| Subject | Re: [patch V4 part 1 14/36] x86/entry: Get rid of ist_begin/end_non_atomic() | From | Alexandre Chartre <> | Date | Wed, 6 May 2020 17:34:31 +0200 |
| |
On 5/5/20 3:16 PM, Thomas Gleixner wrote: > 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> > --- > arch/x86/include/asm/traps.h | 2 -- > arch/x86/kernel/cpu/mce/core.c | 6 ++++-- > arch/x86/kernel/traps.c | 37 ------------------------------------- > 3 files changed, 4 insertions(+), 41 deletions(-)
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
alex.
> --- a/arch/x86/include/asm/traps.h > +++ b/arch/x86/include/asm/traps.h > @@ -120,8 +120,6 @@ asmlinkage void smp_irq_move_cleanup_int > > 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, > --- a/arch/x86/kernel/cpu/mce/core.c > +++ b/arch/x86/kernel/cpu/mce/core.c > @@ -1352,13 +1352,15 @@ void notrace do_machine_check(struct pt_ > > /* 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); > + preempt_disable(); > local_irq_disable(); > - ist_end_non_atomic(); > } else { > if (!fixup_exception(regs, X86_TRAP_MC, error_code, 0)) > mce_panic("Failed kernel mode recovery", &m, msg); > --- a/arch/x86/kernel/traps.c > +++ b/arch/x86/kernel/traps.c > @@ -117,43 +117,6 @@ 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; >
|