_area(regs, error_code, address, SEGV_ACCERR);
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}
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static void
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do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address)
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{
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struct task_struct *tsk = current;
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struct mm_struct *mm = tsk->mm;
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up_read(&mm->mmap_sem);
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/* Kernel mode? Handle exceptions or die: */
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if (!user_mode(regs))
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no_context(regs, error_code, address);
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force_sig_info_fault(SIGBUS, BUS_ADRERR, address);
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}
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static noinline int
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mm_fault_error(struct pt_regs *regs, unsigned long error_code,
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unsigned long address, vm_fault_t fault)
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{
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/*
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* Pagefault was interrupted by SIGKILL. We have no reason to
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* continue pagefault.
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*/
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if (fatal_signal_pending(current)) {
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if (!(fault & VM_FAULT_RETRY))
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up_read(¤t->mm->mmap_sem);
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if (!user_mode(regs))
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no_context(regs, error_code, address);
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return 1;
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}
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if (!(fault & VM_FAULT_ERROR))
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return 0;
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if (fault & VM_FAULT_OOM) {
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/* Kernel mode? Handle exceptions or die: */
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if (!user_mode(regs)) {
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up_read(¤t->mm->mmap_sem);
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no_context(regs, error_code, address);
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return 1;
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}
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up_read(¤t->mm->mmap_sem);
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/*
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* We ran out of memory, call the OOM killer, and return the
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* userspace (which will retry the fault, or kill us if we got
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* oom-killed):
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*/
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pagefault_out_of_memory();
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} else {
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if (fault & VM_FAULT_SIGBUS)
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do_sigbus(regs, error_code, address);
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else if (fault & VM_FAULT_SIGSEGV)
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bad_area(regs, error_code, address);
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else
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BUG();
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}
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return 1;
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}
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static inline int access_error(int error_code, struct vm_area_struct *vma)
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{
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if (error_code & FAULT_CODE_WRITE) {
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/* write, present and write, not present: */
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if (unlikely(!(vma->vm_flags & VM_WRITE)))
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return 1;
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return 0;
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}
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/* ITLB miss on NX page */
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if (unlikely((error_code & FAULT_CODE_ITLB) &&
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!(vma->vm_flags & VM_EXEC)))
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return 1;
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/* read, not present: */
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if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))))
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return 1;
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return 0;
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}
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static int fault_in_kernel_space(unsigned long address)
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{
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return address >= TASK_SIZE;
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}
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/*
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* This routine handles page faults. It determines the address,
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* and the problem, and then passes it off to one of the appropriate
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* routines.
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*/
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asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
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unsigned long error_code,
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unsigned long address)
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{
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unsigned long vec;
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struct task_struct *tsk;
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struct mm_struct *mm;
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struct vm_area_struct * vma;
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vm_fault_t fault;
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unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
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tsk = current;
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mm = tsk->mm;
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vec = lookup_exception_vector();
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/*
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* We fault-in kernel-space virtual memory on-demand. The
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* 'reference' page table is init_mm.pgd.
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*
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* NOTE! We MUST NOT take any locks for this case. We may
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* be in an interrupt or a critical region, and should
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* only copy the information from the master page table,
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* nothing more.
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*/
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if (unlikely(fault_in_kernel_space(address))) {
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if (vmalloc_fault(address) >= 0)
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return;
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if (kprobe_page_fault(regs, vec))
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return;
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bad_area_nosemaphore(regs, error_code, address);
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return;
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}
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if (unlikely(kprobe_page_fault(regs, vec)))
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return;
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/* Only enable interrupts if they were on before the fault */
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if ((regs->sr & SR_IMASK) != SR_IMASK)
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local_irq_enable();
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
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/*
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* If we're in an interrupt, have no user context or are running
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* with pagefaults disabled then we must not take the fault:
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*/
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if (unlikely(faulthandler_disabled() || !mm)) {
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bad_area_nosemaphore(regs, error_code, address);
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return;
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}
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retry:
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down_read(&mm->mmap_sem);
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vma = find_vma(mm, address);
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if (unlikely(!vma)) {
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bad_area(regs, error_code, address);
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return;
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}
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if (likely(vma->vm_start <= address))
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goto good_area;
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if (unlikely(!(vma->vm_flags & VM_GROWSDOWN))) {
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bad_area(regs, error_code, address);
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return;
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}
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if (unlikely(expand_stack(vma, address))) {
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bad_area(regs, error_code, address);
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return;
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}
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/*
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* Ok, we have a good vm_area for this memory access, so
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* we can handle it..
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*/
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good_area:
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if (unlikely(access_error(error_code, vma))) {
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bad_area_access_error(regs, error_code, address);
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return;
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}
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set_thread_fault_code(error_code);
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if (user_mode(regs))
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flags |= FAULT_FLAG_USER;
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if (error_code & FAULT_CODE_WRITE)
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flags |= FAULT_FLAG_WRITE;
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/*
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* If for any reason at all we couldn't handle the fault,
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* make sure we exit gracefully rather than endlessly redo
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* the fault.
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*/
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fault = handle_mm_fault(vma, address, flags);
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if (unlikely(fault & (VM_FAULT_RETRY | VM_FAULT_ERROR)))
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if (mm_fault_error(regs, error_code, address, fault))
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return;
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if (flags & FAULT_FLAG_ALLOW_RETRY) {
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if (fault & VM_FAULT_MAJOR) {
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tsk->maj_flt++;
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
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regs, address);
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} else {
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tsk->min_flt++;
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
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regs, address);
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}
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if (fault & VM_FAULT_RETRY) {
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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/*
|
|
* No need to up_read(&mm->mmap_sem) as we would
|
|
* have already released it in __lock_page_or_retry
|
|
* in mm/filemap.c.
|
|
*/
|
|
goto retry;
|
|
}
|
|
}
|
|
|
|
up_read(&mm->mmap_sem);
|
|
}
|