From: Borislav Petkov <bp@alien8.de>
To: X86 ML <x86@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Andy Lutomirski <luto@amacapital.net>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: [PATCH] x86/traps: Have read_cr0() only once in the #NM handler
Date: Thu, 17 Jan 2019 13:07:28 +0100 [thread overview]
Message-ID: <20190117120728.3811-1-bp@alien8.de> (raw)
From: Borislav Petkov <bp@suse.de>
... instead of twice in the code. In any case, CR0 ends up being read
once anyway:
1. The CONFIG_MATH_EMULATION case does so and exits.
2. The normal case does it once too.
However, read it on function entry instead to make the code even simpler
to follow.
No functional changes.
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
arch/x86/kernel/traps.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 9b7c4ca8f0a7..2684a9d11e66 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -880,12 +880,12 @@ do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
dotraplinkage void
do_device_not_available(struct pt_regs *regs, long error_code)
{
- unsigned long cr0;
+ unsigned long cr0 = read_cr0();
RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
#ifdef CONFIG_MATH_EMULATION
- if (!boot_cpu_has(X86_FEATURE_FPU) && (read_cr0() & X86_CR0_EM)) {
+ if (!boot_cpu_has(X86_FEATURE_FPU) && (cr0 & X86_CR0_EM)) {
struct math_emu_info info = { };
cond_local_irq_enable(regs);
@@ -897,7 +897,6 @@ do_device_not_available(struct pt_regs *regs, long error_code)
#endif
/* This should not happen. */
- cr0 = read_cr0();
if (WARN(cr0 & X86_CR0_TS, "CR0.TS was set")) {
/* Try to fix it up and carry on. */
write_cr0(cr0 & ~X86_CR0_TS);
--
2.19.1
next reply other threads:[~2019-01-17 12:07 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-17 12:07 Borislav Petkov [this message]
2019-01-17 12:14 ` [PATCH] x86/traps: Have read_cr0() only once in the #NM handler Sebastian Andrzej Siewior
2019-01-17 19:24 ` Andy Lutomirski
2019-01-22 13:30 ` [tip:x86/fpu] " tip-bot for Borislav Petkov
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=20190117120728.3811-1-bp@alien8.de \
--to=bp@alien8.de \
--cc=bigeasy@linutronix.de \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@amacapital.net \
--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).