From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Steven Rostedt <rostedt@goodmis.org>,
Brian Gerst <brgerst@gmail.com>, Juergen Gross <jgross@suse.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Arnd Bergmann <arnd@arndb.de>, Andy Lutomirski <luto@kernel.org>
Subject: [patch 10/10] x86/traps: Stop using ist_enter/exit() in do_int3()
Date: Tue, 25 Feb 2020 22:36:46 +0100 [thread overview]
Message-ID: <20200225220217.150607679@linutronix.de> (raw)
In-Reply-To: 20200225213636.689276920@linutronix.de
#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>
---
arch/x86/kernel/traps.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -572,14 +572,20 @@ dotraplinkage void notrace do_int3(struc
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(struc
cond_local_irq_disable(regs);
exit:
- ist_exit(regs);
+ if (!user_mode(regs)) {
+ preempt_enable_no_resched();
+ rcu_nmi_exit();
+ }
}
NOKPROBE_SYMBOL(do_int3);
next prev parent reply other threads:[~2020-02-25 23:30 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-25 21:36 [patch 00/10] x86/entry: Consolidation - Part I Thomas Gleixner
2020-02-25 21:36 ` [patch 01/10] x86/entry/32: Add missing ASM_CLAC to general_protection entry Thomas Gleixner
2020-02-26 1:00 ` Frederic Weisbecker
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 02/10] x86/mce: Disable tracing and kprobes on do_machine_check() Thomas Gleixner
2020-02-26 1:13 ` Frederic Weisbecker
2020-02-26 5:29 ` Andy Lutomirski
2020-02-26 13:28 ` Peter Zijlstra
2020-02-26 15:10 ` Andy Lutomirski
2020-02-26 16:08 ` Peter Zijlstra
2020-02-26 17:28 ` Andy Lutomirski
2020-02-26 18:42 ` Borislav Petkov
2020-02-26 18:59 ` Peter Zijlstra
2020-02-26 19:09 ` Andy Lutomirski
2020-02-26 20:59 ` Steven Rostedt
2020-02-26 11:18 ` Borislav Petkov
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Andy Lutomirski
2020-02-25 21:36 ` [patch 03/10] x86/entry/32: Force MCE through do_mce() Thomas Gleixner
2020-02-26 1:11 ` Frederic Weisbecker
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 04/10] x86/traps: Remove pointless irq enable from do_spurious_interrupt_bug() Thomas Gleixner
2020-02-26 1:19 ` Frederic Weisbecker
2020-02-25 21:36 ` [patch 05/10] x86/traps: Document do_spurious_interrupt_bug() Thomas Gleixner
2020-02-26 17:08 ` Frederic Weisbecker
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 06/10] x86/traps: Remove redundant declaration of do_double_fault() Thomas Gleixner
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 07/10] x86/irq: Remove useless return value from do_IRQ() Thomas Gleixner
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 08/10] x86/entry/32: Remove the 0/-1 distinction from exception entries Thomas Gleixner
2020-02-26 5:34 ` Andy Lutomirski
2020-02-26 18:42 ` Thomas Gleixner
2020-02-26 18:57 ` Andy Lutomirski
2020-02-26 19:15 ` Thomas Gleixner
2020-02-27 14:24 ` [patch V2 " Thomas Gleixner
2020-02-29 11:49 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 09/10] x86/entry/entry_32: Route int3 through common_exception Thomas Gleixner
2020-02-26 17:35 ` Frederic Weisbecker
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` Thomas Gleixner [this message]
2020-02-27 14:15 ` [tip: x86/entry] x86/traps: Stop using ist_enter/exit() in do_int3() tip-bot2 for Thomas Gleixner
2020-02-27 14:33 ` tip-bot2 for Andy Lutomirski
2020-02-26 5:26 ` [patch 00/10] x86/entry: Consolidation - Part I Andy Lutomirski
2020-02-26 5:35 ` Andy Lutomirski
2020-02-27 11:01 ` Alexandre Chartre
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200225220217.150607679@linutronix.de \
--to=tglx@linutronix.de \
--cc=arnd@arndb.de \
--cc=brgerst@gmail.com \
--cc=jgross@suse.com \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=pbonzini@redhat.com \
--cc=rostedt@goodmis.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).