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android_kernel_motorola_sm6225/arch/i386/kernel/traps.c
Jeremy Fitzhardinge 464d1a78fb [PATCH] i386: Convert i386 PDA code to use %fs 
Convert the PDA code to use %fs rather than %gs as the segment for
per-processor data.  This is because some processors show a small but
measurable performance gain for reloading a NULL segment selector (as %fs
generally is in user-space) versus a non-NULL one (as %gs generally is).

On modern processors the difference is very small, perhaps undetectable.
Some old AMD "K6 3D+" processors are noticably slower when %fs is used
rather than %gs; I have no idea why this might be, but I think they're
sufficiently rare that it doesn't matter much.

This patch also fixes the math emulator, which had not been adjusted to
match the changed struct pt_regs.

[frederik.deweerdt@gmail.com: fixit with gdb]
[mingo@elte.hu: Fix KVM too]

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Ian Campbell <Ian.Campbell@XenSource.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Zachary Amsden <zach@vmware.com>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Frederik Deweerdt <frederik.deweerdt@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
2007-02-13 13:26:20 +01:00

1194 lines
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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;
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;
int code_bytes = 64;
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 - 43;
if (eip < (u8 *)PAGE_OFFSET ||
probe_kernel_address(eip, c)) {
/* try starting at EIP */
eip = (u8 *)regs->eip;
code_bytes = 32;
}
for (i = 0; i < code_bytes; 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;
tsk->thread.error_code = error_code;
tsk->thread.trap_no = trapnr;
if (regs->eflags & VM_MASK) {
if (vm86)
goto vm86_trap;
goto trap_signal;
}
if (!user_mode(regs))
goto kernel_trap;
trap_signal: {
if (info)
force_sig_info(signr, info, tsk);
else
force_sig(signr, tsk);
return;
}
kernel_trap: {
if (!fixup_exception(regs))
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();
current->thread.error_code = error_code;
current->thread.trap_no = 13;
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)) {
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);
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