From 432c4786b9dd6104c994961c7cac3ff356f44416 Mon Sep 17 00:00:00 2001 From: Youquan Song Date: Mon, 6 Jul 2020 22:13:25 +0800 Subject: [PATCH] x86/entry: Get rid of ist_begin/end_non_atomic() fix #29415191 commit b052df3da821adfd6be26a6eb16624fb50e90e56 upstream 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 Reviewed-by: Alexandre Chartre Acked-by: Peter Zijlstra Link: https://lkml.kernel.org/r/20200505134059.462640294@linutronix.de Signed-off-by: Youquan Song Signed-off-by: Wetp Zhang Reviewed-by: Artie Ding --- arch/x86/include/asm/traps.h | 2 -- arch/x86/kernel/cpu/mcheck/mce.c | 6 ++++-- arch/x86/kernel/traps.c | 37 -------------------------------- 3 files changed, 4 insertions(+), 41 deletions(-) diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h index b771bb3d159b..b44d74009ec3 100644 --- a/arch/x86/include/asm/traps.h +++ b/arch/x86/include/asm/traps.h @@ -111,8 +111,6 @@ asmlinkage void smp_deferred_error_interrupt(struct pt_regs *regs); extern void ist_enter(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 void __noreturn handle_stack_overflow(const char *message, diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index a8eb20a0f8eb..5cd04a315964 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -1350,13 +1350,15 @@ void do_machine_check(struct pt_regs *regs, long error_code) /* Fault was in user mode and we need to take some action */ 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(); + preempt_enable(); if (kill_it || do_memory_failure(&m)) force_sig(SIGBUS, current); + preempt_disable(); local_irq_disable(); - ist_end_non_atomic(); } else { if (!fixup_exception(regs, X86_TRAP_MC)) mce_panic("Failed kernel mode recovery", &m, NULL); diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index e6db475164ed..b757098e4585 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -120,43 +120,6 @@ void ist_exit(struct pt_regs *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; -- GitLab