DECLARE_BITMAP(used_vectors, NR_VECTORS);
EXPORT_SYMBOL_GPL(used_vectors);
-static inline void conditional_sti(struct pt_regs *regs)
+static inline void cond_local_irq_enable(struct pt_regs *regs)
{
if (regs->flags & X86_EFLAGS_IF)
local_irq_enable();
}
-static inline void preempt_conditional_sti(struct pt_regs *regs)
-{
- preempt_count_inc();
- if (regs->flags & X86_EFLAGS_IF)
- local_irq_enable();
-}
-
-static inline void conditional_cli(struct pt_regs *regs)
-{
- if (regs->flags & X86_EFLAGS_IF)
- local_irq_disable();
-}
-
-static inline void preempt_conditional_cli(struct pt_regs *regs)
+static inline void cond_local_irq_disable(struct pt_regs *regs)
{
if (regs->flags & X86_EFLAGS_IF)
local_irq_disable();
- preempt_count_dec();
}
void ist_enter(struct pt_regs *regs)
}
if (!user_mode(regs)) {
- if (!fixup_exception(regs)) {
+ if (!fixup_exception(regs, trapnr)) {
tsk->thread.error_code = error_code;
tsk->thread.trap_nr = trapnr;
die(str, regs, error_code);
tsk->thread.error_code = error_code;
tsk->thread.trap_nr = trapnr;
-#ifdef CONFIG_X86_64
if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
printk_ratelimit()) {
pr_info("%s[%d] trap %s ip:%lx sp:%lx error:%lx",
print_vma_addr(" in ", regs->ip);
pr_cont("\n");
}
-#endif
force_sig_info(signr, info ?: SEND_SIG_PRIV, tsk);
}
if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) !=
NOTIFY_STOP) {
- conditional_sti(regs);
+ cond_local_irq_enable(regs);
do_trap(trapnr, signr, str, regs, error_code,
fill_trap_info(regs, signr, trapnr, &info));
}
if (notify_die(DIE_TRAP, "bounds", regs, error_code,
X86_TRAP_BR, SIGSEGV) == NOTIFY_STOP)
return;
- conditional_sti(regs);
+ cond_local_irq_enable(regs);
if (!user_mode(regs))
die("bounds", regs, error_code);
struct task_struct *tsk;
RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
- conditional_sti(regs);
+ cond_local_irq_enable(regs);
if (v8086_mode(regs)) {
local_irq_enable();
tsk = current;
if (!user_mode(regs)) {
- if (fixup_exception(regs))
+ if (fixup_exception(regs, X86_TRAP_GP))
return;
tsk->thread.error_code = error_code;
* as we may switch to the interrupt stack.
*/
debug_stack_usage_inc();
- preempt_conditional_sti(regs);
+ preempt_disable();
+ cond_local_irq_enable(regs);
do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL);
- preempt_conditional_cli(regs);
+ cond_local_irq_disable(regs);
+ preempt_enable_no_resched();
debug_stack_usage_dec();
exit:
ist_exit(regs);
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
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.
if (!dr6 && user_mode(regs))
user_icebp = 1;
- /* Catch kmemcheck conditions first of all! */
+ /* Catch kmemcheck conditions! */
if ((dr6 & DR_STEP) && kmemcheck_trap(regs))
goto exit;
- /* DR6 may or may not be cleared by the CPU */
- set_debugreg(0, 6);
-
- /*
- * The processor cleared BTF, so don't mark that we need it set.
- */
- clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP);
-
/* Store the virtualized DR6 value */
tsk->thread.debugreg6 = dr6;
debug_stack_usage_inc();
/* It's safe to allow irq's after DR6 has been saved */
- preempt_conditional_sti(regs);
+ preempt_disable();
+ cond_local_irq_enable(regs);
if (v8086_mode(regs)) {
handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code,
X86_TRAP_DB);
- preempt_conditional_cli(regs);
+ cond_local_irq_disable(regs);
+ preempt_enable_no_resched();
debug_stack_usage_dec();
goto exit;
}
- /*
- * Single-stepping through system calls: ignore any exceptions in
- * kernel space, but re-enable TF when returning to user mode.
- *
- * We already checked v86 mode above, so we can check for kernel mode
- * by just checking the CPL of CS.
- */
- if ((dr6 & DR_STEP) && !user_mode(regs)) {
+ 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);
- preempt_conditional_cli(regs);
+ cond_local_irq_disable(regs);
+ preempt_enable_no_resched();
debug_stack_usage_dec();
exit:
+#if defined(CONFIG_X86_32)
+ /*
+ * This is the most likely code path that involves non-trivial use
+ * of the SYSENTER stack. Check that we haven't overrun it.
+ */
+ WARN(this_cpu_read(cpu_tss.SYSENTER_stack_canary) != STACK_END_MAGIC,
+ "Overran or corrupted SYSENTER stack\n");
+#endif
ist_exit(regs);
}
NOKPROBE_SYMBOL(do_debug);
if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, SIGFPE) == NOTIFY_STOP)
return;
- conditional_sti(regs);
+ cond_local_irq_enable(regs);
if (!user_mode(regs)) {
- if (!fixup_exception(regs)) {
+ if (!fixup_exception(regs, trapnr)) {
task->thread.error_code = error_code;
task->thread.trap_nr = trapnr;
die(str, regs, error_code);
dotraplinkage void
do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
{
- conditional_sti(regs);
+ cond_local_irq_enable(regs);
}
dotraplinkage void
if (!boot_cpu_has(X86_FEATURE_FPU) && (read_cr0() & X86_CR0_EM)) {
struct math_emu_info info = { };
- conditional_sti(regs);
+ cond_local_irq_enable(regs);
info.regs = regs;
math_emulate(&info);
#endif
fpu__restore(¤t->thread.fpu); /* interrupts still off */
#ifdef CONFIG_X86_32
- conditional_sti(regs);
+ cond_local_irq_enable(regs);
#endif
}
NOKPROBE_SYMBOL(do_device_not_available);
#endif
#ifdef CONFIG_X86_32
- set_system_trap_gate(IA32_SYSCALL_VECTOR, entry_INT80_32);
+ set_system_intr_gate(IA32_SYSCALL_VECTOR, entry_INT80_32);
set_bit(IA32_SYSCALL_VECTOR, used_vectors);
#endif
projects / linux-2.6-block.git / blobdiff