linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Alexey Dobriyan <adobriyan@gmail.com>
To: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com
Cc: x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] x86_64: fixup TASK_SIZE_MAX comment
Date: Thu, 5 Mar 2020 21:17:19 +0300	[thread overview]
Message-ID: <20200305181719.GA5490@avx2> (raw)

Comment says "by preventing anything executable" which is not true.
Even PROT_NONE mapping can't be installed at (1<<47 - 4096).

	mmap(0x7ffffffff000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = -1 ENOMEM

I wonder if CPUs with wider address space carried the bugs...

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---

 arch/x86/include/asm/processor.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -887,7 +887,7 @@ static inline void spin_lock_prefetch(const void *x)
  * On Intel CPUs, if a SYSCALL instruction is at the highest canonical
  * address, then that syscall will enter the kernel with a
  * non-canonical return address, and SYSRET will explode dangerously.
- * We avoid this particular problem by preventing anything executable
+ * We avoid this particular problem by preventing anything
  * from being mapped at the maximum canonical address.
  *
  * On AMD CPUs in the Ryzen family, there's a nasty bug in which the

             reply	other threads:[~2020-03-05 18:17 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-05 18:17 Alexey Dobriyan [this message]
2020-03-06 18:09 ` Andy Lutomirski
2021-02-05  9:43 ` [tip: x86/cleanups] x86/asm: Fixup " tip-bot2 for Alexey Dobriyan

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=20200305181719.GA5490@avx2 \
    --to=adobriyan@gmail.com \
    --cc=bp@alien8.de \
    --cc=hpa@zytor.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=tglx@linutronix.de \
    --cc=x86@kernel.org \
    --subject='Re: [PATCH] x86_64: fixup TASK_SIZE_MAX comment' \
    /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

This is a public inbox, see mirroring instructions
on how to clone and mirror all data and code used for this inbox