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x86/entry: Get rid of ist_begin/end_non_atomic()

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This is completely overengineered and definitely not an interface which
should be made available to anything else than this particular MCE case.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200505134059.462640294@linutronix.de
This commit is contained in:
Thomas Gleixner 2020-03-05 00:52:41 +01:00
parent f93524eb9c
commit b052df3da8
3 changed files with 4 additions and 41 deletions
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2
arch/x86/include/asm/traps.h
View File

@ -120,8 +120,6 @@ asmlinkage void smp_irq_move_cleanup_interrupt(void);
extern void ist_enter(struct pt_regs *regs); extern void ist_enter(struct pt_regs *regs);
extern void ist_exit(struct pt_regs *regs); extern void ist_exit(struct pt_regs *regs);
extern void ist_begin_non_atomic(struct pt_regs *regs);
extern void ist_end_non_atomic(void);
#ifdef CONFIG_VMAP_STACK #ifdef CONFIG_VMAP_STACK
void __noreturn handle_stack_overflow(const char *message, void __noreturn handle_stack_overflow(const char *message,

6
arch/x86/kernel/cpu/mce/core.c
View File

@ -1352,13 +1352,15 @@ void notrace do_machine_check(struct pt_regs *regs, long error_code)
/* Fault was in user mode and we need to take some action */ /* Fault was in user mode and we need to take some action */
if ((m.cs & 3) == 3) { if ((m.cs & 3) == 3) {
ist_begin_non_atomic(regs); /* If this triggers there is no way to recover. Die hard. */
BUG_ON(!on_thread_stack() || !user_mode(regs));
local_irq_enable(); local_irq_enable();
preempt_enable();
if (kill_it || do_memory_failure(&m)) if (kill_it || do_memory_failure(&m))
force_sig(SIGBUS); force_sig(SIGBUS);
preempt_disable();
local_irq_disable(); local_irq_disable();
ist_end_non_atomic();
} else { } else {
if (!fixup_exception(regs, X86_TRAP_MC, error_code, 0)) if (!fixup_exception(regs, X86_TRAP_MC, error_code, 0))
mce_panic("Failed kernel mode recovery", &m, msg); mce_panic("Failed kernel mode recovery", &m, msg);

37
arch/x86/kernel/traps.c
View File

@ -117,43 +117,6 @@ void ist_exit(struct pt_regs *regs)
rcu_nmi_exit(); 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) int is_valid_bugaddr(unsigned long addr)
{ {
unsigned short ud; unsigned short ud;