x86, mm: fault.c cleanup
Impact: cleanup, no code changed Clean up various small details, which can be correctness checked automatically: - tidy up the include file section - eliminate unnecessary includes - introduce show_signal_msg() to clean up code flow - standardize the code flow - standardize comments and other style details - more cleanups, pointed out by checkpatch No code changed on either 32-bit nor 64-bit: arch/x86/mm/fault.o: text data bss dec hex filename 4632 32 24 4688 1250 fault.o.before 4632 32 24 4688 1250 fault.o.after the md5 changed due to a change in a single instruction: 2e8a8241e7f0d69706776a5a26c90bc0 fault.o.before.asm c5c3d36e725586eb74f0e10692f0193e fault.o.after.asm Because a __LINE__ reference in a WARN_ONCE() has changed. On 32-bit a few stack offsets changed - no code size difference nor any functionality difference. Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar
parent
c9e1585b1b
commit
2d4a71676f
@ -1,56 +1,59 @@
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/*
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* Copyright (C) 1995 Linus Torvalds
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* Copyright (C) 2001,2002 Andi Kleen, SuSE Labs.
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* Copyright (C) 2001, 2002 Andi Kleen, SuSE Labs.
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*/
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#include <linux/signal.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/ptrace.h>
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#include <linux/mmiotrace.h>
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#include <linux/mman.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/interrupt.h>
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#include <linux/init.h>
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#include <linux/tty.h>
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#include <linux/vt_kern.h> /* For unblank_screen() */
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#include <linux/mmiotrace.h>
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#include <linux/bootmem.h>
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#include <linux/compiler.h>
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#include <linux/highmem.h>
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#include <linux/bootmem.h> /* for max_low_pfn */
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#include <linux/vmalloc.h>
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#include <linux/module.h>
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#include <linux/kprobes.h>
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#include <linux/uaccess.h>
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#include <linux/vmalloc.h>
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#include <linux/vt_kern.h>
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#include <linux/signal.h>
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#include <linux/kernel.h>
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#include <linux/ptrace.h>
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#include <linux/string.h>
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#include <linux/module.h>
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#include <linux/kdebug.h>
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#include <linux/errno.h>
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#include <linux/magic.h>
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#include <linux/sched.h>
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#include <linux/types.h>
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#include <linux/init.h>
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#include <linux/mman.h>
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#include <linux/tty.h>
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#include <linux/smp.h>
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#include <linux/mm.h>
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#include <asm/system.h>
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#include <asm/desc.h>
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#include <asm/segment.h>
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#include <asm/pgalloc.h>
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#include <asm/smp.h>
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#include <asm/tlbflush.h>
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#include <asm/proto.h>
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#include <asm-generic/sections.h>
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#include <asm/tlbflush.h>
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#include <asm/pgalloc.h>
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#include <asm/segment.h>
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#include <asm/system.h>
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#include <asm/proto.h>
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#include <asm/traps.h>
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#include <asm/desc.h>
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/*
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* Page fault error code bits
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* bit 0 == 0 means no page found, 1 means protection fault
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* bit 1 == 0 means read, 1 means write
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* bit 2 == 0 means kernel, 1 means user-mode
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* bit 3 == 1 means use of reserved bit detected
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* bit 4 == 1 means fault was an instruction fetch
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* Page fault error code bits:
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*
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* bit 0 == 0: no page found 1: protection fault
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* bit 1 == 0: read access 1: write access
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* bit 2 == 0: kernel-mode access 1: user-mode access
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* bit 3 == 1: use of reserved bit detected
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* bit 4 == 1: fault was an instruction fetch
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*/
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#define PF_PROT (1<<0)
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#define PF_WRITE (1<<1)
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#define PF_USER (1<<2)
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#define PF_RSVD (1<<3)
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#define PF_INSTR (1<<4)
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enum x86_pf_error_code {
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PF_PROT = 1 << 0,
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PF_WRITE = 1 << 1,
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PF_USER = 1 << 2,
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PF_RSVD = 1 << 3,
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PF_INSTR = 1 << 4,
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};
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static inline int kmmio_fault(struct pt_regs *regs, unsigned long addr)
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{
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@ -82,23 +85,27 @@ static inline int notify_page_fault(struct pt_regs *regs)
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}
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/*
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* X86_32
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* Prefetch quirks:
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*
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* 32-bit mode:
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*
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* Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch.
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* Check that here and ignore it.
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*
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* X86_64
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* 64-bit mode:
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*
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* Sometimes the CPU reports invalid exceptions on prefetch.
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* Check that here and ignore it.
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*
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* Opcode checker based on code by Richard Brunner
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* Opcode checker based on code by Richard Brunner.
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*/
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static int is_prefetch(struct pt_regs *regs, unsigned long error_code,
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unsigned long addr)
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static int
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is_prefetch(struct pt_regs *regs, unsigned long error_code, unsigned long addr)
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{
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unsigned char *max_instr;
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unsigned char *instr;
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int scan_more = 1;
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int prefetch = 0;
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unsigned char *max_instr;
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/*
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* If it was a exec (instruction fetch) fault on NX page, then
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@ -114,9 +121,9 @@ static int is_prefetch(struct pt_regs *regs, unsigned long error_code,
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return 0;
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while (scan_more && instr < max_instr) {
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unsigned char opcode;
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unsigned char instr_hi;
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unsigned char instr_lo;
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unsigned char opcode;
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if (probe_kernel_address(instr, opcode))
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break;
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@ -173,8 +180,9 @@ static int is_prefetch(struct pt_regs *regs, unsigned long error_code,
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return prefetch;
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}
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static void force_sig_info_fault(int si_signo, int si_code,
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unsigned long address, struct task_struct *tsk)
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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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struct task_struct *tsk)
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{
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siginfo_t info;
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@ -182,6 +190,7 @@ static void force_sig_info_fault(int si_signo, int si_code,
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info.si_errno = 0;
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info.si_code = si_code;
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info.si_addr = (void __user *)address;
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force_sig_info(si_signo, &info, tsk);
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}
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@ -189,6 +198,7 @@ static void force_sig_info_fault(int si_signo, int si_code,
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static int bad_address(void *p)
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{
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unsigned long dummy;
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return probe_kernel_address((unsigned long *)p, dummy);
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}
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#endif
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@ -200,6 +210,7 @@ static void dump_pagetable(unsigned long address)
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page = read_cr3();
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page = ((__typeof__(page) *) __va(page))[address >> PGDIR_SHIFT];
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#ifdef CONFIG_X86_PAE
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printk("*pdpt = %016Lx ", page);
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if ((page >> PAGE_SHIFT) < max_low_pfn
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@ -218,11 +229,12 @@ static void dump_pagetable(unsigned long address)
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* We must not directly access the pte in the highpte
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* case if the page table is located in highmem.
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* And let's rather not kmap-atomic the pte, just in case
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* it's allocated already.
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* it's allocated already:
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*/
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if ((page >> PAGE_SHIFT) < max_low_pfn
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&& (page & _PAGE_PRESENT)
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&& !(page & _PAGE_PSE)) {
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page &= PAGE_MASK;
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page = ((__typeof__(page) *) __va(page))[(address >> PAGE_SHIFT)
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& (PTRS_PER_PTE - 1)];
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@ -239,26 +251,38 @@ static void dump_pagetable(unsigned long address)
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pgd = (pgd_t *)read_cr3();
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pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK);
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pgd += pgd_index(address);
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if (bad_address(pgd)) goto bad;
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if (bad_address(pgd))
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goto bad;
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printk("PGD %lx ", pgd_val(*pgd));
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if (!pgd_present(*pgd)) goto ret;
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if (!pgd_present(*pgd))
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goto out;
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pud = pud_offset(pgd, address);
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if (bad_address(pud)) goto bad;
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if (bad_address(pud))
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goto bad;
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printk("PUD %lx ", pud_val(*pud));
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if (!pud_present(*pud) || pud_large(*pud))
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goto ret;
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goto out;
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pmd = pmd_offset(pud, address);
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if (bad_address(pmd)) goto bad;
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if (bad_address(pmd))
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goto bad;
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printk("PMD %lx ", pmd_val(*pmd));
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if (!pmd_present(*pmd) || pmd_large(*pmd)) goto ret;
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if (!pmd_present(*pmd) || pmd_large(*pmd))
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goto out;
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pte = pte_offset_kernel(pmd, address);
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if (bad_address(pte)) goto bad;
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if (bad_address(pte))
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goto bad;
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printk("PTE %lx", pte_val(*pte));
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ret:
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out:
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printk("\n");
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return;
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bad:
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@ -285,7 +309,6 @@ static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
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* and redundant with the set_pmd() on non-PAE. As would
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* set_pud.
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*/
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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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@ -295,11 +318,14 @@ static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long 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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arch_flush_lazy_mmu_mode();
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} else
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} else {
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BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k));
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}
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return pmd_k;
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}
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#endif
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@ -312,29 +338,37 @@ KERN_ERR "******* Please consider a BIOS update.\n"
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KERN_ERR "******* Disabling USB legacy in the BIOS may also help.\n";
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#endif
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/* Workaround for K8 erratum #93 & buggy BIOS.
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BIOS SMM functions are required to use a specific workaround
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to avoid corruption of the 64bit RIP register on C stepping K8.
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A lot of BIOS that didn't get tested properly miss this.
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The OS sees this as a page fault with the upper 32bits of RIP cleared.
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Try to work around it here.
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Note we only handle faults in kernel here.
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Does nothing for X86_32
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/*
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* Workaround for K8 erratum #93 & buggy BIOS.
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*
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* BIOS SMM functions are required to use a specific workaround
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* to avoid corruption of the 64bit RIP register on C stepping K8.
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*
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* A lot of BIOS that didn't get tested properly miss this.
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*
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* The OS sees this as a page fault with the upper 32bits of RIP cleared.
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* Try to work around it here.
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*
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* Note we only handle faults in kernel here.
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* Does nothing on 32-bit.
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*/
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static int is_errata93(struct pt_regs *regs, unsigned long address)
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{
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#ifdef CONFIG_X86_64
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static int warned;
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static int once;
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if (address != regs->ip)
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return 0;
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if ((address >> 32) != 0)
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return 0;
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address |= 0xffffffffUL << 32;
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if ((address >= (u64)_stext && address <= (u64)_etext) ||
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(address >= MODULES_VADDR && address <= MODULES_END)) {
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if (!warned) {
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if (!once) {
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printk(errata93_warning);
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warned = 1;
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once = 1;
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}
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regs->ip = address;
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return 1;
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@ -344,16 +378,17 @@ static int is_errata93(struct pt_regs *regs, unsigned long address)
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}
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/*
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* Work around K8 erratum #100 K8 in compat mode occasionally jumps to illegal
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* addresses >4GB. We catch this in the page fault handler because these
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* addresses are not reachable. Just detect this case and return. Any code
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* Work around K8 erratum #100 K8 in compat mode occasionally jumps
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* to illegal addresses >4GB.
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*
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* We catch this in the page fault handler because these addresses
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* are not reachable. Just detect this case and return. Any code
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* segment in LDT is compatibility mode.
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*/
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static int is_errata100(struct pt_regs *regs, unsigned long address)
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{
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#ifdef CONFIG_X86_64
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if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) &&
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(address >> 32))
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if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) && (address >> 32))
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return 1;
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#endif
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return 0;
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@ -363,8 +398,9 @@ static int is_f00f_bug(struct pt_regs *regs, unsigned long address)
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{
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#ifdef CONFIG_X86_F00F_BUG
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unsigned long nr;
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/*
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* Pentium F0 0F C7 C8 bug workaround.
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* Pentium F0 0F C7 C8 bug workaround:
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*/
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if (boot_cpu_data.f00f_bug) {
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nr = (address - idt_descr.address) >> 3;
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@ -378,7 +414,8 @@ static int is_f00f_bug(struct pt_regs *regs, unsigned long address)
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return 0;
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}
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static void show_fault_oops(struct pt_regs *regs, unsigned long error_code,
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static void
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show_fault_oops(struct pt_regs *regs, unsigned long error_code,
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unsigned long address)
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{
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#ifdef CONFIG_X86_32
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@ -389,13 +426,15 @@ static void show_fault_oops(struct pt_regs *regs, unsigned long error_code,
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#ifdef CONFIG_X86_PAE
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if (error_code & PF_INSTR) {
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unsigned int level;
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pte_t *pte = lookup_address(address, &level);
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if (pte && pte_present(*pte) && !pte_exec(*pte))
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if (pte && pte_present(*pte) && !pte_exec(*pte)) {
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printk(KERN_CRIT "kernel tried to execute "
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"NX-protected page - exploit attempt? "
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"(uid: %d)\n", current_uid());
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}
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}
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#endif
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printk(KERN_ALERT "BUG: unable to handle kernel ");
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@ -403,34 +442,45 @@ static void show_fault_oops(struct pt_regs *regs, unsigned long error_code,
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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 %p\n", (void *) address);
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printk(KERN_ALERT "IP:");
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printk_address(regs->ip, 1);
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dump_pagetable(address);
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}
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#ifdef CONFIG_X86_64
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static noinline void pgtable_bad(struct pt_regs *regs,
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unsigned long error_code, unsigned long address)
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static noinline void
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pgtable_bad(struct pt_regs *regs, unsigned long error_code,
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unsigned long address)
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{
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unsigned long flags = oops_begin();
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int sig = SIGKILL;
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struct task_struct *tsk = current;
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struct task_struct *tsk;
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unsigned long flags;
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int sig;
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flags = oops_begin();
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tsk = current;
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sig = SIGKILL;
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printk(KERN_ALERT "%s: Corrupted page table at address %lx\n",
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tsk->comm, address);
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dump_pagetable(address);
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tsk->thread.cr2 = address;
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tsk->thread.trap_no = 14;
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tsk->thread.error_code = error_code;
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if (__die("Bad pagetable", regs, error_code))
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sig = 0;
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oops_end(flags, regs, sig);
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}
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#endif
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static noinline void no_context(struct pt_regs *regs,
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unsigned long error_code, unsigned long address)
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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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struct task_struct *tsk = current;
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unsigned long *stackend;
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@ -445,12 +495,14 @@ static noinline void no_context(struct pt_regs *regs,
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return;
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/*
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* X86_32
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* 32-bit:
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*
|
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* Valid to do another page fault here, because if this fault
|
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* had been triggered by is_prefetch fixup_exception would have
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* handled it.
|
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*
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* X86_64
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* 64-bit:
|
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*
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* Hall of shame of CPU/BIOS bugs.
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*/
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if (is_prefetch(regs, error_code, address))
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@ -461,7 +513,7 @@ static noinline void no_context(struct pt_regs *regs,
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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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* terminate things with extreme prejudice:
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*/
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#ifdef CONFIG_X86_32
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bust_spinlocks(1);
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@ -487,28 +539,54 @@ static noinline void no_context(struct pt_regs *regs,
|
||||
sig = SIGKILL;
|
||||
if (__die("Oops", regs, error_code))
|
||||
sig = 0;
|
||||
|
||||
/* Executive summary in case the body of the oops scrolled away */
|
||||
printk(KERN_EMERG "CR2: %016lx\n", address);
|
||||
|
||||
oops_end(flags, regs, sig);
|
||||
#endif
|
||||
}
|
||||
|
||||
static void __bad_area_nosemaphore(struct pt_regs *regs,
|
||||
unsigned long error_code, unsigned long address,
|
||||
int si_code)
|
||||
/*
|
||||
* Print out info about fatal segfaults, if the show_unhandled_signals
|
||||
* sysctl is set:
|
||||
*/
|
||||
static inline void
|
||||
show_signal_msg(struct pt_regs *regs, unsigned long error_code,
|
||||
unsigned long address, struct task_struct *tsk)
|
||||
{
|
||||
if (!unhandled_signal(tsk, SIGSEGV))
|
||||
return;
|
||||
|
||||
if (!printk_ratelimit())
|
||||
return;
|
||||
|
||||
printk(KERN_CONT "%s%s[%d]: segfault at %lx ip %p sp %p error %lx",
|
||||
task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
|
||||
tsk->comm, task_pid_nr(tsk), address,
|
||||
(void *)regs->ip, (void *)regs->sp, error_code);
|
||||
|
||||
print_vma_addr(KERN_CONT " in ", regs->ip);
|
||||
|
||||
printk(KERN_CONT "\n");
|
||||
}
|
||||
|
||||
static void
|
||||
__bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
|
||||
unsigned long address, int si_code)
|
||||
{
|
||||
struct task_struct *tsk = current;
|
||||
|
||||
/* User mode accesses just cause a SIGSEGV */
|
||||
if (error_code & PF_USER) {
|
||||
/*
|
||||
* It's possible to have interrupts off here.
|
||||
* It's possible to have interrupts off here:
|
||||
*/
|
||||
local_irq_enable();
|
||||
|
||||
/*
|
||||
* Valid to do another page fault here because this one came
|
||||
* from user space.
|
||||
* from user space:
|
||||
*/
|
||||
if (is_prefetch(regs, error_code, address))
|
||||
return;
|
||||
@ -516,22 +594,16 @@ static void __bad_area_nosemaphore(struct pt_regs *regs,
|
||||
if (is_errata100(regs, address))
|
||||
return;
|
||||
|
||||
if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
|
||||
printk_ratelimit()) {
|
||||
printk(
|
||||
"%s%s[%d]: segfault at %lx ip %p sp %p error %lx",
|
||||
task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
|
||||
tsk->comm, task_pid_nr(tsk), address,
|
||||
(void *) regs->ip, (void *) regs->sp, error_code);
|
||||
print_vma_addr(" in ", regs->ip);
|
||||
printk("\n");
|
||||
}
|
||||
if (unlikely(show_unhandled_signals))
|
||||
show_signal_msg(regs, error_code, address, tsk);
|
||||
|
||||
/* Kernel addresses are always protection faults: */
|
||||
tsk->thread.cr2 = address;
|
||||
/* Kernel addresses are always protection faults */
|
||||
tsk->thread.error_code = error_code | (address >= TASK_SIZE);
|
||||
tsk->thread.trap_no = 14;
|
||||
|
||||
force_sig_info_fault(SIGSEGV, si_code, address, tsk);
|
||||
|
||||
return;
|
||||
}
|
||||
|
||||
@ -541,15 +613,16 @@ static void __bad_area_nosemaphore(struct pt_regs *regs,
|
||||
no_context(regs, error_code, address);
|
||||
}
|
||||
|
||||
static noinline void bad_area_nosemaphore(struct pt_regs *regs,
|
||||
unsigned long error_code, unsigned long address)
|
||||
static noinline void
|
||||
bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
|
||||
unsigned long address)
|
||||
{
|
||||
__bad_area_nosemaphore(regs, error_code, address, SEGV_MAPERR);
|
||||
}
|
||||
|
||||
static void __bad_area(struct pt_regs *regs,
|
||||
unsigned long error_code, unsigned long address,
|
||||
int si_code)
|
||||
static void
|
||||
__bad_area(struct pt_regs *regs, unsigned long error_code,
|
||||
unsigned long address, int si_code)
|
||||
{
|
||||
struct mm_struct *mm = current->mm;
|
||||
|
||||
@ -562,67 +635,77 @@ static void __bad_area(struct pt_regs *regs,
|
||||
__bad_area_nosemaphore(regs, error_code, address, si_code);
|
||||
}
|
||||
|
||||
static noinline void bad_area(struct pt_regs *regs,
|
||||
unsigned long error_code, unsigned long address)
|
||||
static noinline void
|
||||
bad_area(struct pt_regs *regs, unsigned long error_code, unsigned long address)
|
||||
{
|
||||
__bad_area(regs, error_code, address, SEGV_MAPERR);
|
||||
}
|
||||
|
||||
static noinline void bad_area_access_error(struct pt_regs *regs,
|
||||
unsigned long error_code, unsigned long address)
|
||||
static noinline void
|
||||
bad_area_access_error(struct pt_regs *regs, unsigned long error_code,
|
||||
unsigned long address)
|
||||
{
|
||||
__bad_area(regs, error_code, address, SEGV_ACCERR);
|
||||
}
|
||||
|
||||
/* TODO: fixup for "mm-invoke-oom-killer-from-page-fault.patch" */
|
||||
static void out_of_memory(struct pt_regs *regs,
|
||||
unsigned long error_code, unsigned long address)
|
||||
static void
|
||||
out_of_memory(struct pt_regs *regs, unsigned long error_code,
|
||||
unsigned long address)
|
||||
{
|
||||
/*
|
||||
* We ran out of memory, call the OOM killer, and return the userspace
|
||||
* (which will retry the fault, or kill us if we got oom-killed).
|
||||
* (which will retry the fault, or kill us if we got oom-killed):
|
||||
*/
|
||||
up_read(¤t->mm->mmap_sem);
|
||||
|
||||
pagefault_out_of_memory();
|
||||
}
|
||||
|
||||
static void do_sigbus(struct pt_regs *regs,
|
||||
unsigned long error_code, unsigned long address)
|
||||
static void
|
||||
do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address)
|
||||
{
|
||||
struct task_struct *tsk = current;
|
||||
struct mm_struct *mm = tsk->mm;
|
||||
|
||||
up_read(&mm->mmap_sem);
|
||||
|
||||
/* Kernel mode? Handle exceptions or die */
|
||||
/* Kernel mode? Handle exceptions or die: */
|
||||
if (!(error_code & PF_USER))
|
||||
no_context(regs, error_code, address);
|
||||
|
||||
#ifdef CONFIG_X86_32
|
||||
/* User space => ok to do another page fault */
|
||||
/* User space => ok to do another page fault: */
|
||||
if (is_prefetch(regs, error_code, address))
|
||||
return;
|
||||
#endif
|
||||
|
||||
tsk->thread.cr2 = address;
|
||||
tsk->thread.error_code = error_code;
|
||||
tsk->thread.trap_no = 14;
|
||||
|
||||
force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk);
|
||||
}
|
||||
|
||||
static noinline void mm_fault_error(struct pt_regs *regs,
|
||||
unsigned long error_code, unsigned long address, unsigned int fault)
|
||||
static noinline void
|
||||
mm_fault_error(struct pt_regs *regs, unsigned long error_code,
|
||||
unsigned long address, unsigned int fault)
|
||||
{
|
||||
if (fault & VM_FAULT_OOM)
|
||||
if (fault & VM_FAULT_OOM) {
|
||||
out_of_memory(regs, error_code, address);
|
||||
else if (fault & VM_FAULT_SIGBUS)
|
||||
} else {
|
||||
if (fault & VM_FAULT_SIGBUS)
|
||||
do_sigbus(regs, error_code, address);
|
||||
else
|
||||
BUG();
|
||||
}
|
||||
}
|
||||
|
||||
static int spurious_fault_check(unsigned long error_code, pte_t *pte)
|
||||
{
|
||||
if ((error_code & PF_WRITE) && !pte_write(*pte))
|
||||
return 0;
|
||||
|
||||
if ((error_code & PF_INSTR) && !pte_exec(*pte))
|
||||
return 0;
|
||||
|
||||
@ -630,16 +713,19 @@ static int spurious_fault_check(unsigned long error_code, pte_t *pte)
|
||||
}
|
||||
|
||||
/*
|
||||
* Handle a spurious fault caused by a stale TLB entry. This allows
|
||||
* us to lazily refresh the TLB when increasing the permissions of a
|
||||
* kernel page (RO -> RW or NX -> X). Doing it eagerly is very
|
||||
* expensive since that implies doing a full cross-processor TLB
|
||||
* flush, even if no stale TLB entries exist on other processors.
|
||||
* Handle a spurious fault caused by a stale TLB entry.
|
||||
*
|
||||
* This allows us to lazily refresh the TLB when increasing the
|
||||
* permissions of a kernel page (RO -> RW or NX -> X). Doing it
|
||||
* eagerly is very expensive since that implies doing a full
|
||||
* cross-processor TLB flush, even if no stale TLB entries exist
|
||||
* on other processors.
|
||||
*
|
||||
* There are no security implications to leaving a stale TLB when
|
||||
* increasing the permissions on a page.
|
||||
*/
|
||||
static noinline int spurious_fault(unsigned long error_code,
|
||||
unsigned long address)
|
||||
static noinline int
|
||||
spurious_fault(unsigned long error_code, unsigned long address)
|
||||
{
|
||||
pgd_t *pgd;
|
||||
pud_t *pud;
|
||||
@ -678,19 +764,22 @@ static noinline int spurious_fault(unsigned long error_code,
|
||||
return 0;
|
||||
|
||||
/*
|
||||
* Make sure we have permissions in PMD
|
||||
* If not, then there's a bug in the page tables.
|
||||
* Make sure we have permissions in PMD.
|
||||
* If not, then there's a bug in the page tables:
|
||||
*/
|
||||
ret = spurious_fault_check(error_code, (pte_t *) pmd);
|
||||
WARN_ONCE(!ret, "PMD has incorrect permission bits\n");
|
||||
|
||||
return ret;
|
||||
}
|
||||
|
||||
/*
|
||||
* X86_32
|
||||
* 32-bit:
|
||||
*
|
||||
* Handle a fault on the vmalloc or module mapping area
|
||||
*
|
||||
* X86_64
|
||||
* 64-bit:
|
||||
*
|
||||
* Handle a fault on the vmalloc area
|
||||
*
|
||||
* This assumes no large pages in there.
|
||||
@ -702,7 +791,7 @@ static noinline int vmalloc_fault(unsigned long address)
|
||||
pmd_t *pmd_k;
|
||||
pte_t *pte_k;
|
||||
|
||||
/* Make sure we are in vmalloc area */
|
||||
/* Make sure we are in vmalloc area: */
|
||||
if (!(address >= VMALLOC_START && address < VMALLOC_END))
|
||||
return -1;
|
||||
|
||||
@ -717,9 +806,11 @@ static noinline int vmalloc_fault(unsigned long address)
|
||||
pmd_k = vmalloc_sync_one(__va(pgd_paddr), address);
|
||||
if (!pmd_k)
|
||||
return -1;
|
||||
|
||||
pte_k = pte_offset_kernel(pmd_k, address);
|
||||
if (!pte_present(*pte_k))
|
||||
return -1;
|
||||
|
||||
return 0;
|
||||
#else
|
||||
pgd_t *pgd, *pgd_ref;
|
||||
@ -727,68 +818,83 @@ static noinline int vmalloc_fault(unsigned long address)
|
||||
pmd_t *pmd, *pmd_ref;
|
||||
pte_t *pte, *pte_ref;
|
||||
|
||||
/* Make sure we are in vmalloc area */
|
||||
/* Make sure we are in vmalloc area: */
|
||||
if (!(address >= VMALLOC_START && address < VMALLOC_END))
|
||||
return -1;
|
||||
|
||||
/* Copy kernel mappings over when needed. This can also
|
||||
happen within a race in page table update. In the later
|
||||
case just flush. */
|
||||
|
||||
/*
|
||||
* Copy kernel mappings over when needed. This can also
|
||||
* happen within a race in page table update. In the later
|
||||
* case just flush:
|
||||
*/
|
||||
pgd = pgd_offset(current->active_mm, address);
|
||||
pgd_ref = pgd_offset_k(address);
|
||||
if (pgd_none(*pgd_ref))
|
||||
return -1;
|
||||
|
||||
if (pgd_none(*pgd))
|
||||
set_pgd(pgd, *pgd_ref);
|
||||
else
|
||||
BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref));
|
||||
|
||||
/* Below here mismatches are bugs because these lower tables
|
||||
are shared */
|
||||
/*
|
||||
* Below here mismatches are bugs because these lower tables
|
||||
* are shared:
|
||||
*/
|
||||
|
||||
pud = pud_offset(pgd, address);
|
||||
pud_ref = pud_offset(pgd_ref, address);
|
||||
if (pud_none(*pud_ref))
|
||||
return -1;
|
||||
|
||||
if (pud_none(*pud) || pud_page_vaddr(*pud) != pud_page_vaddr(*pud_ref))
|
||||
BUG();
|
||||
|
||||
pmd = pmd_offset(pud, address);
|
||||
pmd_ref = pmd_offset(pud_ref, address);
|
||||
if (pmd_none(*pmd_ref))
|
||||
return -1;
|
||||
|
||||
if (pmd_none(*pmd) || pmd_page(*pmd) != pmd_page(*pmd_ref))
|
||||
BUG();
|
||||
|
||||
pte_ref = pte_offset_kernel(pmd_ref, address);
|
||||
if (!pte_present(*pte_ref))
|
||||
return -1;
|
||||
|
||||
pte = pte_offset_kernel(pmd, address);
|
||||
/* Don't use pte_page here, because the mappings can point
|
||||
outside mem_map, and the NUMA hash lookup cannot handle
|
||||
that. */
|
||||
|
||||
/*
|
||||
* Don't use pte_page here, because the mappings can point
|
||||
* outside mem_map, and the NUMA hash lookup cannot handle
|
||||
* that:
|
||||
*/
|
||||
if (!pte_present(*pte) || pte_pfn(*pte) != pte_pfn(*pte_ref))
|
||||
BUG();
|
||||
|
||||
return 0;
|
||||
#endif
|
||||
}
|
||||
|
||||
int show_unhandled_signals = 1;
|
||||
|
||||
static inline int access_error(unsigned long error_code, int write,
|
||||
struct vm_area_struct *vma)
|
||||
static inline int
|
||||
access_error(unsigned long error_code, int write, struct vm_area_struct *vma)
|
||||
{
|
||||
if (write) {
|
||||
/* write, present and write, not present */
|
||||
/* write, present and write, not present: */
|
||||
if (unlikely(!(vma->vm_flags & VM_WRITE)))
|
||||
return 1;
|
||||
} else if (unlikely(error_code & PF_PROT)) {
|
||||
/* read, present */
|
||||
return 0;
|
||||
}
|
||||
|
||||
/* read, present: */
|
||||
if (unlikely(error_code & PF_PROT))
|
||||
return 1;
|
||||
} else {
|
||||
/* read, not present */
|
||||
|
||||
/* read, not present: */
|
||||
if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))))
|
||||
return 1;
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
@ -797,9 +903,9 @@ static int fault_in_kernel_space(unsigned long address)
|
||||
{
|
||||
#ifdef CONFIG_X86_32
|
||||
return address >= TASK_SIZE;
|
||||
#else /* !CONFIG_X86_32 */
|
||||
#else
|
||||
return address >= TASK_SIZE64;
|
||||
#endif /* CONFIG_X86_32 */
|
||||
#endif
|
||||
}
|
||||
|
||||
/*
|
||||
@ -812,18 +918,19 @@ asmlinkage
|
||||
#endif
|
||||
void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
|
||||
{
|
||||
unsigned long address;
|
||||
struct task_struct *tsk;
|
||||
struct mm_struct *mm;
|
||||
struct vm_area_struct *vma;
|
||||
struct task_struct *tsk;
|
||||
unsigned long address;
|
||||
struct mm_struct *mm;
|
||||
int write;
|
||||
int fault;
|
||||
|
||||
tsk = current;
|
||||
mm = tsk->mm;
|
||||
|
||||
prefetchw(&mm->mmap_sem);
|
||||
|
||||
/* get the address */
|
||||
/* Get the faulting address: */
|
||||
address = read_cr2();
|
||||
|
||||
if (unlikely(kmmio_fault(regs, address)))
|
||||
@ -847,22 +954,23 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
|
||||
vmalloc_fault(address) >= 0)
|
||||
return;
|
||||
|
||||
/* Can handle a stale RO->RW TLB */
|
||||
/* Can handle a stale RO->RW TLB: */
|
||||
if (spurious_fault(error_code, address))
|
||||
return;
|
||||
|
||||
/* kprobes don't want to hook the spurious faults. */
|
||||
/* kprobes don't want to hook the spurious faults: */
|
||||
if (notify_page_fault(regs))
|
||||
return;
|
||||
/*
|
||||
* Don't take the mm semaphore here. If we fixup a prefetch
|
||||
* fault we could otherwise deadlock.
|
||||
* fault we could otherwise deadlock:
|
||||
*/
|
||||
bad_area_nosemaphore(regs, error_code, address);
|
||||
|
||||
return;
|
||||
}
|
||||
|
||||
/* kprobes don't want to hook the spurious faults. */
|
||||
/* kprobes don't want to hook the spurious faults: */
|
||||
if (unlikely(notify_page_fault(regs)))
|
||||
return;
|
||||
/*
|
||||
@ -870,13 +978,15 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
|
||||
* vmalloc fault has been handled.
|
||||
*
|
||||
* User-mode registers count as a user access even for any
|
||||
* potential system fault or CPU buglet.
|
||||
* potential system fault or CPU buglet:
|
||||
*/
|
||||
if (user_mode_vm(regs)) {
|
||||
local_irq_enable();
|
||||
error_code |= PF_USER;
|
||||
} else if (regs->flags & X86_EFLAGS_IF)
|
||||
} else {
|
||||
if (regs->flags & X86_EFLAGS_IF)
|
||||
local_irq_enable();
|
||||
}
|
||||
|
||||
#ifdef CONFIG_X86_64
|
||||
if (unlikely(error_code & PF_RSVD))
|
||||
@ -884,8 +994,8 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
|
||||
#endif
|
||||
|
||||
/*
|
||||
* If we're in an interrupt, have no user context or are running in an
|
||||
* atomic region then we must not take the fault.
|
||||
* If we're in an interrupt, have no user context or are running
|
||||
* in an atomic region then we must not take the fault:
|
||||
*/
|
||||
if (unlikely(in_atomic() || !mm)) {
|
||||
bad_area_nosemaphore(regs, error_code, address);
|
||||
@ -894,19 +1004,19 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
|
||||
|
||||
/*
|
||||
* 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.
|
||||
* 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.
|
||||
* 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 (unlikely(!down_read_trylock(&mm->mmap_sem))) {
|
||||
if ((error_code & PF_USER) == 0 &&
|
||||
@ -917,8 +1027,9 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
|
||||
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().
|
||||
* The above down_read_trylock() might have succeeded in
|
||||
* which case we'll have missed the might_sleep() from
|
||||
* down_read():
|
||||
*/
|
||||
might_sleep();
|
||||
}
|
||||
@ -938,7 +1049,7 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
|
||||
/*
|
||||
* Accessing the stack below %sp is always a bug.
|
||||
* The large cushion allows instructions like enter
|
||||
* and pusha to work. ("enter $65535,$31" pushes
|
||||
* and pusha to work. ("enter $65535, $31" pushes
|
||||
* 32 pointers and then decrements %sp by 65535.)
|
||||
*/
|
||||
if (unlikely(address + 65536 + 32 * sizeof(unsigned long) < regs->sp)) {
|
||||
@ -957,6 +1068,7 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
|
||||
*/
|
||||
good_area:
|
||||
write = error_code & PF_WRITE;
|
||||
|
||||
if (unlikely(access_error(error_code, write, vma))) {
|
||||
bad_area_access_error(regs, error_code, address);
|
||||
return;
|
||||
@ -965,13 +1077,15 @@ good_area:
|
||||
/*
|
||||
* If for any reason at all we couldn't handle the fault,
|
||||
* make sure we exit gracefully rather than endlessly redo
|
||||
* the fault.
|
||||
* the fault:
|
||||
*/
|
||||
fault = handle_mm_fault(mm, vma, address, write);
|
||||
|
||||
if (unlikely(fault & VM_FAULT_ERROR)) {
|
||||
mm_fault_error(regs, error_code, address, fault);
|
||||
return;
|
||||
}
|
||||
|
||||
if (fault & VM_FAULT_MAJOR)
|
||||
tsk->maj_flt++;
|
||||
else
|
||||
@ -1004,13 +1118,13 @@ void vmalloc_sync_all(void)
|
||||
for (address = VMALLOC_START & PMD_MASK;
|
||||
address >= TASK_SIZE && address < FIXADDR_TOP;
|
||||
address += PMD_SIZE) {
|
||||
|
||||
unsigned long flags;
|
||||
struct page *page;
|
||||
|
||||
spin_lock_irqsave(&pgd_lock, flags);
|
||||
list_for_each_entry(page, &pgd_list, lru) {
|
||||
if (!vmalloc_sync_one(page_address(page),
|
||||
address))
|
||||
if (!vmalloc_sync_one(page_address(page), address))
|
||||
break;
|
||||
}
|
||||
spin_unlock_irqrestore(&pgd_lock, flags);
|
||||
@ -1018,12 +1132,14 @@ void vmalloc_sync_all(void)
|
||||
#else /* CONFIG_X86_64 */
|
||||
for (address = VMALLOC_START & PGDIR_MASK; address <= VMALLOC_END;
|
||||
address += PGDIR_SIZE) {
|
||||
|
||||
const pgd_t *pgd_ref = pgd_offset_k(address);
|
||||
unsigned long flags;
|
||||
struct page *page;
|
||||
|
||||
if (pgd_none(*pgd_ref))
|
||||
continue;
|
||||
|
||||
spin_lock_irqsave(&pgd_lock, flags);
|
||||
list_for_each_entry(page, &pgd_list, lru) {
|
||||
pgd_t *pgd;
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user