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kernel-fxtec-pro1x/arch/i386/kernel/traps.c
Andi Kleen d189518342 [PATCH] x86: Fix i386 and x86_64 fault information pollution 
a userspace fault or a kernelspace fault which will result in the
immediate death of the process.  They should not be filled in as a
result of a kernelspace fault which can be fixed up.

Otherwise, if the process is handling SIGSEGV and examining the fault
information, this can result in the kernel space fault trashing the
previously stored fault information if it arrives between the
userspace fault happening and the SIGSEGV being delivered to the process.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Acked-by: Jan Beulich <jbeulich@novell.com>
--
 arch/i386/kernel/traps.c   |   24 ++++++++++++++++++------
 arch/x86_64/kernel/traps.c |   30 +++++++++++++++++++++++-------
 2 files changed, 41 insertions(+), 13 deletions(-)
2007-05-02 19:27:05 +02:00

1218 lines
31 KiB
C
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/*
* linux/arch/i386/traps.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* Pentium III FXSR, SSE support
* Gareth Hughes <gareth@valinux.com>, May 2000
*/
/*
* 'Traps.c' handles hardware traps and faults after we have saved some
* state in 'asm.s'.
*/
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/highmem.h>
#include <linux/kallsyms.h>
#include <linux/ptrace.h>
#include <linux/utsname.h>
#include <linux/kprobes.h>
#include <linux/kexec.h>
#include <linux/unwind.h>
#include <linux/uaccess.h>
#include <linux/nmi.h>
#include <linux/bug.h>
#ifdef CONFIG_EISA
#include <linux/ioport.h>
#include <linux/eisa.h>
#endif
#ifdef CONFIG_MCA
#include <linux/mca.h>
#endif
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/atomic.h>
#include <asm/debugreg.h>
#include <asm/desc.h>
#include <asm/i387.h>
#include <asm/nmi.h>
#include <asm/unwind.h>
#include <asm/smp.h>
#include <asm/arch_hooks.h>
#include <asm/kdebug.h>
#include <asm/stacktrace.h>
#include <linux/module.h>
#include "mach_traps.h"
int panic_on_unrecovered_nmi;
asmlinkage int system_call(void);
/* Do we ignore FPU interrupts ? */
char ignore_fpu_irq = 0;
/*
* The IDT has to be page-aligned to simplify the Pentium
* F0 0F bug workaround.. We have a special link segment
* for this.
*/
struct desc_struct idt_table[256] __attribute__((__section__(".data.idt"))) = { {0, 0}, };
asmlinkage void divide_error(void);
asmlinkage void debug(void);
asmlinkage void nmi(void);
asmlinkage void int3(void);
asmlinkage void overflow(void);
asmlinkage void bounds(void);
asmlinkage void invalid_op(void);
asmlinkage void device_not_available(void);
asmlinkage void coprocessor_segment_overrun(void);
asmlinkage void invalid_TSS(void);
asmlinkage void segment_not_present(void);
asmlinkage void stack_segment(void);
asmlinkage void general_protection(void);
asmlinkage void page_fault(void);
asmlinkage void coprocessor_error(void);
asmlinkage void simd_coprocessor_error(void);
asmlinkage void alignment_check(void);
asmlinkage void spurious_interrupt_bug(void);
asmlinkage void machine_check(void);
int kstack_depth_to_print = 24;
static unsigned int code_bytes = 64;
ATOMIC_NOTIFIER_HEAD(i386die_chain);
int register_die_notifier(struct notifier_block *nb)
{
vmalloc_sync_all();
return atomic_notifier_chain_register(&i386die_chain, nb);
}
EXPORT_SYMBOL(register_die_notifier); /* used modular by kdb */
int unregister_die_notifier(struct notifier_block *nb)
{
return atomic_notifier_chain_unregister(&i386die_chain, nb);
}
EXPORT_SYMBOL(unregister_die_notifier); /* used modular by kdb */
static inline int valid_stack_ptr(struct thread_info *tinfo, void *p)
{
return p > (void *)tinfo &&
p < (void *)tinfo + THREAD_SIZE - 3;
}
static inline unsigned long print_context_stack(struct thread_info *tinfo,
unsigned long *stack, unsigned long ebp,
struct stacktrace_ops *ops, void *data)
{
unsigned long addr;
#ifdef CONFIG_FRAME_POINTER
while (valid_stack_ptr(tinfo, (void *)ebp)) {
unsigned long new_ebp;
addr = *(unsigned long *)(ebp + 4);
ops->address(data, addr);
/*
* break out of recursive entries (such as
* end_of_stack_stop_unwind_function). Also,
* we can never allow a frame pointer to
* move downwards!
*/
new_ebp = *(unsigned long *)ebp;
if (new_ebp <= ebp)
break;
ebp = new_ebp;
}
#else
while (valid_stack_ptr(tinfo, stack)) {
addr = *stack++;
if (__kernel_text_address(addr))
ops->address(data, addr);
}
#endif
return ebp;
}
#define MSG(msg) ops->warning(data, msg)
void dump_trace(struct task_struct *task, struct pt_regs *regs,
unsigned long *stack,
struct stacktrace_ops *ops, void *data)
{
unsigned long ebp = 0;
if (!task)
task = current;
if (!stack) {
unsigned long dummy;
stack = &dummy;
if (task && task != current)
stack = (unsigned long *)task->thread.esp;
}
#ifdef CONFIG_FRAME_POINTER
if (!ebp) {
if (task == current) {
/* Grab ebp right from our regs */
asm ("movl %%ebp, %0" : "=r" (ebp) : );
} else {
/* ebp is the last reg pushed by switch_to */
ebp = *(unsigned long *) task->thread.esp;
}
}
#endif
while (1) {
struct thread_info *context;
context = (struct thread_info *)
((unsigned long)stack & (~(THREAD_SIZE - 1)));
ebp = print_context_stack(context, stack, ebp, ops, data);
/* Should be after the line below, but somewhere
in early boot context comes out corrupted and we
can't reference it -AK */
if (ops->stack(data, "IRQ") < 0)
break;
stack = (unsigned long*)context->previous_esp;
if (!stack)
break;
touch_nmi_watchdog();
}
}
EXPORT_SYMBOL(dump_trace);
static void
print_trace_warning_symbol(void *data, char *msg, unsigned long symbol)
{
printk(data);
print_symbol(msg, symbol);
printk("\n");
}
static void print_trace_warning(void *data, char *msg)
{
printk("%s%s\n", (char *)data, msg);
}
static int print_trace_stack(void *data, char *name)
{
return 0;
}
/*
* Print one address/symbol entries per line.
*/
static void print_trace_address(void *data, unsigned long addr)
{
printk("%s [<%08lx>] ", (char *)data, addr);
print_symbol("%s\n", addr);
}
static struct stacktrace_ops print_trace_ops = {
.warning = print_trace_warning,
.warning_symbol = print_trace_warning_symbol,
.stack = print_trace_stack,
.address = print_trace_address,
};
static void
show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
unsigned long * stack, char *log_lvl)
{
dump_trace(task, regs, stack, &print_trace_ops, log_lvl);
printk("%s =======================\n", log_lvl);
}
void show_trace(struct task_struct *task, struct pt_regs *regs,
unsigned long * stack)
{
show_trace_log_lvl(task, regs, stack, "");
}
static void show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
unsigned long *esp, char *log_lvl)
{
unsigned long *stack;
int i;
if (esp == NULL) {
if (task)
esp = (unsigned long*)task->thread.esp;
else
esp = (unsigned long *)&esp;
}
stack = esp;
for(i = 0; i < kstack_depth_to_print; i++) {
if (kstack_end(stack))
break;
if (i && ((i % 8) == 0))
printk("\n%s ", log_lvl);
printk("%08lx ", *stack++);
}
printk("\n%sCall Trace:\n", log_lvl);
show_trace_log_lvl(task, regs, esp, log_lvl);
}
void show_stack(struct task_struct *task, unsigned long *esp)
{
printk(" ");
show_stack_log_lvl(task, NULL, esp, "");
}
/*
* The architecture-independent dump_stack generator
*/
void dump_stack(void)
{
unsigned long stack;
show_trace(current, NULL, &stack);
}
EXPORT_SYMBOL(dump_stack);
void show_registers(struct pt_regs *regs)
{
int i;
int in_kernel = 1;
unsigned long esp;
unsigned short ss, gs;
esp = (unsigned long) (&regs->esp);
savesegment(ss, ss);
savesegment(gs, gs);
if (user_mode_vm(regs)) {
in_kernel = 0;
esp = regs->esp;
ss = regs->xss & 0xffff;
}
print_modules();
printk(KERN_EMERG "CPU: %d\n"
KERN_EMERG "EIP: %04x:[<%08lx>] %s VLI\n"
KERN_EMERG "EFLAGS: %08lx (%s %.*s)\n",
smp_processor_id(), 0xffff & regs->xcs, regs->eip,
print_tainted(), regs->eflags, init_utsname()->release,
(int)strcspn(init_utsname()->version, " "),
init_utsname()->version);
print_symbol(KERN_EMERG "EIP is at %s\n", regs->eip);
printk(KERN_EMERG "eax: %08lx ebx: %08lx ecx: %08lx edx: %08lx\n",
regs->eax, regs->ebx, regs->ecx, regs->edx);
printk(KERN_EMERG "esi: %08lx edi: %08lx ebp: %08lx esp: %08lx\n",
regs->esi, regs->edi, regs->ebp, esp);
printk(KERN_EMERG "ds: %04x es: %04x fs: %04x gs: %04x ss: %04x\n",
regs->xds & 0xffff, regs->xes & 0xffff, regs->xfs & 0xffff, gs, ss);
printk(KERN_EMERG "Process %.*s (pid: %d, ti=%p task=%p task.ti=%p)",
TASK_COMM_LEN, current->comm, current->pid,
current_thread_info(), current, current->thread_info);
/*
* When in-kernel, we also print out the stack and code at the
* time of the fault..
*/
if (in_kernel) {
u8 *eip;
unsigned int code_prologue = code_bytes * 43 / 64;
unsigned int code_len = code_bytes;
unsigned char c;
printk("\n" KERN_EMERG "Stack: ");
show_stack_log_lvl(NULL, regs, (unsigned long *)esp, KERN_EMERG);
printk(KERN_EMERG "Code: ");
eip = (u8 *)regs->eip - code_prologue;
if (eip < (u8 *)PAGE_OFFSET ||
probe_kernel_address(eip, c)) {
/* try starting at EIP */
eip = (u8 *)regs->eip;
code_len = code_len - code_prologue + 1;
}
for (i = 0; i < code_len; i++, eip++) {
if (eip < (u8 *)PAGE_OFFSET ||
probe_kernel_address(eip, c)) {
printk(" Bad EIP value.");
break;
}
if (eip == (u8 *)regs->eip)
printk("<%02x> ", c);
else
printk("%02x ", c);
}
}
printk("\n");
}
int is_valid_bugaddr(unsigned long eip)
{
unsigned short ud2;
if (eip < PAGE_OFFSET)
return 0;
if (probe_kernel_address((unsigned short *)eip, ud2))
return 0;
return ud2 == 0x0b0f;
}
/*
* This is gone through when something in the kernel has done something bad and
* is about to be terminated.
*/
void die(const char * str, struct pt_regs * regs, long err)
{
static struct {
spinlock_t lock;
u32 lock_owner;
int lock_owner_depth;
} die = {
.lock = __SPIN_LOCK_UNLOCKED(die.lock),
.lock_owner = -1,
.lock_owner_depth = 0
};
static int die_counter;
unsigned long flags;
oops_enter();
if (die.lock_owner != raw_smp_processor_id()) {
console_verbose();
spin_lock_irqsave(&die.lock, flags);
die.lock_owner = smp_processor_id();
die.lock_owner_depth = 0;
bust_spinlocks(1);
}
else
local_save_flags(flags);
if (++die.lock_owner_depth < 3) {
int nl = 0;
unsigned long esp;
unsigned short ss;
report_bug(regs->eip);
printk(KERN_EMERG "%s: %04lx [#%d]\n", str, err & 0xffff, ++die_counter);
#ifdef CONFIG_PREEMPT
printk(KERN_EMERG "PREEMPT ");
nl = 1;
#endif
#ifdef CONFIG_SMP
if (!nl)
printk(KERN_EMERG);
printk("SMP ");
nl = 1;
#endif
#ifdef CONFIG_DEBUG_PAGEALLOC
if (!nl)
printk(KERN_EMERG);
printk("DEBUG_PAGEALLOC");
nl = 1;
#endif
if (nl)
printk("\n");
if (notify_die(DIE_OOPS, str, regs, err,
current->thread.trap_no, SIGSEGV) !=
NOTIFY_STOP) {
show_registers(regs);
/* Executive summary in case the oops scrolled away */
esp = (unsigned long) (&regs->esp);
savesegment(ss, ss);
if (user_mode(regs)) {
esp = regs->esp;
ss = regs->xss & 0xffff;
}
printk(KERN_EMERG "EIP: [<%08lx>] ", regs->eip);
print_symbol("%s", regs->eip);
printk(" SS:ESP %04x:%08lx\n", ss, esp);
}
else
regs = NULL;
} else
printk(KERN_EMERG "Recursive die() failure, output suppressed\n");
bust_spinlocks(0);
die.lock_owner = -1;
spin_unlock_irqrestore(&die.lock, flags);
if (!regs)
return;
if (kexec_should_crash(current))
crash_kexec(regs);
if (in_interrupt())
panic("Fatal exception in interrupt");
if (panic_on_oops)
panic("Fatal exception");
oops_exit();
do_exit(SIGSEGV);
}
static inline void die_if_kernel(const char * str, struct pt_regs * regs, long err)
{
if (!user_mode_vm(regs))
die(str, regs, err);
}
static void __kprobes do_trap(int trapnr, int signr, char *str, int vm86,
struct pt_regs * regs, long error_code,
siginfo_t *info)
{
struct task_struct *tsk = current;
if (regs->eflags & VM_MASK) {
if (vm86)
goto vm86_trap;
goto trap_signal;
}
if (!user_mode(regs))
goto kernel_trap;
trap_signal: {
/*
* We want error_code and trap_no set for userspace faults and
* kernelspace faults which result in die(), but not
* kernelspace faults which are fixed up. die() gives the
* process no chance to handle the signal and notice the
* kernel fault information, so that won't result in polluting
* the information about previously queued, but not yet
* delivered, faults. See also do_general_protection below.
*/
tsk->thread.error_code = error_code;
tsk->thread.trap_no = trapnr;
if (info)
force_sig_info(signr, info, tsk);
else
force_sig(signr, tsk);
return;
}
kernel_trap: {
if (!fixup_exception(regs)) {
tsk->thread.error_code = error_code;
tsk->thread.trap_no = trapnr;
die(str, regs, error_code);
}
return;
}
vm86_trap: {
int ret = handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code, trapnr);
if (ret) goto trap_signal;
return;
}
}
#define DO_ERROR(trapnr, signr, str, name) \
fastcall void do_##name(struct pt_regs * regs, long error_code) \
{ \
if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
== NOTIFY_STOP) \
return; \
do_trap(trapnr, signr, str, 0, regs, error_code, NULL); \
}
#define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr) \
fastcall void do_##name(struct pt_regs * regs, long error_code) \
{ \
siginfo_t info; \
info.si_signo = signr; \
info.si_errno = 0; \
info.si_code = sicode; \
info.si_addr = (void __user *)siaddr; \
if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
== NOTIFY_STOP) \
return; \
do_trap(trapnr, signr, str, 0, regs, error_code, &info); \
}
#define DO_VM86_ERROR(trapnr, signr, str, name) \
fastcall void do_##name(struct pt_regs * regs, long error_code) \
{ \
if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
== NOTIFY_STOP) \
return; \
do_trap(trapnr, signr, str, 1, regs, error_code, NULL); \
}
#define DO_VM86_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr) \
fastcall void do_##name(struct pt_regs * regs, long error_code) \
{ \
siginfo_t info; \
info.si_signo = signr; \
info.si_errno = 0; \
info.si_code = sicode; \
info.si_addr = (void __user *)siaddr; \
if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
== NOTIFY_STOP) \
return; \
do_trap(trapnr, signr, str, 1, regs, error_code, &info); \
}
DO_VM86_ERROR_INFO( 0, SIGFPE, "divide error", divide_error, FPE_INTDIV, regs->eip)
#ifndef CONFIG_KPROBES
DO_VM86_ERROR( 3, SIGTRAP, "int3", int3)
#endif
DO_VM86_ERROR( 4, SIGSEGV, "overflow", overflow)
DO_VM86_ERROR( 5, SIGSEGV, "bounds", bounds)
DO_ERROR_INFO( 6, SIGILL, "invalid opcode", invalid_op, ILL_ILLOPN, regs->eip)
DO_ERROR( 9, SIGFPE, "coprocessor segment overrun", coprocessor_segment_overrun)
DO_ERROR(10, SIGSEGV, "invalid TSS", invalid_TSS)
DO_ERROR(11, SIGBUS, "segment not present", segment_not_present)
DO_ERROR(12, SIGBUS, "stack segment", stack_segment)
DO_ERROR_INFO(17, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0)
DO_ERROR_INFO(32, SIGSEGV, "iret exception", iret_error, ILL_BADSTK, 0)
fastcall void __kprobes do_general_protection(struct pt_regs * regs,
long error_code)
{
int cpu = get_cpu();
struct tss_struct *tss = &per_cpu(init_tss, cpu);
struct thread_struct *thread = &current->thread;
/*
* Perform the lazy TSS's I/O bitmap copy. If the TSS has an
* invalid offset set (the LAZY one) and the faulting thread has
* a valid I/O bitmap pointer, we copy the I/O bitmap in the TSS
* and we set the offset field correctly. Then we let the CPU to
* restart the faulting instruction.
*/
if (tss->io_bitmap_base == INVALID_IO_BITMAP_OFFSET_LAZY &&
thread->io_bitmap_ptr) {
memcpy(tss->io_bitmap, thread->io_bitmap_ptr,
thread->io_bitmap_max);
/*
* If the previously set map was extending to higher ports
* than the current one, pad extra space with 0xff (no access).
*/
if (thread->io_bitmap_max < tss->io_bitmap_max)
memset((char *) tss->io_bitmap +
thread->io_bitmap_max, 0xff,
tss->io_bitmap_max - thread->io_bitmap_max);
tss->io_bitmap_max = thread->io_bitmap_max;
tss->io_bitmap_base = IO_BITMAP_OFFSET;
tss->io_bitmap_owner = thread;
put_cpu();
return;
}
put_cpu();
if (regs->eflags & VM_MASK)
goto gp_in_vm86;
if (!user_mode(regs))
goto gp_in_kernel;
current->thread.error_code = error_code;
current->thread.trap_no = 13;
force_sig(SIGSEGV, current);
return;
gp_in_vm86:
local_irq_enable();
handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
return;
gp_in_kernel:
if (!fixup_exception(regs)) {
current->thread.error_code = error_code;
current->thread.trap_no = 13;
if (notify_die(DIE_GPF, "general protection fault", regs,
error_code, 13, SIGSEGV) == NOTIFY_STOP)
return;
die("general protection fault", regs, error_code);
}
}
static __kprobes void
mem_parity_error(unsigned char reason, struct pt_regs * regs)
{
printk(KERN_EMERG "Uhhuh. NMI received for unknown reason %02x on "
"CPU %d.\n", reason, smp_processor_id());
printk(KERN_EMERG "You have some hardware problem, likely on the PCI bus.\n");
if (panic_on_unrecovered_nmi)
panic("NMI: Not continuing");
printk(KERN_EMERG "Dazed and confused, but trying to continue\n");
/* Clear and disable the memory parity error line. */
clear_mem_error(reason);
}
static __kprobes void
io_check_error(unsigned char reason, struct pt_regs * regs)
{
unsigned long i;
printk(KERN_EMERG "NMI: IOCK error (debug interrupt?)\n");
show_registers(regs);
/* Re-enable the IOCK line, wait for a few seconds */
reason = (reason & 0xf) | 8;
outb(reason, 0x61);
i = 2000;
while (--i) udelay(1000);
reason &= ~8;
outb(reason, 0x61);
}
static __kprobes void
unknown_nmi_error(unsigned char reason, struct pt_regs * regs)
{
#ifdef CONFIG_MCA
/* Might actually be able to figure out what the guilty party
* is. */
if( MCA_bus ) {
mca_handle_nmi();
return;
}
#endif
printk(KERN_EMERG "Uhhuh. NMI received for unknown reason %02x on "
"CPU %d.\n", reason, smp_processor_id());
printk(KERN_EMERG "Do you have a strange power saving mode enabled?\n");
if (panic_on_unrecovered_nmi)
panic("NMI: Not continuing");
printk(KERN_EMERG "Dazed and confused, but trying to continue\n");
}
static DEFINE_SPINLOCK(nmi_print_lock);
void __kprobes die_nmi(struct pt_regs *regs, const char *msg)
{
if (notify_die(DIE_NMIWATCHDOG, msg, regs, 0, 2, SIGINT) ==
NOTIFY_STOP)
return;
spin_lock(&nmi_print_lock);
/*
* We are in trouble anyway, lets at least try
* to get a message out.
*/
bust_spinlocks(1);
printk(KERN_EMERG "%s", msg);
printk(" on CPU%d, eip %08lx, registers:\n",
smp_processor_id(), regs->eip);
show_registers(regs);
console_silent();
spin_unlock(&nmi_print_lock);
bust_spinlocks(0);
/* If we are in kernel we are probably nested up pretty bad
* and might aswell get out now while we still can.
*/
if (!user_mode_vm(regs)) {
current->thread.trap_no = 2;
crash_kexec(regs);
}
do_exit(SIGSEGV);
}
static __kprobes void default_do_nmi(struct pt_regs * regs)
{
unsigned char reason = 0;
/* Only the BSP gets external NMIs from the system. */
if (!smp_processor_id())
reason = get_nmi_reason();
if (!(reason & 0xc0)) {
if (notify_die(DIE_NMI_IPI, "nmi_ipi", regs, reason, 2, SIGINT)
== NOTIFY_STOP)
return;
#ifdef CONFIG_X86_LOCAL_APIC
/*
* Ok, so this is none of the documented NMI sources,
* so it must be the NMI watchdog.
*/
if (nmi_watchdog_tick(regs, reason))
return;
if (!do_nmi_callback(regs, smp_processor_id()))
#endif
unknown_nmi_error(reason, regs);
return;
}
if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT) == NOTIFY_STOP)
return;
if (reason & 0x80)
mem_parity_error(reason, regs);
if (reason & 0x40)
io_check_error(reason, regs);
/*
* Reassert NMI in case it became active meanwhile
* as it's edge-triggered.
*/
reassert_nmi();
}
fastcall __kprobes void do_nmi(struct pt_regs * regs, long error_code)
{
int cpu;
nmi_enter();
cpu = smp_processor_id();
++nmi_count(cpu);
default_do_nmi(regs);
nmi_exit();
}
#ifdef CONFIG_KPROBES
fastcall void __kprobes do_int3(struct pt_regs *regs, long error_code)
{
if (notify_die(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP)
== NOTIFY_STOP)
return;
/* This is an interrupt gate, because kprobes wants interrupts
disabled. Normal trap handlers don't. */
restore_interrupts(regs);
do_trap(3, SIGTRAP, "int3", 1, regs, error_code, NULL);
}
#endif
/*
* Our handling of the processor debug registers is non-trivial.
* We do not clear them on entry and exit from the kernel. Therefore
* it is possible to get a watchpoint trap here from inside the kernel.
* However, the code in ./ptrace.c has ensured that the user can
* only set watchpoints on userspace addresses. Therefore the in-kernel
* watchpoint trap can only occur in code which is reading/writing
* from user space. Such code must not hold kernel locks (since it
* can equally take a page fault), therefore it is safe to call
* force_sig_info even though that claims and releases locks.
*
* Code in ./signal.c ensures that the debug control register
* is restored before we deliver any signal, and therefore that
* user code runs with the correct debug control register even though
* we clear it here.
*
* Being careful here means that we don't have to be as careful in a
* lot of more complicated places (task switching can be a bit lazy
* about restoring all the debug state, and ptrace doesn't have to
* find every occurrence of the TF bit that could be saved away even
* by user code)
*/
fastcall void __kprobes do_debug(struct pt_regs * regs, long error_code)
{
unsigned int condition;
struct task_struct *tsk = current;
get_debugreg(condition, 6);
if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code,
SIGTRAP) == NOTIFY_STOP)
return;
/* It's safe to allow irq's after DR6 has been saved */
if (regs->eflags & X86_EFLAGS_IF)
local_irq_enable();
/* Mask out spurious debug traps due to lazy DR7 setting */
if (condition & (DR_TRAP0|DR_TRAP1|DR_TRAP2|DR_TRAP3)) {
if (!tsk->thread.debugreg[7])
goto clear_dr7;
}
if (regs->eflags & VM_MASK)
goto debug_vm86;
/* Save debug status register where ptrace can see it */
tsk->thread.debugreg[6] = condition;
/*
* Single-stepping through TF: make sure we ignore any events in
* kernel space (but re-enable TF when returning to user mode).
*/
if (condition & DR_STEP) {
/*
* We already checked v86 mode above, so we can
* check for kernel mode by just checking the CPL
* of CS.
*/
if (!user_mode(regs))
goto clear_TF_reenable;
}
/* Ok, finally something we can handle */
send_sigtrap(tsk, regs, error_code);
/* Disable additional traps. They'll be re-enabled when
* the signal is delivered.
*/
clear_dr7:
set_debugreg(0, 7);
return;
debug_vm86:
handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code, 1);
return;
clear_TF_reenable:
set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
regs->eflags &= ~TF_MASK;
return;
}
/*
* Note that we play around with the 'TS' bit in an attempt to get
* the correct behaviour even in the presence of the asynchronous
* IRQ13 behaviour
*/
void math_error(void __user *eip)
{
struct task_struct * task;
siginfo_t info;
unsigned short cwd, swd;
/*
* Save the info for the exception handler and clear the error.
*/
task = current;
save_init_fpu(task);
task->thread.trap_no = 16;
task->thread.error_code = 0;
info.si_signo = SIGFPE;
info.si_errno = 0;
info.si_code = __SI_FAULT;
info.si_addr = eip;
/*
* (~cwd & swd) will mask out exceptions that are not set to unmasked
* status. 0x3f is the exception bits in these regs, 0x200 is the
* C1 reg you need in case of a stack fault, 0x040 is the stack
* fault bit. We should only be taking one exception at a time,
* so if this combination doesn't produce any single exception,
* then we have a bad program that isn't syncronizing its FPU usage
* and it will suffer the consequences since we won't be able to
* fully reproduce the context of the exception
*/
cwd = get_fpu_cwd(task);
swd = get_fpu_swd(task);
switch (swd & ~cwd & 0x3f) {
case 0x000: /* No unmasked exception */
return;
default: /* Multiple exceptions */
break;
case 0x001: /* Invalid Op */
/*
* swd & 0x240 == 0x040: Stack Underflow
* swd & 0x240 == 0x240: Stack Overflow
* User must clear the SF bit (0x40) if set
*/
info.si_code = FPE_FLTINV;
break;
case 0x002: /* Denormalize */
case 0x010: /* Underflow */
info.si_code = FPE_FLTUND;
break;
case 0x004: /* Zero Divide */
info.si_code = FPE_FLTDIV;
break;
case 0x008: /* Overflow */
info.si_code = FPE_FLTOVF;
break;
case 0x020: /* Precision */
info.si_code = FPE_FLTRES;
break;
}
force_sig_info(SIGFPE, &info, task);
}
fastcall void do_coprocessor_error(struct pt_regs * regs, long error_code)
{
ignore_fpu_irq = 1;
math_error((void __user *)regs->eip);
}
static void simd_math_error(void __user *eip)
{
struct task_struct * task;
siginfo_t info;
unsigned short mxcsr;
/*
* Save the info for the exception handler and clear the error.
*/
task = current;
save_init_fpu(task);
task->thread.trap_no = 19;
task->thread.error_code = 0;
info.si_signo = SIGFPE;
info.si_errno = 0;
info.si_code = __SI_FAULT;
info.si_addr = eip;
/*
* The SIMD FPU exceptions are handled a little differently, as there
* is only a single status/control register. Thus, to determine which
* unmasked exception was caught we must mask the exception mask bits
* at 0x1f80, and then use these to mask the exception bits at 0x3f.
*/
mxcsr = get_fpu_mxcsr(task);
switch (~((mxcsr & 0x1f80) >> 7) & (mxcsr & 0x3f)) {
case 0x000:
default:
break;
case 0x001: /* Invalid Op */
info.si_code = FPE_FLTINV;
break;
case 0x002: /* Denormalize */
case 0x010: /* Underflow */
info.si_code = FPE_FLTUND;
break;
case 0x004: /* Zero Divide */
info.si_code = FPE_FLTDIV;
break;
case 0x008: /* Overflow */
info.si_code = FPE_FLTOVF;
break;
case 0x020: /* Precision */
info.si_code = FPE_FLTRES;
break;
}
force_sig_info(SIGFPE, &info, task);
}
fastcall void do_simd_coprocessor_error(struct pt_regs * regs,
long error_code)
{
if (cpu_has_xmm) {
/* Handle SIMD FPU exceptions on PIII+ processors. */
ignore_fpu_irq = 1;
simd_math_error((void __user *)regs->eip);
} else {
/*
* Handle strange cache flush from user space exception
* in all other cases. This is undocumented behaviour.
*/
if (regs->eflags & VM_MASK) {
handle_vm86_fault((struct kernel_vm86_regs *)regs,
error_code);
return;
}
current->thread.trap_no = 19;
current->thread.error_code = error_code;
die_if_kernel("cache flush denied", regs, error_code);
force_sig(SIGSEGV, current);
}
}
fastcall void do_spurious_interrupt_bug(struct pt_regs * regs,
long error_code)
{
#if 0
/* No need to warn about this any longer. */
printk("Ignoring P6 Local APIC Spurious Interrupt Bug...\n");
#endif
}
fastcall unsigned long patch_espfix_desc(unsigned long uesp,
unsigned long kesp)
{
int cpu = smp_processor_id();
struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu);
struct desc_struct *gdt = (struct desc_struct *)cpu_gdt_descr->address;
unsigned long base = (kesp - uesp) & -THREAD_SIZE;
unsigned long new_kesp = kesp - base;
unsigned long lim_pages = (new_kesp | (THREAD_SIZE - 1)) >> PAGE_SHIFT;
__u64 desc = *(__u64 *)&gdt[GDT_ENTRY_ESPFIX_SS];
/* Set up base for espfix segment */
desc &= 0x00f0ff0000000000ULL;
desc |= ((((__u64)base) << 16) & 0x000000ffffff0000ULL) |
((((__u64)base) << 32) & 0xff00000000000000ULL) |
((((__u64)lim_pages) << 32) & 0x000f000000000000ULL) |
(lim_pages & 0xffff);
*(__u64 *)&gdt[GDT_ENTRY_ESPFIX_SS] = desc;
return new_kesp;
}
/*
* 'math_state_restore()' saves the current math information in the
* old math state array, and gets the new ones from the current task
*
* Careful.. There are problems with IBM-designed IRQ13 behaviour.
* Don't touch unless you *really* know how it works.
*
* Must be called with kernel preemption disabled (in this case,
* local interrupts are disabled at the call-site in entry.S).
*/
asmlinkage void math_state_restore(void)
{
struct thread_info *thread = current_thread_info();
struct task_struct *tsk = thread->task;
clts(); /* Allow maths ops (or we recurse) */
if (!tsk_used_math(tsk))
init_fpu(tsk);
restore_fpu(tsk);
thread->status |= TS_USEDFPU; /* So we fnsave on switch_to() */
tsk->fpu_counter++;
}
#ifndef CONFIG_MATH_EMULATION
asmlinkage void math_emulate(long arg)
{
printk(KERN_EMERG "math-emulation not enabled and no coprocessor found.\n");
printk(KERN_EMERG "killing %s.\n",current->comm);
force_sig(SIGFPE,current);
schedule();
}
#endif /* CONFIG_MATH_EMULATION */
#ifdef CONFIG_X86_F00F_BUG
void __init trap_init_f00f_bug(void)
{
__set_fixmap(FIX_F00F_IDT, __pa(&idt_table), PAGE_KERNEL_RO);
/*
* Update the IDT descriptor and reload the IDT so that
* it uses the read-only mapped virtual address.
*/
idt_descr.address = fix_to_virt(FIX_F00F_IDT);
load_idt(&idt_descr);
}
#endif
/*
* This needs to use 'idt_table' rather than 'idt', and
* thus use the _nonmapped_ version of the IDT, as the
* Pentium F0 0F bugfix can have resulted in the mapped
* IDT being write-protected.
*/
void set_intr_gate(unsigned int n, void *addr)
{
_set_gate(n, DESCTYPE_INT, addr, __KERNEL_CS);
}
/*
* This routine sets up an interrupt gate at directory privilege level 3.
*/
static inline void set_system_intr_gate(unsigned int n, void *addr)
{
_set_gate(n, DESCTYPE_INT | DESCTYPE_DPL3, addr, __KERNEL_CS);
}
static void __init set_trap_gate(unsigned int n, void *addr)
{
_set_gate(n, DESCTYPE_TRAP, addr, __KERNEL_CS);
}
static void __init set_system_gate(unsigned int n, void *addr)
{
_set_gate(n, DESCTYPE_TRAP | DESCTYPE_DPL3, addr, __KERNEL_CS);
}
static void __init set_task_gate(unsigned int n, unsigned int gdt_entry)
{
_set_gate(n, DESCTYPE_TASK, (void *)0, (gdt_entry<<3));
}
void __init trap_init(void)
{
#ifdef CONFIG_EISA
void __iomem *p = ioremap(0x0FFFD9, 4);
if (readl(p) == 'E'+('I'<<8)+('S'<<16)+('A'<<24)) {
EISA_bus = 1;
}
iounmap(p);
#endif
#ifdef CONFIG_X86_LOCAL_APIC
init_apic_mappings();
#endif
set_trap_gate(0,&divide_error);
set_intr_gate(1,&debug);
set_intr_gate(2,&nmi);
set_system_intr_gate(3, &int3); /* int3/4 can be called from all */
set_system_gate(4,&overflow);
set_trap_gate(5,&bounds);
set_trap_gate(6,&invalid_op);
set_trap_gate(7,&device_not_available);
set_task_gate(8,GDT_ENTRY_DOUBLEFAULT_TSS);
set_trap_gate(9,&coprocessor_segment_overrun);
set_trap_gate(10,&invalid_TSS);
set_trap_gate(11,&segment_not_present);
set_trap_gate(12,&stack_segment);
set_trap_gate(13,&general_protection);
set_intr_gate(14,&page_fault);
set_trap_gate(15,&spurious_interrupt_bug);
set_trap_gate(16,&coprocessor_error);
set_trap_gate(17,&alignment_check);
#ifdef CONFIG_X86_MCE
set_trap_gate(18,&machine_check);
#endif
set_trap_gate(19,&simd_coprocessor_error);
if (cpu_has_fxsr) {
/*
* Verify that the FXSAVE/FXRSTOR data will be 16-byte aligned.
* Generates a compile-time "error: zero width for bit-field" if
* the alignment is wrong.
*/
struct fxsrAlignAssert {
int _:!(offsetof(struct task_struct,
thread.i387.fxsave) & 15);
};
printk(KERN_INFO "Enabling fast FPU save and restore... ");
set_in_cr4(X86_CR4_OSFXSR);
printk("done.\n");
}
if (cpu_has_xmm) {
printk(KERN_INFO "Enabling unmasked SIMD FPU exception "
"support... ");
set_in_cr4(X86_CR4_OSXMMEXCPT);
printk("done.\n");
}
set_system_gate(SYSCALL_VECTOR,&system_call);
/*
* Should be a barrier for any external CPU state.
*/
cpu_init();
trap_init_hook();
}
static int __init kstack_setup(char *s)
{
kstack_depth_to_print = simple_strtoul(s, NULL, 0);
return 1;
}
__setup("kstack=", kstack_setup);
static int __init code_bytes_setup(char *s)
{
code_bytes = simple_strtoul(s, NULL, 0);
if (code_bytes > 8192)
code_bytes = 8192;
return 1;
}
__setup("code_bytes=", code_bytes_setup);
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