diff options
| author | Andy Lutomirski <luto@kernel.org> | 2020-02-25 22:36:46 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2020-02-27 15:28:39 +0100 |
| commit | 65c668f5faebf549db086b7a6841b6f4187b4e4f (patch) | |
| tree | 1533c79fdb1436275891ada9289f5a7ec5ee3cc9 /arch | |
| parent | ac3607f92f70c762e24d0ae731168f7584de51ec (diff) | |
x86/traps: Stop using ist_enter/exit() in do_int3()
#BP is not longer using IST and using ist_enter() and ist_exit() makes it
harder to change ist_enter() and ist_exit()'s behavior. Instead open-code
the very small amount of required logic.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200225220217.150607679@linutronix.de
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/traps.c | 21 |
1 files changed, 15 insertions, 6 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 7ffb6f4dea1c..c0bc9df8634d 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -572,14 +572,20 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code) return; /* - * Use ist_enter despite the fact that we don't use an IST stack. - * We can be called from a kprobe in non-CONTEXT_KERNEL kernel - * mode or even during context tracking state changes. + * Unlike any other non-IST entry, we can be called from a kprobe in + * non-CONTEXT_KERNEL kernel mode or even during context tracking + * state changes. Make sure that we wake up RCU even if we're coming + * from kernel code. * - * This means that we can't schedule. That's okay. + * This means that we can't schedule even if we came from a + * preemptible kernel context. That's okay. */ - ist_enter(regs); + if (!user_mode(regs)) { + rcu_nmi_enter(); + preempt_disable(); + } RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); + #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP, SIGTRAP) == NOTIFY_STOP) @@ -600,7 +606,10 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code) cond_local_irq_disable(regs); exit: - ist_exit(regs); + if (!user_mode(regs)) { + preempt_enable_no_resched(); + rcu_nmi_exit(); + } } NOKPROBE_SYMBOL(do_int3); |