From: tip-bot for Joerg Roedel <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: brgerst@gmail.com, torvalds@linux-foundation.org,
jroedel@suse.de, hpa@zytor.com, jkosina@suse.cz, acme@kernel.org,
tglx@linutronix.de, eduval@amazon.com, jpoimboe@redhat.com,
dhgutteridge@sympatico.ca, namhyung@kernel.org, llong@redhat.com,
boris.ostrovsky@oracle.com, jolsa@redhat.com,
dave.hansen@intel.com, mingo@kernel.org, bp@alien8.de,
jgross@suse.com, luto@kernel.org, aarcange@redhat.com,
dvlasenk@redhat.com, linux-kernel@vger.kernel.org,
gregkh@linuxfoundation.org, pavel@ucw.cz, will.deacon@arm.com,
David.Laight@aculab.com, peterz@infradead.org,
alexander.shishkin@linux.intel.com
Subject: [tip:x86/pti] perf/core: Make sure the ring-buffer is mapped in all page-tables
Date: Fri, 20 Jul 2018 13:36:52 -0700 [thread overview]
Message-ID: <tip-77754cfa09a6c528c38cbca9ee4cc4f7cf6ad6f2@git.kernel.org> (raw)
In-Reply-To: <1532103744-31902-2-git-send-email-joro@8bytes.org>
Commit-ID: 77754cfa09a6c528c38cbca9ee4cc4f7cf6ad6f2
Gitweb: https://git.kernel.org/tip/77754cfa09a6c528c38cbca9ee4cc4f7cf6ad6f2
Author: Joerg Roedel <jroedel@suse.de>
AuthorDate: Fri, 20 Jul 2018 18:22:22 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 20 Jul 2018 22:33:41 +0200
perf/core: Make sure the ring-buffer is mapped in all page-tables
The ring-buffer is accessed in the NMI handler, so it's better to avoid
faulting on it. Sync the vmalloc range with all page-tables in system to
make sure everyone has it mapped.
This fixes a WARN_ON_ONCE() that can be triggered with PTI enabled on
x86-32:
WARNING: CPU: 4 PID: 0 at arch/x86/mm/fault.c:320 vmalloc_fault+0x220/0x230
This triggers because with PTI enabled on an PAE kernel the PMDs are no
longer shared between the page-tables, so the vmalloc changes do not
propagate automatically.
Note: Andy said rightfully that we should try to fix the vmalloc code for
that case, but that's not a hot fix for the issue at hand.
Fixes: 7757d607c6b3 ("x86/pti: Allow CONFIG_PAGE_TABLE_ISOLATION for x86_32")
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: linux-mm@kvack.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Waiman Long <llong@redhat.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: joro@8bytes.org
Link: https://lkml.kernel.org/r/1532103744-31902-2-git-send-email-joro@8bytes.org
---
kernel/events/ring_buffer.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index 5d3cf407e374..df2d8cf0072c 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -814,6 +814,13 @@ static void rb_free_work(struct work_struct *work)
vfree(base);
kfree(rb);
+
+ /*
+ * FIXME: PAE workaround for vmalloc_fault(): Make sure buffer is
+ * unmapped in all page-tables.
+ */
+ if (IS_ENABLED(CONFIG_X86_PAE))
+ vmalloc_sync_all();
}
void rb_free(struct ring_buffer *rb)
@@ -840,6 +847,15 @@ struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
if (!all_buf)
goto fail_all_buf;
+ /*
+ * FIXME: PAE workaround for vmalloc_fault(): The buffer is
+ * accessed in NMI handlers, make sure it is mapped in all
+ * page-tables in the system so that we don't fault on the range in
+ * an NMI handler.
+ */
+ if (IS_ENABLED(CONFIG_X86_PAE))
+ vmalloc_sync_all();
+
rb->user_page = all_buf;
rb->data_pages[0] = all_buf + PAGE_SIZE;
if (nr_pages) {
next prev parent reply other threads:[~2018-07-20 20:38 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-20 16:22 [PATCH 0/3] PTI for x86-32 Fixes and Updates Joerg Roedel
2018-07-20 16:22 ` [PATCH 1/3] perf/core: Make sure the ring-buffer is mapped in all page-tables Joerg Roedel
2018-07-20 17:06 ` Andy Lutomirski
2018-07-20 17:48 ` Joerg Roedel
2018-07-20 19:32 ` Andy Lutomirski
2018-07-20 21:37 ` Joerg Roedel
2018-07-20 22:20 ` Andy Lutomirski
2018-07-21 21:06 ` Linus Torvalds
2018-07-20 19:27 ` Thomas Gleixner
2018-07-20 19:33 ` Andy Lutomirski
2018-07-20 19:43 ` Thomas Gleixner
2018-07-20 19:53 ` Thomas Gleixner
2018-07-20 19:37 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-20 20:36 ` tip-bot for Joerg Roedel [this message]
2018-07-20 16:22 ` [PATCH 2/3] x86/entry/32: Check for VM86 mode in slow-path check Joerg Roedel
2018-07-20 19:37 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-20 20:37 ` tip-bot for Joerg Roedel
2018-07-21 16:06 ` [PATCH 2/3] " Pavel Machek
2018-07-20 16:22 ` [PATCH 3/3] x86/entry/32: Copy only ptregs on paranoid entry/exit path Joerg Roedel
2018-07-20 17:09 ` Andy Lutomirski
2018-07-20 21:42 ` Joerg Roedel
2018-07-23 3:49 ` [PATCH 0/3] PTI for x86-32 Fixes and Updates David H. Gutteridge
2018-07-23 7:29 ` Joerg Roedel
2018-07-26 3:47 ` David H. Gutteridge
2018-07-23 14:09 ` Pavel Machek
2018-07-23 19:00 ` Linus Torvalds
2018-07-23 21:38 ` Pavel Machek
2018-07-23 21:50 ` Andy Lutomirski
2018-07-23 21:55 ` Pavel Machek
2018-07-24 21:18 ` Pavel Machek
2018-07-23 21:59 ` Josh Poimboeuf
2018-07-23 22:07 ` Dave Hansen
2018-07-24 13:39 ` Pavel Machek
2018-07-24 14:39 ` Andy Lutomirski
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