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Message-Id: <1453036184-15077-1-git-send-email-kuleshovmail@gmail.com>
Date: Sun, 17 Jan 2016 19:09:44 +0600
From: Alexander Kuleshov <kuleshovmail@...il.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>, "H . Peter Anvin" <hpa@...or.com>,
x86@...nel.org, Andy Lutomirski <luto@...nel.org>,
Denys Vlasenko <dvlasenk@...hat.com>,
Borislav Petkov <bp@...e.de>, linux-kernel@...r.kernel.org,
Alexander Kuleshov <kuleshovmail@...il.com>
Subject: [PATCH v2] x86/traps.c: refactor preemption and interrupt flag handling
The arch/x86/kernel/traps.c contains definition of two pair of helpers
conditional_{sti,cli} to enable/disable interrupts depends on state of
the interrupt flag and *preempt* versions of these helpers.
This patch tries to make the preemption and interrupt flag handling more
readable by removing preempt_conditional_sti() and
preempt_conditional_cli() helpers and usage preempt_disable() and
preempt_enable_no_resched() for preemption in place, instead of these helpers.
The contitional_sti() and conditional_cli() are renamed to more understandable
names: cond_local_irq_enable() and cond_local_irq_disable() respectively. So
so that one doesn't have to go and lookup the function definition when
looking at the code flow.
Signed-off-by: Alexander Kuleshov <kuleshovmail@...il.com>
Suggested-by: Borislav Petkov <bp@...e.de>
---
Changelog v2:
1. Use preempt_enable_no_resched() instead of sched_preempt_enable_no_resched()
arch/x86/kernel/traps.c | 47 +++++++++++++++++++----------------------------
1 file changed, 19 insertions(+), 28 deletions(-)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index ade185a..410e8e2 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -83,30 +83,16 @@ gate_desc idt_table[NR_VECTORS] __page_aligned_bss;
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)
@@ -286,7 +272,7 @@ static void do_error_trap(struct pt_regs *regs, long error_code, char *str,
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));
}
@@ -368,7 +354,7 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
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);
@@ -443,7 +429,7 @@ do_general_protection(struct pt_regs *regs, long 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();
@@ -517,9 +503,11 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long 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);
@@ -648,12 +636,14 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
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;
}
@@ -673,7 +663,8 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
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:
@@ -696,7 +687,7 @@ static void math_error(struct pt_regs *regs, int error_code, int trapnr)
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)) {
@@ -743,7 +734,7 @@ do_simd_coprocessor_error(struct pt_regs *regs, long 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
@@ -756,7 +747,7 @@ do_device_not_available(struct pt_regs *regs, long error_code)
if (read_cr0() & X86_CR0_EM) {
struct math_emu_info info = { };
- conditional_sti(regs);
+ cond_local_irq_enable(regs);
info.regs = regs;
math_emulate(&info);
@@ -765,7 +756,7 @@ do_device_not_available(struct pt_regs *regs, long error_code)
#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);
--
2.7.0.25.gfc10eb5
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