From: "tip-bot2 for Peter Zijlstra" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>, Kyle Huey <me@kylehuey.com>,
x86 <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: [tip: x86/urgent] x86/debug: Only clear/set ->virtual_dr6 for userspace #DB
Date: Tue, 27 Oct 2020 22:19:10 -0000 [thread overview]
Message-ID: <160383715005.397.4679134647227236896.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20201027093608.028952500@infradead.org>
The following commit has been merged into the x86/urgent branch of tip:
Commit-ID: a195f3d4528a2f88d6f986f6b1101775ad4891cf
Gitweb: https://git.kernel.org/tip/a195f3d4528a2f88d6f986f6b1101775ad4891cf
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Tue, 27 Oct 2020 10:15:06 +01:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Tue, 27 Oct 2020 23:15:23 +01:00
x86/debug: Only clear/set ->virtual_dr6 for userspace #DB
The ->virtual_dr6 is the value used by ptrace_{get,set}_debugreg(6). A
kernel #DB clearing it could mean spurious malfunction of ptrace()
expectations.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Kyle Huey <me@kylehuey.com>
Link: https://lore.kernel.org/r/20201027093608.028952500@infradead.org
---
arch/x86/kernel/traps.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index b5208aa..32b2d39 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -793,12 +793,6 @@ static __always_inline unsigned long debug_read_clear_dr6(void)
set_debugreg(DR6_RESERVED, 6);
dr6 ^= DR6_RESERVED; /* Flip to positive polarity */
- /*
- * Clear the virtual DR6 value, ptrace routines will set bits here for
- * things we want signals for.
- */
- current->thread.virtual_dr6 = 0;
-
return dr6;
}
@@ -943,6 +937,12 @@ static __always_inline void exc_debug_user(struct pt_regs *regs,
instrumentation_begin();
/*
+ * Clear the virtual DR6 value, ptrace() routines will set bits here
+ * for things it wants signals for.
+ */
+ current->thread.virtual_dr6 = 0;
+
+ /*
* The SDM says "The processor clears the BTF flag when it
* generates a debug exception." Clear TIF_BLOCKSTEP to keep
* TIF_BLOCKSTEP in sync with the hardware BTF flag.
next prev parent reply other threads:[~2020-10-27 22:19 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-27 9:15 [PATCH 0/3] x86/debug: Fixes Peter Zijlstra
2020-10-27 9:15 ` [PATCH 1/3] x86/debug: Fix BTF handling Peter Zijlstra
2020-10-27 19:41 ` Peter Zijlstra
2020-10-28 9:20 ` Masami Hiramatsu
2020-10-28 9:59 ` Peter Zijlstra
2020-10-28 12:11 ` Masami Hiramatsu
2020-10-28 14:31 ` [PATCH] x86/kprobes: Restore BTF if the single-stepping is cancelled Masami Hiramatsu
2020-12-07 23:22 ` Steven Rostedt
2020-12-09 18:44 ` [tip: perf/core] " tip-bot2 for Masami Hiramatsu
2020-10-27 22:19 ` [tip: x86/urgent] x86/debug: Fix BTF handling tip-bot2 for Peter Zijlstra
2020-10-27 9:15 ` [PATCH 2/3] x86/debug: Only clear/set ->virtual_dr6 for userspace #DB Peter Zijlstra
2020-10-27 22:19 ` tip-bot2 for Peter Zijlstra [this message]
2020-10-27 9:15 ` [PATCH 3/3] x86/debug: Fix PTRACE_{BLOCK,SINGLE}STEP vs ptrace_get_debugreg(6) Peter Zijlstra
2020-10-27 17:22 ` Kyle Huey
2020-10-27 18:33 ` [PATCH v2 3/3] Fix DR_STEP " Peter Zijlstra
2020-10-27 22:19 ` [tip: x86/urgent] x86/debug: " tip-bot2 for Peter Zijlstra
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=160383715005.397.4679134647227236896.tip-bot2@tip-bot2 \
--to=tip-bot2@linutronix.de \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-tip-commits@vger.kernel.org \
--cc=me@kylehuey.com \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--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).