Contributors: 54
| Author |
Tokens |
Token Proportion |
Commits |
Commit Proportion |
| Andrew Lutomirski |
742 |
24.26% |
30 |
14.93% |
| Alexander van Heukelum |
355 |
11.61% |
19 |
9.45% |
| Linus Torvalds (pre-git) |
302 |
9.87% |
32 |
15.92% |
| Eric W. Biedermann |
248 |
8.11% |
7 |
3.48% |
| Frédéric Weisbecker |
246 |
8.04% |
6 |
2.99% |
| Dave Hansen |
197 |
6.44% |
6 |
2.99% |
| Peter Zijlstra |
108 |
3.53% |
2 |
1.00% |
| Oleg Nesterov |
97 |
3.17% |
6 |
2.99% |
| K.Prasad |
80 |
2.62% |
3 |
1.49% |
| Brian Gerst |
68 |
2.22% |
5 |
2.49% |
| Prasanna S. Panchamukhi |
66 |
2.16% |
3 |
1.49% |
| Ingo Molnar |
65 |
2.12% |
14 |
6.97% |
| Masami Hiramatsu |
62 |
2.03% |
3 |
1.49% |
| Kees Cook |
42 |
1.37% |
3 |
1.49% |
| Steven Rostedt |
38 |
1.24% |
4 |
1.99% |
| Linus Torvalds |
34 |
1.11% |
5 |
2.49% |
| Jann Horn |
30 |
0.98% |
2 |
1.00% |
| Jason Wessel |
25 |
0.82% |
1 |
0.50% |
| Ricardo Neri |
25 |
0.82% |
1 |
0.50% |
| Thomas Gleixner |
21 |
0.69% |
7 |
3.48% |
| Siarhei Liakh |
20 |
0.65% |
1 |
0.50% |
| Alexander Shishkin |
17 |
0.56% |
1 |
0.50% |
| Tejun Heo |
14 |
0.46% |
1 |
0.50% |
| Alexander Kuleshov |
13 |
0.42% |
1 |
0.50% |
| Borislav Petkov |
12 |
0.39% |
1 |
0.50% |
| Harvey Harrison |
12 |
0.39% |
1 |
0.50% |
| Dave Jiang |
11 |
0.36% |
1 |
0.50% |
| Masoud Asgharifard Sharbiani |
11 |
0.36% |
1 |
0.50% |
| Jiri Kosina |
11 |
0.36% |
1 |
0.50% |
| Alexander Nyberg |
7 |
0.23% |
2 |
1.00% |
| Joe Perches |
7 |
0.23% |
1 |
0.50% |
| Rusty Russell |
6 |
0.20% |
3 |
1.49% |
| Yinghai Lu |
6 |
0.20% |
1 |
0.50% |
| Vincent Hanquez |
6 |
0.20% |
2 |
1.00% |
| H. Peter Anvin |
6 |
0.20% |
3 |
1.49% |
| Tony Luck |
6 |
0.20% |
1 |
0.50% |
| Jan Beulich |
5 |
0.16% |
2 |
1.00% |
| Srikar Dronamraju |
4 |
0.13% |
1 |
0.50% |
| Bart Oldeman |
4 |
0.13% |
1 |
0.50% |
| Hidetoshi Seto |
3 |
0.10% |
1 |
0.50% |
| Jeremy Fitzhardinge |
3 |
0.10% |
1 |
0.50% |
| Srinivasa D S |
3 |
0.10% |
1 |
0.50% |
| Andi Kleen |
3 |
0.10% |
2 |
1.00% |
| Jamie Lokier |
3 |
0.10% |
1 |
0.50% |
| Paul E. McKenney |
2 |
0.07% |
1 |
0.50% |
| Daniel Jacobowitz |
2 |
0.07% |
1 |
0.50% |
| Rasmus Villemoes |
2 |
0.07% |
1 |
0.50% |
| Andrew Morton |
2 |
0.07% |
1 |
0.50% |
| Dave Jones |
2 |
0.07% |
1 |
0.50% |
| Chuck Ebbert |
1 |
0.03% |
1 |
0.50% |
| Paul Gortmaker |
1 |
0.03% |
1 |
0.50% |
| Stas Sergeev |
1 |
0.03% |
1 |
0.50% |
| Wang Nan |
1 |
0.03% |
1 |
0.50% |
| Arun Sharma |
1 |
0.03% |
1 |
0.50% |
| Total |
3059 |
|
201 |
|
/*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
*
* Pentium III FXSR, SSE support
* Gareth Hughes <gareth@valinux.com>, May 2000
*/
/*
* Handle hardware traps and faults.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/context_tracking.h>
#include <linux/interrupt.h>
#include <linux/kallsyms.h>
#include <linux/spinlock.h>
#include <linux/kprobes.h>
#include <linux/uaccess.h>
#include <linux/kdebug.h>
#include <linux/kgdb.h>
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/ptrace.h>
#include <linux/uprobes.h>
#include <linux/string.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/kexec.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/timer.h>
#include <linux/init.h>
#include <linux/bug.h>
#include <linux/nmi.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/io.h>
#if defined(CONFIG_EDAC)
#include <linux/edac.h>
#endif
#include <asm/stacktrace.h>
#include <asm/processor.h>
#include <asm/debugreg.h>
#include <linux/atomic.h>
#include <asm/text-patching.h>
#include <asm/ftrace.h>
#include <asm/traps.h>
#include <asm/desc.h>
#include <asm/fpu/internal.h>
#include <asm/cpu_entry_area.h>
#include <asm/mce.h>
#include <asm/fixmap.h>
#include <asm/mach_traps.h>
#include <asm/alternative.h>
#include <asm/fpu/xstate.h>
#include <asm/trace/mpx.h>
#include <asm/mpx.h>
#include <asm/vm86.h>
#include <asm/umip.h>
#ifdef CONFIG_X86_64
#include <asm/x86_init.h>
#include <asm/pgalloc.h>
#include <asm/proto.h>
#else
#include <asm/processor-flags.h>
#include <asm/setup.h>
#include <asm/proto.h>
#endif
DECLARE_BITMAP(system_vectors, NR_VECTORS);
static inline void cond_local_irq_enable(struct pt_regs *regs)
{
if (regs->flags & X86_EFLAGS_IF)
local_irq_enable();
}
static inline void cond_local_irq_disable(struct pt_regs *regs)
{
if (regs->flags & X86_EFLAGS_IF)
local_irq_disable();
}
/*
* In IST context, we explicitly disable preemption. This serves two
* purposes: it makes it much less likely that we would accidentally
* schedule in IST context and it will force a warning if we somehow
* manage to schedule by accident.
*/
void ist_enter(struct pt_regs *regs)
{
if (user_mode(regs)) {
RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
} else {
/*
* We might have interrupted pretty much anything. In
* fact, if we're a machine check, we can even interrupt
* NMI processing. We don't want in_nmi() to return true,
* but we need to notify RCU.
*/
rcu_nmi_enter();
}
preempt_disable();
/* This code is a bit fragile. Test it. */
RCU_LOCKDEP_WARN(!rcu_is_watching(), "ist_enter didn't work");
}
void ist_exit(struct pt_regs *regs)
{
preempt_enable_no_resched();
if (!user_mode(regs))
rcu_nmi_exit();
}
/**
* ist_begin_non_atomic() - begin a non-atomic section in an IST exception
* @regs: regs passed to the IST exception handler
*
* IST exception handlers normally cannot schedule. As a special
* exception, if the exception interrupted userspace code (i.e.
* user_mode(regs) would return true) and the exception was not
* a double fault, it can be safe to schedule. ist_begin_non_atomic()
* begins a non-atomic section within an ist_enter()/ist_exit() region.
* Callers are responsible for enabling interrupts themselves inside
* the non-atomic section, and callers must call ist_end_non_atomic()
* before ist_exit().
*/
void ist_begin_non_atomic(struct pt_regs *regs)
{
BUG_ON(!user_mode(regs));
/*
* Sanity check: we need to be on the normal thread stack. This
* will catch asm bugs and any attempt to use ist_preempt_enable
* from double_fault.
*/
BUG_ON(!on_thread_stack());
preempt_enable_no_resched();
}
/**
* ist_end_non_atomic() - begin a non-atomic section in an IST exception
*
* Ends a non-atomic section started with ist_begin_non_atomic().
*/
void ist_end_non_atomic(void)
{
preempt_disable();
}
int is_valid_bugaddr(unsigned long addr)
{
unsigned short ud;
if (addr < TASK_SIZE_MAX)
return 0;
if (probe_kernel_address((unsigned short *)addr, ud))
return 0;
return ud == INSN_UD0 || ud == INSN_UD2;
}
int fixup_bug(struct pt_regs *regs, int trapnr)
{
if (trapnr != X86_TRAP_UD)
return 0;
switch (report_bug(regs->ip, regs)) {
case BUG_TRAP_TYPE_NONE:
case BUG_TRAP_TYPE_BUG:
break;
case BUG_TRAP_TYPE_WARN:
regs->ip += LEN_UD2;
return 1;
}
return 0;
}
static nokprobe_inline int
do_trap_no_signal(struct task_struct *tsk, int trapnr, const char *str,
struct pt_regs *regs, long error_code)
{
if (v8086_mode(regs)) {
/*
* Traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
* On nmi (interrupt 2), do_trap should not be called.
*/
if (trapnr < X86_TRAP_UD) {
if (!handle_vm86_trap((struct kernel_vm86_regs *) regs,
error_code, trapnr))
return 0;
}
} else if (!user_mode(regs)) {
if (fixup_exception(regs, trapnr, error_code, 0))
return 0;
tsk->thread.error_code = error_code;
tsk->thread.trap_nr = trapnr;
die(str, regs, error_code);
}
/*
* We want error_code and trap_nr 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_nr = trapnr;
return -1;
}
static void show_signal(struct task_struct *tsk, int signr,
const char *type, const char *desc,
struct pt_regs *regs, long error_code)
{
if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
printk_ratelimit()) {
pr_info("%s[%d] %s%s ip:%lx sp:%lx error:%lx",
tsk->comm, task_pid_nr(tsk), type, desc,
regs->ip, regs->sp, error_code);
print_vma_addr(KERN_CONT " in ", regs->ip);
pr_cont("\n");
}
}
static void
do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
long error_code, int sicode, void __user *addr)
{
struct task_struct *tsk = current;
if (!do_trap_no_signal(tsk, trapnr, str, regs, error_code))
return;
show_signal(tsk, signr, "trap ", str, regs, error_code);
if (!sicode)
force_sig(signr, tsk);
else
force_sig_fault(signr, sicode, addr, tsk);
}
NOKPROBE_SYMBOL(do_trap);
static void do_error_trap(struct pt_regs *regs, long error_code, char *str,
unsigned long trapnr, int signr, int sicode, void __user *addr)
{
RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
/*
* WARN*()s end up here; fix them up before we call the
* notifier chain.
*/
if (!user_mode(regs) && fixup_bug(regs, trapnr))
return;
if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) !=
NOTIFY_STOP) {
cond_local_irq_enable(regs);
do_trap(trapnr, signr, str, regs, error_code, sicode, addr);
}
}
#define IP ((void __user *)uprobe_get_trap_addr(regs))
#define DO_ERROR(trapnr, signr, sicode, addr, str, name) \
dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \
{ \
do_error_trap(regs, error_code, str, trapnr, signr, sicode, addr); \
}
DO_ERROR(X86_TRAP_DE, SIGFPE, FPE_INTDIV, IP, "divide error", divide_error)
DO_ERROR(X86_TRAP_OF, SIGSEGV, 0, NULL, "overflow", overflow)
DO_ERROR(X86_TRAP_UD, SIGILL, ILL_ILLOPN, IP, "invalid opcode", invalid_op)
DO_ERROR(X86_TRAP_OLD_MF, SIGFPE, 0, NULL, "coprocessor segment overrun", coprocessor_segment_overrun)
DO_ERROR(X86_TRAP_TS, SIGSEGV, 0, NULL, "invalid TSS", invalid_TSS)
DO_ERROR(X86_TRAP_NP, SIGBUS, 0, NULL, "segment not present", segment_not_present)
DO_ERROR(X86_TRAP_SS, SIGBUS, 0, NULL, "stack segment", stack_segment)
DO_ERROR(X86_TRAP_AC, SIGBUS, BUS_ADRALN, NULL, "alignment check", alignment_check)
#undef IP
#ifdef CONFIG_VMAP_STACK
__visible void __noreturn handle_stack_overflow(const char *message,
struct pt_regs *regs,
unsigned long fault_address)
{
printk(KERN_EMERG "BUG: stack guard page was hit at %p (stack is %p..%p)\n",
(void *)fault_address, current->stack,
(char *)current->stack + THREAD_SIZE - 1);
die(message, regs, 0);
/* Be absolutely certain we don't return. */
panic("%s", message);
}
#endif
#ifdef CONFIG_X86_64
/* Runs on IST stack */
dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
{
static const char str[] = "double fault";
struct task_struct *tsk = current;
#ifdef CONFIG_VMAP_STACK
unsigned long cr2;
#endif
#ifdef CONFIG_X86_ESPFIX64
extern unsigned char native_irq_return_iret[];
/*
* If IRET takes a non-IST fault on the espfix64 stack, then we
* end up promoting it to a doublefault. In that case, take
* advantage of the fact that we're not using the normal (TSS.sp0)
* stack right now. We can write a fake #GP(0) frame at TSS.sp0
* and then modify our own IRET frame so that, when we return,
* we land directly at the #GP(0) vector with the stack already
* set up according to its expectations.
*
* The net result is that our #GP handler will think that we
* entered from usermode with the bad user context.
*
* No need for ist_enter here because we don't use RCU.
*/
if (((long)regs->sp >> P4D_SHIFT) == ESPFIX_PGD_ENTRY &&
regs->cs == __KERNEL_CS &&
regs->ip == (unsigned long)native_irq_return_iret)
{
struct pt_regs *gpregs = (struct pt_regs *)this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1;
/*
* regs->sp points to the failing IRET frame on the
* ESPFIX64 stack. Copy it to the entry stack. This fills
* in gpregs->ss through gpregs->ip.
*
*/
memmove(&gpregs->ip, (void *)regs->sp, 5*8);
gpregs->orig_ax = 0; /* Missing (lost) #GP error code */
/*
* Adjust our frame so that we return straight to the #GP
* vector with the expected RSP value. This is safe because
* we won't enable interupts or schedule before we invoke
* general_protection, so nothing will clobber the stack
* frame we just set up.
*
* We will enter general_protection with kernel GSBASE,
* which is what the stub expects, given that the faulting
* RIP will be the IRET instruction.
*/
regs->ip = (unsigned long)general_protection;
regs->sp = (unsigned long)&gpregs->orig_ax;
return;
}
#endif
ist_enter(regs);
notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
tsk->thread.error_code = error_code;
tsk->thread.trap_nr = X86_TRAP_DF;
#ifdef CONFIG_VMAP_STACK
/*
* If we overflow the stack into a guard page, the CPU will fail
* to deliver #PF and will send #DF instead. Similarly, if we
* take any non-IST exception while too close to the bottom of
* the stack, the processor will get a page fault while
* delivering the exception and will generate a double fault.
*
* According to the SDM (footnote in 6.15 under "Interrupt 14 -
* Page-Fault Exception (#PF):
*
* Processors update CR2 whenever a page fault is detected. If a
* second page fault occurs while an earlier page fault is being
* delivered, the faulting linear address of the second fault will
* overwrite the contents of CR2 (replacing the previous
* address). These updates to CR2 occur even if the page fault
* results in a double fault or occurs during the delivery of a
* double fault.
*
* The logic below has a small possibility of incorrectly diagnosing
* some errors as stack overflows. For example, if the IDT or GDT
* gets corrupted such that #GP delivery fails due to a bad descriptor
* causing #GP and we hit this condition while CR2 coincidentally
* points to the stack guard page, we'll think we overflowed the
* stack. Given that we're going to panic one way or another
* if this happens, this isn't necessarily worth fixing.
*
* If necessary, we could improve the test by only diagnosing
* a stack overflow if the saved RSP points within 47 bytes of
* the bottom of the stack: if RSP == tsk_stack + 48 and we
* take an exception, the stack is already aligned and there
* will be enough room SS, RSP, RFLAGS, CS, RIP, and a
* possible error code, so a stack overflow would *not* double
* fault. With any less space left, exception delivery could
* fail, and, as a practical matter, we've overflowed the
* stack even if the actual trigger for the double fault was
* something else.
*/
cr2 = read_cr2();
if ((unsigned long)task_stack_page(tsk) - 1 - cr2 < PAGE_SIZE)
handle_stack_overflow("kernel stack overflow (double-fault)", regs, cr2);
#endif
#ifdef CONFIG_DOUBLEFAULT
df_debug(regs, error_code);
#endif
/*
* This is always a kernel trap and never fixable (and thus must
* never return).
*/
for (;;)
die(str, regs, error_code);
}
#endif
dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
{
const struct mpx_bndcsr *bndcsr;
RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
if (notify_die(DIE_TRAP, "bounds", regs, error_code,
X86_TRAP_BR, SIGSEGV) == NOTIFY_STOP)
return;
cond_local_irq_enable(regs);
if (!user_mode(regs))
die("bounds", regs, error_code);
if (!cpu_feature_enabled(X86_FEATURE_MPX)) {
/* The exception is not from Intel MPX */
goto exit_trap;
}
/*
* We need to look at BNDSTATUS to resolve this exception.
* A NULL here might mean that it is in its 'init state',
* which is all zeros which indicates MPX was not
* responsible for the exception.
*/
bndcsr = get_xsave_field_ptr(XFEATURE_MASK_BNDCSR);
if (!bndcsr)
goto exit_trap;
trace_bounds_exception_mpx(bndcsr);
/*
* The error code field of the BNDSTATUS register communicates status
* information of a bound range exception #BR or operation involving
* bound directory.
*/
switch (bndcsr->bndstatus & MPX_BNDSTA_ERROR_CODE) {
case 2: /* Bound directory has invalid entry. */
if (mpx_handle_bd_fault())
goto exit_trap;
break; /* Success, it was handled */
case 1: /* Bound violation. */
{
struct task_struct *tsk = current;
struct mpx_fault_info mpx;
if (mpx_fault_info(&mpx, regs)) {
/*
* We failed to decode the MPX instruction. Act as if
* the exception was not caused by MPX.
*/
goto exit_trap;
}
/*
* Success, we decoded the instruction and retrieved
* an 'mpx' containing the address being accessed
* which caused the exception. This information
* allows and application to possibly handle the
* #BR exception itself.
*/
if (!do_trap_no_signal(tsk, X86_TRAP_BR, "bounds", regs,
error_code))
break;
show_signal(tsk, SIGSEGV, "trap ", "bounds", regs, error_code);
force_sig_bnderr(mpx.addr, mpx.lower, mpx.upper);
break;
}
case 0: /* No exception caused by Intel MPX operations. */
goto exit_trap;
default:
die("bounds", regs, error_code);
}
return;
exit_trap:
/*
* This path out is for all the cases where we could not
* handle the exception in some way (like allocating a
* table or telling userspace about it. We will also end
* up here if the kernel has MPX turned off at compile
* time..
*/
do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, 0, NULL);
}
dotraplinkage void
do_general_protection(struct pt_regs *regs, long error_code)
{
const char *desc = "general protection fault";
struct task_struct *tsk;
RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
cond_local_irq_enable(regs);
if (static_cpu_has(X86_FEATURE_UMIP)) {
if (user_mode(regs) && fixup_umip_exception(regs))
return;
}
if (v8086_mode(regs)) {
local_irq_enable();
handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
return;
}
tsk = current;
if (!user_mode(regs)) {
if (fixup_exception(regs, X86_TRAP_GP, error_code, 0))
return;
tsk->thread.error_code = error_code;
tsk->thread.trap_nr = X86_TRAP_GP;
/*
* To be potentially processing a kprobe fault and to
* trust the result from kprobe_running(), we have to
* be non-preemptible.
*/
if (!preemptible() && kprobe_running() &&
kprobe_fault_handler(regs, X86_TRAP_GP))
return;
if (notify_die(DIE_GPF, desc, regs, error_code,
X86_TRAP_GP, SIGSEGV) != NOTIFY_STOP)
die(desc, regs, error_code);
return;
}
tsk->thread.error_code = error_code;
tsk->thread.trap_nr = X86_TRAP_GP;
show_signal(tsk, SIGSEGV, "", desc, regs, error_code);
force_sig(SIGSEGV, tsk);
}
NOKPROBE_SYMBOL(do_general_protection);
dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
{
#ifdef CONFIG_DYNAMIC_FTRACE
/*
* ftrace must be first, everything else may cause a recursive crash.
* See note by declaration of modifying_ftrace_code in ftrace.c
*/
if (unlikely(atomic_read(&modifying_ftrace_code)) &&
ftrace_int3_handler(regs))
return;
#endif
if (poke_int3_handler(regs))
return;
/*
* Use ist_enter despite the fact that we don't use an IST stack.
* We can be called from a kprobe in non-CONTEXT_KERNEL kernel
* mode or even during context tracking state changes.
*
* This means that we can't schedule. That's okay.
*/
ist_enter(regs);
RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
SIGTRAP) == NOTIFY_STOP)
goto exit;
#endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
#ifdef CONFIG_KPROBES
if (kprobe_int3_handler(regs))
goto exit;
#endif
if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
SIGTRAP) == NOTIFY_STOP)
goto exit;
cond_local_irq_enable(regs);
do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, 0, NULL);
cond_local_irq_disable(regs);
exit:
ist_exit(regs);
}
NOKPROBE_SYMBOL(do_int3);
#ifdef CONFIG_X86_64
/*
* Help handler running on a per-cpu (IST or entry trampoline) stack
* to switch to the normal thread stack if the interrupted code was in
* user mode. The actual stack switch is done in entry_64.S
*/
asmlinkage __visible notrace struct pt_regs *sync_regs(struct pt_regs *eregs)
{
struct pt_regs *regs = (struct pt_regs *)this_cpu_read(cpu_current_top_of_stack) - 1;
if (regs != eregs)
*regs = *eregs;
return regs;
}
NOKPROBE_SYMBOL(sync_regs);
struct bad_iret_stack {
void *error_entry_ret;
struct pt_regs regs;
};
asmlinkage __visible notrace
struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
{
/*
* This is called from entry_64.S early in handling a fault
* caused by a bad iret to user mode. To handle the fault
* correctly, we want to move our stack frame to where it would
* be had we entered directly on the entry stack (rather than
* just below the IRET frame) and we want to pretend that the
* exception came from the IRET target.
*/
struct bad_iret_stack *new_stack =
(struct bad_iret_stack *)this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1;
/* Copy the IRET target to the new stack. */
memmove(&new_stack->regs.ip, (void *)s->regs.sp, 5*8);
/* Copy the remainder of the stack from the current stack. */
memmove(new_stack, s, offsetof(struct bad_iret_stack, regs.ip));
BUG_ON(!user_mode(&new_stack->regs));
return new_stack;
}
NOKPROBE_SYMBOL(fixup_bad_iret);
#endif
static bool is_sysenter_singlestep(struct pt_regs *regs)
{
/*
* We don't try for precision here. If we're anywhere in the region of
* code that can be single-stepped in the SYSENTER entry path, then
* assume that this is a useless single-step trap due to SYSENTER
* being invoked with TF set. (We don't know in advance exactly
* which instructions will be hit because BTF could plausibly
* be set.)
*/
#ifdef CONFIG_X86_32
return (regs->ip - (unsigned long)__begin_SYSENTER_singlestep_region) <
(unsigned long)__end_SYSENTER_singlestep_region -
(unsigned long)__begin_SYSENTER_singlestep_region;
#elif defined(CONFIG_IA32_EMULATION)
return (regs->ip - (unsigned long)entry_SYSENTER_compat) <
(unsigned long)__end_entry_SYSENTER_compat -
(unsigned long)entry_SYSENTER_compat;
#else
return false;
#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)
*
* May run on IST stack.
*/
dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
{
struct task_struct *tsk = current;
int user_icebp = 0;
unsigned long dr6;
int si_code;
ist_enter(regs);
get_debugreg(dr6, 6);
/*
* The Intel SDM says:
*
* Certain debug exceptions may clear bits 0-3. The remaining
* contents of the DR6 register are never cleared by the
* processor. To avoid confusion in identifying debug
* exceptions, debug handlers should clear the register before
* returning to the interrupted task.
*
* Keep it simple: clear DR6 immediately.
*/
set_debugreg(0, 6);
/* Filter out all the reserved bits which are preset to 1 */
dr6 &= ~DR6_RESERVED;
/*
* The SDM says "The processor clears the BTF flag when it
* generates a debug exception." Clear TIF_BLOCKSTEP to keep
* TIF_BLOCKSTEP in sync with the hardware BTF flag.
*/
clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP);
if (unlikely(!user_mode(regs) && (dr6 & DR_STEP) &&
is_sysenter_singlestep(regs))) {
dr6 &= ~DR_STEP;
if (!dr6)
goto exit;
/*
* else we might have gotten a single-step trap and hit a
* watchpoint at the same time, in which case we should fall
* through and handle the watchpoint.
*/
}
/*
* If dr6 has no reason to give us about the origin of this trap,
* then it's very likely the result of an icebp/int01 trap.
* User wants a sigtrap for that.
*/
if (!dr6 && user_mode(regs))
user_icebp = 1;
/* Store the virtualized DR6 value */
tsk->thread.debugreg6 = dr6;
#ifdef CONFIG_KPROBES
if (kprobe_debug_handler(regs))
goto exit;
#endif
if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, error_code,
SIGTRAP) == NOTIFY_STOP)
goto exit;
/*
* Let others (NMI) know that the debug stack is in use
* as we may switch to the interrupt stack.
*/
debug_stack_usage_inc();
/* It's safe to allow irq's after DR6 has been saved */
cond_local_irq_enable(regs);
if (v8086_mode(regs)) {
handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code,
X86_TRAP_DB);
cond_local_irq_disable(regs);
debug_stack_usage_dec();
goto exit;
}
if (WARN_ON_ONCE((dr6 & DR_STEP) && !user_mode(regs))) {
/*
* Historical junk that used to handle SYSENTER single-stepping.
* This should be unreachable now. If we survive for a while
* without anyone hitting this warning, we'll turn this into
* an oops.
*/
tsk->thread.debugreg6 &= ~DR_STEP;
set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
regs->flags &= ~X86_EFLAGS_TF;
}
si_code = get_si_code(tsk->thread.debugreg6);
if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)
send_sigtrap(tsk, regs, error_code, si_code);
cond_local_irq_disable(regs);
debug_stack_usage_dec();
exit:
ist_exit(regs);
}
NOKPROBE_SYMBOL(do_debug);
/*
* 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
*/
static void math_error(struct pt_regs *regs, int error_code, int trapnr)
{
struct task_struct *task = current;
struct fpu *fpu = &task->thread.fpu;
int si_code;
char *str = (trapnr == X86_TRAP_MF) ? "fpu exception" :
"simd exception";
cond_local_irq_enable(regs);
if (!user_mode(regs)) {
if (fixup_exception(regs, trapnr, error_code, 0))
return;
task->thread.error_code = error_code;
task->thread.trap_nr = trapnr;
if (notify_die(DIE_TRAP, str, regs, error_code,
trapnr, SIGFPE) != NOTIFY_STOP)
die(str, regs, error_code);
return;
}
/*
* Save the info for the exception handler and clear the error.
*/
fpu__save(fpu);
task->thread.trap_nr = trapnr;
task->thread.error_code = error_code;
si_code = fpu__exception_code(fpu, trapnr);
/* Retry when we get spurious exceptions: */
if (!si_code)
return;
force_sig_fault(SIGFPE, si_code,
(void __user *)uprobe_get_trap_addr(regs), task);
}
dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
{
RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
math_error(regs, error_code, X86_TRAP_MF);
}
dotraplinkage void
do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
{
RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
math_error(regs, error_code, X86_TRAP_XF);
}
dotraplinkage void
do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
{
cond_local_irq_enable(regs);
}
dotraplinkage void
do_device_not_available(struct pt_regs *regs, long error_code)
{
unsigned long cr0;
RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
#ifdef CONFIG_MATH_EMULATION
if (!boot_cpu_has(X86_FEATURE_FPU) && (read_cr0() & X86_CR0_EM)) {
struct math_emu_info info = { };
cond_local_irq_enable(regs);
info.regs = regs;
math_emulate(&info);
return;
}
#endif
/* This should not happen. */
cr0 = read_cr0();
if (WARN(cr0 & X86_CR0_TS, "CR0.TS was set")) {
/* Try to fix it up and carry on. */
write_cr0(cr0 & ~X86_CR0_TS);
} else {
/*
* Something terrible happened, and we're better off trying
* to kill the task than getting stuck in a never-ending
* loop of #NM faults.
*/
die("unexpected #NM exception", regs, error_code);
}
}
NOKPROBE_SYMBOL(do_device_not_available);
#ifdef CONFIG_X86_32
dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
{
RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
local_irq_enable();
if (notify_die(DIE_TRAP, "iret exception", regs, error_code,
X86_TRAP_IRET, SIGILL) != NOTIFY_STOP) {
do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code,
ILL_BADSTK, (void __user *)NULL);
}
}
#endif
void __init trap_init(void)
{
/* Init cpu_entry_area before IST entries are set up */
setup_cpu_entry_areas();
idt_setup_traps();
/*
* Set the IDT descriptor to a fixed read-only location, so that the
* "sidt" instruction will not leak the location of the kernel, and
* to defend the IDT against arbitrary memory write vulnerabilities.
* It will be reloaded in cpu_init() */
cea_set_pte(CPU_ENTRY_AREA_RO_IDT_VADDR, __pa_symbol(idt_table),
PAGE_KERNEL_RO);
idt_descr.address = CPU_ENTRY_AREA_RO_IDT;
/*
* Should be a barrier for any external CPU state:
*/
cpu_init();
idt_setup_ist_traps();
x86_init.irqs.trap_init();
idt_setup_debugidt_traps();
}