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Commit 2d4a7167 authored by Ingo Molnar's avatar Ingo Molnar
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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: default avatarIngo Molnar <mingo@elte.hu>
parent c9e1585b
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Showing with 331 additions and 215 deletions
arch/x86/mm/fault.c
View file @ 2d4a7167
/*
* Copyright (C) 1995 Linus Torvalds
* Copyright (C) 2001,2002 Andi Kleen, SuSE Labs.
* Copyright (C) 2001, 2002 Andi Kleen, SuSE Labs.
*/
#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/mmiotrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/tty.h>
#include <linux/vt_kern.h> /* For unblank_screen() */
#include <linux/mmiotrace.h>
#include <linux/bootmem.h>
#include <linux/compiler.h>
#include <linux/highmem.h>
#include <linux/bootmem.h> /* for max_low_pfn */
#include <linux/vmalloc.h>
#include <linux/module.h>
#include <linux/kprobes.h>
#include <linux/uaccess.h>
#include <linux/vmalloc.h>
#include <linux/vt_kern.h>
#include <linux/signal.h>
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/string.h>
#include <linux/module.h>
#include <linux/kdebug.h>
#include <linux/errno.h>
#include <linux/magic.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/mman.h>
#include <linux/tty.h>
#include <linux/smp.h>
#include <linux/mm.h>
#include <asm-generic/sections.h>
#include <asm/system.h>
#include <asm/desc.h>
#include <asm/segment.h>
#include <asm/pgalloc.h>
#include <asm/smp.h>
#include <asm/tlbflush.h>
#include <asm/pgalloc.h>
#include <asm/segment.h>
#include <asm/system.h>
#include <asm/proto.h>
#include <asm-generic/sections.h>
#include <asm/traps.h>
#include <asm/desc.h>
/*
* Page fault error code bits
* bit 0 == 0 means no page found, 1 means protection fault
* bit 1 == 0 means read, 1 means write
* bit 2 == 0 means kernel, 1 means user-mode
* bit 3 == 1 means use of reserved bit detected
* bit 4 == 1 means fault was an instruction fetch
* Page fault error code bits:
*
* bit 0 == 0: no page found 1: protection fault
* bit 1 == 0: read access 1: write access
* bit 2 == 0: kernel-mode access 1: user-mode access
* bit 3 == 1: use of reserved bit detected
* bit 4 == 1: fault was an instruction fetch
*/
#define PF_PROT (1<<0)
#define PF_WRITE (1<<1)
#define PF_USER (1<<2)
#define PF_RSVD (1<<3)
#define PF_INSTR (1<<4)
enum x86_pf_error_code {
PF_PROT = 1 << 0,
PF_WRITE = 1 << 1,
PF_USER = 1 << 2,
PF_RSVD = 1 << 3,
PF_INSTR = 1 << 4,
};
static inline int kmmio_fault(struct pt_regs *regs, unsigned long addr)
{
......@@ -82,23 +85,27 @@ static inline int notify_page_fault(struct pt_regs *regs)
}
/*
* X86_32
* Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch.
* Check that here and ignore it.
* Prefetch quirks:
*
* 32-bit mode:
*
* Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch.
* Check that here and ignore it.
*
* X86_64
* Sometimes the CPU reports invalid exceptions on prefetch.
* Check that here and ignore it.
* 64-bit mode:
*
* Opcode checker based on code by Richard Brunner
* Sometimes the CPU reports invalid exceptions on prefetch.
* Check that here and ignore it.
*
* Opcode checker based on code by Richard Brunner.
*/
static int is_prefetch(struct pt_regs *regs, unsigned long error_code,
unsigned long addr)
static int
is_prefetch(struct pt_regs *regs, unsigned long error_code, unsigned long addr)
{
unsigned char *max_instr;
unsigned char *instr;
int scan_more = 1;
int prefetch = 0;
unsigned char *max_instr;
/*
* If it was a exec (instruction fetch) fault on NX page, then
......@@ -114,9 +121,9 @@ static int is_prefetch(struct pt_regs *regs, unsigned long error_code,
return 0;
while (scan_more && instr < max_instr) {
unsigned char opcode;
unsigned char instr_hi;
unsigned char instr_lo;
unsigned char opcode;
if (probe_kernel_address(instr, opcode))
break;
......@@ -173,15 +180,17 @@ static int is_prefetch(struct pt_regs *regs, unsigned long error_code,
return prefetch;
}
static void force_sig_info_fault(int si_signo, int si_code,
unsigned long address, struct task_struct *tsk)
static void
force_sig_info_fault(int si_signo, int si_code, unsigned long address,
struct task_struct *tsk)
{
siginfo_t info;
info.si_signo = si_signo;
info.si_errno = 0;
info.si_code = si_code;
info.si_addr = (void __user *)address;
info.si_signo = si_signo;
info.si_errno = 0;
info.si_code = si_code;
info.si_addr = (void __user *)address;
force_sig_info(si_signo, &info, tsk);
}
......@@ -189,6 +198,7 @@ static void force_sig_info_fault(int si_signo, int si_code,
static int bad_address(void *p)
{
unsigned long dummy;
return probe_kernel_address((unsigned long *)p, dummy);
}
#endif
......@@ -200,13 +210,14 @@ static void dump_pagetable(unsigned long address)
page = read_cr3();
page = ((__typeof__(page) *) __va(page))[address >> PGDIR_SHIFT];
#ifdef CONFIG_X86_PAE
printk("*pdpt = %016Lx ", page);
if ((page >> PAGE_SHIFT) < max_low_pfn
&& page & _PAGE_PRESENT) {
page &= PAGE_MASK;
page = ((__typeof__(page) *) __va(page))[(address >> PMD_SHIFT)
& (PTRS_PER_PMD - 1)];
& (PTRS_PER_PMD - 1)];
printk(KERN_CONT "*pde = %016Lx ", page);
page &= ~_PAGE_NX;
}
......@@ -218,14 +229,15 @@ static void dump_pagetable(unsigned long address)
* We must not directly access the pte in the highpte
* case if the page table is located in highmem.
* And let's rather not kmap-atomic the pte, just in case
* it's allocated already.
* it's allocated already:
*/
if ((page >> PAGE_SHIFT) < max_low_pfn
&& (page & _PAGE_PRESENT)
&& !(page & _PAGE_PSE)) {
page &= PAGE_MASK;
page = ((__typeof__(page) *) __va(page))[(address >> PAGE_SHIFT)
& (PTRS_PER_PTE - 1)];
& (PTRS_PER_PTE - 1)];
printk("*pte = %0*Lx ", sizeof(page)*2, (u64)page);
}
......@@ -239,26 +251,38 @@ static void dump_pagetable(unsigned long address)
pgd = (pgd_t *)read_cr3();
pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK);
pgd += pgd_index(address);
if (bad_address(pgd)) goto bad;
if (bad_address(pgd))
goto bad;
printk("PGD %lx ", pgd_val(*pgd));
if (!pgd_present(*pgd)) goto ret;
if (!pgd_present(*pgd))
goto out;
pud = pud_offset(pgd, address);
if (bad_address(pud)) goto bad;
if (bad_address(pud))
goto bad;
printk("PUD %lx ", pud_val(*pud));
if (!pud_present(*pud) || pud_large(*pud))
goto ret;
goto out;
pmd = pmd_offset(pud, address);
if (bad_address(pmd)) goto bad;
if (bad_address(pmd))
goto bad;
printk("PMD %lx ", pmd_val(*pmd));
if (!pmd_present(*pmd) || pmd_large(*pmd)) goto ret;
if (!pmd_present(*pmd) || pmd_large(*pmd))
goto out;
pte = pte_offset_kernel(pmd, address);
if (bad_address(pte)) goto bad;
if (bad_address(pte))
goto bad;
printk("PTE %lx", pte_val(*pte));
ret:
out:
printk("\n");
return;
bad:
......@@ -285,7 +309,6 @@ static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
* and redundant with the set_pmd() on non-PAE. As would
* set_pud.
*/
pud = pud_offset(pgd, address);
pud_k = pud_offset(pgd_k, address);
if (!pud_present(*pud_k))
......@@ -295,11 +318,14 @@ static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
pmd_k = pmd_offset(pud_k, address);
if (!pmd_present(*pmd_k))
return NULL;
if (!pmd_present(*pmd)) {
set_pmd(pmd, *pmd_k);
arch_flush_lazy_mmu_mode();
} else
} else {
BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k));
}
return pmd_k;
}
#endif
......@@ -312,29 +338,37 @@ KERN_ERR "******* Please consider a BIOS update.\n"
KERN_ERR "******* Disabling USB legacy in the BIOS may also help.\n";
#endif
/* Workaround for K8 erratum #93 & buggy BIOS.
BIOS SMM functions are required to use a specific workaround
to avoid corruption of the 64bit RIP register on C stepping K8.
A lot of BIOS that didn't get tested properly miss this.
The OS sees this as a page fault with the upper 32bits of RIP cleared.
Try to work around it here.
Note we only handle faults in kernel here.
Does nothing for X86_32
/*
* Workaround for K8 erratum #93 & buggy BIOS.
*
* BIOS SMM functions are required to use a specific workaround
* to avoid corruption of the 64bit RIP register on C stepping K8.
*
* A lot of BIOS that didn't get tested properly miss this.
*
* The OS sees this as a page fault with the upper 32bits of RIP cleared.
* Try to work around it here.
*
* Note we only handle faults in kernel here.
* Does nothing on 32-bit.
*/
static int is_errata93(struct pt_regs *regs, unsigned long address)
{
#ifdef CONFIG_X86_64
static int warned;
static int once;
if (address != regs->ip)
return 0;
if ((address >> 32) != 0)
return 0;
address |= 0xffffffffUL << 32;
if ((address >= (u64)_stext && address <= (u64)_etext) ||
(address >= MODULES_VADDR && address <= MODULES_END)) {
if (!warned) {
if (!once) {
printk(errata93_warning);
warned = 1;
once = 1;
}
regs->ip = address;
return 1;
......@@ -344,16 +378,17 @@ static int is_errata93(struct pt_regs *regs, unsigned long address)
}
/*
* Work around K8 erratum #100 K8 in compat mode occasionally jumps to illegal
* addresses >4GB. We catch this in the page fault handler because these
* addresses are not reachable. Just detect this case and return. Any code
* Work around K8 erratum #100 K8 in compat mode occasionally jumps
* to illegal addresses >4GB.
*
* We catch this in the page fault handler because these addresses
* are not reachable. Just detect this case and return. Any code
* segment in LDT is compatibility mode.
*/
static int is_errata100(struct pt_regs *regs, unsigned long address)
{
#ifdef CONFIG_X86_64
if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) &&
(address >> 32))
if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) && (address >> 32))
return 1;
#endif
return 0;
......@@ -363,8 +398,9 @@ static int is_f00f_bug(struct pt_regs *regs, unsigned long address)
{
#ifdef CONFIG_X86_F00F_BUG
unsigned long nr;
/*
* Pentium F0 0F C7 C8 bug workaround.
* Pentium F0 0F C7 C8 bug workaround:
*/
if (boot_cpu_data.f00f_bug) {
nr = (address - idt_descr.address) >> 3;
......@@ -378,8 +414,9 @@ static int is_f00f_bug(struct pt_regs *regs, unsigned long address)
return 0;
}
static void show_fault_oops(struct pt_regs *regs, unsigned long error_code,
unsigned long address)
static void
show_fault_oops(struct pt_regs *regs, unsigned long error_code,
unsigned long address)
{
#ifdef CONFIG_X86_32
if (!oops_may_print())
......@@ -389,12 +426,14 @@ static void show_fault_oops(struct pt_regs *regs, unsigned long error_code,
#ifdef CONFIG_X86_PAE
if (error_code & PF_INSTR) {
unsigned int level;
pte_t *pte = lookup_address(address, &level);
if (pte && pte_present(*pte) && !pte_exec(*pte))
if (pte && pte_present(*pte) && !pte_exec(*pte)) {
printk(KERN_CRIT "kernel tried to execute "
"NX-protected page - exploit attempt? "
"(uid: %d)\n", current_uid());
}
}
#endif
......@@ -403,34 +442,45 @@ static void show_fault_oops(struct pt_regs *regs, unsigned long error_code,
printk(KERN_CONT "NULL pointer dereference");
else
printk(KERN_CONT "paging request");
printk(KERN_CONT " at %p\n", (void *) address);
printk(KERN_ALERT "IP:");
printk_address(regs->ip, 1);
dump_pagetable(address);
}
#ifdef CONFIG_X86_64
static noinline void pgtable_bad(struct pt_regs *regs,
unsigned long error_code, unsigned long address)
static noinline void
pgtable_bad(struct pt_regs *regs, unsigned long error_code,
unsigned long address)
{
unsigned long flags = oops_begin();
int sig = SIGKILL;
struct task_struct *tsk = current;
struct task_struct *tsk;
unsigned long flags;
int sig;
flags = oops_begin();
tsk = current;
sig = SIGKILL;
printk(KERN_ALERT "%s: Corrupted page table at address %lx\n",
tsk->comm, address);
dump_pagetable(address);
tsk->thread.cr2 = address;
tsk->thread.trap_no = 14;
tsk->thread.error_code = error_code;
tsk->thread.cr2 = address;
tsk->thread.trap_no = 14;
tsk->thread.error_code = error_code;
if (__die("Bad pagetable", regs, error_code))
sig = 0;
oops_end(flags, regs, sig);
}
#endif
static noinline void no_context(struct pt_regs *regs,
unsigned long error_code, unsigned long address)
static noinline void
no_context(struct pt_regs *regs, unsigned long error_code,
unsigned long address)
{
struct task_struct *tsk = current;
unsigned long *stackend;
......@@ -440,18 +490,20 @@ static noinline void no_context(struct pt_regs *regs,
int sig;
#endif
/* Are we prepared to handle this kernel fault? */
/* Are we prepared to handle this kernel fault? */
if (fixup_exception(regs))
return;
/*
* X86_32
* Valid to do another page fault here, because if this fault
* had been triggered by is_prefetch fixup_exception would have
* handled it.
* 32-bit:
*
* Valid to do another page fault here, because if this fault
* had been triggered by is_prefetch fixup_exception would have
* handled it.
*
* 64-bit:
*
* X86_64
* Hall of shame of CPU/BIOS bugs.
* Hall of shame of CPU/BIOS bugs.
*/
if (is_prefetch(regs, error_code, address))
return;
......@@ -461,7 +513,7 @@ static noinline void no_context(struct pt_regs *regs,
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
* terminate things with extreme prejudice:
*/
#ifdef CONFIG_X86_32
bust_spinlocks(1);
......@@ -471,7 +523,7 @@ static noinline void no_context(struct pt_regs *regs,
show_fault_oops(regs, error_code, address);
stackend = end_of_stack(tsk);
stackend = end_of_stack(tsk);
if (*stackend != STACK_END_MAGIC)
printk(KERN_ALERT "Thread overran stack, or stack corrupted\n");
......@@ -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;
tsk->thread.error_code = error_code | (address >= TASK_SIZE);
tsk->thread.trap_no = 14;
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(&current->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;
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)
do_sigbus(regs, error_code, address);
else
BUG();
} 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;
......@@ -678,20 +764,23 @@ 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
* Handle a fault on the vmalloc or module mapping area
* 32-bit:
*
* Handle a fault on the vmalloc or module mapping area
*
* X86_64
* Handle a fault on the vmalloc area
* 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;
......@@ -727,69 +818,84 @@ 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 1;
} else {
/* read, not present */
if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))))
return 1;
return 0;
}
/* read, present: */
if (unlikely(error_code & PF_PROT))
return 1;
/* 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 vm_area_struct *vma;
struct task_struct *tsk;
unsigned long address;
struct mm_struct *mm;
struct vm_area_struct *vma;
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)
local_irq_enable();
} 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;
......
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